Down-integrate from internal code base.

225 files changed, 26872 insertions, 4970 deletions

diff --git a/Makefile.am b/Makefile.am
index bb735177..6ebe3639 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -215,6 +215,7 @@ java_EXTRA_DIST=                                                             \
   java/src/main/java/com/google/protobuf/Message.java                        \
   java/src/main/java/com/google/protobuf/MessageLite.java                    \
   java/src/main/java/com/google/protobuf/MessageLiteOrBuilder.java           \
+  java/src/main/java/com/google/protobuf/MessageLiteToString.java            \
   java/src/main/java/com/google/protobuf/MessageOrBuilder.java               \
   java/src/main/java/com/google/protobuf/MessageReflection.java              \
   java/src/main/java/com/google/protobuf/MutabilityOracle.java               \
@@ -233,6 +234,7 @@ java_EXTRA_DIST=                                                             \
   java/src/main/java/com/google/protobuf/SingleFieldBuilder.java             \
   java/src/main/java/com/google/protobuf/SmallSortedMap.java                 \
   java/src/main/java/com/google/protobuf/TextFormat.java                     \
+  java/src/main/java/com/google/protobuf/TextFormatEscaper.java              \
   java/src/main/java/com/google/protobuf/UninitializedMessageException.java  \
   java/src/main/java/com/google/protobuf/UnknownFieldSet.java                \
   java/src/main/java/com/google/protobuf/UnknownFieldSetLite.java            \
@@ -504,6 +506,7 @@ objectivec_EXTRA_DIST=                                                       \
 
 python_EXTRA_DIST=                                                           \
   python/MANIFEST.in                                                         \
+  python/google/protobuf/internal/any_test.proto                             \
   python/google/protobuf/internal/api_implementation.cc                      \
   python/google/protobuf/internal/api_implementation.py                      \
   python/google/protobuf/internal/containers.py                              \
@@ -540,6 +543,8 @@ python_EXTRA_DIST=                                                           \
   python/google/protobuf/internal/text_format_test.py                        \
   python/google/protobuf/internal/type_checkers.py                           \
   python/google/protobuf/internal/unknown_fields_test.py                     \
+  python/google/protobuf/internal/well_known_types.py                        \
+  python/google/protobuf/internal/well_known_types_test.py                   \
   python/google/protobuf/internal/wire_format.py                             \
   python/google/protobuf/internal/wire_format_test.py                        \
   python/google/protobuf/internal/__init__.py                                \
@@ -558,8 +563,6 @@ python_EXTRA_DIST=                                                           \
   python/google/protobuf/pyext/extension_dict.cc                             \
   python/google/protobuf/pyext/message.h                                     \
   python/google/protobuf/pyext/message.cc                                    \
-  python/google/protobuf/pyext/message_map_container.cc                      \
-  python/google/protobuf/pyext/message_map_container.h                       \
   python/google/protobuf/pyext/proto2_api_test.proto                         \
   python/google/protobuf/pyext/python.proto                                  \
   python/google/protobuf/pyext/python_protobuf.h                             \
@@ -567,8 +570,6 @@ python_EXTRA_DIST=                                                           \
   python/google/protobuf/pyext/repeated_composite_container.cc               \
   python/google/protobuf/pyext/repeated_scalar_container.h                   \
   python/google/protobuf/pyext/repeated_scalar_container.cc                  \
-  python/google/protobuf/pyext/scalar_map_container.cc                       \
-  python/google/protobuf/pyext/scalar_map_container.h                        \
   python/google/protobuf/pyext/scoped_pyobject_ptr.h                         \
   python/google/protobuf/pyext/__init__.py                                   \
   python/google/protobuf/descriptor.py                                       \
diff --git a/appveyor.yml b/appveyor.yml
index 3447602e..c84ecae2 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,32 +1,32 @@
-# Only test one combination: "Visual Studio 12 + Win64 + Debug + DLL". We can

-# test more combinations but AppVeyor just takes too long to finish (each

-# combination takes ~15mins).

-platform:

-  - Win64

-

-configuration:

-  - Debug

-

-environment:

-  matrix:

-    - language: cpp

-      BUILD_DLL: ON

-

-    - language: csharp

-

-install:

-  - ps: Start-FileDownload https://googlemock.googlecode.com/files/gmock-1.7.0.zip

-  - 7z x gmock-1.7.0.zip

-  - rename gmock-1.7.0 gmock

-

-before_build:

-  - if %platform%==Win32 set generator=Visual Studio 12

-  - if %platform%==Win64 set generator=Visual Studio 12 Win64

-  - if %platform%==Win32 set vcplatform=Win32

-  - if %platform%==Win64 set vcplatform=x64

-

-build_script:

-  - CALL appveyor.bat

-

-skip_commits:

-  message: /.*\[skip appveyor\].*/

+# Only test one combination: "Visual Studio 12 + Win64 + Debug + DLL". We can
+# test more combinations but AppVeyor just takes too long to finish (each
+# combination takes ~15mins).
+platform:
+  - Win64
+
+configuration:
+  - Debug
+
+environment:
+  matrix:
+    - language: cpp
+      BUILD_DLL: ON
+
+    - language: csharp
+
+install:
+  - ps: Start-FileDownload https://googlemock.googlecode.com/files/gmock-1.7.0.zip
+  - 7z x gmock-1.7.0.zip
+  - rename gmock-1.7.0 gmock
+
+before_build:
+  - if %platform%==Win32 set generator=Visual Studio 12
+  - if %platform%==Win64 set generator=Visual Studio 12 Win64
+  - if %platform%==Win32 set vcplatform=Win32
+  - if %platform%==Win64 set vcplatform=x64
+
+build_script:
+  - CALL appveyor.bat
+
+skip_commits:
+  message: /.*\[skip appveyor\].*/
diff --git a/cmake/extract_includes.bat.in b/cmake/extract_includes.bat.in
index f6d8b893..49964501 100644
--- a/cmake/extract_includes.bat.in
+++ b/cmake/extract_includes.bat.in
@@ -6,6 +6,7 @@ mkdir include\google\protobuf\compiler\cpp
 mkdir include\google\protobuf\compiler\csharp
 mkdir include\google\protobuf\compiler\java
 mkdir include\google\protobuf\compiler\javanano
+mkdir include\google\protobuf\compiler\js
 mkdir include\google\protobuf\compiler\objectivec
 mkdir include\google\protobuf\compiler\python
 mkdir include\google\protobuf\compiler\ruby
@@ -26,6 +27,7 @@ copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\importer.h in
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\java\java_generator.h include\google\protobuf\compiler\java\java_generator.h
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\java\java_names.h include\google\protobuf\compiler\java\java_names.h
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\javanano\javanano_generator.h include\google\protobuf\compiler\javanano\javanano_generator.h
+copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\js\js_generator.h include\google\protobuf\compiler\js\js_generator.h
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\objectivec\objectivec_generator.h include\google\protobuf\compiler\objectivec\objectivec_generator.h
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\objectivec\objectivec_helpers.h include\google\protobuf\compiler\objectivec\objectivec_helpers.h
 copy ${PROTOBUF_SOURCE_WIN32_PATH}\..\src\google\protobuf\compiler\parser.h include\google\protobuf\compiler\parser.h
diff --git a/cmake/libprotobuf.cmake b/cmake/libprotobuf.cmake
index a6ee8f2e..8930c1ca 100644
--- a/cmake/libprotobuf.cmake
+++ b/cmake/libprotobuf.cmake
@@ -40,6 +40,7 @@ set(libprotobuf_files
   ${protobuf_source_dir}/src/google/protobuf/util/internal/json_objectwriter.cc
   ${protobuf_source_dir}/src/google/protobuf/util/internal/json_stream_parser.cc
   ${protobuf_source_dir}/src/google/protobuf/util/internal/object_writer.cc
+  ${protobuf_source_dir}/src/google/protobuf/util/internal/proto_writer.cc
   ${protobuf_source_dir}/src/google/protobuf/util/internal/protostream_objectsource.cc
   ${protobuf_source_dir}/src/google/protobuf/util/internal/protostream_objectwriter.cc
   ${protobuf_source_dir}/src/google/protobuf/util/internal/type_info.cc
diff --git a/cmake/libprotoc.cmake b/cmake/libprotoc.cmake
index 4e628905..e70e453e 100644
--- a/cmake/libprotoc.cmake
+++ b/cmake/libprotoc.cmake
@@ -70,6 +70,7 @@ set(libprotoc_files
   ${protobuf_source_dir}/src/google/protobuf/compiler/javanano/javanano_message.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/javanano/javanano_message_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/javanano/javanano_primitive_field.cc
+  ${protobuf_source_dir}/src/google/protobuf/compiler/js/js_generator.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
   ${protobuf_source_dir}/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
diff --git a/conformance/ConformanceJava.java b/conformance/ConformanceJava.java
index 25646b85..a983ba3c 100644
--- a/conformance/ConformanceJava.java
+++ b/conformance/ConformanceJava.java
@@ -1,9 +1,12 @@
 
 import com.google.protobuf.conformance.Conformance;
+import com.google.protobuf.util.JsonFormat;
+import com.google.protobuf.util.JsonFormat.TypeRegistry;
 import com.google.protobuf.InvalidProtocolBufferException;
 
 class ConformanceJava {
   private int testCount = 0;
+  private TypeRegistry typeRegistry;
 
   private boolean readFromStdin(byte[] buf, int len) throws Exception {
     int ofs = 0;
@@ -29,7 +32,10 @@ class ConformanceJava {
     if (!readFromStdin(buf, 4)) {
       return -1;
     }
-    return buf[0] | (buf[1] << 1) | (buf[2] << 2) | (buf[3] << 3);
+    return (buf[0] & 0xff)
+        | ((buf[1] & 0xff) << 8)
+        | ((buf[2] & 0xff) << 16)
+        | ((buf[3] & 0xff) << 24);
   }
 
   private void writeLittleEndianIntToStdout(int val) throws Exception {
@@ -54,7 +60,15 @@ class ConformanceJava {
         break;
       }
       case JSON_PAYLOAD: {
-        return Conformance.ConformanceResponse.newBuilder().setSkipped("JSON not yet supported.").build();
+        try {
+          Conformance.TestAllTypes.Builder builder = Conformance.TestAllTypes.newBuilder();
+          JsonFormat.parser().usingTypeRegistry(typeRegistry)
+              .merge(request.getJsonPayload(), builder);
+          testMessage = builder.build();
+        } catch (InvalidProtocolBufferException e) {
+          return Conformance.ConformanceResponse.newBuilder().setParseError(e.getMessage()).build();
+        }
+        break;
       }
       case PAYLOAD_NOT_SET: {
         throw new RuntimeException("Request didn't have payload.");
@@ -73,7 +87,13 @@ class ConformanceJava {
         return Conformance.ConformanceResponse.newBuilder().setProtobufPayload(testMessage.toByteString()).build();
 
       case JSON:
-        return Conformance.ConformanceResponse.newBuilder().setSkipped("JSON not yet supported.").build();
+        try {
+          return Conformance.ConformanceResponse.newBuilder().setJsonPayload(
+              JsonFormat.printer().usingTypeRegistry(typeRegistry).print(testMessage)).build();
+        } catch (InvalidProtocolBufferException | IllegalArgumentException e) {
+          return Conformance.ConformanceResponse.newBuilder().setSerializeError(
+              e.getMessage()).build();
+        }
 
       default: {
         throw new RuntimeException("Unexpected request output.");
@@ -106,6 +126,8 @@ class ConformanceJava {
   }
 
   public void run() throws Exception {
+    typeRegistry = TypeRegistry.newBuilder().add(
+        Conformance.TestAllTypes.getDescriptor()).build();
     while (doTestIo()) {
       // Empty.
     }
diff --git a/conformance/conformance.proto b/conformance/conformance.proto
index 714cbe78..fc96074a 100644
--- a/conformance/conformance.proto
+++ b/conformance/conformance.proto
@@ -32,6 +32,13 @@ syntax = "proto3";
 package conformance;
 option java_package = "com.google.protobuf.conformance";
 
+import "google/protobuf/any.proto";
+import "google/protobuf/duration.proto";
+import "google/protobuf/field_mask.proto";
+import "google/protobuf/struct.proto";
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/wrappers.proto";
+
 // This defines the conformance testing protocol.  This protocol exists between
 // the conformance test suite itself and the code being tested.  For each test,
 // the suite will send a ConformanceRequest message and expect a
@@ -84,6 +91,11 @@ message ConformanceResponse {
     // test.  Some of the test cases are intentionally invalid input.
     string parse_error = 1;
 
+    // If the input was successfully parsed but errors occurred when
+    // serializing it to the requested output format, set the error message in
+    // this field.
+    string serialize_error = 6;
+
     // This should be set if some other error occurred.  This will always
     // indicate that the test failed.  The string can provide more information
     // about the failure.
@@ -199,6 +211,55 @@ message TestAllTypes {
     string oneof_string = 113;
     bytes oneof_bytes = 114;
   }
+
+  // Well-known types
+  google.protobuf.BoolValue optional_bool_wrapper = 201;
+  google.protobuf.Int32Value optional_int32_wrapper = 202;
+  google.protobuf.Int64Value optional_int64_wrapper = 203;
+  google.protobuf.UInt32Value optional_uint32_wrapper = 204;
+  google.protobuf.UInt64Value optional_uint64_wrapper = 205;
+  google.protobuf.FloatValue optional_float_wrapper = 206;
+  google.protobuf.DoubleValue optional_double_wrapper = 207;
+  google.protobuf.StringValue optional_string_wrapper = 208;
+  google.protobuf.BytesValue optional_bytes_wrapper = 209;
+
+  repeated google.protobuf.BoolValue repeated_bool_wrapper = 211;
+  repeated google.protobuf.Int32Value repeated_int32_wrapper = 212;
+  repeated google.protobuf.Int64Value repeated_int64_wrapper = 213;
+  repeated google.protobuf.UInt32Value repeated_uint32_wrapper = 214;
+  repeated google.protobuf.UInt64Value repeated_uint64_wrapper = 215;
+  repeated google.protobuf.FloatValue repeated_float_wrapper = 216;
+  repeated google.protobuf.DoubleValue repeated_double_wrapper = 217;
+  repeated google.protobuf.StringValue repeated_string_wrapper = 218;
+  repeated google.protobuf.BytesValue repeated_bytes_wrapper = 219;
+
+  google.protobuf.Duration optional_duration = 301;
+  google.protobuf.Timestamp optional_timestamp = 302;
+  google.protobuf.FieldMask optional_field_mask = 303;
+  google.protobuf.Struct optional_struct = 304;
+  google.protobuf.Any optional_any = 305;
+  google.protobuf.Value optional_value = 306;
+
+  repeated google.protobuf.Duration repeated_duration = 311;
+  repeated google.protobuf.Timestamp repeated_timestamp = 312;
+  repeated google.protobuf.FieldMask repeated_fieldmask = 313;
+  repeated google.protobuf.Struct repeated_struct = 324;
+  repeated google.protobuf.Any repeated_any = 315;
+  repeated google.protobuf.Value repeated_value = 316;
+
+  // Test field-name-to-JSON-name convention.
+  int32 fieldname1 = 401;
+  int32 field_name2 = 402;
+  int32 _field_name3 = 403;
+  int32 field__name4_ = 404;
+  int32 field0name5 = 405;
+  int32 field_0_name6 = 406;
+  int32 fieldName7 = 407;
+  int32 FieldName8 = 408;
+  int32 field_Name9 = 409;
+  int32 Field_Name10 = 410;
+  int32 FIELD_NAME11 = 411;
+  int32 FIELD_name12 = 412;
 }
 
 message ForeignMessage {
diff --git a/conformance/conformance_cpp.cc b/conformance/conformance_cpp.cc
index 863b6a5b..1a265493 100644
--- a/conformance/conformance_cpp.cc
+++ b/conformance/conformance_cpp.cc
@@ -108,7 +108,11 @@ void DoTest(const ConformanceRequest& request, ConformanceResponse* response) {
         return;
       }
 
-      GOOGLE_CHECK(test_message.ParseFromString(proto_binary));
+      if (!test_message.ParseFromString(proto_binary)) {
+        response->set_runtime_error(
+            "Parsing JSON generates invalid proto output.");
+        return;
+      }
       break;
     }
 
@@ -132,9 +136,18 @@ void DoTest(const ConformanceRequest& request, ConformanceResponse* response) {
       GOOGLE_CHECK(test_message.SerializeToString(&proto_binary));
       Status status = BinaryToJsonString(type_resolver, *type_url, proto_binary,
                                          response->mutable_json_payload());
-      GOOGLE_CHECK(status.ok());
+      if (!status.ok()) {
+        response->set_serialize_error(
+            string("Failed to serialize JSON output: ") +
+            status.error_message().as_string());
+        return;
+      }
       break;
     }
+
+    default:
+      GOOGLE_LOG(FATAL) << "Unknown output format: "
+                        << request.requested_output_format();
   }
 }
 
diff --git a/conformance/conformance_test.cc b/conformance/conformance_test.cc
index c250cb1e..0516bb29 100644
--- a/conformance/conformance_test.cc
+++ b/conformance/conformance_test.cc
@@ -37,10 +37,14 @@
 #include <google/protobuf/stubs/stringprintf.h>
 #include <google/protobuf/text_format.h>
 #include <google/protobuf/util/json_util.h>
+#include <google/protobuf/util/field_comparator.h>
 #include <google/protobuf/util/message_differencer.h>
 #include <google/protobuf/util/type_resolver_util.h>
 #include <google/protobuf/wire_format_lite.h>
 
+#include "third_party/jsoncpp/value.h"
+#include "third_party/jsoncpp/reader.h"
+
 using conformance::ConformanceRequest;
 using conformance::ConformanceResponse;
 using conformance::TestAllTypes;
@@ -49,6 +53,7 @@ using google::protobuf::Descriptor;
 using google::protobuf::FieldDescriptor;
 using google::protobuf::internal::WireFormatLite;
 using google::protobuf::TextFormat;
+using google::protobuf::util::DefaultFieldComparator;
 using google::protobuf::util::JsonToBinaryString;
 using google::protobuf::util::MessageDifferencer;
 using google::protobuf::util::NewTypeResolverForDescriptorPool;
@@ -220,7 +225,7 @@ void ConformanceTestSuite::RunTest(const string& test_name,
   string serialized_response;
   request.SerializeToString(&serialized_request);
 
-  runner_->RunTest(serialized_request, &serialized_response);
+  runner_->RunTest(test_name, serialized_request, &serialized_response);
 
   if (!response->ParseFromString(serialized_response)) {
     response->Clear();
@@ -240,7 +245,9 @@ void ConformanceTestSuite::RunValidInputTest(
     const string& equivalent_text_format, WireFormat requested_output) {
   TestAllTypes reference_message;
   GOOGLE_CHECK(
-      TextFormat::ParseFromString(equivalent_text_format, &reference_message));
+      TextFormat::ParseFromString(equivalent_text_format, &reference_message))
+          << "Failed to parse data for test case: " << test_name
+          << ", data: " << equivalent_text_format;
 
   ConformanceRequest request;
   ConformanceResponse response;
@@ -254,9 +261,8 @@ void ConformanceTestSuite::RunValidInputTest(
       request.set_json_payload(input);
       break;
 
-    case conformance::UNSPECIFIED:
+    default:
       GOOGLE_LOG(FATAL) << "Unspecified input format";
-
   }
 
   request.set_requested_output_format(requested_output);
@@ -268,8 +274,9 @@ void ConformanceTestSuite::RunValidInputTest(
   switch (response.result_case()) {
     case ConformanceResponse::kParseError:
     case ConformanceResponse::kRuntimeError:
+    case ConformanceResponse::kSerializeError:
       ReportFailure(test_name, request, response,
-                    "Failed to parse valid JSON input.");
+                    "Failed to parse JSON input or produce JSON output.");
       return;
 
     case ConformanceResponse::kSkipped:
@@ -313,13 +320,20 @@ void ConformanceTestSuite::RunValidInputTest(
 
       break;
     }
+
+    default:
+      GOOGLE_LOG(FATAL) << test_name << ": unknown payload type: "
+                        << response.result_case();
   }
 
   MessageDifferencer differencer;
+  DefaultFieldComparator field_comparator;
+  field_comparator.set_treat_nan_as_equal(true);
+  differencer.set_field_comparator(&field_comparator);
   string differences;
   differencer.ReportDifferencesToString(&differences);
 
-  if (differencer.Equals(reference_message, test_message)) {
+  if (differencer.Compare(reference_message, test_message)) {
     ReportSuccess(test_name);
   } else {
     ReportFailure(test_name, request, response,
@@ -362,13 +376,103 @@ void ConformanceTestSuite::ExpectHardParseFailureForProto(
 void ConformanceTestSuite::RunValidJsonTest(
     const string& test_name, const string& input_json,
     const string& equivalent_text_format) {
-  RunValidInputTest("JsonInput." + test_name + ".JsonOutput", input_json,
+  RunValidInputTest("JsonInput." + test_name + ".ProtobufOutput", input_json,
                     conformance::JSON, equivalent_text_format,
                     conformance::PROTOBUF);
-  RunValidInputTest("JsonInput." + test_name + ".ProtobufOutput", input_json, conformance::JSON,
+  RunValidInputTest("JsonInput." + test_name + ".JsonOutput", input_json,
+                    conformance::JSON, equivalent_text_format,
+                    conformance::JSON);
+}
+
+void ConformanceTestSuite::RunValidJsonTestWithProtobufInput(
+    const string& test_name, const TestAllTypes& input,
+    const string& equivalent_text_format) {
+  RunValidInputTest("ProtobufInput." + test_name + ".JsonOutput",
+                    input.SerializeAsString(), conformance::PROTOBUF,
                     equivalent_text_format, conformance::JSON);
 }
 
+// According to proto3 JSON specification, JSON serializers follow more strict
+// rules than parsers (e.g., a serializer must serialize int32 values as JSON
+// numbers while the parser is allowed to accept them as JSON strings). This
+// method allows strict checking on a proto3 JSON serializer by inspecting
+// the JSON output directly.
+void ConformanceTestSuite::RunValidJsonTestWithValidator(
+    const string& test_name, const string& input_json,
+    const Validator& validator) {
+  ConformanceRequest request;
+  ConformanceResponse response;
+  request.set_json_payload(input_json);
+  request.set_requested_output_format(conformance::JSON);
+
+  string effective_test_name = "JsonInput." + test_name + ".Validator";
+
+  RunTest(effective_test_name, request, &response);
+
+  if (response.result_case() != ConformanceResponse::kJsonPayload) {
+    ReportFailure(effective_test_name, request, response,
+                  "Expected JSON payload but got type %d.",
+                  response.result_case());
+    return;
+  }
+  Json::Reader reader;
+  Json::Value value;
+  if (!reader.parse(response.json_payload(), value)) {
+    ReportFailure(effective_test_name, request, response,
+                  "JSON payload cannot be parsed as valid JSON: %s",
+                  reader.getFormattedErrorMessages().c_str());
+    return;
+  }
+  if (!validator(value)) {
+    ReportFailure(effective_test_name, request, response,
+                  "JSON payload validation failed.");
+    return;
+  }
+  ReportSuccess(effective_test_name);
+}
+
+void ConformanceTestSuite::ExpectParseFailureForJson(
+    const string& test_name, const string& input_json) {
+  ConformanceRequest request;
+  ConformanceResponse response;
+  request.set_json_payload(input_json);
+  string effective_test_name = "JsonInput." + test_name;
+
+  // We don't expect output, but if the program erroneously accepts the protobuf
+  // we let it send its response as this.  We must not leave it unspecified.
+  request.set_requested_output_format(conformance::JSON);
+
+  RunTest(effective_test_name, request, &response);
+  if (response.result_case() == ConformanceResponse::kParseError) {
+    ReportSuccess(effective_test_name);
+  } else {
+    ReportFailure(effective_test_name, request, response,
+                  "Should have failed to parse, but didn't.");
+  }
+}
+
+void ConformanceTestSuite::ExpectSerializeFailureForJson(
+    const string& test_name, const string& text_format) {
+  TestAllTypes payload_message;
+  GOOGLE_CHECK(
+      TextFormat::ParseFromString(text_format, &payload_message))
+          << "Failed to parse: " << text_format;
+
+  ConformanceRequest request;
+  ConformanceResponse response;
+  request.set_protobuf_payload(payload_message.SerializeAsString());
+  string effective_test_name = test_name + ".JsonOutput";
+  request.set_requested_output_format(conformance::JSON);
+
+  RunTest(effective_test_name, request, &response);
+  if (response.result_case() == ConformanceResponse::kSerializeError) {
+    ReportSuccess(effective_test_name);
+  } else {
+    ReportFailure(effective_test_name, request, response,
+                  "Should have failed to serialize, but didn't.");
+  }
+}
+
 void ConformanceTestSuite::TestPrematureEOFForType(FieldDescriptor::Type type) {
   // Incomplete values for each wire type.
   static const string incompletes[6] = {
@@ -500,20 +604,1373 @@ bool ConformanceTestSuite::RunSuite(ConformanceTestRunner* runner,
   RunValidJsonTest("HelloWorld", "{\"optionalString\":\"Hello, World!\"}",
                    "optional_string: 'Hello, World!'");
 
-  bool ok =
-      CheckSetEmpty(expected_to_fail_,
-                    "These tests were listed in the failure list, but they "
-                    "don't exist.  Remove them from the failure list") &&
+  // Test field name conventions.
+  RunValidJsonTest(
+      "FieldNameInSnakeCase",
+      R"({
+        "fieldname1": 1,
+        "fieldName2": 2,
+        "FieldName3": 3
+      })",
+      R"(
+        fieldname1: 1
+        field_name2: 2
+        _field_name3: 3
+      )");
+  RunValidJsonTest(
+      "FieldNameWithNumbers",
+      R"({
+        "field0name5": 5,
+        "field0Name6": 6
+      })",
+      R"(
+        field0name5: 5
+        field_0_name6: 6
+      )");
+  RunValidJsonTest(
+      "FieldNameWithMixedCases",
+      R"({
+        "fieldName7": 7,
+        "fieldName8": 8,
+        "fieldName9": 9,
+        "fieldName10": 10,
+        "fIELDNAME11": 11,
+        "fIELDName12": 12
+      })",
+      R"(
+        fieldName7: 7
+        FieldName8: 8
+        field_Name9: 9
+        Field_Name10: 10
+        FIELD_NAME11: 11
+        FIELD_name12: 12
+      )");
+  // Using the original proto field name in JSON is also allowed.
+  RunValidJsonTest(
+      "OriginalProtoFieldName",
+      R"({
+        "fieldname1": 1,
+        "field_name2": 2,
+        "_field_name3": 3,
+        "field0name5": 5,
+        "field_0_name6": 6,
+        "fieldName7": 7,
+        "FieldName8": 8,
+        "field_Name9": 9,
+        "Field_Name10": 10,
+        "FIELD_NAME11": 11,
+        "FIELD_name12": 12
+      })",
+      R"(
+        fieldname1: 1
+        field_name2: 2
+        _field_name3: 3
+        field0name5: 5
+        field_0_name6: 6
+        fieldName7: 7
+        FieldName8: 8
+        field_Name9: 9
+        Field_Name10: 10
+        FIELD_NAME11: 11
+        FIELD_name12: 12
+      )");
+  // Field names can be escaped.
+  RunValidJsonTest(
+      "FieldNameEscaped",
+      R"({"fieldn\u0061me1": 1})",
+      "fieldname1: 1");
+  // Field names must be quoted (or it's not valid JSON).
+  ExpectParseFailureForJson(
+      "FieldNameNotQuoted",
+      "{fieldname1: 1}");
+  // Trailing comma is not allowed (not valid JSON).
+  ExpectParseFailureForJson(
+      "TrailingCommaInAnObject",
+      R"({"fieldname1":1,})");
+  // JSON doesn't support comments.
+  ExpectParseFailureForJson(
+      "JsonWithComments",
+      R"({
+        // This is a comment.
+        "fieldname1": 1
+      })");
+  // Duplicated field names are not allowed.
+  ExpectParseFailureForJson(
+      "FieldNameDuplicate",
+      R"({
+        "optionalNestedMessage": {a: 1},
+        "optionalNestedMessage": {}
+      })");
+  ExpectParseFailureForJson(
+      "FieldNameDuplicateDifferentCasing1",
+      R"({
+        "optional_nested_message": {a: 1},
+        "optionalNestedMessage": {}
+      })");
+  ExpectParseFailureForJson(
+      "FieldNameDuplicateDifferentCasing2",
+      R"({
+        "optionalNestedMessage": {a: 1},
+        "optional_nested_message": {}
+      })");
+  // Serializers should use lowerCamelCase by default.
+  RunValidJsonTestWithValidator(
+      "FieldNameInLowerCamelCase",
+      R"({
+        "fieldname1": 1,
+        "fieldName2": 2,
+        "FieldName3": 3
+      })",
+      [](const Json::Value& value) {
+        return value.isMember("fieldname1") &&
+            value.isMember("fieldName2") &&
+            value.isMember("FieldName3");
+      });
+  RunValidJsonTestWithValidator(
+      "FieldNameWithNumbers",
+      R"({
+        "field0name5": 5,
+        "field0Name6": 6
+      })",
+      [](const Json::Value& value) {
+        return value.isMember("field0name5") &&
+            value.isMember("field0Name6");
+      });
+  RunValidJsonTestWithValidator(
+      "FieldNameWithMixedCases",
+      R"({
+        "fieldName7": 7,
+        "fieldName8": 8,
+        "fieldName9": 9,
+        "fieldName10": 10,
+        "fIELDNAME11": 11,
+        "fIELDName12": 12
+      })",
+      [](const Json::Value& value) {
+        return value.isMember("fieldName7") &&
+            value.isMember("fieldName8") &&
+            value.isMember("fieldName9") &&
+            value.isMember("fieldName10") &&
+            value.isMember("fIELDNAME11") &&
+            value.isMember("fIELDName12");
+      });
+
+  // Integer fields.
+  RunValidJsonTest(
+      "Int32FieldMaxValue",
+      R"({"optionalInt32": 2147483647})",
+      "optional_int32: 2147483647");
+  RunValidJsonTest(
+      "Int32FieldMinValue",
+      R"({"optionalInt32": -2147483648})",
+      "optional_int32: -2147483648");
+  RunValidJsonTest(
+      "Uint32FieldMaxValue",
+      R"({"optionalUint32": 4294967295})",
+      "optional_uint32: 4294967295");
+  RunValidJsonTest(
+      "Int64FieldMaxValue",
+      R"({"optionalInt64": "9223372036854775807"})",
+      "optional_int64: 9223372036854775807");
+  RunValidJsonTest(
+      "Int64FieldMinValue",
+      R"({"optionalInt64": "-9223372036854775808"})",
+      "optional_int64: -9223372036854775808");
+  RunValidJsonTest(
+      "Uint64FieldMaxValue",
+      R"({"optionalUint64": "18446744073709551615"})",
+      "optional_uint64: 18446744073709551615");
+  RunValidJsonTest(
+      "Int64FieldMaxValueNotQuoted",
+      R"({"optionalInt64": 9223372036854775807})",
+      "optional_int64: 9223372036854775807");
+  RunValidJsonTest(
+      "Int64FieldMinValueNotQuoted",
+      R"({"optionalInt64": -9223372036854775808})",
+      "optional_int64: -9223372036854775808");
+  RunValidJsonTest(
+      "Uint64FieldMaxValueNotQuoted",
+      R"({"optionalUint64": 18446744073709551615})",
+      "optional_uint64: 18446744073709551615");
+  // Values can be represented as JSON strings.
+  RunValidJsonTest(
+      "Int32FieldStringValue",
+      R"({"optionalInt32": "2147483647"})",
+      "optional_int32: 2147483647");
+  RunValidJsonTest(
+      "Int32FieldStringValueEscaped",
+      R"({"optionalInt32": "2\u003147483647"})",
+      "optional_int32: 2147483647");
+
+  // Parsers reject out-of-bound integer values.
+  ExpectParseFailureForJson(
+      "Int32FieldTooLarge",
+      R"({"optionalInt32": 2147483648})");
+  ExpectParseFailureForJson(
+      "Int32FieldTooSmall",
+      R"({"optionalInt32": -2147483649})");
+  ExpectParseFailureForJson(
+      "Uint32FieldTooLarge",
+      R"({"optionalUint32": 4294967296})");
+  ExpectParseFailureForJson(
+      "Int64FieldTooLarge",
+      R"({"optionalInt64": "9223372036854775808"})");
+  ExpectParseFailureForJson(
+      "Int64FieldTooSmall",
+      R"({"optionalInt64": "-9223372036854775809"})");
+  ExpectParseFailureForJson(
+      "Uint64FieldTooLarge",
+      R"({"optionalUint64": "18446744073709551616"})");
+  // Parser reject non-integer numeric values as well.
+  ExpectParseFailureForJson(
+      "Int32FieldNotInteger",
+      R"({"optionalInt32": 0.5})");
+  ExpectParseFailureForJson(
+      "Uint32FieldNotInteger",
+      R"({"optionalUint32": 0.5})");
+  ExpectParseFailureForJson(
+      "Int64FieldNotInteger",
+      R"({"optionalInt64": "0.5"})");
+  ExpectParseFailureForJson(
+      "Uint64FieldNotInteger",
+      R"({"optionalUint64": "0.5"})");
+
+  // Integers but represented as float values are accepted.
+  RunValidJsonTest(
+      "Int32FieldFloatTrailingZero",
+      R"({"optionalInt32": 100000.000})",
+      "optional_int32: 100000");
+  RunValidJsonTest(
+      "Int32FieldExponentialFormat",
+      R"({"optionalInt32": 1e5})",
+      "optional_int32: 100000");
+  RunValidJsonTest(
+      "Int32FieldMaxFloatValue",
+      R"({"optionalInt32": 2.147483647e9})",
+      "optional_int32: 2147483647");
+  RunValidJsonTest(
+      "Int32FieldMinFloatValue",
+      R"({"optionalInt32": -2.147483648e9})",
+      "optional_int32: -2147483648");
+  RunValidJsonTest(
+      "Uint32FieldMaxFloatValue",
+      R"({"optionalUint32": 4.294967295e9})",
+      "optional_uint32: 4294967295");
+
+  // Parser reject non-numeric values.
+  ExpectParseFailureForJson(
+      "Int32FieldNotNumber",
+      R"({"optionalInt32": "3x3"})");
+  ExpectParseFailureForJson(
+      "Uint32FieldNotNumber",
+      R"({"optionalUint32": "3x3"})");
+  ExpectParseFailureForJson(
+      "Int64FieldNotNumber",
+      R"({"optionalInt64": "3x3"})");
+  ExpectParseFailureForJson(
+      "Uint64FieldNotNumber",
+      R"({"optionalUint64": "3x3"})");
+  // JSON does not allow "+" on numric values.
+  ExpectParseFailureForJson(
+      "Int32FieldPlusSign",
+      R"({"optionalInt32": +1})");
+  // JSON doesn't allow leading 0s.
+  ExpectParseFailureForJson(
+      "Int32FieldLeadingZero",
+      R"({"optionalInt32": 01})");
+  ExpectParseFailureForJson(
+      "Int32FieldNegativeWithLeadingZero",
+      R"({"optionalInt32": -01})");
+  // String values must follow the same syntax rule. Specifically leading
+  // or traling spaces are not allowed.
+  ExpectParseFailureForJson(
+      "Int32FieldLeadingSpace",
+      R"({"optionalInt32": " 1"})");
+  ExpectParseFailureForJson(
+      "Int32FieldTrailingSpace",
+      R"({"optionalInt32": "1 "})");
+
+  // 64-bit values are serialized as strings.
+  RunValidJsonTestWithValidator(
+      "Int64FieldBeString",
+      R"({"optionalInt64": 1})",
+      [](const Json::Value& value) {
+        return value["optionalInt64"].type() == Json::stringValue &&
+            value["optionalInt64"].asString() == "1";
+      });
+  RunValidJsonTestWithValidator(
+      "Uint64FieldBeString",
+      R"({"optionalUint64": 1})",
+      [](const Json::Value& value) {
+        return value["optionalUint64"].type() == Json::stringValue &&
+            value["optionalUint64"].asString() == "1";
+      });
+
+  // Bool fields.
+  RunValidJsonTest(
+      "BoolFieldTrue",
+      R"({"optionalBool":true})",
+      "optional_bool: true");
+  RunValidJsonTest(
+      "BoolFieldFalse",
+      R"({"optionalBool":false})",
+      "optional_bool: false");
+
+  // Other forms are not allowed.
+  ExpectParseFailureForJson(
+      "BoolFieldIntegerZero",
+      R"({"optionalBool":0})");
+  ExpectParseFailureForJson(
+      "BoolFieldIntegerOne",
+      R"({"optionalBool":1})");
+  ExpectParseFailureForJson(
+      "BoolFieldCamelCaseTrue",
+      R"({"optionalBool":True})");
+  ExpectParseFailureForJson(
+      "BoolFieldCamelCaseFalse",
+      R"({"optionalBool":False})");
+  ExpectParseFailureForJson(
+      "BoolFieldAllCapitalTrue",
+      R"({"optionalBool":TRUE})");
+  ExpectParseFailureForJson(
+      "BoolFieldAllCapitalFalse",
+      R"({"optionalBool":FALSE})");
+  ExpectParseFailureForJson(
+      "BoolFieldDoubleQuotedTrue",
+      R"({"optionalBool":"true"})");
+  ExpectParseFailureForJson(
+      "BoolFieldDoubleQuotedFalse",
+      R"({"optionalBool":"false"})");
+
+  // Float fields.
+  RunValidJsonTest(
+      "FloatFieldMinPositiveValue",
+      R"({"optionalFloat": 1.175494e-38})",
+      "optional_float: 1.175494e-38");
+  RunValidJsonTest(
+      "FloatFieldMaxNegativeValue",
+      R"({"optionalFloat": -1.175494e-38})",
+      "optional_float: -1.175494e-38");
+  RunValidJsonTest(
+      "FloatFieldMaxPositiveValue",
+      R"({"optionalFloat": 3.402823e+38})",
+      "optional_float: 3.402823e+38");
+  RunValidJsonTest(
+      "FloatFieldMinNegativeValue",
+      R"({"optionalFloat": 3.402823e+38})",
+      "optional_float: 3.402823e+38");
+  // Values can be quoted.
+  RunValidJsonTest(
+      "FloatFieldQuotedValue",
+      R"({"optionalFloat": "1"})",
+      "optional_float: 1");
+  // Special values.
+  RunValidJsonTest(
+      "FloatFieldNan",
+      R"({"optionalFloat": "NaN"})",
+      "optional_float: nan");
+  RunValidJsonTest(
+      "FloatFieldInfinity",
+      R"({"optionalFloat": "Infinity"})",
+      "optional_float: inf");
+  RunValidJsonTest(
+      "FloatFieldNegativeInfinity",
+      R"({"optionalFloat": "-Infinity"})",
+      "optional_float: -inf");
+  // Non-cannonical Nan will be correctly normalized.
+  {
+    TestAllTypes message;
+    // IEEE floating-point standard 32-bit quiet NaN:
+    //   0111 1111 1xxx xxxx xxxx xxxx xxxx xxxx
+    message.set_optional_float(
+        WireFormatLite::DecodeFloat(0x7FA12345));
+    RunValidJsonTestWithProtobufInput(
+        "FloatFieldNormalizeQuietNan", message,
+        "optional_float: nan");
+    // IEEE floating-point standard 64-bit signaling NaN:
+    //   1111 1111 1xxx xxxx xxxx xxxx xxxx xxxx
+    message.set_optional_float(
+        WireFormatLite::DecodeFloat(0xFFB54321));
+    RunValidJsonTestWithProtobufInput(
+        "FloatFieldNormalizeSignalingNan", message,
+        "optional_float: nan");
+  }
 
-      CheckSetEmpty(unexpected_failing_tests_,
-                    "These tests failed.  If they can't be fixed right now, "
-                    "you can add them to the failure list so the overall "
-                    "suite can succeed") &&
+  // Special values must be quoted.
+  ExpectParseFailureForJson(
+      "FloatFieldNanNotQuoted",
+      R"({"optionalFloat": NaN})");
+  ExpectParseFailureForJson(
+      "FloatFieldInfinityNotQuoted",
+      R"({"optionalFloat": Infinity})");
+  ExpectParseFailureForJson(
+      "FloatFieldNegativeInfinityNotQuoted",
+      R"({"optionalFloat": -Infinity})");
+  // Parsers should reject out-of-bound values.
+  ExpectParseFailureForJson(
+      "FloatFieldTooSmall",
+      R"({"optionalFloat": -3.502823e+38})");
+  ExpectParseFailureForJson(
+      "FloatFieldTooLarge",
+      R"({"optionalFloat": 3.502823e+38})");
+
+  // Double fields.
+  RunValidJsonTest(
+      "DoubleFieldMinPositiveValue",
+      R"({"optionalDouble": 2.22507e-308})",
+      "optional_double: 2.22507e-308");
+  RunValidJsonTest(
+      "DoubleFieldMaxNegativeValue",
+      R"({"optionalDouble": -2.22507e-308})",
+      "optional_double: -2.22507e-308");
+  RunValidJsonTest(
+      "DoubleFieldMaxPositiveValue",
+      R"({"optionalDouble": 1.79769e+308})",
+      "optional_double: 1.79769e+308");
+  RunValidJsonTest(
+      "DoubleFieldMinNegativeValue",
+      R"({"optionalDouble": -1.79769e+308})",
+      "optional_double: -1.79769e+308");
+  // Values can be quoted.
+  RunValidJsonTest(
+      "DoubleFieldQuotedValue",
+      R"({"optionalDouble": "1"})",
+      "optional_double: 1");
+  // Speical values.
+  RunValidJsonTest(
+      "DoubleFieldNan",
+      R"({"optionalDouble": "NaN"})",
+      "optional_double: nan");
+  RunValidJsonTest(
+      "DoubleFieldInfinity",
+      R"({"optionalDouble": "Infinity"})",
+      "optional_double: inf");
+  RunValidJsonTest(
+      "DoubleFieldNegativeInfinity",
+      R"({"optionalDouble": "-Infinity"})",
+      "optional_double: -inf");
+  // Non-cannonical Nan will be correctly normalized.
+  {
+    TestAllTypes message;
+    message.set_optional_double(
+        WireFormatLite::DecodeDouble(0x7FFA123456789ABCLL));
+    RunValidJsonTestWithProtobufInput(
+        "DoubleFieldNormalizeQuietNan", message,
+        "optional_double: nan");
+    message.set_optional_double(
+        WireFormatLite::DecodeDouble(0xFFFBCBA987654321LL));
+    RunValidJsonTestWithProtobufInput(
+        "DoubleFieldNormalizeSignalingNan", message,
+        "optional_double: nan");
+  }
+
+  // Special values must be quoted.
+  ExpectParseFailureForJson(
+      "DoubleFieldNanNotQuoted",
+      R"({"optionalDouble": NaN})");
+  ExpectParseFailureForJson(
+      "DoubleFieldInfinityNotQuoted",
+      R"({"optionalDouble": Infinity})");
+  ExpectParseFailureForJson(
+      "DoubleFieldNegativeInfinityNotQuoted",
+      R"({"optionalDouble": -Infinity})");
+
+  // Parsers should reject out-of-bound values.
+  ExpectParseFailureForJson(
+      "DoubleFieldTooSmall",
+      R"({"optionalDouble": -1.89769e+308})");
+  ExpectParseFailureForJson(
+      "DoubleFieldTooLarge",
+      R"({"optionalDouble": +1.89769e+308})");
+
+  // Enum fields.
+  RunValidJsonTest(
+      "EnumField",
+      R"({"optionalNestedEnum": "FOO"})",
+      "optional_nested_enum: FOO");
+  // Enum values must be represented as strings.
+  ExpectParseFailureForJson(
+      "EnumFieldNotQuoted",
+      R"({"optionalNestedEnum": FOO})");
+  // Numeric values are allowed.
+  RunValidJsonTest(
+      "EnumFieldNumericValueZero",
+      R"({"optionalNestedEnum": 0})",
+      "optional_nested_enum: FOO");
+  RunValidJsonTest(
+      "EnumFieldNumericValueNonZero",
+      R"({"optionalNestedEnum": 1})",
+      "optional_nested_enum: BAR");
+  // Unknown enum values are represented as numeric values.
+  RunValidJsonTestWithValidator(
+      "EnumFieldUnknownValue",
+      R"({"optionalNestedEnum": 123})",
+      [](const Json::Value& value) {
+        return value["optionalNestedEnum"].type() == Json::intValue &&
+            value["optionalNestedEnum"].asInt() == 123;
+      });
+
+  // String fields.
+  RunValidJsonTest(
+      "StringField",
+      R"({"optionalString": "Hello world!"})",
+      "optional_string: \"Hello world!\"");
+  RunValidJsonTest(
+      "StringFieldUnicode",
+      // Google in Chinese.
+      R"({"optionalString": "谷歌"})",
+      R"(optional_string: "谷歌")");
+  RunValidJsonTest(
+      "StringFieldEscape",
+      R"({"optionalString": "\"\\\/\b\f\n\r\t"})",
+      R"(optional_string: "\"\\/\b\f\n\r\t")");
+  RunValidJsonTest(
+      "StringFieldUnicodeEscape",
+      R"({"optionalString": "\u8C37\u6B4C"})",
+      R"(optional_string: "谷歌")");
+  RunValidJsonTest(
+      "StringFieldUnicodeEscapeWithLowercaseHexLetters",
+      R"({"optionalString": "\u8c37\u6b4c"})",
+      R"(optional_string: "谷歌")");
+  RunValidJsonTest(
+      "StringFieldSurrogatePair",
+      // The character is an emoji: grinning face with smiling eyes. 😁
+      R"({"optionalString": "\uD83D\uDE01"})",
+      R"(optional_string: "\xF0\x9F\x98\x81")");
+
+  // Unicode escapes must start with "\u" (lowercase u).
+  ExpectParseFailureForJson(
+      "StringFieldUppercaseEscapeLetter",
+      R"({"optionalString": "\U8C37\U6b4C"})");
+  ExpectParseFailureForJson(
+      "StringFieldInvalidEscape",
+      R"({"optionalString": "\uXXXX\u6B4C"})");
+  ExpectParseFailureForJson(
+      "StringFieldUnterminatedEscape",
+      R"({"optionalString": "\u8C3"})");
+  ExpectParseFailureForJson(
+      "StringFieldUnpairedHighSurrogate",
+      R"({"optionalString": "\uD800"})");
+  ExpectParseFailureForJson(
+      "StringFieldUnpairedLowSurrogate",
+      R"({"optionalString": "\uDC00"})");
+  ExpectParseFailureForJson(
+      "StringFieldSurrogateInWrongOrder",
+      R"({"optionalString": "\uDE01\uD83D"})");
+  ExpectParseFailureForJson(
+      "StringFieldNotAString",
+      R"({"optionalString": 12345})");
+
+  // Bytes fields.
+  RunValidJsonTest(
+      "BytesField",
+      R"({"optionalBytes": "AQI="})",
+      R"(optional_bytes: "\x01\x02")");
+  ExpectParseFailureForJson(
+      "BytesFieldNoPadding",
+      R"({"optionalBytes": "AQI"})");
+  ExpectParseFailureForJson(
+      "BytesFieldInvalidBase64Characters",
+      R"({"optionalBytes": "-_=="})");
+
+  // Message fields.
+  RunValidJsonTest(
+      "MessageField",
+      R"({"optionalNestedMessage": {"a": 1234}})",
+      "optional_nested_message: {a: 1234}");
+
+  // Oneof fields.
+  ExpectParseFailureForJson(
+      "OneofFieldDuplicate",
+      R"({"oneofUint32": 1, "oneofString": "test"})");
+
+  // Repeated fields.
+  RunValidJsonTest(
+      "PrimitiveRepeatedField",
+      R"({"repeatedInt32": [1, 2, 3, 4]})",
+      "repeated_int32: [1, 2, 3, 4]");
+  RunValidJsonTest(
+      "EnumRepeatedField",
+      R"({"repeatedNestedEnum": ["FOO", "BAR", "BAZ"]})",
+      "repeated_nested_enum: [FOO, BAR, BAZ]");
+  RunValidJsonTest(
+      "StringRepeatedField",
+      R"({"repeatedString": ["Hello", "world"]})",
+      R"(repeated_string: ["Hello", "world"])");
+  RunValidJsonTest(
+      "BytesRepeatedField",
+      R"({"repeatedBytes": ["AAEC", "AQI="]})",
+      R"(repeated_bytes: ["\x00\x01\x02", "\x01\x02"])");
+  RunValidJsonTest(
+      "MessageRepeatedField",
+      R"({"repeatedNestedMessage": [{"a": 1234}, {"a": 5678}]})",
+      "repeated_nested_message: {a: 1234}"
+      "repeated_nested_message: {a: 5678}");
+
+  // Repeated field elements are of incorrect type.
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingIntegersGotBool",
+      R"({"repeatedInt32": [1, false, 3, 4]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingIntegersGotString",
+      R"({"repeatedInt32": [1, 2, "name", 4]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingIntegersGotMessage",
+      R"({"repeatedInt32": [1, 2, 3, {"a": 4}]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingStringsGotInt",
+      R"({"repeatedString": ["1", 2, "3", "4"]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingStringsGotBool",
+      R"({"repeatedString": ["1", "2", false, "4"]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingStringsGotMessage",
+      R"({"repeatedString": ["1", 2, "3", {"a": 4}]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingMessagesGotInt",
+      R"({"repeatedNestedMessage": [{"a": 1}, 2]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingMessagesGotBool",
+      R"({"repeatedNestedMessage": [{"a": 1}, false]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldWrongElementTypeExpectingMessagesGotString",
+      R"({"repeatedNestedMessage": [{"a": 1}, "2"]})");
+  // Trailing comma in the repeated field is not allowed.
+  ExpectParseFailureForJson(
+      "RepeatedFieldTrailingComma",
+      R"({"repeatedInt32": [1, 2, 3, 4,]})");
+
+  // Map fields.
+  RunValidJsonTest(
+      "Int32MapField",
+      R"({"mapInt32Int32": {"1": 2, "3": 4}})",
+      "map_int32_int32: {key: 1 value: 2}"
+      "map_int32_int32: {key: 3 value: 4}");
+  ExpectParseFailureForJson(
+      "Int32MapFieldKeyNotQuoted",
+      R"({"mapInt32Int32": {1: 2, 3: 4}})");
+  RunValidJsonTest(
+      "Uint32MapField",
+      R"({"mapUint32Uint32": {"1": 2, "3": 4}})",
+      "map_uint32_uint32: {key: 1 value: 2}"
+      "map_uint32_uint32: {key: 3 value: 4}");
+  ExpectParseFailureForJson(
+      "Uint32MapFieldKeyNotQuoted",
+      R"({"mapUint32Uint32": {1: 2, 3: 4}})");
+  RunValidJsonTest(
+      "Int64MapField",
+      R"({"mapInt64Int64": {"1": 2, "3": 4}})",
+      "map_int64_int64: {key: 1 value: 2}"
+      "map_int64_int64: {key: 3 value: 4}");
+  ExpectParseFailureForJson(
+      "Int64MapFieldKeyNotQuoted",
+      R"({"mapInt64Int64": {1: 2, 3: 4}})");
+  RunValidJsonTest(
+      "Uint64MapField",
+      R"({"mapUint64Uint64": {"1": 2, "3": 4}})",
+      "map_uint64_uint64: {key: 1 value: 2}"
+      "map_uint64_uint64: {key: 3 value: 4}");
+  ExpectParseFailureForJson(
+      "Uint64MapFieldKeyNotQuoted",
+      R"({"mapUint64Uint64": {1: 2, 3: 4}})");
+  RunValidJsonTest(
+      "BoolMapField",
+      R"({"mapBoolBool": {"true": true, "false": false}})",
+      "map_bool_bool: {key: true value: true}"
+      "map_bool_bool: {key: false value: false}");
+  ExpectParseFailureForJson(
+      "BoolMapFieldKeyNotQuoted",
+      R"({"mapBoolBool": {true: true, false: false}})");
+  RunValidJsonTest(
+      "MessageMapField",
+      R"({
+        "mapStringNestedMessage": {
+          "hello": {"a": 1234},
+          "world": {"a": 5678}
+        }
+      })",
+      R"(
+        map_string_nested_message: {
+          key: "hello"
+          value: {a: 1234}
+        }
+        map_string_nested_message: {
+          key: "world"
+          value: {a: 5678}
+        }
+      )");
+  // Since Map keys are represented as JSON strings, escaping should be allowed.
+  RunValidJsonTest(
+      "Int32MapEscapedKey",
+      R"({"mapInt32Int32": {"\u0031": 2}})",
+      "map_int32_int32: {key: 1 value: 2}");
+  RunValidJsonTest(
+      "Int64MapEscapedKey",
+      R"({"mapInt64Int64": {"\u0031": 2}})",
+      "map_int64_int64: {key: 1 value: 2}");
+  RunValidJsonTest(
+      "BoolMapEscapedKey",
+      R"({"mapBoolBool": {"tr\u0075e": true}})",
+      "map_bool_bool: {key: true value: true}");
+
+  // "null" is accepted for all fields types.
+  RunValidJsonTest(
+      "AllFieldAcceptNull",
+      R"({
+        "optionalInt32": null,
+        "optionalInt64": null,
+        "optionalUint32": null,
+        "optionalUint64": null,
+        "optionalBool": null,
+        "optionalString": null,
+        "optionalBytes": null,
+        "optionalNestedEnum": null,
+        "optionalNestedMessage": null,
+        "repeatedInt32": null,
+        "repeatedInt64": null,
+        "repeatedUint32": null,
+        "repeatedUint64": null,
+        "repeatedBool": null,
+        "repeatedString": null,
+        "repeatedBytes": null,
+        "repeatedNestedEnum": null,
+        "repeatedNestedMessage": null,
+        "mapInt32Int32": null,
+        "mapBoolBool": null,
+        "mapStringNestedMessage": null
+      })",
+      "");
+
+  // Repeated field elements cannot be null.
+  ExpectParseFailureForJson(
+      "RepeatedFieldPrimitiveElementIsNull",
+      R"({"repeatedInt32": [1, null, 2]})");
+  ExpectParseFailureForJson(
+      "RepeatedFieldMessageElementIsNull",
+      R"({"repeatedNestedMessage": [{"a":1}, null, {"a":2}]})");
+  // Map field keys cannot be null.
+  ExpectParseFailureForJson(
+      "MapFieldKeyIsNull",
+      R"({"mapInt32Int32": {null: 1}})");
+  // Map field values cannot be null.
+  ExpectParseFailureForJson(
+      "MapFieldValueIsNull",
+      R"({"mapInt32Int32": {"0": null}})");
+
+  // Wrapper types.
+  RunValidJsonTest(
+      "OptionalBoolWrapper",
+      R"({"optionalBoolWrapper": false})",
+      "optional_bool_wrapper: {value: false}");
+  RunValidJsonTest(
+      "OptionalInt32Wrapper",
+      R"({"optionalInt32Wrapper": 0})",
+      "optional_int32_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalUint32Wrapper",
+      R"({"optionalUint32Wrapper": 0})",
+      "optional_uint32_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalInt64Wrapper",
+      R"({"optionalInt64Wrapper": 0})",
+      "optional_int64_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalUint64Wrapper",
+      R"({"optionalUint64Wrapper": 0})",
+      "optional_uint64_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalFloatWrapper",
+      R"({"optionalFloatWrapper": 0})",
+      "optional_float_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalDoubleWrapper",
+      R"({"optionalDoubleWrapper": 0})",
+      "optional_double_wrapper: {value: 0}");
+  RunValidJsonTest(
+      "OptionalStringWrapper",
+      R"({"optionalStringWrapper": ""})",
+      R"(optional_string_wrapper: {value: ""})");
+  RunValidJsonTest(
+      "OptionalBytesWrapper",
+      R"({"optionalBytesWrapper": ""})",
+      R"(optional_bytes_wrapper: {value: ""})");
+  RunValidJsonTest(
+      "OptionalWrapperTypesWithNonDefaultValue",
+      R"({
+        "optionalBoolWrapper": true,
+        "optionalInt32Wrapper": 1,
+        "optionalUint32Wrapper": 1,
+        "optionalInt64Wrapper": "1",
+        "optionalUint64Wrapper": "1",
+        "optionalFloatWrapper": 1,
+        "optionalDoubleWrapper": 1,
+        "optionalStringWrapper": "1",
+        "optionalBytesWrapper": "AQI="
+      })",
+      R"(
+        optional_bool_wrapper: {value: true}
+        optional_int32_wrapper: {value: 1}
+        optional_uint32_wrapper: {value: 1}
+        optional_int64_wrapper: {value: 1}
+        optional_uint64_wrapper: {value: 1}
+        optional_float_wrapper: {value: 1}
+        optional_double_wrapper: {value: 1}
+        optional_string_wrapper: {value: "1"}
+        optional_bytes_wrapper: {value: "\x01\x02"}
+      )");
+  RunValidJsonTest(
+      "RepeatedBoolWrapper",
+      R"({"repeatedBoolWrapper": [true, false]})",
+      "repeated_bool_wrapper: {value: true}"
+      "repeated_bool_wrapper: {value: false}");
+  RunValidJsonTest(
+      "RepeatedInt32Wrapper",
+      R"({"repeatedInt32Wrapper": [0, 1]})",
+      "repeated_int32_wrapper: {value: 0}"
+      "repeated_int32_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedUint32Wrapper",
+      R"({"repeatedUint32Wrapper": [0, 1]})",
+      "repeated_uint32_wrapper: {value: 0}"
+      "repeated_uint32_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedInt64Wrapper",
+      R"({"repeatedInt64Wrapper": [0, 1]})",
+      "repeated_int64_wrapper: {value: 0}"
+      "repeated_int64_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedUint64Wrapper",
+      R"({"repeatedUint64Wrapper": [0, 1]})",
+      "repeated_uint64_wrapper: {value: 0}"
+      "repeated_uint64_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedFloatWrapper",
+      R"({"repeatedFloatWrapper": [0, 1]})",
+      "repeated_float_wrapper: {value: 0}"
+      "repeated_float_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedDoubleWrapper",
+      R"({"repeatedDoubleWrapper": [0, 1]})",
+      "repeated_double_wrapper: {value: 0}"
+      "repeated_double_wrapper: {value: 1}");
+  RunValidJsonTest(
+      "RepeatedStringWrapper",
+      R"({"repeatedStringWrapper": ["", "AQI="]})",
+      R"(
+        repeated_string_wrapper: {value: ""}
+        repeated_string_wrapper: {value: "AQI="}
+      )");
+  RunValidJsonTest(
+      "RepeatedBytesWrapper",
+      R"({"repeatedBytesWrapper": ["", "AQI="]})",
+      R"(
+        repeated_bytes_wrapper: {value: ""}
+        repeated_bytes_wrapper: {value: "\x01\x02"}
+      )");
+  RunValidJsonTest(
+      "WrapperTypesWithNullValue",
+      R"({
+        "optionalBoolWrapper": null,
+        "optionalInt32Wrapper": null,
+        "optionalUint32Wrapper": null,
+        "optionalInt64Wrapper": null,
+        "optionalUint64Wrapper": null,
+        "optionalFloatWrapper": null,
+        "optionalDoubleWrapper": null,
+        "optionalStringWrapper": null,
+        "optionalBytesWrapper": null,
+        "repeatedBoolWrapper": null,
+        "repeatedInt32Wrapper": null,
+        "repeatedUint32Wrapper": null,
+        "repeatedInt64Wrapper": null,
+        "repeatedUint64Wrapper": null,
+        "repeatedFloatWrapper": null,
+        "repeatedDoubleWrapper": null,
+        "repeatedStringWrapper": null,
+        "repeatedBytesWrapper": null
+      })",
+      "");
+
+  // Duration
+  RunValidJsonTest(
+      "DurationMinValue",
+      R"({"optionalDuration": "-315576000000.999999999s"})",
+      "optional_duration: {seconds: -315576000000 nanos: -999999999}");
+  RunValidJsonTest(
+      "DurationMaxValue",
+      R"({"optionalDuration": "315576000000.999999999s"})",
+      "optional_duration: {seconds: 315576000000 nanos: 999999999}");
+  RunValidJsonTest(
+      "DurationRepeatedValue",
+      R"({"repeatedDuration": ["1.5s", "-1.5s"]})",
+      "repeated_duration: {seconds: 1 nanos: 500000000}"
+      "repeated_duration: {seconds: -1 nanos: -500000000}");
+
+  ExpectParseFailureForJson(
+      "DurationMissingS",
+      R"({"optionalDuration": "1"})");
+  ExpectParseFailureForJson(
+      "DurationJsonInputTooSmall",
+      R"({"optionalDuration": "-315576000001.000000000s"})");
+  ExpectParseFailureForJson(
+      "DurationJsonInputTooLarge",
+      R"({"optionalDuration": "315576000001.000000000s"})");
+  ExpectSerializeFailureForJson(
+      "DurationProtoInputTooSmall",
+      "optional_duration: {seconds: -315576000001 nanos: 0}");
+  ExpectSerializeFailureForJson(
+      "DurationProtoInputTooLarge",
+      "optional_duration: {seconds: 315576000001 nanos: 0}");
+
+  RunValidJsonTestWithValidator(
+      "DurationHasZeroFractionalDigit",
+      R"({"optionalDuration": "1.000000000s"})",
+      [](const Json::Value& value) {
+        return value["optionalDuration"].asString() == "1s";
+      });
+  RunValidJsonTestWithValidator(
+      "DurationHas3FractionalDigits",
+      R"({"optionalDuration": "1.010000000s"})",
+      [](const Json::Value& value) {
+        return value["optionalDuration"].asString() == "1.010s";
+      });
+  RunValidJsonTestWithValidator(
+      "DurationHas6FractionalDigits",
+      R"({"optionalDuration": "1.000010000s"})",
+      [](const Json::Value& value) {
+        return value["optionalDuration"].asString() == "1.000010s";
+      });
+  RunValidJsonTestWithValidator(
+      "DurationHas9FractionalDigits",
+      R"({"optionalDuration": "1.000000010s"})",
+      [](const Json::Value& value) {
+        return value["optionalDuration"].asString() == "1.000000010s";
+      });
+
+  // Timestamp
+  RunValidJsonTest(
+      "TimestampMinValue",
+      R"({"optionalTimestamp": "0001-01-01T00:00:00Z"})",
+      "optional_timestamp: {seconds: -62135596800}");
+  RunValidJsonTest(
+      "TimestampMaxValue",
+      R"({"optionalTimestamp": "9999-12-31T23:59:59.999999999Z"})",
+      "optional_timestamp: {seconds: 253402300799 nanos: 999999999}");
+  RunValidJsonTest(
+      "TimestampRepeatedValue",
+      R"({
+        "repeatedTimestamp": [
+          "0001-01-01T00:00:00Z",
+          "9999-12-31T23:59:59.999999999Z"
+        ]
+      })",
+      "repeated_timestamp: {seconds: -62135596800}"
+      "repeated_timestamp: {seconds: 253402300799 nanos: 999999999}");
+  RunValidJsonTest(
+      "TimestampWithPositiveOffset",
+      R"({"optionalTimestamp": "1970-01-01T08:00:00+08:00"})",
+      "optional_timestamp: {seconds: 0}");
+  RunValidJsonTest(
+      "TimestampWithNegativeOffset",
+      R"({"optionalTimestamp": "1969-12-31T16:00:00-08:00"})",
+      "optional_timestamp: {seconds: 0}");
+
+  ExpectParseFailureForJson(
+      "TimestampJsonInputTooSmall",
+      R"({"optionalTimestamp": "0000-01-01T00:00:00Z"})");
+  ExpectParseFailureForJson(
+      "TimestampJsonInputTooLarge",
+      R"({"optionalTimestamp": "10000-01-01T00:00:00Z"})");
+  ExpectParseFailureForJson(
+      "TimestampJsonInputMissingZ",
+      R"({"optionalTimestamp": "0001-01-01T00:00:00"})");
+  ExpectParseFailureForJson(
+      "TimestampJsonInputMissingT",
+      R"({"optionalTimestamp": "0001-01-01 00:00:00Z"})");
+  ExpectParseFailureForJson(
+      "TimestampJsonInputLowercaseZ",
+      R"({"optionalTimestamp": "0001-01-01T00:00:00z"})");
+  ExpectParseFailureForJson(
+      "TimestampJsonInputLowercaseT",
+      R"({"optionalTimestamp": "0001-01-01t00:00:00Z"})");
+  ExpectSerializeFailureForJson(
+      "TimestampProtoInputTooSmall",
+      "optional_timestamp: {seconds: -62135596801}");
+  ExpectSerializeFailureForJson(
+      "TimestampProtoInputTooLarge",
+      "optional_timestamp: {seconds: 253402300800}");
+  RunValidJsonTestWithValidator(
+      "TimestampZeroNormalized",
+      R"({"optionalTimestamp": "1969-12-31T16:00:00-08:00"})",
+      [](const Json::Value& value) {
+        return value["optionalTimestamp"].asString() ==
+            "1970-01-01T00:00:00Z";
+      });
+  RunValidJsonTestWithValidator(
+      "TimestampHasZeroFractionalDigit",
+      R"({"optionalTimestamp": "1970-01-01T00:00:00.000000000Z"})",
+      [](const Json::Value& value) {
+        return value["optionalTimestamp"].asString() ==
+            "1970-01-01T00:00:00Z";
+      });
+  RunValidJsonTestWithValidator(
+      "TimestampHas3FractionalDigits",
+      R"({"optionalTimestamp": "1970-01-01T00:00:00.010000000Z"})",
+      [](const Json::Value& value) {
+        return value["optionalTimestamp"].asString() ==
+            "1970-01-01T00:00:00.010Z";
+      });
+  RunValidJsonTestWithValidator(
+      "TimestampHas6FractionalDigits",
+      R"({"optionalTimestamp": "1970-01-01T00:00:00.000010000Z"})",
+      [](const Json::Value& value) {
+        return value["optionalTimestamp"].asString() ==
+            "1970-01-01T00:00:00.000010Z";
+      });
+  RunValidJsonTestWithValidator(
+      "TimestampHas9FractionalDigits",
+      R"({"optionalTimestamp": "1970-01-01T00:00:00.000000010Z"})",
+      [](const Json::Value& value) {
+        return value["optionalTimestamp"].asString() ==
+            "1970-01-01T00:00:00.000000010Z";
+      });
+
+  // FieldMask
+  RunValidJsonTest(
+      "FieldMask",
+      R"({"optionalFieldMask": "foo,barBaz"})",
+      R"(optional_field_mask: {paths: "foo" paths: "bar_baz"})");
+  ExpectParseFailureForJson(
+      "FieldMaskInvalidCharacter",
+      R"({"optionalFieldMask": "foo,bar_bar"})");
+  ExpectSerializeFailureForJson(
+      "FieldMaskPathsDontRoundTrip",
+      R"(optional_field_mask: {paths: "fooBar"})");
+  ExpectSerializeFailureForJson(
+      "FieldMaskNumbersDontRoundTrip",
+      R"(optional_field_mask: {paths: "foo_3_bar"})");
+  ExpectSerializeFailureForJson(
+      "FieldMaskTooManyUnderscore",
+      R"(optional_field_mask: {paths: "foo__bar"})");
+
+  // Struct
+  RunValidJsonTest(
+      "Struct",
+      R"({
+        "optionalStruct": {
+          "nullValue": null,
+          "intValue": 1234,
+          "boolValue": true,
+          "doubleValue": 1234.5678,
+          "stringValue": "Hello world!",
+          "listValue": [1234, "5678"],
+          "objectValue": {
+            "value": 0
+          }
+        }
+      })",
+      R"(
+        optional_struct: {
+          fields: {
+            key: "nullValue"
+            value: {null_value: NULL_VALUE}
+          }
+          fields: {
+            key: "intValue"
+            value: {number_value: 1234}
+          }
+          fields: {
+            key: "boolValue"
+            value: {bool_value: true}
+          }
+          fields: {
+            key: "doubleValue"
+            value: {number_value: 1234.5678}
+          }
+          fields: {
+            key: "stringValue"
+            value: {string_value: "Hello world!"}
+          }
+          fields: {
+            key: "listValue"
+            value: {
+              list_value: {
+                values: {
+                  number_value: 1234
+                }
+                values: {
+                  string_value: "5678"
+                }
+              }
+            }
+          }
+          fields: {
+            key: "objectValue"
+            value: {
+              struct_value: {
+                fields: {
+                  key: "value"
+                  value: {
+                    number_value: 0
+                  }
+                }
+              }
+            }
+          }
+        }
+      )");
+  // Value
+  RunValidJsonTest(
+      "ValueAcceptInteger",
+      R"({"optionalValue": 1})",
+      "optional_value: { number_value: 1}");
+  RunValidJsonTest(
+      "ValueAcceptFloat",
+      R"({"optionalValue": 1.5})",
+      "optional_value: { number_value: 1.5}");
+  RunValidJsonTest(
+      "ValueAcceptBool",
+      R"({"optionalValue": false})",
+      "optional_value: { bool_value: false}");
+  RunValidJsonTest(
+      "ValueAcceptNull",
+      R"({"optionalValue": null})",
+      "optional_value: { null_value: NULL_VALUE}");
+  RunValidJsonTest(
+      "ValueAcceptString",
+      R"({"optionalValue": "hello"})",
+      R"(optional_value: { string_value: "hello"})");
+  RunValidJsonTest(
+      "ValueAcceptList",
+      R"({"optionalValue": [0, "hello"]})",
+      R"(
+        optional_value: {
+          list_value: {
+            values: {
+              number_value: 0
+            }
+            values: {
+              string_value: "hello"
+            }
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "ValueAcceptObject",
+      R"({"optionalValue": {"value": 1}})",
+      R"(
+        optional_value: {
+          struct_value: {
+            fields: {
+              key: "value"
+              value: {
+                number_value: 1
+              }
+            }
+          }
+        }
+      )");
+
+  // Any
+  RunValidJsonTest(
+      "Any",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/conformance.TestAllTypes",
+          "optionalInt32": 12345
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/conformance.TestAllTypes] {
+            optional_int32: 12345
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyNested",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Any",
+          "value": {
+            "@type": "type.googleapis.com/conformance.TestAllTypes",
+            "optionalInt32": 12345
+          }
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Any] {
+            [type.googleapis.com/conformance.TestAllTypes] {
+              optional_int32: 12345
+            }
+          }
+        }
+      )");
+  // The special "@type" tag is not required to appear first.
+  RunValidJsonTest(
+      "AnyUnorderedTypeTag",
+      R"({
+        "optionalAny": {
+          "optionalInt32": 12345,
+          "@type": "type.googleapis.com/conformance.TestAllTypes"
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/conformance.TestAllTypes] {
+            optional_int32: 12345
+          }
+        }
+      )");
+  // Well-known types in Any.
+  RunValidJsonTest(
+      "AnyWithInt32ValueWrapper",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Int32Value",
+          "value": 12345
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Int32Value] {
+            value: 12345
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithDuration",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Duration",
+          "value": "1.5s"
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Duration] {
+            seconds: 1
+            nanos: 500000000
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithTimestamp",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Timestamp",
+          "value": "1970-01-01T00:00:00Z"
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Timestamp] {
+            seconds: 0
+            nanos: 0
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithFieldMask",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.FieldMask",
+          "value": "foo,barBaz"
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.FieldMask] {
+            paths: ["foo", "bar_baz"]
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithStruct",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Struct",
+          "value": {
+            "foo": 1
+          }
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Struct] {
+            fields: {
+              key: "foo"
+              value: {
+                number_value: 1
+              }
+            }
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithValueForJsonObject",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Value",
+          "value": {
+            "foo": 1
+          }
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Value] {
+            struct_value: {
+              fields: {
+                key: "foo"
+                value: {
+                  number_value: 1
+                }
+              }
+            }
+          }
+        }
+      )");
+  RunValidJsonTest(
+      "AnyWithValueForInteger",
+      R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Value",
+          "value": 1
+        }
+      })",
+      R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Value] {
+            number_value: 1
+          }
+        }
+      )");
+
+  bool ok = true;
+  if (!CheckSetEmpty(expected_to_fail_,
+                     "These tests were listed in the failure list, but they "
+                     "don't exist.  Remove them from the failure list")) {
+    ok = false;
+  }
+  if (!CheckSetEmpty(unexpected_failing_tests_,
+                     "These tests failed.  If they can't be fixed right now, "
+                     "you can add them to the failure list so the overall "
+                     "suite can succeed")) {
+    ok = false;
+  }
 
-      CheckSetEmpty(unexpected_succeeding_tests_,
-                    "These tests succeeded, even though they were listed in "
-                    "the failure list.  Remove them from the failure list");
+  // Sometimes the testee may be fixed before we update the failure list (e.g.,
+  // the testee is from a different component). We warn about this case but
+  // don't consider it an overall test failure.
+  CheckSetEmpty(unexpected_succeeding_tests_,
+                "These tests succeeded, even though they were listed in "
+                "the failure list.  Remove them from the failure list");
 
+  CheckSetEmpty(skipped_,
+                "These tests were skipped (probably because support for some "
+                "features is not implemented)");
   if (verbose_) {
     CheckSetEmpty(skipped_,
                   "These tests were skipped (probably because support for some "
diff --git a/conformance/conformance_test.h b/conformance/conformance_test.h
index 9e6cdaee..b89d3700 100644
--- a/conformance/conformance_test.h
+++ b/conformance/conformance_test.h
@@ -38,14 +38,19 @@
 #ifndef CONFORMANCE_CONFORMANCE_TEST_H
 #define CONFORMANCE_CONFORMANCE_TEST_H
 
+#include <functional>
 #include <string>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/util/type_resolver.h>
 #include <google/protobuf/wire_format_lite.h>
 
+#include "third_party/jsoncpp/value.h"
+#include "third_party/jsoncpp/reader.h"
+
 namespace conformance {
 class ConformanceRequest;
 class ConformanceResponse;
+class TestAllTypes;
 }  // namespace conformance
 
 namespace google {
@@ -53,6 +58,8 @@ namespace protobuf {
 
 class ConformanceTestRunner {
  public:
+  virtual ~ConformanceTestRunner() {}
+
   // Call to run a single conformance test.
   //
   // "input" is a serialized conformance.ConformanceRequest.
@@ -60,7 +67,9 @@ class ConformanceTestRunner {
   //
   // If there is any error in running the test itself, set "runtime_error" in
   // the response.
-  virtual void RunTest(const std::string& input, std::string* output) = 0;
+  virtual void RunTest(const std::string& test_name,
+                       const std::string& input,
+                       std::string* output) = 0;
 };
 
 // Class representing the test suite itself.  To run it, implement your own
@@ -118,6 +127,18 @@ class ConformanceTestSuite {
                          conformance::WireFormat requested_output);
   void RunValidJsonTest(const string& test_name, const string& input_json,
                         const string& equivalent_text_format);
+  void RunValidJsonTestWithProtobufInput(const string& test_name,
+                                         const conformance::TestAllTypes& input,
+                                         const string& equivalent_text_format);
+
+  typedef std::function<bool(const Json::Value&)> Validator;
+  void RunValidJsonTestWithValidator(const string& test_name,
+                                     const string& input_json,
+                                     const Validator& validator);
+  void ExpectParseFailureForJson(const string& test_name,
+                                 const string& input_json);
+  void ExpectSerializeFailureForJson(const string& test_name,
+                                     const string& text_format);
   void ExpectParseFailureForProto(const std::string& proto,
                                   const std::string& test_name);
   void ExpectHardParseFailureForProto(const std::string& proto,
diff --git a/conformance/conformance_test_runner.cc b/conformance/conformance_test_runner.cc
index c3b3db22..f2b0dabf 100644
--- a/conformance/conformance_test_runner.cc
+++ b/conformance/conformance_test_runner.cc
@@ -53,6 +53,7 @@
 //   3. testee sends 4-byte length M (little endian)
 //   4. testee sends M bytes representing a ConformanceResponse proto
 
+#include <algorithm>
 #include <errno.h>
 #include <unistd.h>
 #include <fstream>
@@ -80,13 +81,19 @@ using std::vector;
 class ForkPipeRunner : public google::protobuf::ConformanceTestRunner {
  public:
   ForkPipeRunner(const std::string &executable)
-      : executable_(executable), running_(false) {}
+      : running_(false), executable_(executable) {}
 
-  void RunTest(const std::string& request, std::string* response) {
+  virtual ~ForkPipeRunner() {}
+
+  void RunTest(const std::string& test_name,
+               const std::string& request,
+               std::string* response) {
     if (!running_) {
       SpawnTestProgram();
     }
 
+    current_test_name_ = test_name;
+
     uint32_t len = request.size();
     CheckedWrite(write_fd_, &len, sizeof(uint32_t));
     CheckedWrite(write_fd_, request.c_str(), request.size());
@@ -158,7 +165,9 @@ class ForkPipeRunner : public google::protobuf::ConformanceTestRunner {
 
   void CheckedWrite(int fd, const void *buf, size_t len) {
     if (write(fd, buf, len) != len) {
-      GOOGLE_LOG(FATAL) << "Error writing to test program: " << strerror(errno);
+      GOOGLE_LOG(FATAL) << current_test_name_
+                        << ": error writing to test program: "
+                        << strerror(errno);
     }
   }
 
@@ -168,9 +177,12 @@ class ForkPipeRunner : public google::protobuf::ConformanceTestRunner {
       ssize_t bytes_read = read(fd, (char*)buf + ofs, len);
 
       if (bytes_read == 0) {
-        GOOGLE_LOG(FATAL) << "Unexpected EOF from test program";
+        GOOGLE_LOG(FATAL) << current_test_name_
+                          << ": unexpected EOF from test program";
       } else if (bytes_read < 0) {
-        GOOGLE_LOG(FATAL) << "Error reading from test program: " << strerror(errno);
+        GOOGLE_LOG(FATAL) << current_test_name_
+                          << ": error reading from test program: "
+                          << strerror(errno);
       }
 
       len -= bytes_read;
@@ -182,6 +194,7 @@ class ForkPipeRunner : public google::protobuf::ConformanceTestRunner {
   int read_fd_;
   bool running_;
   std::string executable_;
+  std::string current_test_name_;
 };
 
 void UsageError() {
@@ -223,7 +236,6 @@ void ParseFailureList(const char *filename, vector<string>* failure_list) {
 }
 
 int main(int argc, char *argv[]) {
-  int arg = 1;
   char *program;
   google::protobuf::ConformanceTestSuite suite;
 
diff --git a/conformance/failure_list_cpp.txt b/conformance/failure_list_cpp.txt
index 53d90c99..240d4118 100644
--- a/conformance/failure_list_cpp.txt
+++ b/conformance/failure_list_cpp.txt
@@ -7,6 +7,92 @@
 # TODO(haberman): insert links to corresponding bugs tracking the issue.
 # Should we use GitHub issues or the Google-internal bug tracker?
 
+FieldMaskNumbersDontRoundTrip.JsonOutput
+FieldMaskPathsDontRoundTrip.JsonOutput
+FieldMaskTooManyUnderscore.JsonOutput
+JsonInput.AnyUnorderedTypeTag.JsonOutput
+JsonInput.AnyUnorderedTypeTag.ProtobufOutput
+JsonInput.AnyWithValueForInteger.JsonOutput
+JsonInput.AnyWithValueForInteger.ProtobufOutput
+JsonInput.AnyWithValueForJsonObject.JsonOutput
+JsonInput.AnyWithValueForJsonObject.ProtobufOutput
+JsonInput.BoolFieldDoubleQuotedFalse
+JsonInput.BoolFieldDoubleQuotedTrue
+JsonInput.BoolFieldIntegerOne
+JsonInput.BoolFieldIntegerZero
+JsonInput.BytesFieldInvalidBase64Characters
+JsonInput.BytesFieldNoPadding
+JsonInput.DoubleFieldTooSmall
+JsonInput.DurationHasZeroFractionalDigit.Validator
+JsonInput.DurationJsonInputTooLarge
+JsonInput.DurationJsonInputTooSmall
+JsonInput.DurationMissingS
+JsonInput.EnumFieldUnknownValue.Validator
+JsonInput.FieldMaskInvalidCharacter
+JsonInput.FieldNameDuplicate
+JsonInput.FieldNameDuplicateDifferentCasing1
+JsonInput.FieldNameDuplicateDifferentCasing2
+JsonInput.FieldNameInLowerCamelCase.Validator
+JsonInput.FieldNameInSnakeCase.JsonOutput
+JsonInput.FieldNameInSnakeCase.ProtobufOutput
+JsonInput.FieldNameNotQuoted
+JsonInput.FieldNameWithMixedCases.JsonOutput
+JsonInput.FieldNameWithMixedCases.ProtobufOutput
+JsonInput.FieldNameWithMixedCases.Validator
+JsonInput.FloatFieldTooLarge
+JsonInput.FloatFieldTooSmall
+JsonInput.Int32FieldLeadingSpace
+JsonInput.Int32FieldLeadingZero
+JsonInput.Int32FieldMinFloatValue.JsonOutput
+JsonInput.Int32FieldMinFloatValue.ProtobufOutput
+JsonInput.Int32FieldMinValue.JsonOutput
+JsonInput.Int32FieldMinValue.ProtobufOutput
+JsonInput.Int32FieldNegativeWithLeadingZero
+JsonInput.Int32FieldNotInteger
+JsonInput.Int32FieldNotNumber
+JsonInput.Int32FieldTooLarge
+JsonInput.Int32FieldTooSmall
+JsonInput.Int32FieldTrailingSpace
+JsonInput.Int64FieldNotInteger
+JsonInput.Int64FieldNotNumber
+JsonInput.Int64FieldTooLarge
+JsonInput.Int64FieldTooSmall
+JsonInput.MapFieldValueIsNull
+JsonInput.OneofFieldDuplicate
+JsonInput.RepeatedFieldMessageElementIsNull
+JsonInput.RepeatedFieldPrimitiveElementIsNull
+JsonInput.RepeatedFieldTrailingComma
+JsonInput.RepeatedFieldWrongElementTypeExpectingIntegersGotBool
+JsonInput.RepeatedFieldWrongElementTypeExpectingIntegersGotMessage
+JsonInput.RepeatedFieldWrongElementTypeExpectingIntegersGotString
+JsonInput.RepeatedFieldWrongElementTypeExpectingMessagesGotBool
+JsonInput.RepeatedFieldWrongElementTypeExpectingMessagesGotInt
+JsonInput.RepeatedFieldWrongElementTypeExpectingMessagesGotString
+JsonInput.RepeatedFieldWrongElementTypeExpectingStringsGotBool
+JsonInput.RepeatedFieldWrongElementTypeExpectingStringsGotInt
+JsonInput.RepeatedFieldWrongElementTypeExpectingStringsGotMessage
+JsonInput.StringFieldNotAString
+JsonInput.StringFieldSurrogateInWrongOrder
+JsonInput.StringFieldSurrogatePair.JsonOutput
+JsonInput.StringFieldSurrogatePair.ProtobufOutput
+JsonInput.StringFieldUnpairedHighSurrogate
+JsonInput.StringFieldUnpairedLowSurrogate
+JsonInput.StringFieldUppercaseEscapeLetter
+JsonInput.TimestampJsonInputLowercaseT
+JsonInput.TimestampJsonInputLowercaseZ
+JsonInput.TimestampJsonInputMissingT
+JsonInput.TimestampJsonInputMissingZ
+JsonInput.TimestampJsonInputTooLarge
+JsonInput.TimestampJsonInputTooSmall
+JsonInput.TrailingCommaInAnObject
+JsonInput.Uint32FieldNotInteger
+JsonInput.Uint32FieldNotNumber
+JsonInput.Uint32FieldTooLarge
+JsonInput.Uint64FieldNotInteger
+JsonInput.Uint64FieldNotNumber
+JsonInput.Uint64FieldTooLarge
+JsonInput.WrapperTypesWithNullValue.JsonOutput
+JsonInput.WrapperTypesWithNullValue.ProtobufOutput
 ProtobufInput.PrematureEofBeforeKnownRepeatedValue.MESSAGE
 ProtobufInput.PrematureEofInDelimitedDataForKnownNonRepeatedValue.MESSAGE
 ProtobufInput.PrematureEofInDelimitedDataForKnownRepeatedValue.MESSAGE
@@ -19,3 +105,5 @@ ProtobufInput.PrematureEofInPackedField.SINT64
 ProtobufInput.PrematureEofInPackedField.UINT32
 ProtobufInput.PrematureEofInPackedField.UINT64
 ProtobufInput.PrematureEofInsideKnownRepeatedValue.MESSAGE
+TimestampProtoInputTooLarge.JsonOutput
+TimestampProtoInputTooSmall.JsonOutput
diff --git a/conformance/failure_list_java.txt b/conformance/failure_list_java.txt
new file mode 100644
index 00000000..86af18b9
--- /dev/null
+++ b/conformance/failure_list_java.txt
@@ -0,0 +1,74 @@
+# This is the list of conformance tests that are known to fail for the Java
+# implementation right now.  These should be fixed.
+#
+# By listing them here we can keep tabs on which ones are failing and be sure
+# that we don't introduce regressions in other tests.
+
+FieldMaskNumbersDontRoundTrip.JsonOutput
+FieldMaskPathsDontRoundTrip.JsonOutput
+FieldMaskTooManyUnderscore.JsonOutput
+JsonInput.AnyWithFieldMask.ProtobufOutput
+JsonInput.AnyWithValueForInteger.JsonOutput
+JsonInput.AnyWithValueForJsonObject.JsonOutput
+JsonInput.BoolFieldAllCapitalFalse
+JsonInput.BoolFieldAllCapitalTrue
+JsonInput.BoolFieldCamelCaseFalse
+JsonInput.BoolFieldCamelCaseTrue
+JsonInput.BoolFieldDoubleQuotedFalse
+JsonInput.BoolFieldDoubleQuotedTrue
+JsonInput.BoolMapFieldKeyNotQuoted
+JsonInput.BytesFieldNoPadding
+JsonInput.DoubleFieldInfinityNotQuoted
+JsonInput.DoubleFieldNanNotQuoted
+JsonInput.DoubleFieldNegativeInfinityNotQuoted
+JsonInput.EnumFieldNotQuoted
+JsonInput.EnumFieldNumericValueNonZero.JsonOutput
+JsonInput.EnumFieldNumericValueNonZero.ProtobufOutput
+JsonInput.EnumFieldNumericValueZero.JsonOutput
+JsonInput.EnumFieldNumericValueZero.ProtobufOutput
+JsonInput.EnumFieldUnknownValue.Validator
+JsonInput.FieldMask.ProtobufOutput
+JsonInput.FieldMaskInvalidCharacter
+JsonInput.FieldNameDuplicate
+JsonInput.FieldNameDuplicateDifferentCasing1
+JsonInput.FieldNameDuplicateDifferentCasing2
+JsonInput.FieldNameInSnakeCase.JsonOutput
+JsonInput.FieldNameNotQuoted
+JsonInput.FieldNameWithMixedCases.JsonOutput
+JsonInput.FloatFieldInfinityNotQuoted
+JsonInput.FloatFieldNanNotQuoted
+JsonInput.FloatFieldNegativeInfinityNotQuoted
+JsonInput.Int32FieldExponentialFormat.JsonOutput
+JsonInput.Int32FieldExponentialFormat.ProtobufOutput
+JsonInput.Int32FieldFloatTrailingZero.JsonOutput
+JsonInput.Int32FieldFloatTrailingZero.ProtobufOutput
+JsonInput.Int32FieldLeadingZero
+JsonInput.Int32FieldMaxFloatValue.JsonOutput
+JsonInput.Int32FieldMaxFloatValue.ProtobufOutput
+JsonInput.Int32FieldMinFloatValue.JsonOutput
+JsonInput.Int32FieldMinFloatValue.ProtobufOutput
+JsonInput.Int32FieldMinValue.JsonOutput
+JsonInput.Int32FieldNegativeWithLeadingZero
+JsonInput.Int32FieldPlusSign
+JsonInput.Int32MapFieldKeyNotQuoted
+JsonInput.Int64MapFieldKeyNotQuoted
+JsonInput.JsonWithComments
+JsonInput.MapFieldValueIsNull
+JsonInput.OneofFieldDuplicate
+JsonInput.OriginalProtoFieldName.JsonOutput
+JsonInput.RepeatedFieldMessageElementIsNull
+JsonInput.RepeatedFieldPrimitiveElementIsNull
+JsonInput.RepeatedFieldTrailingComma
+JsonInput.RepeatedFieldWrongElementTypeExpectingStringsGotBool
+JsonInput.RepeatedFieldWrongElementTypeExpectingStringsGotInt
+JsonInput.StringFieldNotAString
+JsonInput.StringFieldSurrogateInWrongOrder
+JsonInput.StringFieldUnpairedHighSurrogate
+JsonInput.StringFieldUnpairedLowSurrogate
+JsonInput.StringFieldUppercaseEscapeLetter
+JsonInput.Uint32FieldMaxFloatValue.JsonOutput
+JsonInput.Uint32FieldMaxFloatValue.ProtobufOutput
+JsonInput.Uint32MapFieldKeyNotQuoted
+JsonInput.Uint64MapFieldKeyNotQuoted
+JsonInput.ValueAcceptNull.JsonOutput
+JsonInput.ValueAcceptNull.ProtobufOutput
diff --git a/java/pom.xml b/java/pom.xml
index 7b99c035..aa5d30ea 100644
--- a/java/pom.xml
+++ b/java/pom.xml
@@ -295,15 +295,19 @@
                 <include>**/MapFieldLite.java</include>
                 <include>**/MessageLite.java</include>
                 <include>**/MessageLiteOrBuilder.java</include>
+                <include>**/MessageLiteToString.java</include>
                 <include>**/MutabilityOracle.java</include>
+                <include>**/NioByteString.java</include>
                 <include>**/Parser.java</include>
                 <include>**/ProtobufArrayList.java</include>
                 <include>**/ProtocolStringList.java</include>
                 <include>**/RopeByteString.java</include>
                 <include>**/SmallSortedMap.java</include>
+                <include>**/TextFormatEscaper.java</include>
                 <include>**/UninitializedMessageException.java</include>
                 <include>**/UnknownFieldSetLite.java</include>
                 <include>**/UnmodifiableLazyStringList.java</include>
+                <include>**/UnsafeByteStrings.java</include>
                 <include>**/Utf8.java</include>
                 <include>**/WireFormat.java</include>
               </includes>
@@ -316,6 +320,7 @@
                 <testInclude>**/LazyMessageLiteTest.java</testInclude>
                 <testInclude>**/LiteTest.java</testInclude>
                 <testInclude>**/LongArrayListTest.java</testInclude>
+                <testInclude>**/NioByteStringTest.java</testInclude>
                 <testInclude>**/ProtobufArrayListTest.java</testInclude>
                 <testInclude>**/UnknownFieldSetLiteTest.java</testInclude>
               </testIncludes>
diff --git a/java/src/main/java/com/google/protobuf/AbstractMessage.java b/java/src/main/java/com/google/protobuf/AbstractMessage.java
index cc89173a..9f418f2b 100644
--- a/java/src/main/java/com/google/protobuf/AbstractMessage.java
+++ b/java/src/main/java/com/google/protobuf/AbstractMessage.java
@@ -30,6 +30,7 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.Descriptors.OneofDescriptor;
 import com.google.protobuf.Internal.EnumLite;
@@ -161,10 +162,18 @@ public abstract class AbstractMessage extends AbstractMessageLite
     Descriptors.Descriptor descriptor = entry.getDescriptorForType();
     Descriptors.FieldDescriptor key = descriptor.findFieldByName("key");
     Descriptors.FieldDescriptor value = descriptor.findFieldByName("value");
-    result.put(entry.getField(key), entry.getField(value));
+    Object fieldValue = entry.getField(value);
+    if (fieldValue instanceof EnumValueDescriptor) {
+      fieldValue = ((EnumValueDescriptor) fieldValue).getNumber();
+    }
+    result.put(entry.getField(key), fieldValue);
     while (iterator.hasNext()) {
       entry = (Message) iterator.next();
-      result.put(entry.getField(key), entry.getField(value));
+      fieldValue = entry.getField(value);
+      if (fieldValue instanceof EnumValueDescriptor) {
+        fieldValue = ((EnumValueDescriptor) fieldValue).getNumber();
+      }
+      result.put(entry.getField(key), fieldValue);
     }
     return result;
   }
diff --git a/java/src/main/java/com/google/protobuf/BooleanArrayList.java b/java/src/main/java/com/google/protobuf/BooleanArrayList.java
index 45492d2f..70e042f5 100644
--- a/java/src/main/java/com/google/protobuf/BooleanArrayList.java
+++ b/java/src/main/java/com/google/protobuf/BooleanArrayList.java
@@ -68,10 +68,17 @@ final class BooleanArrayList
   private int size;
 
   /**
-   * Constructs a new mutable {@code BooleanArrayList}.
+   * Constructs a new mutable {@code BooleanArrayList} with default capacity.
    */
   BooleanArrayList() {
-    array = new boolean[DEFAULT_CAPACITY];
+    this(DEFAULT_CAPACITY);
+  }
+
+  /**
+   * Constructs a new mutable {@code BooleanArrayList} with the provided capacity.
+   */
+  BooleanArrayList(int capacity) {
+    array = new boolean[capacity];
     size = 0;
   }
 
diff --git a/java/src/main/java/com/google/protobuf/BoundedByteString.java b/java/src/main/java/com/google/protobuf/BoundedByteString.java
index b4c3fb1b..934c9030 100644
--- a/java/src/main/java/com/google/protobuf/BoundedByteString.java
+++ b/java/src/main/java/com/google/protobuf/BoundedByteString.java
@@ -33,7 +33,6 @@ package com.google.protobuf;
 import java.io.IOException;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
-import java.util.NoSuchElementException;
 
 /**
  * This class is used to represent the substring of a {@link ByteString} over a
@@ -47,7 +46,7 @@ import java.util.NoSuchElementException;
  *
  * @author carlanton@google.com (Carl Haverl)
  */
-class BoundedByteString extends LiteralByteString {
+final class BoundedByteString extends LiteralByteString {
 
   private final int bytesOffset;
   private final int bytesLength;
@@ -65,16 +64,7 @@ class BoundedByteString extends LiteralByteString {
    */
   BoundedByteString(byte[] bytes, int offset, int length) {
     super(bytes);
-    if (offset < 0) {
-      throw new IllegalArgumentException("Offset too small: " + offset);
-    }
-    if (length < 0) {
-      throw new IllegalArgumentException("Length too small: " + offset);
-    }
-    if ((long) offset + length > bytes.length) {
-      throw new IllegalArgumentException(
-          "Offset+Length too large: " + offset + "+" + length);
-    }
+    checkRange(offset, offset + length, bytes.length);
 
     this.bytesOffset = offset;
     this.bytesLength = length;
@@ -94,14 +84,7 @@ class BoundedByteString extends LiteralByteString {
   public byte byteAt(int index) {
     // We must check the index ourselves as we cannot rely on Java array index
     // checking for substrings.
-    if (index < 0) {
-      throw new ArrayIndexOutOfBoundsException("Index too small: " + index);
-    }
-    if (index >= size()) {
-      throw new ArrayIndexOutOfBoundsException(
-          "Index too large: " + index + ", " + size());
-    }
-
+    checkIndex(index, size());
     return bytes[bytesOffset + index];
   }
 
@@ -119,8 +102,8 @@ class BoundedByteString extends LiteralByteString {
   // ByteString -> byte[]
 
   @Override
-  protected void copyToInternal(byte[] target, int sourceOffset, 
-      int targetOffset, int numberToCopy) {
+  protected void copyToInternal(byte[] target, int sourceOffset, int targetOffset,
+      int numberToCopy) {
     System.arraycopy(bytes, getOffsetIntoBytes() + sourceOffset, target,
         targetOffset, numberToCopy);
   }
@@ -134,47 +117,8 @@ class BoundedByteString extends LiteralByteString {
     return new LiteralByteString(toByteArray());
   }
 
-  private void readObject(ObjectInputStream in) throws IOException {
+  private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws IOException {
     throw new InvalidObjectException(
         "BoundedByteStream instances are not to be serialized directly");
   }
-
-  // =================================================================
-  // ByteIterator
-
-  @Override
-  public ByteIterator iterator() {
-    return new BoundedByteIterator();
-  }
-
-  private class BoundedByteIterator implements ByteIterator {
-
-    private int position;
-    private final int limit;
-
-    private BoundedByteIterator() {
-      position = getOffsetIntoBytes();
-      limit = position + size();
-    }
-
-    public boolean hasNext() {
-      return (position < limit);
-    }
-
-    public Byte next() {
-      // Boxing calls Byte.valueOf(byte), which does not instantiate.
-      return nextByte();
-    }
-
-    public byte nextByte() {
-      if (position >= limit) {
-        throw new NoSuchElementException();
-      }
-      return bytes[position++];
-    }
-
-    public void remove() {
-      throw new UnsupportedOperationException();
-    }
-  }
 }
diff --git a/java/src/main/java/com/google/protobuf/ByteString.java b/java/src/main/java/com/google/protobuf/ByteString.java
index b092bc36..68f20d51 100644
--- a/java/src/main/java/com/google/protobuf/ByteString.java
+++ b/java/src/main/java/com/google/protobuf/ByteString.java
@@ -83,6 +83,13 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    */
   public static final ByteString EMPTY = new LiteralByteString(new byte[0]);
 
+  /**
+   * Cached hash value. Intentionally accessed via a data race, which
+   * is safe because of the Java Memory Model's "no out-of-thin-air values"
+   * guarantees for ints. A value of 0 implies that the hash has not been set.
+   */
+  private int hash = 0;
+
   // This constructor is here to prevent subclassing outside of this package,
   ByteString() {}
 
@@ -105,7 +112,38 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *
    * @return the iterator
    */
-  public abstract ByteIterator iterator();
+  @Override
+  public final ByteIterator iterator() {
+    return new ByteIterator() {
+      private int position = 0;
+      private final int limit = size();
+
+      @Override
+      public boolean hasNext() {
+        return position < limit;
+      }
+
+      @Override
+      public Byte next() {
+        // Boxing calls Byte.valueOf(byte), which does not instantiate.
+        return nextByte();
+      }
+
+      @Override
+      public byte nextByte() {
+        try {
+          return byteAt(position++);
+        } catch (ArrayIndexOutOfBoundsException e) {
+          throw new NoSuchElementException(e.getMessage());
+        }
+      }
+
+      @Override
+      public void remove() {
+        throw new UnsupportedOperationException();
+      }
+    };
+  }
 
   /**
    * This interface extends {@code Iterator<Byte>}, so that we can return an
@@ -134,7 +172,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *
    * @return true if this is zero bytes long
    */
-  public boolean isEmpty() {
+  public final boolean isEmpty() {
     return size() == 0;
   }
 
@@ -150,7 +188,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @throws IndexOutOfBoundsException if {@code beginIndex < 0} or
    *     {@code beginIndex > size()}.
    */
-  public ByteString substring(int beginIndex) {
+  public final ByteString substring(int beginIndex) {
     return substring(beginIndex, size());
   }
 
@@ -175,7 +213,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *         argument is a prefix of the byte sequence represented by
    *         this string; <code>false</code> otherwise.
    */
-  public boolean startsWith(ByteString prefix) {
+  public final boolean startsWith(ByteString prefix) {
     return size() >= prefix.size() &&
            substring(0, prefix.size()).equals(prefix);
   }
@@ -189,7 +227,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *         argument is a suffix of the byte sequence represented by
    *         this string; <code>false</code> otherwise.
    */
-  public boolean endsWith(ByteString suffix) {
+  public final boolean endsWith(ByteString suffix) {
     return size() >= suffix.size() &&
         substring(size() - suffix.size()).equals(suffix);
   }
@@ -309,8 +347,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    */
   public static ByteString readFrom(InputStream streamToDrain)
       throws IOException {
-    return readFrom(
-        streamToDrain, MIN_READ_FROM_CHUNK_SIZE, MAX_READ_FROM_CHUNK_SIZE);
+    return readFrom(streamToDrain, MIN_READ_FROM_CHUNK_SIZE, MAX_READ_FROM_CHUNK_SIZE);
   }
 
   /**
@@ -383,10 +420,10 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
 
       if (bytesRead == 0) {
         return null;
-      } else {
-        // Always make a copy since InputStream could steal a reference to buf.
-        return ByteString.copyFrom(buf, 0, bytesRead);
       }
+
+      // Always make a copy since InputStream could steal a reference to buf.
+      return ByteString.copyFrom(buf, 0, bytesRead);
   }
 
   // =================================================================
@@ -402,12 +439,10 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @param other string to concatenate
    * @return a new {@code ByteString} instance
    */
-  public ByteString concat(ByteString other) {
-    int thisSize = size();
-    int otherSize = other.size();
-    if ((long) thisSize + otherSize >= Integer.MAX_VALUE) {
+  public final ByteString concat(ByteString other) {
+    if (Integer.MAX_VALUE - size() < other.size()) {
       throw new IllegalArgumentException("ByteString would be too long: " +
-                                         thisSize + "+" + otherSize);
+          size() + "+" + other.size());
     }
 
     return RopeByteString.concatenate(this, other);
@@ -426,29 +461,29 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @return new {@code ByteString}
    */
   public static ByteString copyFrom(Iterable<ByteString> byteStrings) {
-    Collection<ByteString> collection;
+    // Determine the size;
+    final int size;
     if (!(byteStrings instanceof Collection)) {
-      collection = new ArrayList<ByteString>();
-      for (ByteString byteString : byteStrings) {
-        collection.add(byteString);
+      int tempSize = 0;
+      for (Iterator<ByteString> iter = byteStrings.iterator(); iter.hasNext();
+          iter.next(), ++tempSize) {
       }
+      size = tempSize;
     } else {
-      collection = (Collection<ByteString>) byteStrings;
+      size = ((Collection<ByteString>) byteStrings).size();
     }
-    ByteString result;
-    if (collection.isEmpty()) {
-      result = EMPTY;
-    } else {
-      result = balancedConcat(collection.iterator(), collection.size());
+
+    if (size == 0) {
+      return EMPTY;
     }
-    return result;
+
+    return balancedConcat(byteStrings.iterator(), size);
   }
 
   // Internal function used by copyFrom(Iterable<ByteString>).
   // Create a balanced concatenation of the next "length" elements from the
   // iterable.
-  private static ByteString balancedConcat(Iterator<ByteString> iterator,
-      int length) {
+  private static ByteString balancedConcat(Iterator<ByteString> iterator, int length) {
     assert length >= 1;
     ByteString result;
     if (length == 1) {
@@ -486,25 +521,10 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @throws IndexOutOfBoundsException if an offset or size is negative or too
    *     large
    */
-  public void copyTo(byte[] target, int sourceOffset, int targetOffset,
+  public final void copyTo(byte[] target, int sourceOffset, int targetOffset,
       int numberToCopy) {
-    if (sourceOffset < 0) {
-      throw new IndexOutOfBoundsException("Source offset < 0: " + sourceOffset);
-    }
-    if (targetOffset < 0) {
-      throw new IndexOutOfBoundsException("Target offset < 0: " + targetOffset);
-    }
-    if (numberToCopy < 0) {
-      throw new IndexOutOfBoundsException("Length < 0: " + numberToCopy);
-    }
-    if (sourceOffset + numberToCopy > size()) {
-      throw new IndexOutOfBoundsException(
-          "Source end offset < 0: " + (sourceOffset + numberToCopy));
-    }
-    if (targetOffset + numberToCopy > target.length) {
-      throw new IndexOutOfBoundsException(
-          "Target end offset < 0: " + (targetOffset + numberToCopy));
-    }
+    checkRange(sourceOffset, sourceOffset + numberToCopy, size());
+    checkRange(targetOffset, targetOffset + numberToCopy, target.length);
     if (numberToCopy > 0) {
       copyToInternal(target, sourceOffset, targetOffset, numberToCopy);
     }
@@ -534,8 +554,8 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *
    * @return copied bytes
    */
-  public byte[] toByteArray() {
-    int size = size();
+  public final byte[] toByteArray() {
+    final int size = size();
     if (size == 0) {
       return Internal.EMPTY_BYTE_ARRAY;
     }
@@ -548,6 +568,10 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * Writes the complete contents of this byte string to
    * the specified output stream argument.
    *
+   * <p>It is assumed that the {@link OutputStream} will not modify the contents passed it
+   * it. It may be possible for a malicious {@link OutputStream} to corrupt
+   * the data underlying the {@link ByteString}.
+   *
    * @param  out  the output stream to which to write the data.
    * @throws IOException  if an I/O error occurs.
    */
@@ -563,30 +587,20 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @throws IndexOutOfBoundsException if an offset or size is negative or too
    *     large
    */
-  void writeTo(OutputStream out, int sourceOffset, int numberToWrite)
+  final void writeTo(OutputStream out, int sourceOffset, int numberToWrite)
       throws IOException {
-    if (sourceOffset < 0) {
-      throw new IndexOutOfBoundsException("Source offset < 0: " + sourceOffset);
-    }
-    if (numberToWrite < 0) {
-      throw new IndexOutOfBoundsException("Length < 0: " + numberToWrite);
-    }
-    if (sourceOffset + numberToWrite > size()) {
-      throw new IndexOutOfBoundsException(
-          "Source end offset exceeded: " + (sourceOffset + numberToWrite));
-    }
+    checkRange(sourceOffset, sourceOffset + numberToWrite, size());
     if (numberToWrite > 0) {
       writeToInternal(out, sourceOffset, numberToWrite);
     }
-
   }
 
   /**
    * Internal version of {@link #writeTo(OutputStream,int,int)} that assumes
    * all error checking has already been done.
    */
-  abstract void writeToInternal(OutputStream out, int sourceOffset,
-      int numberToWrite) throws IOException;
+  abstract void writeToInternal(OutputStream out, int sourceOffset, int numberToWrite)
+      throws IOException;
 
   /**
    * Constructs a read-only {@code java.nio.ByteBuffer} whose content
@@ -618,7 +632,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @return new string
    * @throws UnsupportedEncodingException if charset isn't recognized
    */
-  public String toString(String charsetName)
+  public final String toString(String charsetName)
       throws UnsupportedEncodingException {
     try {
       return toString(Charset.forName(charsetName));
@@ -636,7 +650,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    * @param charset encode using this charset
    * @return new string
    */
-  public String toString(Charset charset) {
+  public final String toString(Charset charset) {
     return size() == 0 ? "" : toStringInternal(charset);
   }
 
@@ -657,7 +671,7 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *
    * @return new string using UTF-8 encoding
    */
-  public String toStringUtf8() {
+  public final String toStringUtf8() {
     return toString(Internal.UTF_8);
   }
 
@@ -716,13 +730,51 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
   public abstract boolean equals(Object o);
 
   /**
-   * Return a non-zero hashCode depending only on the sequence of bytes
-   * in this ByteString.
+   * Base class for leaf {@link ByteString}s (i.e. non-ropes).
+   */
+  abstract static class LeafByteString extends ByteString {
+    @Override
+    protected final int getTreeDepth() {
+      return 0;
+    }
+
+    @Override
+    protected final boolean isBalanced() {
+      return true;
+    }
+
+    /**
+     * Check equality of the substring of given length of this object starting at
+     * zero with another {@code ByteString} substring starting at offset.
+     *
+     * @param other  what to compare a substring in
+     * @param offset offset into other
+     * @param length number of bytes to compare
+     * @return true for equality of substrings, else false.
+     */
+    abstract boolean equalsRange(ByteString other, int offset, int length);
+  }
+
+  /**
+   * Compute the hashCode using the traditional algorithm from {@link
+   * ByteString}.
    *
-   * @return hashCode value for this object
+   * @return hashCode value
    */
   @Override
-  public abstract int hashCode();
+  public final int hashCode() {
+    int h = hash;
+
+    if (h == 0) {
+      int size = size();
+      h = partialHash(size, 0, size);
+      if (h == 0) {
+        h = 1;
+      }
+      hash = h;
+    }
+    return h;
+  }
 
   // =================================================================
   // Input stream
@@ -1034,7 +1086,9 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    *
    * @return value of cached hash code or 0 if not computed yet
    */
-  protected abstract int peekCachedHashCode();
+  protected final int peekCachedHashCode() {
+    return hash;
+  }
 
   /**
    * Compute the hash across the value bytes starting with the given hash, and
@@ -1049,8 +1103,49 @@ public abstract class ByteString implements Iterable<Byte>, Serializable {
    */
   protected abstract int partialHash(int h, int offset, int length);
 
+  /**
+   * Checks that the given index falls within the specified array size.
+   *
+   * @param index the index position to be tested
+   * @param size the length of the array
+   * @throws ArrayIndexOutOfBoundsException if the index does not fall within the array.
+   */
+  static void checkIndex(int index, int size) {
+    if ((index | (size - (index + 1))) < 0) {
+      if (index < 0) {
+        throw new ArrayIndexOutOfBoundsException("Index < 0: " + index);
+      }
+      throw new ArrayIndexOutOfBoundsException("Index > length: " + index + ", " + size);
+    }
+  }
+
+  /**
+   * Checks that the given range falls within the bounds of an array
+   *
+   * @param startIndex the start index of the range (inclusive)
+   * @param endIndex the end index of the range (exclusive)
+   * @param size the size of the array.
+   * @return the length of the range.
+   * @throws ArrayIndexOutOfBoundsException some or all of the range falls outside of the array.
+   */
+  static int checkRange(int startIndex, int endIndex, int size) {
+    final int length = endIndex - startIndex;
+    if ((startIndex | endIndex | length | (size - endIndex)) < 0) {
+      if (startIndex < 0) {
+        throw new IndexOutOfBoundsException("Beginning index: " + startIndex + " < 0");
+      }
+      if (endIndex < startIndex) {
+        throw new IndexOutOfBoundsException(
+            "Beginning index larger than ending index: " + startIndex + ", " + endIndex);
+      }
+      // endIndex >= size
+      throw new IndexOutOfBoundsException("End index: " + endIndex + " >= " + size);
+    }
+    return length;
+  }
+
   @Override
-  public String toString() {
+  public final String toString() {
     return String.format("<ByteString@%s size=%d>",
         Integer.toHexString(System.identityHashCode(this)), size());
   }
diff --git a/java/src/main/java/com/google/protobuf/CodedInputStream.java b/java/src/main/java/com/google/protobuf/CodedInputStream.java
index d201f7c5..adc91536 100644
--- a/java/src/main/java/com/google/protobuf/CodedInputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedInputStream.java
@@ -1056,20 +1056,6 @@ public final class CodedInputStream {
   private RefillCallback refillCallback = null;
 
   /**
-   * Ensures that at least {@code n} bytes are available in the buffer, reading
-   * more bytes from the input if necessary to make it so.  Caller must ensure
-   * that the requested space is less than BUFFER_SIZE.
-   *
-   * @throws InvalidProtocolBufferException The end of the stream or the current
-   *                                        limit was reached.
-   */
-  private void ensureAvailable(int n) throws IOException {
-    if (bufferSize - bufferPos < n) {
-      refillBuffer(n);
-    }
-  }
-
-  /**
    * Reads more bytes from the input, making at least {@code n} bytes available
    * in the buffer.  Caller must ensure that the requested space is not yet
    * available, and that the requested space is less than BUFFER_SIZE.
@@ -1180,86 +1166,97 @@ public final class CodedInputStream {
       }
     }
 
-    if (totalBytesRetired + bufferPos + size > currentLimit) {
+    // Verify that the message size so far has not exceeded sizeLimit.
+    int currentMessageSize = totalBytesRetired + bufferPos + size;
+    if (currentMessageSize > sizeLimit) {
+      throw InvalidProtocolBufferException.sizeLimitExceeded();
+    }
+
+    // Verify that the message size so far has not exceeded currentLimit.
+    if (currentMessageSize > currentLimit) {
       // Read to the end of the stream anyway.
       skipRawBytes(currentLimit - totalBytesRetired - bufferPos);
-      // Then fail.
       throw InvalidProtocolBufferException.truncatedMessage();
     }
 
-    if (size < BUFFER_SIZE) {
-      // Reading more bytes than are in the buffer, but not an excessive number
-      // of bytes.  We can safely allocate the resulting array ahead of time.
+    // We need the input stream to proceed.
+    if (input == null) {
+      throw InvalidProtocolBufferException.truncatedMessage();
+    }
+
+    final int originalBufferPos = bufferPos;
+    final int bufferedBytes = bufferSize - bufferPos;
+
+    // Mark the current buffer consumed.
+    totalBytesRetired += bufferSize;
+    bufferPos = 0;
+    bufferSize = 0;
 
-      // First copy what we have.
+    // Determine the number of bytes we need to read from the input stream.
+    int sizeLeft = size - bufferedBytes;
+    // TODO(nathanmittler): Consider using a value larger than BUFFER_SIZE.
+    if (sizeLeft < BUFFER_SIZE || sizeLeft <= input.available()) {
+      // Either the bytes we need are known to be available, or the required buffer is
+      // within an allowed threshold - go ahead and allocate the buffer now.
       final byte[] bytes = new byte[size];
-      int pos = bufferSize - bufferPos;
-      System.arraycopy(buffer, bufferPos, bytes, 0, pos);
-      bufferPos = bufferSize;
 
-      // We want to refill the buffer and then copy from the buffer into our
-      // byte array rather than reading directly into our byte array because
-      // the input may be unbuffered.
-      ensureAvailable(size - pos);
-      System.arraycopy(buffer, 0, bytes, pos, size - pos);
-      bufferPos = size - pos;
+      // Copy all of the buffered bytes to the result buffer.
+      System.arraycopy(buffer, originalBufferPos, bytes, 0, bufferedBytes);
 
-      return bytes;
-    } else {
-      // The size is very large.  For security reasons, we can't allocate the
-      // entire byte array yet.  The size comes directly from the input, so a
-      // maliciously-crafted message could provide a bogus very large size in
-      // order to trick the app into allocating a lot of memory.  We avoid this
-      // by allocating and reading only a small chunk at a time, so that the
-      // malicious message must actually *be* extremely large to cause
-      // problems.  Meanwhile, we limit the allowed size of a message elsewhere.
-
-      // Remember the buffer markers since we'll have to copy the bytes out of
-      // it later.
-      final int originalBufferPos = bufferPos;
-      final int originalBufferSize = bufferSize;
-
-      // Mark the current buffer consumed.
-      totalBytesRetired += bufferSize;
-      bufferPos = 0;
-      bufferSize = 0;
-
-      // Read all the rest of the bytes we need.
-      int sizeLeft = size - (originalBufferSize - originalBufferPos);
-      final List<byte[]> chunks = new ArrayList<byte[]>();
-
-      while (sizeLeft > 0) {
-        final byte[] chunk = new byte[Math.min(sizeLeft, BUFFER_SIZE)];
-        int pos = 0;
-        while (pos < chunk.length) {
-          final int n = (input == null) ? -1 :
-            input.read(chunk, pos, chunk.length - pos);
-          if (n == -1) {
-            throw InvalidProtocolBufferException.truncatedMessage();
-          }
-          totalBytesRetired += n;
-          pos += n;
+      // Fill the remaining bytes from the input stream.
+      int pos = bufferedBytes;
+      while (pos < bytes.length) {
+        int n = input.read(bytes, pos, size - pos);
+        if (n == -1) {
+          throw InvalidProtocolBufferException.truncatedMessage();
         }
-        sizeLeft -= chunk.length;
-        chunks.add(chunk);
+        totalBytesRetired += n;
+        pos += n;
       }
 
-      // OK, got everything.  Now concatenate it all into one buffer.
-      final byte[] bytes = new byte[size];
-
-      // Start by copying the leftover bytes from this.buffer.
-      int pos = originalBufferSize - originalBufferPos;
-      System.arraycopy(buffer, originalBufferPos, bytes, 0, pos);
+      return bytes;
+    }
 
-      // And now all the chunks.
-      for (final byte[] chunk : chunks) {
-        System.arraycopy(chunk, 0, bytes, pos, chunk.length);
-        pos += chunk.length;
+    // The size is very large.  For security reasons, we can't allocate the
+    // entire byte array yet.  The size comes directly from the input, so a
+    // maliciously-crafted message could provide a bogus very large size in
+    // order to trick the app into allocating a lot of memory.  We avoid this
+    // by allocating and reading only a small chunk at a time, so that the
+    // malicious message must actually *be* extremely large to cause
+    // problems.  Meanwhile, we limit the allowed size of a message elsewhere.
+    final List<byte[]> chunks = new ArrayList<byte[]>();
+
+    while (sizeLeft > 0) {
+      // TODO(nathanmittler): Consider using a value larger than BUFFER_SIZE.
+      final byte[] chunk = new byte[Math.min(sizeLeft, BUFFER_SIZE)];
+      int pos = 0;
+      while (pos < chunk.length) {
+        final int n = input.read(chunk, pos, chunk.length - pos);
+        if (n == -1) {
+          throw InvalidProtocolBufferException.truncatedMessage();
+        }
+        totalBytesRetired += n;
+        pos += n;
       }
+      sizeLeft -= chunk.length;
+      chunks.add(chunk);
+    }
 
-      // Done.
-      return bytes;
+    // OK, got everything.  Now concatenate it all into one buffer.
+    final byte[] bytes = new byte[size];
+
+    // Start by copying the leftover bytes from this.buffer.
+    System.arraycopy(buffer, originalBufferPos, bytes, 0, bufferedBytes);
+
+    // And now all the chunks.
+    int pos = bufferedBytes;
+    for (final byte[] chunk : chunks) {
+      System.arraycopy(chunk, 0, bytes, pos, chunk.length);
+      pos += chunk.length;
     }
+
+    // Done.
+    return bytes;
   }
 
   /**
diff --git a/java/src/main/java/com/google/protobuf/CodedOutputStream.java b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
index 291bd20a..d8ebad21 100644
--- a/java/src/main/java/com/google/protobuf/CodedOutputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
@@ -53,7 +53,7 @@ import java.util.logging.Logger;
  * @author kneton@google.com Kenton Varda
  */
 public final class CodedOutputStream {
-  
+
   private static final Logger logger = Logger.getLogger(CodedOutputStream.class.getName());
 
   // TODO(dweis): Consider migrating to a ByteBuffer.
@@ -243,19 +243,6 @@ public final class CodedOutputStream {
   }
 
 
-  /**
-   * Write a group represented by an {@link UnknownFieldSet}.
-   *
-   * @deprecated UnknownFieldSet now implements MessageLite, so you can just
-   *             call {@link #writeGroup}.
-   */
-  @Deprecated
-  public void writeUnknownGroup(final int fieldNumber,
-                                final MessageLite value)
-                                throws IOException {
-    writeGroup(fieldNumber, value);
-  }
-
   /** Write an embedded message field, including tag, to the stream. */
   public void writeMessage(final int fieldNumber, final MessageLite value)
                            throws IOException {
@@ -428,7 +415,7 @@ public final class CodedOutputStream {
     try {
       efficientWriteStringNoTag(value);
     } catch (UnpairedSurrogateException e) {
-      logger.log(Level.WARNING, 
+      logger.log(Level.WARNING,
           "Converting ill-formed UTF-16. Your Protocol Buffer will not round trip correctly!", e);
       inefficientWriteStringNoTag(value);
     }
@@ -449,10 +436,10 @@ public final class CodedOutputStream {
    * Write a {@code string} field to the stream efficiently. If the {@code string} is malformed,
    * this method rolls back its changes and throws an {@link UnpairedSurrogateException} with the
    * intent that the caller will catch and retry with {@link #inefficientWriteStringNoTag(String)}.
-   * 
+   *
    * @param value the string to write to the stream
-   * 
-   * @throws UnpairedSurrogateException when {@code value} is ill-formed UTF-16. 
+   *
+   * @throws UnpairedSurrogateException when {@code value} is ill-formed UTF-16.
    */
   private void efficientWriteStringNoTag(final String value) throws IOException {
     // UTF-8 byte length of the string is at least its UTF-16 code unit length (value.length()),
@@ -510,18 +497,6 @@ public final class CodedOutputStream {
   }
 
 
-  /**
-   * Write a group represented by an {@link UnknownFieldSet}.
-   *
-   * @deprecated UnknownFieldSet now implements MessageLite, so you can just
-   *             call {@link #writeGroupNoTag}.
-   */
-  @Deprecated
-  public void writeUnknownGroupNoTag(final MessageLite value)
-      throws IOException {
-    writeGroupNoTag(value);
-  }
-
   /** Write an embedded message field to the stream. */
   public void writeMessageNoTag(final MessageLite value) throws IOException {
     writeRawVarint32(value.getSerializedSize());
@@ -685,20 +660,6 @@ public final class CodedOutputStream {
   }
 
   /**
-   * Compute the number of bytes that would be needed to encode a
-   * {@code group} field represented by an {@code UnknownFieldSet}, including
-   * tag.
-   *
-   * @deprecated UnknownFieldSet now implements MessageLite, so you can just
-   *             call {@link #computeGroupSize}.
-   */
-  @Deprecated
-  public static int computeUnknownGroupSize(final int fieldNumber,
-                                            final MessageLite value) {
-    return computeGroupSize(fieldNumber, value);
-  }
-
-  /**
    * Compute the number of bytes that would be needed to encode an
    * embedded message field, including tag.
    */
@@ -927,19 +888,6 @@ public final class CodedOutputStream {
   }
 
   /**
-   * Compute the number of bytes that would be needed to encode a
-   * {@code group} field represented by an {@code UnknownFieldSet}, including
-   * tag.
-   *
-   * @deprecated UnknownFieldSet now implements MessageLite, so you can just
-   *             call {@link #computeUnknownGroupSizeNoTag}.
-   */
-  @Deprecated
-  public static int computeUnknownGroupSizeNoTag(final MessageLite value) {
-    return computeGroupSizeNoTag(value);
-  }
-
-  /**
    * Compute the number of bytes that would be needed to encode an embedded
    * message field.
    */
@@ -1295,10 +1243,10 @@ public final class CodedOutputStream {
    * negative.
    */
   public static int computeRawVarint32Size(final int value) {
-    if ((value & (0xffffffff <<  7)) == 0) return 1;
-    if ((value & (0xffffffff << 14)) == 0) return 2;
-    if ((value & (0xffffffff << 21)) == 0) return 3;
-    if ((value & (0xffffffff << 28)) == 0) return 4;
+    if ((value & (~0 <<  7)) == 0) return 1;
+    if ((value & (~0 << 14)) == 0) return 2;
+    if ((value & (~0 << 21)) == 0) return 3;
+    if ((value & (~0 << 28)) == 0) return 4;
     return 5;
   }
 
@@ -1316,17 +1264,16 @@ public final class CodedOutputStream {
   }
 
   /** Compute the number of bytes that would be needed to encode a varint. */
-  public static int computeRawVarint64Size(final long value) {
-    if ((value & (0xffffffffffffffffL <<  7)) == 0) return 1;
-    if ((value & (0xffffffffffffffffL << 14)) == 0) return 2;
-    if ((value & (0xffffffffffffffffL << 21)) == 0) return 3;
-    if ((value & (0xffffffffffffffffL << 28)) == 0) return 4;
-    if ((value & (0xffffffffffffffffL << 35)) == 0) return 5;
-    if ((value & (0xffffffffffffffffL << 42)) == 0) return 6;
-    if ((value & (0xffffffffffffffffL << 49)) == 0) return 7;
-    if ((value & (0xffffffffffffffffL << 56)) == 0) return 8;
-    if ((value & (0xffffffffffffffffL << 63)) == 0) return 9;
-    return 10;
+  public static int computeRawVarint64Size(long value) {
+    // handle two popular special cases up front ...
+    if ((value & (~0L << 7)) == 0L) return 1;
+    if (value < 0L) return 10;
+    // ... leaving us with 8 remaining, which we can divide and conquer
+    int n = 2;
+    if ((value & (~0L << 35)) != 0L) { n += 4; value >>>= 28; }
+    if ((value & (~0L << 21)) != 0L) { n += 2; value >>>= 14; }
+    if ((value & (~0L << 14)) != 0L) { n += 1; }
+    return n;
   }
 
   /** Write a little-endian 32-bit integer. */
diff --git a/java/src/main/java/com/google/protobuf/Descriptors.java b/java/src/main/java/com/google/protobuf/Descriptors.java
index 7cfc47f7..5e15cfbe 100644
--- a/java/src/main/java/com/google/protobuf/Descriptors.java
+++ b/java/src/main/java/com/google/protobuf/Descriptors.java
@@ -889,6 +889,11 @@ public final class Descriptors {
      */
     public String getFullName() { return fullName; }
 
+    /** Get the JSON name of this field. */
+    public String getJsonName() {
+      return jsonName;
+    }
+
     /**
      * Get the field's java type.  This is just for convenience.  Every
      * {@code FieldDescriptorProto.Type} maps to exactly one Java type.
@@ -1079,6 +1084,7 @@ public final class Descriptors {
 
     private FieldDescriptorProto proto;
     private final String fullName;
+    private final String jsonName;
     private final FileDescriptor file;
     private final Descriptor extensionScope;
 
@@ -1157,6 +1163,38 @@ public final class Descriptors {
       private final Object defaultDefault;
     }
 
+    // TODO(xiaofeng): Implement it consistently across different languages. See b/24751348.
+    private static String fieldNameToLowerCamelCase(String name) {
+      StringBuilder result = new StringBuilder(name.length());
+      boolean isNextUpperCase = false;
+      for (int i = 0; i < name.length(); i++) {
+        Character ch = name.charAt(i);
+        if (Character.isLowerCase(ch)) {
+          if (isNextUpperCase) {
+            result.append(Character.toUpperCase(ch));
+          } else {
+            result.append(ch);
+          }
+          isNextUpperCase = false;
+        } else if (Character.isUpperCase(ch)) {
+          if (i == 0) {
+            // Force first letter to lower-case.
+            result.append(Character.toLowerCase(ch));
+          } else {
+            // Capital letters after the first are left as-is.
+            result.append(ch);
+          }
+          isNextUpperCase = false;
+        } else if (Character.isDigit(ch)) {
+          result.append(ch);
+          isNextUpperCase = false;
+        } else {
+          isNextUpperCase = true;
+        }
+      }
+      return result.toString();
+    }
+
     private FieldDescriptor(final FieldDescriptorProto proto,
                             final FileDescriptor file,
                             final Descriptor parent,
@@ -1167,6 +1205,11 @@ public final class Descriptors {
       this.proto = proto;
       fullName = computeFullName(file, parent, proto.getName());
       this.file = file;
+      if (proto.hasJsonName()) {
+        jsonName = proto.getJsonName();
+      } else {
+        jsonName = fieldNameToLowerCamelCase(proto.getName());
+      }
 
       if (proto.hasType()) {
         type = Type.valueOf(proto.getType());
diff --git a/java/src/main/java/com/google/protobuf/DoubleArrayList.java b/java/src/main/java/com/google/protobuf/DoubleArrayList.java
index 90ebe109..bcc9d6ee 100644
--- a/java/src/main/java/com/google/protobuf/DoubleArrayList.java
+++ b/java/src/main/java/com/google/protobuf/DoubleArrayList.java
@@ -68,10 +68,17 @@ final class DoubleArrayList
   private int size;
 
   /**
-   * Constructs a new mutable {@code DoubleArrayList}.
+   * Constructs a new mutable {@code DoubleArrayList} with default capacity.
    */
   DoubleArrayList() {
-    array = new double[DEFAULT_CAPACITY];
+    this(DEFAULT_CAPACITY);
+  }
+
+  /**
+   * Constructs a new mutable {@code DoubleArrayList} with the provided capacity.
+   */
+  DoubleArrayList(int capacity) {
+    array = new double[capacity];
     size = 0;
   }
 
diff --git a/java/src/main/java/com/google/protobuf/FloatArrayList.java b/java/src/main/java/com/google/protobuf/FloatArrayList.java
index 293eaff6..033b5eed 100644
--- a/java/src/main/java/com/google/protobuf/FloatArrayList.java
+++ b/java/src/main/java/com/google/protobuf/FloatArrayList.java
@@ -67,10 +67,17 @@ final class FloatArrayList extends AbstractProtobufList<Float> implements FloatL
   private int size;
 
   /**
-   * Constructs a new mutable {@code FloatArrayList}.
+   * Constructs a new mutable {@code FloatArrayList} with default capacity.
    */
   FloatArrayList() {
-    array = new float[DEFAULT_CAPACITY];
+    this(DEFAULT_CAPACITY);
+  }
+
+  /**
+   * Constructs a new mutable {@code FloatArrayList} with the provided capacity.
+   */
+  FloatArrayList(int capacity) {
+    array = new float[capacity];
     size = 0;
   }
 
diff --git a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
index 4316efee..81e1862c 100644
--- a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
+++ b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
@@ -102,6 +102,11 @@ public abstract class GeneratedMessageLite<
    * @return {@code true} unless the tag is an end-group tag.
    */
   protected boolean parseUnknownField(int tag, CodedInputStream input) throws IOException {
+    // This will avoid the allocation of unknown fields when a group tag is encountered.
+    if (WireFormat.getTagWireType(tag) == WireFormat.WIRETYPE_END_GROUP) {
+      return false;
+    }
+    
     ensureUnknownFieldsInitialized();
     return unknownFields.mergeFieldFrom(tag, input);
   }
@@ -1173,6 +1178,10 @@ public abstract class GeneratedMessageLite<
     return new IntArrayList();
   }
   
+  protected static IntList newIntListWithCapacity(int capacity) {
+    return new IntArrayList(capacity);
+  }
+  
   protected static IntList newIntList(List<Integer> toCopy) {
     return new IntArrayList(toCopy);
   }
@@ -1180,10 +1189,14 @@ public abstract class GeneratedMessageLite<
   protected static IntList emptyIntList() {
     return IntArrayList.emptyList();
   }
-  
+
   protected static LongList newLongList() {
     return new LongArrayList();
   }
+
+  protected static LongList newLongListWithCapacity(int capacity) {
+    return new LongArrayList(capacity);
+  }
   
   protected static LongList newLongList(List<Long> toCopy) {
     return new LongArrayList(toCopy);
@@ -1197,6 +1210,10 @@ public abstract class GeneratedMessageLite<
     return new FloatArrayList();
   }
   
+  protected static FloatList newFloatListWithCapacity(int capacity) {
+    return new FloatArrayList(capacity);
+  }
+  
   protected static FloatList newFloatList(List<Float> toCopy) {
     return new FloatArrayList(toCopy);
   }
@@ -1209,6 +1226,10 @@ public abstract class GeneratedMessageLite<
     return new DoubleArrayList();
   }
   
+  protected static DoubleList newDoubleListWithCapacity(int capacity) {
+    return new DoubleArrayList(capacity);
+  }
+  
   protected static DoubleList newDoubleList(List<Double> toCopy) {
     return new DoubleArrayList(toCopy);
   }
@@ -1221,6 +1242,10 @@ public abstract class GeneratedMessageLite<
     return new BooleanArrayList();
   }
   
+  protected static BooleanList newBooleanListWithCapacity(int capacity) {
+    return new BooleanArrayList(capacity);
+  }
+  
   protected static BooleanList newBooleanList(List<Boolean> toCopy) {
     return new BooleanArrayList(toCopy);
   }
@@ -1237,6 +1262,10 @@ public abstract class GeneratedMessageLite<
     return new ProtobufArrayList<E>(toCopy);
   }
   
+  protected static <E> ProtobufList<E> newProtobufListWithCapacity(int capacity) {
+    return new ProtobufArrayList<E>(capacity);
+  }
+  
   protected static <E> ProtobufList<E> emptyProtobufList() {
     return ProtobufArrayList.emptyList();
   }
diff --git a/java/src/main/java/com/google/protobuf/IntArrayList.java b/java/src/main/java/com/google/protobuf/IntArrayList.java
index f7609cc9..f4e68ed8 100644
--- a/java/src/main/java/com/google/protobuf/IntArrayList.java
+++ b/java/src/main/java/com/google/protobuf/IntArrayList.java
@@ -67,10 +67,17 @@ final class IntArrayList extends AbstractProtobufList<Integer> implements IntLis
   private int size;
 
   /**
-   * Constructs a new mutable {@code IntArrayList}.
+   * Constructs a new mutable {@code IntArrayList} with default capacity.
    */
   IntArrayList() {
-    array = new int[DEFAULT_CAPACITY];
+    this(DEFAULT_CAPACITY);
+  }
+
+  /**
+   * Constructs a new mutable {@code IntArrayList} with the provided capacity.
+   */
+  IntArrayList(int capacity) {
+    array = new int[capacity];
     size = 0;
   }
 
diff --git a/java/src/main/java/com/google/protobuf/LiteralByteString.java b/java/src/main/java/com/google/protobuf/LiteralByteString.java
index c5a8512a..a18c2792 100644
--- a/java/src/main/java/com/google/protobuf/LiteralByteString.java
+++ b/java/src/main/java/com/google/protobuf/LiteralByteString.java
@@ -36,9 +36,8 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
-import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
-import java.util.NoSuchElementException;
 
 /**
  * This class implements a {@link com.google.protobuf.ByteString} backed by a
@@ -49,8 +48,7 @@ import java.util.NoSuchElementException;
  *
  * @author carlanton@google.com (Carl Haverl)
  */
-class LiteralByteString extends ByteString {
-
+class LiteralByteString extends ByteString.LeafByteString {
   private static final long serialVersionUID = 1L;
 
   protected final byte[] bytes;
@@ -82,77 +80,56 @@ class LiteralByteString extends ByteString {
   // ByteString -> substring
 
   @Override
-  public ByteString substring(int beginIndex, int endIndex) {
-    if (beginIndex < 0) {
-      throw new IndexOutOfBoundsException(
-          "Beginning index: " + beginIndex + " < 0");
-    }
-    if (endIndex > size()) {
-      throw new IndexOutOfBoundsException("End index: " + endIndex + " > " +
-          size());
-    }
-    int substringLength = endIndex - beginIndex;
-    if (substringLength < 0) {
-      throw new IndexOutOfBoundsException(
-          "Beginning index larger than ending index: " + beginIndex + ", "
-              + endIndex);
-    }
+  public final ByteString substring(int beginIndex, int endIndex) {
+    final int length = checkRange(beginIndex, endIndex, size());
 
-    ByteString result;
-    if (substringLength == 0) {
-      result = ByteString.EMPTY;
-    } else {
-      result = new BoundedByteString(bytes, getOffsetIntoBytes() + beginIndex,
-          substringLength);
+    if (length == 0) {
+      return ByteString.EMPTY;
     }
-    return result;
+
+    return new BoundedByteString(bytes, getOffsetIntoBytes() + beginIndex, length);
   }
 
   // =================================================================
   // ByteString -> byte[]
 
   @Override
-  protected void copyToInternal(byte[] target, int sourceOffset,
-      int targetOffset, int numberToCopy) {
+  protected void copyToInternal(
+      byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
     // Optimized form, not for subclasses, since we don't call
     // getOffsetIntoBytes() or check the 'numberToCopy' parameter.
+    // TODO(nathanmittler): Is not calling getOffsetIntoBytes really saving that much?
     System.arraycopy(bytes, sourceOffset, target, targetOffset, numberToCopy);
   }
 
   @Override
-  public void copyTo(ByteBuffer target) {
-    target.put(bytes, getOffsetIntoBytes(), size());  // Copies bytes
+  public final void copyTo(ByteBuffer target) {
+    target.put(bytes, getOffsetIntoBytes(), size()); // Copies bytes
+  }
+
+  @Override
+  public final ByteBuffer asReadOnlyByteBuffer() {
+    return ByteBuffer.wrap(bytes, getOffsetIntoBytes(), size()).asReadOnlyBuffer();
   }
 
   @Override
-  public ByteBuffer asReadOnlyByteBuffer() {
-    ByteBuffer byteBuffer =
-        ByteBuffer.wrap(bytes, getOffsetIntoBytes(), size());
-    return byteBuffer.asReadOnlyBuffer();
+  public final List<ByteBuffer> asReadOnlyByteBufferList() {
+    return Collections.singletonList(asReadOnlyByteBuffer());
   }
 
   @Override
-  public List<ByteBuffer> asReadOnlyByteBufferList() {
-    // Return the ByteBuffer generated by asReadOnlyByteBuffer() as a singleton
-    List<ByteBuffer> result = new ArrayList<ByteBuffer>(1);
-    result.add(asReadOnlyByteBuffer());
-    return result;
- }
-
- @Override
-  public void writeTo(OutputStream outputStream) throws IOException {
+  public final void writeTo(OutputStream outputStream) throws IOException {
     outputStream.write(toByteArray());
   }
 
   @Override
-  void writeToInternal(OutputStream outputStream, int sourceOffset,
-      int numberToWrite) throws IOException {
-    outputStream.write(bytes, getOffsetIntoBytes() + sourceOffset,
-        numberToWrite);
+  final void writeToInternal(OutputStream outputStream, int sourceOffset, int numberToWrite)
+      throws IOException {
+    outputStream.write(bytes, getOffsetIntoBytes() + sourceOffset, numberToWrite);
   }
 
   @Override
-  protected String toStringInternal(Charset charset) {
+  protected final String toStringInternal(Charset charset) {
     return new String(bytes, getOffsetIntoBytes(), size(), charset);
   }
 
@@ -160,13 +137,13 @@ class LiteralByteString extends ByteString {
   // UTF-8 decoding
 
   @Override
-  public boolean isValidUtf8() {
+  public final boolean isValidUtf8() {
     int offset = getOffsetIntoBytes();
     return Utf8.isValidUtf8(bytes, offset, offset + size());
   }
 
   @Override
-  protected int partialIsValidUtf8(int state, int offset, int length) {
+  protected final int partialIsValidUtf8(int state, int offset, int length) {
     int index = getOffsetIntoBytes() + offset;
     return Utf8.partialIsValidUtf8(state, bytes, index, index + length);
   }
@@ -175,7 +152,7 @@ class LiteralByteString extends ByteString {
   // equals() and hashCode()
 
   @Override
-  public boolean equals(Object other) {
+  public final boolean equals(Object other) {
     if (other == this) {
       return true;
     }
@@ -194,19 +171,16 @@ class LiteralByteString extends ByteString {
       LiteralByteString otherAsLiteral = (LiteralByteString) other;
       // If we know the hash codes and they are not equal, we know the byte
       // strings are not equal.
-      if (hash != 0
-          && otherAsLiteral.hash != 0
-          && hash != otherAsLiteral.hash) {
+      int thisHash = peekCachedHashCode();
+      int thatHash = otherAsLiteral.peekCachedHashCode();
+      if (thisHash != 0 && thatHash != 0 && thisHash != thatHash) {
         return false;
       }
 
       return equalsRange((LiteralByteString) other, 0, size());
-    } else if (other instanceof RopeByteString) {
-      return other.equals(this);
     } else {
-      throw new IllegalArgumentException(
-          "Has a new type of ByteString been created? Found "
-              + other.getClass());
+      // RopeByteString and NioByteString.
+      return other.equals(this);
     }
   }
 
@@ -219,65 +193,36 @@ class LiteralByteString extends ByteString {
    * @param length number of bytes to compare
    * @return true for equality of substrings, else false.
    */
-  boolean equalsRange(LiteralByteString other, int offset, int length) {
+  @Override
+  final boolean equalsRange(ByteString other, int offset, int length) {
     if (length > other.size()) {
-      throw new IllegalArgumentException(
-          "Length too large: " + length + size());
+      throw new IllegalArgumentException("Length too large: " + length + size());
     }
     if (offset + length > other.size()) {
       throw new IllegalArgumentException(
-          "Ran off end of other: " + offset + ", " + length + ", " +
-              other.size());
+          "Ran off end of other: " + offset + ", " + length + ", " + other.size());
     }
 
-    byte[] thisBytes = bytes;
-    byte[] otherBytes = other.bytes;
-    int thisLimit = getOffsetIntoBytes() + length;
-    for (int thisIndex = getOffsetIntoBytes(), otherIndex =
-        other.getOffsetIntoBytes() + offset;
-        (thisIndex < thisLimit); ++thisIndex, ++otherIndex) {
-      if (thisBytes[thisIndex] != otherBytes[otherIndex]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  /**
-   * Cached hash value.  Intentionally accessed via a data race, which
-   * is safe because of the Java Memory Model's "no out-of-thin-air values"
-   * guarantees for ints.
-   */
-  private int hash = 0;
-
-  /**
-   * Compute the hashCode using the traditional algorithm from {@link
-   * ByteString}.
-   *
-   * @return hashCode value
-   */
-  @Override
-  public int hashCode() {
-    int h = hash;
-
-    if (h == 0) {
-      int size = size();
-      h = partialHash(size, 0, size);
-      if (h == 0) {
-        h = 1;
+    if (other instanceof LiteralByteString) {
+      LiteralByteString lbsOther = (LiteralByteString) other;
+      byte[] thisBytes = bytes;
+      byte[] otherBytes = lbsOther.bytes;
+      int thisLimit = getOffsetIntoBytes() + length;
+      for (
+          int thisIndex = getOffsetIntoBytes(), otherIndex = lbsOther.getOffsetIntoBytes() + offset;
+          (thisIndex < thisLimit); ++thisIndex, ++otherIndex) {
+        if (thisBytes[thisIndex] != otherBytes[otherIndex]) {
+          return false;
+        }
       }
-      hash = h;
+      return true;
     }
-    return h;
-  }
 
-  @Override
-  protected int peekCachedHashCode() {
-    return hash;
+    return other.substring(offset, offset + length).equals(substring(0, length));
   }
 
   @Override
-  protected int partialHash(int h, int offset, int length) {
+  protected final int partialHash(int h, int offset, int length) {
     return hashCode(h, bytes, getOffsetIntoBytes() + offset, length);
   }
 
@@ -297,70 +242,20 @@ class LiteralByteString extends ByteString {
   // Input stream
 
   @Override
-  public InputStream newInput() {
-    return new ByteArrayInputStream(bytes, getOffsetIntoBytes(),
-        size());  // No copy
+  public final InputStream newInput() {
+    return new ByteArrayInputStream(bytes, getOffsetIntoBytes(), size()); // No copy
   }
 
   @Override
-  public CodedInputStream newCodedInput() {
+  public final CodedInputStream newCodedInput() {
     // We trust CodedInputStream not to modify the bytes, or to give anyone
     // else access to them.
     return CodedInputStream.newInstance(this);
   }
 
   // =================================================================
-  // ByteIterator
-
-  @Override
-  public ByteIterator iterator() {
-    return new LiteralByteIterator();
-  }
-
-  private class LiteralByteIterator implements ByteIterator {
-    private int position;
-    private final int limit;
-
-    private LiteralByteIterator() {
-      position = 0;
-      limit = size();
-    }
-
-    public boolean hasNext() {
-      return (position < limit);
-    }
-
-    public Byte next() {
-      // Boxing calls Byte.valueOf(byte), which does not instantiate.
-      return nextByte();
-    }
-
-    public byte nextByte() {
-      try {
-        return bytes[position++];
-      } catch (ArrayIndexOutOfBoundsException e) {
-        throw new NoSuchElementException(e.getMessage());
-      }
-    }
-
-    public void remove() {
-      throw new UnsupportedOperationException();
-    }
-  }
-
-  // =================================================================
   // Internal methods
 
-  @Override
-  protected int getTreeDepth() {
-    return 0;
-  }
-
-  @Override
-  protected boolean isBalanced() {
-    return true;
-  }
-
   /**
    * Offset into {@code bytes[]} to use, non-zero for substrings.
    *
diff --git a/java/src/main/java/com/google/protobuf/LongArrayList.java b/java/src/main/java/com/google/protobuf/LongArrayList.java
index 298617ff..ebe62029 100644
--- a/java/src/main/java/com/google/protobuf/LongArrayList.java
+++ b/java/src/main/java/com/google/protobuf/LongArrayList.java
@@ -67,10 +67,17 @@ final class LongArrayList extends AbstractProtobufList<Long> implements LongList
   private int size;
 
   /**
-   * Constructs a new mutable {@code LongArrayList}.
+   * Constructs a new mutable {@code LongArrayList} with default capacity.
    */
   LongArrayList() {
-    array = new long[DEFAULT_CAPACITY];
+    this(DEFAULT_CAPACITY);
+  }
+
+  /**
+   * Constructs a new mutable {@code LongArrayList} with the provided capacity.
+   */
+  LongArrayList(int capacity) {
+    array = new long[capacity];
     size = 0;
   }
 
diff --git a/java/src/main/java/com/google/protobuf/MapFieldLite.java b/java/src/main/java/com/google/protobuf/MapFieldLite.java
index c17fa7b1..16d3e6d2 100644
--- a/java/src/main/java/com/google/protobuf/MapFieldLite.java
+++ b/java/src/main/java/com/google/protobuf/MapFieldLite.java
@@ -30,6 +30,8 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.Internal.EnumLite;
+
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -44,7 +46,7 @@ import java.util.Set;
  * This class is a protobuf implementation detail. Users shouldn't use this
  * class directly.
  */
-public class MapFieldLite<K, V> implements MutabilityOracle {
+public final class MapFieldLite<K, V> implements MutabilityOracle {
   private MutatabilityAwareMap<K, V> mapData;
   private boolean isMutable;
   
@@ -136,8 +138,9 @@ public class MapFieldLite<K, V> implements MutabilityOracle {
     if (a instanceof byte[]) {
       return LiteralByteString.hashCode((byte[]) a);
     }
-    if (a instanceof Internal.EnumLite) {
-      return Internal.hashEnum((Internal.EnumLite) a);
+    // Enums should be stored as integers internally.
+    if (a instanceof EnumLite) {
+      throw new UnsupportedOperationException();
     }
     return a.hashCode();
   }
diff --git a/java/src/main/java/com/google/protobuf/MessageLiteToString.java b/java/src/main/java/com/google/protobuf/MessageLiteToString.java
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/MessageLiteToString.java
diff --git a/java/src/main/java/com/google/protobuf/NioByteString.java b/java/src/main/java/com/google/protobuf/NioByteString.java
new file mode 100644
index 00000000..f71e41b2
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/NioByteString.java
@@ -0,0 +1,309 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InvalidObjectException;
+import java.io.ObjectInputStream;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.InvalidMarkException;
+import java.nio.channels.Channels;
+import java.nio.charset.Charset;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A {@link ByteString} that wraps around a {@link ByteBuffer}.
+ */
+final class NioByteString extends ByteString.LeafByteString {
+  private final ByteBuffer buffer;
+
+  NioByteString(ByteBuffer buffer) {
+    if (buffer == null) {
+      throw new NullPointerException("buffer");
+    }
+
+    this.buffer = buffer.slice();
+  }
+
+  // =================================================================
+  // Serializable
+
+  /**
+   * Magic method that lets us override serialization behavior.
+   */
+  private Object writeReplace() {
+    return ByteString.copyFrom(buffer.slice());
+  }
+
+  /**
+   * Magic method that lets us override deserialization behavior.
+   */
+  private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws IOException {
+    throw new InvalidObjectException("NioByteString instances are not to be serialized directly");
+  }
+
+  // =================================================================
+
+  @Override
+  public byte byteAt(int index) {
+    try {
+      return buffer.get(index);
+    } catch (ArrayIndexOutOfBoundsException e) {
+      throw e;
+    } catch (IndexOutOfBoundsException e) {
+      throw new ArrayIndexOutOfBoundsException(e.getMessage());
+    }
+  }
+
+  @Override
+  public int size() {
+    return buffer.remaining();
+  }
+
+  @Override
+  public ByteString substring(int beginIndex, int endIndex) {
+    try {
+      ByteBuffer slice = slice(beginIndex, endIndex);
+      return new NioByteString(slice);
+    } catch (ArrayIndexOutOfBoundsException e) {
+      throw e;
+    } catch (IndexOutOfBoundsException e) {
+      throw new ArrayIndexOutOfBoundsException(e.getMessage());
+    }
+  }
+
+  @Override
+  protected void copyToInternal(
+      byte[] target, int sourceOffset, int targetOffset, int numberToCopy) {
+    ByteBuffer slice = buffer.slice();
+    slice.position(sourceOffset);
+    slice.get(target, targetOffset, numberToCopy);
+  }
+
+  @Override
+  public void copyTo(ByteBuffer target) {
+    target.put(buffer.slice());
+  }
+
+  @Override
+  public void writeTo(OutputStream out) throws IOException {
+    writeToInternal(out, buffer.position(), buffer.remaining());
+  }
+
+  @Override
+  boolean equalsRange(ByteString other, int offset, int length) {
+    return substring(0, length).equals(other.substring(offset, offset + length));
+  }
+
+  @Override
+  void writeToInternal(OutputStream out, int sourceOffset, int numberToWrite) throws IOException {
+    if (buffer.hasArray()) {
+      // Optimized write for array-backed buffers.
+      // Note that we're taking the risk that a malicious OutputStream could modify the array.
+      int bufferOffset = buffer.arrayOffset() + buffer.position() + sourceOffset;
+      out.write(buffer.array(), bufferOffset, numberToWrite);
+      return;
+    }
+
+    // Slow path
+    if (out instanceof FileOutputStream || numberToWrite >= 8192) {
+      // Use a channel to write out the ByteBuffer.
+      Channels.newChannel(out).write(slice(sourceOffset, sourceOffset + numberToWrite));
+    } else {
+      // Just copy the data to an array and write it.
+      out.write(toByteArray());
+    }
+  }
+
+  @Override
+  public ByteBuffer asReadOnlyByteBuffer() {
+    return buffer.asReadOnlyBuffer();
+  }
+
+  @Override
+  public List<ByteBuffer> asReadOnlyByteBufferList() {
+    return Collections.singletonList(asReadOnlyByteBuffer());
+  }
+
+  @Override
+  protected String toStringInternal(Charset charset) {
+    byte[] bytes;
+    int offset;
+    if (buffer.hasArray()) {
+      bytes = buffer.array();
+      offset = buffer.arrayOffset() + buffer.position();
+    } else {
+      bytes = toByteArray();
+      offset = 0;
+    }
+    return new String(bytes, offset, size(), charset);
+  }
+
+  @Override
+  public boolean isValidUtf8() {
+    // TODO(nathanmittler): add a ByteBuffer fork for Utf8.isValidUtf8 to avoid the copy
+    byte[] bytes;
+    int startIndex;
+    if (buffer.hasArray()) {
+      bytes = buffer.array();
+      startIndex = buffer.arrayOffset() + buffer.position();
+    } else {
+      bytes = toByteArray();
+      startIndex = 0;
+    }
+    return Utf8.isValidUtf8(bytes, startIndex, startIndex + size());
+  }
+
+  @Override
+  protected int partialIsValidUtf8(int state, int offset, int length) {
+    // TODO(nathanmittler): TODO add a ByteBuffer fork for Utf8.partialIsValidUtf8 to avoid the copy
+    byte[] bytes;
+    int startIndex;
+    if (buffer.hasArray()) {
+      bytes = buffer.array();
+      startIndex = buffer.arrayOffset() + buffer.position();
+    } else {
+      bytes = toByteArray();
+      startIndex = 0;
+    }
+    return Utf8.partialIsValidUtf8(state, bytes, startIndex, startIndex + size());
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (other == this) {
+      return true;
+    }
+    if (!(other instanceof ByteString)) {
+      return false;
+    }
+    ByteString otherString = ((ByteString) other);
+    if (size() != otherString.size()) {
+      return false;
+    }
+    if (size() == 0) {
+      return true;
+    }
+    if (other instanceof NioByteString) {
+      return buffer.equals(((NioByteString) other).buffer);
+    }
+    if (other instanceof RopeByteString) {
+      return other.equals(this);
+    }
+    return buffer.equals(otherString.asReadOnlyByteBuffer());
+  }
+
+  @Override
+  protected int partialHash(int h, int offset, int length) {
+    for (int i = offset; i < offset + length; i++) {
+      h = h * 31 + buffer.get(i);
+    }
+    return h;
+  }
+
+  @Override
+  public InputStream newInput() {
+    return new InputStream() {
+      private final ByteBuffer buf = buffer.slice();
+
+      @Override
+      public void mark(int readlimit) {
+        buf.mark();
+      }
+
+      @Override
+      public boolean markSupported() {
+        return true;
+      }
+
+      @Override
+      public void reset() throws IOException {
+        try {
+          buf.reset();
+        } catch (InvalidMarkException e) {
+          throw new IOException(e);
+        }
+      }
+
+      @Override
+      public int available() throws IOException {
+        return buf.remaining();
+      }
+
+      @Override
+      public int read() throws IOException {
+        if (!buf.hasRemaining()) {
+          return -1;
+        }
+        return buf.get() & 0xFF;
+      }
+
+      @Override
+      public int read(byte[] bytes, int off, int len) throws IOException {
+        if (!buf.hasRemaining()) {
+          return -1;
+        }
+
+        len = Math.min(len, buf.remaining());
+        buf.get(bytes, off, len);
+        return len;
+      }
+    };
+  }
+
+  @Override
+  public CodedInputStream newCodedInput() {
+    return CodedInputStream.newInstance(buffer);
+  }
+
+  /**
+   * Creates a slice of a range of this buffer.
+   *
+   * @param beginIndex the beginning index of the slice (inclusive).
+   * @param endIndex the end index of the slice (exclusive).
+   * @return the requested slice.
+   */
+  private ByteBuffer slice(int beginIndex, int endIndex) {
+    if (beginIndex < buffer.position() || endIndex > buffer.limit() || beginIndex > endIndex) {
+      throw new IllegalArgumentException(
+          String.format("Invalid indices [%d, %d]", beginIndex, endIndex));
+    }
+
+    ByteBuffer slice = buffer.slice();
+    slice.position(beginIndex - buffer.position());
+    slice.limit(endIndex - buffer.position());
+    return slice;
+  }
+}
diff --git a/java/src/main/java/com/google/protobuf/ProtobufArrayList.java b/java/src/main/java/com/google/protobuf/ProtobufArrayList.java
index 759368c9..d2f82ac5 100644
--- a/java/src/main/java/com/google/protobuf/ProtobufArrayList.java
+++ b/java/src/main/java/com/google/protobuf/ProtobufArrayList.java
@@ -60,6 +60,10 @@ class ProtobufArrayList<E> extends AbstractProtobufList<E> {
     list = new ArrayList<E>(toCopy);
   }
   
+  ProtobufArrayList(int capacity) {
+    list = new ArrayList<E>(capacity);
+  }
+  
   @Override
   public void add(int index, E element) {
     ensureIsMutable();
diff --git a/java/src/main/java/com/google/protobuf/RopeByteString.java b/java/src/main/java/com/google/protobuf/RopeByteString.java
index 2c332624..6e8eb724 100644
--- a/java/src/main/java/com/google/protobuf/RopeByteString.java
+++ b/java/src/main/java/com/google/protobuf/RopeByteString.java
@@ -69,7 +69,7 @@ import java.util.Stack;
  *
  * @author carlanton@google.com (Carl Haverl)
  */
-class RopeByteString extends ByteString {
+final class RopeByteString extends ByteString {
 
   /**
    * BAP95. Let Fn be the nth Fibonacci number. A {@link RopeByteString} of
@@ -151,21 +151,24 @@ class RopeByteString extends ByteString {
    * @return concatenation representing the same sequence as the given strings
    */
   static ByteString concatenate(ByteString left, ByteString right) {
-    ByteString result;
-    RopeByteString leftRope =
-        (left instanceof RopeByteString) ? (RopeByteString) left : null;
     if (right.size() == 0) {
-      result = left;
-    } else if (left.size() == 0) {
-      result = right;
-    } else {
-      int newLength = left.size() + right.size();
-      if (newLength < ByteString.CONCATENATE_BY_COPY_SIZE) {
-        // Optimization from BAP95: For short (leaves in paper, but just short
-        // here) total length, do a copy of data to a new leaf.
-        result = concatenateBytes(left, right);
-      } else if (leftRope != null
-          && leftRope.right.size() + right.size() < CONCATENATE_BY_COPY_SIZE) {
+      return left;
+    }
+
+    if (left.size() == 0) {
+      return right;
+    }
+
+    final int newLength = left.size() + right.size();
+    if (newLength < ByteString.CONCATENATE_BY_COPY_SIZE) {
+      // Optimization from BAP95: For short (leaves in paper, but just short
+      // here) total length, do a copy of data to a new leaf.
+      return concatenateBytes(left, right);
+    }
+
+    if (left instanceof RopeByteString) {
+      final RopeByteString leftRope = (RopeByteString) left;
+      if (leftRope.right.size() + right.size() < CONCATENATE_BY_COPY_SIZE) {
         // Optimization from BAP95: As an optimization of the case where the
         // ByteString is constructed by repeated concatenate, recognize the case
         // where a short string is concatenated to a left-hand node whose
@@ -177,9 +180,10 @@ class RopeByteString extends ByteString {
         // new parent node so that the depth of the result is the same as the
         // given left tree.
         ByteString newRight = concatenateBytes(leftRope.right, right);
-        result = new RopeByteString(leftRope.left, newRight);
-      } else if (leftRope != null
-          && leftRope.left.getTreeDepth() > leftRope.right.getTreeDepth()
+        return new RopeByteString(leftRope.left, newRight);
+      }
+
+      if (leftRope.left.getTreeDepth() > leftRope.right.getTreeDepth()
           && leftRope.getTreeDepth() > right.getTreeDepth()) {
         // Typically for concatenate-built strings the left-side is deeper than
         // the right.  This is our final attempt to concatenate without
@@ -187,20 +191,18 @@ class RopeByteString extends ByteString {
         // is yet another optimization for building the string by repeatedly
         // concatenating on the right.
         ByteString newRight = new RopeByteString(leftRope.right, right);
-        result = new RopeByteString(leftRope.left, newRight);
-      } else {
-        // Fine, we'll add a node and increase the tree depth--unless we
-        // rebalance ;^)
-        int newDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1;
-        if (newLength >= minLengthByDepth[newDepth]) {
-          // The tree is shallow enough, so don't rebalance
-          result = new RopeByteString(left, right);
-        } else {
-          result = new Balancer().balance(left, right);
-        }
+        return new RopeByteString(leftRope.left, newRight);
       }
     }
-    return result;
+
+    // Fine, we'll add a node and increase the tree depth--unless we rebalance ;^)
+    int newDepth = Math.max(left.getTreeDepth(), right.getTreeDepth()) + 1;
+    if (newLength >= minLengthByDepth[newDepth]) {
+      // The tree is shallow enough, so don't rebalance
+      return new RopeByteString(left, right);
+    }
+
+    return new Balancer().balance(left, right);
   }
 
   /**
@@ -248,22 +250,14 @@ class RopeByteString extends ByteString {
    */
   @Override
   public byte byteAt(int index) {
-    if (index < 0) {
-      throw new ArrayIndexOutOfBoundsException("Index < 0: " + index);
-    }
-    if (index > totalLength) {
-      throw new ArrayIndexOutOfBoundsException(
-          "Index > length: " + index + ", " + totalLength);
-    }
+    checkIndex(index, totalLength);
 
-    byte result;
     // Find the relevant piece by recursive descent
     if (index < leftLength) {
-      result = left.byteAt(index);
-    } else {
-      result = right.byteAt(index - leftLength);
+      return left.byteAt(index);
     }
-    return result;
+
+    return right.byteAt(index - leftLength);
   }
 
   @Override
@@ -309,48 +303,36 @@ class RopeByteString extends ByteString {
    */
   @Override
   public ByteString substring(int beginIndex, int endIndex) {
-    if (beginIndex < 0) {
-      throw new IndexOutOfBoundsException(
-          "Beginning index: " + beginIndex + " < 0");
+    final int length = checkRange(beginIndex, endIndex, totalLength);
+
+    if (length == 0) {
+      // Empty substring
+      return ByteString.EMPTY;
     }
-    if (endIndex > totalLength) {
-      throw new IndexOutOfBoundsException(
-          "End index: " + endIndex + " > " + totalLength);
+
+    if (length == totalLength) {
+      // The whole string
+      return this;
     }
-    int substringLength = endIndex - beginIndex;
-    if (substringLength < 0) {
-      throw new IndexOutOfBoundsException(
-          "Beginning index larger than ending index: " + beginIndex + ", "
-              + endIndex);
+
+    // Proper substring
+    if (endIndex <= leftLength) {
+      // Substring on the left
+      return left.substring(beginIndex, endIndex);
     }
 
-    ByteString result;
-    if (substringLength == 0) {
-      // Empty substring
-      result = ByteString.EMPTY;
-    } else if (substringLength == totalLength) {
-      // The whole string
-      result = this;
-    } else {
-      // Proper substring
-      if (endIndex <= leftLength) {
-        // Substring on the left
-        result = left.substring(beginIndex, endIndex);
-      } else if (beginIndex >= leftLength) {
-        // Substring on the right
-        result = right
-            .substring(beginIndex - leftLength, endIndex - leftLength);
-      } else {
-        // Split substring
-        ByteString leftSub = left.substring(beginIndex);
-        ByteString rightSub = right.substring(0, endIndex - leftLength);
-        // Intentionally not rebalancing, since in many cases these two
-        // substrings will already be less deep than the top-level
-        // RopeByteString we're taking a substring of.
-        result = new RopeByteString(leftSub, rightSub);
-      }
+    if (beginIndex >= leftLength) {
+      // Substring on the right
+      return right.substring(beginIndex - leftLength, endIndex - leftLength);
     }
-    return result;
+
+    // Split substring
+    ByteString leftSub = left.substring(beginIndex);
+    ByteString rightSub = right.substring(0, endIndex - leftLength);
+    // Intentionally not rebalancing, since in many cases these two
+    // substrings will already be less deep than the top-level
+    // RopeByteString we're taking a substring of.
+    return new RopeByteString(leftSub, rightSub);
   }
 
   // =================================================================
@@ -391,7 +373,7 @@ class RopeByteString extends ByteString {
     List<ByteBuffer> result = new ArrayList<ByteBuffer>();
     PieceIterator pieces = new PieceIterator(this);
     while (pieces.hasNext()) {
-      LiteralByteString byteString = pieces.next();
+      LeafByteString byteString = pieces.next();
       result.add(byteString.asReadOnlyByteBuffer());
     }
     return result;
@@ -471,11 +453,10 @@ class RopeByteString extends ByteString {
     // hashCode if it's already computed.  It's arguable we should compute the
     // hashCode here, and if we're going to be testing a bunch of byteStrings,
     // it might even make sense.
-    if (hash != 0) {
-      int cachedOtherHash = otherByteString.peekCachedHashCode();
-      if (cachedOtherHash != 0 && hash != cachedOtherHash) {
-        return false;
-      }
+    int thisHash = peekCachedHashCode();
+    int thatHash = otherByteString.peekCachedHashCode();
+    if (thisHash != 0 && thatHash != 0 && thisHash != thatHash) {
+      return false;
     }
 
     return equalsFragments(otherByteString);
@@ -492,12 +473,12 @@ class RopeByteString extends ByteString {
    */
   private boolean equalsFragments(ByteString other) {
     int thisOffset = 0;
-    Iterator<LiteralByteString> thisIter = new PieceIterator(this);
-    LiteralByteString thisString = thisIter.next();
+    Iterator<LeafByteString> thisIter = new PieceIterator(this);
+    LeafByteString thisString = thisIter.next();
 
     int thatOffset = 0;
-    Iterator<LiteralByteString> thatIter = new PieceIterator(other);
-    LiteralByteString thatString = thatIter.next();
+    Iterator<LeafByteString> thatIter = new PieceIterator(other);
+    LeafByteString thatString = thatIter.next();
 
     int pos = 0;
     while (true) {
@@ -536,33 +517,6 @@ class RopeByteString extends ByteString {
     }
   }
 
-  /**
-   * Cached hash value.  Intentionally accessed via a data race, which is safe
-   * because of the Java Memory Model's "no out-of-thin-air values" guarantees
-   * for ints.
-   */
-  private int hash = 0;
-
-  @Override
-  public int hashCode() {
-    int h = hash;
-
-    if (h == 0) {
-      h = totalLength;
-      h = partialHash(h, 0, totalLength);
-      if (h == 0) {
-        h = 1;
-      }
-      hash = h;
-    }
-    return h;
-  }
-
-  @Override
-  protected int peekCachedHashCode() {
-    return hash;
-  }
-
   @Override
   protected int partialHash(int h, int offset, int length) {
     int toIndex = offset + length;
@@ -714,34 +668,34 @@ class RopeByteString extends ByteString {
    * <p>This iterator is used to implement
    * {@link RopeByteString#equalsFragments(ByteString)}.
    */
-  private static class PieceIterator implements Iterator<LiteralByteString> {
+  private static class PieceIterator implements Iterator<LeafByteString> {
 
     private final Stack<RopeByteString> breadCrumbs =
         new Stack<RopeByteString>();
-    private LiteralByteString next;
+    private LeafByteString next;
 
     private PieceIterator(ByteString root) {
       next = getLeafByLeft(root);
     }
 
-    private LiteralByteString getLeafByLeft(ByteString root) {
+    private LeafByteString getLeafByLeft(ByteString root) {
       ByteString pos = root;
       while (pos instanceof RopeByteString) {
         RopeByteString rbs = (RopeByteString) pos;
         breadCrumbs.push(rbs);
         pos = rbs.left;
       }
-      return (LiteralByteString) pos;
+      return (LeafByteString) pos;
     }
 
-    private LiteralByteString getNextNonEmptyLeaf() {
+    private LeafByteString getNextNonEmptyLeaf() {
       while (true) {
         // Almost always, we go through this loop exactly once.  However, if
         // we discover an empty string in the rope, we toss it and try again.
         if (breadCrumbs.isEmpty()) {
           return null;
         } else {
-          LiteralByteString result = getLeafByLeft(breadCrumbs.pop().right);
+          LeafByteString result = getLeafByLeft(breadCrumbs.pop().right);
           if (!result.isEmpty()) {
             return result;
           }
@@ -749,6 +703,7 @@ class RopeByteString extends ByteString {
       }
     }
 
+    @Override
     public boolean hasNext() {
       return next != null;
     }
@@ -758,15 +713,17 @@ class RopeByteString extends ByteString {
      *
      * @return next non-empty LiteralByteString or {@code null}
      */
-    public LiteralByteString next() {
+    @Override
+    public LeafByteString next() {
       if (next == null) {
         throw new NoSuchElementException();
       }
-      LiteralByteString result = next;
+      LeafByteString result = next;
       next = getNextNonEmptyLeaf();
       return result;
     }
 
+    @Override
     public void remove() {
       throw new UnsupportedOperationException();
     }
@@ -781,52 +738,11 @@ class RopeByteString extends ByteString {
     return new LiteralByteString(toByteArray());
   }
 
-  private void readObject(ObjectInputStream in) throws IOException {
+  private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws IOException {
     throw new InvalidObjectException(
         "RopeByteStream instances are not to be serialized directly");
   }
 
-  // =================================================================
-  // ByteIterator
-
-  @Override
-  public ByteIterator iterator() {
-    return new RopeByteIterator();
-  }
-
-  private class RopeByteIterator implements ByteString.ByteIterator {
-
-    private final PieceIterator pieces;
-    private ByteIterator bytes;
-    int bytesRemaining;
-
-    private RopeByteIterator() {
-      pieces = new PieceIterator(RopeByteString.this);
-      bytes = pieces.next().iterator();
-      bytesRemaining = size();
-    }
-
-    public boolean hasNext() {
-      return (bytesRemaining > 0);
-    }
-
-    public Byte next() {
-      return nextByte(); // Does not instantiate a Byte
-    }
-
-    public byte nextByte() {
-      if (!bytes.hasNext()) {
-        bytes = pieces.next().iterator();
-      }
-      --bytesRemaining;
-      return bytes.nextByte();
-    }
-
-    public void remove() {
-      throw new UnsupportedOperationException();
-    }
-  }
-
   /**
    * This class is the {@link RopeByteString} equivalent for
    * {@link ByteArrayInputStream}.
@@ -835,7 +751,7 @@ class RopeByteString extends ByteString {
     // Iterates through the pieces of the rope
     private PieceIterator pieceIterator;
     // The current piece
-    private LiteralByteString currentPiece;
+    private LeafByteString currentPiece;
     // The size of the current piece
     private int currentPieceSize;
     // The index of the next byte to read in the current piece
@@ -872,7 +788,7 @@ class RopeByteString extends ByteString {
     /**
      * Internal implementation of read and skip.  If b != null, then read the
      * next {@code length} bytes into the buffer {@code b} at
-     * offset {@code offset}.  If b == null, then skip the next {@code length)
+     * offset {@code offset}.  If b == null, then skip the next {@code length}
      * bytes.
      * <p>
      * This method assumes that all error checking has already happened.
diff --git a/java/src/main/java/com/google/protobuf/TextFormat.java b/java/src/main/java/com/google/protobuf/TextFormat.java
index 44d036c1..c99b5285 100644
--- a/java/src/main/java/com/google/protobuf/TextFormat.java
+++ b/java/src/main/java/com/google/protobuf/TextFormat.java
@@ -1074,6 +1074,18 @@ public final class TextFormat {
     private ParseException floatParseException(final NumberFormatException e) {
       return parseException("Couldn't parse number: " + e.getMessage());
     }
+    
+    /**
+     * Returns a {@link UnknownFieldParseException} with the line and column
+     * numbers of the previous token in the description, and the unknown field
+     * name, suitable for throwing.
+     */
+    public UnknownFieldParseException unknownFieldParseExceptionPreviousToken(
+        final String unknownField, final String description) {
+      // Note:  People generally prefer one-based line and column numbers.
+      return new UnknownFieldParseException(
+        previousLine + 1, previousColumn + 1, unknownField, description);
+    }
   }
 
   /** Thrown when parsing an invalid text format message. */
@@ -1121,6 +1133,45 @@ public final class TextFormat {
       return column;
     }
   }
+  
+  /**
+   * Thrown when encountering an unknown field while parsing
+   * a text format message.
+   */
+  public static class UnknownFieldParseException extends ParseException {
+    private final String unknownField;
+
+    /**
+     * Create a new instance, with -1 as the line and column numbers, and an
+     * empty unknown field name.
+     */
+    public UnknownFieldParseException(final String message) {
+      this(-1, -1, "", message);
+    }
+
+    /**
+     * Create a new instance
+     *
+     * @param line the line number where the parse error occurred,
+     * using 1-offset.
+     * @param column the column number where the parser error occurred,
+     * using 1-offset.
+     * @param unknownField the name of the unknown field found while parsing.
+     */
+    public UnknownFieldParseException(final int line, final int column,
+        final String unknownField, final String message) {
+      super(line, column, message);
+      this.unknownField = unknownField;
+    }
+
+    /**
+     * Return the name of the unknown field encountered while parsing the
+     * protocol buffer string.
+     */
+    public String getUnknownField() {
+      return unknownField;
+    }
+  }
 
   private static final Parser PARSER = Parser.newBuilder().build();
 
@@ -1388,7 +1439,8 @@ public final class TextFormat {
 
         if (field == null) {
           if (!allowUnknownFields) {
-            throw tokenizer.parseExceptionPreviousToken(
+            throw tokenizer.unknownFieldParseExceptionPreviousToken(
+              name,
               "Message type \"" + type.getFullName()
               + "\" has no field named \"" + name + "\".");
           } else {
diff --git a/java/src/main/java/com/google/protobuf/TextFormatEscaper.java b/java/src/main/java/com/google/protobuf/TextFormatEscaper.java
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/TextFormatEscaper.java
diff --git a/java/src/main/java/com/google/protobuf/UnsafeByteStrings.java b/java/src/main/java/com/google/protobuf/UnsafeByteStrings.java
new file mode 100644
index 00000000..c1997515
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/UnsafeByteStrings.java
@@ -0,0 +1,55 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.nio.ByteBuffer;
+
+/**
+ * Provides unsafe factory methods for {@link ByteString} instances.
+ *
+ * <p><strong>DISCLAIMER:</strong> The methods in this class should only be called if it is
+ * guaranteed that the the buffer backing the {@link ByteString} will never change! Mutation of a
+ * {@link ByteString} can lead to unexpected and undesirable consequences in your application,
+ * and will likely be difficult to debug. Proceed with caution!
+ */
+public final class UnsafeByteStrings {
+  private UnsafeByteStrings() {}
+
+  /**
+   * An unsafe operation that returns a {@link ByteString} that is backed by the provided buffer.
+   *
+   * @param buffer the Java NIO buffer to be wrapped.
+   * @return a {@link ByteString} backed by the provided buffer.
+   */
+  public static ByteString unsafeWrap(ByteBuffer buffer) {
+    return new NioByteString(buffer);
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/BooleanArrayListTest.java b/java/src/test/java/com/google/protobuf/BooleanArrayListTest.java
index df89c263..b8ad1fe4 100644
--- a/java/src/test/java/com/google/protobuf/BooleanArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/BooleanArrayListTest.java
@@ -310,10 +310,6 @@ public class BooleanArrayListTest extends TestCase {
   }
   
   private void assertImmutable(BooleanArrayList list) {
-    if (list.contains(1)) {
-      throw new RuntimeException("Cannot test the immutability of lists that contain 1.");
-    }
-    
     try {
       list.add(false);
       fail();
@@ -413,7 +409,7 @@ public class BooleanArrayListTest extends TestCase {
     }
     
     try {
-      list.removeAll(Collections.singleton(1));
+      list.removeAll(Collections.singleton(Boolean.TRUE));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
@@ -434,7 +430,7 @@ public class BooleanArrayListTest extends TestCase {
     }
     
     try {
-      list.retainAll(Collections.singleton(1));
+      list.retainAll(Collections.singleton(Boolean.TRUE));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
diff --git a/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java b/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java
index 447e6ef3..2dfae2e6 100644
--- a/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java
+++ b/java/src/test/java/com/google/protobuf/BoundedByteStringTest.java
@@ -73,7 +73,7 @@ public class BoundedByteStringTest extends LiteralByteStringTest {
   }
 
   @Override
-  public void testCharsetToString() throws UnsupportedEncodingException {
+  public void testCharsetToString() {
     String testString = "I love unicode \u1234\u5678 characters";
     LiteralByteString unicode = new LiteralByteString(testString.getBytes(Internal.UTF_8));
     ByteString chopped = unicode.substring(2, unicode.size() - 6);
diff --git a/java/src/test/java/com/google/protobuf/ByteStringTest.java b/java/src/test/java/com/google/protobuf/ByteStringTest.java
index 8af5dcde..36f64251 100644
--- a/java/src/test/java/com/google/protobuf/ByteStringTest.java
+++ b/java/src/test/java/com/google/protobuf/ByteStringTest.java
@@ -39,7 +39,6 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
@@ -129,7 +128,7 @@ public class ByteStringTest extends TestCase {
         isArrayRange(byteString.toByteArray(), bytes, 500, bytes.length - 500));
   }
 
-  public void testCopyFrom_StringEncoding() throws UnsupportedEncodingException {
+  public void testCopyFrom_StringEncoding() {
     String testString = "I love unicode \u1234\u5678 characters";
     ByteString byteString = ByteString.copyFrom(testString, UTF_16);
     byte[] testBytes = testString.getBytes(UTF_16);
@@ -137,7 +136,7 @@ public class ByteStringTest extends TestCase {
         isArrayRange(byteString.toByteArray(), testBytes, 0, testBytes.length));
   }
 
-  public void testCopyFrom_Utf8() throws UnsupportedEncodingException {
+  public void testCopyFrom_Utf8() {
     String testString = "I love unicode \u1234\u5678 characters";
     ByteString byteString = ByteString.copyFromUtf8(testString);
     byte[] testBytes = testString.getBytes(Internal.UTF_8);
@@ -154,6 +153,7 @@ public class ByteStringTest extends TestCase {
         isArrayRange(byteString.toByteArray(), testBytes, 0, testBytes.length));
     // Call copyFrom on an iteration that's not a collection
     ByteString byteStringAlt = ByteString.copyFrom(new Iterable<ByteString>() {
+      @Override
       public Iterator<ByteString> iterator() {
         return pieces.iterator();
       }
@@ -399,7 +399,7 @@ public class ByteStringTest extends TestCase {
     }
   }
 
-  public void testToStringUtf8() throws UnsupportedEncodingException {
+  public void testToStringUtf8() {
     String testString = "I love unicode \u1234\u5678 characters";
     byte[] testBytes = testString.getBytes(Internal.UTF_8);
     ByteString byteString = ByteString.copyFrom(testBytes);
@@ -419,7 +419,7 @@ public class ByteStringTest extends TestCase {
 
   // Test newOutput() using a variety of buffer sizes and a variety of (fixed)
   // write sizes
-  public void testNewOutput_ArrayWrite() throws IOException {
+  public void testNewOutput_ArrayWrite() {
     byte[] bytes = getTestBytes();
     int length = bytes.length;
     int[] bufferSizes = {128, 256, length / 2, length - 1, length, length + 1,
@@ -442,7 +442,7 @@ public class ByteStringTest extends TestCase {
 
   // Test newOutput() using a variety of buffer sizes, but writing all the
   // characters using write(byte);
-  public void testNewOutput_WriteChar() throws IOException {
+  public void testNewOutput_WriteChar() {
     byte[] bytes = getTestBytes();
     int length = bytes.length;
     int[] bufferSizes = {0, 1, 128, 256, length / 2,
@@ -461,7 +461,7 @@ public class ByteStringTest extends TestCase {
 
   // Test newOutput() in which we write the bytes using a variety of methods
   // and sizes, and in which we repeatedly call toByteString() in the middle.
-  public void testNewOutput_Mixed() throws IOException {
+  public void testNewOutput_Mixed() {
     Random rng = new Random(1);
     byte[] bytes = getTestBytes();
     int length = bytes.length;
@@ -494,7 +494,7 @@ public class ByteStringTest extends TestCase {
     }
   }
 
-  public void testNewOutputEmpty() throws IOException {
+  public void testNewOutputEmpty() {
     // Make sure newOutput() correctly builds empty byte strings
     ByteString byteString = ByteString.newOutput().toByteString();
     assertEquals(ByteString.EMPTY, byteString);
diff --git a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
index 360e759e..6018ea55 100644
--- a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
+++ b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
@@ -37,6 +37,7 @@ import protobuf_unittest.UnittestProto.TestSparseEnum;
 
 import junit.framework.TestCase;
 
+import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
@@ -80,8 +81,8 @@ public class CodedOutputStreamTest extends TestCase {
    * checks that the result matches the given bytes.
    */
   private void assertWriteVarint(byte[] data, long value) throws Exception {
-    // Only do 32-bit write if the value fits in 32 bits.
-    if ((value >>> 32) == 0) {
+    // Only test 32-bit write if the value fits into an int.
+    if (value == (int) value) {
       ByteArrayOutputStream rawOutput = new ByteArrayOutputStream();
       CodedOutputStream output = CodedOutputStream.newInstance(rawOutput);
       output.writeRawVarint32((int) value);
@@ -107,8 +108,8 @@ public class CodedOutputStreamTest extends TestCase {
 
     // Try different block sizes.
     for (int blockSize = 1; blockSize <= 16; blockSize *= 2) {
-      // Only do 32-bit write if the value fits in 32 bits.
-      if ((value >>> 32) == 0) {
+      // Only test 32-bit write if the value fits into an int.
+      if (value == (int) value) {
         ByteArrayOutputStream rawOutput = new ByteArrayOutputStream();
         CodedOutputStream output =
           CodedOutputStream.newInstance(rawOutput, blockSize);
@@ -128,6 +129,42 @@ public class CodedOutputStreamTest extends TestCase {
     }
   }
 
+  private void assertVarintRoundTrip(long value) throws Exception {
+    {
+      ByteArrayOutputStream rawOutput = new ByteArrayOutputStream();
+      CodedOutputStream output = CodedOutputStream.newInstance(rawOutput);
+      output.writeRawVarint64(value);
+      output.flush();
+      byte[] bytes = rawOutput.toByteArray();
+      assertEquals(bytes.length, CodedOutputStream.computeRawVarint64Size(value));
+      CodedInputStream input = CodedInputStream.newInstance(new ByteArrayInputStream(bytes));
+      assertEquals(value, input.readRawVarint64());
+    }
+
+    if (value == (int) value) {
+      ByteArrayOutputStream rawOutput = new ByteArrayOutputStream();
+      CodedOutputStream output = CodedOutputStream.newInstance(rawOutput);
+      output.writeRawVarint32((int) value);
+      output.flush();
+      byte[] bytes = rawOutput.toByteArray();
+      assertEquals(bytes.length, CodedOutputStream.computeRawVarint32Size((int) value));
+      CodedInputStream input = CodedInputStream.newInstance(new ByteArrayInputStream(bytes));
+      assertEquals(value, input.readRawVarint32());
+    }
+  }
+
+  /** Checks that invariants are maintained for varint round trip input and output. */
+  public void testVarintRoundTrips() throws Exception {
+    assertVarintRoundTrip(0L);
+    for (int bits = 0; bits < 64; bits++) {
+      long value = 1L << bits;
+      assertVarintRoundTrip(value);
+      assertVarintRoundTrip(value + 1);
+      assertVarintRoundTrip(value - 1);
+      assertVarintRoundTrip(-value);
+    }
+  }
+
   /** Tests writeRawVarint32() and writeRawVarint64(). */
   public void testWriteVarint() throws Exception {
     assertWriteVarint(bytes(0x00), 0);
diff --git a/java/src/test/java/com/google/protobuf/DescriptorsTest.java b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
index 30da2487..82ff34af 100644
--- a/java/src/test/java/com/google/protobuf/DescriptorsTest.java
+++ b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
@@ -274,6 +274,15 @@ public class DescriptorsTest extends TestCase {
     assertFalse(repeatedField.isRequired());
     assertTrue(repeatedField.isRepeated());
   }
+  
+  public void testFieldDescriptorJsonName() throws Exception {
+    FieldDescriptor requiredField = TestRequired.getDescriptor().findFieldByName("a");
+    FieldDescriptor optionalField = TestAllTypes.getDescriptor().findFieldByName("optional_int32");
+    FieldDescriptor repeatedField = TestAllTypes.getDescriptor().findFieldByName("repeated_int32");
+    assertEquals("a", requiredField.getJsonName());
+    assertEquals("optionalInt32", optionalField.getJsonName());
+    assertEquals("repeatedInt32", repeatedField.getJsonName());
+  }
 
   public void testFieldDescriptorDefault() throws Exception {
     Descriptor d = TestAllTypes.getDescriptor();
diff --git a/java/src/test/java/com/google/protobuf/DoubleArrayListTest.java b/java/src/test/java/com/google/protobuf/DoubleArrayListTest.java
index e7a73d70..d3deaa07 100644
--- a/java/src/test/java/com/google/protobuf/DoubleArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/DoubleArrayListTest.java
@@ -310,7 +310,7 @@ public class DoubleArrayListTest extends TestCase {
   }
   
   private void assertImmutable(DoubleArrayList list) {
-    if (list.contains(1)) {
+    if (list.contains(1D)) {
       throw new RuntimeException("Cannot test the immutability of lists that contain 1.");
     }
     
@@ -413,7 +413,7 @@ public class DoubleArrayListTest extends TestCase {
     }
     
     try {
-      list.removeAll(Collections.singleton(1));
+      list.removeAll(Collections.singleton(1D));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
@@ -434,7 +434,7 @@ public class DoubleArrayListTest extends TestCase {
     }
     
     try {
-      list.retainAll(Collections.singleton(1));
+      list.retainAll(Collections.singleton(1D));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
diff --git a/java/src/test/java/com/google/protobuf/FloatArrayListTest.java b/java/src/test/java/com/google/protobuf/FloatArrayListTest.java
index 8f3e93dc..a5e65424 100644
--- a/java/src/test/java/com/google/protobuf/FloatArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/FloatArrayListTest.java
@@ -310,7 +310,7 @@ public class FloatArrayListTest extends TestCase {
   }
   
   private void assertImmutable(FloatArrayList list) {
-    if (list.contains(1)) {
+    if (list.contains(1F)) {
       throw new RuntimeException("Cannot test the immutability of lists that contain 1.");
     }
     
@@ -413,7 +413,7 @@ public class FloatArrayListTest extends TestCase {
     }
     
     try {
-      list.removeAll(Collections.singleton(1));
+      list.removeAll(Collections.singleton(1F));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
@@ -434,7 +434,7 @@ public class FloatArrayListTest extends TestCase {
     }
     
     try {
-      list.retainAll(Collections.singleton(1));
+      list.retainAll(Collections.singleton(1F));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
diff --git a/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java b/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java
index 7dfda2ae..c8495633 100644
--- a/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java
+++ b/java/src/test/java/com/google/protobuf/LiteralByteStringTest.java
@@ -355,7 +355,7 @@ public class LiteralByteStringTest extends TestCase {
     assertEquals(classUnderTest + " unicode must match", testString, roundTripString);
   }
 
-  public void testCharsetToString() throws UnsupportedEncodingException {
+  public void testCharsetToString() {
     String testString = "I love unicode \u1234\u5678 characters";
     LiteralByteString unicode = new LiteralByteString(testString.getBytes(Internal.UTF_8));
     String roundTripString = unicode.toString(Internal.UTF_8);
diff --git a/java/src/test/java/com/google/protobuf/LongArrayListTest.java b/java/src/test/java/com/google/protobuf/LongArrayListTest.java
index 3a52ec7f..1bd094f7 100644
--- a/java/src/test/java/com/google/protobuf/LongArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/LongArrayListTest.java
@@ -310,7 +310,7 @@ public class LongArrayListTest extends TestCase {
   }
   
   private void assertImmutable(LongArrayList list) {
-    if (list.contains(1)) {
+    if (list.contains(1L)) {
       throw new RuntimeException("Cannot test the immutability of lists that contain 1.");
     }
     
@@ -413,7 +413,7 @@ public class LongArrayListTest extends TestCase {
     }
     
     try {
-      list.removeAll(Collections.singleton(1));
+      list.removeAll(Collections.singleton(1L));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
@@ -434,7 +434,7 @@ public class LongArrayListTest extends TestCase {
     }
     
     try {
-      list.retainAll(Collections.singleton(1));
+      list.retainAll(Collections.singleton(1L));
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
diff --git a/java/src/test/java/com/google/protobuf/NioByteStringTest.java b/java/src/test/java/com/google/protobuf/NioByteStringTest.java
new file mode 100644
index 00000000..0679937f
--- /dev/null
+++ b/java/src/test/java/com/google/protobuf/NioByteStringTest.java
@@ -0,0 +1,546 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import static com.google.protobuf.Internal.UTF_8;
+
+import junit.framework.TestCase;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.UnsupportedEncodingException;
+import java.nio.BufferOverflowException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+/**
+ * Tests for {@link NioByteString}.
+ */
+public class NioByteStringTest extends TestCase {
+  private static final ByteString EMPTY = UnsafeByteStrings.unsafeWrap(
+      ByteBuffer.wrap(new byte[0]));
+  private static final String CLASSNAME = NioByteString.class.getSimpleName();
+  private static final byte[] BYTES = ByteStringTest.getTestBytes(1234, 11337766L);
+  private static final int EXPECTED_HASH = new LiteralByteString(BYTES).hashCode();
+  private static final ByteBuffer BUFFER = ByteBuffer.wrap(BYTES.clone());
+  private static final ByteString TEST_STRING = UnsafeByteStrings.unsafeWrap(BUFFER);
+
+  public void testExpectedType() {
+    String actualClassName = getActualClassName(TEST_STRING);
+    assertEquals(CLASSNAME + " should match type exactly", CLASSNAME, actualClassName);
+  }
+
+  protected String getActualClassName(Object object) {
+    String actualClassName = object.getClass().getName();
+    actualClassName = actualClassName.substring(actualClassName.lastIndexOf('.') + 1);
+    return actualClassName;
+  }
+
+  public void testByteAt() {
+    boolean stillEqual = true;
+    for (int i = 0; stillEqual && i < BYTES.length; ++i) {
+      stillEqual = (BYTES[i] == TEST_STRING.byteAt(i));
+    }
+    assertTrue(CLASSNAME + " must capture the right bytes", stillEqual);
+  }
+
+  public void testByteIterator() {
+    boolean stillEqual = true;
+    ByteString.ByteIterator iter = TEST_STRING.iterator();
+    for (int i = 0; stillEqual && i < BYTES.length; ++i) {
+      stillEqual = (iter.hasNext() && BYTES[i] == iter.nextByte());
+    }
+    assertTrue(CLASSNAME + " must capture the right bytes", stillEqual);
+    assertFalse(CLASSNAME + " must have exhausted the itertor", iter.hasNext());
+
+    try {
+      iter.nextByte();
+      fail("Should have thrown an exception.");
+    } catch (NoSuchElementException e) {
+      // This is success
+    }
+  }
+
+  public void testByteIterable() {
+    boolean stillEqual = true;
+    int j = 0;
+    for (byte quantum : TEST_STRING) {
+      stillEqual = (BYTES[j] == quantum);
+      ++j;
+    }
+    assertTrue(CLASSNAME + " must capture the right bytes as Bytes", stillEqual);
+    assertEquals(CLASSNAME + " iterable character count", BYTES.length, j);
+  }
+
+  public void testSize() {
+    assertEquals(CLASSNAME + " must have the expected size", BYTES.length,
+        TEST_STRING.size());
+  }
+
+  public void testGetTreeDepth() {
+    assertEquals(CLASSNAME + " must have depth 0", 0, TEST_STRING.getTreeDepth());
+  }
+
+  public void testIsBalanced() {
+    assertTrue(CLASSNAME + " is technically balanced", TEST_STRING.isBalanced());
+  }
+
+  public void testCopyTo_ByteArrayOffsetLength() {
+    int destinationOffset = 50;
+    int length = 100;
+    byte[] destination = new byte[destinationOffset + length];
+    int sourceOffset = 213;
+    TEST_STRING.copyTo(destination, sourceOffset, destinationOffset, length);
+    boolean stillEqual = true;
+    for (int i = 0; stillEqual && i < length; ++i) {
+      stillEqual = BYTES[i + sourceOffset] == destination[i + destinationOffset];
+    }
+    assertTrue(CLASSNAME + ".copyTo(4 arg) must give the expected bytes", stillEqual);
+  }
+
+  public void testCopyTo_ByteArrayOffsetLengthErrors() {
+    int destinationOffset = 50;
+    int length = 100;
+    byte[] destination = new byte[destinationOffset + length];
+
+    try {
+      // Copy one too many bytes
+      TEST_STRING.copyTo(destination, TEST_STRING.size() + 1 - length,
+          destinationOffset, length);
+      fail("Should have thrown an exception when copying too many bytes of a "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative sourceOffset
+      TEST_STRING.copyTo(destination, -1, destinationOffset, length);
+      fail("Should have thrown an exception when given a negative sourceOffset in "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative destinationOffset
+      TEST_STRING.copyTo(destination, 0, -1, length);
+      fail("Should have thrown an exception when given a negative destinationOffset in "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal negative size
+      TEST_STRING.copyTo(destination, 0, 0, -1);
+      fail("Should have thrown an exception when given a negative size in "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal too-large sourceOffset
+      TEST_STRING.copyTo(destination, 2 * TEST_STRING.size(), 0, length);
+      fail("Should have thrown an exception when the destinationOffset is too large in "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+
+    try {
+      // Copy with illegal too-large destinationOffset
+      TEST_STRING.copyTo(destination, 0, 2 * destination.length, length);
+      fail("Should have thrown an exception when the destinationOffset is too large in "
+          + CLASSNAME);
+    } catch (IndexOutOfBoundsException expected) {
+      // This is success
+    }
+  }
+
+  public void testCopyTo_ByteBuffer() {
+    // Same length.
+    ByteBuffer myBuffer = ByteBuffer.allocate(BYTES.length);
+    TEST_STRING.copyTo(myBuffer);
+    myBuffer.flip();
+    assertEquals(CLASSNAME + ".copyTo(ByteBuffer) must give back the same bytes",
+        BUFFER, myBuffer);
+
+    // Target buffer bigger than required.
+    myBuffer = ByteBuffer.allocate(TEST_STRING.size() + 1);
+    TEST_STRING.copyTo(myBuffer);
+    myBuffer.flip();
+    assertEquals(BUFFER, myBuffer);
+
+    // Target buffer has no space.
+    myBuffer = ByteBuffer.allocate(0);
+    try {
+      TEST_STRING.copyTo(myBuffer);
+      fail("Should have thrown an exception when target ByteBuffer has insufficient capacity");
+    } catch (BufferOverflowException e) {
+      // Expected.
+    }
+
+    // Target buffer too small.
+    myBuffer = ByteBuffer.allocate(1);
+    try {
+      TEST_STRING.copyTo(myBuffer);
+      fail("Should have thrown an exception when target ByteBuffer has insufficient capacity");
+    } catch (BufferOverflowException e) {
+      // Expected.
+    }
+  }
+
+  public void testMarkSupported() {
+    InputStream stream = TEST_STRING.newInput();
+    assertTrue(CLASSNAME + ".newInput() must support marking", stream.markSupported());
+  }
+
+  public void testMarkAndReset() throws IOException {
+    int fraction = TEST_STRING.size() / 3;
+
+    InputStream stream = TEST_STRING.newInput();
+    stream.mark(TEST_STRING.size()); // First, mark() the end.
+
+    skipFully(stream, fraction); // Skip a large fraction, but not all.
+    assertEquals(
+        CLASSNAME + ": after skipping to the 'middle', half the bytes are available",
+        (TEST_STRING.size() - fraction), stream.available());
+    stream.reset();
+    assertEquals(
+        CLASSNAME + ": after resetting, all bytes are available",
+        TEST_STRING.size(), stream.available());
+
+    skipFully(stream, TEST_STRING.size()); // Skip to the end.
+    assertEquals(
+        CLASSNAME + ": after skipping to the end, no more bytes are available",
+        0, stream.available());
+  }
+
+  /**
+   * Discards {@code n} bytes of data from the input stream. This method
+   * will block until the full amount has been skipped. Does not close the
+   * stream.
+   * <p>Copied from com.google.common.io.ByteStreams to avoid adding dependency.
+   *
+   * @param in the input stream to read from
+   * @param n the number of bytes to skip
+   * @throws EOFException if this stream reaches the end before skipping all
+   *     the bytes
+   * @throws IOException if an I/O error occurs, or the stream does not
+   *     support skipping
+   */
+  static void skipFully(InputStream in, long n) throws IOException {
+    long toSkip = n;
+    while (n > 0) {
+      long amt = in.skip(n);
+      if (amt == 0) {
+        // Force a blocking read to avoid infinite loop
+        if (in.read() == -1) {
+          long skipped = toSkip - n;
+          throw new EOFException("reached end of stream after skipping "
+              + skipped + " bytes; " + toSkip + " bytes expected");
+        }
+        n--;
+      } else {
+        n -= amt;
+      }
+    }
+  }
+
+  public void testAsReadOnlyByteBuffer() {
+    ByteBuffer byteBuffer = TEST_STRING.asReadOnlyByteBuffer();
+    byte[] roundTripBytes = new byte[BYTES.length];
+    assertTrue(byteBuffer.remaining() == BYTES.length);
+    assertTrue(byteBuffer.isReadOnly());
+    byteBuffer.get(roundTripBytes);
+    assertTrue(CLASSNAME + ".asReadOnlyByteBuffer() must give back the same bytes",
+        Arrays.equals(BYTES, roundTripBytes));
+  }
+
+  public void testAsReadOnlyByteBufferList() {
+    List<ByteBuffer> byteBuffers = TEST_STRING.asReadOnlyByteBufferList();
+    int bytesSeen = 0;
+    byte[] roundTripBytes = new byte[BYTES.length];
+    for (ByteBuffer byteBuffer : byteBuffers) {
+      int thisLength = byteBuffer.remaining();
+      assertTrue(byteBuffer.isReadOnly());
+      assertTrue(bytesSeen + thisLength <= BYTES.length);
+      byteBuffer.get(roundTripBytes, bytesSeen, thisLength);
+      bytesSeen += thisLength;
+    }
+    assertTrue(bytesSeen == BYTES.length);
+    assertTrue(CLASSNAME + ".asReadOnlyByteBufferTest() must give back the same bytes",
+        Arrays.equals(BYTES, roundTripBytes));
+  }
+
+  public void testToByteArray() {
+    byte[] roundTripBytes = TEST_STRING.toByteArray();
+    assertTrue(CLASSNAME + ".toByteArray() must give back the same bytes",
+        Arrays.equals(BYTES, roundTripBytes));
+  }
+
+  public void testWriteTo() throws IOException {
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+    TEST_STRING.writeTo(bos);
+    byte[] roundTripBytes = bos.toByteArray();
+    assertTrue(CLASSNAME + ".writeTo() must give back the same bytes",
+        Arrays.equals(BYTES, roundTripBytes));
+  }
+
+  public void testNewOutput() throws IOException {
+    ByteArrayOutputStream bos = new ByteArrayOutputStream();
+    ByteString.Output output = ByteString.newOutput();
+    TEST_STRING.writeTo(output);
+    assertEquals("Output Size returns correct result",
+        output.size(), TEST_STRING.size());
+    output.writeTo(bos);
+    assertTrue("Output.writeTo() must give back the same bytes",
+        Arrays.equals(BYTES, bos.toByteArray()));
+
+    // write the output stream to itself! This should cause it to double
+    output.writeTo(output);
+    assertEquals("Writing an output stream to itself is successful",
+        TEST_STRING.concat(TEST_STRING), output.toByteString());
+
+    output.reset();
+    assertEquals("Output.reset() resets the output", 0, output.size());
+    assertEquals("Output.reset() resets the output",
+        EMPTY, output.toByteString());
+  }
+
+  public void testToString() {
+    String testString = "I love unicode \u1234\u5678 characters";
+    ByteString unicode = forString(testString);
+    String roundTripString = unicode.toString(UTF_8);
+    assertEquals(CLASSNAME + " unicode must match", testString, roundTripString);
+  }
+
+  public void testCharsetToString() {
+    String testString = "I love unicode \u1234\u5678 characters";
+    ByteString unicode = forString(testString);
+    String roundTripString = unicode.toString(UTF_8);
+    assertEquals(CLASSNAME + " unicode must match", testString, roundTripString);
+  }
+
+  public void testToString_returnsCanonicalEmptyString() {
+    assertSame(CLASSNAME + " must be the same string references",
+        EMPTY.toString(UTF_8),
+        UnsafeByteStrings.unsafeWrap(ByteBuffer.wrap(new byte[0])).toString(UTF_8));
+  }
+
+  public void testToString_raisesException() {
+    try {
+      EMPTY.toString("invalid");
+      fail("Should have thrown an exception.");
+    } catch (UnsupportedEncodingException expected) {
+      // This is success
+    }
+
+    try {
+      TEST_STRING.toString("invalid");
+      fail("Should have thrown an exception.");
+    } catch (UnsupportedEncodingException expected) {
+      // This is success
+    }
+  }
+
+  public void testEquals() {
+    assertEquals(CLASSNAME + " must not equal null", false, TEST_STRING.equals(null));
+    assertEquals(CLASSNAME + " must equal self", TEST_STRING, TEST_STRING);
+    assertFalse(CLASSNAME + " must not equal the empty string",
+        TEST_STRING.equals(EMPTY));
+    assertEquals(CLASSNAME + " empty strings must be equal",
+        EMPTY, TEST_STRING.substring(55, 55));
+    assertEquals(CLASSNAME + " must equal another string with the same value",
+        TEST_STRING, UnsafeByteStrings.unsafeWrap(BUFFER));
+
+    byte[] mungedBytes = mungedBytes();
+    assertFalse(CLASSNAME + " must not equal every string with the same length",
+        TEST_STRING.equals(UnsafeByteStrings.unsafeWrap(ByteBuffer.wrap(mungedBytes))));
+  }
+
+  public void testEqualsLiteralByteString() {
+    ByteString literal = ByteString.copyFrom(BYTES);
+    assertEquals(CLASSNAME + " must equal LiteralByteString with same value", literal,
+        TEST_STRING);
+    assertEquals(CLASSNAME + " must equal LiteralByteString with same value", TEST_STRING,
+        literal);
+    assertFalse(CLASSNAME + " must not equal the empty string",
+        TEST_STRING.equals(ByteString.EMPTY));
+    assertEquals(CLASSNAME + " empty strings must be equal",
+        ByteString.EMPTY, TEST_STRING.substring(55, 55));
+
+    literal = ByteString.copyFrom(mungedBytes());
+    assertFalse(CLASSNAME + " must not equal every LiteralByteString with the same length",
+        TEST_STRING.equals(literal));
+    assertFalse(CLASSNAME + " must not equal every LiteralByteString with the same length",
+        literal.equals(TEST_STRING));
+  }
+
+  public void testEqualsRopeByteString() {
+    ByteString p1 = ByteString.copyFrom(BYTES, 0, 5);
+    ByteString p2 = ByteString.copyFrom(BYTES, 5, BYTES.length - 5);
+    ByteString rope = p1.concat(p2);
+
+    assertEquals(CLASSNAME + " must equal RopeByteString with same value", rope,
+        TEST_STRING);
+    assertEquals(CLASSNAME + " must equal RopeByteString with same value", TEST_STRING,
+        rope);
+    assertFalse(CLASSNAME + " must not equal the empty string",
+        TEST_STRING.equals(ByteString.EMPTY.concat(ByteString.EMPTY)));
+    assertEquals(CLASSNAME + " empty strings must be equal",
+        ByteString.EMPTY.concat(ByteString.EMPTY), TEST_STRING.substring(55, 55));
+
+    byte[] mungedBytes = mungedBytes();
+    p1 = ByteString.copyFrom(mungedBytes, 0, 5);
+    p2 = ByteString.copyFrom(mungedBytes, 5, mungedBytes.length - 5);
+    rope = p1.concat(p2);
+    assertFalse(CLASSNAME + " must not equal every RopeByteString with the same length",
+        TEST_STRING.equals(rope));
+    assertFalse(CLASSNAME + " must not equal every RopeByteString with the same length",
+        rope.equals(TEST_STRING));
+  }
+
+  private byte[] mungedBytes() {
+    byte[] mungedBytes = new byte[BYTES.length];
+    System.arraycopy(BYTES, 0, mungedBytes, 0, BYTES.length);
+    mungedBytes[mungedBytes.length - 5] = (byte) (mungedBytes[mungedBytes.length - 5] ^ 0xFF);
+    return mungedBytes;
+  }
+
+  public void testHashCode() {
+    int hash = TEST_STRING.hashCode();
+    assertEquals(CLASSNAME + " must have expected hashCode", EXPECTED_HASH, hash);
+  }
+
+  public void testPeekCachedHashCode() {
+    ByteString newString = UnsafeByteStrings.unsafeWrap(BUFFER);
+    assertEquals(CLASSNAME + ".peekCachedHashCode() should return zero at first", 0,
+        newString.peekCachedHashCode());
+    newString.hashCode();
+    assertEquals(CLASSNAME + ".peekCachedHashCode should return zero at first",
+        EXPECTED_HASH, newString.peekCachedHashCode());
+  }
+
+  public void testPartialHash() {
+    // partialHash() is more strenuously tested elsewhere by testing hashes of substrings.
+    // This test would fail if the expected hash were 1.  It's not.
+    int hash = TEST_STRING.partialHash(TEST_STRING.size(), 0, TEST_STRING.size());
+    assertEquals(CLASSNAME + ".partialHash() must yield expected hashCode",
+        EXPECTED_HASH, hash);
+  }
+
+  public void testNewInput() throws IOException {
+    InputStream input = TEST_STRING.newInput();
+    assertEquals("InputStream.available() returns correct value",
+        TEST_STRING.size(), input.available());
+    boolean stillEqual = true;
+    for (byte referenceByte : BYTES) {
+      int expectedInt = (referenceByte & 0xFF);
+      stillEqual = (expectedInt == input.read());
+    }
+    assertEquals("InputStream.available() returns correct value",
+        0, input.available());
+    assertTrue(CLASSNAME + " must give the same bytes from the InputStream", stillEqual);
+    assertEquals(CLASSNAME + " InputStream must now be exhausted", -1, input.read());
+  }
+
+  public void testNewInput_skip() throws IOException {
+    InputStream input = TEST_STRING.newInput();
+    int stringSize = TEST_STRING.size();
+    int nearEndIndex = stringSize * 2 / 3;
+    long skipped1 = input.skip(nearEndIndex);
+    assertEquals("InputStream.skip()", skipped1, nearEndIndex);
+    assertEquals("InputStream.available()",
+        stringSize - skipped1, input.available());
+    assertTrue("InputStream.mark() is available", input.markSupported());
+    input.mark(0);
+    assertEquals("InputStream.skip(), read()",
+        TEST_STRING.byteAt(nearEndIndex) & 0xFF, input.read());
+    assertEquals("InputStream.available()",
+        stringSize - skipped1 - 1, input.available());
+    long skipped2 = input.skip(stringSize);
+    assertEquals("InputStream.skip() incomplete",
+        skipped2, stringSize - skipped1 - 1);
+    assertEquals("InputStream.skip(), no more input", 0, input.available());
+    assertEquals("InputStream.skip(), no more input", -1, input.read());
+    input.reset();
+    assertEquals("InputStream.reset() succeded",
+        stringSize - skipped1, input.available());
+    assertEquals("InputStream.reset(), read()",
+        TEST_STRING.byteAt(nearEndIndex) & 0xFF, input.read());
+  }
+
+  public void testNewCodedInput() throws IOException {
+    CodedInputStream cis = TEST_STRING.newCodedInput();
+    byte[] roundTripBytes = cis.readRawBytes(BYTES.length);
+    assertTrue(CLASSNAME + " must give the same bytes back from the CodedInputStream",
+        Arrays.equals(BYTES, roundTripBytes));
+    assertTrue(CLASSNAME + " CodedInputStream must now be exhausted", cis.isAtEnd());
+  }
+
+  /**
+   * Make sure we keep things simple when concatenating with empty. See also
+   * {@link ByteStringTest#testConcat_empty()}.
+   */
+  public void testConcat_empty() {
+    assertSame(CLASSNAME + " concatenated with empty must give " + CLASSNAME,
+        TEST_STRING.concat(EMPTY), TEST_STRING);
+    assertSame("empty concatenated with " + CLASSNAME + " must give " + CLASSNAME,
+        EMPTY.concat(TEST_STRING), TEST_STRING);
+  }
+
+  public void testJavaSerialization() throws Exception {
+    ByteArrayOutputStream out = new ByteArrayOutputStream();
+    ObjectOutputStream oos = new ObjectOutputStream(out);
+    oos.writeObject(TEST_STRING);
+    oos.close();
+    byte[] pickled = out.toByteArray();
+    InputStream in = new ByteArrayInputStream(pickled);
+    ObjectInputStream ois = new ObjectInputStream(in);
+    Object o = ois.readObject();
+    assertTrue("Didn't get a ByteString back", o instanceof ByteString);
+    assertEquals("Should get an equal ByteString back", TEST_STRING, o);
+  }
+
+  private static ByteString forString(String str) {
+    return UnsafeByteStrings.unsafeWrap(ByteBuffer.wrap(str.getBytes(UTF_8)));
+  }
+}
diff --git a/java/src/test/java/com/google/protobuf/ProtobufArrayListTest.java b/java/src/test/java/com/google/protobuf/ProtobufArrayListTest.java
index f9f5e9c7..245c3dee 100644
--- a/java/src/test/java/com/google/protobuf/ProtobufArrayListTest.java
+++ b/java/src/test/java/com/google/protobuf/ProtobufArrayListTest.java
@@ -243,7 +243,7 @@ public class ProtobufArrayListTest extends TestCase {
     }
     
     try {
-      list.removeAll(Collections.<Double>emptyList());
+      list.removeAll(Collections.emptyList());
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
@@ -264,7 +264,7 @@ public class ProtobufArrayListTest extends TestCase {
     }
     
     try {
-      list.retainAll(Collections.<Double>emptyList());
+      list.retainAll(Collections.emptyList());
       fail();
     } catch (UnsupportedOperationException e) {
       // expected
diff --git a/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java b/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java
index cc385599..dc56f2e9 100644
--- a/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java
+++ b/java/src/test/java/com/google/protobuf/RopeByteStringSubstringTest.java
@@ -96,7 +96,7 @@ public class RopeByteStringSubstringTest extends LiteralByteStringTest {
   }
 
   @Override
-  public void testCharsetToString() throws UnsupportedEncodingException {
+  public void testCharsetToString() {
     String sourceString = "I love unicode \u1234\u5678 characters";
     ByteString sourceByteString = ByteString.copyFromUtf8(sourceString);
     int copies = 250;
diff --git a/java/src/test/java/com/google/protobuf/TestUtil.java b/java/src/test/java/com/google/protobuf/TestUtil.java
index 792e8665..01acb884 100644
--- a/java/src/test/java/com/google/protobuf/TestUtil.java
+++ b/java/src/test/java/com/google/protobuf/TestUtil.java
@@ -300,6 +300,16 @@ public final class TestUtil {
   }
 
   /**
+   * Get a {@code TestAllTypesLite.Builder} with all fields set as they would be by
+   * {@link #setAllFields(TestAllTypesLite.Builder)}.
+   */
+  public static TestAllTypesLite.Builder getAllLiteSetBuilder() {
+    TestAllTypesLite.Builder builder = TestAllTypesLite.newBuilder();
+    setAllFields(builder);
+    return builder;
+  }
+
+  /**
    * Get a {@code TestAllExtensions} with all fields set as they would be by
    * {@link #setAllExtensions(TestAllExtensions.Builder)}.
    */
@@ -339,6 +349,150 @@ public final class TestUtil {
     setPackedExtensions(builder);
     return builder.build();
   }
+  
+  /**
+   * Set every field of {@code builder} to the values expected by
+   * {@code assertAllFieldsSet()}.
+   */
+  public static void setAllFields(TestAllTypesLite.Builder builder) {
+    builder.setOptionalInt32   (101);
+    builder.setOptionalInt64   (102);
+    builder.setOptionalUint32  (103);
+    builder.setOptionalUint64  (104);
+    builder.setOptionalSint32  (105);
+    builder.setOptionalSint64  (106);
+    builder.setOptionalFixed32 (107);
+    builder.setOptionalFixed64 (108);
+    builder.setOptionalSfixed32(109);
+    builder.setOptionalSfixed64(110);
+    builder.setOptionalFloat   (111);
+    builder.setOptionalDouble  (112);
+    builder.setOptionalBool    (true);
+    builder.setOptionalString  ("115");
+    builder.setOptionalBytes   (toBytes("116"));
+
+    builder.setOptionalGroup(
+        TestAllTypesLite.OptionalGroup.newBuilder().setA(117).build());
+    builder.setOptionalNestedMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(118).build());
+    builder.setOptionalForeignMessage(
+        ForeignMessageLite.newBuilder().setC(119).build());
+    builder.setOptionalImportMessage(
+        ImportMessageLite.newBuilder().setD(120).build());
+    builder.setOptionalPublicImportMessage(
+        PublicImportMessageLite.newBuilder().setE(126).build());
+    builder.setOptionalLazyMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(127).build());
+
+    builder.setOptionalNestedEnum (TestAllTypesLite.NestedEnum.BAZ);
+    builder.setOptionalForeignEnum(ForeignEnumLite.FOREIGN_LITE_BAZ);
+    builder.setOptionalImportEnum (ImportEnumLite.IMPORT_LITE_BAZ);
+
+    builder.setOptionalStringPiece("124");
+    builder.setOptionalCord("125");
+
+    // -----------------------------------------------------------------
+
+    builder.addRepeatedInt32   (201);
+    builder.addRepeatedInt64   (202);
+    builder.addRepeatedUint32  (203);
+    builder.addRepeatedUint64  (204);
+    builder.addRepeatedSint32  (205);
+    builder.addRepeatedSint64  (206);
+    builder.addRepeatedFixed32 (207);
+    builder.addRepeatedFixed64 (208);
+    builder.addRepeatedSfixed32(209);
+    builder.addRepeatedSfixed64(210);
+    builder.addRepeatedFloat   (211);
+    builder.addRepeatedDouble  (212);
+    builder.addRepeatedBool    (true);
+    builder.addRepeatedString  ("215");
+    builder.addRepeatedBytes   (toBytes("216"));
+
+    builder.addRepeatedGroup(
+        TestAllTypesLite.RepeatedGroup.newBuilder().setA(217).build());
+    builder.addRepeatedNestedMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(218).build());
+    builder.addRepeatedForeignMessage(
+        ForeignMessageLite.newBuilder().setC(219).build());
+    builder.addRepeatedImportMessage(
+        ImportMessageLite.newBuilder().setD(220).build());
+    builder.addRepeatedLazyMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(227).build());
+
+    builder.addRepeatedNestedEnum (TestAllTypesLite.NestedEnum.BAR);
+    builder.addRepeatedForeignEnum(ForeignEnumLite.FOREIGN_LITE_BAR);
+    builder.addRepeatedImportEnum (ImportEnumLite.IMPORT_LITE_BAR);
+
+    builder.addRepeatedStringPiece("224");
+    builder.addRepeatedCord("225");
+
+    // Add a second one of each field.
+    builder.addRepeatedInt32   (301);
+    builder.addRepeatedInt64   (302);
+    builder.addRepeatedUint32  (303);
+    builder.addRepeatedUint64  (304);
+    builder.addRepeatedSint32  (305);
+    builder.addRepeatedSint64  (306);
+    builder.addRepeatedFixed32 (307);
+    builder.addRepeatedFixed64 (308);
+    builder.addRepeatedSfixed32(309);
+    builder.addRepeatedSfixed64(310);
+    builder.addRepeatedFloat   (311);
+    builder.addRepeatedDouble  (312);
+    builder.addRepeatedBool    (false);
+    builder.addRepeatedString  ("315");
+    builder.addRepeatedBytes   (toBytes("316"));
+
+    builder.addRepeatedGroup(
+        TestAllTypesLite.RepeatedGroup.newBuilder().setA(317).build());
+    builder.addRepeatedNestedMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(318).build());
+    builder.addRepeatedForeignMessage(
+        ForeignMessageLite.newBuilder().setC(319).build());
+    builder.addRepeatedImportMessage(
+        ImportMessageLite.newBuilder().setD(320).build());
+    builder.addRepeatedLazyMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(327).build());
+
+    builder.addRepeatedNestedEnum (TestAllTypesLite.NestedEnum.BAZ);
+    builder.addRepeatedForeignEnum(ForeignEnumLite.FOREIGN_LITE_BAZ);
+    builder.addRepeatedImportEnum (ImportEnumLite.IMPORT_LITE_BAZ);
+
+    builder.addRepeatedStringPiece("324");
+    builder.addRepeatedCord("325");
+
+    // -----------------------------------------------------------------
+
+    builder.setDefaultInt32   (401);
+    builder.setDefaultInt64   (402);
+    builder.setDefaultUint32  (403);
+    builder.setDefaultUint64  (404);
+    builder.setDefaultSint32  (405);
+    builder.setDefaultSint64  (406);
+    builder.setDefaultFixed32 (407);
+    builder.setDefaultFixed64 (408);
+    builder.setDefaultSfixed32(409);
+    builder.setDefaultSfixed64(410);
+    builder.setDefaultFloat   (411);
+    builder.setDefaultDouble  (412);
+    builder.setDefaultBool    (false);
+    builder.setDefaultString  ("415");
+    builder.setDefaultBytes   (toBytes("416"));
+
+    builder.setDefaultNestedEnum (TestAllTypesLite.NestedEnum.FOO);
+    builder.setDefaultForeignEnum(ForeignEnumLite.FOREIGN_LITE_FOO);
+    builder.setDefaultImportEnum (ImportEnumLite.IMPORT_LITE_FOO);
+
+    builder.setDefaultStringPiece("424");
+    builder.setDefaultCord("425");
+
+    builder.setOneofUint32(601);
+    builder.setOneofNestedMessage(
+        TestAllTypesLite.NestedMessage.newBuilder().setBb(602).build());
+    builder.setOneofString("603");
+    builder.setOneofBytes(toBytes("604"));
+  }
 
   /**
    * Set every field of {@code message} to the values expected by
diff --git a/java/src/test/java/com/google/protobuf/map_test.proto b/java/src/test/java/com/google/protobuf/map_test.proto
index 2f7709be..2280ac03 100644
--- a/java/src/test/java/com/google/protobuf/map_test.proto
+++ b/java/src/test/java/com/google/protobuf/map_test.proto
@@ -36,7 +36,6 @@ option java_package = "map_test";
 option java_outer_classname = "MapTestProto";
 option java_generate_equals_and_hash = true;
 
-
 message TestMap {
   message MessageValue {
     int32 value = 1;
diff --git a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
index 8c37c03c..2b1f65e4 100644
--- a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
+++ b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
@@ -45,7 +45,6 @@ option java_package = "com.google.protobuf";
 option java_outer_classname = "TestBadIdentifiersProto";
 option java_generate_equals_and_hash = true;
 
-
 message TestMessage {
   optional string cached_size = 1;
   optional string serialized_size = 2;
diff --git a/java/util/src/main/java/com/google/protobuf/util/FieldMaskUtil.java b/java/util/src/main/java/com/google/protobuf/util/FieldMaskUtil.java
index 7bf87858..535be0fa 100644
--- a/java/util/src/main/java/com/google/protobuf/util/FieldMaskUtil.java
+++ b/java/util/src/main/java/com/google/protobuf/util/FieldMaskUtil.java
@@ -30,6 +30,9 @@
 
 package com.google.protobuf.util;
 
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.primitives.Ints;
 import com.google.protobuf.Descriptors.Descriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
 import com.google.protobuf.FieldMask;
@@ -37,7 +40,6 @@ import com.google.protobuf.Internal;
 import com.google.protobuf.Message;
 
 import java.util.Arrays;
-import java.util.List;
 
 /**
  * Utility helper functions to work with {@link com.google.protobuf.FieldMask}.
@@ -53,6 +55,7 @@ public class FieldMaskUtil {
    * Converts a FieldMask to a string.
    */
   public static String toString(FieldMask fieldMask) {
+    // TODO(xiaofeng): Consider using com.google.common.base.Joiner here instead.
     StringBuilder result = new StringBuilder();
     boolean first = true;
     for (String value : fieldMask.getPathsList()) {
@@ -74,6 +77,7 @@ public class FieldMaskUtil {
    * Parses from a string to a FieldMask.
    */
   public static FieldMask fromString(String value) {
+    // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
     return fromStringList(
         null, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
   }
@@ -83,8 +87,8 @@ public class FieldMaskUtil {
    * 
    * @throws IllegalArgumentException if any of the field path is invalid.
    */
-  public static FieldMask fromString(Class<? extends Message> type, String value)
-      throws IllegalArgumentException {
+  public static FieldMask fromString(Class<? extends Message> type, String value) {
+    // TODO(xiaofeng): Consider using com.google.common.base.Splitter here instead.
     return fromStringList(
         type, Arrays.asList(value.split(FIELD_PATH_SEPARATOR_REGEX)));
   }
@@ -94,9 +98,9 @@ public class FieldMaskUtil {
    *
    * @throws IllegalArgumentException if any of the field path is not valid.
    */
+  // TODO(xiaofeng): Consider renaming fromStrings()
   public static FieldMask fromStringList(
-      Class<? extends Message> type, List<String> paths)
-      throws IllegalArgumentException {
+      Class<? extends Message> type, Iterable<String> paths) {
     FieldMask.Builder builder = FieldMask.newBuilder();
     for (String path : paths) {
       if (path.isEmpty()) {
@@ -113,15 +117,74 @@ public class FieldMaskUtil {
   }
 
   /**
+   * Constructs a FieldMask from the passed field numbers.
+   *
+   * @throws IllegalArugmentException if any of the fields are invalid for the message.
+   */
+  public static FieldMask fromFieldNumbers(Class<? extends Message> type, int... fieldNumbers) {
+    return fromFieldNumbers(type, Ints.asList(fieldNumbers));
+  }
+
+  /**
+   * Constructs a FieldMask from the passed field numbers.
+   *
+   * @throws IllegalArugmentException if any of the fields are invalid for the message.
+   */
+  public static FieldMask fromFieldNumbers(
+      Class<? extends Message> type, Iterable<Integer> fieldNumbers) {
+    Descriptor descriptor = Internal.getDefaultInstance(type).getDescriptorForType();
+
+    FieldMask.Builder builder = FieldMask.newBuilder();
+    for (Integer fieldNumber : fieldNumbers) {
+      FieldDescriptor field = descriptor.findFieldByNumber(fieldNumber);
+      checkArgument(
+          field != null,
+          String.format("%s is not a valid field number for %s.", fieldNumber, type));
+      builder.addPaths(field.getName());
+    }
+    return builder.build();
+  }
+
+  /**
+   * Checks whether paths in a given fields mask are valid.
+   */
+  public static boolean isValid(Class<? extends Message> type, FieldMask fieldMask) {
+    Descriptor descriptor =
+        Internal.getDefaultInstance(type).getDescriptorForType();
+    
+    return isValid(descriptor, fieldMask);
+  }
+  
+  /**
+   * Checks whether paths in a given fields mask are valid.
+   */
+  public static boolean isValid(Descriptor descriptor, FieldMask fieldMask) {
+    for (String path : fieldMask.getPathsList()) {
+      if (!isValid(descriptor, path)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
    * Checks whether a given field path is valid.
    */
   public static boolean isValid(Class<? extends Message> type, String path) {
+    Descriptor descriptor =
+        Internal.getDefaultInstance(type).getDescriptorForType();
+    
+    return isValid(descriptor, path);
+  }
+
+  /**
+   * Checks whether paths in a given fields mask are valid.
+   */
+  public static boolean isValid(Descriptor descriptor, String path) {
     String[] parts = path.split(FIELD_SEPARATOR_REGEX);
     if (parts.length == 0) {
       return false;
     }
-    Descriptor descriptor =
-        Internal.getDefaultInstance(type).getDescriptorForType();
     for (String name : parts) {
       if (descriptor == null) {
         return false;
@@ -171,7 +234,7 @@ public class FieldMaskUtil {
   /**
    * Options to customize merging behavior.
    */
-  public static class MergeOptions {
+  public static final class MergeOptions {
     private boolean replaceMessageFields = false;
     private boolean replaceRepeatedFields = false;
 
diff --git a/java/util/src/main/java/com/google/protobuf/util/JsonFormat.java b/java/util/src/main/java/com/google/protobuf/util/JsonFormat.java
index c9a39153..d13ff0ed 100644
--- a/java/util/src/main/java/com/google/protobuf/util/JsonFormat.java
+++ b/java/util/src/main/java/com/google/protobuf/util/JsonFormat.java
@@ -78,6 +78,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.TreeMap;
 import java.util.logging.Logger;
 
 /**
@@ -99,7 +100,7 @@ public class JsonFormat {
    * Creates a {@link Printer} with default configurations.
    */
   public static Printer printer() {
-    return new Printer(TypeRegistry.getEmptyTypeRegistry());
+    return new Printer(TypeRegistry.getEmptyTypeRegistry(), false, false);
   }
   
   /**
@@ -107,9 +108,16 @@ public class JsonFormat {
    */
   public static class Printer {
     private final TypeRegistry registry;
-    
-    private Printer(TypeRegistry registry) {
+    private final boolean includingDefaultValueFields;
+    private final boolean preservingProtoFieldNames;
+
+    private Printer(
+        TypeRegistry registry,
+        boolean includingDefaultValueFields,
+        boolean preservingProtoFieldNames) {
       this.registry = registry;
+      this.includingDefaultValueFields = includingDefaultValueFields;
+      this.preservingProtoFieldNames = preservingProtoFieldNames;
     }
     
     /**
@@ -122,7 +130,27 @@ public class JsonFormat {
       if (this.registry != TypeRegistry.getEmptyTypeRegistry()) {
         throw new IllegalArgumentException("Only one registry is allowed.");
       }
-      return new Printer(registry);
+      return new Printer(registry, includingDefaultValueFields, preservingProtoFieldNames);
+    }
+
+    /**
+     * Creates a new {@link Printer} that will also print fields set to their
+     * defaults. Empty repeated fields and map fields will be printed as well.
+     * The new Printer clones all other configurations from the current
+     * {@link Printer}.
+     */
+    public Printer includingDefaultValueFields() {
+      return new Printer(registry, true, preservingProtoFieldNames);
+    }
+
+    /**
+     * Creates a new {@link Printer} that is configured to use the original proto
+     * field names as defined in the .proto file rather than converting them to
+     * lowerCamelCase. The new Printer clones all other configurations from the
+     * current {@link Printer}.
+     */
+    public Printer preservingProtoFieldNames() {
+      return new Printer(registry, includingDefaultValueFields, true);
     }
     
     /**
@@ -136,7 +164,8 @@ public class JsonFormat {
         throws IOException {
       // TODO(xiaofeng): Investigate the allocation overhead and optimize for
       // mobile.
-      new PrinterImpl(registry, output).print(message);
+      new PrinterImpl(registry, includingDefaultValueFields, preservingProtoFieldNames, output)
+          .print(message);
     }
 
     /**
@@ -298,7 +327,7 @@ public class JsonFormat {
 
       private void addFile(FileDescriptor file) {
         // Skip the file if it's already added.
-        if (files.contains(file.getName())) {
+        if (!files.add(file.getFullName())) {
           return;
         }
         for (FileDescriptor dependency : file.getDependencies()) {
@@ -397,6 +426,8 @@ public class JsonFormat {
    */
   private static final class PrinterImpl {
     private final TypeRegistry registry;
+    private final boolean includingDefaultValueFields;
+    private final boolean preservingProtoFieldNames;
     private final TextGenerator generator;
     // We use Gson to help handle string escapes.
     private final Gson gson;
@@ -405,8 +436,14 @@ public class JsonFormat {
       private static final Gson DEFAULT_GSON = new Gson();
     }
 
-    PrinterImpl(TypeRegistry registry, Appendable jsonOutput) {
+    PrinterImpl(
+        TypeRegistry registry,
+        boolean includingDefaultValueFields,
+        boolean preservingProtoFieldNames,
+        Appendable jsonOutput) {
       this.registry = registry;
+      this.includingDefaultValueFields = includingDefaultValueFields;
+      this.preservingProtoFieldNames = preservingProtoFieldNames;
       this.generator = new TextGenerator(jsonOutput);
       this.gson = GsonHolder.DEFAULT_GSON;
     }
@@ -647,13 +684,23 @@ public class JsonFormat {
         generator.print("\"@type\": " + gson.toJson(typeUrl));
         printedField = true;
       }
-      for (Map.Entry<FieldDescriptor, Object> field
-          : message.getAllFields().entrySet()) {
-        // Skip unknown enum fields.
-        if (field.getValue() instanceof EnumValueDescriptor
-            && ((EnumValueDescriptor) field.getValue()).getIndex() == -1) {
-          continue;
+      Map<FieldDescriptor, Object> fieldsToPrint = null;
+      if (includingDefaultValueFields) {
+        fieldsToPrint = new TreeMap<FieldDescriptor, Object>();
+        for (FieldDescriptor field : message.getDescriptorForType().getFields()) {
+          if (field.isOptional()
+              && field.getJavaType() == FieldDescriptor.JavaType.MESSAGE
+              && !message.hasField(field)) {
+            // Always skip empty optional message fields. If not we will recurse indefinitely if
+            // a message has itself as a sub-field.
+            continue;
+          }
+          fieldsToPrint.put(field, message.getField(field));
         }
+      } else {
+        fieldsToPrint = message.getAllFields();
+      }
+      for (Map.Entry<FieldDescriptor, Object> field : fieldsToPrint.entrySet()) {
         if (printedField) {
           // Add line-endings for the previous field.
           generator.print(",\n");
@@ -673,7 +720,11 @@ public class JsonFormat {
 
     private void printField(FieldDescriptor field, Object value)
         throws IOException {
-      generator.print("\"" + fieldNameToCamelName(field.getName()) + "\": ");
+      if (preservingProtoFieldNames) {
+        generator.print("\"" + field.getName() + "\": ");
+      } else {
+        generator.print("\"" + field.getJsonName() + "\": ");
+      }
       if (field.isMapField()) {
         printMapFieldValue(field, value);
       } else if (field.isRepeated()) {
@@ -689,11 +740,6 @@ public class JsonFormat {
       generator.print("[");
       boolean printedElement = false;
       for (Object element : (List) value) {
-        // Skip unknown enum entries.
-        if (element instanceof EnumValueDescriptor
-            && ((EnumValueDescriptor) element).getIndex() == -1) {
-          continue;
-        }
         if (printedElement) {
           generator.print(", ");
         } else {
@@ -720,11 +766,6 @@ public class JsonFormat {
         Message entry = (Message) element;
         Object entryKey = entry.getField(keyField);
         Object entryValue = entry.getField(valueField);
-        // Skip unknown enum entries.
-        if (entryValue instanceof EnumValueDescriptor
-            && ((EnumValueDescriptor) entryValue).getIndex() == -1) {
-          continue;
-        }
         if (printedElement) {
           generator.print(",\n");
         } else {
@@ -871,8 +912,13 @@ public class JsonFormat {
               generator.print("\"");
             }
           } else {
-            generator.print(
-                "\"" + ((EnumValueDescriptor) value).getName() + "\"");
+            if (((EnumValueDescriptor) value).getIndex() == -1) {
+              generator.print(
+                  String.valueOf(((EnumValueDescriptor) value).getNumber()));
+            } else {
+              generator.print(
+                  "\"" + ((EnumValueDescriptor) value).getName() + "\"");
+            }
           }
           break;
 
@@ -916,38 +962,6 @@ public class JsonFormat {
     }
     return parts[1];
   }
-
-  private static String fieldNameToCamelName(String name) {
-    StringBuilder result = new StringBuilder(name.length());
-    boolean isNextUpperCase = false;
-    for (int i = 0; i < name.length(); i++) {
-      Character ch = name.charAt(i);
-      if (Character.isLowerCase(ch)) {
-        if (isNextUpperCase) {
-          result.append(Character.toUpperCase(ch));
-        } else {
-          result.append(ch);
-        }
-        isNextUpperCase = false;
-      } else if (Character.isUpperCase(ch)) {
-        if (i == 0 && !isNextUpperCase) {
-          // Force first letter to lower-case unless explicitly told to
-          // capitalize it.
-          result.append(Character.toLowerCase(ch));
-        } else {
-          // Capital letters after the first are left as-is.
-          result.append(ch);
-        }
-        isNextUpperCase = false;
-      } else if (Character.isDigit(ch)) {
-        result.append(ch);
-        isNextUpperCase = true;
-      } else {
-        isNextUpperCase = true;
-      }
-    }
-    return result.toString();
-  }
   
   private static class ParserImpl {
     private final TypeRegistry registry;
@@ -1085,7 +1099,8 @@ public class JsonFormat {
         Map<String, FieldDescriptor> fieldNameMap =
             new HashMap<String, FieldDescriptor>();
         for (FieldDescriptor field : descriptor.getFields()) {
-          fieldNameMap.put(fieldNameToCamelName(field.getName()), field);
+          fieldNameMap.put(field.getName(), field);
+          fieldNameMap.put(field.getJsonName(), field);
         }
         fieldNameMaps.put(descriptor, fieldNameMap);
         return fieldNameMap;
@@ -1244,7 +1259,25 @@ public class JsonFormat {
     
     private void mergeField(FieldDescriptor field, JsonElement json,
         Message.Builder builder) throws InvalidProtocolBufferException {
-      if (json instanceof JsonNull) {
+      if (field.isRepeated()) {
+        if (builder.getRepeatedFieldCount(field) > 0) {
+          throw new InvalidProtocolBufferException(
+              "Field " + field.getFullName() + " has already been set.");
+        }
+      } else {
+        if (builder.hasField(field)) {
+          throw new InvalidProtocolBufferException(
+              "Field " + field.getFullName() + " has already been set.");
+        }
+        if (field.getContainingOneof() != null
+            && builder.getOneofFieldDescriptor(field.getContainingOneof()) != null) {
+          FieldDescriptor other = builder.getOneofFieldDescriptor(field.getContainingOneof());
+          throw new InvalidProtocolBufferException(
+              "Cannot set field " + field.getFullName() + " because another field "
+              + other.getFullName() + " belonging to the same oneof has already been set ");
+        }
+      }
+      if (field.isRepeated() && json instanceof JsonNull) {
         // We allow "null" as value for all field types and treat it as if the
         // field is not present.
         return;
@@ -1282,7 +1315,8 @@ public class JsonFormat {
         Object value = parseFieldValue(
             valueField, entry.getValue(), entryBuilder);
         if (value == null) {
-          value = getDefaultValue(valueField, entryBuilder);
+          throw new InvalidProtocolBufferException(
+              "Map value cannot be null.");
         }
         entryBuilder.setField(keyField, key);
         entryBuilder.setField(valueField, value);
@@ -1341,7 +1375,8 @@ public class JsonFormat {
       for (int i = 0; i < array.size(); ++i) {
         Object value = parseFieldValue(field, array.get(i), builder);
         if (value == null) {
-          value = getDefaultValue(field, builder);
+          throw new InvalidProtocolBufferException(
+              "Repeated field elements cannot be null");
         }
         builder.addRepeatedField(field, value);
       }
@@ -1352,6 +1387,15 @@ public class JsonFormat {
       try {
         return Integer.parseInt(json.getAsString());
       } catch (Exception e) {
+        // Fall through.
+      }
+      // JSON doesn't distinguish between integer values and floating point values so "1" and
+      // "1.000" are treated as equal in JSON. For this reason we accept floating point values for
+      // integer fields as well as long as it actually is an integer (i.e., round(value) == value).
+      try {
+        BigDecimal value = new BigDecimal(json.getAsString());
+        return value.intValueExact();
+      } catch (Exception e) {
         throw new InvalidProtocolBufferException("Not an int32 value: " + json);
       }
     }
@@ -1361,7 +1405,16 @@ public class JsonFormat {
       try {
         return Long.parseLong(json.getAsString());
       } catch (Exception e) {
-        throw new InvalidProtocolBufferException("Not an int64 value: " + json);
+        // Fall through.
+      }
+      // JSON doesn't distinguish between integer values and floating point values so "1" and
+      // "1.000" are treated as equal in JSON. For this reason we accept floating point values for
+      // integer fields as well as long as it actually is an integer (i.e., round(value) == value).
+      try {
+        BigDecimal value = new BigDecimal(json.getAsString());
+        return value.longValueExact();
+      } catch (Exception e) {
+        throw new InvalidProtocolBufferException("Not an int32 value: " + json);
       }
     }
     
@@ -1377,6 +1430,21 @@ public class JsonFormat {
       } catch (InvalidProtocolBufferException e) {
         throw e;
       } catch (Exception e) {
+        // Fall through.
+      }
+      // JSON doesn't distinguish between integer values and floating point values so "1" and
+      // "1.000" are treated as equal in JSON. For this reason we accept floating point values for
+      // integer fields as well as long as it actually is an integer (i.e., round(value) == value).
+      try {
+        BigDecimal decimalValue = new BigDecimal(json.getAsString());
+        BigInteger value = decimalValue.toBigIntegerExact();
+        if (value.signum() < 0 || value.compareTo(new BigInteger("FFFFFFFF", 16)) > 0) {
+          throw new InvalidProtocolBufferException("Out of range uint32 value: " + json);
+        }
+        return value.intValue();
+      } catch (InvalidProtocolBufferException e) {
+        throw e;
+      } catch (Exception e) {
         throw new InvalidProtocolBufferException(
             "Not an uint32 value: " + json);
       }
@@ -1388,7 +1456,8 @@ public class JsonFormat {
     private long parseUint64(JsonElement json)
         throws InvalidProtocolBufferException {
       try {
-        BigInteger value = new BigInteger(json.getAsString());
+        BigDecimal decimalValue = new BigDecimal(json.getAsString());
+        BigInteger value = decimalValue.toBigIntegerExact();
         if (value.compareTo(BigInteger.ZERO) < 0
             || value.compareTo(MAX_UINT64) > 0) {
           throw new InvalidProtocolBufferException(
@@ -1488,7 +1557,12 @@ public class JsonFormat {
       return json.getAsString();
     }
     
-    private ByteString parseBytes(JsonElement json) {
+    private ByteString parseBytes(JsonElement json) throws InvalidProtocolBufferException {
+      String encoded = json.getAsString();
+      if (encoded.length() % 4 != 0) {
+        throw new InvalidProtocolBufferException(
+            "Bytes field is not encoded in standard BASE64 with paddings: " + encoded);
+      }
       return ByteString.copyFrom(
           BaseEncoding.base64().decode(json.getAsString()));
     }
@@ -1498,9 +1572,25 @@ public class JsonFormat {
       String value = json.getAsString();
       EnumValueDescriptor result = enumDescriptor.findValueByName(value);
       if (result == null) {
-        throw new InvalidProtocolBufferException(
-            "Invalid enum value: " + value + " for enum type: "
-            + enumDescriptor.getFullName());
+        // Try to interpret the value as a number.
+        try {
+          int numericValue = parseInt32(json);
+          if (enumDescriptor.getFile().getSyntax() == FileDescriptor.Syntax.PROTO3) {
+            result = enumDescriptor.findValueByNumberCreatingIfUnknown(numericValue);
+          } else {
+            result = enumDescriptor.findValueByNumber(numericValue);
+          }
+        } catch (InvalidProtocolBufferException e) {
+          // Fall through. This exception is about invalid int32 value we get from parseInt32() but
+          // that's not the exception we want the user to see. Since result == null, we will throw
+          // an exception later.
+        }
+        
+        if (result == null) {
+          throw new InvalidProtocolBufferException(
+              "Invalid enum value: " + value + " for enum type: "
+              + enumDescriptor.getFullName());
+        }
       }
       return result;
     }
diff --git a/java/util/src/main/java/com/google/protobuf/util/TimeUtil.java b/java/util/src/main/java/com/google/protobuf/util/TimeUtil.java
index 6e4b7c03..3033182a 100644
--- a/java/util/src/main/java/com/google/protobuf/util/TimeUtil.java
+++ b/java/util/src/main/java/com/google/protobuf/util/TimeUtil.java
@@ -58,8 +58,12 @@ public class TimeUtil {
   private static final long MILLIS_PER_SECOND = 1000;
   private static final long MICROS_PER_SECOND = 1000000;
 
-  private static final SimpleDateFormat timestampFormat =
-    createTimestampFormat();
+  private static final ThreadLocal<SimpleDateFormat> timestampFormat =
+      new ThreadLocal<SimpleDateFormat>() {
+        protected SimpleDateFormat initialValue() {
+          return createTimestampFormat();
+        }
+      };
 
   private static SimpleDateFormat createTimestampFormat() {
     SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
@@ -96,7 +100,7 @@ public class TimeUtil {
       throw new IllegalArgumentException("Timestamp is out of range.");
     }
     Date date = new Date(timestamp.getSeconds() * MILLIS_PER_SECOND);
-    result.append(timestampFormat.format(date));
+    result.append(timestampFormat.get().format(date));
     // Format the nanos part.
     if (timestamp.getNanos() < 0 || timestamp.getNanos() >= NANOS_PER_SECOND) {
       throw new IllegalArgumentException("Timestamp has invalid nanos value.");
@@ -147,7 +151,7 @@ public class TimeUtil {
       secondValue = timeValue.substring(0, pointPosition);
       nanoValue = timeValue.substring(pointPosition + 1);
     }
-    Date date = timestampFormat.parse(secondValue);
+    Date date = timestampFormat.get().parse(secondValue);
     long seconds = date.getTime() / MILLIS_PER_SECOND;
     int nanos = nanoValue.isEmpty() ? 0 : parseNanos(nanoValue);
     // Parse timezone offsets.
diff --git a/java/util/src/test/java/com/google/protobuf/util/FieldMaskUtilTest.java b/java/util/src/test/java/com/google/protobuf/util/FieldMaskUtilTest.java
index 67fbe0b1..a312fc33 100644
--- a/java/util/src/test/java/com/google/protobuf/util/FieldMaskUtilTest.java
+++ b/java/util/src/test/java/com/google/protobuf/util/FieldMaskUtilTest.java
@@ -53,6 +53,21 @@ public class FieldMaskUtilTest extends TestCase {
         NestedTestAllTypes.class, "payload.nonexist"));
     
     assertTrue(FieldMaskUtil.isValid(
+        NestedTestAllTypes.class, FieldMaskUtil.fromString("payload")));
+    assertFalse(FieldMaskUtil.isValid(
+        NestedTestAllTypes.class, FieldMaskUtil.fromString("nonexist")));
+    assertFalse(FieldMaskUtil.isValid(
+        NestedTestAllTypes.class, FieldMaskUtil.fromString("payload,nonexist")));
+    
+    assertTrue(FieldMaskUtil.isValid(NestedTestAllTypes.getDescriptor(), "payload"));
+    assertFalse(FieldMaskUtil.isValid(NestedTestAllTypes.getDescriptor(), "nonexist"));
+    
+    assertTrue(FieldMaskUtil.isValid(
+        NestedTestAllTypes.getDescriptor(), FieldMaskUtil.fromString("payload")));
+    assertFalse(FieldMaskUtil.isValid(
+        NestedTestAllTypes.getDescriptor(), FieldMaskUtil.fromString("nonexist")));
+    
+    assertTrue(FieldMaskUtil.isValid(
         NestedTestAllTypes.class, "payload.optional_nested_message.bb"));
     // Repeated fields cannot have sub-paths.
     assertFalse(FieldMaskUtil.isValid(
@@ -74,7 +89,7 @@ public class FieldMaskUtilTest extends TestCase {
       addPaths("bar").addPaths("").build();
     assertEquals("foo,bar", FieldMaskUtil.toString(mask));
   }
-  
+
   public void testFromString() throws Exception {
     FieldMask mask = FieldMaskUtil.fromString("");
     assertEquals(0, mask.getPathsCount());
@@ -85,16 +100,16 @@ public class FieldMaskUtilTest extends TestCase {
     assertEquals(2, mask.getPathsCount());
     assertEquals("foo", mask.getPaths(0));
     assertEquals("bar.baz", mask.getPaths(1));
-    
+
     // Empty field paths are ignore.
     mask = FieldMaskUtil.fromString(",foo,,bar,");
     assertEquals(2, mask.getPathsCount());
     assertEquals("foo", mask.getPaths(0));
     assertEquals("bar", mask.getPaths(1));
-    
+
     // Check whether the field paths are valid if a class parameter is provided.
     mask = FieldMaskUtil.fromString(NestedTestAllTypes.class, ",payload");
-    
+
     try {
       mask = FieldMaskUtil.fromString(
           NestedTestAllTypes.class, "payload,nonexist");
@@ -103,6 +118,31 @@ public class FieldMaskUtilTest extends TestCase {
       // Expected.
     }
   }
+
+  public void testFromFieldNumbers() throws Exception {
+    FieldMask mask = FieldMaskUtil.fromFieldNumbers(TestAllTypes.class);
+    assertEquals(0, mask.getPathsCount());
+    mask =
+        FieldMaskUtil.fromFieldNumbers(
+            TestAllTypes.class, TestAllTypes.OPTIONAL_INT32_FIELD_NUMBER);
+    assertEquals(1, mask.getPathsCount());
+    assertEquals("optional_int32", mask.getPaths(0));
+    mask =
+        FieldMaskUtil.fromFieldNumbers(
+            TestAllTypes.class,
+            TestAllTypes.OPTIONAL_INT32_FIELD_NUMBER,
+            TestAllTypes.OPTIONAL_INT64_FIELD_NUMBER);
+    assertEquals(2, mask.getPathsCount());
+    assertEquals("optional_int32", mask.getPaths(0));
+    assertEquals("optional_int64", mask.getPaths(1));
+
+    try {
+      int invalidFieldNumber = 1000;
+      mask = FieldMaskUtil.fromFieldNumbers(TestAllTypes.class, invalidFieldNumber);
+      fail("Exception is expected.");
+    } catch (IllegalArgumentException expected) {
+    }
+  }
   
   public void testUnion() throws Exception {
     // Only test a simple case here and expect
diff --git a/java/util/src/test/java/com/google/protobuf/util/JsonFormatTest.java b/java/util/src/test/java/com/google/protobuf/util/JsonFormatTest.java
index ddf5ad2a..c0eb0330 100644
--- a/java/util/src/test/java/com/google/protobuf/util/JsonFormatTest.java
+++ b/java/util/src/test/java/com/google/protobuf/util/JsonFormatTest.java
@@ -51,9 +51,11 @@ import com.google.protobuf.util.JsonTestProto.TestAllTypes;
 import com.google.protobuf.util.JsonTestProto.TestAllTypes.NestedEnum;
 import com.google.protobuf.util.JsonTestProto.TestAllTypes.NestedMessage;
 import com.google.protobuf.util.JsonTestProto.TestAny;
+import com.google.protobuf.util.JsonTestProto.TestCustomJsonName;
 import com.google.protobuf.util.JsonTestProto.TestDuration;
 import com.google.protobuf.util.JsonTestProto.TestFieldMask;
 import com.google.protobuf.util.JsonTestProto.TestMap;
+import com.google.protobuf.util.JsonTestProto.TestOneof;
 import com.google.protobuf.util.JsonTestProto.TestStruct;
 import com.google.protobuf.util.JsonTestProto.TestTimestamp;
 import com.google.protobuf.util.JsonTestProto.TestWrappers;
@@ -196,9 +198,6 @@ public class JsonFormatTest extends TestCase {
   }
   
   public void testUnknownEnumValues() throws Exception {
-    // Unknown enum values will be dropped.
-    // TODO(xiaofeng): We may want to revisit this (whether we should omit
-    // unknown enum values).
     TestAllTypes message = TestAllTypes.newBuilder()
         .setOptionalNestedEnumValue(12345)
         .addRepeatedNestedEnumValue(12345)
@@ -206,8 +205,10 @@ public class JsonFormatTest extends TestCase {
         .build();
     assertEquals(
         "{\n"
-        + "  \"repeatedNestedEnum\": [\"FOO\"]\n"
+        + "  \"optionalNestedEnum\": 12345,\n"
+        + "  \"repeatedNestedEnum\": [12345, \"FOO\"]\n"
         + "}", toJsonString(message));
+    assertRoundTripEquals(message);
     
     TestMap.Builder mapBuilder = TestMap.newBuilder();
     mapBuilder.getMutableInt32ToEnumMapValue().put(1, 0);
@@ -216,9 +217,11 @@ public class JsonFormatTest extends TestCase {
     assertEquals(
         "{\n" 
         + "  \"int32ToEnumMap\": {\n" 
-        + "    \"1\": \"FOO\"\n" 
+        + "    \"1\": \"FOO\",\n"
+        + "    \"2\": 12345\n"
         + "  }\n" 
         + "}", toJsonString(mapMessage));
+    assertRoundTripEquals(mapMessage);
   }
   
   public void testSpecialFloatValues() throws Exception {
@@ -263,6 +266,35 @@ public class JsonFormatTest extends TestCase {
     assertEquals(true, message.getOptionalBool());
   }
   
+  public void testParserAcceptFloatingPointValueForIntegerField() throws Exception {
+    // Test that numeric values like "1.000", "1e5" will also be accepted.
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    mergeFromJson(
+        "{\n"
+            + "  \"repeatedInt32\": [1.000, 1e5, \"1.000\", \"1e5\"],\n"
+            + "  \"repeatedUint32\": [1.000, 1e5, \"1.000\", \"1e5\"],\n"
+            + "  \"repeatedInt64\": [1.000, 1e5, \"1.000\", \"1e5\"],\n"
+            + "  \"repeatedUint64\": [1.000, 1e5, \"1.000\", \"1e5\"]\n"
+            + "}", builder);
+    int[] expectedValues = new int[]{1, 100000, 1, 100000};
+    assertEquals(4, builder.getRepeatedInt32Count());
+    assertEquals(4, builder.getRepeatedUint32Count());
+    assertEquals(4, builder.getRepeatedInt64Count());
+    assertEquals(4, builder.getRepeatedUint64Count());
+    for (int i = 0; i < 4; ++i) {
+      assertEquals(expectedValues[i], builder.getRepeatedInt32(i));
+      assertEquals(expectedValues[i], builder.getRepeatedUint32(i));
+      assertEquals(expectedValues[i], builder.getRepeatedInt64(i));
+      assertEquals(expectedValues[i], builder.getRepeatedUint64(i));
+    }
+    
+    // Non-integers will still be rejected.
+    assertRejects("optionalInt32", "1.5");
+    assertRejects("optionalUint32", "1.5");
+    assertRejects("optionalInt64", "1.5");
+    assertRejects("optionalUint64", "1.5");
+  }
+  
   private void assertRejects(String name, String value) {
     TestAllTypes.Builder builder = TestAllTypes.newBuilder();
     try {
@@ -285,6 +317,7 @@ public class JsonFormatTest extends TestCase {
     TestAllTypes.Builder builder = TestAllTypes.newBuilder();
     // Both numeric form and string form are accepted.
     mergeFromJson("{\"" + name + "\":" + value + "}", builder);
+    builder.clear();
     mergeFromJson("{\"" + name + "\":\"" + value + "\"}", builder);
   }
   
@@ -370,84 +403,74 @@ public class JsonFormatTest extends TestCase {
     TestAllTypes message = builder.build();
     assertEquals(TestAllTypes.getDefaultInstance(), message);
     
-    // Repeated field elements can also be null.
-    builder = TestAllTypes.newBuilder();
-    mergeFromJson(
-        "{\n"
-        + "  \"repeatedInt32\": [null, null],\n"
-        + "  \"repeatedInt64\": [null, null],\n"
-        + "  \"repeatedUint32\": [null, null],\n"
-        + "  \"repeatedUint64\": [null, null],\n"
-        + "  \"repeatedSint32\": [null, null],\n"
-        + "  \"repeatedSint64\": [null, null],\n"
-        + "  \"repeatedFixed32\": [null, null],\n"
-        + "  \"repeatedFixed64\": [null, null],\n"
-        + "  \"repeatedSfixed32\": [null, null],\n"
-        + "  \"repeatedSfixed64\": [null, null],\n"
-        + "  \"repeatedFloat\": [null, null],\n"
-        + "  \"repeatedDouble\": [null, null],\n"
-        + "  \"repeatedBool\": [null, null],\n"
-        + "  \"repeatedString\": [null, null],\n"
-        + "  \"repeatedBytes\": [null, null],\n"
-        + "  \"repeatedNestedMessage\": [null, null],\n"
-        + "  \"repeatedNestedEnum\": [null, null]\n"
-        + "}", builder);
-    message = builder.build();
-    // "null" elements will be parsed to default values.
-    assertEquals(2, message.getRepeatedInt32Count());
-    assertEquals(0, message.getRepeatedInt32(0));
-    assertEquals(0, message.getRepeatedInt32(1));
-    assertEquals(2, message.getRepeatedInt32Count());
-    assertEquals(0, message.getRepeatedInt32(0));
-    assertEquals(0, message.getRepeatedInt32(1));
-    assertEquals(2, message.getRepeatedInt64Count());
-    assertEquals(0, message.getRepeatedInt64(0));
-    assertEquals(0, message.getRepeatedInt64(1));
-    assertEquals(2, message.getRepeatedUint32Count());
-    assertEquals(0, message.getRepeatedUint32(0));
-    assertEquals(0, message.getRepeatedUint32(1));
-    assertEquals(2, message.getRepeatedUint64Count());
-    assertEquals(0, message.getRepeatedUint64(0));
-    assertEquals(0, message.getRepeatedUint64(1));
-    assertEquals(2, message.getRepeatedSint32Count());
-    assertEquals(0, message.getRepeatedSint32(0));
-    assertEquals(0, message.getRepeatedSint32(1));
-    assertEquals(2, message.getRepeatedSint64Count());
-    assertEquals(0, message.getRepeatedSint64(0));
-    assertEquals(0, message.getRepeatedSint64(1));
-    assertEquals(2, message.getRepeatedFixed32Count());
-    assertEquals(0, message.getRepeatedFixed32(0));
-    assertEquals(0, message.getRepeatedFixed32(1));
-    assertEquals(2, message.getRepeatedFixed64Count());
-    assertEquals(0, message.getRepeatedFixed64(0));
-    assertEquals(0, message.getRepeatedFixed64(1));
-    assertEquals(2, message.getRepeatedSfixed32Count());
-    assertEquals(0, message.getRepeatedSfixed32(0));
-    assertEquals(0, message.getRepeatedSfixed32(1));
-    assertEquals(2, message.getRepeatedSfixed64Count());
-    assertEquals(0, message.getRepeatedSfixed64(0));
-    assertEquals(0, message.getRepeatedSfixed64(1));
-    assertEquals(2, message.getRepeatedFloatCount());
-    assertEquals(0f, message.getRepeatedFloat(0));
-    assertEquals(0f, message.getRepeatedFloat(1));
-    assertEquals(2, message.getRepeatedDoubleCount());
-    assertEquals(0.0, message.getRepeatedDouble(0));
-    assertEquals(0.0, message.getRepeatedDouble(1));
-    assertEquals(2, message.getRepeatedBoolCount());
-    assertFalse(message.getRepeatedBool(0));
-    assertFalse(message.getRepeatedBool(1));
-    assertEquals(2, message.getRepeatedStringCount());
-    assertTrue(message.getRepeatedString(0).isEmpty());
-    assertTrue(message.getRepeatedString(1).isEmpty());
-    assertEquals(2, message.getRepeatedBytesCount());
-    assertTrue(message.getRepeatedBytes(0).isEmpty());
-    assertTrue(message.getRepeatedBytes(1).isEmpty());
-    assertEquals(2, message.getRepeatedNestedMessageCount());
-    assertEquals(NestedMessage.getDefaultInstance(), message.getRepeatedNestedMessage(0));
-    assertEquals(NestedMessage.getDefaultInstance(), message.getRepeatedNestedMessage(1));
-    assertEquals(2, message.getRepeatedNestedEnumCount());
-    assertEquals(0, message.getRepeatedNestedEnumValue(0));
-    assertEquals(0, message.getRepeatedNestedEnumValue(1));
+    // Repeated field elements cannot be null.
+    try {
+      builder = TestAllTypes.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"repeatedInt32\": [null, null],\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
+    
+    try {
+      builder = TestAllTypes.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"repeatedNestedMessage\": [null, null],\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
+  }
+  
+  public void testParserRejectDuplicatedFields() throws Exception {
+    // TODO(xiaofeng): The parser we are currently using (GSON) will accept and keep the last
+    // one if multiple entries have the same name. This is not the desired behavior but it can
+    // only be fixed by using our own parser. Here we only test the cases where the names are
+    // different but still referring to the same field.
+    
+    // Duplicated optional fields. 
+    try {
+      TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+      mergeFromJson(
+          "{\n"
+              + "  \"optionalNestedMessage\": {},\n"
+              + "  \"optional_nested_message\": {}\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
+    
+    // Duplicated repeated fields.
+    try {
+      TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"repeatedNestedMessage\": [null, null],\n"
+          + "  \"repeated_nested_message\": [null, null]\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
+    
+    // Duplicated oneof fields.
+    try {
+      TestOneof.Builder builder = TestOneof.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"oneofInt32\": 1,\n"
+          + "  \"oneof_int32\": 2\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
   }
   
   public void testMapFields() throws Exception {
@@ -592,18 +615,30 @@ public class JsonFormatTest extends TestCase {
     assertRoundTripEquals(message);
   }
   
-  public void testMapNullValueIsDefault() throws Exception {
-    TestMap.Builder builder = TestMap.newBuilder();
-    mergeFromJson(
-        "{\n"
-        + "  \"int32ToInt32Map\": {\"1\": null},\n"
-        + "  \"int32ToMessageMap\": {\"2\": null}\n"
-        + "}", builder);
-    TestMap message = builder.build();
-    assertTrue(message.getInt32ToInt32Map().containsKey(1));
-    assertEquals(0, message.getInt32ToInt32Map().get(1).intValue());
-    assertTrue(message.getInt32ToMessageMap().containsKey(2));
-    assertEquals(0, message.getInt32ToMessageMap().get(2).getValue());
+  public void testMapNullValueIsRejected() throws Exception {
+    try {
+      TestMap.Builder builder = TestMap.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"int32ToInt32Map\": {null: 1},\n"
+          + "  \"int32ToMessageMap\": {null: 2}\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
+    
+    try {
+      TestMap.Builder builder = TestMap.newBuilder();
+      mergeFromJson(
+          "{\n"
+          + "  \"int32ToInt32Map\": {\"1\": null},\n"
+          + "  \"int32ToMessageMap\": {\"2\": null}\n"
+          + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
   }
   
   public void testParserAcceptNonQuotedObjectKey() throws Exception {
@@ -743,6 +778,15 @@ public class JsonFormatTest extends TestCase {
         + "  }\n"
         + "}", toJsonString(message));
     assertRoundTripEquals(message);
+    
+    builder = TestStruct.newBuilder();
+    builder.setValue(Value.newBuilder().setNullValueValue(0).build());
+    message = builder.build();
+    assertEquals(
+        "{\n"
+        + "  \"value\": null\n"
+        + "}", toJsonString(message));
+    assertRoundTripEquals(message);
   }
   
   public void testAnyFields() throws Exception {
@@ -891,6 +935,15 @@ public class JsonFormatTest extends TestCase {
         + "  }\n"
         + "}", printer.print(anyMessage));
     assertRoundTripEquals(anyMessage, registry);
+    Value.Builder valueBuilder = Value.newBuilder();
+    valueBuilder.setNumberValue(1);
+    anyMessage = Any.pack(valueBuilder.build());
+    assertEquals(
+        "{\n"
+        + "  \"@type\": \"type.googleapis.com/google.protobuf.Value\",\n"
+        + "  \"value\": 1.0\n"
+        + "}", printer.print(anyMessage));
+    assertRoundTripEquals(anyMessage, registry);
   }
   
   public void testParserMissingTypeUrl() throws Exception {
@@ -949,16 +1002,9 @@ public class JsonFormatTest extends TestCase {
   }
   
   public void testParserRejectInvalidBase64() throws Exception {
-    try {
-      TestAllTypes.Builder builder = TestAllTypes.newBuilder();
-      mergeFromJson(
-          "{\n"
-          + "  \"optionalBytes\": \"!@#$\"\n"
-          + "}", builder);
-      fail("Exception is expected.");
-    } catch (InvalidProtocolBufferException e) {
-      // Expected.
-    } 
+    assertRejects("optionalBytes", "!@#$");
+    // We use standard BASE64 with paddings.
+    assertRejects("optionalBytes", "AQI");
   }
   
   public void testParserRejectInvalidEnumValue() throws Exception {
@@ -973,4 +1019,138 @@ public class JsonFormatTest extends TestCase {
       // Expected.
     } 
   }
+
+  public void testCustomJsonName() throws Exception {
+    TestCustomJsonName message = TestCustomJsonName.newBuilder().setValue(12345).build();
+    assertEquals("{\n" + "  \"@value\": 12345\n" + "}", JsonFormat.printer().print(message));
+    assertRoundTripEquals(message);
+  }
+
+  public void testIncludingDefaultValueFields() throws Exception {
+    TestAllTypes message = TestAllTypes.getDefaultInstance();
+    assertEquals("{\n}", JsonFormat.printer().print(message));
+    assertEquals(
+        "{\n"
+            + "  \"optionalInt32\": 0,\n"
+            + "  \"optionalInt64\": \"0\",\n"
+            + "  \"optionalUint32\": 0,\n"
+            + "  \"optionalUint64\": \"0\",\n"
+            + "  \"optionalSint32\": 0,\n"
+            + "  \"optionalSint64\": \"0\",\n"
+            + "  \"optionalFixed32\": 0,\n"
+            + "  \"optionalFixed64\": \"0\",\n"
+            + "  \"optionalSfixed32\": 0,\n"
+            + "  \"optionalSfixed64\": \"0\",\n"
+            + "  \"optionalFloat\": 0.0,\n"
+            + "  \"optionalDouble\": 0.0,\n"
+            + "  \"optionalBool\": false,\n"
+            + "  \"optionalString\": \"\",\n"
+            + "  \"optionalBytes\": \"\",\n"
+            + "  \"optionalNestedEnum\": \"FOO\",\n"
+            + "  \"repeatedInt32\": [],\n"
+            + "  \"repeatedInt64\": [],\n"
+            + "  \"repeatedUint32\": [],\n"
+            + "  \"repeatedUint64\": [],\n"
+            + "  \"repeatedSint32\": [],\n"
+            + "  \"repeatedSint64\": [],\n"
+            + "  \"repeatedFixed32\": [],\n"
+            + "  \"repeatedFixed64\": [],\n"
+            + "  \"repeatedSfixed32\": [],\n"
+            + "  \"repeatedSfixed64\": [],\n"
+            + "  \"repeatedFloat\": [],\n"
+            + "  \"repeatedDouble\": [],\n"
+            + "  \"repeatedBool\": [],\n"
+            + "  \"repeatedString\": [],\n"
+            + "  \"repeatedBytes\": [],\n"
+            + "  \"repeatedNestedMessage\": [],\n"
+            + "  \"repeatedNestedEnum\": []\n"
+            + "}",
+        JsonFormat.printer().includingDefaultValueFields().print(message));
+
+    TestMap mapMessage = TestMap.getDefaultInstance();
+    assertEquals("{\n}", JsonFormat.printer().print(mapMessage));
+    assertEquals(
+        "{\n"
+            + "  \"int32ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"int64ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"uint32ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"uint64ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"sint32ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"sint64ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"fixed32ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"fixed64ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"sfixed32ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"sfixed64ToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"boolToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"stringToInt32Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToInt64Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToUint32Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToUint64Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToSint32Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToSint64Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToFixed32Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToFixed64Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToSfixed32Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToSfixed64Map\": {\n"
+            + "  },\n"
+            + "  \"int32ToFloatMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToDoubleMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToBoolMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToStringMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToBytesMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToMessageMap\": {\n"
+            + "  },\n"
+            + "  \"int32ToEnumMap\": {\n"
+            + "  }\n"
+            + "}",
+        JsonFormat.printer().includingDefaultValueFields().print(mapMessage));
+  }
+
+  public void testPreservingProtoFieldNames() throws Exception {
+    TestAllTypes message = TestAllTypes.newBuilder().setOptionalInt32(12345).build();
+    assertEquals("{\n" + "  \"optionalInt32\": 12345\n" + "}", JsonFormat.printer().print(message));
+    assertEquals(
+        "{\n" + "  \"optional_int32\": 12345\n" + "}",
+        JsonFormat.printer().preservingProtoFieldNames().print(message));
+
+    // The json_name field option is ignored when configured to use original proto field names.
+    TestCustomJsonName messageWithCustomJsonName =
+        TestCustomJsonName.newBuilder().setValue(12345).build();
+    assertEquals(
+        "{\n" + "  \"value\": 12345\n" + "}",
+        JsonFormat.printer().preservingProtoFieldNames().print(messageWithCustomJsonName));
+
+    // Parsers accept both original proto field names and lowerCamelCase names.
+    TestAllTypes.Builder builder = TestAllTypes.newBuilder();
+    JsonFormat.parser().merge("{\"optionalInt32\": 12345}", builder);
+    assertEquals(12345, builder.getOptionalInt32());
+    builder.clear();
+    JsonFormat.parser().merge("{\"optional_int32\": 54321}", builder);
+    assertEquals(54321, builder.getOptionalInt32());
+  }
 }
diff --git a/java/util/src/test/java/com/google/protobuf/util/TimeUtilTest.java b/java/util/src/test/java/com/google/protobuf/util/TimeUtilTest.java
index fe5617e1..4c31b2b3 100644
--- a/java/util/src/test/java/com/google/protobuf/util/TimeUtilTest.java
+++ b/java/util/src/test/java/com/google/protobuf/util/TimeUtilTest.java
@@ -38,6 +38,8 @@ import junit.framework.TestCase;
 import org.junit.Assert;
 
 import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.List;
 
 /** Unit tests for {@link TimeUtil}. */
 public class TimeUtilTest extends TestCase {
@@ -76,6 +78,71 @@ public class TimeUtilTest extends TestCase {
     assertEquals("1970-01-01T08:00:00.010Z", TimeUtil.toString(value));
   }
 
+  private volatile boolean stopParsingThreads = false;
+  private volatile String errorMessage = "";
+
+  private class ParseTimestampThread extends Thread {
+    private final String[] strings;
+    private final Timestamp[] values;
+    public ParseTimestampThread(String[] strings, Timestamp[] values) {
+      this.strings = strings;
+      this.values = values;
+    }
+
+    @Override
+    public void run() {
+      int index = 0;
+      while (!stopParsingThreads) {
+        Timestamp result;
+        try {
+          result = TimeUtil.parseTimestamp(strings[index]);
+        } catch (ParseException e) {
+          errorMessage = "Failed to parse timestamp: " + strings[index];
+          break;
+        }
+        if (result.getSeconds() != values[index].getSeconds()
+            || result.getNanos() != values[index].getNanos()) {
+          errorMessage = "Actual result: " + result.toString() + ", expected: "
+              + values[index].toString();
+          break;
+        }
+        index = (index + 1) % strings.length;
+      }
+    }
+  }
+
+  public void testTimestampConcurrentParsing() throws Exception {
+    String[] timestampStrings = new String[]{
+      "0001-01-01T00:00:00Z",
+      "9999-12-31T23:59:59.999999999Z",
+      "1970-01-01T00:00:00Z",
+      "1969-12-31T23:59:59.999Z",
+    };
+    Timestamp[] timestampValues = new Timestamp[timestampStrings.length];
+    for (int i = 0; i < timestampStrings.length; i++) {
+      timestampValues[i] = TimeUtil.parseTimestamp(timestampStrings[i]);
+    }
+
+    final int THREAD_COUNT = 16;
+    final int RUNNING_TIME = 5000;  // in milliseconds.
+    final List<Thread> threads = new ArrayList<Thread>();
+
+    stopParsingThreads = false;
+    errorMessage = "";
+    for (int i = 0; i < THREAD_COUNT; i++) {
+      Thread thread = new ParseTimestampThread(
+          timestampStrings, timestampValues);
+      thread.start();
+      threads.add(thread);
+    }
+    Thread.sleep(RUNNING_TIME);
+    stopParsingThreads = true;
+    for (Thread thread : threads) {
+      thread.join();
+    }
+    Assert.assertEquals("", errorMessage);
+  }
+
   public void testTimetampInvalidFormat() throws Exception {
     try {
       // Value too small.
diff --git a/java/util/src/test/java/com/google/protobuf/util/json_test.proto b/java/util/src/test/java/com/google/protobuf/util/json_test.proto
index b2753af6..023ec2ca 100644
--- a/java/util/src/test/java/com/google/protobuf/util/json_test.proto
+++ b/java/util/src/test/java/com/google/protobuf/util/json_test.proto
@@ -65,7 +65,7 @@ message TestAllTypes {
   float optional_float = 11;
   double optional_double = 12;
   bool optional_bool = 13;
-  string optional_string = 14;
+  string optional_string = 14 [enforce_utf8 = false];
   bytes optional_bytes = 15;
   NestedMessage optional_nested_message = 18;
   NestedEnum optional_nested_enum = 21;
@@ -84,12 +84,19 @@ message TestAllTypes {
   repeated float repeated_float = 41;
   repeated double repeated_double = 42;
   repeated bool repeated_bool = 43;
-  repeated string repeated_string = 44;
+  repeated string repeated_string = 44 [enforce_utf8 = false];
   repeated bytes repeated_bytes = 45;
   repeated NestedMessage repeated_nested_message = 48;
   repeated NestedEnum repeated_nested_enum = 51;
 }
 
+message TestOneof {
+  oneof oneof_field {
+    int32 oneof_int32 = 1;
+    TestAllTypes.NestedMessage oneof_nested_message = 2;
+  }
+}
+
 message TestMap {
   // Instead of testing all combinations (too many), we only make sure all
   // valid types have been used at least in one field as key and in one
@@ -105,7 +112,7 @@ message TestMap {
   map<sfixed32, int32> sfixed32_to_int32_map = 9;
   map<sfixed64, int32> sfixed64_to_int32_map = 10;
   map<bool, int32> bool_to_int32_map = 11;
-  map<string, int32> string_to_int32_map = 12;
+  map<string, int32> string_to_int32_map = 12 [enforce_utf8 = false];
 
   map<int32, int64> int32_to_int64_map = 101;
   map<int32, uint32> int32_to_uint32_map = 102;
@@ -119,7 +126,7 @@ message TestMap {
   map<int32, float> int32_to_float_map = 110;
   map<int32, double> int32_to_double_map = 111;
   map<int32, bool> int32_to_bool_map = 112;
-  map<int32, string> int32_to_string_map = 113;
+  map<int32, string> int32_to_string_map = 113 [enforce_utf8 = false];
   map<int32, bytes> int32_to_bytes_map = 114;
   map<int32, TestAllTypes.NestedMessage> int32_to_message_map = 115;
   map<int32, TestAllTypes.NestedEnum> int32_to_enum_map = 116;
@@ -151,8 +158,13 @@ message TestFieldMask {
 
 message TestStruct {
   google.protobuf.Struct struct_value = 1;
+  google.protobuf.Value value = 2;
 }
 
 message TestAny {
   google.protobuf.Any any_value = 1;
 }
+
+message TestCustomJsonName {
+  int32 value = 1 [json_name = "@value"];
+}
diff --git a/js/binary/arith.js b/js/binary/arith.js
new file mode 100644
index 00000000..70257de7
--- /dev/null
+++ b/js/binary/arith.js
@@ -0,0 +1,413 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains helper code used by jspb.utils to
+ * handle 64-bit integer conversion to/from strings.
+ *
+ * @author cfallin@google.com (Chris Fallin)
+ *
+ * TODO(haberman): move this to javascript/closure/math?
+ */
+
+goog.provide('jspb.arith.Int64');
+goog.provide('jspb.arith.UInt64');
+
+/**
+ * UInt64 implements some 64-bit arithmetic routines necessary for properly
+ * handling 64-bit integer fields. It implements lossless integer arithmetic on
+ * top of JavaScript's number type, which has only 53 bits of precision, by
+ * representing 64-bit integers as two 32-bit halves.
+ *
+ * @param {number} lo The low 32 bits.
+ * @param {number} hi The high 32 bits.
+ * @constructor
+ */
+jspb.arith.UInt64 = function(lo, hi) {
+  /**
+   * The low 32 bits.
+   * @public {number}
+   */
+  this.lo = lo;
+  /**
+   * The high 32 bits.
+   * @public {number}
+   */
+  this.hi = hi;
+};
+
+
+/**
+ * Compare two 64-bit numbers. Returns -1 if the first is
+ * less, +1 if the first is greater, or 0 if both are equal.
+ * @param {!jspb.arith.UInt64} other
+ * @return {number}
+ */
+jspb.arith.UInt64.prototype.cmp = function(other) {
+  if (this.hi < other.hi || (this.hi == other.hi && this.lo < other.lo)) {
+    return -1;
+  } else if (this.hi == other.hi && this.lo == other.lo) {
+    return 0;
+  } else {
+    return 1;
+  }
+};
+
+
+/**
+ * Right-shift this number by one bit.
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.rightShift = function() {
+  var hi = this.hi >>> 1;
+  var lo = (this.lo >>> 1) | ((this.hi & 1) << 31);
+  return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Left-shift this number by one bit.
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.leftShift = function() {
+  var lo = this.lo << 1;
+  var hi = (this.hi << 1) | (this.lo >>> 31);
+  return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Test the MSB.
+ * @return {boolean}
+ */
+jspb.arith.UInt64.prototype.msb = function() {
+  return !!(this.hi & 0x80000000);
+};
+
+
+/**
+ * Test the LSB.
+ * @return {boolean}
+ */
+jspb.arith.UInt64.prototype.lsb = function() {
+  return !!(this.lo & 1);
+};
+
+
+/**
+ * Test whether this number is zero.
+ * @return {boolean}
+ */
+jspb.arith.UInt64.prototype.zero = function() {
+  return this.lo == 0 && this.hi == 0;
+};
+
+
+/**
+ * Add two 64-bit numbers to produce a 64-bit number.
+ * @param {!jspb.arith.UInt64} other
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.add = function(other) {
+  var lo = ((this.lo + other.lo) & 0xffffffff) >>> 0;
+  var hi =
+      (((this.hi + other.hi) & 0xffffffff) >>> 0) +
+      (((this.lo + other.lo) >= 0x100000000) ? 1 : 0);
+  return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Subtract two 64-bit numbers to produce a 64-bit number.
+ * @param {!jspb.arith.UInt64} other
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.sub = function(other) {
+  var lo = ((this.lo - other.lo) & 0xffffffff) >>> 0;
+  var hi =
+      (((this.hi - other.hi) & 0xffffffff) >>> 0) -
+      (((this.lo - other.lo) < 0) ? 1 : 0);
+  return new jspb.arith.UInt64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Multiply two 32-bit numbers to produce a 64-bit number.
+ * @param {number} a The first integer:  must be in [0, 2^32-1).
+ * @param {number} b The second integer: must be in [0, 2^32-1).
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.mul32x32 = function(a, b) {
+  // Directly multiplying two 32-bit numbers may produce up to 64 bits of
+  // precision, thus losing precision because of the 53-bit mantissa of
+  // JavaScript numbers. So we multiply with 16-bit digits (radix 65536)
+  // instead.
+  var aLow = (a & 0xffff);
+  var aHigh = (a >>> 16);
+  var bLow = (b & 0xffff);
+  var bHigh = (b >>> 16);
+  var productLow =
+      // 32-bit result, result bits 0-31, take all 32 bits
+      (aLow * bLow) +
+      // 32-bit result, result bits 16-47, take bottom 16 as our top 16
+      ((aLow * bHigh) & 0xffff) * 0x10000 +
+      // 32-bit result, result bits 16-47, take bottom 16 as our top 16
+      ((aHigh * bLow) & 0xffff) * 0x10000;
+  var productHigh =
+      // 32-bit result, result bits 32-63, take all 32 bits
+      (aHigh * bHigh) +
+      // 32-bit result, result bits 16-47, take top 16 as our bottom 16
+      ((aLow * bHigh) >>> 16) +
+      // 32-bit result, result bits 16-47, take top 16 as our bottom 16
+      ((aHigh * bLow) >>> 16);
+
+  // Carry. Note that we actually have up to *two* carries due to addition of
+  // three terms.
+  while (productLow >= 0x100000000) {
+    productLow -= 0x100000000;
+    productHigh += 1;
+  }
+
+  return new jspb.arith.UInt64(productLow >>> 0, productHigh >>> 0);
+};
+
+
+/**
+ * Multiply this number by a 32-bit number, producing a 96-bit number, then
+ * truncate the top 32 bits.
+ * @param {number} a The multiplier.
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.mul = function(a) {
+  // Produce two parts: at bits 0-63, and 32-95.
+  var lo = jspb.arith.UInt64.mul32x32(this.lo, a);
+  var hi = jspb.arith.UInt64.mul32x32(this.hi, a);
+  // Left-shift hi by 32 bits, truncating its top bits. The parts will then be
+  // aligned for addition.
+  hi.hi = hi.lo;
+  hi.lo = 0;
+  return lo.add(hi);
+};
+
+
+/**
+ * Divide a 64-bit number by a 32-bit number to produce a
+ * 64-bit quotient and a 32-bit remainder.
+ * @param {number} _divisor
+ * @return {Array.<jspb.arith.UInt64>} array of [quotient, remainder],
+ * unless divisor is 0, in which case an empty array is returned.
+ */
+jspb.arith.UInt64.prototype.div = function(_divisor) {
+  if (_divisor == 0) {
+    return [];
+  }
+
+  // We perform long division using a radix-2 algorithm, for simplicity (i.e.,
+  // one bit at a time). TODO: optimize to a radix-2^32 algorithm, taking care
+  // to get the variable shifts right.
+  var quotient = new jspb.arith.UInt64(0, 0);
+  var remainder = new jspb.arith.UInt64(this.lo, this.hi);
+  var divisor = new jspb.arith.UInt64(_divisor, 0);
+  var unit = new jspb.arith.UInt64(1, 0);
+
+  // Left-shift the divisor and unit until the high bit of divisor is set.
+  while (!divisor.msb()) {
+    divisor = divisor.leftShift();
+    unit = unit.leftShift();
+  }
+
+  // Perform long division one bit at a time.
+  while (!unit.zero()) {
+    // If divisor < remainder, add unit to quotient and subtract divisor from
+    // remainder.
+    if (divisor.cmp(remainder) <= 0) {
+      quotient = quotient.add(unit);
+      remainder = remainder.sub(divisor);
+    }
+    // Right-shift the divisor and unit.
+    divisor = divisor.rightShift();
+    unit = unit.rightShift();
+  }
+
+  return [quotient, remainder];
+};
+
+
+/**
+ * Convert a 64-bit number to a string.
+ * @return {string}
+ * @override
+ */
+jspb.arith.UInt64.prototype.toString = function() {
+  var result = '';
+  var num = this;
+  while (!num.zero()) {
+    var divResult = num.div(10);
+    var quotient = divResult[0], remainder = divResult[1];
+    result = remainder.lo + result;
+    num = quotient;
+  }
+  if (result == '') {
+    result = '0';
+  }
+  return result;
+};
+
+
+/**
+ * Parse a string into a 64-bit number. Returns `null` on a parse error.
+ * @param {string} s
+ * @return {?jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.fromString = function(s) {
+  var result = new jspb.arith.UInt64(0, 0);
+  // optimization: reuse this instance for each digit.
+  var digit64 = new jspb.arith.UInt64(0, 0);
+  for (var i = 0; i < s.length; i++) {
+    if (s[i] < '0' || s[i] > '9') {
+      return null;
+    }
+    var digit = parseInt(s[i], 10);
+    digit64.lo = digit;
+    result = result.mul(10).add(digit64);
+  }
+  return result;
+};
+
+
+/**
+ * Make a copy of the uint64.
+ * @return {!jspb.arith.UInt64}
+ */
+jspb.arith.UInt64.prototype.clone = function() {
+  return new jspb.arith.UInt64(this.lo, this.hi);
+};
+
+
+/**
+ * Int64 is like UInt64, but modifies string conversions to interpret the stored
+ * 64-bit value as a twos-complement-signed integer. It does *not* support the
+ * full range of operations that UInt64 does: only add, subtract, and string
+ * conversions.
+ *
+ * N.B. that multiply and divide routines are *NOT* supported. They will throw
+ * exceptions. (They are not necessary to implement string conversions, which
+ * are the only operations we really need in jspb.)
+ *
+ * @param {number} lo The low 32 bits.
+ * @param {number} hi The high 32 bits.
+ * @constructor
+ */
+jspb.arith.Int64 = function(lo, hi) {
+  /**
+   * The low 32 bits.
+   * @public {number}
+   */
+  this.lo = lo;
+  /**
+   * The high 32 bits.
+   * @public {number}
+   */
+  this.hi = hi;
+};
+
+
+/**
+ * Add two 64-bit numbers to produce a 64-bit number.
+ * @param {!jspb.arith.Int64} other
+ * @return {!jspb.arith.Int64}
+ */
+jspb.arith.Int64.prototype.add = function(other) {
+  var lo = ((this.lo + other.lo) & 0xffffffff) >>> 0;
+  var hi =
+      (((this.hi + other.hi) & 0xffffffff) >>> 0) +
+      (((this.lo + other.lo) >= 0x100000000) ? 1 : 0);
+  return new jspb.arith.Int64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Subtract two 64-bit numbers to produce a 64-bit number.
+ * @param {!jspb.arith.Int64} other
+ * @return {!jspb.arith.Int64}
+ */
+jspb.arith.Int64.prototype.sub = function(other) {
+  var lo = ((this.lo - other.lo) & 0xffffffff) >>> 0;
+  var hi =
+      (((this.hi - other.hi) & 0xffffffff) >>> 0) -
+      (((this.lo - other.lo) < 0) ? 1 : 0);
+  return new jspb.arith.Int64(lo >>> 0, hi >>> 0);
+};
+
+
+/**
+ * Make a copy of the int64.
+ * @return {!jspb.arith.Int64}
+ */
+jspb.arith.Int64.prototype.clone = function() {
+  return new jspb.arith.Int64(this.lo, this.hi);
+};
+
+
+/**
+ * Convert a 64-bit number to a string.
+ * @return {string}
+ * @override
+ */
+jspb.arith.Int64.prototype.toString = function() {
+  // If the number is negative, find its twos-complement inverse.
+  var sign = (this.hi & 0x80000000) != 0;
+  var num = new jspb.arith.UInt64(this.lo, this.hi);
+  if (sign) {
+    num = new jspb.arith.UInt64(0, 0).sub(num);
+  }
+  return (sign ? '-' : '') + num.toString();
+};
+
+
+/**
+ * Parse a string into a 64-bit number. Returns `null` on a parse error.
+ * @param {string} s
+ * @return {?jspb.arith.Int64}
+ */
+jspb.arith.Int64.fromString = function(s) {
+  var hasNegative = (s.length > 0 && s[0] == '-');
+  if (hasNegative) {
+    s = s.substring(1);
+  }
+  var num = jspb.arith.UInt64.fromString(s);
+  if (num === null) {
+    return null;
+  }
+  if (hasNegative) {
+    num = new jspb.arith.UInt64(0, 0).sub(num);
+  }
+  return new jspb.arith.Int64(num.lo, num.hi);
+};
diff --git a/js/binary/arith_test.js b/js/binary/arith_test.js
new file mode 100644
index 00000000..89796bf7
--- /dev/null
+++ b/js/binary/arith_test.js
@@ -0,0 +1,355 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Test cases for Int64-manipulation functions.
+ *
+ * Test suite is written using Jasmine -- see http://jasmine.github.io/
+ *
+ * @author cfallin@google.com (Chris Fallin)
+ */
+
+goog.require('goog.testing.asserts');
+goog.require('jspb.arith.Int64');
+goog.require('jspb.arith.UInt64');
+
+
+describe('binaryArithTest', function() {
+  /**
+   * Tests comparison operations.
+   */
+  it('testCompare', function() {
+    var a = new jspb.arith.UInt64(1234, 5678);
+    var b = new jspb.arith.UInt64(1234, 5678);
+    assertEquals(a.cmp(b), 0);
+    assertEquals(b.cmp(a), 0);
+    b.lo -= 1;
+    assertEquals(a.cmp(b), 1);
+    assertEquals(b.cmp(a), -1);
+    b.lo += 2;
+    assertEquals(a.cmp(b), -1);
+    assertEquals(b.cmp(a), 1);
+    b.lo = a.lo;
+    b.hi = a.hi - 1;
+    assertEquals(a.cmp(b), 1);
+    assertEquals(b.cmp(a), -1);
+
+    assertEquals(a.zero(), false);
+    assertEquals(a.msb(), false);
+    assertEquals(a.lsb(), false);
+    a.hi = 0;
+    a.lo = 0;
+    assertEquals(a.zero(), true);
+    a.hi = 0x80000000;
+    assertEquals(a.zero(), false);
+    assertEquals(a.msb(), true);
+    a.lo = 0x00000001;
+    assertEquals(a.lsb(), true);
+  });
+
+
+  /**
+   * Tests shifts.
+   */
+  it('testShifts', function() {
+    var a = new jspb.arith.UInt64(1, 0);
+    assertEquals(a.lo, 1);
+    assertEquals(a.hi, 0);
+    var orig = a;
+    a = a.leftShift();
+    assertEquals(orig.lo, 1);  // original unmodified.
+    assertEquals(orig.hi, 0);
+    assertEquals(a.lo, 2);
+    assertEquals(a.hi, 0);
+    a = a.leftShift();
+    assertEquals(a.lo, 4);
+    assertEquals(a.hi, 0);
+    for (var i = 0; i < 29; i++) {
+      a = a.leftShift();
+    }
+    assertEquals(a.lo, 0x80000000);
+    assertEquals(a.hi, 0);
+    a = a.leftShift();
+    assertEquals(a.lo, 0);
+    assertEquals(a.hi, 1);
+    a = a.leftShift();
+    assertEquals(a.lo, 0);
+    assertEquals(a.hi, 2);
+    a = a.rightShift();
+    a = a.rightShift();
+    assertEquals(a.lo, 0x80000000);
+    assertEquals(a.hi, 0);
+    a = a.rightShift();
+    assertEquals(a.lo, 0x40000000);
+    assertEquals(a.hi, 0);
+  });
+
+
+  /**
+   * Tests additions.
+   */
+  it('testAdd', function() {
+    var a = new jspb.arith.UInt64(/* lo = */ 0x89abcdef,
+                                         /* hi = */ 0x01234567);
+    var b = new jspb.arith.UInt64(/* lo = */ 0xff52ab91,
+                                         /* hi = */ 0x92fa2123);
+    // Addition with carry.
+    var c = a.add(b);
+    assertEquals(a.lo, 0x89abcdef);  // originals unmodified.
+    assertEquals(a.hi, 0x01234567);
+    assertEquals(b.lo, 0xff52ab91);
+    assertEquals(b.hi, 0x92fa2123);
+    assertEquals(c.lo, 0x88fe7980);
+    assertEquals(c.hi, 0x941d668b);
+
+    // Simple addition without carry.
+    a.lo = 2;
+    a.hi = 0;
+    b.lo = 3;
+    b.hi = 0;
+    c = a.add(b);
+    assertEquals(c.lo, 5);
+    assertEquals(c.hi, 0);
+  });
+
+
+  /**
+   * Test subtractions.
+   */
+  it('testSub', function() {
+    var kLength = 10;
+    var hiValues = [0x1682ef32,
+                    0x583902f7,
+                    0xb62f5955,
+                    0x6ea99bbf,
+                    0x25a39c20,
+                    0x0700a08b,
+                    0x00f7304d,
+                    0x91a5b5af,
+                    0x89077fd2,
+                    0xe09e347c];
+    var loValues = [0xe1538b18,
+                    0xbeacd556,
+                    0x74100758,
+                    0x96e3cb26,
+                    0x56c37c3f,
+                    0xe00b3f7d,
+                    0x859f25d7,
+                    0xc2ee614a,
+                    0xe1d21cd7,
+                    0x30aae6a4];
+    for (var i = 0; i < kLength; i++) {
+      for (var j = 0; j < kLength; j++) {
+        var a = new jspb.arith.UInt64(loValues[i], hiValues[j]);
+        var b = new jspb.arith.UInt64(loValues[j], hiValues[i]);
+        var c = a.add(b).sub(b);
+        assertEquals(c.hi, a.hi);
+        assertEquals(c.lo, a.lo);
+      }
+    }
+  });
+
+
+  /**
+   * Tests 32-by-32 multiplication.
+   */
+  it('testMul32x32', function() {
+    var testData = [
+      // a        b          low(a*b)   high(a*b)
+      [0xc0abe2f8, 0x1607898a, 0x5de711b0, 0x109471b8],
+      [0x915eb3cb, 0x4fb66d0e, 0xbd0d441a, 0x2d43d0bc],
+      [0xfe4efe70, 0x80b48c37, 0xbcddea10, 0x7fdada0c],
+      [0xe222fd4a, 0xe43d524a, 0xd5e0eb64, 0xc99d549c],
+      [0xd171f469, 0xb94ebd01, 0x4be17969, 0x979bc4fa],
+      [0x829cc1df, 0xe2598b38, 0xf4157dc8, 0x737c12ad],
+      [0xf10c3767, 0x8382881e, 0x942b3612, 0x7bd428b8],
+      [0xb0f6dd24, 0x232597e1, 0x079c98a4, 0x184bbce7],
+      [0xfcdb05a7, 0x902f55bc, 0x636199a4, 0x8e69f412],
+      [0x0dd0bfa9, 0x916e27b1, 0x6e2542d9, 0x07d92e65]
+    ];
+
+    for (var i = 0; i < testData.length; i++) {
+      var a = testData[i][0] >>> 0;
+      var b = testData[i][1] >>> 0;
+      var cLow = testData[i][2] >>> 0;
+      var cHigh = testData[i][3] >>> 0;
+      var c = jspb.arith.UInt64.mul32x32(a, b);
+      assertEquals(c.lo, cLow);
+      assertEquals(c.hi, cHigh);
+    }
+  });
+
+
+  /**
+   * Tests 64-by-32 multiplication.
+   */
+  it('testMul', function() {
+    // 64x32 bits produces 96 bits of product. The multiplication function under
+    // test truncates the top 32 bits, so we compare against a 64-bit expected
+    // product.
+    var testData = [
+      // low(a)   high(a)               low(a*b)   high(a*b)
+      [0xec10955b, 0x360eb168, 0x4b7f3f5b, 0xbfcb7c59, 0x9517da5f],
+      [0x42b000fc, 0x9d101642, 0x6fa1ab72, 0x2584c438, 0x6a9e6d2b],
+      [0xf42d4fb4, 0xae366403, 0xa65a1000, 0x92434000, 0x1ff978df],
+      [0x17e2f56b, 0x25487693, 0xf13f98c7, 0x73794e2d, 0xa96b0c6a],
+      [0x492f241f, 0x76c0eb67, 0x7377ac44, 0xd4336c3c, 0xfc4b1ebe],
+      [0xd6b92321, 0xe184fa48, 0xd6e76904, 0x93141584, 0xcbf44da1],
+      [0x4bf007ea, 0x968c0a9e, 0xf5e4026a, 0x4fdb1ae4, 0x61b9fb7d],
+      [0x10a83be7, 0x2d685ba6, 0xc9e5fb7f, 0x2ad43499, 0x3742473d],
+      [0x2f261829, 0x1aca681a, 0x3d3494e3, 0x8213205b, 0x283719f8],
+      [0xe4f2ce21, 0x2e74b7bd, 0xd801b38b, 0xbc17feeb, 0xc6c44e0f]
+    ];
+
+    for (var i = 0; i < testData.length; i++) {
+      var a = new jspb.arith.UInt64(testData[i][0], testData[i][1]);
+      var prod = a.mul(testData[i][2]);
+      assertEquals(prod.lo, testData[i][3]);
+      assertEquals(prod.hi, testData[i][4]);
+    }
+  });
+
+
+  /**
+   * Tests 64-div-by-32 division.
+   */
+  it('testDiv', function() {
+    // Compute a/b, yielding quot = a/b and rem = a%b.
+    var testData = [
+      // --- divisors in (0, 2^32-1) to test full divisor range
+      // low(a)   high(a)    b          low(quot)  high(quot) rem
+      [0x712443f1, 0xe85cefcc, 0xc1a7050b, 0x332c79ad, 0x00000001, 0x92ffa882],
+      [0x11912915, 0xb2699eb5, 0x30467cbe, 0xb21b4be4, 0x00000003, 0x283465dd],
+      [0x0d917982, 0x201f2a6e, 0x3f35bf03, 0x8217c8e4, 0x00000000, 0x153402d6],
+      [0xa072c108, 0x74020c96, 0xc60568fd, 0x95f9613e, 0x00000000, 0x3f4676c2],
+      [0xd845d5d8, 0xcdd235c4, 0x20426475, 0x6154e78b, 0x00000006, 0x202fb751],
+      [0xa4dbf71f, 0x9e90465e, 0xf08e022f, 0xa8be947f, 0x00000000, 0xbe43b5ce],
+      [0x3dbe627f, 0xa791f4b9, 0x28a5bd89, 0x1f5dfe93, 0x00000004, 0x02bf9ed4],
+      [0x5c1c53ee, 0xccf5102e, 0x198576e7, 0x07e3ae31, 0x00000008, 0x02ea8fb7],
+      [0xfef1e581, 0x04714067, 0xca6540c1, 0x059e73ec, 0x00000000, 0x31658095],
+      [0x1e2dd90c, 0x13dd6667, 0x8b2184c3, 0x248d1a42, 0x00000000, 0x4ca6d0c6],
+      // --- divisors in (0, 2^16-1) to test larger quotient high-words
+      // low(a)   high(a)    b          low(quot)  high(quot) rem
+      [0x86722b47, 0x2cd57c9a, 0x00003123, 0x2ae41b7a, 0x0000e995, 0x00000f99],
+      [0x1dd7884c, 0xf5e839bc, 0x00009eeb, 0x5c886242, 0x00018c21, 0x000099b6],
+      [0x5c53d625, 0x899fc7e5, 0x000087d7, 0xd625007a, 0x0001035c, 0x000019af],
+      [0x6932d932, 0x9d0a5488, 0x000051fb, 0x9d976143, 0x0001ea63, 0x00004981],
+      [0x4d18bb85, 0x0c92fb31, 0x00001d9f, 0x03265ab4, 0x00006cac, 0x000001b9],
+      [0xbe756768, 0xdea67ccb, 0x00008a03, 0x58add442, 0x00019cff, 0x000056a2],
+      [0xe2466f9a, 0x2521f114, 0x0000c350, 0xa0c0860d, 0x000030ab, 0x0000a48a],
+      [0xf00ddad1, 0xe2f5446a, 0x00002cfc, 0x762697a6, 0x00050b96, 0x00000b69],
+      [0xa879152a, 0x0a70e0a5, 0x00007cdf, 0xb44151b3, 0x00001567, 0x0000363d],
+      [0x7179a74c, 0x46083fff, 0x0000253c, 0x4d39ba6e, 0x0001e17f, 0x00000f84]
+    ];
+
+    for (var i = 0; i < testData.length; i++) {
+      var a = new jspb.arith.UInt64(testData[i][0], testData[i][1]);
+      var result = a.div(testData[i][2]);
+      var quotient = result[0];
+      var remainder = result[1];
+      assertEquals(quotient.lo, testData[i][3]);
+      assertEquals(quotient.hi, testData[i][4]);
+      assertEquals(remainder.lo, testData[i][5]);
+    }
+  });
+
+
+  /**
+   * Tests .toString() and .fromString().
+   */
+  it('testStrings', function() {
+    var testData = [
+        [0x5e84c935, 0xcae33d0e, '14619595947299359029'],
+        [0x62b3b8b8, 0x93480544, '10612738313170434232'],
+        [0x319bfb13, 0xc01c4172, '13843011313344445203'],
+        [0x5b8a65fb, 0xa5885b31, '11927883880638080507'],
+        [0x6bdb80f1, 0xb0d1b16b, '12741159895737008369'],
+        [0x4b82b442, 0x2e0d8c97, '3318463081876730946'],
+        [0x780d5208, 0x7d76752c, '9040542135845999112'],
+        [0x2e46800f, 0x0993778d, '690026616168284175'],
+        [0xf00a7e32, 0xcd8e3931, '14811839111111540274'],
+        [0x1baeccd6, 0x923048c4, '10533999535534820566'],
+        [0x03669d29, 0xbff3ab72, '13831587386756603177'],
+        [0x2526073e, 0x01affc81, '121593346566522686'],
+        [0xc24244e0, 0xd7f40d0e, '15561076969511732448'],
+        [0xc56a341e, 0xa68b66a7, '12000798502816461854'],
+        [0x8738d64d, 0xbfe78604, '13828168534871037517'],
+        [0x5baff03b, 0xd7572aea, '15516918227177304123'],
+        [0x4a843d8a, 0x864e132b, '9677693725920476554'],
+        [0x25b4e94d, 0x22b54dc6, '2500990681505655117'],
+        [0x6bbe664b, 0x55a5cc0e, '6171563226690381387'],
+        [0xee916c81, 0xb00aabb3, '12685140089732426881']
+    ];
+
+    for (var i = 0; i < testData.length; i++) {
+      var a = new jspb.arith.UInt64(testData[i][0], testData[i][1]);
+      var roundtrip = jspb.arith.UInt64.fromString(a.toString());
+      assertEquals(roundtrip.lo, a.lo);
+      assertEquals(roundtrip.hi, a.hi);
+      assertEquals(a.toString(), testData[i][2]);
+    }
+  });
+
+
+  /**
+   * Tests signed Int64s. These are built on UInt64s, so we only need to test
+   * the explicit overrides: .toString() and .fromString().
+   */
+  it('testSignedInt64', function() {
+    var testStrings = [
+        '-7847499644178593666',
+        '3771946501229139523',
+        '2872856549054995060',
+        '-5780049594274350904',
+        '3383785956695105201',
+        '2973055184857072610',
+        '-3879428459215627206',
+        '4589812431064156631',
+        '8484075557333689940',
+        '1075325817098092407',
+        '-4346697501012292314',
+        '2488620459718316637',
+        '6112655187423520672',
+        '-3655278273928612104',
+        '3439154019435803196',
+        '1004112478843763757',
+        '-6587790776614368413',
+        '664320065099714586',
+        '4760412909973292912',
+        '-7911903989602274672'
+    ];
+
+    for (var i = 0; i < testStrings.length; i++) {
+      var roundtrip =
+          jspb.arith.Int64.fromString(testStrings[i]).toString();
+      assertEquals(roundtrip, testStrings[i]);
+    }
+  });
+});
diff --git a/js/binary/constants.js b/js/binary/constants.js
new file mode 100644
index 00000000..a976e0b6
--- /dev/null
+++ b/js/binary/constants.js
@@ -0,0 +1,320 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains constants and typedefs used by
+ * jspb.BinaryReader and BinaryWriter.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.AnyFieldType');
+goog.provide('jspb.BinaryConstants');
+goog.provide('jspb.BinaryMessage');
+goog.provide('jspb.BuilderFunction');
+goog.provide('jspb.ByteSource');
+goog.provide('jspb.ClonerFunction');
+goog.provide('jspb.ConstBinaryMessage');
+goog.provide('jspb.ReaderFunction');
+goog.provide('jspb.RecyclerFunction');
+goog.provide('jspb.WriterFunction');
+
+goog.forwardDeclare('jspb.Message');
+goog.forwardDeclare('jsproto.BinaryExtension');
+
+
+
+/**
+ * Base interface class for all const messages. Does __not__ define any
+ * methods, as doing so on a widely-used interface defeats dead-code
+ * elimination.
+ * @interface
+ */
+jspb.ConstBinaryMessage = function() {};
+
+
+
+/**
+ * Base interface class for all messages. Does __not__ define any methods, as
+ * doing so on a widely-used interface defeats dead-code elimination.
+ * @interface
+ * @extends {jspb.ConstBinaryMessage}
+ */
+jspb.BinaryMessage = function() {};
+
+
+/**
+ * The types convertible to Uint8Arrays. Strings are assumed to be
+ * base64-encoded.
+ * @typedef {ArrayBuffer|Uint8Array|Array<number>|string}
+ */
+jspb.ByteSource;
+
+
+/**
+ * A field in jspb can be a scalar, a block of bytes, another proto, or an
+ * array of any of the above.
+ * @typedef {boolean|number|string|Uint8Array|
+             jspb.BinaryMessage|jsproto.BinaryExtension|
+             Array<jspb.AnyFieldType>}
+ */
+jspb.AnyFieldType;
+
+
+/**
+ * A builder function creates an instance of a message object.
+ * @typedef {function():!jspb.BinaryMessage}
+ */
+jspb.BuilderFunction;
+
+
+/**
+ * A cloner function creates a deep copy of a message object.
+ * @typedef {function(jspb.ConstBinaryMessage):jspb.BinaryMessage}
+ */
+jspb.ClonerFunction;
+
+
+/**
+ * A recycler function destroys an instance of a message object.
+ * @typedef {function(!jspb.BinaryMessage):void}
+ */
+jspb.RecyclerFunction;
+
+
+/**
+ * A reader function initializes a message using data from a BinaryReader.
+ * @typedef {function(!jspb.BinaryMessage, !jspb.BinaryReader):void}
+ */
+jspb.ReaderFunction;
+
+
+/**
+ * A writer function serializes a message to a BinaryWriter.
+ * @typedef {!function(!jspb.Message, !jspb.BinaryWriter):void |
+ *           !function(!jspb.ConstBinaryMessage, !jspb.BinaryWriter):void}
+ */
+jspb.WriterFunction;
+
+
+/**
+ * Field type codes, taken from proto2/public/wire_format_lite.h.
+ * @enum {number}
+ */
+jspb.BinaryConstants.FieldType = {
+  INVALID: -1,
+  DOUBLE: 1,
+  FLOAT: 2,
+  INT64: 3,
+  UINT64: 4,
+  INT32: 5,
+  FIXED64: 6,
+  FIXED32: 7,
+  BOOL: 8,
+  STRING: 9,
+  GROUP: 10,
+  MESSAGE: 11,
+  BYTES: 12,
+  UINT32: 13,
+  ENUM: 14,
+  SFIXED32: 15,
+  SFIXED64: 16,
+  SINT32: 17,
+  SINT64: 18,
+
+  // Extended types for Javascript
+
+  FHASH64: 30, // 64-bit hash string, fixed-length encoding.
+  VHASH64: 31  // 64-bit hash string, varint encoding.
+};
+
+
+/**
+ * Wire-format type codes, taken from proto2/public/wire_format_lite.h.
+ * @enum {number}
+ */
+jspb.BinaryConstants.WireType = {
+  INVALID: -1,
+  VARINT: 0,
+  FIXED64: 1,
+  DELIMITED: 2,
+  START_GROUP: 3,
+  END_GROUP: 4,
+  FIXED32: 5
+};
+
+
+/**
+ * Translates field type to wire type.
+ * @param {jspb.BinaryConstants.FieldType} fieldType
+ * @return {jspb.BinaryConstants.WireType}
+ */
+jspb.BinaryConstants.FieldTypeToWireType = function(fieldType) {
+  var fieldTypes = jspb.BinaryConstants.FieldType;
+  var wireTypes = jspb.BinaryConstants.WireType;
+  switch (fieldType) {
+    case fieldTypes.INT32:
+    case fieldTypes.INT64:
+    case fieldTypes.UINT32:
+    case fieldTypes.UINT64:
+    case fieldTypes.SINT32:
+    case fieldTypes.SINT64:
+    case fieldTypes.BOOL:
+    case fieldTypes.ENUM:
+    case fieldTypes.VHASH64:
+      return wireTypes.VARINT;
+
+    case fieldTypes.DOUBLE:
+    case fieldTypes.FIXED64:
+    case fieldTypes.SFIXED64:
+    case fieldTypes.FHASH64:
+      return wireTypes.FIXED64;
+
+    case fieldTypes.STRING:
+    case fieldTypes.MESSAGE:
+    case fieldTypes.BYTES:
+      return wireTypes.DELIMITED;
+
+    case fieldTypes.FLOAT:
+    case fieldTypes.FIXED32:
+    case fieldTypes.SFIXED32:
+      return wireTypes.FIXED32;
+
+    case fieldTypes.INVALID:
+    case fieldTypes.GROUP:
+    default:
+      return wireTypes.INVALID;
+  }
+};
+
+
+/**
+ * Flag to indicate a missing field.
+ * @const {number}
+ */
+jspb.BinaryConstants.INVALID_FIELD_NUMBER = -1;
+
+
+/**
+ * The smallest denormal float32 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT32_EPS = 1.401298464324817e-45;
+
+
+/**
+ * The smallest normal float64 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT32_MIN = 1.1754943508222875e-38;
+
+
+/**
+ * The largest finite float32 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT32_MAX = 3.4028234663852886e+38;
+
+
+/**
+ * The smallest denormal float64 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT64_EPS = 5e-324;
+
+
+/**
+ * The smallest normal float64 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT64_MIN = 2.2250738585072014e-308;
+
+
+/**
+ * The largest finite float64 value.
+ * @const {number}
+ */
+jspb.BinaryConstants.FLOAT64_MAX = 1.7976931348623157e+308;
+
+
+/**
+ * Convenience constant equal to 2^20.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_20 = 1048576;
+
+
+/**
+ * Convenience constant equal to 2^23.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_23 = 8388608;
+
+
+/**
+ * Convenience constant equal to 2^31.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_31 = 2147483648;
+
+
+/**
+ * Convenience constant equal to 2^32.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_32 = 4294967296;
+
+
+/**
+ * Convenience constant equal to 2^52.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_52 = 4503599627370496;
+
+
+/**
+ * Convenience constant equal to 2^63.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_63 = 9223372036854775808;
+
+
+/**
+ * Convenience constant equal to 2^64.
+ * @const {number}
+ */
+jspb.BinaryConstants.TWO_TO_64 = 18446744073709551616;
+
+
+/**
+ * Eight-character string of zeros, used as the default 64-bit hash value.
+ * @const {string}
+ */
+jspb.BinaryConstants.ZERO_HASH = '\0\0\0\0\0\0\0\0';
diff --git a/js/binary/decoder.js b/js/binary/decoder.js
new file mode 100644
index 00000000..9004eff0
--- /dev/null
+++ b/js/binary/decoder.js
@@ -0,0 +1,1005 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains utilities for decoding primitive values
+ * (signed and unsigned integers, varints, booleans, enums, hashes, strings,
+ * and raw bytes) embedded in Uint8Arrays into their corresponding Javascript
+ * types.
+ *
+ * Major caveat - Javascript is unable to accurately represent integers larger
+ * than 2^53 due to its use of a double-precision floating point format or all
+ * numbers. If you need to guarantee that 64-bit values survive with all bits
+ * intact, you _must_ read them using one of the Hash64 methods, which return
+ * an 8-character string.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.BinaryDecoder');
+goog.provide('jspb.BinaryIterator');
+
+goog.require('goog.asserts');
+goog.require('jspb.utils');
+
+
+
+/**
+ * Simple helper class for traversing the contents of repeated scalar fields.
+ * that may or may not have been packed into a wire-format blob.
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @constructor
+ * @struct
+ */
+jspb.BinaryIterator = function(opt_decoder, opt_next, opt_elements) {
+  /** @private {jspb.BinaryDecoder} */
+  this.decoder_ = null;
+
+  /**
+   * The BinaryDecoder member function used when iterating over packed data.
+   * @private {?function(this:jspb.BinaryDecoder):(number|boolean|string)}
+   */
+  this.nextMethod_ = null;
+
+  /** @private {Array.<number>} */
+  this.elements_ = null;
+
+  /** @private {number} */
+  this.cursor_ = 0;
+
+  /** @private {number|boolean|string|null} */
+  this.nextValue_ = null;
+
+  /** @private {boolean} */
+  this.atEnd_ = true;
+
+  this.init_(opt_decoder, opt_next, opt_elements);
+};
+
+
+/**
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @private
+ */
+jspb.BinaryIterator.prototype.init_ =
+    function(opt_decoder, opt_next, opt_elements) {
+  if (opt_decoder && opt_next) {
+    this.decoder_ = opt_decoder;
+    this.nextMethod_ = opt_next;
+  }
+  this.elements_ = opt_elements ? opt_elements : null;
+  this.cursor_ = 0;
+  this.nextValue_ = null;
+  this.atEnd_ = !this.decoder_ && !this.elements_;
+
+  this.next();
+};
+
+
+/**
+ * Global pool of BinaryIterator instances.
+ * @private {!Array.<!jspb.BinaryIterator>}
+ */
+jspb.BinaryIterator.instanceCache_ = [];
+
+
+/**
+ * Allocates a BinaryIterator from the cache, creating a new one if the cache
+ * is empty.
+ * @param {?jspb.BinaryDecoder=} opt_decoder
+ * @param {?function(this:jspb.BinaryDecoder):(number|boolean|string)=}
+ *     opt_next The decoder method to use for next().
+ * @param {?Array.<number|boolean|string>=} opt_elements
+ * @return {!jspb.BinaryIterator}
+ */
+jspb.BinaryIterator.alloc = function(opt_decoder, opt_next, opt_elements) {
+  if (jspb.BinaryIterator.instanceCache_.length) {
+    var iterator = jspb.BinaryIterator.instanceCache_.pop();
+    iterator.init_(opt_decoder, opt_next, opt_elements);
+    return iterator;
+  } else {
+    return new jspb.BinaryIterator(opt_decoder, opt_next, opt_elements);
+  }
+};
+
+
+/**
+ * Puts this instance back in the instance cache.
+ */
+jspb.BinaryIterator.prototype.free = function() {
+  this.clear();
+  if (jspb.BinaryIterator.instanceCache_.length < 100) {
+    jspb.BinaryIterator.instanceCache_.push(this);
+  }
+};
+
+
+/**
+ * Clears the iterator.
+ */
+jspb.BinaryIterator.prototype.clear = function() {
+  if (this.decoder_) {
+    this.decoder_.free();
+  }
+  this.decoder_ = null;
+  this.nextMethod_ = null;
+  this.elements_ = null;
+  this.cursor_ = 0;
+  this.nextValue_ = null;
+  this.atEnd_ = true;
+};
+
+
+/**
+ * Returns the element at the iterator, or null if the iterator is invalid or
+ * past the end of the decoder/array.
+ * @return {number|boolean|string|null}
+ */
+jspb.BinaryIterator.prototype.get = function() {
+  return this.nextValue_;
+};
+
+
+/**
+ * Returns true if the iterator is at the end of the decoder/array.
+ * @return {boolean}
+ */
+jspb.BinaryIterator.prototype.atEnd = function() {
+  return this.atEnd_;
+};
+
+
+/**
+ * Returns the element at the iterator and steps to the next element,
+ * equivalent to '*pointer++' in C.
+ * @return {number|boolean|string|null}
+ */
+jspb.BinaryIterator.prototype.next = function() {
+  var lastValue = this.nextValue_;
+  if (this.decoder_) {
+    if (this.decoder_.atEnd()) {
+      this.nextValue_ = null;
+      this.atEnd_ = true;
+    } else {
+      this.nextValue_ = this.nextMethod_.call(this.decoder_);
+    }
+  } else if (this.elements_) {
+    if (this.cursor_ == this.elements_.length) {
+      this.nextValue_ = null;
+      this.atEnd_ = true;
+    } else {
+      this.nextValue_ = this.elements_[this.cursor_++];
+    }
+  }
+  return lastValue;
+};
+
+
+
+/**
+ * BinaryDecoder implements the decoders for all the wire types specified in
+ * https://developers.google.com/protocol-buffers/docs/encoding.
+ *
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @constructor
+ * @struct
+ */
+jspb.BinaryDecoder = function(opt_bytes, opt_start, opt_length) {
+  /**
+   * Typed byte-wise view of the source buffer.
+   * @private {Uint8Array}
+   */
+  this.bytes_ = null;
+
+  /**
+   * Start point of the block to read.
+   * @private {number}
+   */
+  this.start_ = 0;
+
+  /**
+   * End point of the block to read.
+   * @private {number}
+   */
+  this.end_ = 0;
+
+  /**
+   * Current read location in bytes_.
+   * @private {number}
+   */
+  this.cursor_ = 0;
+
+  /**
+   * Temporary storage for the low 32 bits of 64-bit data types that we're
+   * decoding.
+   * @private {number}
+   */
+  this.tempLow_ = 0;
+
+  /**
+   * Temporary storage for the high 32 bits of 64-bit data types that we're
+   * decoding.
+   * @private {number}
+   */
+  this.tempHigh_ = 0;
+
+  /**
+   * Set to true if this decoder encountered an error due to corrupt data.
+   * @private {boolean}
+   */
+  this.error_ = false;
+
+  if (opt_bytes) {
+    this.setBlock(opt_bytes, opt_start, opt_length);
+  }
+};
+
+
+/**
+ * Global pool of BinaryDecoder instances.
+ * @private {!Array.<!jspb.BinaryDecoder>}
+ */
+jspb.BinaryDecoder.instanceCache_ = [];
+
+
+/**
+ * Pops an instance off the instance cache, or creates one if the cache is
+ * empty.
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @return {!jspb.BinaryDecoder}
+ */
+jspb.BinaryDecoder.alloc = function(opt_bytes, opt_start, opt_length) {
+  if (jspb.BinaryDecoder.instanceCache_.length) {
+    var newDecoder = jspb.BinaryDecoder.instanceCache_.pop();
+    if (opt_bytes) {
+      newDecoder.setBlock(opt_bytes, opt_start, opt_length);
+    }
+    return newDecoder;
+  } else {
+    return new jspb.BinaryDecoder(opt_bytes, opt_start, opt_length);
+  }
+};
+
+
+/**
+ * Puts this instance back in the instance cache.
+ */
+jspb.BinaryDecoder.prototype.free = function() {
+  this.clear();
+  if (jspb.BinaryDecoder.instanceCache_.length < 100) {
+    jspb.BinaryDecoder.instanceCache_.push(this);
+  }
+};
+
+
+/**
+ * Makes a copy of this decoder.
+ * @return {!jspb.BinaryDecoder}
+ */
+jspb.BinaryDecoder.prototype.clone = function() {
+  return jspb.BinaryDecoder.alloc(this.bytes_,
+      this.start_, this.end_ - this.start_);
+};
+
+
+/**
+ * Clears the decoder.
+ */
+jspb.BinaryDecoder.prototype.clear = function() {
+  this.bytes_ = null;
+  this.start_ = 0;
+  this.end_ = 0;
+  this.cursor_ = 0;
+  this.error_ = false;
+};
+
+
+/**
+ * Returns the raw buffer.
+ * @return {Uint8Array} The raw buffer.
+ */
+jspb.BinaryDecoder.prototype.getBuffer = function() {
+  return this.bytes_;
+};
+
+
+/**
+ * Changes the block of bytes we're decoding.
+ * @param {!jspb.ByteSource} data The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ */
+jspb.BinaryDecoder.prototype.setBlock =
+    function(data, opt_start, opt_length) {
+  this.bytes_ = jspb.utils.byteSourceToUint8Array(data);
+  this.start_ = goog.isDef(opt_start) ? opt_start : 0;
+  this.end_ =
+      goog.isDef(opt_length) ? this.start_ + opt_length : this.bytes_.length;
+  this.cursor_ = this.start_;
+};
+
+
+/**
+ * @return {number}
+ */
+jspb.BinaryDecoder.prototype.getEnd = function() {
+  return this.end_;
+};
+
+
+/**
+ * @param {number} end
+ */
+jspb.BinaryDecoder.prototype.setEnd = function(end) {
+  this.end_ = end;
+};
+
+
+/**
+ * Moves the read cursor back to the start of the block.
+ */
+jspb.BinaryDecoder.prototype.reset = function() {
+  this.cursor_ = this.start_;
+};
+
+
+/**
+ * Returns the internal read cursor.
+ * @return {number} The internal read cursor.
+ */
+jspb.BinaryDecoder.prototype.getCursor = function() {
+  return this.cursor_;
+};
+
+
+/**
+ * Returns the internal read cursor.
+ * @param {number} cursor The new cursor.
+ */
+jspb.BinaryDecoder.prototype.setCursor = function(cursor) {
+  this.cursor_ = cursor;
+};
+
+
+/**
+ * Advances the stream cursor by the given number of bytes.
+ * @param {number} count The number of bytes to advance by.
+ */
+jspb.BinaryDecoder.prototype.advance = function(count) {
+  this.cursor_ += count;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+};
+
+
+/**
+ * Returns true if this decoder is at the end of the block.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.atEnd = function() {
+  return this.cursor_ == this.end_;
+};
+
+
+/**
+ * Returns true if this decoder is at the end of the block.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.pastEnd = function() {
+  return this.cursor_ > this.end_;
+};
+
+
+/**
+ * Returns true if this decoder encountered an error due to corrupt data.
+ * @return {boolean}
+ */
+jspb.BinaryDecoder.prototype.getError = function() {
+  return this.error_ ||
+         (this.cursor_ < 0) ||
+         (this.cursor_ > this.end_);
+};
+
+
+/**
+ * Reads an unsigned varint from the binary stream and stores it as a split
+ * 64-bit integer. Since this does not convert the value to a number, no
+ * precision is lost.
+ *
+ * It's possible for an unsigned varint to be incorrectly encoded - more than
+ * 64 bits' worth of data could be present. If this happens, this method will
+ * throw an error.
+ *
+ * Decoding varints requires doing some funny base-128 math - for more
+ * details on the format, see
+ * https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @private
+ */
+jspb.BinaryDecoder.prototype.readSplitVarint64_ = function() {
+  var temp;
+  var lowBits = 0;
+  var highBits = 0;
+
+  // Read the first four bytes of the varint, stopping at the terminator if we
+  // see it.
+  for (var i = 0; i < 4; i++) {
+    temp = this.bytes_[this.cursor_++];
+    lowBits |= (temp & 0x7F) << (i * 7);
+    if (temp < 128) {
+      this.tempLow_ = lowBits >>> 0;
+      this.tempHigh_ = 0;
+      return;
+    }
+  }
+
+  // Read the fifth byte, which straddles the low and high dwords.
+  temp = this.bytes_[this.cursor_++];
+  lowBits |= (temp & 0x7F) << 28;
+  highBits |= (temp & 0x7F) >> 4;
+  if (temp < 128) {
+    this.tempLow_ = lowBits >>> 0;
+    this.tempHigh_ = highBits >>> 0;
+    return;
+  }
+
+  // Read the sixth through tenth byte.
+  for (var i = 0; i < 5; i++) {
+    temp = this.bytes_[this.cursor_++];
+    highBits |= (temp & 0x7F) << (i * 7 + 3);
+    if (temp < 128) {
+      this.tempLow_ = lowBits >>> 0;
+      this.tempHigh_ = highBits >>> 0;
+      return;
+    }
+  }
+
+  // If we did not see the terminator, the encoding was invalid.
+  goog.asserts.fail('Failed to read varint, encoding is invalid.');
+  this.error_ = true;
+};
+
+
+/**
+ * Skips over a varint in the block without decoding it.
+ */
+jspb.BinaryDecoder.prototype.skipVarint = function() {
+  while (this.bytes_[this.cursor_] & 0x80) {
+    this.cursor_++;
+  }
+  this.cursor_++;
+};
+
+
+/**
+ * Skips backwards over a varint in the block - to do this correctly, we have
+ * to know the value we're skipping backwards over or things are ambiguous.
+ * @param {number} value The varint value to unskip.
+ */
+jspb.BinaryDecoder.prototype.unskipVarint = function(value) {
+  while (value > 128) {
+    this.cursor_--;
+    value = value >>> 7;
+  }
+  this.cursor_--;
+};
+
+
+/**
+ * Reads a 32-bit varint from the binary stream. Due to a quirk of the encoding
+ * format and Javascript's handling of bitwise math, this actually works
+ * correctly for both signed and unsigned 32-bit varints.
+ *
+ * This function is called vastly more frequently than any other in
+ * BinaryDecoder, so it has been unrolled and tweaked for performance.
+ *
+ * If there are more than 32 bits of data in the varint, it _must_ be due to
+ * sign-extension. If we're in debug mode and the high 32 bits don't match the
+ * expected sign extension, this method will throw an error.
+ *
+ * Decoding varints requires doing some funny base-128 math - for more
+ * details on the format, see
+ * https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded unsigned 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint32 = function() {
+  var temp;
+  var bytes = this.bytes_;
+
+  temp = bytes[this.cursor_ + 0];
+  var x = (temp & 0x7F);
+  if (temp < 128) {
+    this.cursor_ += 1;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 1];
+  x |= (temp & 0x7F) << 7;
+  if (temp < 128) {
+    this.cursor_ += 2;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 2];
+  x |= (temp & 0x7F) << 14;
+  if (temp < 128) {
+    this.cursor_ += 3;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 3];
+  x |= (temp & 0x7F) << 21;
+  if (temp < 128) {
+    this.cursor_ += 4;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x;
+  }
+
+  temp = bytes[this.cursor_ + 4];
+  x |= (temp & 0x0F) << 28;
+  if (temp < 128) {
+    // We're reading the high bits of an unsigned varint. The byte we just read
+    // also contains bits 33 through 35, which we're going to discard. Those
+    // bits _must_ be zero, or the encoding is invalid.
+    goog.asserts.assert((temp & 0xF0) == 0);
+    this.cursor_ += 5;
+    goog.asserts.assert(this.cursor_ <= this.end_);
+    return x >>> 0;
+  }
+
+  // If we get here, we're reading the sign extension of a negative 32-bit int.
+  // We can skip these bytes, as we know in advance that they have to be all
+  // 1's if the varint is correctly encoded. Since we also know the value is
+  // negative, we don't have to coerce it to unsigned before we return it.
+
+  goog.asserts.assert((temp & 0xF0) == 0xF0);
+  goog.asserts.assert(bytes[this.cursor_ + 5] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 6] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 7] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 8] == 0xFF);
+  goog.asserts.assert(bytes[this.cursor_ + 9] == 0x01);
+
+  this.cursor_ += 10;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return x;
+};
+
+
+/**
+ * The readUnsignedVarint32 above deals with signed 32-bit varints correctly,
+ * so this is just an alias.
+ *
+ * @return {number} The decoded signed 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint32 =
+    jspb.BinaryDecoder.prototype.readUnsignedVarint32;
+
+
+/**
+ * Reads a 32-bit unsigned variant and returns its value as a string.
+ *
+ * @return {string} The decoded unsigned 32-bit varint as a string.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint32String = function() {
+  // 32-bit integers fit in JavaScript numbers without loss of precision, so
+  // string variants of 32-bit varint readers can simply delegate then convert
+  // to string.
+  var value = this.readUnsignedVarint32();
+  return value.toString();
+};
+
+/**
+ * Reads a 32-bit signed variant and returns its value as a string.
+ *
+ * @return {string} The decoded signed 32-bit varint as a string.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint32String = function() {
+  // 32-bit integers fit in JavaScript numbers without loss of precision, so
+  // string variants of 32-bit varint readers can simply delegate then convert
+  // to string.
+  var value = this.readSignedVarint32();
+  return value.toString();
+};
+
+
+/**
+ * Reads a signed, zigzag-encoded 32-bit varint from the binary stream.
+ *
+ * Zigzag encoding is a modification of varint encoding that reduces the
+ * storage overhead for small negative integers - for more details on the
+ * format, see https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded signed, zigzag-encoded 32-bit varint.
+ */
+jspb.BinaryDecoder.prototype.readZigzagVarint32 = function() {
+  var result = this.readUnsignedVarint32();
+  return (result >>> 1) ^ - (result & 1);
+};
+
+
+/**
+ * Reads an unsigned 64-bit varint from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the varint is larger than 2^53.
+ *
+ * @return {number} The decoded unsigned varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinUint64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads an unsigned 64-bit varint from the binary stream and returns the value
+ * as a decimal string.
+ *
+ * @return {string} The decoded unsigned varint as a decimal string.
+ */
+jspb.BinaryDecoder.prototype.readUnsignedVarint64String = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinUnsignedDecimalString(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a signed 64-bit varint from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the varint is larger than 2^53.
+ *
+ * @return {number} The decoded signed varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinInt64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads an signed 64-bit varint from the binary stream and returns the value
+ * as a decimal string.
+ *
+ * @return {string} The decoded signed varint as a decimal string.
+ */
+jspb.BinaryDecoder.prototype.readSignedVarint64String = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinSignedDecimalString(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a signed, zigzag-encoded 64-bit varint from the binary stream. Note
+ * that since Javascript represents all numbers as double-precision floats,
+ * there will be precision lost if the absolute value of the varint is larger
+ * than 2^53.
+ *
+ * Zigzag encoding is a modification of varint encoding that reduces the
+ * storage overhead for small negative integers - for more details on the
+ * format, see https://developers.google.com/protocol-buffers/docs/encoding
+ *
+ * @return {number} The decoded zigzag varint. Precision will be lost if the
+ *     integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readZigzagVarint64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinZigzag64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a raw unsigned 8-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 8-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint8 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  this.cursor_ += 1;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return a;
+};
+
+
+/**
+ * Reads a raw unsigned 16-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 16-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint16 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  this.cursor_ += 2;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 0) | (b << 8);
+};
+
+
+/**
+ * Reads a raw unsigned 32-bit integer from the binary stream.
+ *
+ * @return {number} The unsigned 32-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readUint32 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  var c = this.bytes_[this.cursor_ + 2];
+  var d = this.bytes_[this.cursor_ + 3];
+  this.cursor_ += 4;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return ((a << 0) | (b << 8) | (c << 16) | (d << 24)) >>> 0;
+};
+
+
+/**
+ * Reads a raw unsigned 64-bit integer from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute value of the integer is larger than 2^53.
+ *
+ * @return {number} The unsigned 64-bit integer read from the binary stream.
+ *     Precision will be lost if the integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readUint64 = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinUint64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a raw signed 8-bit integer from the binary stream.
+ *
+ * @return {number} The signed 8-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt8 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  this.cursor_ += 1;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 24) >> 24;
+};
+
+
+/**
+ * Reads a raw signed 16-bit integer from the binary stream.
+ *
+ * @return {number} The signed 16-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt16 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  this.cursor_ += 2;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (((a << 0) | (b << 8)) << 16) >> 16;
+};
+
+
+/**
+ * Reads a raw signed 32-bit integer from the binary stream.
+ *
+ * @return {number} The signed 32-bit integer read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readInt32 = function() {
+  var a = this.bytes_[this.cursor_ + 0];
+  var b = this.bytes_[this.cursor_ + 1];
+  var c = this.bytes_[this.cursor_ + 2];
+  var d = this.bytes_[this.cursor_ + 3];
+  this.cursor_ += 4;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return (a << 0) | (b << 8) | (c << 16) | (d << 24);
+};
+
+
+/**
+ * Reads a raw signed 64-bit integer from the binary stream. Note that since
+ * Javascript represents all numbers as double-precision floats, there will be
+ * precision lost if the absolute vlaue of the integer is larger than 2^53.
+ *
+ * @return {number} The signed 64-bit integer read from the binary stream.
+ *     Precision will be lost if the integer exceeds 2^53.
+ */
+jspb.BinaryDecoder.prototype.readInt64 = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinInt64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a 32-bit floating-point number from the binary stream, using the
+ * temporary buffer to realign the data.
+ *
+ * @return {number} The float read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readFloat = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = 0;
+  return jspb.utils.joinFloat32(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a 64-bit floating-point number from the binary stream, using the
+ * temporary buffer to realign the data.
+ *
+ * @return {number} The double read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readDouble = function() {
+  var bitsLow = this.readUint32();
+  var bitsHigh = this.readUint32();
+  return jspb.utils.joinFloat64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Reads a boolean value from the binary stream.
+ * @return {boolean} The boolean read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readBool = function() {
+  return !!this.bytes_[this.cursor_++];
+};
+
+
+/**
+ * Reads an enum value from the binary stream, which are always encoded as
+ * signed varints.
+ * @return {number} The enum value read from the binary stream.
+ */
+jspb.BinaryDecoder.prototype.readEnum = function() {
+  return this.readSignedVarint32();
+};
+
+
+/**
+ * Reads and parses a UTF-8 encoded unicode string from the stream.
+ * The code is inspired by maps.vectortown.parse.StreamedDataViewReader, with
+ * the exception that the implementation here does not get confused if it
+ * encounters characters longer than three bytes. These characters are ignored
+ * though, as they are extremely rare: three UTF-8 bytes cover virtually all
+ * characters in common use (http://en.wikipedia.org/wiki/UTF-8).
+ * @param {number} length The length of the string to read.
+ * @return {string} The decoded string.
+ */
+jspb.BinaryDecoder.prototype.readString = function(length) {
+  var bytes = this.bytes_;
+  var cursor = this.cursor_;
+  var end = cursor + length;
+  var chars = [];
+
+  while (cursor < end) {
+    var c = bytes[cursor++];
+    if (c < 128) { // Regular 7-bit ASCII.
+      chars.push(c);
+    } else if (c < 192) {
+      // UTF-8 continuation mark. We are out of sync. This
+      // might happen if we attempted to read a character
+      // with more than three bytes.
+      continue;
+    } else if (c < 224) { // UTF-8 with two bytes.
+      var c2 = bytes[cursor++];
+      chars.push(((c & 31) << 6) | (c2 & 63));
+    } else if (c < 240) { // UTF-8 with three bytes.
+      var c2 = bytes[cursor++];
+      var c3 = bytes[cursor++];
+      chars.push(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
+    }
+  }
+
+  // String.fromCharCode.apply is faster than manually appending characters on
+  // Chrome 25+, and generates no additional cons string garbage.
+  var result = String.fromCharCode.apply(null, chars);
+  this.cursor_ = cursor;
+  return result;
+};
+
+
+/**
+ * Reads and parses a UTF-8 encoded unicode string (with length prefix) from
+ * the stream.
+ * @return {string} The decoded string.
+ */
+jspb.BinaryDecoder.prototype.readStringWithLength = function() {
+  var length = this.readUnsignedVarint32();
+  return this.readString(length);
+};
+
+
+/**
+ * Reads a block of raw bytes from the binary stream.
+ *
+ * @param {number} length The number of bytes to read.
+ * @return {Uint8Array} The decoded block of bytes, or null if the length was
+ *     invalid.
+ */
+jspb.BinaryDecoder.prototype.readBytes = function(length) {
+  if (length < 0 ||
+      this.cursor_ + length > this.bytes_.length) {
+    this.error_ = true;
+    return null;
+  }
+
+  var result = this.bytes_.subarray(this.cursor_, this.cursor_ + length);
+
+  this.cursor_ += length;
+  goog.asserts.assert(this.cursor_ <= this.end_);
+  return result;
+};
+
+
+/**
+ * Reads a 64-bit varint from the stream and returns it as an 8-character
+ * Unicode string for use as a hash table key.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryDecoder.prototype.readVarintHash64 = function() {
+  this.readSplitVarint64_();
+  return jspb.utils.joinHash64(this.tempLow_, this.tempHigh_);
+};
+
+
+/**
+ * Reads a 64-bit fixed-width value from the stream and returns it as an
+ * 8-character Unicode string for use as a hash table key.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryDecoder.prototype.readFixedHash64 = function() {
+  var bytes = this.bytes_;
+  var cursor = this.cursor_;
+
+  var a = bytes[cursor + 0];
+  var b = bytes[cursor + 1];
+  var c = bytes[cursor + 2];
+  var d = bytes[cursor + 3];
+  var e = bytes[cursor + 4];
+  var f = bytes[cursor + 5];
+  var g = bytes[cursor + 6];
+  var h = bytes[cursor + 7];
+
+  this.cursor_ += 8;
+
+  return String.fromCharCode(a, b, c, d, e, f, g, h);
+};
diff --git a/js/binary/decoder_test.js b/js/binary/decoder_test.js
new file mode 100644
index 00000000..27342e49
--- /dev/null
+++ b/js/binary/decoder_test.js
@@ -0,0 +1,327 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Test cases for jspb's binary protocol buffer decoder.
+ *
+ * There are two particular magic numbers that need to be pointed out -
+ * 2^64-1025 is the largest number representable as both a double and an
+ * unsigned 64-bit integer, and 2^63-513 is the largest number representable as
+ * both a double and a signed 64-bit integer.
+ *
+ * Test suite is written using Jasmine -- see http://jasmine.github.io/
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.require('goog.testing.asserts');
+goog.require('jspb.BinaryConstants');
+goog.require('jspb.BinaryDecoder');
+goog.require('jspb.BinaryWriter');
+
+
+/**
+ * Tests raw encoding and decoding of unsigned types.
+ * @param {Function} readValue
+ * @param {Function} writeValue
+ * @param {number} epsilon
+ * @param {number} upperLimit
+ * @param {Function} filter
+ * @suppress {missingProperties|visibility}
+ */
+function doTestUnsignedValue(readValue,
+    writeValue, epsilon, upperLimit, filter) {
+  var writer = new jspb.BinaryWriter();
+
+  // Encode zero and limits.
+  writeValue.call(writer, filter(0));
+  writeValue.call(writer, filter(epsilon));
+  writeValue.call(writer, filter(upperLimit));
+
+  // Encode positive values.
+  for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+    writeValue.call(writer, filter(cursor));
+  }
+
+  var reader = jspb.BinaryDecoder.alloc(writer.getResultBuffer());
+
+  // Check zero and limits.
+  assertEquals(filter(0), readValue.call(reader));
+  assertEquals(filter(epsilon), readValue.call(reader));
+  assertEquals(filter(upperLimit), readValue.call(reader));
+
+  // Check positive values.
+  for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+    if (filter(cursor) != readValue.call(reader)) throw 'fail!';
+  }
+}
+
+
+/**
+ * Tests raw encoding and decoding of signed types.
+ * @param {Function} readValue
+ * @param {Function} writeValue
+ * @param {number} epsilon
+ * @param {number} lowerLimit
+ * @param {number} upperLimit
+ * @param {Function} filter
+ * @suppress {missingProperties}
+ */
+function doTestSignedValue(readValue,
+    writeValue, epsilon, lowerLimit, upperLimit, filter) {
+  var writer = new jspb.BinaryWriter();
+
+  // Encode zero and limits.
+  writeValue.call(writer, filter(lowerLimit));
+  writeValue.call(writer, filter(-epsilon));
+  writeValue.call(writer, filter(0));
+  writeValue.call(writer, filter(epsilon));
+  writeValue.call(writer, filter(upperLimit));
+
+  var inputValues = [];
+
+  // Encode negative values.
+  for (var cursor = lowerLimit; cursor < -epsilon; cursor /= 1.1) {
+    var val = filter(cursor);
+    writeValue.call(writer, val);
+    inputValues.push(val);
+  }
+
+  // Encode positive values.
+  for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+    var val = filter(cursor);
+    writeValue.call(writer, val);
+    inputValues.push(val);
+  }
+
+  var reader = jspb.BinaryDecoder.alloc(writer.getResultBuffer());
+
+  // Check zero and limits.
+  assertEquals(filter(lowerLimit), readValue.call(reader));
+  assertEquals(filter(-epsilon), readValue.call(reader));
+  assertEquals(filter(0), readValue.call(reader));
+  assertEquals(filter(epsilon), readValue.call(reader));
+  assertEquals(filter(upperLimit), readValue.call(reader));
+
+  // Verify decoded values.
+  for (var i = 0; i < inputValues.length; i++) {
+    assertEquals(inputValues[i], readValue.call(reader));
+  }
+}
+
+describe('binaryDecoderTest', function() {
+  /**
+   * Tests the decoder instance cache.
+   * @suppress {visibility}
+   */
+  it('testInstanceCache', function() {
+    // Empty the instance caches.
+    jspb.BinaryDecoder.instanceCache_ = [];
+
+    // Allocating and then freeing a decoder should put it in the instance
+    // cache.
+    jspb.BinaryDecoder.alloc().free();
+
+    assertEquals(1, jspb.BinaryDecoder.instanceCache_.length);
+
+    // Allocating and then freeing three decoders should leave us with three in
+    // the cache.
+
+    var decoder1 = jspb.BinaryDecoder.alloc();
+    var decoder2 = jspb.BinaryDecoder.alloc();
+    var decoder3 = jspb.BinaryDecoder.alloc();
+    decoder1.free();
+    decoder2.free();
+    decoder3.free();
+
+    assertEquals(3, jspb.BinaryDecoder.instanceCache_.length);
+  });
+
+
+  /**
+   * Tests reading 64-bit integers as hash strings.
+   */
+  it('testHashStrings', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var hashA = String.fromCharCode(0x00, 0x00, 0x00, 0x00,
+                                    0x00, 0x00, 0x00, 0x00);
+    var hashB = String.fromCharCode(0x12, 0x34, 0x00, 0x00,
+                                    0x00, 0x00, 0x00, 0x00);
+    var hashC = String.fromCharCode(0x12, 0x34, 0x56, 0x78,
+                                    0x87, 0x65, 0x43, 0x21);
+    var hashD = String.fromCharCode(0xFF, 0xFF, 0xFF, 0xFF,
+                                    0xFF, 0xFF, 0xFF, 0xFF);
+
+    writer.rawWriteVarintHash64(hashA);
+    writer.rawWriteVarintHash64(hashB);
+    writer.rawWriteVarintHash64(hashC);
+    writer.rawWriteVarintHash64(hashD);
+
+    writer.rawWriteFixedHash64(hashA);
+    writer.rawWriteFixedHash64(hashB);
+    writer.rawWriteFixedHash64(hashC);
+    writer.rawWriteFixedHash64(hashD);
+
+    var decoder = jspb.BinaryDecoder.alloc(writer.getResultBuffer());
+
+    assertEquals(hashA, decoder.readVarintHash64());
+    assertEquals(hashB, decoder.readVarintHash64());
+    assertEquals(hashC, decoder.readVarintHash64());
+    assertEquals(hashD, decoder.readVarintHash64());
+
+    assertEquals(hashA, decoder.readFixedHash64());
+    assertEquals(hashB, decoder.readFixedHash64());
+    assertEquals(hashC, decoder.readFixedHash64());
+    assertEquals(hashD, decoder.readFixedHash64());
+  });
+
+
+  /**
+   * Verifies that misuse of the decoder class triggers assertions.
+   * @suppress {checkTypes|visibility}
+   */
+  it('testDecodeErrors', function() {
+    // Reading a value past the end of the stream should trigger an assertion.
+    var decoder = jspb.BinaryDecoder.alloc([0, 1, 2]);
+    assertThrows(function() {decoder.readUint64()});
+
+    // Overlong varints should trigger assertions.
+    decoder.setBlock(
+        [255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 0]);
+    assertThrows(function() {decoder.readUnsignedVarint64()});
+    decoder.reset();
+    assertThrows(function() {decoder.readSignedVarint64()});
+    decoder.reset();
+    assertThrows(function() {decoder.readZigzagVarint64()});
+
+    // Positive 32-bit varints encoded with 1 bits in positions 33 through 35
+    // should trigger assertions.
+    decoder.setBlock([255, 255, 255, 255, 0x1F]);
+    assertThrows(function() {decoder.readUnsignedVarint32()});
+
+    decoder.setBlock([255, 255, 255, 255, 0x2F]);
+    assertThrows(function() {decoder.readUnsignedVarint32()});
+
+    decoder.setBlock([255, 255, 255, 255, 0x4F]);
+    assertThrows(function() {decoder.readUnsignedVarint32()});
+
+    // Negative 32-bit varints encoded with non-1 bits in the high dword should
+    // trigger assertions.
+    decoder.setBlock([255, 255, 255, 255, 255, 255, 0, 255, 255, 1]);
+    assertThrows(function() {decoder.readUnsignedVarint32()});
+
+    decoder.setBlock([255, 255, 255, 255, 255, 255, 255, 255, 255, 0]);
+    assertThrows(function() {decoder.readUnsignedVarint32()});
+  });
+
+
+  /**
+   * Tests raw encoding and decoding of unsigned integers.
+   */
+  it('testRawUnsigned', function() {
+    doTestUnsignedValue(
+        jspb.BinaryDecoder.prototype.readUint8,
+        jspb.BinaryWriter.prototype.rawWriteUint8,
+        1, 0xFF, Math.round);
+
+    doTestUnsignedValue(
+        jspb.BinaryDecoder.prototype.readUint16,
+        jspb.BinaryWriter.prototype.rawWriteUint16,
+        1, 0xFFFF, Math.round);
+
+    doTestUnsignedValue(
+        jspb.BinaryDecoder.prototype.readUint32,
+        jspb.BinaryWriter.prototype.rawWriteUint32,
+        1, 0xFFFFFFFF, Math.round);
+
+    doTestUnsignedValue(
+        jspb.BinaryDecoder.prototype.readUint64,
+        jspb.BinaryWriter.prototype.rawWriteUint64,
+        1, Math.pow(2, 64) - 1025, Math.round);
+  });
+
+
+  /**
+   * Tests raw encoding and decoding of signed integers.
+   */
+  it('testRawSigned', function() {
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readInt8,
+        jspb.BinaryWriter.prototype.rawWriteInt8,
+        1, -0x80, 0x7F, Math.round);
+
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readInt16,
+        jspb.BinaryWriter.prototype.rawWriteInt16,
+        1, -0x8000, 0x7FFF, Math.round);
+
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readInt32,
+        jspb.BinaryWriter.prototype.rawWriteInt32,
+        1, -0x80000000, 0x7FFFFFFF, Math.round);
+
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readInt64,
+        jspb.BinaryWriter.prototype.rawWriteInt64,
+        1, -Math.pow(2, 63), Math.pow(2, 63) - 513, Math.round);
+  });
+
+
+  /**
+   * Tests raw encoding and decoding of floats.
+   */
+  it('testRawFloats', function() {
+    /**
+     * @param {number} x
+     * @return {number}
+     */
+    function truncate(x) {
+      var temp = new Float32Array(1);
+      temp[0] = x;
+      return temp[0];
+    }
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readFloat,
+        jspb.BinaryWriter.prototype.rawWriteFloat,
+        jspb.BinaryConstants.FLOAT32_EPS,
+        -jspb.BinaryConstants.FLOAT32_MAX,
+        jspb.BinaryConstants.FLOAT32_MAX,
+        truncate);
+
+    doTestSignedValue(
+        jspb.BinaryDecoder.prototype.readDouble,
+        jspb.BinaryWriter.prototype.rawWriteDouble,
+        jspb.BinaryConstants.FLOAT64_EPS * 10,
+        -jspb.BinaryConstants.FLOAT64_MAX,
+        jspb.BinaryConstants.FLOAT64_MAX,
+        function(x) { return x; });
+  });
+});
diff --git a/js/binary/proto_test.js b/js/binary/proto_test.js
new file mode 100644
index 00000000..32d8412f
--- /dev/null
+++ b/js/binary/proto_test.js
@@ -0,0 +1,588 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test suite is written using Jasmine -- see http://jasmine.github.io/
+
+goog.require('goog.testing.asserts');
+goog.require('proto.jspb.test.ExtendsWithMessage');
+goog.require('proto.jspb.test.ForeignEnum');
+goog.require('proto.jspb.test.ForeignMessage');
+goog.require('proto.jspb.test.TestAllTypes');
+goog.require('proto.jspb.test.TestExtendable');
+
+var suite = {};
+
+/**
+ * Helper: fill all fields on a TestAllTypes message.
+ * @param {proto.jspb.test.TestAllTypes} msg
+ */
+function fillAllFields(msg) {
+  msg.setOptionalInt32(-42);
+  // can be exactly represented by JS number (64-bit double, i.e., 52-bit
+  // mantissa).
+  msg.setOptionalInt64(-0x7fffffff00000000);
+  msg.setOptionalUint32(0x80000000);
+  msg.setOptionalUint64(0xf000000000000000);
+  msg.setOptionalSint32(-100);
+  msg.setOptionalSint64(-0x8000000000000000);
+  msg.setOptionalFixed32(1234);
+  msg.setOptionalFixed64(0x1234567800000000);
+  msg.setOptionalSfixed32(-1234);
+  msg.setOptionalSfixed64(-0x1234567800000000);
+  msg.setOptionalFloat(1.5);
+  msg.setOptionalDouble(-1.5);
+  msg.setOptionalBool(true);
+  msg.setOptionalString('hello world');
+  msg.setOptionalBytes('bytes');
+  msg.setOptionalGroup(new proto.jspb.test.TestAllTypes.OptionalGroup());
+  msg.getOptionalGroup().setA(100);
+  var submsg = new proto.jspb.test.ForeignMessage();
+  submsg.setC(16);
+  msg.setOptionalForeignMessage(submsg);
+  msg.setOptionalForeignEnum(proto.jspb.test.ForeignEnum.FOREIGN_FOO);
+  msg.setOptionalInt32String('-12345');
+  msg.setOptionalUint32String('12345');
+  msg.setOptionalInt64String('-123456789012345');
+  msg.setOptionalUint64String('987654321098765');
+  msg.setOneofString('oneof');
+
+  msg.setRepeatedInt32List([-42]);
+  msg.setRepeatedInt64List([-0x7fffffff00000000]);
+  msg.setRepeatedUint32List([0x80000000]);
+  msg.setRepeatedUint64List([0xf000000000000000]);
+  msg.setRepeatedSint32List([-100]);
+  msg.setRepeatedSint64List([-0x8000000000000000]);
+  msg.setRepeatedFixed32List([1234]);
+  msg.setRepeatedFixed64List([0x1234567800000000]);
+  msg.setRepeatedSfixed32List([-1234]);
+  msg.setRepeatedSfixed64List([-0x1234567800000000]);
+  msg.setRepeatedFloatList([1.5]);
+  msg.setRepeatedDoubleList([-1.5]);
+  msg.setRepeatedBoolList([true]);
+  msg.setRepeatedStringList(['hello world']);
+  msg.setRepeatedBytesList(['bytes']);
+  msg.setRepeatedGroupList([new proto.jspb.test.TestAllTypes.RepeatedGroup()]);
+  msg.getRepeatedGroupList()[0].setA(100);
+  submsg = new proto.jspb.test.ForeignMessage();
+  submsg.setC(1000);
+  msg.setRepeatedForeignMessageList([submsg]);
+  msg.setRepeatedForeignEnumList([proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+  msg.setPackedRepeatedInt32List([-42]);
+  msg.setPackedRepeatedInt64List([-0x7fffffff00000000]);
+  msg.setPackedRepeatedUint32List([0x80000000]);
+  msg.setPackedRepeatedUint64List([0xf000000000000000]);
+  msg.setPackedRepeatedSint32List([-100]);
+  msg.setPackedRepeatedSint64List([-0x8000000000000000]);
+  msg.setPackedRepeatedFixed32List([1234]);
+  msg.setPackedRepeatedFixed64List([0x1234567800000000]);
+  msg.setPackedRepeatedSfixed32List([-1234]);
+  msg.setPackedRepeatedSfixed64List([-0x1234567800000000]);
+  msg.setPackedRepeatedFloatList([1.5]);
+  msg.setPackedRepeatedDoubleList([-1.5]);
+  msg.setPackedRepeatedBoolList([true]);
+
+  msg.setRepeatedInt32StringList(['-12345']);
+  msg.setRepeatedUint32StringList(['12345']);
+  msg.setRepeatedInt64StringList(['-123456789012345']);
+  msg.setRepeatedUint64StringList(['987654321098765']);
+  msg.setPackedRepeatedInt32StringList(['-12345']);
+  msg.setPackedRepeatedUint32StringList(['12345']);
+  msg.setPackedRepeatedInt64StringList(['-123456789012345']);
+  msg.setPackedRepeatedUint64StringList(['987654321098765']);
+}
+
+
+/**
+ * Helper: compare a bytes field to a string with codepoints 0--255.
+ * @param {Uint8Array|string} arr
+ * @param {string} str
+ * @return {boolean}
+ */
+function bytesCompare(arr, str) {
+  if (arr.length != str.length) {
+    return false;
+  }
+  if (typeof arr == 'string') {
+    for (var i = 0; i < arr.length; i++) {
+      if (arr.charCodeAt(i) != str.charCodeAt(i)) {
+        return false;
+      }
+    }
+    return true;
+  } else {
+    for (var i = 0; i < arr.length; i++) {
+      if (arr[i] != str.charCodeAt(i)) {
+        return false;
+      }
+    }
+    return true;
+  }
+}
+
+
+/**
+ * Helper: verify contents of given TestAllTypes message as set by
+ * fillAllFields().
+ * @param {proto.jspb.test.TestAllTypes} msg
+ */
+function checkAllFields(msg) {
+  assertEquals(msg.getOptionalInt32(), -42);
+  assertEquals(msg.getOptionalInt64(), -0x7fffffff00000000);
+  assertEquals(msg.getOptionalUint32(), 0x80000000);
+  assertEquals(msg.getOptionalUint64(), 0xf000000000000000);
+  assertEquals(msg.getOptionalSint32(), -100);
+  assertEquals(msg.getOptionalSint64(), -0x8000000000000000);
+  assertEquals(msg.getOptionalFixed32(), 1234);
+  assertEquals(msg.getOptionalFixed64(), 0x1234567800000000);
+  assertEquals(msg.getOptionalSfixed32(), -1234);
+  assertEquals(msg.getOptionalSfixed64(), -0x1234567800000000);
+  assertEquals(msg.getOptionalFloat(), 1.5);
+  assertEquals(msg.getOptionalDouble(), -1.5);
+  assertEquals(msg.getOptionalBool(), true);
+  assertEquals(msg.getOptionalString(), 'hello world');
+  assertEquals(true, bytesCompare(msg.getOptionalBytes(), 'bytes'));
+  assertEquals(msg.getOptionalGroup().getA(), 100);
+  assertEquals(msg.getOptionalForeignMessage().getC(), 16);
+  assertEquals(msg.getOptionalForeignEnum(),
+      proto.jspb.test.ForeignEnum.FOREIGN_FOO);
+  assertEquals(msg.getOptionalInt32String(), '-12345');
+  assertEquals(msg.getOptionalUint32String(), '12345');
+  assertEquals(msg.getOptionalInt64String(), '-123456789012345');
+  assertEquals(msg.getOptionalUint64String(), '987654321098765');
+  assertEquals(msg.getOneofString(), 'oneof');
+  assertEquals(msg.getOneofFieldCase(),
+      proto.jspb.test.TestAllTypes.OneofFieldCase.ONEOF_STRING);
+
+  assertElementsEquals(msg.getRepeatedInt32List(), [-42]);
+  assertElementsEquals(msg.getRepeatedInt64List(), [-0x7fffffff00000000]);
+  assertElementsEquals(msg.getRepeatedUint32List(), [0x80000000]);
+  assertElementsEquals(msg.getRepeatedUint64List(), [0xf000000000000000]);
+  assertElementsEquals(msg.getRepeatedSint32List(), [-100]);
+  assertElementsEquals(msg.getRepeatedSint64List(), [-0x8000000000000000]);
+  assertElementsEquals(msg.getRepeatedFixed32List(), [1234]);
+  assertElementsEquals(msg.getRepeatedFixed64List(), [0x1234567800000000]);
+  assertElementsEquals(msg.getRepeatedSfixed32List(), [-1234]);
+  assertElementsEquals(msg.getRepeatedSfixed64List(), [-0x1234567800000000]);
+  assertElementsEquals(msg.getRepeatedFloatList(), [1.5]);
+  assertElementsEquals(msg.getRepeatedDoubleList(), [-1.5]);
+  assertElementsEquals(msg.getRepeatedBoolList(), [true]);
+  assertElementsEquals(msg.getRepeatedStringList(), ['hello world']);
+  assertEquals(msg.getRepeatedBytesList().length, 1);
+  assertEquals(true, bytesCompare(msg.getRepeatedBytesList()[0], 'bytes'));
+  assertEquals(msg.getRepeatedGroupList().length, 1);
+  assertEquals(msg.getRepeatedGroupList()[0].getA(), 100);
+  assertEquals(msg.getRepeatedForeignMessageList().length, 1);
+  assertEquals(msg.getRepeatedForeignMessageList()[0].getC(), 1000);
+  assertElementsEquals(msg.getRepeatedForeignEnumList(),
+      [proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+  assertElementsEquals(msg.getPackedRepeatedInt32List(), [-42]);
+  assertElementsEquals(msg.getPackedRepeatedInt64List(),
+      [-0x7fffffff00000000]);
+  assertElementsEquals(msg.getPackedRepeatedUint32List(), [0x80000000]);
+  assertElementsEquals(msg.getPackedRepeatedUint64List(), [0xf000000000000000]);
+  assertElementsEquals(msg.getPackedRepeatedSint32List(), [-100]);
+  assertElementsEquals(msg.getPackedRepeatedSint64List(),
+      [-0x8000000000000000]);
+  assertElementsEquals(msg.getPackedRepeatedFixed32List(), [1234]);
+  assertElementsEquals(msg.getPackedRepeatedFixed64List(),
+      [0x1234567800000000]);
+  assertElementsEquals(msg.getPackedRepeatedSfixed32List(), [-1234]);
+  assertElementsEquals(msg.getPackedRepeatedSfixed64List(),
+      [-0x1234567800000000]);
+  assertElementsEquals(msg.getPackedRepeatedFloatList(), [1.5]);
+  assertElementsEquals(msg.getPackedRepeatedDoubleList(), [-1.5]);
+  assertElementsEquals(msg.getPackedRepeatedBoolList(), [true]);
+
+  assertEquals(msg.getRepeatedInt32StringList().length, 1);
+  assertElementsEquals(msg.getRepeatedInt32StringList(), ['-12345']);
+  assertEquals(msg.getRepeatedUint32StringList().length, 1);
+  assertElementsEquals(msg.getRepeatedUint32StringList(), ['12345']);
+  assertEquals(msg.getRepeatedInt64StringList().length, 1);
+  assertElementsEquals(msg.getRepeatedInt64StringList(), ['-123456789012345']);
+  assertEquals(msg.getRepeatedUint64StringList().length, 1);
+  assertElementsEquals(msg.getRepeatedUint64StringList(), ['987654321098765']);
+
+  assertEquals(msg.getPackedRepeatedInt32StringList().length, 1);
+  assertElementsEquals(msg.getPackedRepeatedInt32StringList(), ['-12345']);
+  assertEquals(msg.getPackedRepeatedUint32StringList().length, 1);
+  assertElementsEquals(msg.getPackedRepeatedUint32StringList(), ['12345']);
+  assertEquals(msg.getPackedRepeatedInt64StringList().length, 1);
+  assertElementsEquals(msg.getPackedRepeatedInt64StringList(),
+      ['-123456789012345']);
+  assertEquals(msg.getPackedRepeatedUint64StringList().length, 1);
+  assertElementsEquals(msg.getPackedRepeatedUint64StringList(),
+      ['987654321098765']);
+}
+
+
+/**
+ * Helper: verify that all expected extensions are present.
+ * @param {!proto.jspb.test.TestExtendable} msg
+ */
+function checkExtensions(msg) {
+  assertEquals(-42,
+      msg.getExtension(proto.jspb.test.extendOptionalInt32));
+  assertEquals(-0x7fffffff00000000,
+      msg.getExtension(proto.jspb.test.extendOptionalInt64));
+  assertEquals(0x80000000,
+      msg.getExtension(proto.jspb.test.extendOptionalUint32));
+  assertEquals(0xf000000000000000,
+      msg.getExtension(proto.jspb.test.extendOptionalUint64));
+  assertEquals(-100,
+      msg.getExtension(proto.jspb.test.extendOptionalSint32));
+  assertEquals(-0x8000000000000000,
+      msg.getExtension(proto.jspb.test.extendOptionalSint64));
+  assertEquals(1234,
+      msg.getExtension(proto.jspb.test.extendOptionalFixed32));
+  assertEquals(0x1234567800000000,
+      msg.getExtension(proto.jspb.test.extendOptionalFixed64));
+  assertEquals(-1234,
+      msg.getExtension(proto.jspb.test.extendOptionalSfixed32));
+  assertEquals(-0x1234567800000000,
+      msg.getExtension(proto.jspb.test.extendOptionalSfixed64));
+  assertEquals(1.5,
+      msg.getExtension(proto.jspb.test.extendOptionalFloat));
+  assertEquals(-1.5,
+      msg.getExtension(proto.jspb.test.extendOptionalDouble));
+  assertEquals(true,
+      msg.getExtension(proto.jspb.test.extendOptionalBool));
+  assertEquals('hello world',
+      msg.getExtension(proto.jspb.test.extendOptionalString));
+  assertEquals(true,
+      bytesCompare(msg.getExtension(proto.jspb.test.extendOptionalBytes),
+        'bytes'));
+  assertEquals(16,
+      msg.getExtension(
+          proto.jspb.test.ExtendsWithMessage.optionalExtension).getFoo());
+  assertEquals(proto.jspb.test.ForeignEnum.FOREIGN_FOO,
+      msg.getExtension(proto.jspb.test.extendOptionalForeignEnum));
+  assertEquals('-12345',
+      msg.getExtension(proto.jspb.test.extendOptionalInt32String));
+  assertEquals('12345',
+      msg.getExtension(proto.jspb.test.extendOptionalUint32String));
+  assertEquals('-123456789012345',
+      msg.getExtension(proto.jspb.test.extendOptionalInt64String));
+  assertEquals('987654321098765',
+      msg.getExtension(proto.jspb.test.extendOptionalUint64String));
+
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedInt32List),
+      [-42]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedInt64List),
+      [-0x7fffffff00000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedUint32List),
+      [0x80000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedUint64List),
+      [0xf000000000000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedSint32List),
+      [-100]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedSint64List),
+      [-0x8000000000000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedFixed32List),
+      [1234]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedFixed64List),
+      [0x1234567800000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedSfixed32List),
+      [-1234]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedSfixed64List),
+      [-0x1234567800000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedFloatList),
+      [1.5]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedDoubleList),
+      [-1.5]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedBoolList),
+      [true]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedStringList),
+      ['hello world']);
+  assertEquals(true,
+      bytesCompare(
+          msg.getExtension(proto.jspb.test.extendRepeatedBytesList)[0],
+          'bytes'));
+  assertEquals(1000,
+      msg.getExtension(
+          proto.jspb.test.ExtendsWithMessage.repeatedExtensionList)[0]
+      .getFoo());
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedForeignEnumList),
+      [proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedInt32StringList),
+      ['-12345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedUint32StringList),
+      ['12345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedInt64StringList),
+      ['-123456789012345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendRepeatedUint64StringList),
+      ['987654321098765']);
+
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedInt32List),
+      [-42]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedInt64List),
+      [-0x7fffffff00000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedUint32List),
+      [0x80000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedUint64List),
+      [0xf000000000000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedSint32List),
+      [-100]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedSint64List),
+      [-0x8000000000000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedFixed32List),
+      [1234]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedFixed64List),
+      [0x1234567800000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedSfixed32List),
+      [-1234]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedSfixed64List),
+      [-0x1234567800000000]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedFloatList),
+      [1.5]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedDoubleList),
+      [-1.5]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedBoolList),
+      [true]);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedForeignEnumList),
+      [proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedInt32StringList),
+      ['-12345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedUint32StringList),
+      ['12345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedInt64StringList),
+      ['-123456789012345']);
+  assertElementsEquals(
+      msg.getExtension(proto.jspb.test.extendPackedRepeatedUint64StringList),
+      ['987654321098765']);
+}
+
+
+describe('protoBinaryTest', function() {
+  /**
+   * Tests a basic serialization-deserializaton round-trip with all supported
+   * field types (on the TestAllTypes message type).
+   */
+  it('testRoundTrip', function() {
+    var msg = new proto.jspb.test.TestAllTypes();
+    fillAllFields(msg);
+    var encoded = msg.serializeBinary();
+    var decoded = proto.jspb.test.TestAllTypes.deserializeBinary(encoded);
+    checkAllFields(decoded);
+  });
+
+
+  /**
+   * Helper: fill all extension values.
+   * @param {proto.jspb.test.TestExtendable} msg
+   */
+  function fillExtensions(msg) {
+    msg.setExtension(
+        proto.jspb.test.extendOptionalInt32, -42);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalInt64, -0x7fffffff00000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalUint32, 0x80000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalUint64, 0xf000000000000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalSint32, -100);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalSint64, -0x8000000000000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalFixed32, 1234);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalFixed64, 0x1234567800000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalSfixed32, -1234);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalSfixed64, -0x1234567800000000);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalFloat, 1.5);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalDouble, -1.5);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalBool, true);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalString, 'hello world');
+    msg.setExtension(
+        proto.jspb.test.extendOptionalBytes, 'bytes');
+    var submsg = new proto.jspb.test.ExtendsWithMessage();
+    submsg.setFoo(16);
+    msg.setExtension(
+        proto.jspb.test.ExtendsWithMessage.optionalExtension, submsg);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalForeignEnum,
+        proto.jspb.test.ForeignEnum.FOREIGN_FOO);
+    msg.setExtension(
+        proto.jspb.test.extendOptionalInt32String, '-12345');
+    msg.setExtension(
+        proto.jspb.test.extendOptionalUint32String, '12345');
+    msg.setExtension(
+        proto.jspb.test.extendOptionalInt64String, '-123456789012345');
+    msg.setExtension(
+        proto.jspb.test.extendOptionalUint64String, '987654321098765');
+
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedInt32List, [-42]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedInt64List, [-0x7fffffff00000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedUint32List, [0x80000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedUint64List, [0xf000000000000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedSint32List, [-100]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedSint64List, [-0x8000000000000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedFixed32List, [1234]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedFixed64List, [0x1234567800000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedSfixed32List, [-1234]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedSfixed64List, [-0x1234567800000000]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedFloatList, [1.5]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedDoubleList, [-1.5]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedBoolList, [true]);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedStringList, ['hello world']);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedBytesList, ['bytes']);
+    submsg = new proto.jspb.test.ExtendsWithMessage();
+    submsg.setFoo(1000);
+    msg.setExtension(
+        proto.jspb.test.ExtendsWithMessage.repeatedExtensionList, [submsg]);
+    msg.setExtension(proto.jspb.test.extendRepeatedForeignEnumList,
+        [proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedInt32StringList, ['-12345']);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedUint32StringList, ['12345']);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedInt64StringList, ['-123456789012345']);
+    msg.setExtension(
+        proto.jspb.test.extendRepeatedUint64StringList, ['987654321098765']);
+
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedInt32List, [-42]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedInt64List, [-0x7fffffff00000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedUint32List, [0x80000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedUint64List, [0xf000000000000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedSint32List, [-100]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedSint64List, [-0x8000000000000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedFixed32List, [1234]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedFixed64List, [0x1234567800000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedSfixed32List, [-1234]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedSfixed64List,
+        [-0x1234567800000000]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedFloatList, [1.5]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedDoubleList, [-1.5]);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedBoolList, [true]);
+    msg.setExtension(proto.jspb.test.extendPackedRepeatedForeignEnumList,
+        [proto.jspb.test.ForeignEnum.FOREIGN_FOO]);
+
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedInt32StringList,
+        ['-12345']);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedUint32StringList,
+        ['12345']);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedInt64StringList,
+        ['-123456789012345']);
+    msg.setExtension(
+        proto.jspb.test.extendPackedRepeatedUint64StringList,
+        ['987654321098765']);
+  }
+
+
+  /**
+   * Tests extension serialization and deserialization.
+   */
+  it('testExtensions', function() {
+    var msg = new proto.jspb.test.TestExtendable();
+    fillExtensions(msg);
+    var encoded = msg.serializeBinary();
+    var decoded = proto.jspb.test.TestExtendable.deserializeBinary(encoded);
+    checkExtensions(decoded);
+  });
+});
diff --git a/js/binary/reader.js b/js/binary/reader.js
new file mode 100644
index 00000000..abcd1660
--- /dev/null
+++ b/js/binary/reader.js
@@ -0,0 +1,1127 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains utilities for converting binary,
+ * wire-format protocol buffers into Javascript data structures.
+ *
+ * jspb's BinaryReader class wraps the BinaryDecoder class to add methods
+ * that understand the protocol buffer syntax and can do the type checking and
+ * bookkeeping necessary to parse trees of nested messages.
+ *
+ * Major caveat - Users of this library _must_ keep their Javascript proto
+ * parsing code in sync with the original .proto file - presumably you'll be
+ * using the typed jspb code generator, but if you bypass that you'll need
+ * to keep things in sync by hand.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.BinaryReader');
+
+goog.require('goog.asserts');
+goog.require('jspb.BinaryConstants');
+goog.require('jspb.BinaryDecoder');
+
+
+
+/**
+ * BinaryReader implements the decoders for all the wire types specified in
+ * https://developers.google.com/protocol-buffers/docs/encoding.
+ *
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @constructor
+ * @struct
+ */
+jspb.BinaryReader = function(opt_bytes, opt_start, opt_length) {
+  /**
+   * Wire-format decoder.
+   * @private {!jspb.BinaryDecoder}
+   */
+  this.decoder_ = jspb.BinaryDecoder.alloc(opt_bytes, opt_start, opt_length);
+
+  /**
+   * Cursor immediately before the field tag.
+   * @private {number}
+   */
+  this.fieldCursor_ = this.decoder_.getCursor();
+
+  /**
+   * Field number of the next field in the buffer, filled in by nextField().
+   * @private {number}
+   */
+  this.nextField_ = jspb.BinaryConstants.INVALID_FIELD_NUMBER;
+
+  /**
+   * Wire type of the next proto field in the buffer, filled in by
+   * nextField().
+   * @private {jspb.BinaryConstants.WireType}
+   */
+  this.nextWireType_ = jspb.BinaryConstants.WireType.INVALID;
+
+  /**
+   * Set to true if this reader encountered an error due to corrupt data.
+   * @private {boolean}
+   */
+  this.error_ = false;
+
+  /**
+   * User-defined reader callbacks.
+   * @private {Object.<string, function(!jspb.BinaryReader):*>}
+   */
+  this.readCallbacks_ = null;
+};
+
+
+/**
+ * Global pool of BinaryReader instances.
+ * @private {!Array.<!jspb.BinaryReader>}
+ */
+jspb.BinaryReader.instanceCache_ = [];
+
+
+/**
+ * Pops an instance off the instance cache, or creates one if the cache is
+ * empty.
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @return {!jspb.BinaryReader}
+ */
+jspb.BinaryReader.alloc =
+    function(opt_bytes, opt_start, opt_length) {
+  if (jspb.BinaryReader.instanceCache_.length) {
+    var newReader = jspb.BinaryReader.instanceCache_.pop();
+    if (opt_bytes) {
+      newReader.decoder_.setBlock(opt_bytes, opt_start, opt_length);
+    }
+    return newReader;
+  } else {
+    return new jspb.BinaryReader(opt_bytes, opt_start, opt_length);
+  }
+};
+
+
+/**
+ * Alias for the above method.
+ * @param {jspb.ByteSource=} opt_bytes The bytes we're reading from.
+ * @param {number=} opt_start The optional offset to start reading at.
+ * @param {number=} opt_length The optional length of the block to read -
+ *     we'll throw an assertion if we go off the end of the block.
+ * @return {!jspb.BinaryReader}
+ */
+jspb.BinaryReader.prototype.alloc = jspb.BinaryReader.alloc;
+
+
+/**
+ * Puts this instance back in the instance cache.
+ */
+jspb.BinaryReader.prototype.free = function() {
+  this.decoder_.clear();
+  this.nextField_ = jspb.BinaryConstants.INVALID_FIELD_NUMBER;
+  this.nextWireType_ = jspb.BinaryConstants.WireType.INVALID;
+  this.error_ = false;
+  this.readCallbacks_ = null;
+
+  if (jspb.BinaryReader.instanceCache_.length < 100) {
+    jspb.BinaryReader.instanceCache_.push(this);
+  }
+};
+
+
+/**
+ * Returns the cursor immediately before the current field's tag.
+ * @return {number} The internal read cursor.
+ */
+jspb.BinaryReader.prototype.getFieldCursor = function() {
+  return this.fieldCursor_;
+};
+
+
+/**
+ * Returns the internal read cursor.
+ * @return {number} The internal read cursor.
+ */
+jspb.BinaryReader.prototype.getCursor = function() {
+  return this.decoder_.getCursor();
+};
+
+
+/**
+ * Returns the raw buffer.
+ * @return {Uint8Array} The raw buffer.
+ */
+jspb.BinaryReader.prototype.getBuffer = function() {
+  return this.decoder_.getBuffer();
+};
+
+
+/**
+ * @return {number} The field number of the next field in the buffer, or
+ *     INVALID_FIELD_NUMBER if there is no next field.
+ */
+jspb.BinaryReader.prototype.getFieldNumber = function() {
+  return this.nextField_;
+};
+
+
+/**
+ * @return {jspb.BinaryConstants.WireType} The wire type of the next field
+ *     in the stream, or WireType.INVALID if there is no next field.
+ */
+jspb.BinaryReader.prototype.getWireType = function() {
+  return this.nextWireType_;
+};
+
+
+/**
+ * @return {boolean} Whether the current wire type is an end-group tag. Used as
+ * an exit condition in decoder loops in generated code.
+ */
+jspb.BinaryReader.prototype.isEndGroup = function() {
+  return this.nextWireType_ == jspb.BinaryConstants.WireType.END_GROUP;
+};
+
+
+/**
+ * Returns true if this reader hit an error due to corrupt data.
+ * @return {boolean}
+ */
+jspb.BinaryReader.prototype.getError = function() {
+  return this.error_ || this.decoder_.getError();
+};
+
+
+/**
+ * Points this reader at a new block of bytes.
+ * @param {!Uint8Array} bytes The block of bytes we're reading from.
+ * @param {number} start The offset to start reading at.
+ * @param {number} length The length of the block to read.
+ */
+jspb.BinaryReader.prototype.setBlock = function(bytes, start, length) {
+  this.decoder_.setBlock(bytes, start, length);
+  this.nextField_ = jspb.BinaryConstants.INVALID_FIELD_NUMBER;
+  this.nextWireType_ = jspb.BinaryConstants.WireType.INVALID;
+};
+
+
+/**
+ * Rewinds the stream cursor to the beginning of the buffer and resets all
+ * internal state.
+ */
+jspb.BinaryReader.prototype.reset = function() {
+  this.decoder_.reset();
+  this.nextField_ = jspb.BinaryConstants.INVALID_FIELD_NUMBER;
+  this.nextWireType_ = jspb.BinaryConstants.WireType.INVALID;
+};
+
+
+/**
+ * Advances the stream cursor by the given number of bytes.
+ * @param {number} count The number of bytes to advance by.
+ */
+jspb.BinaryReader.prototype.advance = function(count) {
+  this.decoder_.advance(count);
+};
+
+
+/**
+ * Reads the next field header in the stream if there is one, returns true if
+ * we saw a valid field header or false if we've read the whole stream.
+ * Throws an error if we encountered a deprecated START_GROUP/END_GROUP field.
+ * @return {boolean} True if the stream contains more fields.
+ */
+jspb.BinaryReader.prototype.nextField = function() {
+  // If we're at the end of the block, there are no more fields.
+  if (this.decoder_.atEnd()) {
+    return false;
+  }
+
+  // If we hit an error decoding the previous field, stop now before we
+  // try to decode anything else
+  if (this.getError()) {
+    goog.asserts.fail('Decoder hit an error');
+    return false;
+  }
+
+  // Otherwise just read the header of the next field.
+  this.fieldCursor_ = this.decoder_.getCursor();
+  var header = this.decoder_.readUnsignedVarint32();
+
+  var nextField = header >>> 3;
+  var nextWireType = /** @type {jspb.BinaryConstants.WireType} */
+      (header & 0x7);
+
+  // If the wire type isn't one of the valid ones, something's broken.
+  if (nextWireType != jspb.BinaryConstants.WireType.VARINT &&
+      nextWireType != jspb.BinaryConstants.WireType.FIXED32 &&
+      nextWireType != jspb.BinaryConstants.WireType.FIXED64 &&
+      nextWireType != jspb.BinaryConstants.WireType.DELIMITED &&
+      nextWireType != jspb.BinaryConstants.WireType.START_GROUP &&
+      nextWireType != jspb.BinaryConstants.WireType.END_GROUP) {
+    goog.asserts.fail('Invalid wire type');
+    this.error_ = true;
+    return false;
+  }
+
+  this.nextField_ = nextField;
+  this.nextWireType_ = nextWireType;
+
+  return true;
+};
+
+
+/**
+ * Winds the reader back to just before this field's header.
+ */
+jspb.BinaryReader.prototype.unskipHeader = function() {
+  this.decoder_.unskipVarint((this.nextField_ << 3) | this.nextWireType_);
+};
+
+
+/**
+ * Skips all contiguous fields whose header matches the one we just read.
+ */
+jspb.BinaryReader.prototype.skipMatchingFields = function() {
+  var field = this.nextField_;
+  this.unskipHeader();
+
+  while (this.nextField() && (this.getFieldNumber() == field)) {
+    this.skipField();
+  }
+
+  if (!this.decoder_.atEnd()) {
+    this.unskipHeader();
+  }
+};
+
+
+/**
+ * Skips over the next varint field in the binary stream.
+ */
+jspb.BinaryReader.prototype.skipVarintField = function() {
+  if (this.nextWireType_ != jspb.BinaryConstants.WireType.VARINT) {
+    goog.asserts.fail('Invalid wire type for skipVarintField');
+    this.skipField();
+    return;
+  }
+
+  this.decoder_.skipVarint();
+};
+
+
+/**
+ * Skips over the next delimited field in the binary stream.
+ */
+jspb.BinaryReader.prototype.skipDelimitedField = function() {
+  if (this.nextWireType_ != jspb.BinaryConstants.WireType.DELIMITED) {
+    goog.asserts.fail('Invalid wire type for skipDelimitedField');
+    this.skipField();
+    return;
+  }
+
+  var length = this.decoder_.readUnsignedVarint32();
+  this.decoder_.advance(length);
+};
+
+
+/**
+ * Skips over the next fixed32 field in the binary stream.
+ */
+jspb.BinaryReader.prototype.skipFixed32Field = function() {
+  if (this.nextWireType_ != jspb.BinaryConstants.WireType.FIXED32) {
+    goog.asserts.fail('Invalid wire type for skipFixed32Field');
+    this.skipField();
+    return;
+  }
+
+  this.decoder_.advance(4);
+};
+
+
+/**
+ * Skips over the next fixed64 field in the binary stream.
+ */
+jspb.BinaryReader.prototype.skipFixed64Field = function() {
+  if (this.nextWireType_ != jspb.BinaryConstants.WireType.FIXED64) {
+    goog.asserts.fail('Invalid wire type for skipFixed64Field');
+    this.skipField();
+    return;
+  }
+
+  this.decoder_.advance(8);
+};
+
+
+/**
+ * Skips over the next group field in the binary stream.
+ */
+jspb.BinaryReader.prototype.skipGroup = function() {
+  // Keep a stack of start-group tags that must be matched by end-group tags.
+  var nestedGroups = [this.nextField_];
+  do {
+    if (!this.nextField()) {
+      goog.asserts.fail('Unmatched start-group tag: stream EOF');
+      this.error_ = true;
+      return;
+    }
+    if (this.nextWireType_ ==
+        jspb.BinaryConstants.WireType.START_GROUP) {
+      // Nested group start.
+      nestedGroups.push(this.nextField_);
+    } else if (this.nextWireType_ ==
+               jspb.BinaryConstants.WireType.END_GROUP) {
+      // Group end: check that it matches top-of-stack.
+      if (this.nextField_ != nestedGroups.pop()) {
+        goog.asserts.fail('Unmatched end-group tag');
+        this.error_ = true;
+        return;
+      }
+    }
+  } while (nestedGroups.length > 0);
+};
+
+
+/**
+ * Skips over the next field in the binary stream - this is useful if we're
+ * decoding a message that contain unknown fields.
+ */
+jspb.BinaryReader.prototype.skipField = function() {
+  switch (this.nextWireType_) {
+    case jspb.BinaryConstants.WireType.VARINT:
+      this.skipVarintField();
+      break;
+    case jspb.BinaryConstants.WireType.FIXED64:
+      this.skipFixed64Field();
+      break;
+    case jspb.BinaryConstants.WireType.DELIMITED:
+      this.skipDelimitedField();
+      break;
+    case jspb.BinaryConstants.WireType.FIXED32:
+      this.skipFixed32Field();
+      break;
+    case jspb.BinaryConstants.WireType.START_GROUP:
+      this.skipGroup();
+      break;
+    default:
+      goog.asserts.fail('Invalid wire encoding for field.');
+  }
+};
+
+
+/**
+ * Registers a user-defined read callback.
+ * @param {string} callbackName
+ * @param {function(!jspb.BinaryReader):*} callback
+ */
+jspb.BinaryReader.prototype.registerReadCallback =
+    function(callbackName, callback) {
+  if (goog.isNull(this.readCallbacks_)) {
+    this.readCallbacks_ = {};
+  }
+  goog.asserts.assert(!this.readCallbacks_[callbackName]);
+  this.readCallbacks_[callbackName] = callback;
+};
+
+
+/**
+ * Runs a registered read callback.
+ * @param {string} callbackName The name the callback is registered under.
+ * @return {*} The value returned by the callback.
+ */
+jspb.BinaryReader.prototype.runReadCallback = function(callbackName) {
+  goog.asserts.assert(!goog.isNull(this.readCallbacks_));
+  var callback = this.readCallbacks_[callbackName];
+  goog.asserts.assert(callback);
+  return callback(this);
+};
+
+
+/**
+ * Reads a field of any valid non-message type from the binary stream.
+ * @param {jspb.BinaryConstants.FieldType} fieldType
+ * @return {jspb.AnyFieldType}
+ */
+jspb.BinaryReader.prototype.readAny = function(fieldType) {
+  this.nextWireType_ = jspb.BinaryConstants.FieldTypeToWireType(fieldType);
+  var fieldTypes = jspb.BinaryConstants.FieldType;
+  switch (fieldType) {
+    case fieldTypes.DOUBLE:
+      return this.readDouble();
+    case fieldTypes.FLOAT:
+      return this.readFloat();
+    case fieldTypes.INT64:
+      return this.readInt64();
+    case fieldTypes.UINT64:
+      return this.readUint64();
+    case fieldTypes.INT32:
+      return this.readInt32();
+    case fieldTypes.FIXED64:
+      return this.readFixed64();
+    case fieldTypes.FIXED32:
+      return this.readFixed32();
+    case fieldTypes.BOOL:
+      return this.readBool();
+    case fieldTypes.STRING:
+      return this.readString();
+    case fieldTypes.GROUP:
+      goog.asserts.fail('Group field type not supported in readAny()');
+    case fieldTypes.MESSAGE:
+      goog.asserts.fail('Message field type not supported in readAny()');
+    case fieldTypes.BYTES:
+      return this.readBytes();
+    case fieldTypes.UINT32:
+      return this.readUint32();
+    case fieldTypes.ENUM:
+      return this.readEnum();
+    case fieldTypes.SFIXED32:
+      return this.readSfixed32();
+    case fieldTypes.SFIXED64:
+      return this.readSfixed64();
+    case fieldTypes.SINT32:
+      return this.readSint32();
+    case fieldTypes.SINT64:
+      return this.readSint64();
+    case fieldTypes.FHASH64:
+      return this.readFixedHash64();
+    case fieldTypes.VHASH64:
+      return this.readVarintHash64();
+    default:
+      goog.asserts.fail('Invalid field type in readAny()');
+  }
+  return 0;
+};
+
+
+/**
+ * Deserialize a proto into the provided message object using the provided
+ * reader function. This function is templated as we currently have one client
+ * who is using manual deserialization instead of the code-generated versions.
+ * @template T
+ * @param {T} message
+ * @param {function(T, !jspb.BinaryReader)} reader
+ */
+jspb.BinaryReader.prototype.readMessage = function(message, reader) {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.DELIMITED);
+
+  // Save the current endpoint of the decoder and move it to the end of the
+  // embedded message.
+  var oldEnd = this.decoder_.getEnd();
+  var length = this.decoder_.readUnsignedVarint32();
+  var newEnd = this.decoder_.getCursor() + length;
+  this.decoder_.setEnd(newEnd);
+
+  // Deserialize the embedded message.
+  reader(message, this);
+
+  // Advance the decoder past the embedded message and restore the endpoint.
+  this.decoder_.setCursor(newEnd);
+  this.decoder_.setEnd(oldEnd);
+};
+
+
+/**
+ * Deserialize a proto into the provided message object using the provided
+ * reader function, assuming that the message is serialized as a group
+ * with the given tag.
+ * @template T
+ * @param {number} field
+ * @param {T} message
+ * @param {function(T, !jspb.BinaryReader)} reader
+ */
+jspb.BinaryReader.prototype.readGroup =
+    function(field, message, reader) {
+  // Ensure that the wire type is correct.
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.START_GROUP);
+  // Ensure that the field number is correct.
+  goog.asserts.assert(this.nextField_ == field);
+
+  // Deserialize the message. The deserialization will stop at an END_GROUP tag.
+  reader(message, this);
+
+  if (!this.error_ &&
+      this.nextWireType_ != jspb.BinaryConstants.WireType.END_GROUP) {
+    goog.asserts.fail('Group submessage did not end with an END_GROUP tag');
+    this.error_ = true;
+  }
+};
+
+
+/**
+ * Return a decoder that wraps the current delimited field.
+ * @return {!jspb.BinaryDecoder}
+ */
+jspb.BinaryReader.prototype.getFieldDecoder = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.DELIMITED);
+
+  var length = this.decoder_.readUnsignedVarint32();
+  var start = this.decoder_.getCursor();
+  var end = start + length;
+
+  var innerDecoder = jspb.BinaryDecoder.alloc(this.decoder_.getBuffer(),
+                                                 start, length);
+  this.decoder_.setCursor(end);
+  return innerDecoder;
+};
+
+
+/**
+ * Reads a signed 32-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the signed 32-bit integer field.
+ */
+jspb.BinaryReader.prototype.readInt32 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readSignedVarint32();
+};
+
+
+/**
+ * Reads a signed 32-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * Returns the value as a string.
+ *
+ * @return {string} The value of the signed 32-bit integer field as a decimal
+ * string.
+ */
+jspb.BinaryReader.prototype.readInt32String = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readSignedVarint32String();
+};
+
+
+/**
+ * Reads a signed 64-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the signed 64-bit integer field.
+ */
+jspb.BinaryReader.prototype.readInt64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readSignedVarint64();
+};
+
+
+/**
+ * Reads a signed 64-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * Returns the value as a string.
+ *
+ * @return {string} The value of the signed 64-bit integer field as a decimal
+ * string.
+ */
+jspb.BinaryReader.prototype.readInt64String = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readSignedVarint64String();
+};
+
+
+/**
+ * Reads an unsigned 32-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the unsigned 32-bit integer field.
+ */
+jspb.BinaryReader.prototype.readUint32 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readUnsignedVarint32();
+};
+
+
+/**
+ * Reads an unsigned 32-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * Returns the value as a string.
+ *
+ * @return {string} The value of the unsigned 32-bit integer field as a decimal
+ * string.
+ */
+jspb.BinaryReader.prototype.readUint32String = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readUnsignedVarint32String();
+};
+
+
+/**
+ * Reads an unsigned 64-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the unsigned 64-bit integer field.
+ */
+jspb.BinaryReader.prototype.readUint64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readUnsignedVarint64();
+};
+
+
+/**
+ * Reads an unsigned 64-bit integer field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * Returns the value as a string.
+ *
+ * @return {string} The value of the unsigned 64-bit integer field as a decimal
+ * string.
+ */
+jspb.BinaryReader.prototype.readUint64String = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readUnsignedVarint64String();
+};
+
+
+/**
+ * Reads a signed zigzag-encoded 32-bit integer field from the binary stream,
+ * or throws an error if the next field in the stream is not of the correct
+ * wire type.
+ *
+ * @return {number} The value of the signed 32-bit integer field.
+ */
+jspb.BinaryReader.prototype.readSint32 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readZigzagVarint32();
+};
+
+
+/**
+ * Reads a signed zigzag-encoded 64-bit integer field from the binary stream,
+ * or throws an error if the next field in the stream is not of the correct
+ * wire type.
+ *
+ * @return {number} The value of the signed 64-bit integer field.
+ */
+jspb.BinaryReader.prototype.readSint64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readZigzagVarint64();
+};
+
+
+/**
+ * Reads an unsigned 32-bit fixed-length integer fiield from the binary stream,
+ * or throws an error if the next field in the stream is not of the correct
+ * wire type.
+ *
+ * @return {number} The value of the double field.
+ */
+jspb.BinaryReader.prototype.readFixed32 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED32);
+  return this.decoder_.readUint32();
+};
+
+
+/**
+ * Reads an unsigned 64-bit fixed-length integer fiield from the binary stream,
+ * or throws an error if the next field in the stream is not of the correct
+ * wire type.
+ *
+ * @return {number} The value of the float field.
+ */
+jspb.BinaryReader.prototype.readFixed64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED64);
+  return this.decoder_.readUint64();
+};
+
+
+/**
+ * Reads a signed 32-bit fixed-length integer fiield from the binary stream, or
+ * throws an error if the next field in the stream is not of the correct wire
+ * type.
+ *
+ * @return {number} The value of the double field.
+ */
+jspb.BinaryReader.prototype.readSfixed32 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED32);
+  return this.decoder_.readInt32();
+};
+
+
+/**
+ * Reads a signed 64-bit fixed-length integer fiield from the binary stream, or
+ * throws an error if the next field in the stream is not of the correct wire
+ * type.
+ *
+ * @return {number} The value of the float field.
+ */
+jspb.BinaryReader.prototype.readSfixed64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED64);
+  return this.decoder_.readInt64();
+};
+
+
+/**
+ * Reads a 32-bit floating-point field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the float field.
+ */
+jspb.BinaryReader.prototype.readFloat = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED32);
+  return this.decoder_.readFloat();
+};
+
+
+/**
+ * Reads a 64-bit floating-point field from the binary stream, or throws an
+ * error if the next field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the double field.
+ */
+jspb.BinaryReader.prototype.readDouble = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED64);
+  return this.decoder_.readDouble();
+};
+
+
+/**
+ * Reads a boolean field from the binary stream, or throws an error if the next
+ * field in the stream is not of the correct wire type.
+ *
+ * @return {boolean} The value of the boolean field.
+ */
+jspb.BinaryReader.prototype.readBool = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return !!this.decoder_.readUnsignedVarint32();
+};
+
+
+/**
+ * Reads an enum field from the binary stream, or throws an error if the next
+ * field in the stream is not of the correct wire type.
+ *
+ * @return {number} The value of the enum field.
+ */
+jspb.BinaryReader.prototype.readEnum = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readSignedVarint64();
+};
+
+
+/**
+ * Reads a string field from the binary stream, or throws an error if the next
+ * field in the stream is not of the correct wire type.
+ *
+ * @return {string} The value of the string field.
+ */
+jspb.BinaryReader.prototype.readString = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.DELIMITED);
+  var length = this.decoder_.readUnsignedVarint32();
+  return this.decoder_.readString(length);
+};
+
+
+/**
+ * Reads a length-prefixed block of bytes from the binary stream, or returns
+ * null if the next field in the stream has an invalid length value.
+ *
+ * @return {Uint8Array} The block of bytes.
+ */
+jspb.BinaryReader.prototype.readBytes = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.DELIMITED);
+  var length = this.decoder_.readUnsignedVarint32();
+  return this.decoder_.readBytes(length);
+};
+
+
+/**
+ * Reads a 64-bit varint or fixed64 field from the stream and returns it as a
+ * 8-character Unicode string for use as a hash table key, or throws an error
+ * if the next field in the stream is not of the correct wire type.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryReader.prototype.readVarintHash64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.VARINT);
+  return this.decoder_.readVarintHash64();
+};
+
+
+/**
+ * Reads a 64-bit varint or fixed64 field from the stream and returns it as a
+ * 8-character Unicode string for use as a hash table key, or throws an error
+ * if the next field in the stream is not of the correct wire type.
+ *
+ * @return {string} The hash value.
+ */
+jspb.BinaryReader.prototype.readFixedHash64 = function() {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.FIXED64);
+  return this.decoder_.readFixedHash64();
+};
+
+
+/**
+ * Reads a packed scalar field using the supplied raw reader function.
+ * @param {function()} decodeMethod
+ * @return {!Array}
+ * @private
+ */
+jspb.BinaryReader.prototype.readPackedField_ = function(decodeMethod) {
+  goog.asserts.assert(
+      this.nextWireType_ == jspb.BinaryConstants.WireType.DELIMITED);
+  var length = this.decoder_.readUnsignedVarint32();
+  var end = this.decoder_.getCursor() + length;
+  var result = [];
+  while (this.decoder_.getCursor() < end) {
+    // TODO(aappleby): .call is slow
+    result.push(decodeMethod.call(this.decoder_));
+  }
+  return result;
+};
+
+
+/**
+ * Reads a packed int32 field, which consists of a length header and a list of
+ * signed varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedInt32 = function() {
+  return this.readPackedField_(this.decoder_.readSignedVarint32);
+};
+
+
+/**
+ * Reads a packed int32 field, which consists of a length header and a list of
+ * signed varints. Returns a list of strings.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedInt32String = function() {
+  return this.readPackedField_(this.decoder_.readSignedVarint32String);
+};
+
+
+/**
+ * Reads a packed int64 field, which consists of a length header and a list of
+ * signed varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedInt64 = function() {
+  return this.readPackedField_(this.decoder_.readSignedVarint64);
+};
+
+
+/**
+ * Reads a packed int64 field, which consists of a length header and a list of
+ * signed varints. Returns a list of strings.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedInt64String = function() {
+  return this.readPackedField_(this.decoder_.readSignedVarint64String);
+};
+
+
+/**
+ * Reads a packed uint32 field, which consists of a length header and a list of
+ * unsigned varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedUint32 = function() {
+  return this.readPackedField_(this.decoder_.readUnsignedVarint32);
+};
+
+
+/**
+ * Reads a packed uint32 field, which consists of a length header and a list of
+ * unsigned varints. Returns a list of strings.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedUint32String = function() {
+  return this.readPackedField_(this.decoder_.readUnsignedVarint32String);
+};
+
+
+/**
+ * Reads a packed uint64 field, which consists of a length header and a list of
+ * unsigned varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedUint64 = function() {
+  return this.readPackedField_(this.decoder_.readUnsignedVarint64);
+};
+
+
+/**
+ * Reads a packed uint64 field, which consists of a length header and a list of
+ * unsigned varints. Returns a list of strings.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedUint64String = function() {
+  return this.readPackedField_(this.decoder_.readUnsignedVarint64String);
+};
+
+
+/**
+ * Reads a packed sint32 field, which consists of a length header and a list of
+ * zigzag varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedSint32 = function() {
+  return this.readPackedField_(this.decoder_.readZigzagVarint32);
+};
+
+
+/**
+ * Reads a packed sint64 field, which consists of a length header and a list of
+ * zigzag varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedSint64 = function() {
+  return this.readPackedField_(this.decoder_.readZigzagVarint64);
+};
+
+
+/**
+ * Reads a packed fixed32 field, which consists of a length header and a list
+ * of unsigned 32-bit ints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedFixed32 = function() {
+  return this.readPackedField_(this.decoder_.readUint32);
+};
+
+
+/**
+ * Reads a packed fixed64 field, which consists of a length header and a list
+ * of unsigned 64-bit ints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedFixed64 = function() {
+  return this.readPackedField_(this.decoder_.readUint64);
+};
+
+
+/**
+ * Reads a packed sfixed32 field, which consists of a length header and a list
+ * of 32-bit ints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedSfixed32 = function() {
+  return this.readPackedField_(this.decoder_.readInt32);
+};
+
+
+/**
+ * Reads a packed sfixed64 field, which consists of a length header and a list
+ * of 64-bit ints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedSfixed64 = function() {
+  return this.readPackedField_(this.decoder_.readInt64);
+};
+
+
+/**
+ * Reads a packed float field, which consists of a length header and a list of
+ * floats.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedFloat = function() {
+  return this.readPackedField_(this.decoder_.readFloat);
+};
+
+
+/**
+ * Reads a packed double field, which consists of a length header and a list of
+ * doubles.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedDouble = function() {
+  return this.readPackedField_(this.decoder_.readDouble);
+};
+
+
+/**
+ * Reads a packed bool field, which consists of a length header and a list of
+ * unsigned varints.
+ * @return {!Array.<boolean>}
+ */
+jspb.BinaryReader.prototype.readPackedBool = function() {
+  return this.readPackedField_(this.decoder_.readBool);
+};
+
+
+/**
+ * Reads a packed enum field, which consists of a length header and a list of
+ * unsigned varints.
+ * @return {!Array.<number>}
+ */
+jspb.BinaryReader.prototype.readPackedEnum = function() {
+  return this.readPackedField_(this.decoder_.readEnum);
+};
+
+
+/**
+ * Reads a packed varint hash64 field, which consists of a length header and a
+ * list of varint hash64s.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedVarintHash64 = function() {
+  return this.readPackedField_(this.decoder_.readVarintHash64);
+};
+
+
+/**
+ * Reads a packed fixed hash64 field, which consists of a length header and a
+ * list of fixed hash64s.
+ * @return {!Array.<string>}
+ */
+jspb.BinaryReader.prototype.readPackedFixedHash64 = function() {
+  return this.readPackedField_(this.decoder_.readFixedHash64);
+};
diff --git a/js/binary/reader_test.js b/js/binary/reader_test.js
new file mode 100644
index 00000000..a6482610
--- /dev/null
+++ b/js/binary/reader_test.js
@@ -0,0 +1,889 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Test cases for jspb's binary protocol buffer reader.
+ *
+ * There are two particular magic numbers that need to be pointed out -
+ * 2^64-1025 is the largest number representable as both a double and an
+ * unsigned 64-bit integer, and 2^63-513 is the largest number representable as
+ * both a double and a signed 64-bit integer.
+ *
+ * Test suite is written using Jasmine -- see http://jasmine.github.io/
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.require('goog.testing.asserts');
+goog.require('jspb.BinaryConstants');
+goog.require('jspb.BinaryDecoder');
+goog.require('jspb.BinaryReader');
+goog.require('jspb.BinaryWriter');
+
+
+
+describe('binaryReaderTest', function() {
+  /**
+   * Tests the reader instance cache.
+   * @suppress {visibility}
+   */
+  it('testInstanceCaches', function() {
+    var writer = new jspb.BinaryWriter();
+    var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+    writer.writeMessage(1, dummyMessage, goog.nullFunction);
+    writer.writeMessage(2, dummyMessage, goog.nullFunction);
+
+    var buffer = writer.getResultBuffer();
+
+    // Empty the instance caches.
+    jspb.BinaryReader.instanceCache_ = [];
+
+    // Allocating and then freeing three decoders should leave us with three in
+    // the cache.
+
+    var decoder1 = jspb.BinaryDecoder.alloc();
+    var decoder2 = jspb.BinaryDecoder.alloc();
+    var decoder3 = jspb.BinaryDecoder.alloc();
+    decoder1.free();
+    decoder2.free();
+    decoder3.free();
+
+    assertEquals(3, jspb.BinaryDecoder.instanceCache_.length);
+    assertEquals(0, jspb.BinaryReader.instanceCache_.length);
+
+    // Allocating and then freeing a reader should remove one decoder from its
+    // cache, but it should stay stuck to the reader afterwards since we can't
+    // have a reader without a decoder.
+    jspb.BinaryReader.alloc().free();
+
+    assertEquals(2, jspb.BinaryDecoder.instanceCache_.length);
+    assertEquals(1, jspb.BinaryReader.instanceCache_.length);
+
+    // Allocating a reader should remove a reader from the cache.
+    var reader = jspb.BinaryReader.alloc(buffer);
+
+    assertEquals(2, jspb.BinaryDecoder.instanceCache_.length);
+    assertEquals(0, jspb.BinaryReader.instanceCache_.length);
+
+    // Processing the message reuses the current reader.
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    reader.readMessage(dummyMessage, function() {
+      assertEquals(0, jspb.BinaryReader.instanceCache_.length);
+    });
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    reader.readMessage(dummyMessage, function() {
+      assertEquals(0, jspb.BinaryReader.instanceCache_.length);
+    });
+
+    assertEquals(false, reader.nextField());
+
+    assertEquals(2, jspb.BinaryDecoder.instanceCache_.length);
+    assertEquals(0, jspb.BinaryReader.instanceCache_.length);
+
+    // Freeing the reader should put it back into the cache.
+    reader.free();
+
+    assertEquals(2, jspb.BinaryDecoder.instanceCache_.length);
+    assertEquals(1, jspb.BinaryReader.instanceCache_.length);
+  });
+
+
+  /**
+   * @param {number} x
+   * @return {number}
+   */
+  function truncate(x) {
+    var temp = new Float32Array(1);
+    temp[0] = x;
+    return temp[0];
+  }
+
+
+  /**
+   * Verifies that misuse of the reader class triggers assertions.
+   * @suppress {checkTypes|visibility}
+   */
+  it('testReadErrors', function() {
+    // Calling readMessage on a non-delimited field should trigger an
+    // assertion.
+    var reader = jspb.BinaryReader.alloc([8, 1]);
+    var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+    reader.nextField();
+    assertThrows(function() {
+      reader.readMessage(dummyMessage, goog.nullFunction);
+    });
+
+    // Reading past the end of the stream should trigger an assertion.
+    reader = jspb.BinaryReader.alloc([9, 1]);
+    reader.nextField();
+    assertThrows(function() {reader.readFixed64()});
+
+    // Reading past the end of a submessage should trigger an assertion.
+    reader = jspb.BinaryReader.alloc([10, 4, 13, 1, 1, 1]);
+    reader.nextField();
+    reader.readMessage(dummyMessage, function() {
+      reader.nextField();
+      assertThrows(function() {reader.readFixed32()});
+    });
+
+    // Skipping an invalid field should trigger an assertion.
+    reader = jspb.BinaryReader.alloc([12, 1]);
+    reader.nextWireType_ = 1000;
+    assertThrows(function() {reader.skipField()});
+
+    // Reading fields with the wrong wire type should assert.
+    reader = jspb.BinaryReader.alloc([9, 0, 0, 0, 0, 0, 0, 0, 0]);
+    reader.nextField();
+    assertThrows(function() {reader.readInt32()});
+    assertThrows(function() {reader.readInt32String()});
+    assertThrows(function() {reader.readInt64()});
+    assertThrows(function() {reader.readInt64String()});
+    assertThrows(function() {reader.readUint32()});
+    assertThrows(function() {reader.readUint32String()});
+    assertThrows(function() {reader.readUint64()});
+    assertThrows(function() {reader.readUint64String()});
+    assertThrows(function() {reader.readSint32()});
+    assertThrows(function() {reader.readBool()});
+    assertThrows(function() {reader.readEnum()});
+
+    reader = jspb.BinaryReader.alloc([8, 1]);
+    reader.nextField();
+    assertThrows(function() {reader.readFixed32()});
+    assertThrows(function() {reader.readFixed64()});
+    assertThrows(function() {reader.readSfixed32()});
+    assertThrows(function() {reader.readSfixed64()});
+    assertThrows(function() {reader.readFloat()});
+    assertThrows(function() {reader.readDouble()});
+
+    assertThrows(function() {reader.readString()});
+    assertThrows(function() {reader.readBytes()});
+  });
+
+
+  /**
+   * Tests encoding and decoding of unsigned field types.
+   * @param {Function} readField
+   * @param {Function} writeField
+   * @param {number} epsilon
+   * @param {number} upperLimit
+   * @param {Function} filter
+   * @private
+   * @suppress {missingProperties}
+   */
+  function doTestUnsignedField_(readField,
+      writeField, epsilon, upperLimit, filter) {
+    assertNotNull(readField);
+    assertNotNull(writeField);
+
+    var writer = new jspb.BinaryWriter();
+
+    // Encode zero and limits.
+    writeField.call(writer, 1, filter(0));
+    writeField.call(writer, 2, filter(epsilon));
+    writeField.call(writer, 3, filter(upperLimit));
+
+    // Encode positive values.
+    for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+      writeField.call(writer, 4, filter(cursor));
+    }
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    // Check zero and limits.
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(filter(0), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    assertEquals(filter(epsilon), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(3, reader.getFieldNumber());
+    assertEquals(filter(upperLimit), readField.call(reader));
+
+    // Check positive values.
+    for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+      reader.nextField();
+      if (4 != reader.getFieldNumber()) throw 'fail!';
+      if (filter(cursor) != readField.call(reader)) throw 'fail!';
+    }
+  };
+
+
+  /**
+   * Tests encoding and decoding of signed field types.
+   * @param {Function} readField
+   * @param {Function} writeField
+   * @param {number} epsilon
+   * @param {number} lowerLimit
+   * @param {number} upperLimit
+   * @param {Function} filter
+   * @private
+   * @suppress {missingProperties}
+   */
+  function doTestSignedField_(readField,
+      writeField, epsilon, lowerLimit, upperLimit, filter) {
+    var writer = new jspb.BinaryWriter();
+
+    // Encode zero and limits.
+    writeField.call(writer, 1, filter(lowerLimit));
+    writeField.call(writer, 2, filter(-epsilon));
+    writeField.call(writer, 3, filter(0));
+    writeField.call(writer, 4, filter(epsilon));
+    writeField.call(writer, 5, filter(upperLimit));
+
+    var inputValues = [];
+
+    // Encode negative values.
+    for (var cursor = lowerLimit; cursor < -epsilon; cursor /= 1.1) {
+      var val = filter(cursor);
+      writeField.call(writer, 6, val);
+      inputValues.push({
+        fieldNumber: 6,
+        value: val
+      });
+    }
+
+    // Encode positive values.
+    for (var cursor = epsilon; cursor < upperLimit; cursor *= 1.1) {
+      var val = filter(cursor);
+      writeField.call(writer, 7, val);
+      inputValues.push({
+        fieldNumber: 7,
+        value: val
+      });
+    }
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    // Check zero and limits.
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(filter(lowerLimit), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    assertEquals(filter(-epsilon), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(3, reader.getFieldNumber());
+    assertEquals(filter(0), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(4, reader.getFieldNumber());
+    assertEquals(filter(epsilon), readField.call(reader));
+
+    reader.nextField();
+    assertEquals(5, reader.getFieldNumber());
+    assertEquals(filter(upperLimit), readField.call(reader));
+
+    for (var i = 0; i < inputValues.length; i++) {
+      var expected = inputValues[i];
+      reader.nextField();
+      assertEquals(expected.fieldNumber, reader.getFieldNumber());
+      assertEquals(expected.value, readField.call(reader));
+    }
+  };
+
+
+  /**
+   * Tests fields that use varint encoding.
+   */
+  it('testVarintFields', function() {
+    assertNotNull(jspb.BinaryReader.prototype.readUint32);
+    assertNotNull(jspb.BinaryReader.prototype.writeUint32);
+    assertNotNull(jspb.BinaryReader.prototype.readUint64);
+    assertNotNull(jspb.BinaryReader.prototype.writeUint64);
+    assertNotNull(jspb.BinaryReader.prototype.readBool);
+    assertNotNull(jspb.BinaryReader.prototype.writeBool);
+    doTestUnsignedField_(
+        jspb.BinaryReader.prototype.readUint32,
+        jspb.BinaryWriter.prototype.writeUint32,
+        1, Math.pow(2, 32) - 1, Math.round);
+
+    doTestUnsignedField_(
+        jspb.BinaryReader.prototype.readUint64,
+        jspb.BinaryWriter.prototype.writeUint64,
+        1, Math.pow(2, 64) - 1025, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readInt32,
+        jspb.BinaryWriter.prototype.writeInt32,
+        1, -Math.pow(2, 31), Math.pow(2, 31) - 1, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readInt64,
+        jspb.BinaryWriter.prototype.writeInt64,
+        1, -Math.pow(2, 63), Math.pow(2, 63) - 513, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readEnum,
+        jspb.BinaryWriter.prototype.writeEnum,
+        1, -Math.pow(2, 31), Math.pow(2, 31) - 1, Math.round);
+
+    doTestUnsignedField_(
+        jspb.BinaryReader.prototype.readBool,
+        jspb.BinaryWriter.prototype.writeBool,
+        1, 1, function(x) { return !!x; });
+  });
+
+
+  /**
+   * Tests 64-bit fields that are handled as strings.
+   */
+  it('testStringInt64Fields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var testSignedData = [
+        '2730538252207801776',
+        '-2688470994844604560',
+        '3398529779486536359',
+        '3568577411627971000',
+        '272477188847484900',
+        '-6649058714086158188',
+        '-7695254765712060806',
+        '-4525541438037104029',
+        '-4993706538836508568',
+        '4990160321893729138'
+    ];
+    var testUnsignedData = [
+        '7822732630241694882',
+        '6753602971916687352',
+        '2399935075244442116',
+        '8724292567325338867',
+        '16948784802625696584',
+        '4136275908516066934',
+        '3575388346793700364',
+        '5167142028379259461',
+        '1557573948689737699',
+        '17100725280812548567'
+    ];
+
+    for (var i = 0; i < testSignedData.length; i++) {
+      writer.writeInt64String(2 * i + 1, testSignedData[i]);
+      writer.writeUint64String(2 * i + 2, testUnsignedData[i]);
+    }
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    for (var i = 0; i < testSignedData.length; i++) {
+      reader.nextField();
+      assertEquals(2 * i + 1, reader.getFieldNumber());
+      assertEquals(testSignedData[i], reader.readInt64String());
+      reader.nextField();
+      assertEquals(2 * i + 2, reader.getFieldNumber());
+      assertEquals(testUnsignedData[i], reader.readUint64String());
+    }
+  });
+
+
+  /**
+   * Tests fields that use zigzag encoding.
+   */
+  it('testZigzagFields', function() {
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readSint32,
+        jspb.BinaryWriter.prototype.writeSint32,
+        1, -Math.pow(2, 31), Math.pow(2, 31) - 1, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readSint64,
+        jspb.BinaryWriter.prototype.writeSint64,
+        1, -Math.pow(2, 63), Math.pow(2, 63) - 513, Math.round);
+  });
+
+
+  /**
+   * Tests fields that use fixed-length encoding.
+   */
+  it('testFixedFields', function() {
+    doTestUnsignedField_(
+        jspb.BinaryReader.prototype.readFixed32,
+        jspb.BinaryWriter.prototype.writeFixed32,
+        1, Math.pow(2, 32) - 1, Math.round);
+
+    doTestUnsignedField_(
+        jspb.BinaryReader.prototype.readFixed64,
+        jspb.BinaryWriter.prototype.writeFixed64,
+        1, Math.pow(2, 64) - 1025, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readSfixed32,
+        jspb.BinaryWriter.prototype.writeSfixed32,
+        1, -Math.pow(2, 31), Math.pow(2, 31) - 1, Math.round);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readSfixed64,
+        jspb.BinaryWriter.prototype.writeSfixed64,
+        1, -Math.pow(2, 63), Math.pow(2, 63) - 513, Math.round);
+  });
+
+
+  /**
+   * Tests floating point fields.
+   */
+  it('testFloatFields', function() {
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readFloat,
+        jspb.BinaryWriter.prototype.writeFloat,
+        jspb.BinaryConstants.FLOAT32_MIN,
+        -jspb.BinaryConstants.FLOAT32_MAX,
+        jspb.BinaryConstants.FLOAT32_MAX,
+        truncate);
+
+    doTestSignedField_(
+        jspb.BinaryReader.prototype.readDouble,
+        jspb.BinaryWriter.prototype.writeDouble,
+        jspb.BinaryConstants.FLOAT64_EPS * 10,
+        -jspb.BinaryConstants.FLOAT64_MIN,
+        jspb.BinaryConstants.FLOAT64_MIN,
+        function(x) { return x; });
+  });
+
+
+  /**
+   * Tests length-delimited string fields.
+   */
+  it('testStringFields', function() {
+    var s1 = 'The quick brown fox jumps over the lazy dog.';
+    var s2 = '人人生而自由，在尊嚴和權利上一律平等。';
+
+    var writer = new jspb.BinaryWriter();
+
+    writer.writeString(1, s1);
+    writer.writeString(2, s2);
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(s1, reader.readString());
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    assertEquals(s2, reader.readString());
+  });
+
+
+  /**
+   * Tests length-delimited byte fields.
+   */
+  it('testByteFields', function() {
+    var message = [];
+    var lowerLimit = 1;
+    var upperLimit = 256;
+    var scale = 1.1;
+
+    var writer = new jspb.BinaryWriter();
+
+    for (var cursor = lowerLimit; cursor < upperLimit; cursor *= 1.1) {
+      var len = Math.round(cursor);
+      var bytes = [];
+      for (var i = 0; i < len; i++) bytes.push(i % 256);
+
+      writer.writeBytes(len, bytes);
+    }
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    for (var cursor = lowerLimit; reader.nextField(); cursor *= 1.1) {
+      var len = Math.round(cursor);
+      if (len != reader.getFieldNumber()) throw 'fail!';
+
+      var bytes = reader.readBytes();
+      if (len != bytes.length) throw 'fail!';
+      for (var i = 0; i < bytes.length; i++) {
+        if (i % 256 != bytes[i]) throw 'fail!';
+      }
+    }
+  });
+
+
+  /**
+   * Tests nested messages.
+   */
+  it('testNesting', function() {
+    var writer = new jspb.BinaryWriter();
+  var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+
+    writer.writeInt32(1, 100);
+
+    // Add one message with 3 int fields.
+    writer.writeMessage(2, dummyMessage, function() {
+      writer.writeInt32(3, 300);
+      writer.writeInt32(4, 400);
+      writer.writeInt32(5, 500);
+    });
+
+    // Add one empty message.
+    writer.writeMessage(6, dummyMessage, goog.nullFunction);
+
+    writer.writeInt32(7, 700);
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    // Validate outermost message.
+
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(100, reader.readInt32());
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    reader.readMessage(dummyMessage, function() {
+      // Validate embedded message 1.
+      reader.nextField();
+      assertEquals(3, reader.getFieldNumber());
+      assertEquals(300, reader.readInt32());
+
+      reader.nextField();
+      assertEquals(4, reader.getFieldNumber());
+      assertEquals(400, reader.readInt32());
+
+      reader.nextField();
+      assertEquals(5, reader.getFieldNumber());
+      assertEquals(500, reader.readInt32());
+
+      assertEquals(false, reader.nextField());
+    });
+
+    reader.nextField();
+    assertEquals(6, reader.getFieldNumber());
+    reader.readMessage(dummyMessage, function() {
+      // Validate embedded message 2.
+
+      assertEquals(false, reader.nextField());
+    });
+
+    reader.nextField();
+    assertEquals(7, reader.getFieldNumber());
+    assertEquals(700, reader.readInt32());
+
+    assertEquals(false, reader.nextField());
+  });
+
+  /**
+   * Tests skipping fields of each type by interleaving them with sentinel
+   * values and skipping everything that's not a sentinel.
+   */
+  it('testSkipField', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var sentinel = 123456789;
+
+    // Write varint fields of different sizes.
+    writer.writeInt32(1, sentinel);
+    writer.writeInt32(1, 1);
+    writer.writeInt32(1, 1000);
+    writer.writeInt32(1, 1000000);
+    writer.writeInt32(1, 1000000000);
+
+    // Write fixed 64-bit encoded fields.
+    writer.writeInt32(2, sentinel);
+    writer.writeDouble(2, 1);
+    writer.writeFixed64(2, 1);
+    writer.writeSfixed64(2, 1);
+
+    // Write fixed 32-bit encoded fields.
+    writer.writeInt32(3, sentinel);
+    writer.writeFloat(3, 1);
+    writer.writeFixed32(3, 1);
+    writer.writeSfixed32(3, 1);
+
+    // Write delimited fields.
+    writer.writeInt32(4, sentinel);
+    writer.writeBytes(4, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+    writer.writeString(4, 'The quick brown fox jumps over the lazy dog');
+
+    // Write a group with a nested group inside. We use the internal
+    // .rawWriteVarint() to ensure the tested wire data is what we want,
+    // independently of any serialization logic.
+    writer.writeInt32(5, sentinel);
+    // Start group, field 5.
+    writer.rawWriteVarint(
+        (5 << 3) + jspb.BinaryConstants.WireType.START_GROUP);
+    // Varint, field 42.
+    writer.rawWriteVarint(
+        (42 << 3) + jspb.BinaryConstants.WireType.VARINT);
+    // Varint data.
+    writer.rawWriteVarint(42);
+    // Start group, field 6.
+    writer.rawWriteVarint(
+        (6 << 3) + jspb.BinaryConstants.WireType.START_GROUP);
+    // Varint, field 84.
+    writer.rawWriteVarint(
+        (84 << 3) + jspb.BinaryConstants.WireType.VARINT);
+    writer.rawWriteVarint(42);
+    // End group, field 6.
+    writer.rawWriteVarint(
+        (6 << 3) + jspb.BinaryConstants.WireType.END_GROUP);
+    // End group, field 5.
+    writer.rawWriteVarint(
+        (5 << 3) + jspb.BinaryConstants.WireType.END_GROUP);
+
+    // Write final sentinel.
+    writer.writeInt32(6, sentinel);
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    function skip(field, count) {
+      for (var i = 0; i < count; i++) {
+        reader.nextField();
+        if (field != reader.getFieldNumber()) throw 'fail!';
+        reader.skipField();
+      }
+    }
+
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+    skip(1, 4);
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+    skip(2, 3);
+
+    reader.nextField();
+    assertEquals(3, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+    skip(3, 3);
+
+    reader.nextField();
+    assertEquals(4, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+    skip(4, 2);
+
+    reader.nextField();
+    assertEquals(5, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+    skip(5, 1);
+
+    reader.nextField();
+    assertEquals(6, reader.getFieldNumber());
+    assertEquals(sentinel, reader.readInt32());
+  });
+
+
+  /**
+   * Tests packed fields.
+   */
+  it('testPackedFields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var sentinel = 123456789;
+
+    var unsignedData = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+    var signedData = [-1, 2, -3, 4, -5, 6, -7, 8, -9, 10];
+    var floatData = [1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9, 10.10];
+    var doubleData = [1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9, 10.10];
+    var boolData = [true, false, true, true, false, false, true, false];
+
+    for (var i = 0; i < floatData.length; i++) {
+      floatData[i] = truncate(floatData[i]);
+    }
+
+    writer.writeInt32(1, sentinel);
+
+    writer.writePackedInt32(2, signedData);
+    writer.writePackedInt64(2, signedData);
+    writer.writePackedUint32(2, unsignedData);
+    writer.writePackedUint64(2, unsignedData);
+    writer.writePackedSint32(2, signedData);
+    writer.writePackedSint64(2, signedData);
+    writer.writePackedFixed32(2, unsignedData);
+    writer.writePackedFixed64(2, unsignedData);
+    writer.writePackedSfixed32(2, signedData);
+    writer.writePackedSfixed64(2, signedData);
+    writer.writePackedFloat(2, floatData);
+    writer.writePackedDouble(2, doubleData);
+    writer.writePackedBool(2, boolData);
+    writer.writePackedEnum(2, unsignedData);
+
+    writer.writeInt32(3, sentinel);
+
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    reader.nextField();
+    assertEquals(sentinel, reader.readInt32());
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedInt32(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedInt64(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedUint32(), unsignedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedUint64(), unsignedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedSint32(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedSint64(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedFixed32(), unsignedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedFixed64(), unsignedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedSfixed32(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedSfixed64(), signedData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedFloat(), floatData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedDouble(), doubleData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedBool(), boolData);
+
+    reader.nextField();
+    assertElementsEquals(reader.readPackedEnum(), unsignedData);
+
+    reader.nextField();
+    assertEquals(sentinel, reader.readInt32());
+  });
+
+
+  /**
+   * Byte blobs inside nested messages should always have their byte offset set
+   * relative to the start of the outermost blob, not the start of their parent
+   * blob.
+   */
+  it('testNestedBlobs', function() {
+    // Create a proto consisting of two nested messages, with the inner one
+    // containing a blob of bytes.
+
+    var fieldTag = (1 << 3) | jspb.BinaryConstants.WireType.DELIMITED;
+    var blob = [1, 2, 3, 4, 5];
+    var writer = new jspb.BinaryWriter();
+    var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+
+    writer.writeMessage(1, dummyMessage, function() {
+      writer.writeMessage(1, dummyMessage, function() {
+        writer.writeBytes(1, blob);
+      });
+    });
+
+    // Peel off the outer two message layers. Each layer should have two bytes
+    // of overhead, one for the field tag and one for the length of the inner
+    // blob.
+
+    var decoder1 = new jspb.BinaryDecoder(writer.getResultBuffer());
+    assertEquals(fieldTag, decoder1.readUnsignedVarint32());
+    assertEquals(blob.length + 4, decoder1.readUnsignedVarint32());
+
+    var decoder2 = new jspb.BinaryDecoder(decoder1.readBytes(blob.length + 4));
+    assertEquals(fieldTag, decoder2.readUnsignedVarint32());
+    assertEquals(blob.length + 2, decoder2.readUnsignedVarint32());
+
+    assertEquals(fieldTag, decoder2.readUnsignedVarint32());
+    assertEquals(blob.length, decoder2.readUnsignedVarint32());
+    var bytes = decoder2.readBytes(blob.length);
+
+    assertElementsEquals(bytes, blob);
+  });
+
+
+  /**
+   * Tests read callbacks.
+   */
+  it('testReadCallbacks', function() {
+    var writer = new jspb.BinaryWriter();
+    var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+
+    // Add an int, a submessage, and another int.
+    writer.writeInt32(1, 100);
+
+    writer.writeMessage(2, dummyMessage, function() {
+      writer.writeInt32(3, 300);
+      writer.writeInt32(4, 400);
+      writer.writeInt32(5, 500);
+    });
+
+    writer.writeInt32(7, 700);
+
+    // Create the reader and register a custom read callback.
+    var reader = jspb.BinaryReader.alloc(writer.getResultBuffer());
+
+    /**
+     * @param {!jspb.BinaryReader} reader
+     * @return {*}
+     */
+    function readCallback(reader) {
+      reader.nextField();
+      assertEquals(3, reader.getFieldNumber());
+      assertEquals(300, reader.readInt32());
+
+      reader.nextField();
+      assertEquals(4, reader.getFieldNumber());
+      assertEquals(400, reader.readInt32());
+
+      reader.nextField();
+      assertEquals(5, reader.getFieldNumber());
+      assertEquals(500, reader.readInt32());
+
+      assertEquals(false, reader.nextField());
+    };
+
+    reader.registerReadCallback('readCallback', readCallback);
+
+    // Read the container message.
+    reader.nextField();
+    assertEquals(1, reader.getFieldNumber());
+    assertEquals(100, reader.readInt32());
+
+    reader.nextField();
+    assertEquals(2, reader.getFieldNumber());
+    reader.readMessage(dummyMessage, function() {
+      // Decode the embedded message using the registered callback.
+      reader.runReadCallback('readCallback');
+    });
+
+    reader.nextField();
+    assertEquals(7, reader.getFieldNumber());
+    assertEquals(700, reader.readInt32());
+
+    assertEquals(false, reader.nextField());
+  });
+});
diff --git a/js/binary/utils.js b/js/binary/utils.js
new file mode 100644
index 00000000..92600389
--- /dev/null
+++ b/js/binary/utils.js
@@ -0,0 +1,979 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains helper code used by jspb.BinaryReader
+ * and BinaryWriter.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.utils');
+
+goog.require('goog.asserts');
+goog.require('goog.crypt.base64');
+goog.require('goog.string');
+goog.require('jspb.BinaryConstants');
+
+
+/**
+ * Javascript can't natively handle 64-bit data types, so to manipulate them we
+ * have to split them into two 32-bit halves and do the math manually.
+ *
+ * Instead of instantiating and passing small structures around to do this, we
+ * instead just use two global temporary values. This one stores the low 32
+ * bits of a split value - for example, if the original value was a 64-bit
+ * integer, this temporary value will contain the low 32 bits of that integer.
+ * If the original value was a double, this temporary value will contain the
+ * low 32 bits of the binary representation of that double, etcetera.
+ * @type {number}
+ */
+jspb.utils.split64Low = 0;
+
+
+/**
+ * And correspondingly, this temporary variable will contain the high 32 bits
+ * of whatever value was split.
+ * @type {number}
+ */
+jspb.utils.split64High = 0;
+
+
+/**
+ * Splits an unsigned Javascript integer into two 32-bit halves and stores it
+ * in the temp values above.
+ * @param {number} value The number to split.
+ */
+jspb.utils.splitUint64 = function(value) {
+  // Extract low 32 bits and high 32 bits as unsigned integers.
+  var lowBits = value >>> 0;
+  var highBits = Math.floor((value - lowBits) /
+                            jspb.BinaryConstants.TWO_TO_32) >>> 0;
+
+  jspb.utils.split64Low = lowBits;
+  jspb.utils.split64High = highBits;
+};
+
+
+/**
+ * Splits a signed Javascript integer into two 32-bit halves and stores it in
+ * the temp values above.
+ * @param {number} value The number to split.
+ */
+jspb.utils.splitInt64 = function(value) {
+  // Convert to sign-magnitude representation.
+  var sign = (value < 0);
+  value = Math.abs(value);
+
+  // Extract low 32 bits and high 32 bits as unsigned integers.
+  var lowBits = value >>> 0;
+  var highBits = Math.floor((value - lowBits) /
+                            jspb.BinaryConstants.TWO_TO_32);
+  highBits = highBits >>> 0;
+
+  // Perform two's complement conversion if the sign bit was set.
+  if (sign) {
+    highBits = ~highBits >>> 0;
+    lowBits = ~lowBits >>> 0;
+    lowBits += 1;
+    if (lowBits > 0xFFFFFFFF) {
+      lowBits = 0;
+      highBits++;
+      if (highBits > 0xFFFFFFFF) highBits = 0;
+    }
+  }
+
+  jspb.utils.split64Low = lowBits;
+  jspb.utils.split64High = highBits;
+};
+
+
+/**
+ * Convers a signed Javascript integer into zigzag format, splits it into two
+ * 32-bit halves, and stores it in the temp values above.
+ * @param {number} value The number to split.
+ */
+jspb.utils.splitZigzag64 = function(value) {
+  // Convert to sign-magnitude and scale by 2 before we split the value.
+  var sign = (value < 0);
+  value = Math.abs(value) * 2;
+
+  jspb.utils.splitUint64(value);
+  var lowBits = jspb.utils.split64Low;
+  var highBits = jspb.utils.split64High;
+
+  // If the value is negative, subtract 1 from the split representation so we
+  // don't lose the sign bit due to precision issues.
+  if (sign) {
+    if (lowBits == 0) {
+      if (highBits == 0) {
+        lowBits = 0xFFFFFFFF;
+        highBits = 0xFFFFFFFF;
+      } else {
+        highBits--;
+        lowBits = 0xFFFFFFFF;
+      }
+    } else {
+      lowBits--;
+    }
+  }
+
+  jspb.utils.split64Low = lowBits;
+  jspb.utils.split64High = highBits;
+};
+
+
+/**
+ * Converts a floating-point number into 32-bit IEEE representation and stores
+ * it in the temp values above.
+ * @param {number} value
+ */
+jspb.utils.splitFloat32 = function(value) {
+  var sign = (value < 0) ? 1 : 0;
+  value = sign ? -value : value;
+  var exp;
+  var mant;
+
+  // Handle zeros.
+  if (value === 0) {
+    if ((1 / value) > 0) {
+      // Positive zero.
+      jspb.utils.split64High = 0;
+      jspb.utils.split64Low = 0x00000000;
+    } else {
+      // Negative zero.
+      jspb.utils.split64High = 0;
+      jspb.utils.split64Low = 0x80000000;
+    }
+    return;
+  }
+
+  // Handle nans.
+  if (isNaN(value)) {
+    jspb.utils.split64High = 0;
+    jspb.utils.split64Low = 0x7FFFFFFF;
+    return;
+  }
+
+  // Handle infinities.
+  if (value > jspb.BinaryConstants.FLOAT32_MAX) {
+    jspb.utils.split64High = 0;
+    jspb.utils.split64Low = ((sign << 31) | (0x7F800000)) >>> 0;
+    return;
+  }
+
+  // Handle denormals.
+  if (value < jspb.BinaryConstants.FLOAT32_MIN) {
+    // Number is a denormal.
+    mant = Math.round(value / Math.pow(2, -149));
+    jspb.utils.split64High = 0;
+    jspb.utils.split64Low = ((sign << 31) | mant) >>> 0;
+    return;
+  }
+
+  exp = Math.floor(Math.log(value) / Math.LN2);
+  mant = value * Math.pow(2, -exp);
+  mant = Math.round(mant * jspb.BinaryConstants.TWO_TO_23) & 0x7FFFFF;
+
+  jspb.utils.split64High = 0;
+  jspb.utils.split64Low = ((sign << 31) | ((exp + 127) << 23) | mant) >>> 0;
+};
+
+
+/**
+ * Converts a floating-point number into 64-bit IEEE representation and stores
+ * it in the temp values above.
+ * @param {number} value
+ */
+jspb.utils.splitFloat64 = function(value) {
+  var sign = (value < 0) ? 1 : 0;
+  value = sign ? -value : value;
+
+  // Handle zeros.
+  if (value === 0) {
+    if ((1 / value) > 0) {
+      // Positive zero.
+      jspb.utils.split64High = 0x00000000;
+      jspb.utils.split64Low = 0x00000000;
+    } else {
+      // Negative zero.
+      jspb.utils.split64High = 0x80000000;
+      jspb.utils.split64Low = 0x00000000;
+    }
+    return;
+  }
+
+  // Handle nans.
+  if (isNaN(value)) {
+    jspb.utils.split64High = 0x7FFFFFFF;
+    jspb.utils.split64Low = 0xFFFFFFFF;
+    return;
+  }
+
+  // Handle infinities.
+  if (value > jspb.BinaryConstants.FLOAT64_MAX) {
+    jspb.utils.split64High = ((sign << 31) | (0x7FF00000)) >>> 0;
+    jspb.utils.split64Low = 0;
+    return;
+  }
+
+  // Handle denormals.
+  if (value < jspb.BinaryConstants.FLOAT64_MIN) {
+    // Number is a denormal.
+    var mant = value / Math.pow(2, -1074);
+    var mantHigh = (mant / jspb.BinaryConstants.TWO_TO_32);
+    jspb.utils.split64High = ((sign << 31) | mantHigh) >>> 0;
+    jspb.utils.split64Low = (mant >>> 0);
+    return;
+  }
+
+  var exp = Math.floor(Math.log(value) / Math.LN2);
+  if (exp == 1024) exp = 1023;
+  var mant = value * Math.pow(2, -exp);
+
+  var mantHigh = (mant * jspb.BinaryConstants.TWO_TO_20) & 0xFFFFF;
+  var mantLow = (mant * jspb.BinaryConstants.TWO_TO_52) >>> 0;
+
+  jspb.utils.split64High =
+      ((sign << 31) | ((exp + 1023) << 20) | mantHigh) >>> 0;
+  jspb.utils.split64Low = mantLow;
+};
+
+
+/**
+ * Converts an 8-character hash string into two 32-bit numbers and stores them
+ * in the temp values above.
+ * @param {string} hash
+ */
+jspb.utils.splitHash64 = function(hash) {
+  var a = hash.charCodeAt(0);
+  var b = hash.charCodeAt(1);
+  var c = hash.charCodeAt(2);
+  var d = hash.charCodeAt(3);
+  var e = hash.charCodeAt(4);
+  var f = hash.charCodeAt(5);
+  var g = hash.charCodeAt(6);
+  var h = hash.charCodeAt(7);
+
+  jspb.utils.split64Low = (a + (b << 8) + (c << 16) + (d << 24)) >>> 0;
+  jspb.utils.split64High = (e + (f << 8) + (g << 16) + (h << 24)) >>> 0;
+};
+
+
+/**
+ * Joins two 32-bit values into a 64-bit unsigned integer. Precision will be
+ * lost if the result is greater than 2^52.
+ * @param {number} bitsLow
+ * @param {number} bitsHigh
+ * @return {number}
+ */
+jspb.utils.joinUint64 = function(bitsLow, bitsHigh) {
+  return bitsHigh * jspb.BinaryConstants.TWO_TO_32 + bitsLow;
+};
+
+
+/**
+ * Joins two 32-bit values into a 64-bit signed integer. Precision will be lost
+ * if the result is greater than 2^52.
+ * @param {number} bitsLow
+ * @param {number} bitsHigh
+ * @return {number}
+ */
+jspb.utils.joinInt64 = function(bitsLow, bitsHigh) {
+  // If the high bit is set, do a manual two's complement conversion.
+  var sign = (bitsHigh & 0x80000000);
+  if (sign) {
+    bitsLow = (~bitsLow + 1) >>> 0;
+    bitsHigh = ~bitsHigh >>> 0;
+    if (bitsLow == 0) {
+      bitsHigh = (bitsHigh + 1) >>> 0;
+    }
+  }
+
+  var result = jspb.utils.joinUint64(bitsLow, bitsHigh);
+  return sign ? -result : result;
+};
+
+
+/**
+ * Joins two 32-bit values into a 64-bit unsigned integer and applies zigzag
+ * decoding. Precision will be lost if the result is greater than 2^52.
+ * @param {number} bitsLow
+ * @param {number} bitsHigh
+ * @return {number}
+ */
+jspb.utils.joinZigzag64 = function(bitsLow, bitsHigh) {
+  // Extract the sign bit and shift right by one.
+  var sign = bitsLow & 1;
+  bitsLow = ((bitsLow >>> 1) | (bitsHigh << 31)) >>> 0;
+  bitsHigh = bitsHigh >>> 1;
+
+  // Increment the split value if the sign bit was set.
+  if (sign) {
+    bitsLow = (bitsLow + 1) >>> 0;
+    if (bitsLow == 0) {
+      bitsHigh = (bitsHigh + 1) >>> 0;
+    }
+  }
+
+  var result = jspb.utils.joinUint64(bitsLow, bitsHigh);
+  return sign ? -result : result;
+};
+
+
+/**
+ * Joins two 32-bit values into a 32-bit IEEE floating point number and
+ * converts it back into a Javascript number.
+ * @param {number} bitsLow The low 32 bits of the binary number;
+ * @param {number} bitsHigh The high 32 bits of the binary number.
+ * @return {number}
+ */
+jspb.utils.joinFloat32 = function(bitsLow, bitsHigh) {
+  var sign = ((bitsLow >> 31) * 2 + 1);
+  var exp = (bitsLow >>> 23) & 0xFF;
+  var mant = bitsLow & 0x7FFFFF;
+
+  if (exp == 0xFF) {
+    if (mant) {
+      return NaN;
+    } else {
+      return sign * Infinity;
+    }
+  }
+
+  if (exp == 0) {
+    // Denormal.
+    return sign * Math.pow(2, -149) * mant;
+  } else {
+    return sign * Math.pow(2, exp - 150) *
+           (mant + Math.pow(2, 23));
+  }
+};
+
+
+/**
+ * Joins two 32-bit values into a 64-bit IEEE floating point number and
+ * converts it back into a Javascript number.
+ * @param {number} bitsLow The low 32 bits of the binary number;
+ * @param {number} bitsHigh The high 32 bits of the binary number.
+ * @return {number}
+ */
+jspb.utils.joinFloat64 = function(bitsLow, bitsHigh) {
+  var sign = ((bitsHigh >> 31) * 2 + 1);
+  var exp = (bitsHigh >>> 20) & 0x7FF;
+  var mant = jspb.BinaryConstants.TWO_TO_32 * (bitsHigh & 0xFFFFF) + bitsLow;
+
+  if (exp == 0x7FF) {
+    if (mant) {
+      return NaN;
+    } else {
+      return sign * Infinity;
+    }
+  }
+
+  if (exp == 0) {
+    // Denormal.
+    return sign * Math.pow(2, -1074) * mant;
+  } else {
+    return sign * Math.pow(2, exp - 1075) *
+           (mant + jspb.BinaryConstants.TWO_TO_52);
+  }
+};
+
+
+/**
+ * Joins two 32-bit values into an 8-character hash string.
+ * @param {number} bitsLow
+ * @param {number} bitsHigh
+ * @return {string}
+ */
+jspb.utils.joinHash64 = function(bitsLow, bitsHigh) {
+  var a = (bitsLow >>> 0) & 0xFF;
+  var b = (bitsLow >>> 8) & 0xFF;
+  var c = (bitsLow >>> 16) & 0xFF;
+  var d = (bitsLow >>> 24) & 0xFF;
+  var e = (bitsHigh >>> 0) & 0xFF;
+  var f = (bitsHigh >>> 8) & 0xFF;
+  var g = (bitsHigh >>> 16) & 0xFF;
+  var h = (bitsHigh >>> 24) & 0xFF;
+
+  return String.fromCharCode(a, b, c, d, e, f, g, h);
+};
+
+
+/**
+ * Individual digits for number->string conversion.
+ * @const {!Array.<number>}
+ */
+jspb.utils.DIGITS = [
+  '0', '1', '2', '3', '4', '5', '6', '7',
+  '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+];
+
+
+/**
+ * Losslessly converts a 64-bit unsigned integer in 32:32 split representation
+ * into a decimal string.
+ * @param {number} bitsLow The low 32 bits of the binary number;
+ * @param {number} bitsHigh The high 32 bits of the binary number.
+ * @return {string} The binary number represented as a string.
+ */
+jspb.utils.joinUnsignedDecimalString = function(bitsLow, bitsHigh) {
+  // Skip the expensive conversion if the number is small enough to use the
+  // built-in conversions.
+  if (bitsHigh <= 0x1FFFFF) {
+    return '' + (jspb.BinaryConstants.TWO_TO_32 * bitsHigh + bitsLow);
+  }
+
+  // What this code is doing is essentially converting the input number from
+  // base-2 to base-1e7, which allows us to represent the 64-bit range with
+  // only 3 (very large) digits. Those digits are then trivial to convert to
+  // a base-10 string.
+
+  // The magic numbers used here are -
+  // 2^24 = 16777216 = (1,6777216) in base-1e7.
+  // 2^48 = 281474976710656 = (2,8147497,6710656) in base-1e7.
+
+  // Split 32:32 representation into 16:24:24 representation so our
+  // intermediate digits don't overflow.
+  var low = bitsLow & 0xFFFFFF;
+  var mid = (((bitsLow >>> 24) | (bitsHigh << 8)) >>> 0) & 0xFFFFFF;
+  var high = (bitsHigh >> 16) & 0xFFFF;
+
+  // Assemble our three base-1e7 digits, ignoring carries. The maximum
+  // value in a digit at this step is representable as a 48-bit integer, which
+  // can be stored in a 64-bit floating point number.
+  var digitA = low + (mid * 6777216) + (high * 6710656);
+  var digitB = mid + (high * 8147497);
+  var digitC = (high * 2);
+
+  // Apply carries from A to B and from B to C.
+  var base = 10000000;
+  if (digitA >= base) {
+    digitB += Math.floor(digitA / base);
+    digitA %= base;
+  }
+
+  if (digitB >= base) {
+    digitC += Math.floor(digitB / base);
+    digitB %= base;
+  }
+
+  // Convert base-1e7 digits to base-10, omitting leading zeroes.
+  var table = jspb.utils.DIGITS;
+  var start = false;
+  var result = '';
+
+  function emit(digit) {
+    var temp = base;
+    for (var i = 0; i < 7; i++) {
+      temp /= 10;
+      var decimalDigit = ((digit / temp) % 10) >>> 0;
+      if ((decimalDigit == 0) && !start) continue;
+      start = true;
+      result += table[decimalDigit];
+    }
+  }
+
+  if (digitC || start) emit(digitC);
+  if (digitB || start) emit(digitB);
+  if (digitA || start) emit(digitA);
+
+  return result;
+};
+
+
+/**
+ * Losslessly converts a 64-bit signed integer in 32:32 split representation
+ * into a decimal string.
+ * @param {number} bitsLow The low 32 bits of the binary number;
+ * @param {number} bitsHigh The high 32 bits of the binary number.
+ * @return {string} The binary number represented as a string.
+ */
+jspb.utils.joinSignedDecimalString = function(bitsLow, bitsHigh) {
+  // If we're treating the input as a signed value and the high bit is set, do
+  // a manual two's complement conversion before the decimal conversion.
+  var negative = (bitsHigh & 0x80000000);
+  if (negative) {
+    bitsLow = (~bitsLow + 1) >>> 0;
+    var carry = (bitsLow == 0) ? 1 : 0;
+    bitsHigh = (~bitsHigh + carry) >>> 0;
+  }
+
+  var result = jspb.utils.joinUnsignedDecimalString(bitsLow, bitsHigh);
+  return negative ? '-' + result : result;
+};
+
+
+/**
+ * Convert an 8-character hash string representing either a signed or unsigned
+ * 64-bit integer into its decimal representation without losing accuracy.
+ * @param {string} hash The hash string to convert.
+ * @param {boolean} signed True if we should treat the hash string as encoding
+ *     a signed integer.
+ * @return {string}
+ */
+jspb.utils.hash64ToDecimalString = function(hash, signed) {
+  jspb.utils.splitHash64(hash);
+  var bitsLow = jspb.utils.split64Low;
+  var bitsHigh = jspb.utils.split64High;
+  return signed ?
+      jspb.utils.joinSignedDecimalString(bitsLow, bitsHigh) :
+      jspb.utils.joinUnsignedDecimalString(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Converts an array of 8-character hash strings into their decimal
+ * representations.
+ * @param {!Array.<string>} hashes The array of hash strings to convert.
+ * @param {boolean} signed True if we should treat the hash string as encoding
+ *     a signed integer.
+ * @return {!Array.<string>}
+ */
+jspb.utils.hash64ArrayToDecimalStrings = function(hashes, signed) {
+  var result = new Array(hashes.length);
+  for (var i = 0; i < hashes.length; i++) {
+    result[i] = jspb.utils.hash64ToDecimalString(hashes[i], signed);
+  }
+  return result;
+};
+
+
+/**
+ * Converts an 8-character hash string into its hexadecimal representation.
+ * @param {string} hash
+ * @return {string}
+ */
+jspb.utils.hash64ToHexString = function(hash) {
+  var temp = new Array(18);
+  temp[0] = '0';
+  temp[1] = 'x';
+
+  for (var i = 0; i < 8; i++) {
+    var c = hash.charCodeAt(7 - i);
+    temp[i * 2 + 2] = jspb.utils.DIGITS[c >> 4];
+    temp[i * 2 + 3] = jspb.utils.DIGITS[c & 0xF];
+  }
+
+  var result = temp.join('');
+  return result;
+};
+
+
+/**
+ * Converts a '0x<16 digits>' hex string into its hash string representation.
+ * @param {string} hex
+ * @return {string}
+ */
+jspb.utils.hexStringToHash64 = function(hex) {
+  hex = hex.toLowerCase();
+  goog.asserts.assert(hex.length == 18);
+  goog.asserts.assert(hex[0] == '0');
+  goog.asserts.assert(hex[1] == 'x');
+
+  var result = '';
+  for (var i = 0; i < 8; i++) {
+    var hi = jspb.utils.DIGITS.indexOf(hex[i * 2 + 2]);
+    var lo = jspb.utils.DIGITS.indexOf(hex[i * 2 + 3]);
+    result = String.fromCharCode(hi * 16 + lo) + result;
+  }
+
+  return result;
+};
+
+
+/**
+ * Convert an 8-character hash string representing either a signed or unsigned
+ * 64-bit integer into a Javascript number. Will lose accuracy if the result is
+ * larger than 2^52.
+ * @param {string} hash The hash string to convert.
+ * @param {boolean} signed True if the has should be interpreted as a signed
+ *     number.
+ * @return {number}
+ */
+jspb.utils.hash64ToNumber = function(hash, signed) {
+  jspb.utils.splitHash64(hash);
+  var bitsLow = jspb.utils.split64Low;
+  var bitsHigh = jspb.utils.split64High;
+  return signed ? jspb.utils.joinInt64(bitsLow, bitsHigh) :
+                  jspb.utils.joinUint64(bitsLow, bitsHigh);
+};
+
+
+/**
+ * Convert a Javascript number into an 8-character hash string. Will lose
+ * precision if the value is non-integral or greater than 2^64.
+ * @param {number} value The integer to convert.
+ * @return {string}
+ */
+jspb.utils.numberToHash64 = function(value) {
+  jspb.utils.splitInt64(value);
+  return jspb.utils.joinHash64(jspb.utils.split64Low,
+                                  jspb.utils.split64High);
+};
+
+
+/**
+ * Counts the number of contiguous varints in a buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @return {number} The number of varints in the buffer.
+ */
+jspb.utils.countVarints = function(buffer, start, end) {
+  // Count how many high bits of each byte were set in the buffer.
+  var count = 0;
+  for (var i = start; i < end; i++) {
+    count += buffer[i] >> 7;
+  }
+
+  // The number of varints in the buffer equals the size of the buffer minus
+  // the number of non-terminal bytes in the buffer (those with the high bit
+  // set).
+  return (end - start) - count;
+};
+
+
+/**
+ * Counts the number of contiguous varint fields with the given field number in
+ * the buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @param {number} field The field number to count.
+ * @return {number} The number of matching fields in the buffer.
+ */
+jspb.utils.countVarintFields = function(buffer, start, end, field) {
+  var count = 0;
+  var cursor = start;
+  var tag = field * 8 + jspb.BinaryConstants.WireType.VARINT;
+
+  if (tag < 128) {
+    // Single-byte field tag, we can use a slightly quicker count.
+    while (cursor < end) {
+      // Skip the field tag, or exit if we find a non-matching tag.
+      if (buffer[cursor++] != tag) return count;
+
+      // Field tag matches, we've found a valid field.
+      count++;
+
+      // Skip the varint.
+      while (1) {
+        var x = buffer[cursor++];
+        if ((x & 0x80) == 0) break;
+      }
+    }
+  } else {
+    while (cursor < end) {
+      // Skip the field tag, or exit if we find a non-matching tag.
+      var temp = tag;
+      while (temp > 128) {
+        if (buffer[cursor] != ((temp & 0x7F) | 0x80)) return count;
+        cursor++;
+        temp >>= 7;
+      }
+      if (buffer[cursor++] != temp) return count;
+
+      // Field tag matches, we've found a valid field.
+      count++;
+
+      // Skip the varint.
+      while (1) {
+        var x = buffer[cursor++];
+        if ((x & 0x80) == 0) break;
+      }
+    }
+  }
+  return count;
+};
+
+
+/**
+ * Counts the number of contiguous fixed32 fields with the given tag in the
+ * buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @param {number} tag The tag value to count.
+ * @param {number} stride The number of bytes to skip per field.
+ * @return {number} The number of fields with a matching tag in the buffer.
+ * @private
+ */
+jspb.utils.countFixedFields_ =
+    function(buffer, start, end, tag, stride) {
+  var count = 0;
+  var cursor = start;
+
+  if (tag < 128) {
+    // Single-byte field tag, we can use a slightly quicker count.
+    while (cursor < end) {
+      // Skip the field tag, or exit if we find a non-matching tag.
+      if (buffer[cursor++] != tag) return count;
+
+      // Field tag matches, we've found a valid field.
+      count++;
+
+      // Skip the value.
+      cursor += stride;
+    }
+  } else {
+    while (cursor < end) {
+      // Skip the field tag, or exit if we find a non-matching tag.
+      var temp = tag;
+      while (temp > 128) {
+        if (buffer[cursor++] != ((temp & 0x7F) | 0x80)) return count;
+        temp >>= 7;
+      }
+      if (buffer[cursor++] != temp) return count;
+
+      // Field tag matches, we've found a valid field.
+      count++;
+
+      // Skip the value.
+      cursor += stride;
+    }
+  }
+  return count;
+};
+
+
+/**
+ * Counts the number of contiguous fixed32 fields with the given field number
+ * in the buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @param {number} field The field number to count.
+ * @return {number} The number of matching fields in the buffer.
+ */
+jspb.utils.countFixed32Fields = function(buffer, start, end, field) {
+  var tag = field * 8 + jspb.BinaryConstants.WireType.FIXED32;
+  return jspb.utils.countFixedFields_(buffer, start, end, tag, 4);
+};
+
+
+/**
+ * Counts the number of contiguous fixed64 fields with the given field number
+ * in the buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @param {number} field The field number to count
+ * @return {number} The number of matching fields in the buffer.
+ */
+jspb.utils.countFixed64Fields = function(buffer, start, end, field) {
+  var tag = field * 8 + jspb.BinaryConstants.WireType.FIXED64;
+  return jspb.utils.countFixedFields_(buffer, start, end, tag, 8);
+};
+
+
+/**
+ * Counts the number of contiguous delimited fields with the given field number
+ * in the buffer.
+ * @param {!Uint8Array} buffer The buffer to scan.
+ * @param {number} start The starting point in the buffer to scan.
+ * @param {number} end The end point in the buffer to scan.
+ * @param {number} field The field number to count.
+ * @return {number} The number of matching fields in the buffer.
+ */
+jspb.utils.countDelimitedFields = function(buffer, start, end, field) {
+  var count = 0;
+  var cursor = start;
+  var tag = field * 8 + jspb.BinaryConstants.WireType.DELIMITED;
+
+  while (cursor < end) {
+    // Skip the field tag, or exit if we find a non-matching tag.
+    var temp = tag;
+    while (temp > 128) {
+      if (buffer[cursor++] != ((temp & 0x7F) | 0x80)) return count;
+      temp >>= 7;
+    }
+    if (buffer[cursor++] != temp) return count;
+
+    // Field tag matches, we've found a valid field.
+    count++;
+
+    // Decode the length prefix.
+    var length = 0;
+    var shift = 1;
+    while (1) {
+      temp = buffer[cursor++];
+      length += (temp & 0x7f) * shift;
+      shift *= 128;
+      if ((temp & 0x80) == 0) break;
+    }
+
+    // Advance the cursor past the blob.
+    cursor += length;
+  }
+  return count;
+};
+
+
+/**
+ * Clones a scalar field. Pulling this out to a helper method saves us a few
+ * bytes of generated code.
+ * @param {Array} array
+ * @return {Array}
+ */
+jspb.utils.cloneRepeatedScalarField = function(array) {
+  return array ? array.slice() : null;
+};
+
+
+/**
+ * Clones an array of messages using the provided cloner function.
+ * @param {Array.<jspb.BinaryMessage>} messages
+ * @param {jspb.ClonerFunction} cloner
+ * @return {Array.<jspb.BinaryMessage>}
+ */
+jspb.utils.cloneRepeatedMessageField = function(messages, cloner) {
+  if (messages === null) return null;
+  var result = [];
+  for (var i = 0; i < messages.length; i++) {
+    result.push(cloner(messages[i]));
+  }
+  return result;
+};
+
+
+/**
+ * Clones an array of byte blobs.
+ * @param {Array.<Uint8Array>} blobs
+ * @return {Array.<Uint8Array>}
+ */
+jspb.utils.cloneRepeatedBlobField = function(blobs) {
+  if (blobs === null) return null;
+  var result = [];
+  for (var i = 0; i < blobs.length; i++) {
+    result.push(new Uint8Array(blobs[i]));
+  }
+  return result;
+};
+
+
+/**
+ * String-ify bytes for text format. Should be optimized away in non-debug.
+ * The returned string uses \xXX escapes for all values and is itself quoted.
+ * [1, 31] serializes to '"\x01\x1f"'.
+ * @param {jspb.ByteSource} byteSource The bytes to serialize.
+ * @param {boolean=} opt_stringIsRawBytes The string is interpreted as a series
+ * of raw bytes rather than base64 data.
+ * @return {string} Stringified bytes for text format.
+ */
+jspb.utils.debugBytesToTextFormat = function(byteSource,
+                                                opt_stringIsRawBytes) {
+  var s = '"';
+  if (byteSource) {
+    var bytes =
+        jspb.utils.byteSourceToUint8Array(byteSource, opt_stringIsRawBytes);
+    for (var i = 0; i < bytes.length; i++) {
+      s += '\\x';
+      if (bytes[i] < 16) s += '0';
+      s += bytes[i].toString(16);
+    }
+  }
+  return s + '"';
+};
+
+
+/**
+ * String-ify a scalar for text format. Should be optimized away in non-debug.
+ * @param {string|number|boolean} scalar The scalar to stringify.
+ * @return {string} Stringified scalar for text format.
+ */
+jspb.utils.debugScalarToTextFormat = function(scalar) {
+  if (goog.isString(scalar)) {
+    return goog.string.quote(scalar);
+  } else {
+    return scalar.toString();
+  }
+};
+
+
+/**
+ * Utility function: convert a string with codepoints 0--255 inclusive to a
+ * Uint8Array. If any codepoints greater than 255 exist in the string, throws an
+ * exception.
+ * @param {string} str
+ * @return {!Uint8Array}
+ * @private
+ */
+jspb.utils.stringToByteArray_ = function(str) {
+  var arr = new Uint8Array(str.length);
+  for (var i = 0; i < str.length; i++) {
+    var codepoint = str.charCodeAt(i);
+    if (codepoint > 255) {
+      throw new Error('Conversion error: string contains codepoint ' +
+                      'outside of byte range');
+    }
+    arr[i] = codepoint;
+  }
+  return arr;
+};
+
+
+/**
+ * Converts any type defined in jspb.ByteSource into a Uint8Array.
+ * @param {!jspb.ByteSource} data
+ * @param {boolean=} opt_stringIsRawBytes Interpret a string as a series of raw
+ * bytes (encoded as codepoints 0--255 inclusive) rather than base64 data
+ * (default behavior).
+ * @return {!Uint8Array}
+ * @suppress {invalidCasts}
+ */
+jspb.utils.byteSourceToUint8Array = function(data, opt_stringIsRawBytes) {
+  if (data.constructor === Uint8Array) {
+    return /** @type {!Uint8Array} */(data);
+  }
+
+  if (data.constructor === ArrayBuffer) {
+    data = /** @type {!ArrayBuffer} */(data);
+    return /** @type {!Uint8Array} */(new Uint8Array(data));
+  }
+
+  if (data.constructor === Array) {
+    data = /** @type {!Array.<number>} */(data);
+    return /** @type {!Uint8Array} */(new Uint8Array(data));
+  }
+
+  if (data.constructor === String) {
+    data = /** @type {string} */(data);
+    if (opt_stringIsRawBytes) {
+      return jspb.utils.stringToByteArray_(data);
+    } else {
+      return goog.crypt.base64.decodeStringToUint8Array(data);
+    }
+  }
+
+  goog.asserts.fail('Type not convertible to Uint8Array.');
+  return /** @type {!Uint8Array} */(new Uint8Array(0));
+};
diff --git a/js/binary/utils_test.js b/js/binary/utils_test.js
new file mode 100644
index 00000000..5c330791
--- /dev/null
+++ b/js/binary/utils_test.js
@@ -0,0 +1,632 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Test cases for jspb's helper functions.
+ *
+ * Test suite is written using Jasmine -- see http://jasmine.github.io/
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.require('goog.crypt.base64');
+goog.require('goog.testing.asserts');
+goog.require('jspb.BinaryConstants');
+goog.require('jspb.BinaryWriter');
+goog.require('jspb.utils');
+
+
+/**
+ * @param {number} x
+ * @return {number}
+ */
+function truncate(x) {
+  var temp = new Float32Array(1);
+  temp[0] = x;
+  return temp[0];
+}
+
+
+/**
+ * Converts an 64-bit integer in split representation to a 64-bit hash string
+ * (8 bits encoded per character).
+ * @param {number} bitsLow The low 32 bits of the split 64-bit integer.
+ * @param {number} bitsHigh The high 32 bits of the split 64-bit integer.
+ * @return {string} The encoded hash string, 8 bits per character.
+ */
+function toHashString(bitsLow, bitsHigh) {
+  return String.fromCharCode((bitsLow >>> 0) & 0xFF,
+                             (bitsLow >>> 8) & 0xFF,
+                             (bitsLow >>> 16) & 0xFF,
+                             (bitsLow >>> 24) & 0xFF,
+                             (bitsHigh >>> 0) & 0xFF,
+                             (bitsHigh >>> 8) & 0xFF,
+                             (bitsHigh >>> 16) & 0xFF,
+                             (bitsHigh >>> 24) & 0xFF);
+}
+
+
+describe('binaryUtilsTest', function() {
+  /**
+   * Tests lossless binary-to-decimal conversion.
+   */
+  it('testDecimalConversion', function() {
+    // Check some magic numbers.
+    var result =
+        jspb.utils.joinUnsignedDecimalString(0x89e80001, 0x8ac72304);
+    assertEquals('10000000000000000001', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0xacd05f15, 0x1b69b4b);
+    assertEquals('123456789123456789', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0xeb1f0ad2, 0xab54a98c);
+    assertEquals('12345678901234567890', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0xe3b70cb1, 0x891087b8);
+    assertEquals('9876543210987654321', result);
+
+    // Check limits.
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x00000000);
+    assertEquals('0', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0xFFFFFFFF, 0xFFFFFFFF);
+    assertEquals('18446744073709551615', result);
+
+    // Check each bit of the low dword.
+    for (var i = 0; i < 32; i++) {
+      var low = (1 << i) >>> 0;
+      result = jspb.utils.joinUnsignedDecimalString(low, 0);
+      assertEquals('' + Math.pow(2, i), result);
+    }
+
+    // Check the first 20 bits of the high dword.
+    for (var i = 0; i < 20; i++) {
+      var high = (1 << i) >>> 0;
+      result = jspb.utils.joinUnsignedDecimalString(0, high);
+      assertEquals('' + Math.pow(2, 32 + i), result);
+    }
+
+    // V8's internal double-to-string conversion is inaccurate for values above
+    // 2^52, even if they're representable integers - check the rest of the bits
+    // manually against the correct string representations of 2^N.
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x00100000);
+    assertEquals('4503599627370496', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x00200000);
+    assertEquals('9007199254740992', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x00400000);
+    assertEquals('18014398509481984', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x00800000);
+    assertEquals('36028797018963968', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x01000000);
+    assertEquals('72057594037927936', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x02000000);
+    assertEquals('144115188075855872', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x04000000);
+    assertEquals('288230376151711744', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x08000000);
+    assertEquals('576460752303423488', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x10000000);
+    assertEquals('1152921504606846976', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x20000000);
+    assertEquals('2305843009213693952', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x40000000);
+    assertEquals('4611686018427387904', result);
+
+    result = jspb.utils.joinUnsignedDecimalString(0x00000000, 0x80000000);
+    assertEquals('9223372036854775808', result);
+  });
+
+
+  /**
+   * Going from hash strings to decimal strings should also be lossless.
+   */
+  it('testHashToDecimalConversion', function() {
+    var result;
+    var convert = jspb.utils.hash64ToDecimalString;
+
+    result = convert(toHashString(0x00000000, 0x00000000), false);
+    assertEquals('0', result);
+
+    result = convert(toHashString(0x00000000, 0x00000000), true);
+    assertEquals('0', result);
+
+    result = convert(toHashString(0xFFFFFFFF, 0xFFFFFFFF), false);
+    assertEquals('18446744073709551615', result);
+
+    result = convert(toHashString(0xFFFFFFFF, 0xFFFFFFFF), true);
+    assertEquals('-1', result);
+
+    result = convert(toHashString(0x00000000, 0x80000000), false);
+    assertEquals('9223372036854775808', result);
+
+    result = convert(toHashString(0x00000000, 0x80000000), true);
+    assertEquals('-9223372036854775808', result);
+
+    result = convert(toHashString(0xacd05f15, 0x01b69b4b), false);
+    assertEquals('123456789123456789', result);
+
+    result = convert(toHashString(~0xacd05f15 + 1, ~0x01b69b4b), true);
+    assertEquals('-123456789123456789', result);
+
+    // And converting arrays of hashes should work the same way.
+    result = jspb.utils.hash64ArrayToDecimalStrings([
+      toHashString(0xFFFFFFFF, 0xFFFFFFFF),
+      toHashString(0x00000000, 0x80000000),
+      toHashString(0xacd05f15, 0x01b69b4b)], false);
+    assertEquals(3, result.length);
+    assertEquals('18446744073709551615', result[0]);
+    assertEquals('9223372036854775808', result[1]);
+    assertEquals('123456789123456789', result[2]);
+  });
+
+
+  /**
+   * Going from hash strings to hex strings should be lossless.
+   */
+  it('testHashToHexConversion', function() {
+    var result;
+    var convert = jspb.utils.hash64ToHexString;
+
+    result = convert(toHashString(0x00000000, 0x00000000));
+    assertEquals('0x0000000000000000', result);
+
+    result = convert(toHashString(0xFFFFFFFF, 0xFFFFFFFF));
+    assertEquals('0xffffffffffffffff', result);
+
+    result = convert(toHashString(0x12345678, 0x9ABCDEF0));
+    assertEquals('0x9abcdef012345678', result);
+  });
+
+
+  /**
+   * Going from hex strings to hash strings should be lossless.
+   */
+  it('testHexToHashConversion', function() {
+    var result;
+    var convert = jspb.utils.hexStringToHash64;
+
+    result = convert('0x0000000000000000');
+    assertEquals(String.fromCharCode.apply(null,
+        [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]), result);
+
+    result = convert('0xffffffffffffffff');
+    assertEquals(String.fromCharCode.apply(null,
+        [0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF]), result);
+
+    // Hex string is big-endian, hash string is little-endian.
+    result = convert('0x123456789ABCDEF0');
+    assertEquals(String.fromCharCode.apply(null,
+        [0xF0, 0xDE, 0xBC, 0x9A, 0x78, 0x56, 0x34, 0x12]), result);
+
+    // Capitalization should not matter.
+    result = convert('0x0000abcdefABCDEF');
+    assertEquals(String.fromCharCode.apply(null,
+        [0xEF, 0xCD, 0xAB, 0xEF, 0xCD, 0xAB, 0x00, 0x00]), result);
+  });
+
+
+  /**
+   * Going from numbers to hash strings should be lossless for up to 53 bits of
+   * precision.
+   */
+  it('testNumberToHashConversion', function() {
+    var result;
+    var convert = jspb.utils.numberToHash64;
+
+    result = convert(0x0000000000000);
+    assertEquals('0x0000000000000000', jspb.utils.hash64ToHexString(result));
+
+    result = convert(0xFFFFFFFFFFFFF);
+    assertEquals('0x000fffffffffffff', jspb.utils.hash64ToHexString(result));
+
+    result = convert(0x123456789ABCD);
+    assertEquals('0x000123456789abcd', jspb.utils.hash64ToHexString(result));
+
+    result = convert(0xDCBA987654321);
+    assertEquals('0x000dcba987654321', jspb.utils.hash64ToHexString(result));
+
+    // 53 bits of precision should not be truncated.
+    result = convert(0x10000000000001);
+    assertEquals('0x0010000000000001', jspb.utils.hash64ToHexString(result));
+
+    // 54 bits of precision should be truncated.
+    result = convert(0x20000000000001);
+    assertNotEquals(
+        '0x0020000000000001', jspb.utils.hash64ToHexString(result));
+  });
+
+
+  /**
+   * Sanity check the behavior of Javascript's strings when doing funny things
+   * with unicode characters.
+   */
+  it('sanityCheckUnicodeStrings', function() {
+    var strings = new Array(65536);
+
+    // All possible unsigned 16-bit values should be storable in a string, they
+    // shouldn't do weird things with the length of the string, and they should
+    // come back out of the string unchanged.
+    for (var i = 0; i < 65536; i++) {
+      strings[i] = 'a' + String.fromCharCode(i) + 'a';
+      if (3 != strings[i].length) throw 'fail!';
+      if (i != strings[i].charCodeAt(1)) throw 'fail!';
+    }
+
+    // Each unicode character should compare equal to itself and not equal to a
+    // different unicode character.
+    for (var i = 0; i < 65536; i++) {
+      if (strings[i] != strings[i]) throw 'fail!';
+      if (strings[i] == strings[(i + 1) % 65536]) throw 'fail!';
+    }
+  });
+
+
+  /**
+   * Tests conversion from 32-bit floating point numbers to split64 numbers.
+   */
+  it('testFloat32ToSplit64', function() {
+    var f32_eps = jspb.BinaryConstants.FLOAT32_EPS;
+    var f32_min = jspb.BinaryConstants.FLOAT32_MIN;
+    var f32_max = jspb.BinaryConstants.FLOAT32_MAX;
+
+    // NaN.
+    jspb.utils.splitFloat32(NaN);
+    if (!isNaN(jspb.utils.joinFloat32(jspb.utils.split64Low,
+                                         jspb.utils.split64High))) {
+      throw 'fail!';
+    }
+
+    /**
+     * @param {number} x
+     * @param {number=} opt_bits
+     */
+    function test(x, opt_bits) {
+      jspb.utils.splitFloat32(x);
+      if (goog.isDef(opt_bits)) {
+        if (opt_bits != jspb.utils.split64Low) throw 'fail!';
+      }
+      if (truncate(x) != jspb.utils.joinFloat32(jspb.utils.split64Low,
+                                                   jspb.utils.split64High)) {
+        throw 'fail!';
+      }
+    }
+
+    // Positive and negative infinity.
+    test(Infinity, 0x7f800000);
+    test(-Infinity, 0xff800000);
+
+    // Positive and negative zero.
+    test(0, 0x00000000);
+    test(-0, 0x80000000);
+
+    // Positive and negative epsilon.
+    test(f32_eps, 0x00000001);
+    test(-f32_eps, 0x80000001);
+
+    // Positive and negative min.
+    test(f32_min, 0x00800000);
+    test(-f32_min, 0x80800000);
+
+    // Positive and negative max.
+    test(f32_max, 0x7F7FFFFF);
+    test(-f32_max, 0xFF7FFFFF);
+
+    // Various positive values.
+    var cursor = f32_eps * 10;
+    while (cursor != Infinity) {
+      test(cursor);
+      cursor *= 1.1;
+    }
+
+    // Various negative values.
+    cursor = -f32_eps * 10;
+    while (cursor != -Infinity) {
+      test(cursor);
+      cursor *= 1.1;
+    }
+  });
+
+
+  /**
+   * Tests conversion from 64-bit floating point numbers to split64 numbers.
+   */
+  it('testFloat64ToSplit64', function() {
+    var f64_eps = jspb.BinaryConstants.FLOAT64_EPS;
+    var f64_min = jspb.BinaryConstants.FLOAT64_MIN;
+    var f64_max = jspb.BinaryConstants.FLOAT64_MAX;
+
+    // NaN.
+    jspb.utils.splitFloat64(NaN);
+    if (!isNaN(jspb.utils.joinFloat64(jspb.utils.split64Low,
+                                         jspb.utils.split64High))) {
+      throw 'fail!';
+    }
+
+    /**
+     * @param {number} x
+     * @param {number=} opt_highBits
+     * @param {number=} opt_lowBits
+     */
+    function test(x, opt_highBits, opt_lowBits) {
+      jspb.utils.splitFloat64(x);
+      if (goog.isDef(opt_highBits)) {
+        if (opt_highBits != jspb.utils.split64High) throw 'fail!';
+      }
+      if (goog.isDef(opt_lowBits)) {
+        if (opt_lowBits != jspb.utils.split64Low) throw 'fail!';
+      }
+      if (x != jspb.utils.joinFloat64(jspb.utils.split64Low,
+                                         jspb.utils.split64High)) {
+        throw 'fail!';
+      }
+    }
+
+    // Positive and negative infinity.
+    test(Infinity, 0x7ff00000, 0x00000000);
+    test(-Infinity, 0xfff00000, 0x00000000);
+
+    // Positive and negative zero.
+    test(0, 0x00000000, 0x00000000);
+    test(-0, 0x80000000, 0x00000000);
+
+    // Positive and negative epsilon.
+    test(f64_eps, 0x00000000, 0x00000001);
+    test(-f64_eps, 0x80000000, 0x00000001);
+
+    // Positive and negative min.
+    test(f64_min, 0x00100000, 0x00000000);
+    test(-f64_min, 0x80100000, 0x00000000);
+
+    // Positive and negative max.
+    test(f64_max, 0x7FEFFFFF, 0xFFFFFFFF);
+    test(-f64_max, 0xFFEFFFFF, 0xFFFFFFFF);
+
+    // Various positive values.
+    var cursor = f64_eps * 10;
+    while (cursor != Infinity) {
+      test(cursor);
+      cursor *= 1.1;
+    }
+
+    // Various negative values.
+    cursor = -f64_eps * 10;
+    while (cursor != -Infinity) {
+      test(cursor);
+      cursor *= 1.1;
+    }
+  });
+
+
+  /**
+   * Tests counting packed varints.
+   */
+  it('testCountVarints', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.rawWriteVarint(Math.floor(i));
+      count++;
+    }
+
+    var buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count, jspb.utils.countVarints(buffer, 0, buffer.length));
+  });
+
+
+  /**
+   * Tests counting matching varint fields.
+   */
+  it('testCountVarintFields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeUint64(1, Math.floor(i));
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    var buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countVarintFields(buffer, 0, buffer.length, 1));
+
+    writer = new jspb.BinaryWriter();
+
+    count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeUint64(123456789, Math.floor(i));
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countVarintFields(buffer, 0, buffer.length, 123456789));
+  });
+
+
+  /**
+   * Tests counting matching fixed32 fields.
+   */
+  it('testCountFixed32Fields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeFixed32(1, Math.floor(i));
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    var buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countFixed32Fields(buffer, 0, buffer.length, 1));
+
+    writer = new jspb.BinaryWriter();
+
+    count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeFixed32(123456789, Math.floor(i));
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countFixed32Fields(buffer, 0, buffer.length, 123456789));
+  });
+
+
+  /**
+   * Tests counting matching fixed64 fields.
+   */
+  it('testCountFixed64Fields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeDouble(1, i);
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    var buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countFixed64Fields(buffer, 0, buffer.length, 1));
+
+    writer = new jspb.BinaryWriter();
+
+    count = 0;
+    for (var i = 1; i < 1000000000; i *= 1.1) {
+      writer.writeDouble(123456789, i);
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countFixed64Fields(buffer, 0, buffer.length, 123456789));
+  });
+
+
+  /**
+   * Tests counting matching delimited fields.
+   */
+  it('testCountDelimitedFields', function() {
+    var writer = new jspb.BinaryWriter();
+
+    var count = 0;
+    for (var i = 1; i < 1000; i *= 1.1) {
+      writer.writeBytes(1, [Math.floor(i)]);
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    var buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countDelimitedFields(buffer, 0, buffer.length, 1));
+
+    writer = new jspb.BinaryWriter();
+
+    count = 0;
+    for (var i = 1; i < 1000; i *= 1.1) {
+      writer.writeBytes(123456789, [Math.floor(i)]);
+      count++;
+    }
+    writer.writeString(2, 'terminator');
+
+    buffer = new Uint8Array(writer.getResultBuffer());
+    assertEquals(count,
+        jspb.utils.countDelimitedFields(buffer, 0, buffer.length, 123456789));
+  });
+
+
+  /**
+   * Tests byte format for debug strings.
+   */
+  it('testDebugBytesToTextFormat', function() {
+    assertEquals('""', jspb.utils.debugBytesToTextFormat(null));
+    assertEquals('"\\x00\\x10\\xff"',
+        jspb.utils.debugBytesToTextFormat([0, 16, 255]));
+  });
+
+
+  /**
+   * Tests converting byte blob sources into byte blobs.
+   */
+  it('testByteSourceToUint8Array', function() {
+    var convert = jspb.utils.byteSourceToUint8Array;
+
+    var sourceData = [];
+    for (var i = 0; i < 256; i++) {
+      sourceData.push(i);
+    }
+
+    var sourceBytes = new Uint8Array(sourceData);
+    var sourceBuffer = sourceBytes.buffer;
+    var sourceBase64 = goog.crypt.base64.encodeByteArray(sourceData);
+    var sourceString = String.fromCharCode.apply(null, sourceData);
+
+    function check(result) {
+      assertEquals(Uint8Array, result.constructor);
+      assertEquals(sourceData.length, result.length);
+      for (var i = 0; i < result.length; i++) {
+        assertEquals(sourceData[i], result[i]);
+      }
+    }
+
+    // Converting Uint8Arrays into Uint8Arrays should be a no-op.
+    assertEquals(sourceBytes, convert(sourceBytes));
+
+    // Converting Array.<numbers> into Uint8Arrays should work.
+    check(convert(sourceData));
+
+    // Converting ArrayBuffers into Uint8Arrays should work.
+    check(convert(sourceBuffer));
+
+    // Converting base64-encoded strings into Uint8Arrays should work.
+    check(convert(sourceBase64));
+
+    // Converting binary-data strings into Uint8Arrays should work.
+    check(convert(sourceString, /* opt_stringIsRawBytes = */ true));
+  });
+});
diff --git a/js/binary/writer.js b/js/binary/writer.js
new file mode 100644
index 00000000..a1849457
--- /dev/null
+++ b/js/binary/writer.js
@@ -0,0 +1,2124 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview This file contains utilities for encoding Javascript objects
+ * into binary, wire-format protocol buffers (in the form of Uint8Arrays) that
+ * a server can consume directly.
+ *
+ * jspb's BinaryWriter class defines methods for efficiently encoding
+ * Javascript objects into binary, wire-format protocol buffers and supports
+ * all the fundamental field types used in protocol buffers.
+ *
+ * Major caveat 1 - Users of this library _must_ keep their Javascript proto
+ * parsing code in sync with the original .proto file - presumably you'll be
+ * using the typed jspb code generator, but if you bypass that you'll need
+ * to keep things in sync by hand.
+ *
+ * Major caveat 2 - Javascript is unable to accurately represent integers
+ * larger than 2^53 due to its use of a double-precision floating point format
+ * for all numbers. BinaryWriter does not make any special effort to preserve
+ * precision for values above this limit - if you need to pass 64-bit integers
+ * (hash codes, for example) between the client and server without precision
+ * loss, do _not_ use this library.
+ *
+ * Major caveat 3 - This class uses typed arrays and must not be used on older
+ * browsers that do not support them.
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.provide('jspb.BinaryWriter');
+
+goog.require('goog.asserts');
+goog.require('goog.crypt.base64');
+goog.require('jspb.BinaryConstants');
+goog.require('jspb.arith.Int64');
+goog.require('jspb.arith.UInt64');
+goog.require('jspb.utils');
+
+goog.forwardDeclare('jspb.Message');
+
+
+
+/**
+ * BinaryWriter implements encoders for all the wire types specified in
+ * https://developers.google.com/protocol-buffers/docs/encoding.
+ *
+ * @constructor
+ * @struct
+ */
+jspb.BinaryWriter = function() {
+  /**
+   * Blocks of serialized data that will be concatenated once all messages have
+   * been written.
+   * @private {!Array<!Uint8Array|!Array<number>>}
+   */
+  this.blocks_ = [];
+
+  /**
+   * Total number of bytes in the blocks_ array. Does _not_ include the temp
+   * buffer.
+   * @private {number}
+   */
+  this.totalLength_ = 0;
+
+  /**
+   * Temporary buffer holding a message that we're still serializing. When we
+   * get to a stopping point (either the start of a new submessage, or when we
+   * need to append a raw Uint8Array), the temp buffer will be added to the
+   * block array above and a new temp buffer will be created.
+   * @private {!Array.<number>}
+   */
+  this.temp_ = [];
+
+  /**
+   * A stack of bookmarks containing the parent blocks for each message started
+   * via beginSubMessage(), needed as bookkeeping for endSubMessage().
+   * TODO(aappleby): Deprecated, users should be calling writeMessage().
+   * @private {!Array.<!jspb.BinaryWriter.Bookmark_>}
+   */
+  this.bookmarks_ = [];
+};
+
+
+/**
+ * @typedef {{block: !Array.<number>, length: number}}
+ * @private
+ */
+jspb.BinaryWriter.Bookmark_;
+
+
+/**
+ * Saves the current temp buffer in the blocks_ array and starts a new one.
+ * @return {!Array.<number>} Returns a reference to the old temp buffer.
+ * @private
+ */
+jspb.BinaryWriter.prototype.saveTempBuffer_ = function() {
+  var oldTemp = this.temp_;
+  this.blocks_.push(this.temp_);
+  this.totalLength_ += this.temp_.length;
+  this.temp_ = [];
+  return oldTemp;
+};
+
+
+/**
+ * Append a typed array of bytes onto the buffer.
+ *
+ * @param {!Uint8Array} arr The byte array to append.
+ * @private
+ */
+jspb.BinaryWriter.prototype.appendUint8Array_ = function(arr) {
+  if (this.temp_.length) {
+    this.saveTempBuffer_();
+  }
+  this.blocks_.push(arr);
+  this.totalLength_ += arr.length;
+};
+
+
+/**
+ * Append an untyped array of bytes onto the buffer.
+ *
+ * @param {!Array.<number>} arr The byte array to append.
+ * @private
+ */
+jspb.BinaryWriter.prototype.appendArray_ = function(arr) {
+  if (this.temp_.length) {
+    this.saveTempBuffer_();
+  }
+  this.temp_ = arr;
+};
+
+
+/**
+ * Begins a length-delimited section by writing the field header to the current
+ * temp buffer and then saving it in the block array. Returns the saved block,
+ * which we will append the length to in endDelimited_ below.
+ * @param {number} field
+ * @return {!jspb.BinaryWriter.Bookmark_}
+ * @private
+ */
+jspb.BinaryWriter.prototype.beginDelimited_ = function(field) {
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+  return {block: this.saveTempBuffer_(), length: this.totalLength_};
+};
+
+
+/**
+ * Ends a length-delimited block by encoding the _change_ in length of the
+ * buffer to the parent block and adds the number of bytes needed to encode
+ * that length to the total byte length. Note that 'parentLength' _must_ be the
+ * total length _after_ the field header was written in beginDelimited_ above.
+ * @param {!jspb.BinaryWriter.Bookmark_} bookmark
+ * @private
+ */
+jspb.BinaryWriter.prototype.endDelimited_ = function(bookmark) {
+  var messageLength = this.totalLength_ + this.temp_.length - bookmark.length;
+  goog.asserts.assert(messageLength >= 0);
+
+  var bytes = 1;
+  while (messageLength > 127) {
+    bookmark.block.push((messageLength & 0x7f) | 0x80);
+    messageLength = messageLength >>> 7;
+    bytes++;
+  }
+
+  bookmark.block.push(messageLength);
+  this.totalLength_ += bytes;
+};
+
+
+/**
+ * Resets the writer, throwing away any accumulated buffers.
+ */
+jspb.BinaryWriter.prototype.reset = function() {
+  this.blocks_ = [];
+  this.temp_ = [];
+  this.totalLength_ = 0;
+  this.bookmarks_ = [];
+};
+
+
+/**
+ * Converts the encoded data into a Uint8Array.
+ * @return {!Uint8Array}
+ */
+jspb.BinaryWriter.prototype.getResultBuffer = function() {
+  goog.asserts.assert(this.bookmarks_.length == 0);
+
+  var flat = new Uint8Array(this.totalLength_ + this.temp_.length);
+
+  var blocks = this.blocks_;
+  var blockCount = blocks.length;
+  var offset = 0;
+
+  for (var i = 0; i < blockCount; i++) {
+    var block = blocks[i];
+    flat.set(block, offset);
+    offset += block.length;
+  }
+
+  flat.set(this.temp_, offset);
+  offset += this.temp_.length;
+
+  // Post condition: `flattened` must have had every byte written.
+  goog.asserts.assert(offset == flat.length);
+
+  // Replace our block list with the flattened block, which lets GC reclaim
+  // the temp blocks sooner.
+  this.blocks_ = [flat];
+  this.temp_ = [];
+
+  return flat;
+};
+
+
+/**
+ * Converts the encoded data into a bas64-encoded string.
+ * @return {string}
+ */
+jspb.BinaryWriter.prototype.getResultBase64String = function() {
+  return goog.crypt.base64.encodeByteArray(this.getResultBuffer());
+};
+
+
+/**
+ * Begins a new sub-message. The client must call endSubMessage() when they're
+ * done.
+ * TODO(aappleby): Deprecated. Move callers to writeMessage().
+ * @param {number} field The field number of the sub-message.
+ */
+jspb.BinaryWriter.prototype.beginSubMessage = function(field) {
+  this.bookmarks_.push(this.beginDelimited_(field));
+};
+
+
+/**
+ * Finishes a sub-message and packs it into the parent messages' buffer.
+ * TODO(aappleby): Deprecated. Move callers to writeMessage().
+ */
+jspb.BinaryWriter.prototype.endSubMessage = function() {
+  goog.asserts.assert(this.bookmarks_.length >= 0);
+  this.endDelimited_(this.bookmarks_.pop());
+};
+
+
+/**
+ * Encodes a 32-bit unsigned integer into its wire-format varint representation
+ * and stores it in the buffer.
+ * @param {number} value The integer to convert.
+ */
+jspb.BinaryWriter.prototype.rawWriteUnsignedVarint32 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+
+  while (value > 127) {
+    this.temp_.push((value & 0x7f) | 0x80);
+    value = value >>> 7;
+  }
+
+  this.temp_.push(value);
+};
+
+
+/**
+ * Encodes a 32-bit signed integer into its wire-format varint representation
+ * and stores it in the buffer.
+ * @param {number} value The integer to convert.
+ */
+jspb.BinaryWriter.prototype.rawWriteSignedVarint32 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  if (value >= 0) {
+    this.rawWriteUnsignedVarint32(value);
+    return;
+  }
+
+  // Write nine bytes with a _signed_ right shift so we preserve the sign bit.
+  for (var i = 0; i < 9; i++) {
+    this.temp_.push((value & 0x7f) | 0x80);
+    value = value >> 7;
+  }
+
+  // The above loop writes out 63 bits, so the last byte is always the sign bit
+  // which is always set for negative numbers.
+  this.temp_.push(1);
+};
+
+
+/**
+ * Encodes an unsigned 64-bit integer in 32:32 split representation into its
+ * wire-format varint representation and stores it in the buffer.
+ * @param {number} lowBits The low 32 bits of the int.
+ * @param {number} highBits The high 32 bits of the int.
+ */
+jspb.BinaryWriter.prototype.rawWriteSplitVarint =
+    function(lowBits, highBits) {
+  // Break the binary representation into chunks of 7 bits, set the 8th bit
+  // in each chunk if it's not the final chunk, and append to the result.
+  while (highBits > 0 || lowBits > 127) {
+    this.temp_.push((lowBits & 0x7f) | 0x80);
+    lowBits = ((lowBits >>> 7) | (highBits << 25)) >>> 0;
+    highBits = highBits >>> 7;
+  }
+  this.temp_.push(lowBits);
+};
+
+
+/**
+ * Encodes a JavaScript integer into its wire-format varint representation and
+ * stores it in the buffer. Due to the way the varint encoding works this
+ * behaves correctly for both signed and unsigned integers, though integers
+ * that are not representable in 64 bits will still be truncated.
+ * @param {number} value The integer to convert.
+ */
+jspb.BinaryWriter.prototype.rawWriteVarint = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  jspb.utils.splitInt64(value);
+  this.rawWriteSplitVarint(jspb.utils.split64Low,
+                           jspb.utils.split64High);
+};
+
+
+/**
+ * Encodes a jspb.arith.{Int64,UInt64} instance into its wire-format
+ * varint representation and stores it in the buffer. Due to the way the varint
+ * encoding works this behaves correctly for both signed and unsigned integers,
+ * though integers that are not representable in 64 bits will still be
+ * truncated.
+ * @param {jspb.arith.Int64|jspb.arith.UInt64} value
+ */
+jspb.BinaryWriter.prototype.rawWriteVarintFromNum = function(value) {
+  this.rawWriteSplitVarint(value.lo, value.hi);
+};
+
+
+/**
+ * Encodes a JavaScript integer into its wire-format, zigzag-encoded varint
+ * representation and stores it in the buffer.
+ * @param {number} value The integer to convert.
+ */
+jspb.BinaryWriter.prototype.rawWriteZigzagVarint32 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  this.rawWriteUnsignedVarint32(((value << 1) ^ (value >> 31)) >>> 0);
+};
+
+
+/**
+ * Encodes a JavaScript integer into its wire-format, zigzag-encoded varint
+ * representation and stores it in the buffer. Integers not representable in 64
+ * bits will be truncated.
+ * @param {number} value The integer to convert.
+ */
+jspb.BinaryWriter.prototype.rawWriteZigzagVarint = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  jspb.utils.splitZigzag64(value);
+  this.rawWriteSplitVarint(jspb.utils.split64Low,
+                           jspb.utils.split64High);
+};
+
+
+/**
+ * Writes a raw 8-bit unsigned integer to the buffer. Numbers outside the range
+ * [0,2^8) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteUint8 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= 0) && (value < 256));
+  this.temp_.push((value >>> 0) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 16-bit unsigned integer to the buffer. Numbers outside the
+ * range [0,2^16) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteUint16 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= 0) && (value < 65536));
+  this.temp_.push((value >>> 0) & 0xFF);
+  this.temp_.push((value >>> 8) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 32-bit unsigned integer to the buffer. Numbers outside the
+ * range [0,2^32) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteUint32 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_32));
+  this.temp_.push((value >>> 0) & 0xFF);
+  this.temp_.push((value >>> 8) & 0xFF);
+  this.temp_.push((value >>> 16) & 0xFF);
+  this.temp_.push((value >>> 24) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 64-bit unsigned integer to the buffer. Numbers outside the
+ * range [0,2^64) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteUint64 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_64));
+  jspb.utils.splitUint64(value);
+  this.rawWriteUint32(jspb.utils.split64Low);
+  this.rawWriteUint32(jspb.utils.split64High);
+};
+
+
+/**
+ * Writes a raw 8-bit integer to the buffer. Numbers outside the range
+ * [-2^7,2^7) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteInt8 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= -128) && (value < 128));
+  this.temp_.push((value >>> 0) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 16-bit integer to the buffer. Numbers outside the range
+ * [-2^15,2^15) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteInt16 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= -32768) && (value < 32768));
+  this.temp_.push((value >>> 0) & 0xFF);
+  this.temp_.push((value >>> 8) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 32-bit integer to the buffer. Numbers outside the range
+ * [-2^31,2^31) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteInt32 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.temp_.push((value >>> 0) & 0xFF);
+  this.temp_.push((value >>> 8) & 0xFF);
+  this.temp_.push((value >>> 16) & 0xFF);
+  this.temp_.push((value >>> 24) & 0xFF);
+};
+
+
+/**
+ * Writes a raw 64-bit integer to the buffer. Numbers outside the range
+ * [-2^63,2^63) will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteInt64 = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_63) &&
+                      (value < jspb.BinaryConstants.TWO_TO_63));
+  jspb.utils.splitInt64(value);
+  this.rawWriteUint32(jspb.utils.split64Low);
+  this.rawWriteUint32(jspb.utils.split64High);
+};
+
+
+/**
+ * Writes a raw single-precision floating point value to the buffer. Numbers
+ * requiring more than 32 bits of precision will be truncated.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteFloat = function(value) {
+  jspb.utils.splitFloat32(value);
+  this.rawWriteUint32(jspb.utils.split64Low);
+};
+
+
+/**
+ * Writes a raw double-precision floating point value to the buffer. As this is
+ * the native format used by JavaScript, no precision will be lost.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteDouble = function(value) {
+  jspb.utils.splitFloat64(value);
+  this.rawWriteUint32(jspb.utils.split64Low);
+  this.rawWriteUint32(jspb.utils.split64High);
+};
+
+
+/**
+ * Writes a raw boolean value to the buffer as a varint.
+ * @param {boolean} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteBool = function(value) {
+  goog.asserts.assert(goog.isBoolean(value));
+  this.temp_.push(~~value);
+};
+
+
+/**
+ * Writes an raw enum value to the buffer as a varint.
+ * @param {number} value The value to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteEnum = function(value) {
+  goog.asserts.assert(value == Math.floor(value));
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.rawWriteSignedVarint32(value);
+};
+
+
+/**
+ * Writes a raw string value to the buffer.
+ * @param {string} string The string to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteUtf8String = function(string) {
+  for (var i = 0; i < string.length; i++) {
+    this.temp_.push(string.charCodeAt(i));
+  }
+};
+
+
+/**
+ * Writes an arbitrary raw byte array to the buffer.
+ * @param {!Uint8Array} bytes The array of bytes to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteBytes = function(bytes) {
+  this.appendUint8Array_(bytes);
+};
+
+
+/**
+ * Writes an arbitrary raw byte array to the buffer.
+ * @param {!Uint8Array} bytes The array of bytes to write.
+ * @param {number} start The start of the range to write.
+ * @param {number} end The end of the range to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteByteRange = function(bytes, start, end) {
+  this.appendUint8Array_(bytes.subarray(start, end));
+};
+
+
+/**
+ * Writes a 64-bit hash string (8 characters @ 8 bits of data each) to the
+ * buffer as a varint.
+ * @param {string} hash The hash to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteVarintHash64 = function(hash) {
+  jspb.utils.splitHash64(hash);
+  this.rawWriteSplitVarint(jspb.utils.split64Low,
+                           jspb.utils.split64High);
+};
+
+
+/**
+ * Writes a 64-bit hash string (8 characters @ 8 bits of data each) to the
+ * buffer as a fixed64.
+ * @param {string} hash The hash to write.
+ */
+jspb.BinaryWriter.prototype.rawWriteFixedHash64 = function(hash) {
+  jspb.utils.splitHash64(hash);
+  this.rawWriteUint32(jspb.utils.split64Low);
+  this.rawWriteUint32(jspb.utils.split64High);
+};
+
+
+/**
+ * Encodes a (field number, wire type) tuple into a wire-format field header
+ * and stores it in the buffer as a varint.
+ * @param {number} field The field number.
+ * @param {number} wireType The wire-type of the field, as specified in the
+ *     protocol buffer documentation.
+ * @private
+ */
+jspb.BinaryWriter.prototype.rawWriteFieldHeader_ =
+    function(field, wireType) {
+  goog.asserts.assert(field >= 1 && field == Math.floor(field));
+  var x = field * 8 + wireType;
+  this.rawWriteUnsignedVarint32(x);
+};
+
+
+/**
+ * Writes a field of any valid scalar type to the binary stream.
+ * @param {jspb.BinaryConstants.FieldType} fieldType
+ * @param {number} field
+ * @param {jspb.AnyFieldType} value
+ */
+jspb.BinaryWriter.prototype.writeAny = function(fieldType, field, value) {
+  var fieldTypes = jspb.BinaryConstants.FieldType;
+  switch (fieldType) {
+    case fieldTypes.DOUBLE:
+      this.writeDouble(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.FLOAT:
+      this.writeFloat(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.INT64:
+      this.writeInt64(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.UINT64:
+      this.writeUint64(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.INT32:
+      this.writeInt32(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.FIXED64:
+      this.writeFixed64(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.FIXED32:
+      this.writeFixed32(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.BOOL:
+      this.writeBool(field, /** @type {boolean} */(value));
+      return;
+    case fieldTypes.STRING:
+      this.writeString(field, /** @type {string} */(value));
+      return;
+    case fieldTypes.GROUP:
+      goog.asserts.fail('Group field type not supported in writeAny()');
+      return;
+    case fieldTypes.MESSAGE:
+      goog.asserts.fail('Message field type not supported in writeAny()');
+      return;
+    case fieldTypes.BYTES:
+      this.writeBytes(field, /** @type {?Uint8Array} */(value));
+      return;
+    case fieldTypes.UINT32:
+      this.writeUint32(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.ENUM:
+      this.writeEnum(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.SFIXED32:
+      this.writeSfixed32(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.SFIXED64:
+      this.writeSfixed64(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.SINT32:
+      this.writeSint32(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.SINT64:
+      this.writeSint64(field, /** @type {number} */(value));
+      return;
+    case fieldTypes.FHASH64:
+      this.writeFixedHash64(field, /** @type {string} */(value));
+      return;
+    case fieldTypes.VHASH64:
+      this.writeVarintHash64(field, /** @type {string} */(value));
+      return;
+    default:
+      goog.asserts.fail('Invalid field type in writeAny()');
+      return;
+  }
+};
+
+
+/**
+ * Writes a varint field to the buffer without range checking.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeUnsignedVarint32_ = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteSignedVarint32(value);
+};
+
+
+/**
+ * Writes a varint field to the buffer without range checking.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeSignedVarint32_ = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteSignedVarint32(value);
+};
+
+
+/**
+ * Writes a varint field to the buffer without range checking.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeVarint_ = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteVarint(value);
+};
+
+
+/**
+ * Writes a zigzag varint field to the buffer without range checking.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeZigzagVarint32_ = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteZigzagVarint32(value);
+};
+
+
+/**
+ * Writes a zigzag varint field to the buffer without range checking.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeZigzagVarint_ = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteZigzagVarint(value);
+};
+
+
+/**
+ * Writes an int32 field to the buffer. Numbers outside the range [-2^31,2^31)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeInt32 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.writeSignedVarint32_(field, value);
+};
+
+
+/**
+ * Writes an int32 field represented as a string to the buffer. Numbers outside
+ * the range [-2^31,2^31) will be truncated.
+ * @param {number} field The field number.
+ * @param {string?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeInt32String = function(field, value) {
+  if (value == null) return;
+  var intValue = /** {number} */ parseInt(value, 10);
+  goog.asserts.assert((intValue >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (intValue < jspb.BinaryConstants.TWO_TO_31));
+  this.writeSignedVarint32_(field, intValue);
+};
+
+
+/**
+ * Writes an int64 field to the buffer. Numbers outside the range [-2^63,2^63)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeInt64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_63) &&
+                      (value < jspb.BinaryConstants.TWO_TO_63));
+  this.writeVarint_(field, value);
+};
+
+
+/**
+ * Writes a int64 field (with value as a string) to the buffer.
+ * @param {number} field The field number.
+ * @param {string?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeInt64String = function(field, value) {
+  if (value == null) return;
+  var num = jspb.arith.Int64.fromString(value);
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteVarintFromNum(num);
+};
+
+
+/**
+ * Writes a uint32 field to the buffer. Numbers outside the range [0,2^32)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeUint32 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_32));
+  this.writeUnsignedVarint32_(field, value);
+};
+
+
+/**
+ * Writes a uint32 field represented as a string to the buffer. Numbers outside
+ * the range [0,2^32) will be truncated.
+ * @param {number} field The field number.
+ * @param {string?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeUint32String = function(field, value) {
+  if (value == null) return;
+  var intValue = /** {number} */ parseInt(value, 10);
+  goog.asserts.assert((intValue >= 0) &&
+                      (intValue < jspb.BinaryConstants.TWO_TO_32));
+  this.writeUnsignedVarint32_(field, intValue);
+};
+
+
+/**
+ * Writes a uint64 field to the buffer. Numbers outside the range [0,2^64)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeUint64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_64));
+  this.writeVarint_(field, value);
+};
+
+
+/**
+ * Writes a uint64 field (with value as a string) to the buffer.
+ * @param {number} field The field number.
+ * @param {string?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeUint64String = function(field, value) {
+  if (value == null) return;
+  var num = jspb.arith.UInt64.fromString(value);
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteVarintFromNum(num);
+};
+
+
+/**
+ * Writes a sint32 field to the buffer. Numbers outside the range [-2^31,2^31)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeSint32 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.writeZigzagVarint32_(field, value);
+};
+
+
+/**
+ * Writes a sint64 field to the buffer. Numbers outside the range [-2^63,2^63)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeSint64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_63) &&
+                      (value < jspb.BinaryConstants.TWO_TO_63));
+  this.writeZigzagVarint_(field, value);
+};
+
+
+/**
+ * Writes a fixed32 field to the buffer. Numbers outside the range [0,2^32)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeFixed32 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_32));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED32);
+  this.rawWriteUint32(value);
+};
+
+
+/**
+ * Writes a fixed64 field to the buffer. Numbers outside the range [0,2^64)
+ * will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeFixed64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= 0) &&
+                      (value < jspb.BinaryConstants.TWO_TO_64));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED64);
+  this.rawWriteUint64(value);
+};
+
+
+/**
+ * Writes a sfixed32 field to the buffer. Numbers outside the range
+ * [-2^31,2^31) will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeSfixed32 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED32);
+  this.rawWriteInt32(value);
+};
+
+
+/**
+ * Writes a sfixed64 field to the buffer. Numbers outside the range
+ * [-2^63,2^63) will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeSfixed64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_63) &&
+                      (value < jspb.BinaryConstants.TWO_TO_63));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED64);
+  this.rawWriteInt64(value);
+};
+
+
+/**
+ * Writes a single-precision floating point field to the buffer. Numbers
+ * requiring more than 32 bits of precision will be truncated.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeFloat = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED32);
+  this.rawWriteFloat(value);
+};
+
+
+/**
+ * Writes a double-precision floating point field to the buffer. As this is the
+ * native format used by JavaScript, no precision will be lost.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeDouble = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED64);
+  this.rawWriteDouble(value);
+};
+
+
+/**
+ * Writes a boolean field to the buffer.
+ * @param {number} field The field number.
+ * @param {boolean?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeBool = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert(goog.isBoolean(value));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.temp_.push(~~value);
+};
+
+
+/**
+ * Writes an enum field to the buffer.
+ * @param {number} field The field number.
+ * @param {number?} value The value to write.
+ */
+jspb.BinaryWriter.prototype.writeEnum = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert((value >= -jspb.BinaryConstants.TWO_TO_31) &&
+                      (value < jspb.BinaryConstants.TWO_TO_31));
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteSignedVarint32(value);
+};
+
+
+/**
+ * Writes a string field to the buffer.
+ * @param {number} field The field number.
+ * @param {string?} value The string to write.
+ */
+jspb.BinaryWriter.prototype.writeString = function(field, value) {
+  if (value == null) return;
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+
+  // Conversion loop swiped from goog.crypt.stringToUtf8ByteArray. Note that
+  // 'bytes' will be at least as long as 'value', but could be longer if we
+  // need to unpack unicode characters.
+  var bytes = [];
+  for (var i = 0; i < value.length; i++) {
+    var c = value.charCodeAt(i);
+    if (c < 128) {
+      bytes.push(c);
+    } else if (c < 2048) {
+      bytes.push((c >> 6) | 192);
+      bytes.push((c & 63) | 128);
+    } else {
+      bytes.push((c >> 12) | 224);
+      bytes.push(((c >> 6) & 63) | 128);
+      bytes.push((c & 63) | 128);
+    }
+  }
+
+  this.rawWriteUnsignedVarint32(bytes.length);
+  this.appendArray_(bytes);
+};
+
+
+/**
+ * Writes an arbitrary byte field to the buffer. Note - to match the behavior
+ * of the C++ implementation, empty byte arrays _are_ serialized.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {jspb.ByteSource} value The array of bytes to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @param {boolean=} opt_stringIsRawBytes If `value` is a string, interpret it
+ * as a series of raw bytes (codepoints 0--255 inclusive) rather than base64
+ * data.
+ */
+jspb.BinaryWriter.prototype.writeBytes =
+    function(field, value, opt_buffer, opt_start, opt_end,
+             opt_stringIsRawBytes) {
+  if (value != null) {
+    this.rawWriteFieldHeader_(field,
+        jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length);
+    this.rawWriteBytes(
+        jspb.utils.byteSourceToUint8Array(value, opt_stringIsRawBytes));
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an arbitrary byte field to the buffer, with `opt_stringIsRawBytes`
+ * flag implicitly true.
+ * @param {number} field
+ * @param {jspb.ByteSource} value The array of bytes to write.
+ */
+jspb.BinaryWriter.prototype.writeBytesRawString = function(field, value) {
+  this.writeBytes(field, value, null, null, null, true);
+};
+
+
+/**
+ * Writes a message to the buffer.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @template MessageType
+ * @param {number} field The field number.
+ * @param {?MessageType} value The message to write.
+ * @param {!jspb.WriterFunction} writerCallback Will be invoked with the value
+ *     to write and the writer to write it with.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writeMessage =
+    function(field, value, writerCallback, opt_buffer, opt_start, opt_end) {
+  if (value !== null) {
+    var bookmark = this.beginDelimited_(field);
+
+    writerCallback(value, this);
+
+    this.endDelimited_(bookmark);
+  } else if (opt_buffer && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes a group message to the buffer.
+ *
+ * @template MessageType
+ * @param {number} field The field number.
+ * @param {?MessageType} value The message to write, wrapped with START_GROUP /
+ *     END_GROUP tags. Will be a no-op if 'value' is null.
+ * @param {!jspb.WriterFunction} writerCallback Will be invoked with the value
+ *     to write and the writer to write it with.
+ */
+jspb.BinaryWriter.prototype.writeGroup =
+    function(field, value, writerCallback) {
+  if (value) {
+    this.rawWriteFieldHeader_(
+        field, jspb.BinaryConstants.WireType.START_GROUP);
+    writerCallback(value, this);
+    this.rawWriteFieldHeader_(
+        field, jspb.BinaryConstants.WireType.END_GROUP);
+  }
+};
+
+
+/**
+ * Writes a 64-bit hash string field (8 characters @ 8 bits of data each) to
+ * the buffer.
+ * @param {number} field The field number.
+ * @param {string?} value The hash string.
+ */
+jspb.BinaryWriter.prototype.writeFixedHash64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert(value.length == 8);
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.FIXED64);
+  this.rawWriteFixedHash64(value);
+};
+
+
+/**
+ * Writes a 64-bit hash string field (8 characters @ 8 bits of data each) to
+ * the buffer.
+ * @param {number} field The field number.
+ * @param {string?} value The hash string.
+ */
+jspb.BinaryWriter.prototype.writeVarintHash64 = function(field, value) {
+  if (value == null) return;
+  goog.asserts.assert(value.length == 8);
+  this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.VARINT);
+  this.rawWriteVarintHash64(value);
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated varint field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeRepeatedUnsignedVarint32_ =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeUnsignedVarint32_(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated varint field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeRepeatedSignedVarint32_ =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeSignedVarint32_(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated varint field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeRepeatedVarint_ = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeVarint_(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated zigzag field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeRepeatedZigzag32_ = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeZigzagVarint32_(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated zigzag field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writeRepeatedZigzag_ = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeZigzagVarint_(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated 32-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedInt32 =
+    jspb.BinaryWriter.prototype.writeRepeatedSignedVarint32_;
+
+
+/**
+ * Writes an array of numbers formatted as strings to the buffer as a repeated
+ * 32-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedInt32String =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeInt32String(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated 64-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedInt64 =
+    jspb.BinaryWriter.prototype.writeRepeatedVarint_;
+
+
+/**
+ * Writes an array of numbers formatted as strings to the buffer as a repeated
+ * 64-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedInt64String =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeInt64String(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a repeated unsigned 32-bit int
+ *     field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedUint32 =
+    jspb.BinaryWriter.prototype.writeRepeatedUnsignedVarint32_;
+
+
+/**
+ * Writes an array of numbers formatted as strings to the buffer as a repeated
+ * unsigned 32-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedUint32String =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeUint32String(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a repeated unsigned 64-bit int
+ *     field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedUint64 =
+    jspb.BinaryWriter.prototype.writeRepeatedVarint_;
+
+
+/**
+ * Writes an array of numbers formatted as strings to the buffer as a repeated
+ * unsigned 64-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedUint64String =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeUint64String(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a repeated signed 32-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedSint32 =
+    jspb.BinaryWriter.prototype.writeRepeatedZigzag32_;
+
+
+/**
+ * Writes an array numbers to the buffer as a repeated signed 64-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedSint64 =
+    jspb.BinaryWriter.prototype.writeRepeatedZigzag_;
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated fixed32 field. This
+ * works for both signed and unsigned fixed32s.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedFixed32 = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeFixed32(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated fixed64 field. This
+ * works for both signed and unsigned fixed64s.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedFixed64 = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeFixed64(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated sfixed32 field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedSfixed32 = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeSfixed32(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated sfixed64 field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedSfixed64 = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeSfixed64(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated float field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedFloat = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeFloat(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a repeated double field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedDouble = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeDouble(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of booleans to the buffer as a repeated bool field.
+ * @param {number} field The field number.
+ * @param {?Array.<boolean>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedBool = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeBool(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of enums to the buffer as a repeated enum field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedEnum = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeEnum(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of strings to the buffer as a repeated string field.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of strings to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedString = function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeString(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of arbitrary byte fields to the buffer.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<!Uint8Array|string>} value
+ *     The arrays of arrays of bytes to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @param {boolean=} opt_stringIsRawBytes Any values that are strings are
+ * interpreted as raw bytes rather than base64 data.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedBytes =
+    function(field, value, opt_buffer, opt_start, opt_end,
+             opt_stringIsRawBytes) {
+  if (value != null) {
+    for (var i = 0; i < value.length; i++) {
+      this.writeBytes(field, value[i], null, null, null, opt_stringIsRawBytes);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of arbitrary byte fields to the buffer, with
+ * `opt_stringIsRawBytes` implicitly true.
+ * @param {number} field
+ * @param {?Array.<string>} value
+ */
+jspb.BinaryWriter.prototype.writeRepeatedBytesRawString =
+    function(field, value) {
+  this.writeRepeatedBytes(field, value, null, null, null, true);
+};
+
+
+/**
+ * Writes an array of messages to the buffer.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @template MessageType
+ * @param {number} field The field number.
+ * @param {?Array.<!MessageType>} value The array of messages to
+ *    write.
+ * @param {!jspb.WriterFunction} writerCallback Will be invoked with the value
+ *     to write and the writer to write it with.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedMessage =
+    function(field, value, writerCallback, opt_buffer, opt_start, opt_end) {
+  if (value) {
+    for (var i = 0; i < value.length; i++) {
+      var bookmark = this.beginDelimited_(field);
+
+      writerCallback(value[i], this);
+
+      this.endDelimited_(bookmark);
+    }
+  } else if (opt_buffer && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of group messages to the buffer.
+ *
+ * @template MessageType
+ * @param {number} field The field number.
+ * @param {?Array.<!MessageType>} value The array of messages to
+ *    write.
+ * @param {!jspb.WriterFunction} writerCallback Will be invoked with the value
+ *     to write and the writer to write it with.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedGroup =
+    function(field, value, writerCallback) {
+  if (value) {
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteFieldHeader_(
+          field, jspb.BinaryConstants.WireType.START_GROUP);
+      writerCallback(value[i], this);
+      this.rawWriteFieldHeader_(
+          field, jspb.BinaryConstants.WireType.END_GROUP);
+    }
+  }
+};
+
+
+/**
+ * Writes a 64-bit hash string field (8 characters @ 8 bits of data each) to
+ * the buffer.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of hashes to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedFixedHash64 =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeFixedHash64(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes a repeated 64-bit hash string field (8 characters @ 8 bits of data
+ * each) to the buffer.
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of hashes to write.
+ */
+jspb.BinaryWriter.prototype.writeRepeatedVarintHash64 =
+    function(field, value) {
+  if (value == null) return;
+  for (var i = 0; i < value.length; i++) {
+    this.writeVarintHash64(field, value[i]);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed varint field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writePackedUnsignedVarint32_ =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteUnsignedVarint32(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed varint field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writePackedSignedVarint32_ =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteSignedVarint32(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed varint field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writePackedVarint_ =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteVarint(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed zigzag field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ * @private
+ */
+jspb.BinaryWriter.prototype.writePackedZigzag_ =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteZigzagVarint(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed 32-bit int field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedInt32 =
+    jspb.BinaryWriter.prototype.writePackedSignedVarint32_;
+
+
+/**
+ * Writes an array of numbers represented as strings to the buffer as a packed
+ * 32-bit int field.
+ * @param {number} field
+ * @param {?Array.<string>} value
+ */
+jspb.BinaryWriter.prototype.writePackedInt32String = function(field, value) {
+  if (value == null || !value.length) return;
+  var bookmark = this.beginDelimited_(field);
+  for (var i = 0; i < value.length; i++) {
+    this.rawWriteSignedVarint32(parseInt(value[i], 10));
+  }
+  this.endDelimited_(bookmark);
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed 64-bit int field.
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedInt64 =
+    jspb.BinaryWriter.prototype.writePackedVarint_;
+
+
+/**
+ * Writes an array of numbers represented as strings to the buffer as a packed
+ * 64-bit int field.
+ * @param {number} field
+ * @param {?Array.<string>} value
+ */
+jspb.BinaryWriter.prototype.writePackedInt64String =
+    function(field, value) {
+  if (value == null || !value.length) return;
+  var bookmark = this.beginDelimited_(field);
+  for (var i = 0; i < value.length; i++) {
+    var num = jspb.arith.Int64.fromString(value[i]);
+    this.rawWriteVarintFromNum(num);
+  }
+  this.endDelimited_(bookmark);
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a packed unsigned 32-bit int field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedUint32 =
+    jspb.BinaryWriter.prototype.writePackedUnsignedVarint32_;
+
+
+/**
+ * Writes an array of numbers represented as strings to the buffer as a packed
+ * unsigned 32-bit int field.
+ * @param {number} field
+ * @param {?Array.<string>} value
+ */
+jspb.BinaryWriter.prototype.writePackedUint32String =
+    function(field, value) {
+  if (value == null || !value.length) return;
+  var bookmark = this.beginDelimited_(field);
+  for (var i = 0; i < value.length; i++) {
+    this.rawWriteUnsignedVarint32(parseInt(value[i], 10));
+  }
+  this.endDelimited_(bookmark);
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a packed unsigned 64-bit int field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedUint64 =
+    jspb.BinaryWriter.prototype.writePackedVarint_;
+
+
+/**
+ * Writes an array of numbers represented as strings to the buffer as a packed
+ * unsigned 64-bit int field.
+ * @param {number} field
+ * @param {?Array.<string>} value
+ */
+jspb.BinaryWriter.prototype.writePackedUint64String =
+    function(field, value) {
+  if (value == null || !value.length) return;
+  var bookmark = this.beginDelimited_(field);
+  for (var i = 0; i < value.length; i++) {
+    var num = jspb.arith.UInt64.fromString(value[i]);
+    this.rawWriteVarintFromNum(num);
+  }
+  this.endDelimited_(bookmark);
+};
+
+
+/**
+ * Writes an array numbers to the buffer as a packed signed 32-bit int field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedSint32 =
+    jspb.BinaryWriter.prototype.writePackedZigzag_;
+
+
+/**
+ * Writes an array numbers to the buffer as a packed signed 64-bit int field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedSint64 =
+    jspb.BinaryWriter.prototype.writePackedZigzag_;
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed fixed32 field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedFixed32 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 4);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteUint32(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed fixed64 field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedFixed64 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 8);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteUint64(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed sfixed32 field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedSfixed32 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 4);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteInt32(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed sfixed64 field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedSfixed64 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 8);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteInt64(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed float field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedFloat =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 4);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteFloat(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of numbers to the buffer as a packed double field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedDouble =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 8);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteDouble(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of booleans to the buffer as a packed bool field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<boolean>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedBool =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteBool(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes an array of enums to the buffer as a packed enum field.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<number>} value The array of ints to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedEnum =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteEnum(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes a 64-bit hash string field (8 characters @ 8 bits of data each) to
+ * the buffer.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of hashes to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedFixedHash64 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    this.rawWriteFieldHeader_(field, jspb.BinaryConstants.WireType.DELIMITED);
+    this.rawWriteUnsignedVarint32(value.length * 8);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteFixedHash64(value[i]);
+    }
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
+
+
+/**
+ * Writes a 64-bit hash string field (8 characters @ 8 bits of data each) to
+ * the buffer.
+ *
+ * If 'value' is null, this method will try and copy the pre-serialized value
+ * in 'opt_buffer' if present.
+ *
+ * @param {number} field The field number.
+ * @param {?Array.<string>} value The array of hashes to write.
+ * @param {?Uint8Array=} opt_buffer A buffer containing pre-packed values.
+ * @param {?number=} opt_start The starting point in the above buffer.
+ * @param {?number=} opt_end The ending point in the above buffer.
+ */
+jspb.BinaryWriter.prototype.writePackedVarintHash64 =
+    function(field, value, opt_buffer, opt_start, opt_end) {
+  if (value != null && value.length) {
+    var bookmark = this.beginDelimited_(field);
+    for (var i = 0; i < value.length; i++) {
+      this.rawWriteVarintHash64(value[i]);
+    }
+    this.endDelimited_(bookmark);
+  } else if ((opt_buffer != null) && (opt_start != null) && (opt_end != null)) {
+    this.rawWriteByteRange(opt_buffer, opt_start, opt_end);
+  }
+};
diff --git a/js/binary/writer_test.js b/js/binary/writer_test.js
new file mode 100644
index 00000000..54d37a21
--- /dev/null
+++ b/js/binary/writer_test.js
@@ -0,0 +1,123 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Test cases for jspb's binary protocol buffer writer. In
+ * practice BinaryWriter is used to drive the Decoder and Reader test cases,
+ * so only writer-specific tests are here.
+ *
+ * Test suite is written using Jasmine -- see http://jasmine.github.io/
+ *
+ * @author aappleby@google.com (Austin Appleby)
+ */
+
+goog.require('goog.crypt');
+goog.require('goog.testing.asserts');
+goog.require('jspb.BinaryWriter');
+
+
+/**
+ * @param {function()} func This function should throw an error when run.
+ */
+function assertFails(func) {
+  var e = assertThrows(func);
+  console.log(e);
+  //assertNotNull(e.toString().match(/Error/));
+}
+
+
+describe('binaryWriterTest', function() {
+  /**
+   * Verifies that misuse of the writer class triggers assertions.
+   */
+  it('testWriteErrors', function() {
+    // Submessages with invalid field indices should assert.
+    var writer = new jspb.BinaryWriter();
+    var dummyMessage = /** @type {!jspb.BinaryMessage} */({});
+
+    assertFails(function() {
+      writer.writeMessage(-1, dummyMessage, goog.nullFunction);
+    });
+
+    // Writing invalid field indices should assert.
+    writer = new jspb.BinaryWriter();
+    assertFails(function() {writer.writeUint64(-1, 1);});
+
+    // Writing out-of-range field values should assert.
+    writer = new jspb.BinaryWriter();
+
+    assertFails(function() {writer.writeInt32(1, -Infinity);});
+    assertFails(function() {writer.writeInt32(1, Infinity);});
+
+    assertFails(function() {writer.writeInt64(1, -Infinity);});
+    assertFails(function() {writer.writeInt64(1, Infinity);});
+
+    assertFails(function() {writer.writeUint32(1, -1);});
+    assertFails(function() {writer.writeUint32(1, Infinity);});
+
+    assertFails(function() {writer.writeUint64(1, -1);});
+    assertFails(function() {writer.writeUint64(1, Infinity);});
+
+    assertFails(function() {writer.writeSint32(1, -Infinity);});
+    assertFails(function() {writer.writeSint32(1, Infinity);});
+
+    assertFails(function() {writer.writeSint64(1, -Infinity);});
+    assertFails(function() {writer.writeSint64(1, Infinity);});
+
+    assertFails(function() {writer.writeFixed32(1, -1);});
+    assertFails(function() {writer.writeFixed32(1, Infinity);});
+
+    assertFails(function() {writer.writeFixed64(1, -1);});
+    assertFails(function() {writer.writeFixed64(1, Infinity);});
+
+    assertFails(function() {writer.writeSfixed32(1, -Infinity);});
+    assertFails(function() {writer.writeSfixed32(1, Infinity);});
+
+    assertFails(function() {writer.writeSfixed64(1, -Infinity);});
+    assertFails(function() {writer.writeSfixed64(1, Infinity);});
+  });
+
+
+  /**
+   * Basic test of retrieving the result as a Uint8Array buffer
+   */
+  it('testGetResultBuffer', function() {
+    var expected = '0864120b48656c6c6f20776f726c641a0301020320c801';
+
+    var writer = new jspb.BinaryWriter();
+    writer.writeUint32(1, 100);
+    writer.writeString(2, 'Hello world');
+    writer.writeBytes(3, new Uint8Array([1, 2, 3]));
+    writer.writeUint32(4, 200);
+
+    var buffer = writer.getResultBuffer();
+    assertEquals(expected, goog.crypt.byteArrayToHex(buffer));
+  });
+});
diff --git a/js/data.proto b/js/data.proto
new file mode 100644
index 00000000..74a8a994
--- /dev/null
+++ b/js/data.proto
@@ -0,0 +1,51 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: mwr@google.com (Mark Rawling)
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+package jspb.test;
+
+// legacy data, must be nested
+message data {
+  message NestedData {
+    required string str = 1;
+  }
+}
+
+// new data, does not require nesting
+message UnnestedData {
+  required string str = 1;
+}
+
diff --git a/js/debug.js b/js/debug.js
new file mode 100644
index 00000000..48389118
--- /dev/null
+++ b/js/debug.js
@@ -0,0 +1,140 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Utilities to debug JSPB based proto objects.
+ */
+
+goog.provide('jspb.debug');
+
+goog.require('goog.array');
+goog.require('goog.asserts');
+goog.require('goog.object');
+goog.require('jspb.Message');
+
+
+/**
+ * Turns a proto into a human readable object that can i.e. be written to the
+ * console: {@code console.log(jspb.debug.dump(myProto))}.
+ * This function makes a best effort and may not work in all cases. It will not
+ * work in obfuscated and or optimized code.
+ * Use this in environments where {@see jspb.Message.prototype.toObject} is
+ * not available for code size reasons.
+ * @param {jspb.Message} message A jspb.Message.
+ * @return {Object}
+ */
+jspb.debug.dump = function(message) {
+  if (!goog.DEBUG) {
+    return null;
+  }
+  goog.asserts.assert(message instanceof jspb.Message,
+      'jspb.Message instance expected');
+  /** @type {Object} */
+  var object = message;
+  goog.asserts.assert(object['getExtension'],
+      'Only unobfuscated and unoptimized compilation modes supported.');
+  return /** @type {Object} */ (jspb.debug.dump_(message));
+};
+
+
+/**
+ * Recursively introspects a message and the values its getters return to
+ * make a best effort in creating a human readable representation of the
+ * message.
+ * @param {*} thing A jspb.Message, Array or primitive type to dump.
+ * @return {*}
+ * @private
+ */
+jspb.debug.dump_ = function(thing) {
+  var type = goog.typeOf(thing);
+  if (type == 'number' || type == 'string' || type == 'boolean' ||
+      type == 'null' || type == 'undefined') {
+    return thing;
+  }
+  if (type == 'array') {
+    goog.asserts.assertArray(thing);
+    return goog.array.map(thing, jspb.debug.dump_);
+  }
+  var message = thing;  // Copy because we don't want type inference on thing.
+  goog.asserts.assert(message instanceof jspb.Message,
+      'Only messages expected: ' + thing);
+  var ctor = message.constructor;
+  var messageName = ctor.name || ctor.displayName;
+  var object = {
+    '$name': messageName
+  };
+  for (var name in ctor.prototype) {
+    var match = /^get([A-Z]\w*)/.exec(name);
+    if (match && name != 'getExtension' &&
+        name != 'getJsPbMessageId') {
+      var val = thing[name]();
+      if (val != null) {
+        object[jspb.debug.formatFieldName_(match[1])] = jspb.debug.dump_(val);
+      }
+    }
+  }
+  if (COMPILED && thing['extensionObject_']) {
+    object['$extensions'] = 'Recursive dumping of extensions not supported ' +
+        'in compiled code. Switch to uncompiled or dump extension object ' +
+        'directly';
+    return object;
+  }
+  var extensionsObject;
+  for (var id in ctor['extensions']) {
+    if (/^\d+$/.test(id)) {
+      var ext = ctor['extensions'][id];
+      var extVal = thing.getExtension(ext);
+      var fieldName = goog.object.getKeys(ext.fieldName)[0];
+      if (extVal != null) {
+        if (!extensionsObject) {
+          extensionsObject = object['$extensions'] = {};
+        }
+        extensionsObject[jspb.debug.formatFieldName_(fieldName)] =
+            jspb.debug.dump_(extVal);
+      }
+    }
+  }
+  return object;
+};
+
+
+/**
+ * Formats a field name for output as camelCase.
+ *
+ * @param {string} name Name of the field.
+ * @return {string}
+ * @private
+ */
+jspb.debug.formatFieldName_ = function(name) {
+  // Name may be in TitleCase.
+  return name.replace(/^[A-Z]/, function(c) {
+    return c.toLowerCase();
+  });
+};
diff --git a/js/debug_test.js b/js/debug_test.js
new file mode 100644
index 00000000..615fc7c6
--- /dev/null
+++ b/js/debug_test.js
@@ -0,0 +1,101 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+goog.setTestOnly();
+
+goog.require('goog.testing.asserts');
+goog.require('jspb.debug');
+goog.require('proto.jspb.test.HasExtensions');
+goog.require('proto.jspb.test.IsExtension');
+goog.require('proto.jspb.test.Simple1');
+
+
+
+describe('debugTest', function() {
+  it('testSimple1', function() {
+    if (COMPILED) {
+      return;
+    }
+    var message = new proto.jspb.test.Simple1();
+    message.setAString('foo');
+    assertObjectEquals({
+      $name: 'proto.jspb.test.Simple1',
+      'aString': 'foo',
+      'aRepeatedStringList': []
+    }, jspb.debug.dump(message));
+
+    message.setABoolean(true);
+    message.setARepeatedStringList(['1', '2']);
+
+    assertObjectEquals({
+      $name: 'proto.jspb.test.Simple1',
+      'aString': 'foo',
+      'aRepeatedStringList': ['1', '2'],
+      'aBoolean': true
+    }, jspb.debug.dump(message));
+
+    message.setAString(undefined);
+
+    assertObjectEquals({
+      $name: 'proto.jspb.test.Simple1',
+      'aRepeatedStringList': ['1', '2'],
+      'aBoolean': true
+    }, jspb.debug.dump(message));
+  });
+
+
+  it('testExtensions', function() {
+    if (COMPILED) {
+      return;
+    }
+    var extension = new proto.jspb.test.IsExtension();
+    extension.setExt1('ext1field');
+    var extendable = new proto.jspb.test.HasExtensions();
+    extendable.setStr1('v1');
+    extendable.setStr2('v2');
+    extendable.setStr3('v3');
+    extendable.setExtension(proto.jspb.test.IsExtension.extField, extension);
+
+    assertObjectEquals({
+      '$name': 'proto.jspb.test.HasExtensions',
+      'str1': 'v1',
+      'str2': 'v2',
+      'str3': 'v3',
+      '$extensions': {
+        'extField': {
+          '$name': 'proto.jspb.test.IsExtension',
+          'ext1': 'ext1field'
+        },
+        'repeatedSimpleList': []
+      }
+    }, jspb.debug.dump(extendable));
+  });
+
+});
diff --git a/js/message.js b/js/message.js
new file mode 100644
index 00000000..cef9aefd
--- /dev/null
+++ b/js/message.js
@@ -0,0 +1,1125 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Definition of jspb.Message.
+ *
+ * @author mwr@google.com (Mark Rawling)
+ */
+
+goog.provide('jspb.ExtensionFieldInfo');
+goog.provide('jspb.Message');
+
+goog.require('goog.array');
+goog.require('goog.asserts');
+goog.require('goog.json');
+goog.require('goog.object');
+
+// Not needed in compilation units that have no protos with xids.
+goog.forwardDeclare('xid.String');
+
+
+
+/**
+ * Stores information for a single extension field.
+ *
+ * For example, an extension field defined like so:
+ *
+ *     extend BaseMessage {
+ *       optional MyMessage my_field = 123;
+ *     }
+ *
+ * will result in an ExtensionFieldInfo object with these properties:
+ *
+ *     {
+ *       fieldIndex: 123,
+ *       fieldName: {my_field_renamed: 0},
+ *       ctor: proto.example.MyMessage,
+ *       toObjectFn: proto.example.MyMessage.toObject,
+ *       isRepeated: 0
+ *     }
+ *
+ * We include `toObjectFn` to allow the JSCompiler to perform dead-code removal
+ * on unused toObject() methods.
+ *
+ * If an extension field is primitive, ctor and toObjectFn will be null.
+ * isRepeated should be 0 or 1.
+ *
+ * binary{Reader,Writer}Fn and (if message type) binaryMessageSerializeFn are
+ * always provided. binaryReaderFn and binaryWriterFn are references to the
+ * appropriate methods on BinaryReader/BinaryWriter to read/write the value of
+ * this extension, and binaryMessageSerializeFn is a reference to the message
+ * class's .serializeBinary method, if available.
+ *
+ * @param {number} fieldNumber
+ * @param {Object} fieldName This has the extension field name as a property.
+ * @param {?function(new: jspb.Message, Array=)} ctor
+ * @param {?function((boolean|undefined),!jspb.Message):!Object} toObjectFn
+ * @param {number} isRepeated
+ * @param {?function(number,?)=} opt_binaryReaderFn
+ * @param {?function(number,?)|function(number,?,?,?,?,?)=} opt_binaryWriterFn
+ * @param {?function(?,?)=} opt_binaryMessageSerializeFn
+ * @param {?function(?,?)=} opt_binaryMessageDeserializeFn
+ * @param {?boolean=} opt_isPacked
+ * @constructor
+ * @struct
+ * @template T
+ */
+jspb.ExtensionFieldInfo = function(fieldNumber, fieldName, ctor, toObjectFn,
+    isRepeated, opt_binaryReaderFn, opt_binaryWriterFn,
+    opt_binaryMessageSerializeFn, opt_binaryMessageDeserializeFn,
+    opt_isPacked) {
+  /** @const */
+  this.fieldIndex = fieldNumber;
+  /** @const */
+  this.fieldName = fieldName;
+  /** @const */
+  this.ctor = ctor;
+  /** @const */
+  this.toObjectFn = toObjectFn;
+  /** @const */
+  this.binaryReaderFn = opt_binaryReaderFn;
+  /** @const */
+  this.binaryWriterFn = opt_binaryWriterFn;
+  /** @const */
+  this.binaryMessageSerializeFn = opt_binaryMessageSerializeFn;
+  /** @const */
+  this.binaryMessageDeserializeFn = opt_binaryMessageDeserializeFn;
+  /** @const */
+  this.isRepeated = isRepeated;
+  /** @const */
+  this.isPacked = opt_isPacked;
+};
+
+
+/**
+ * Base class for all JsPb messages.
+ * @constructor
+ * @struct
+ */
+jspb.Message = function() {
+};
+
+
+/**
+ * @define {boolean} Whether to generate toObject methods for objects. Turn
+ *     this off, if you do not want toObject to be ever used in your project.
+ *     When turning off this flag, consider adding a conformance test that bans
+ *     calling toObject. Enabling this will disable the JSCompiler's ability to
+ *     dead code eliminate fields used in protocol buffers that are never used
+ *     in an application.
+ */
+goog.define('jspb.Message.GENERATE_TO_OBJECT', true);
+
+
+/**
+ * @define {boolean} Whether to generate fromObject methods for objects. Turn
+ *     this off, if you do not want fromObject to be ever used in your project.
+ *     When turning off this flag, consider adding a conformance test that bans
+ *     calling fromObject. Enabling this might disable the JSCompiler's ability
+ *     to dead code eliminate fields used in protocol buffers that are never
+ *     used in an application.
+ *     NOTE: By default no protos actually have a fromObject method. You need to
+ *     add the jspb.generate_from_object options to the proto definition to
+ *     activate the feature.
+ *     By default this is enabled for test code only.
+ */
+goog.define('jspb.Message.GENERATE_FROM_OBJECT', !goog.DISALLOW_TEST_ONLY_CODE);
+
+
+/**
+ * @define {boolean} Turning on this flag does NOT change the behavior of JSPB
+ *     and only affects private internal state. It may, however, break some
+ *     tests that use naive deeply-equals algorithms, because using a proto
+ *     mutates its internal state.
+ *     Projects are advised to turn this flag always on.
+ */
+goog.define('jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS', COMPILED);
+// TODO(b/19419436) Turn this on by default.
+
+
+/**
+ * The internal data array.
+ * @type {!Array}
+ * @protected
+ */
+jspb.Message.prototype.array;
+
+
+/**
+ * Wrappers are the constructed instances of message-type fields. They are built
+ * on demand from the raw array data. Includes message fields, repeated message
+ * fields and extension message fields. Indexed by field number.
+ * @type {Object}
+ * @private
+ */
+jspb.Message.prototype.wrappers_;
+
+
+/**
+ * The object that contains extension fields, if any. This is an object that
+ * maps from a proto field number to the field's value.
+ * @type {Object}
+ * @private
+ */
+jspb.Message.prototype.extensionObject_;
+
+
+/**
+ * Non-extension fields with a field number at or above the pivot are
+ * stored in the extension object (in addition to all extension fields).
+ * @type {number}
+ * @private
+ */
+jspb.Message.prototype.pivot_;
+
+
+/**
+ * The JsPb message_id of this proto.
+ * @type {string|undefined} the message id or undefined if this message
+ *     has no id.
+ * @private
+ */
+jspb.Message.prototype.messageId_;
+
+
+/**
+ * The xid of this proto type (The same for all instances of a proto). Provides
+ * a way to identify a proto by stable obfuscated name.
+ * @see {xid}.
+ * Available if {@link jspb.generate_xid} is added as a Message option to
+ * a protocol buffer.
+ * @const {!xid.String|undefined} The xid or undefined if message is
+ *     annotated to generate the xid.
+ */
+jspb.Message.prototype.messageXid;
+
+
+
+/**
+ * Returns the JsPb message_id of this proto.
+ * @return {string|undefined} the message id or undefined if this message
+ *     has no id.
+ */
+jspb.Message.prototype.getJsPbMessageId = function() {
+  return this.messageId_;
+};
+
+
+/**
+ * An offset applied to lookups into this.array to account for the presence or
+ * absence of a messageId at position 0. For response messages, this will be 0.
+ * Otherwise, it will be -1 so that the first array position is not wasted.
+ * @type {number}
+ * @private
+ */
+jspb.Message.prototype.arrayIndexOffset_;
+
+
+/**
+ * Returns the index into msg.array at which the proto field with tag number
+ * fieldNumber will be located.
+ * @param {!jspb.Message} msg Message for which we're calculating an index.
+ * @param {number} fieldNumber The field number.
+ * @return {number} The index.
+ * @private
+ */
+jspb.Message.getIndex_ = function(msg, fieldNumber) {
+  return fieldNumber + msg.arrayIndexOffset_;
+};
+
+
+/**
+ * Initializes a JsPb Message.
+ * @param {!jspb.Message} msg The JsPb proto to modify.
+ * @param {Array|undefined} data An initial data array.
+ * @param {string|number} messageId For response messages, the message id or ''
+ *     if no message id is specified. For non-response messages, 0.
+ * @param {number} suggestedPivot The field number at which to start putting
+ *     fields into the extension object. This is only used if data does not
+ *     contain an extension object already. -1 if no extension object is
+ *     required for this message type.
+ * @param {Array<number>} repeatedFields The message's repeated fields.
+ * @param {Array<!Array<number>>=} opt_oneofFields The fields belonging to
+ *     each of the message's oneof unions.
+ * @protected
+ */
+jspb.Message.initialize = function(
+    msg, data, messageId, suggestedPivot, repeatedFields, opt_oneofFields) {
+  msg.wrappers_ = jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS ? null : {};
+  if (!data) {
+    data = messageId ? [messageId] : [];
+  }
+  msg.messageId_ = messageId ? String(messageId) : undefined;
+  // If the messageId is 0, this message is not a response message, so we shift
+  // array indices down by 1 so as not to waste the first position in the array,
+  // which would otherwise go unused.
+  msg.arrayIndexOffset_ = messageId === 0 ? -1 : 0;
+  msg.array = data;
+  jspb.Message.materializeExtensionObject_(msg, suggestedPivot);
+  if (repeatedFields) {
+    for (var i = 0; i < repeatedFields.length; i++) {
+      var fieldNumber = repeatedFields[i];
+      if (fieldNumber < msg.pivot_) {
+        var index = jspb.Message.getIndex_(msg, fieldNumber);
+        msg.array[index] = msg.array[index] ||
+            (jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS ?
+                jspb.Message.EMPTY_LIST_SENTINEL_ :
+                []);
+      } else {
+        msg.extensionObject_[fieldNumber] =
+            msg.extensionObject_[fieldNumber] ||
+            (jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS ?
+                jspb.Message.EMPTY_LIST_SENTINEL_ :
+                []);
+      }
+    }
+  }
+
+  if (opt_oneofFields && opt_oneofFields.length) {
+    // Compute the oneof case for each union. This ensures only one value is
+    // set in the union.
+    goog.array.forEach(
+        opt_oneofFields, goog.partial(jspb.Message.computeOneofCase, msg));
+  }
+};
+
+
+/**
+ * Used to mark empty repeated fields. Serializes to null when serialized
+ * to JSON.
+ * When reading a repeated field readers must check the return value against
+ * this value and return and replace it with a new empty array if it is
+ * present.
+ * @private @const {!Object}
+ */
+jspb.Message.EMPTY_LIST_SENTINEL_ = goog.DEBUG && Object.freeze ?
+    Object.freeze([]) :
+    [];
+
+
+/**
+ * Ensures that the array contains an extension object if necessary.
+ * If the array contains an extension object in its last position, then the
+ * object is kept in place and its position is used as the pivot.  If not, then
+ * create an extension object using suggestedPivot.  If suggestedPivot is -1,
+ * we don't have an extension object at all, in which case all fields are stored
+ * in the array.
+ * @param {!jspb.Message} msg The JsPb proto to modify.
+ * @param {number} suggestedPivot See description for initialize().
+ * @private
+ */
+jspb.Message.materializeExtensionObject_ = function(msg, suggestedPivot) {
+  if (msg.array.length) {
+    var foundIndex = msg.array.length - 1;
+    var obj = msg.array[foundIndex];
+    // Normal fields are never objects, so we can be sure that if we find an
+    // object here, then it's the extension object. However, we must ensure that
+    // the object is not an array, since arrays are valid field values.
+    // NOTE(lukestebbing): We avoid looking at .length to avoid a JIT bug
+    // in Safari on iOS 8. See the description of CL/86511464 for details.
+    if (obj && typeof obj == 'object' && !goog.isArray(obj)) {
+      msg.pivot_ = foundIndex - msg.arrayIndexOffset_;
+      msg.extensionObject_ = obj;
+      return;
+    }
+  }
+  // This complexity exists because we keep all extension fields in the
+  // extensionObject_ regardless of proto field number. Changing this would
+  // simplify the code here, but it would require changing the serialization
+  // format from the server, which is not backwards compatible.
+  // TODO(jshneier): Should we just treat extension fields the same as
+  // non-extension fields, and select whether they appear in the object or in
+  // the array purely based on tag number? This would allow simplifying all the
+  // get/setExtension logic, but it would require the breaking change described
+  // above.
+  if (suggestedPivot > -1) {
+    msg.pivot_ = suggestedPivot;
+    var pivotIndex = jspb.Message.getIndex_(msg, suggestedPivot);
+    if (!jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS) {
+      msg.extensionObject_ = msg.array[pivotIndex] = {};
+    } else {
+      // Initialize to null to avoid changing the shape of the proto when it
+      // gets eventually set.
+      msg.extensionObject_ = null;
+    }
+  } else {
+    msg.pivot_ = Number.MAX_VALUE;
+  }
+};
+
+
+/**
+ * Creates an empty extensionObject_ if non exists.
+ * @param {!jspb.Message} msg The JsPb proto to modify.
+ * @private
+ */
+jspb.Message.maybeInitEmptyExtensionObject_ = function(msg) {
+  var pivotIndex = jspb.Message.getIndex_(msg, msg.pivot_);
+  if (!msg.array[pivotIndex]) {
+    msg.extensionObject_ = msg.array[pivotIndex] = {};
+  }
+};
+
+
+/**
+ * Converts a JsPb repeated message field into an object list.
+ * @param {!Array<T>} field The repeated message field to be
+ *     converted.
+ * @param {?function(boolean=): Object|
+ *     function((boolean|undefined),T): Object} toObjectFn The toObject
+ *     function for this field.  We need to pass this for effective dead code
+ *     removal.
+ * @param {boolean=} opt_includeInstance Whether to include the JSPB instance
+ *     for transitional soy proto support: http://goto/soy-param-migration
+ * @return {!Array<Object>} An array of converted message objects.
+ * @template T
+ */
+jspb.Message.toObjectList = function(field, toObjectFn, opt_includeInstance) {
+  // Not using goog.array.map in the generated code to keep it small.
+  // And not using it here to avoid a function call.
+  var result = [];
+  for (var i = 0; i < field.length; i++) {
+    result[i] = toObjectFn.call(field[i], opt_includeInstance,
+      /** @type {!jspb.Message} */ (field[i]));
+  }
+  return result;
+};
+
+
+/**
+ * Adds a proto's extension data to a Soy rendering object.
+ * @param {!jspb.Message} proto The proto whose extensions to convert.
+ * @param {!Object} obj The Soy object to add converted extension data to.
+ * @param {!Object} extensions The proto class' registered extensions.
+ * @param {function(jspb.ExtensionFieldInfo) : *} getExtensionFn The proto
+ *     class' getExtension function. Passed for effective dead code removal.
+ * @param {boolean=} opt_includeInstance Whether to include the JSPB instance
+ *     for transitional soy proto support: http://goto/soy-param-migration
+ */
+jspb.Message.toObjectExtension = function(proto, obj, extensions,
+    getExtensionFn, opt_includeInstance) {
+  for (var fieldNumber in extensions) {
+    var fieldInfo = extensions[fieldNumber];
+    var value = getExtensionFn.call(proto, fieldInfo);
+    if (value) {
+      for (var name in fieldInfo.fieldName) {
+        if (fieldInfo.fieldName.hasOwnProperty(name)) {
+          break; // the compiled field name
+        }
+      }
+      if (!fieldInfo.toObjectFn) {
+        obj[name] = value;
+      } else {
+        if (fieldInfo.isRepeated) {
+          obj[name] = jspb.Message.toObjectList(
+              /** @type {!Array<jspb.Message>} */ (value),
+              fieldInfo.toObjectFn, opt_includeInstance);
+        } else {
+          obj[name] = fieldInfo.toObjectFn(opt_includeInstance, value);
+        }
+      }
+    }
+  }
+};
+
+
+/**
+ * Writes a proto's extension data to a binary-format output stream.
+ * @param {!jspb.Message} proto The proto whose extensions to convert.
+ * @param {*} writer The binary-format writer to write to.
+ * @param {!Object} extensions The proto class' registered extensions.
+ * @param {function(jspb.ExtensionFieldInfo) : *} getExtensionFn The proto
+ *     class' getExtension function. Passed for effective dead code removal.
+ */
+jspb.Message.serializeBinaryExtensions = function(proto, writer, extensions,
+    getExtensionFn) {
+  for (var fieldNumber in extensions) {
+    var fieldInfo = extensions[fieldNumber];
+    // The old codegen doesn't add the extra fields to ExtensionFieldInfo, so we
+    // need to gracefully error-out here rather than produce a null dereference
+    // below.
+    if (!fieldInfo.binaryWriterFn) {
+      throw new Error('Message extension present that was generated ' +
+                      'without binary serialization support');
+    }
+    var value = getExtensionFn.call(proto, fieldInfo);
+    if (value) {
+      if (fieldInfo.ctor) {  // is this a message type?
+        // If the message type of the extension was generated without binary
+        // support, there may not be a binary message serializer function, and
+        // we can't know when we codegen the extending message that the extended
+        // message may require binary support, so we can *only* catch this error
+        // here, at runtime (and this decoupled codegen is the whole point of
+        // extensions!).
+        if (fieldInfo.binaryMessageSerializeFn) {
+          fieldInfo.binaryWriterFn.call(writer, fieldInfo.fieldIndex,
+              value, fieldInfo.binaryMessageSerializeFn);
+        } else {
+          throw new Error('Message extension present holding submessage ' +
+                          'without binary support enabled, and message is ' +
+                          'being serialized to binary format');
+        }
+      } else {
+        fieldInfo.binaryWriterFn.call(writer, fieldInfo.fieldIndex, value);
+      }
+    }
+  }
+};
+
+
+/**
+ * Reads an extension field from the given reader and, if a valid extension,
+ * sets the extension value.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {{skipField:function(),getFieldNumber:function():number}} reader
+ * @param {!Object} extensions The extensions object.
+ * @param {function(jspb.ExtensionFieldInfo)} getExtensionFn
+ * @param {function(jspb.ExtensionFieldInfo, ?)} setExtensionFn
+ */
+jspb.Message.readBinaryExtension = function(msg, reader, extensions,
+    getExtensionFn, setExtensionFn) {
+  var fieldInfo = extensions[reader.getFieldNumber()];
+  if (!fieldInfo) {
+    reader.skipField();
+    return;
+  }
+  if (!fieldInfo.binaryReaderFn) {
+    throw new Error('Deserializing extension whose generated code does not ' +
+                    'support binary format');
+  }
+
+  var value;
+  if (fieldInfo.ctor) {
+    // Message type.
+    value = new fieldInfo.ctor();
+    fieldInfo.binaryReaderFn.call(
+        reader, value, fieldInfo.binaryMessageDeserializeFn);
+  } else {
+    // All other types.
+    value = fieldInfo.binaryReaderFn.call(reader);
+  }
+
+  if (fieldInfo.isRepeated && !fieldInfo.isPacked) {
+    var currentList = getExtensionFn.call(msg, fieldInfo);
+    if (!currentList) {
+      setExtensionFn.call(msg, fieldInfo, [value]);
+    } else {
+      currentList.push(value);
+    }
+  } else {
+    setExtensionFn.call(msg, fieldInfo, value);
+  }
+};
+
+
+/**
+ * Gets the value of a non-extension field.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @return {string|number|boolean|Uint8Array|Array|null|undefined}
+ * The field's value.
+ * @protected
+ */
+jspb.Message.getField = function(msg, fieldNumber) {
+  if (fieldNumber < msg.pivot_) {
+    var index = jspb.Message.getIndex_(msg, fieldNumber);
+    var val = msg.array[index];
+    if (val === jspb.Message.EMPTY_LIST_SENTINEL_) {
+      return msg.array[index] = [];
+    }
+    return val;
+  } else {
+    var val = msg.extensionObject_[fieldNumber];
+    if (val === jspb.Message.EMPTY_LIST_SENTINEL_) {
+      return msg.extensionObject_[fieldNumber] = [];
+    }
+    return val;
+  }
+};
+
+
+/**
+ * Gets the value of a non-extension primitive field, with proto3 (non-nullable
+ * primitives) semantics. Returns `defaultValue` if the field is not otherwise
+ * set.
+ * @template T
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {T} defaultValue The default value.
+ * @return {T} The field's value.
+ * @protected
+ */
+jspb.Message.getFieldProto3 = function(msg, fieldNumber, defaultValue) {
+  var value = jspb.Message.getField(msg, fieldNumber);
+  if (value == null) {
+    return defaultValue;
+  } else {
+    return value;
+  }
+};
+
+
+/**
+ * Sets the value of a non-extension field.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {string|number|boolean|Uint8Array|Array|undefined} value New value
+ * @protected
+ */
+jspb.Message.setField = function(msg, fieldNumber, value) {
+  if (fieldNumber < msg.pivot_) {
+    msg.array[jspb.Message.getIndex_(msg, fieldNumber)] = value;
+  } else {
+    msg.extensionObject_[fieldNumber] = value;
+  }
+};
+
+
+/**
+ * Sets the value of a field in a oneof union and clears all other fields in
+ * the union.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {!Array<number>} oneof The fields belonging to the union.
+ * @param {string|number|boolean|Uint8Array|Array|undefined} value New value
+ * @protected
+ */
+jspb.Message.setOneofField = function(msg, fieldNumber, oneof, value) {
+  var currentCase = jspb.Message.computeOneofCase(msg, oneof);
+  if (currentCase && currentCase !== fieldNumber && value !== undefined) {
+    if (msg.wrappers_ && currentCase in msg.wrappers_) {
+      msg.wrappers_[currentCase] = undefined;
+    }
+    jspb.Message.setField(msg, currentCase, undefined);
+  }
+  jspb.Message.setField(msg, fieldNumber, value);
+};
+
+
+/**
+ * Computes the selection in a oneof group for the given message, ensuring
+ * only one field is set in the process.
+ *
+ * According to the protobuf language guide (
+ * https://developers.google.com/protocol-buffers/docs/proto#oneof), "if the
+ * parser encounters multiple members of the same oneof on the wire, only the
+ * last member seen is used in the parsed message." Since JSPB serializes
+ * messages to a JSON array, the "last member seen" will always be the field
+ * with the greatest field number (directly corresponding to the greatest
+ * array index).
+ *
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {!Array<number>} oneof The field numbers belonging to the union.
+ * @return {number} The field number currently set in the union, or 0 if none.
+ * @protected
+ */
+jspb.Message.computeOneofCase = function(msg, oneof) {
+  var oneofField;
+  var oneofValue;
+
+  goog.array.forEach(oneof, function(fieldNumber) {
+    var value = jspb.Message.getField(msg, fieldNumber);
+    if (goog.isDefAndNotNull(value)) {
+      oneofField = fieldNumber;
+      oneofValue = value;
+      jspb.Message.setField(msg, fieldNumber, undefined);
+    }
+  });
+
+  if (oneofField) {
+    // NB: We know the value is unique, so we can call jspb.Message.setField
+    // directly instead of jpsb.Message.setOneofField. Also, setOneofField
+    // calls this function.
+    jspb.Message.setField(msg, oneofField, oneofValue);
+    return oneofField;
+  }
+
+  return 0;
+};
+
+
+/**
+ * Gets and wraps a proto field on access.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {function(new:jspb.Message, Array)} ctor Constructor for the field.
+ * @param {number} fieldNumber The field number.
+ * @param {number=} opt_required True (1) if this is a required field.
+ * @return {jspb.Message} The field as a jspb proto.
+ * @protected
+ */
+jspb.Message.getWrapperField = function(msg, ctor, fieldNumber, opt_required) {
+  // TODO(mwr): Consider copying data and/or arrays.
+  if (!msg.wrappers_) {
+    msg.wrappers_ = {};
+  }
+  if (!msg.wrappers_[fieldNumber]) {
+    var data = /** @type {Array} */ (jspb.Message.getField(msg, fieldNumber));
+    if (opt_required || data) {
+      // TODO(mwr): Remove existence test for always valid default protos.
+      msg.wrappers_[fieldNumber] = new ctor(data);
+    }
+  }
+  return /** @type {jspb.Message} */ (msg.wrappers_[fieldNumber]);
+};
+
+
+/**
+ * Gets and wraps a repeated proto field on access.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {function(new:jspb.Message, Array)} ctor Constructor for the field.
+ * @param {number} fieldNumber The field number.
+ * @return {Array<!jspb.Message>} The repeated field as an array of protos.
+ * @protected
+ */
+jspb.Message.getRepeatedWrapperField = function(msg, ctor, fieldNumber) {
+  if (!msg.wrappers_) {
+    msg.wrappers_ = {};
+  }
+  if (!msg.wrappers_[fieldNumber]) {
+    var data = jspb.Message.getField(msg, fieldNumber);
+    for (var wrappers = [], i = 0; i < data.length; i++) {
+      wrappers[i] = new ctor(data[i]);
+    }
+    msg.wrappers_[fieldNumber] = wrappers;
+  }
+  var val = msg.wrappers_[fieldNumber];
+  if (val == jspb.Message.EMPTY_LIST_SENTINEL_) {
+    val = msg.wrappers_[fieldNumber] = [];
+  }
+  return /** @type {Array<!jspb.Message>} */ (val);
+};
+
+
+/**
+ * Sets a proto field and syncs it to the backing array.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {jspb.Message|undefined} value A new value for this proto field.
+ * @protected
+ */
+jspb.Message.setWrapperField = function(msg, fieldNumber, value) {
+  if (!msg.wrappers_) {
+    msg.wrappers_ = {};
+  }
+  var data = value ? value.toArray() : value;
+  msg.wrappers_[fieldNumber] = value;
+  jspb.Message.setField(msg, fieldNumber, data);
+};
+
+
+/**
+ * Sets a proto field in a oneof union and syncs it to the backing array.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {!Array<number>} oneof The fields belonging to the union.
+ * @param {jspb.Message|undefined} value A new value for this proto field.
+ * @protected
+ */
+jspb.Message.setOneofWrapperField = function(msg, fieldNumber, oneof, value) {
+  if (!msg.wrappers_) {
+    msg.wrappers_ = {};
+  }
+  var data = value ? value.toArray() : value;
+  msg.wrappers_[fieldNumber] = value;
+  jspb.Message.setOneofField(msg, fieldNumber, oneof, data);
+};
+
+
+/**
+ * Sets a repeated proto field and syncs it to the backing array.
+ * @param {!jspb.Message} msg A jspb proto.
+ * @param {number} fieldNumber The field number.
+ * @param {Array<!jspb.Message>|undefined} value An array of protos.
+ * @protected
+ */
+jspb.Message.setRepeatedWrapperField = function(msg, fieldNumber, value) {
+  if (!msg.wrappers_) {
+    msg.wrappers_ = {};
+  }
+  value = value || [];
+  for (var data = [], i = 0; i < value.length; i++) {
+    data[i] = value[i].toArray();
+  }
+  msg.wrappers_[fieldNumber] = value;
+  jspb.Message.setField(msg, fieldNumber, data);
+};
+
+
+/**
+ * Converts a JsPb repeated message field into a map. The map will contain
+ * protos unless an optional toObject function is given, in which case it will
+ * contain objects suitable for Soy rendering.
+ * @param {!Array<T>} field The repeated message field to be
+ *     converted.
+ * @param {function() : string?} mapKeyGetterFn The function to get the key of
+ *     the map.
+ * @param {?function(boolean=): Object|
+ *     function((boolean|undefined),T): Object} opt_toObjectFn The
+ *     toObject function for this field. We need to pass this for effective
+ *     dead code removal.
+ * @param {boolean=} opt_includeInstance Whether to include the JSPB instance
+ *     for transitional soy proto support: http://goto/soy-param-migration
+ * @return {!Object.<string, Object>} A map of proto or Soy objects.
+ * @template T
+ */
+jspb.Message.toMap = function(
+    field, mapKeyGetterFn, opt_toObjectFn, opt_includeInstance) {
+  var result = {};
+  for (var i = 0; i < field.length; i++) {
+    result[mapKeyGetterFn.call(field[i])] = opt_toObjectFn ?
+        opt_toObjectFn.call(field[i], opt_includeInstance,
+            /** @type {!jspb.Message} */ (field[i])) : field[i];
+  }
+  return result;
+};
+
+
+/**
+ * Returns the internal array of this proto.
+ * <p>Note: If you use this array to construct a second proto, the content
+ * would then be partially shared between the two protos.
+ * @return {!Array} The proto represented as an array.
+ */
+jspb.Message.prototype.toArray = function() {
+  return this.array;
+};
+
+
+
+
+/**
+ * Creates a string representation of the internal data array of this proto.
+ * <p>NOTE: This string is *not* suitable for use in server requests.
+ * @return {string} A string representation of this proto.
+ * @override
+ */
+jspb.Message.prototype.toString = function() {
+  return this.array.toString();
+};
+
+
+/**
+ * Gets the value of the extension field from the extended object.
+ * @param {jspb.ExtensionFieldInfo.<T>} fieldInfo Specifies the field to get.
+ * @return {T} The value of the field.
+ * @template T
+ */
+jspb.Message.prototype.getExtension = function(fieldInfo) {
+  if (!this.extensionObject_) {
+    return undefined;
+  }
+  if (!this.wrappers_) {
+    this.wrappers_ = {};
+  }
+  var fieldNumber = fieldInfo.fieldIndex;
+  if (fieldInfo.isRepeated) {
+    if (fieldInfo.ctor) {
+      if (!this.wrappers_[fieldNumber]) {
+        this.wrappers_[fieldNumber] =
+            goog.array.map(this.extensionObject_[fieldNumber] || [],
+                function(arr) {
+                  return new fieldInfo.ctor(arr);
+                });
+      }
+      return this.wrappers_[fieldNumber];
+    } else {
+      return this.extensionObject_[fieldNumber];
+    }
+  } else {
+    if (fieldInfo.ctor) {
+      if (!this.wrappers_[fieldNumber] && this.extensionObject_[fieldNumber]) {
+        this.wrappers_[fieldNumber] = new fieldInfo.ctor(
+            /** @type {Array|undefined} */ (
+                this.extensionObject_[fieldNumber]));
+      }
+      return this.wrappers_[fieldNumber];
+    } else {
+      return this.extensionObject_[fieldNumber];
+    }
+  }
+};
+
+
+/**
+ * Sets the value of the extension field in the extended object.
+ * @param {jspb.ExtensionFieldInfo} fieldInfo Specifies the field to set.
+ * @param {jspb.Message|string|number|boolean|Array} value The value to set.
+ */
+jspb.Message.prototype.setExtension = function(fieldInfo, value) {
+  if (!this.wrappers_) {
+    this.wrappers_ = {};
+  }
+  jspb.Message.maybeInitEmptyExtensionObject_(this);
+  var fieldNumber = fieldInfo.fieldIndex;
+  if (fieldInfo.isRepeated) {
+    value = value || [];
+    if (fieldInfo.ctor) {
+      this.wrappers_[fieldNumber] = value;
+      this.extensionObject_[fieldNumber] = goog.array.map(
+          /** @type {Array<jspb.Message>} */ (value), function(msg) {
+        return msg.toArray();
+      });
+    } else {
+      this.extensionObject_[fieldNumber] = value;
+    }
+  } else {
+    if (fieldInfo.ctor) {
+      this.wrappers_[fieldNumber] = value;
+      this.extensionObject_[fieldNumber] = value ? value.toArray() : value;
+    } else {
+      this.extensionObject_[fieldNumber] = value;
+    }
+  }
+};
+
+
+/**
+ * Creates a difference object between two messages.
+ *
+ * The result will contain the top-level fields of m2 that differ from those of
+ * m1 at any level of nesting. No data is cloned, the result object will
+ * share its top-level elements with m2 (but not with m1).
+ *
+ * Note that repeated fields should not have null/undefined elements, but if
+ * they do, this operation will treat repeated fields of different length as
+ * the same if the only difference between them is due to trailing
+ * null/undefined values.
+ *
+ * @param {!jspb.Message} m1 The first message object.
+ * @param {!jspb.Message} m2 The second message object.
+ * @return {!jspb.Message} The difference returned as a proto message.
+ *     Note that the returned message may be missing required fields. This is
+ *     currently tolerated in Js, but would cause an error if you tried to
+ *     send such a proto to the server. You can access the raw difference
+ *     array with result.toArray().
+ * @throws {Error} If the messages are responses with different types.
+ */
+jspb.Message.difference = function(m1, m2) {
+  if (!(m1 instanceof m2.constructor)) {
+    throw new Error('Messages have different types.');
+  }
+  var arr1 = m1.toArray();
+  var arr2 = m2.toArray();
+  var res = [];
+  var start = 0;
+  var length = arr1.length > arr2.length ? arr1.length : arr2.length;
+  if (m1.getJsPbMessageId()) {
+    res[0] = m1.getJsPbMessageId();
+    start = 1;
+  }
+  for (var i = start; i < length; i++) {
+    if (!jspb.Message.compareFields(arr1[i], arr2[i])) {
+      res[i] = arr2[i];
+    }
+  }
+  return new m1.constructor(res);
+};
+
+
+/**
+ * Tests whether two messages are equal.
+ * @param {jspb.Message|undefined} m1 The first message object.
+ * @param {jspb.Message|undefined} m2 The second message object.
+ * @return {boolean} true if both messages are null/undefined, or if both are
+ *     of the same type and have the same field values.
+ */
+jspb.Message.equals = function(m1, m2) {
+  return m1 == m2 || (!!(m1 && m2) && (m1 instanceof m2.constructor) &&
+      jspb.Message.compareFields(m1.toArray(), m2.toArray()));
+};
+
+
+/**
+ * Compares two message fields recursively.
+ * @param {*} field1 The first field.
+ * @param {*} field2 The second field.
+ * @return {boolean} true if the fields are null/undefined, or otherwise equal.
+ */
+jspb.Message.compareFields = function(field1, field2) {
+  if (goog.isObject(field1) && goog.isObject(field2)) {
+    var keys = {}, name, extensionObject1, extensionObject2;
+    for (name in field1) {
+      field1.hasOwnProperty(name) && (keys[name] = 0);
+    }
+    for (name in field2) {
+      field2.hasOwnProperty(name) && (keys[name] = 0);
+    }
+    for (name in keys) {
+      var val1 = field1[name], val2 = field2[name];
+      if (goog.isObject(val1) && !goog.isArray(val1)) {
+        if (extensionObject1 !== undefined) {
+          throw new Error('invalid jspb state');
+        }
+        extensionObject1 = goog.object.isEmpty(val1) ? undefined : val1;
+        val1 = undefined;
+      }
+      if (goog.isObject(val2) && !goog.isArray(val2)) {
+        if (extensionObject2 !== undefined) {
+          throw new Error('invalid jspb state');
+        }
+        extensionObject2 = goog.object.isEmpty(val2) ? undefined : val2;
+        val2 = undefined;
+      }
+      if (!jspb.Message.compareFields(val1, val2)) {
+        return false;
+      }
+    }
+    if (extensionObject1 || extensionObject2) {
+      return jspb.Message.compareFields(extensionObject1, extensionObject2);
+    }
+    return true;
+  }
+  // Primitive fields, null and undefined compare as equal.
+  // This also forces booleans and 0/1 to compare as equal to ensure
+  // compatibility with the jspb serializer.
+  return field1 == field2;
+};
+
+
+/**
+ * Static clone function. NOTE: A type-safe method called "cloneMessage" exists
+ * on each generated JsPb class. Do not call this function directly.
+ * @param {!jspb.Message} msg A message to clone.
+ * @return {!jspb.Message} A deep clone of the given message.
+ */
+jspb.Message.clone = function(msg) {
+  // Although we could include the wrappers, we leave them out here.
+  return jspb.Message.cloneMessage(msg);
+};
+
+
+/**
+ * @param {!jspb.Message} msg A message to clone.
+ * @return {!jspb.Message} A deep clone of the given message.
+ * @protected
+ */
+jspb.Message.cloneMessage = function(msg) {
+  // Although we could include the wrappers, we leave them out here.
+  return new msg.constructor(jspb.Message.clone_(msg.toArray()));
+};
+
+
+/**
+ * Takes 2 messages of the same type and copies the contents of the first
+ * message into the second. After this the 2 messages will equals in terms of
+ * value semantics but share no state. All data in the destination message will
+ * be overridden.
+ *
+ * @param {MESSAGE} fromMessage Message that will be copied into toMessage.
+ * @param {MESSAGE} toMessage Message which will receive a copy of fromMessage
+ *     as its contents.
+ * @template MESSAGE
+ */
+jspb.Message.copyInto = function(fromMessage, toMessage) {
+  goog.asserts.assertInstanceof(fromMessage, jspb.Message);
+  goog.asserts.assertInstanceof(toMessage, jspb.Message);
+  goog.asserts.assert(fromMessage.constructor == toMessage.constructor,
+      'Copy source and target message should have the same type.');
+  var copyOfFrom = jspb.Message.clone(fromMessage);
+
+  var to = toMessage.toArray();
+  var from = copyOfFrom.toArray();
+
+  // Empty destination in case it has more values at the end of the array.
+  to.length = 0;
+  // and then copy everything from the new to the existing message.
+  for (var i = 0; i < from.length; i++) {
+    to[i] = from[i];
+  }
+
+  // This is either null or empty for a fresh copy.
+  toMessage.wrappers_ = copyOfFrom.wrappers_;
+  // Just a reference into the shared array.
+  toMessage.extensionObject_ = copyOfFrom.extensionObject_;
+};
+
+
+/**
+ * Helper for cloning an internal JsPb object.
+ * @param {!Object} obj A JsPb object, eg, a field, to be cloned.
+ * @return {!Object} A clone of the input object.
+ * @private
+ */
+jspb.Message.clone_ = function(obj) {
+  var o;
+  if (goog.isArray(obj)) {
+    // Allocate array of correct size.
+    var clonedArray = new Array(obj.length);
+    // Use array iteration where possible because it is faster than for-in.
+    for (var i = 0; i < obj.length; i++) {
+      if ((o = obj[i]) != null) {
+        clonedArray[i] = typeof o == 'object' ? jspb.Message.clone_(o) : o;
+      }
+    }
+    return clonedArray;
+  }
+  var clone = {};
+  for (var key in obj) {
+    if ((o = obj[key]) != null) {
+      clone[key] = typeof o == 'object' ? jspb.Message.clone_(o) : o;
+    }
+  }
+  return clone;
+};
+
+
+/**
+ * Registers a JsPb message type id with its constructor.
+ * @param {string} id The id for this type of message.
+ * @param {Function} constructor The message constructor.
+ */
+jspb.Message.registerMessageType = function(id, constructor) {
+  jspb.Message.registry_[id] = constructor;
+  // This is needed so we can later access messageId directly on the contructor,
+  // otherwise it is not available due to 'property collapsing' by the compiler.
+  constructor.messageId = id;
+};
+
+
+/**
+ * The registry of message ids to message constructors.
+ * @private
+ */
+jspb.Message.registry_ = {};
+
+
+/**
+ * The extensions registered on MessageSet. This is a map of extension
+ * field number to field info object. This should be considered as a
+ * private API.
+ *
+ * This is similar to [jspb class name].extensions object for
+ * non-MessageSet. We special case MessageSet so that we do not need
+ * to goog.require MessageSet from classes that extends MessageSet.
+ *
+ * @type {!Object.<number, jspb.ExtensionFieldInfo>}
+ */
+jspb.Message.messageSetExtensions = {};
diff --git a/js/message_test.js b/js/message_test.js
new file mode 100644
index 00000000..5d3caaa0
--- /dev/null
+++ b/js/message_test.js
@@ -0,0 +1,970 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test suite is written using Jasmine -- see http://jasmine.github.io/
+
+goog.setTestOnly();
+
+goog.require('goog.json');
+goog.require('goog.testing.asserts');
+goog.require('jspb.Message');
+goog.require('proto.jspb.exttest.beta.floatingStrField');
+goog.require('proto.jspb.exttest.floatingMsgField');
+goog.require('proto.jspb.exttest.floatingMsgFieldTwo');
+goog.require('proto.jspb.test.CloneExtension');
+goog.require('proto.jspb.test.Complex');
+goog.require('proto.jspb.test.DefaultValues');
+goog.require('proto.jspb.test.Empty');
+goog.require('proto.jspb.test.EnumContainer');
+goog.require('proto.jspb.test.ExtensionMessage');
+goog.require('proto.jspb.test.floatingMsgField');
+goog.require('proto.jspb.test.floatingStrField');
+goog.require('proto.jspb.test.HasExtensions');
+goog.require('proto.jspb.test.IndirectExtension');
+goog.require('proto.jspb.test.IsExtension');
+goog.require('proto.jspb.test.OptionalFields');
+goog.require('proto.jspb.test.OuterEnum');
+goog.require('proto.jspb.test.simple1');
+goog.require('proto.jspb.test.Simple1');
+goog.require('proto.jspb.test.Simple2');
+goog.require('proto.jspb.test.SpecialCases');
+goog.require('proto.jspb.test.TestClone');
+goog.require('proto.jspb.test.TestExtensionsMessage');
+goog.require('proto.jspb.test.TestGroup');
+goog.require('proto.jspb.test.TestGroup1');
+goog.require('proto.jspb.test.TestMessageWithOneof');
+goog.require('proto.jspb.test.TestReservedNames');
+goog.require('proto.jspb.test.TestReservedNamesExtension');
+
+
+
+
+describe('Message test suite', function() {
+  it('testEmptyProto', function() {
+    var empty1 = new proto.jspb.test.Empty([]);
+    var empty2 = new proto.jspb.test.Empty([]);
+    assertObjectEquals({}, empty1.toObject());
+    assertObjectEquals('Message should not be corrupted:', empty2, empty1);
+  });
+
+  it('testTopLevelEnum', function() {
+    var response = new proto.jspb.test.EnumContainer([]);
+    response.setOuterEnum(proto.jspb.test.OuterEnum.FOO);
+    assertEquals(proto.jspb.test.OuterEnum.FOO, response.getOuterEnum());
+  });
+
+  it('testByteStrings', function() {
+    var data = new proto.jspb.test.DefaultValues([]);
+    data.setBytesField('some_bytes');
+    assertEquals('some_bytes', data.getBytesField());
+  });
+
+  it('testComplexConversion', function() {
+    var data1 = ['a',,, [, 11], [[, 22], [, 33]],, ['s1', 's2'],, 1];
+    var data2 = ['a',,, [, 11], [[, 22], [, 33]],, ['s1', 's2'],, 1];
+    var foo = new proto.jspb.test.Complex(data1);
+    var bar = new proto.jspb.test.Complex(data2);
+    var result = foo.toObject();
+    assertObjectEquals({
+      aString: 'a',
+      anOutOfOrderBool: 1,
+      aNestedMessage: {
+        anInt: 11
+      },
+      aRepeatedMessageList: [{anInt: 22}, {anInt: 33}],
+      aRepeatedStringList: ['s1', 's2']
+    }, result);
+
+    // Now test with the jspb instances included.
+    result = foo.toObject(true /* opt_includeInstance */);
+    assertObjectEquals({
+      aString: 'a',
+      anOutOfOrderBool: 1,
+      aNestedMessage: {
+        anInt: 11,
+        $jspbMessageInstance: foo.getANestedMessage()
+      },
+      aRepeatedMessageList: [
+        {anInt: 22, $jspbMessageInstance: foo.getARepeatedMessageList()[0]},
+        {anInt: 33, $jspbMessageInstance: foo.getARepeatedMessageList()[1]}
+      ],
+      aRepeatedStringList: ['s1', 's2'],
+      $jspbMessageInstance: foo
+    }, result);
+
+  });
+
+  it('testMissingFields', function() {
+    var foo = new proto.jspb.test.Complex([
+        undefined, undefined, undefined, [],
+        undefined, undefined, undefined, undefined]);
+    var bar = new proto.jspb.test.Complex([
+        undefined, undefined, undefined, [],
+        undefined, undefined, undefined, undefined]);
+    var result = foo.toObject();
+    assertObjectEquals({
+      aString: undefined,
+      anOutOfOrderBool: undefined,
+      aNestedMessage: {
+        anInt: undefined
+      },
+      // Note: JsPb converts undefined repeated fields to empty arrays.
+      aRepeatedMessageList: [],
+      aRepeatedStringList: []
+    }, result);
+
+  });
+
+  it('testSpecialCases', function() {
+    // Note: Some property names are reserved in JavaScript.
+    // These names are converted to the Js property named pb_<reserved_name>.
+    var special =
+        new proto.jspb.test.SpecialCases(['normal', 'default', 'function',
+        'var']);
+    var result = special.toObject();
+    assertObjectEquals({
+      normal: 'normal',
+      pb_default: 'default',
+      pb_function: 'function',
+      pb_var: 'var'
+    }, result);
+  });
+
+  it('testDefaultValues', function() {
+    var defaultString = "default<>\'\"abc";
+    var response = new proto.jspb.test.DefaultValues();
+
+    // Test toObject
+    var expectedObject = {
+      stringField: defaultString,
+      boolField: true,
+      intField: 11,
+      enumField: 13,
+      emptyField: '',
+      bytesField: 'bW9v'
+    };
+    assertObjectEquals(expectedObject, response.toObject());
+
+
+    // Test getters
+    response = new proto.jspb.test.DefaultValues();
+    assertEquals(defaultString, response.getStringField());
+    assertEquals(true, response.getBoolField());
+    assertEquals(11, response.getIntField());
+    assertEquals(13, response.getEnumField());
+    assertEquals('', response.getEmptyField());
+    assertEquals('bW9v', response.getBytesField());
+
+    function makeDefault(values) {
+      return new proto.jspb.test.DefaultValues(values);
+    }
+
+    // Test with undefined values,
+    // Use push to workaround IE treating undefined array elements as holes.
+    response = makeDefault([undefined, undefined, undefined, undefined]);
+    assertEquals(defaultString, response.getStringField());
+    assertEquals(true, response.getBoolField());
+    assertEquals(11, response.getIntField());
+    assertEquals(13, response.getEnumField());
+
+    // Test with null values, as would be returned by a JSON serializer.
+    response = makeDefault([null, null, null, null]);
+    assertEquals(defaultString, response.getStringField());
+    assertEquals(true, response.getBoolField());
+    assertEquals(11, response.getIntField());
+    assertEquals(13, response.getEnumField());
+
+    // Test with false-like values.
+    response = makeDefault(['', false, 0, 0]);
+    assertEquals('', response.getStringField());
+    assertEquals(false, response.getBoolField());
+    assertEquals(true, response.getIntField() == 0);
+    assertEquals(true, response.getEnumField() == 0);
+
+    // Test that clearing the values reverts them to the default state.
+    response = makeDefault(['blah', false, 111, 77]);
+    response.clearStringField(); response.clearBoolField();
+    response.clearIntField(); response.clearEnumField();
+    assertEquals(defaultString, response.getStringField());
+    assertEquals(true, response.getBoolField());
+    assertEquals(11, response.getIntField());
+    assertEquals(13, response.getEnumField());
+
+    // Test that setFoo(null) clears the values.
+    response = makeDefault(['blah', false, 111, 77]);
+    response.setStringField(null); response.setBoolField(null);
+    response.setIntField(undefined); response.setEnumField(undefined);
+    assertEquals(defaultString, response.getStringField());
+    assertEquals(true, response.getBoolField());
+    assertEquals(11, response.getIntField());
+    assertEquals(13, response.getEnumField());
+  });
+
+  it('testMessageRegistration', function() {
+    // goog.require(SomeResponse) will include its library, which will in
+    // turn add SomeResponse to the message registry.
+    assertEquals(jspb.Message.registry_['res'], proto.jspb.test.SomeResponse);
+  });
+
+  it('testClearFields', function() {
+    // We don't set 'proper' defaults, rather, bools, strings,
+    // etc, are cleared to undefined or null and take on the Javascript
+    // meaning for that value. Repeated fields are set to [] when cleared.
+    var data = ['str', true, [11], [[22], [33]], ['s1', 's2']];
+    var foo = new proto.jspb.test.OptionalFields(data);
+    foo.clearAString();
+    foo.clearABool();
+    foo.clearANestedMessage();
+    foo.clearARepeatedMessageList();
+    foo.clearARepeatedStringList();
+    assertUndefined(foo.getAString());
+    assertUndefined(foo.getABool());
+    assertUndefined(foo.getANestedMessage());
+    assertObjectEquals([], foo.getARepeatedMessageList());
+    assertObjectEquals([], foo.getARepeatedStringList());
+    // NOTE: We want the missing fields in 'expected' to be undefined,
+    // but we actually get a sparse array instead. We could use something
+    // like [1,undefined,2] to avoid this, except that this is still
+    // sparse on IE. No comment...
+    var expected = [,,, [], []];
+    expected[0] = expected[1] = expected[2] = undefined;
+    assertObjectEquals(expected, foo.toArray());
+
+    // Test set(null). We could deprecated this in favor of clear(), but
+    // it's also convenient to have.
+    data = ['str', true, [11], [[22], [33]], ['s1', 's2']];
+    foo = new proto.jspb.test.OptionalFields(data);
+    foo.setAString(null);
+    foo.setABool(null);
+    foo.setANestedMessage(null);
+    foo.setARepeatedMessageList(null);
+    foo.setARepeatedStringList(null);
+    assertNull(foo.getAString());
+    assertNull(foo.getABool());
+    assertNull(foo.getANestedMessage());
+    assertObjectEquals([], foo.getARepeatedMessageList());
+    assertObjectEquals([], foo.getARepeatedStringList());
+    assertObjectEquals([null, null, null, [], []], foo.toArray());
+
+    // Test set(undefined). Again, not something we really need, and not
+    // supported directly by our typing, but it should 'do the right thing'.
+    data = ['str', true, [11], [[22], [33]], ['s1', 's2']];
+    foo = new proto.jspb.test.OptionalFields(data);
+    foo.setAString(undefined);
+    foo.setABool(undefined);
+    foo.setANestedMessage(undefined);
+    foo.setARepeatedMessageList(undefined);
+    foo.setARepeatedStringList(undefined);
+    assertUndefined(foo.getAString());
+    assertUndefined(foo.getABool());
+    assertUndefined(foo.getANestedMessage());
+    assertObjectEquals([], foo.getARepeatedMessageList());
+    assertObjectEquals([], foo.getARepeatedStringList());
+    expected = [,,, [], []];
+    expected[0] = expected[1] = expected[2] = undefined;
+    assertObjectEquals(expected, foo.toArray());
+  });
+
+  it('testDifferenceRawObject', function() {
+    var p1 = new proto.jspb.test.HasExtensions(['hi', 'diff', {}]);
+    var p2 = new proto.jspb.test.HasExtensions(['hi', 'what',
+                                               {1000: 'unique'}]);
+    var diff = /** @type {proto.jspb.test.HasExtensions} */
+        (jspb.Message.difference(p1, p2));
+    assertUndefined(diff.getStr1());
+    assertEquals('what', diff.getStr2());
+    assertUndefined(diff.getStr3());
+    assertEquals('unique', diff.extensionObject_[1000]);
+  });
+
+  it('testEqualsSimple', function() {
+    var s1 = new proto.jspb.test.Simple1(['hi']);
+    assertTrue(jspb.Message.equals(s1, new proto.jspb.test.Simple1(['hi'])));
+    assertFalse(jspb.Message.equals(s1, new proto.jspb.test.Simple1(['bye'])));
+    var s1b = new proto.jspb.test.Simple1(['hi', ['hello']]);
+    assertTrue(jspb.Message.equals(s1b,
+        new proto.jspb.test.Simple1(['hi', ['hello']])));
+    assertTrue(jspb.Message.equals(s1b,
+        new proto.jspb.test.Simple1(['hi', ['hello', undefined,
+                                            undefined, undefined]])));
+    assertFalse(jspb.Message.equals(s1b,
+        new proto.jspb.test.Simple1(['no', ['hello']])));
+    // Test with messages of different types
+    var s2 = new proto.jspb.test.Simple2(['hi']);
+    assertFalse(jspb.Message.equals(s1, s2));
+  });
+
+  it('testEquals_softComparison', function() {
+    var s1 = new proto.jspb.test.Simple1(['hi', [], null]);
+    assertTrue(jspb.Message.equals(s1,
+        new proto.jspb.test.Simple1(['hi', []])));
+
+    var s1b = new proto.jspb.test.Simple1(['hi', [], true]);
+    assertTrue(jspb.Message.equals(s1b,
+        new proto.jspb.test.Simple1(['hi', [], 1])));
+  });
+
+  it('testEqualsComplex', function() {
+    var data1 = ['a',,, [, 11], [[, 22], [, 33]],, ['s1', 's2'],, 1];
+    var data2 = ['a',,, [, 11], [[, 22], [, 34]],, ['s1', 's2'],, 1];
+    var data3 = ['a',,, [, 11], [[, 22]],, ['s1', 's2'],, 1];
+    var data4 = ['hi'];
+    var c1a = new proto.jspb.test.Complex(data1);
+    var c1b = new proto.jspb.test.Complex(data1);
+    var c2 = new proto.jspb.test.Complex(data2);
+    var c3 = new proto.jspb.test.Complex(data3);
+    var s1 = new proto.jspb.test.Simple1(data4);
+
+    assertTrue(jspb.Message.equals(c1a, c1b));
+    assertFalse(jspb.Message.equals(c1a, c2));
+    assertFalse(jspb.Message.equals(c2, c3));
+    assertFalse(jspb.Message.equals(c1a, s1));
+  });
+
+  it('testEqualsExtensionsConstructed', function() {
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions([]),
+        new proto.jspb.test.HasExtensions([{}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'a'}]}])
+    ));
+    assertFalse(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'b'}]}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions([{100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions([{100: [{200: 'a'}]}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions([{100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions([,,, {100: [{200: 'a'}]}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions([,,, {100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions([{100: [{200: 'a'}]}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions(['hi',,, {100: [{200: 'a'}]}])
+    ));
+    assertTrue(jspb.Message.equals(
+        new proto.jspb.test.HasExtensions(['hi',,, {100: [{200: 'a'}]}]),
+        new proto.jspb.test.HasExtensions(['hi', {100: [{200: 'a'}]}])
+    ));
+  });
+
+  it('testEqualsExtensionsUnconstructed', function() {
+    assertTrue(jspb.Message.compareFields([], [{}]));
+    assertTrue(jspb.Message.compareFields([,,, {}], []));
+    assertTrue(jspb.Message.compareFields([,,, {}], [,, {}]));
+    assertTrue(jspb.Message.compareFields(
+        ['hi', {100: [{200: 'a'}]}], ['hi', {100: [{200: 'a'}]}]));
+    assertFalse(jspb.Message.compareFields(
+        ['hi', {100: [{200: 'a'}]}], ['hi', {100: [{200: 'b'}]}]));
+    assertTrue(jspb.Message.compareFields(
+        [{100: [{200: 'a'}]}], [{100: [{200: 'a'}]}]));
+    assertTrue(jspb.Message.compareFields(
+        [{100: [{200: 'a'}]}], [,,, {100: [{200: 'a'}]}]));
+    assertTrue(jspb.Message.compareFields(
+        [,,, {100: [{200: 'a'}]}], [{100: [{200: 'a'}]}]));
+    assertTrue(jspb.Message.compareFields(
+        ['hi', {100: [{200: 'a'}]}], ['hi',,, {100: [{200: 'a'}]}]));
+    assertTrue(jspb.Message.compareFields(
+        ['hi',,, {100: [{200: 'a'}]}], ['hi', {100: [{200: 'a'}]}]));
+  });
+
+  it('testToMap', function() {
+    var p1 = new proto.jspb.test.Simple1(['k', ['v']]);
+    var p2 = new proto.jspb.test.Simple1(['k1', ['v1', 'v2']]);
+    var soymap = jspb.Message.toMap([p1, p2],
+        proto.jspb.test.Simple1.prototype.getAString,
+        proto.jspb.test.Simple1.prototype.toObject);
+    assertEquals('k', soymap['k'].aString);
+    assertArrayEquals(['v'], soymap['k'].aRepeatedStringList);
+    var protomap = jspb.Message.toMap([p1, p2],
+        proto.jspb.test.Simple1.prototype.getAString);
+    assertEquals('k', protomap['k'].getAString());
+    assertArrayEquals(['v'], protomap['k'].getARepeatedStringList());
+  });
+
+  it('testClone', function() {
+    var original = new proto.jspb.test.TestClone();
+    original.setStr('v1');
+    var simple1 = new proto.jspb.test.Simple1(['x1', ['y1', 'z1']]);
+    var simple2 = new proto.jspb.test.Simple1(['x2', ['y2', 'z2']]);
+    var simple3 = new proto.jspb.test.Simple1(['x3', ['y3', 'z3']]);
+    original.setSimple1(simple1);
+    original.setSimple2List([simple2, simple3]);
+    var extension = new proto.jspb.test.CloneExtension();
+    extension.setExt('e1');
+    original.setExtension(proto.jspb.test.IsExtension.extField, extension);
+    var clone = original.cloneMessage();
+    assertArrayEquals(['v1',, ['x1', ['y1', 'z1']],,
+      [['x2', ['y2', 'z2']], ['x3', ['y3', 'z3']]],,, { 100: [, 'e1'] }],
+        clone.toArray());
+    clone.setStr('v2');
+    var simple4 = new proto.jspb.test.Simple1(['a1', ['b1', 'c1']]);
+    var simple5 = new proto.jspb.test.Simple1(['a2', ['b2', 'c2']]);
+    var simple6 = new proto.jspb.test.Simple1(['a3', ['b3', 'c3']]);
+    clone.setSimple1(simple4);
+    clone.setSimple2List([simple5, simple6]);
+    var newExtension = new proto.jspb.test.CloneExtension();
+    newExtension.setExt('e2');
+    clone.setExtension(proto.jspb.test.CloneExtension.extField, newExtension);
+    assertArrayEquals(['v2',, ['a1', ['b1', 'c1']],,
+      [['a2', ['b2', 'c2']], ['a3', ['b3', 'c3']]],,, { 100: [, 'e2'] }],
+        clone.toArray());
+    assertArrayEquals(['v1',, ['x1', ['y1', 'z1']],,
+      [['x2', ['y2', 'z2']], ['x3', ['y3', 'z3']]],,, { 100: [, 'e1'] }],
+        original.toArray());
+  });
+
+  it('testCopyInto', function() {
+    var original = new proto.jspb.test.TestClone();
+    original.setStr('v1');
+    var dest = new proto.jspb.test.TestClone();
+    dest.setStr('override');
+    var simple1 = new proto.jspb.test.Simple1(['x1', ['y1', 'z1']]);
+    var simple2 = new proto.jspb.test.Simple1(['x2', ['y2', 'z2']]);
+    var simple3 = new proto.jspb.test.Simple1(['x3', ['y3', 'z3']]);
+    var destSimple1 = new proto.jspb.test.Simple1(['ox1', ['oy1', 'oz1']]);
+    var destSimple2 = new proto.jspb.test.Simple1(['ox2', ['oy2', 'oz2']]);
+    var destSimple3 = new proto.jspb.test.Simple1(['ox3', ['oy3', 'oz3']]);
+    original.setSimple1(simple1);
+    original.setSimple2List([simple2, simple3]);
+    dest.setSimple1(destSimple1);
+    dest.setSimple2List([destSimple2, destSimple3]);
+    var extension = new proto.jspb.test.CloneExtension();
+    extension.setExt('e1');
+    original.setExtension(proto.jspb.test.CloneExtension.extField, extension);
+
+    jspb.Message.copyInto(original, dest);
+    assertArrayEquals(original.toArray(), dest.toArray());
+    assertEquals('x1', dest.getSimple1().getAString());
+    assertEquals('e1',
+        dest.getExtension(proto.jspb.test.CloneExtension.extField).getExt());
+    dest.getSimple1().setAString('new value');
+    assertNotEquals(dest.getSimple1().getAString(),
+        original.getSimple1().getAString());
+    dest.getExtension(proto.jspb.test.CloneExtension.extField).
+        setExt('new value');
+    assertNotEquals(
+        dest.getExtension(proto.jspb.test.CloneExtension.extField).getExt(),
+        original.getExtension(
+            proto.jspb.test.CloneExtension.extField).getExt());
+  });
+
+  it('testCopyInto_notSameType', function() {
+    var a = new proto.jspb.test.TestClone();
+    var b = new proto.jspb.test.Simple1(['str', ['s1', 's2']]);
+
+    var e = assertThrows(function() {
+      jspb.Message.copyInto(a, b);
+    });
+    assertContains('should have the same type', e.message);
+  });
+
+  it('testExtensions', function() {
+    var extension1 = new proto.jspb.test.IsExtension(['ext1field']);
+    var extension2 = new proto.jspb.test.Simple1(['str', ['s1', 's2']]);
+    var extendable = new proto.jspb.test.HasExtensions(['v1', 'v2', 'v3']);
+    extendable.setExtension(proto.jspb.test.IsExtension.extField, extension1);
+    extendable.setExtension(proto.jspb.test.IndirectExtension.simple,
+                            extension2);
+    extendable.setExtension(proto.jspb.test.IndirectExtension.str, 'xyzzy');
+    extendable.setExtension(proto.jspb.test.IndirectExtension.repeatedStrList,
+        ['a', 'b']);
+    var s1 = new proto.jspb.test.Simple1(['foo', ['s1', 's2']]);
+    var s2 = new proto.jspb.test.Simple1(['bar', ['t1', 't2']]);
+    extendable.setExtension(
+        proto.jspb.test.IndirectExtension.repeatedSimpleList,
+        [s1, s2]);
+    assertObjectEquals(extension1,
+        extendable.getExtension(proto.jspb.test.IsExtension.extField));
+    assertObjectEquals(extension2,
+        extendable.getExtension(proto.jspb.test.IndirectExtension.simple));
+    assertObjectEquals('xyzzy',
+        extendable.getExtension(proto.jspb.test.IndirectExtension.str));
+    assertObjectEquals(['a', 'b'], extendable.getExtension(
+        proto.jspb.test.IndirectExtension.repeatedStrList));
+    assertObjectEquals([s1, s2], extendable.getExtension(
+        proto.jspb.test.IndirectExtension.repeatedSimpleList));
+    // Not supported yet, but it should work...
+    extendable.setExtension(proto.jspb.test.IndirectExtension.simple, null);
+    assertNull(
+        extendable.getExtension(proto.jspb.test.IndirectExtension.simple));
+    extendable.setExtension(proto.jspb.test.IndirectExtension.str, null);
+    assertNull(extendable.getExtension(proto.jspb.test.IndirectExtension.str));
+
+    // These assertions will only work properly in uncompiled mode.
+    // Extension fields defined on proto2 Descriptor messages are filtered out.
+    assertUndefined(proto.jspb.test.IsExtension['simpleOption']);
+    // Extension fields with jspb.ignore = true are ignored.
+    assertUndefined(proto.jspb.test.IndirectExtension['ignored']);
+    assertUndefined(proto.jspb.test.HasExtensions['ignoredFloating']);
+  });
+
+  it('testFloatingExtensions', function() {
+    // From an autogenerated container.
+    var extendable = new proto.jspb.test.HasExtensions(['v1', 'v2', 'v3']);
+    var extension = new proto.jspb.test.Simple1(['foo', ['s1', 's2']]);
+    extendable.setExtension(proto.jspb.test.simple1, extension);
+    assertObjectEquals(extension,
+        extendable.getExtension(proto.jspb.test.simple1));
+
+    // From _lib mode.
+    extension = new proto.jspb.test.ExtensionMessage(['s1']);
+    extendable = new proto.jspb.test.TestExtensionsMessage([16]);
+    extendable.setExtension(proto.jspb.test.floatingMsgField, extension);
+    extendable.setExtension(proto.jspb.test.floatingStrField, 's2');
+    assertObjectEquals(extension,
+        extendable.getExtension(proto.jspb.test.floatingMsgField));
+    assertObjectEquals('s2',
+        extendable.getExtension(proto.jspb.test.floatingStrField));
+    assertNotUndefined(proto.jspb.exttest.floatingMsgField);
+    assertNotUndefined(proto.jspb.exttest.floatingMsgFieldTwo);
+    assertNotUndefined(proto.jspb.exttest.beta.floatingStrField);
+  });
+
+  it('testToObject_extendedObject', function() {
+    var extension1 = new proto.jspb.test.IsExtension(['ext1field']);
+    var extension2 = new proto.jspb.test.Simple1(['str', ['s1', 's2'], true]);
+    var extendable = new proto.jspb.test.HasExtensions(['v1', 'v2', 'v3']);
+    extendable.setExtension(proto.jspb.test.IsExtension.extField, extension1);
+    extendable.setExtension(proto.jspb.test.IndirectExtension.simple,
+                            extension2);
+    extendable.setExtension(proto.jspb.test.IndirectExtension.str, 'xyzzy');
+    extendable.setExtension(proto.jspb.test.IndirectExtension.repeatedStrList,
+        ['a', 'b']);
+    var s1 = new proto.jspb.test.Simple1(['foo', ['s1', 's2'], true]);
+    var s2 = new proto.jspb.test.Simple1(['bar', ['t1', 't2'], false]);
+    extendable.setExtension(
+        proto.jspb.test.IndirectExtension.repeatedSimpleList,
+        [s1, s2]);
+    assertObjectEquals({
+      str1: 'v1', str2: 'v2', str3: 'v3',
+      extField: { ext1: 'ext1field' },
+      simple: {
+        aString: 'str', aRepeatedStringList: ['s1', 's2'], aBoolean: true
+      },
+      str: 'xyzzy',
+      repeatedStrList: ['a', 'b'],
+      repeatedSimpleList: [
+        { aString: 'foo', aRepeatedStringList: ['s1', 's2'], aBoolean: true},
+        { aString: 'bar', aRepeatedStringList: ['t1', 't2'], aBoolean: false}
+      ]
+    }, extendable.toObject());
+
+    // Now, with instances included.
+    assertObjectEquals({
+      str1: 'v1', str2: 'v2', str3: 'v3',
+      extField: {
+        ext1: 'ext1field',
+        $jspbMessageInstance:
+            extendable.getExtension(proto.jspb.test.IsExtension.extField)
+      },
+      simple: {
+        aString: 'str',
+        aRepeatedStringList: ['s1', 's2'],
+        aBoolean: true,
+        $jspbMessageInstance:
+            extendable.getExtension(proto.jspb.test.IndirectExtension.simple)
+      },
+      str: 'xyzzy',
+      repeatedStrList: ['a', 'b'],
+      repeatedSimpleList: [{
+        aString: 'foo',
+        aRepeatedStringList: ['s1', 's2'],
+        aBoolean: true,
+        $jspbMessageInstance: s1
+      }, {
+        aString: 'bar',
+        aRepeatedStringList: ['t1', 't2'],
+        aBoolean: false,
+        $jspbMessageInstance: s2
+      }],
+      $jspbMessageInstance: extendable
+    }, extendable.toObject(true /* opt_includeInstance */));
+  });
+
+  it('testInitialization_emptyArray', function() {
+    var msg = new proto.jspb.test.HasExtensions([]);
+    if (jspb.Message.MINIMIZE_MEMORY_ALLOCATIONS) {
+      assertArrayEquals([], msg.toArray());
+    } else {
+      // Extension object is created past all regular fields.
+      assertArrayEquals([,,, {}], msg.toArray());
+    }
+  });
+
+  it('testInitialization_justExtensionObject', function() {
+    var msg = new proto.jspb.test.Empty([{1: 'hi'}]);
+    // The extensionObject is not moved from its original location.
+    assertArrayEquals([{1: 'hi'}], msg.toArray());
+  });
+
+  it('testInitialization_incompleteList', function() {
+    var msg = new proto.jspb.test.Empty([1, {4: 'hi'}]);
+    // The extensionObject is not moved from its original location.
+    assertArrayEquals([1, {4: 'hi'}], msg.toArray());
+  });
+
+  it('testInitialization_forwardCompatible', function() {
+    var msg = new proto.jspb.test.Empty([1, 2, 3, {1: 'hi'}]);
+    assertArrayEquals([1, 2, 3, {1: 'hi'}], msg.toArray());
+  });
+
+  it('testExtendedMessageEnsureObject', function() {
+    var data = new proto.jspb.test.HasExtensions(['str1',
+        {'a_key': 'an_object'}]);
+    assertEquals('an_object', data.extensionObject_['a_key']);
+  });
+
+  it('testToObject_hasExtensionField', function() {
+    var data = new proto.jspb.test.HasExtensions(['str1', {100: ['ext1']}]);
+    var obj = data.toObject();
+    assertEquals('str1', obj.str1);
+    assertEquals('ext1', obj.extField.ext1);
+  });
+
+  it('testGetExtension', function() {
+    var data = new proto.jspb.test.HasExtensions(['str1', {100: ['ext1']}]);
+    assertEquals('str1', data.getStr1());
+    var extension = data.getExtension(proto.jspb.test.IsExtension.extField);
+    assertNotNull(extension);
+    assertEquals('ext1', extension.getExt1());
+  });
+
+  it('testSetExtension', function() {
+    var data = new proto.jspb.test.HasExtensions();
+    var extensionMessage = new proto.jspb.test.IsExtension(['is_extension']);
+    data.setExtension(proto.jspb.test.IsExtension.extField, extensionMessage);
+    var obj = data.toObject();
+    assertNotNull(
+        data.getExtension(proto.jspb.test.IsExtension.extField));
+    assertEquals('is_extension', obj.extField.ext1);
+  });
+
+  /**
+   * Note that group is long deprecated, we only support it because JsPb has
+   * a goal of being able to generate JS classes for all proto descriptors.
+   */
+  it('testGroups', function() {
+    var group = new proto.jspb.test.TestGroup();
+    var someGroup = new proto.jspb.test.TestGroup.RepeatedGroup();
+    someGroup.setId('g1');
+    someGroup.setSomeBoolList([true, false]);
+    group.setRepeatedGroupList([someGroup]);
+    var groups = group.getRepeatedGroupList();
+    assertEquals('g1', groups[0].getId());
+    assertObjectEquals([true, false], groups[0].getSomeBoolList());
+    assertObjectEquals({id: 'g1', someBoolList: [true, false]},
+        groups[0].toObject());
+    assertObjectEquals({
+      repeatedGroupList: [{id: 'g1', someBoolList: [true, false]}],
+      requiredGroup: {id: undefined},
+      optionalGroup: undefined,
+      requiredSimple: {aRepeatedStringList: [], aString: undefined},
+      optionalSimple: undefined,
+      id: undefined
+    }, group.toObject());
+    var group1 = new proto.jspb.test.TestGroup1();
+    group1.setGroup(someGroup);
+    assertEquals(someGroup, group1.getGroup());
+  });
+
+  it('testNonExtensionFieldsAfterExtensionRange', function() {
+    var data = [{'1': 'a_string'}];
+    var message = new proto.jspb.test.Complex(data);
+    assertArrayEquals([], message.getARepeatedStringList());
+  });
+
+  it('testReservedGetterNames', function() {
+    var message = new proto.jspb.test.TestReservedNames();
+    message.setExtension$(11);
+    message.setExtension(proto.jspb.test.TestReservedNamesExtension.foo, 12);
+    assertEquals(11, message.getExtension$());
+    assertEquals(12, message.getExtension(
+        proto.jspb.test.TestReservedNamesExtension.foo));
+    assertObjectEquals({extension: 11, foo: 12}, message.toObject());
+  });
+
+  it('testInitializeMessageWithUnsetOneof', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof([]);
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.
+            PARTIAL_ONEOF_NOT_SET,
+        message.getPartialOneofCase());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.RecursiveOneofCase.
+            RECURSIVE_ONEOF_NOT_SET,
+        message.getRecursiveOneofCase());
+  });
+
+  it('testInitializeMessageWithSingleValueSetInOneof', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof([,, 'x']);
+
+    assertEquals('x', message.getPone());
+    assertUndefined(message.getPthree());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.PONE,
+        message.getPartialOneofCase());
+  });
+
+  it('testKeepsLastWireValueSetInUnion_multipleValues', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof([,, 'x',, 'y']);
+
+    assertUndefined('x', message.getPone());
+    assertEquals('y', message.getPthree());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.PTHREE,
+        message.getPartialOneofCase());
+  });
+
+  it('testSettingOneofFieldClearsOthers', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertUndefined(message.getPone());
+    assertUndefined(message.getPthree());
+
+    message.setPone('hi');
+    assertEquals('hi', message.getPone());
+    assertUndefined(message.getPthree());
+
+    message.setPthree('bye');
+    assertUndefined(message.getPone());
+    assertEquals('bye', message.getPthree());
+  });
+
+  it('testSettingOneofFieldDoesNotClearFieldsFromOtherUnions', function() {
+    var other = new proto.jspb.test.TestMessageWithOneof;
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertUndefined(message.getPone());
+    assertUndefined(message.getPthree());
+    assertUndefined(message.getRone());
+
+    message.setPone('hi');
+    message.setRone(other);
+    assertEquals('hi', message.getPone());
+    assertUndefined(message.getPthree());
+    assertEquals(other, message.getRone());
+
+    message.setPthree('bye');
+    assertUndefined(message.getPone());
+    assertEquals('bye', message.getPthree());
+    assertEquals(other, message.getRone());
+  });
+
+  it('testUnsetsOneofCaseWhenFieldIsCleared', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.
+            PARTIAL_ONEOF_NOT_SET,
+        message.getPartialOneofCase());
+
+    message.setPone('hi');
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.PONE,
+        message.getPartialOneofCase());
+
+    message.clearPone();
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.
+            PARTIAL_ONEOF_NOT_SET,
+        message.getPartialOneofCase());
+  });
+
+  it('testMessageWithDefaultOneofValues', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertEquals(1234, message.getAone());
+    assertUndefined(message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase
+            .DEFAULT_ONEOF_A_NOT_SET,
+        message.getDefaultOneofACase());
+
+    message.setAone(567);
+    assertEquals(567, message.getAone());
+    assertUndefined(message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase.AONE,
+        message.getDefaultOneofACase());
+
+    message.setAtwo(890);
+    assertEquals(1234, message.getAone());
+    assertEquals(890, message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase.ATWO,
+        message.getDefaultOneofACase());
+
+    message.clearAtwo();
+    assertEquals(1234, message.getAone());
+    assertUndefined(message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase
+            .DEFAULT_ONEOF_A_NOT_SET,
+        message.getDefaultOneofACase());
+  });
+
+  it('testMessageWithDefaultOneofValues_defaultNotOnFirstField', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertUndefined(message.getBone());
+    assertEquals(1234, message.getBtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase
+            .DEFAULT_ONEOF_B_NOT_SET,
+        message.getDefaultOneofBCase());
+
+    message.setBone(2);
+    assertEquals(2, message.getBone());
+    assertEquals(1234, message.getBtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase.BONE,
+        message.getDefaultOneofBCase());
+
+    message.setBtwo(3);
+    assertUndefined(message.getBone());
+    assertEquals(3, message.getBtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase.BTWO,
+        message.getDefaultOneofBCase());
+
+    message.clearBtwo();
+    assertUndefined(message.getBone());
+    assertEquals(1234, message.getBtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase
+            .DEFAULT_ONEOF_B_NOT_SET,
+        message.getDefaultOneofBCase());
+  });
+
+  it('testInitializeMessageWithOneofDefaults', function() {
+    var message =
+        new proto.jspb.test.TestMessageWithOneof(new Array(9).concat(567));
+    assertEquals(567, message.getAone());
+    assertUndefined(message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase.AONE,
+        message.getDefaultOneofACase());
+
+    message =
+        new proto.jspb.test.TestMessageWithOneof(new Array(10).concat(890));
+    assertEquals(1234, message.getAone());
+    assertEquals(890, message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase.ATWO,
+        message.getDefaultOneofACase());
+
+    message =
+        new proto.jspb.test.TestMessageWithOneof(new Array(9).concat(567,890));
+    assertEquals(1234, message.getAone());
+    assertEquals(890, message.getAtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.DefaultOneofACase.ATWO,
+        message.getDefaultOneofACase());
+  });
+
+  it('testInitializeMessageWithOneofDefaults_defaultNotSetOnFirstField',
+      function() {
+        var message;
+
+        message =
+            new proto.jspb.test.TestMessageWithOneof(new Array(11).concat(567));
+        assertEquals(567, message.getBone());
+        assertEquals(1234, message.getBtwo());
+        assertEquals(
+            proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase.BONE,
+            message.getDefaultOneofBCase());
+
+        message =
+            new proto.jspb.test.TestMessageWithOneof(new Array(12).concat(890));
+        assertUndefined(message.getBone());
+        assertEquals(890, message.getBtwo());
+        assertEquals(
+            proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase.BTWO,
+            message.getDefaultOneofBCase());
+
+        message = new proto.jspb.test.TestMessageWithOneof(
+            new Array(11).concat(567,890));
+        assertUndefined(message.getBone());
+        assertEquals(890, message.getBtwo());
+        assertEquals(
+            proto.jspb.test.TestMessageWithOneof.DefaultOneofBCase.BTWO,
+            message.getDefaultOneofBCase());
+      });
+
+  it('testOneofContainingAnotherMessage', function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.RecursiveOneofCase.
+            RECURSIVE_ONEOF_NOT_SET,
+        message.getRecursiveOneofCase());
+
+    var other = new proto.jspb.test.TestMessageWithOneof;
+    message.setRone(other);
+    assertEquals(other, message.getRone());
+    assertUndefined(message.getRtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.RecursiveOneofCase.RONE,
+        message.getRecursiveOneofCase());
+
+    message.setRtwo('hi');
+    assertUndefined(message.getRone());
+    assertEquals('hi', message.getRtwo());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.RecursiveOneofCase.RTWO,
+        message.getRecursiveOneofCase());
+  });
+
+  it('testQueryingOneofCaseEnsuresOnlyOneFieldIsSetInUnderlyingArray',
+     function() {
+    var message = new proto.jspb.test.TestMessageWithOneof;
+    message.setPone('x');
+    assertEquals('x', message.getPone());
+    assertUndefined(message.getPthree());
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.PONE,
+        message.getPartialOneofCase());
+
+    var array = message.toArray();
+    assertEquals('x', array[2]);
+    assertUndefined(array[4]);
+    array[4] = 'y';
+
+    assertEquals(
+        proto.jspb.test.TestMessageWithOneof.PartialOneofCase.PTHREE,
+        message.getPartialOneofCase());
+    assertUndefined(array[2]);
+    assertEquals('y', array[4]);
+  });
+
+});
diff --git a/js/proto3_test.js b/js/proto3_test.js
new file mode 100644
index 00000000..8102bab6
--- /dev/null
+++ b/js/proto3_test.js
@@ -0,0 +1,279 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+goog.require('goog.testing.asserts');
+goog.require('proto.jspb.test.ForeignMessage');
+goog.require('proto.jspb.test.Proto3Enum');
+goog.require('proto.jspb.test.TestProto3');
+
+/**
+ * Helper: compare a bytes field to a string with codepoints 0--255.
+ * @param {Uint8Array|string} arr
+ * @param {string} str
+ * @return {boolean}
+ */
+function bytesCompare(arr, str) {
+  if (arr.length != str.length) {
+    return false;
+  }
+  if (typeof arr == 'string') {
+    for (var i = 0; i < arr.length; i++) {
+      if (arr.charCodeAt(i) != str.charCodeAt(i)) {
+        return false;
+      }
+    }
+    return true;
+  } else {
+    for (var i = 0; i < arr.length; i++) {
+      if (arr[i] != str.charCodeAt(i)) {
+        return false;
+      }
+    }
+    return true;
+  }
+}
+
+
+describe('proto3Test', function() {
+  /**
+   * Test defaults for proto3 message fields.
+   */
+  it('testProto3FieldDefaults', function() {
+    var msg = new proto.jspb.test.TestProto3();
+
+    assertEquals(msg.getOptionalInt32(), 0);
+    assertEquals(msg.getOptionalInt64(), 0);
+    assertEquals(msg.getOptionalUint32(), 0);
+    assertEquals(msg.getOptionalUint64(), 0);
+    assertEquals(msg.getOptionalSint32(), 0);
+    assertEquals(msg.getOptionalSint64(), 0);
+    assertEquals(msg.getOptionalFixed32(), 0);
+    assertEquals(msg.getOptionalFixed64(), 0);
+    assertEquals(msg.getOptionalSfixed32(), 0);
+    assertEquals(msg.getOptionalSfixed64(), 0);
+    assertEquals(msg.getOptionalFloat(), 0);
+    assertEquals(msg.getOptionalDouble(), 0);
+    assertEquals(msg.getOptionalString(), '');
+
+    // If/when we change bytes fields to return Uint8Array, we'll want to switch
+    // to this assertion instead:
+    //assertEquals(msg.getOptionalBytes() instanceof Uint8Array, true);
+    assertEquals(typeof msg.getOptionalBytes(), 'string');
+
+    assertEquals(msg.getOptionalBytes().length, 0);
+    assertEquals(msg.getOptionalForeignEnum(), proto.jspb.test.Proto3Enum.PROTO3_FOO);
+    assertEquals(msg.getOptionalForeignMessage(), undefined);
+    assertEquals(msg.getOptionalForeignMessage(), undefined);
+
+    assertEquals(msg.getRepeatedInt32List().length, 0);
+    assertEquals(msg.getRepeatedInt64List().length, 0);
+    assertEquals(msg.getRepeatedUint32List().length, 0);
+    assertEquals(msg.getRepeatedUint64List().length, 0);
+    assertEquals(msg.getRepeatedSint32List().length, 0);
+    assertEquals(msg.getRepeatedSint64List().length, 0);
+    assertEquals(msg.getRepeatedFixed32List().length, 0);
+    assertEquals(msg.getRepeatedFixed64List().length, 0);
+    assertEquals(msg.getRepeatedSfixed32List().length, 0);
+    assertEquals(msg.getRepeatedSfixed64List().length, 0);
+    assertEquals(msg.getRepeatedFloatList().length, 0);
+    assertEquals(msg.getRepeatedDoubleList().length, 0);
+    assertEquals(msg.getRepeatedStringList().length, 0);
+    assertEquals(msg.getRepeatedBytesList().length, 0);
+    assertEquals(msg.getRepeatedForeignEnumList().length, 0);
+    assertEquals(msg.getRepeatedForeignMessageList().length, 0);
+
+  });
+
+
+  /**
+   * Test that all fields can be set and read via a serialization roundtrip.
+   */
+  it('testProto3FieldSetGet', function() {
+    var msg = new proto.jspb.test.TestProto3();
+
+    msg.setOptionalInt32(-42);
+    msg.setOptionalInt64(-0x7fffffff00000000);
+    msg.setOptionalUint32(0x80000000);
+    msg.setOptionalUint64(0xf000000000000000);
+    msg.setOptionalSint32(-100);
+    msg.setOptionalSint64(-0x8000000000000000);
+    msg.setOptionalFixed32(1234);
+    msg.setOptionalFixed64(0x1234567800000000);
+    msg.setOptionalSfixed32(-1234);
+    msg.setOptionalSfixed64(-0x1234567800000000);
+    msg.setOptionalFloat(1.5);
+    msg.setOptionalDouble(-1.5);
+    msg.setOptionalBool(true);
+    msg.setOptionalString('hello world');
+    msg.setOptionalBytes('bytes');
+    var submsg = new proto.jspb.test.ForeignMessage();
+    submsg.setC(16);
+    msg.setOptionalForeignMessage(submsg);
+    msg.setOptionalForeignEnum(proto.jspb.test.Proto3Enum.PROTO3_BAR);
+
+    msg.setRepeatedInt32List([-42]);
+    msg.setRepeatedInt64List([-0x7fffffff00000000]);
+    msg.setRepeatedUint32List([0x80000000]);
+    msg.setRepeatedUint64List([0xf000000000000000]);
+    msg.setRepeatedSint32List([-100]);
+    msg.setRepeatedSint64List([-0x8000000000000000]);
+    msg.setRepeatedFixed32List([1234]);
+    msg.setRepeatedFixed64List([0x1234567800000000]);
+    msg.setRepeatedSfixed32List([-1234]);
+    msg.setRepeatedSfixed64List([-0x1234567800000000]);
+    msg.setRepeatedFloatList([1.5]);
+    msg.setRepeatedDoubleList([-1.5]);
+    msg.setRepeatedBoolList([true]);
+    msg.setRepeatedStringList(['hello world']);
+    msg.setRepeatedBytesList(['bytes']);
+    submsg = new proto.jspb.test.ForeignMessage();
+    submsg.setC(1000);
+    msg.setRepeatedForeignMessageList([submsg]);
+    msg.setRepeatedForeignEnumList([proto.jspb.test.Proto3Enum.PROTO3_BAR]);
+
+    msg.setOneofString('asdf');
+
+    var serialized = msg.serializeBinary();
+    msg = proto.jspb.test.TestProto3.deserializeBinary(serialized);
+
+    assertEquals(msg.getOptionalInt32(), -42);
+    assertEquals(msg.getOptionalInt64(), -0x7fffffff00000000);
+    assertEquals(msg.getOptionalUint32(), 0x80000000);
+    assertEquals(msg.getOptionalUint64(), 0xf000000000000000);
+    assertEquals(msg.getOptionalSint32(), -100);
+    assertEquals(msg.getOptionalSint64(), -0x8000000000000000);
+    assertEquals(msg.getOptionalFixed32(), 1234);
+    assertEquals(msg.getOptionalFixed64(), 0x1234567800000000);
+    assertEquals(msg.getOptionalSfixed32(), -1234);
+    assertEquals(msg.getOptionalSfixed64(), -0x1234567800000000);
+    assertEquals(msg.getOptionalFloat(), 1.5);
+    assertEquals(msg.getOptionalDouble(), -1.5);
+    assertEquals(msg.getOptionalBool(), true);
+    assertEquals(msg.getOptionalString(), 'hello world');
+    assertEquals(true, bytesCompare(msg.getOptionalBytes(), 'bytes'));
+    assertEquals(msg.getOptionalForeignMessage().getC(), 16);
+    assertEquals(msg.getOptionalForeignEnum(),
+        proto.jspb.test.Proto3Enum.PROTO3_BAR);
+
+    assertElementsEquals(msg.getRepeatedInt32List(), [-42]);
+    assertElementsEquals(msg.getRepeatedInt64List(), [-0x7fffffff00000000]);
+    assertElementsEquals(msg.getRepeatedUint32List(), [0x80000000]);
+    assertElementsEquals(msg.getRepeatedUint64List(), [0xf000000000000000]);
+    assertElementsEquals(msg.getRepeatedSint32List(), [-100]);
+    assertElementsEquals(msg.getRepeatedSint64List(), [-0x8000000000000000]);
+    assertElementsEquals(msg.getRepeatedFixed32List(), [1234]);
+    assertElementsEquals(msg.getRepeatedFixed64List(), [0x1234567800000000]);
+    assertElementsEquals(msg.getRepeatedSfixed32List(), [-1234]);
+    assertElementsEquals(msg.getRepeatedSfixed64List(), [-0x1234567800000000]);
+    assertElementsEquals(msg.getRepeatedFloatList(), [1.5]);
+    assertElementsEquals(msg.getRepeatedDoubleList(), [-1.5]);
+    assertElementsEquals(msg.getRepeatedBoolList(), [true]);
+    assertElementsEquals(msg.getRepeatedStringList(), ['hello world']);
+    assertEquals(msg.getRepeatedBytesList().length, 1);
+    assertEquals(true, bytesCompare(msg.getRepeatedBytesList()[0], 'bytes'));
+    assertEquals(msg.getRepeatedForeignMessageList().length, 1);
+    assertEquals(msg.getRepeatedForeignMessageList()[0].getC(), 1000);
+    assertElementsEquals(msg.getRepeatedForeignEnumList(),
+        [proto.jspb.test.Proto3Enum.PROTO3_BAR]);
+
+    assertEquals(msg.getOneofString(), 'asdf');
+  });
+
+
+  /**
+   * Test that oneofs continue to have a notion of field presence.
+   */
+  it('testOneofs', function() {
+    var msg = new proto.jspb.test.TestProto3();
+
+    assertEquals(msg.getOneofUint32(), undefined);
+    assertEquals(msg.getOneofForeignMessage(), undefined);
+    assertEquals(msg.getOneofString(), undefined);
+    assertEquals(msg.getOneofBytes(), undefined);
+
+    msg.setOneofUint32(42);
+    assertEquals(msg.getOneofUint32(), 42);
+    assertEquals(msg.getOneofForeignMessage(), undefined);
+    assertEquals(msg.getOneofString(), undefined);
+    assertEquals(msg.getOneofBytes(), undefined);
+
+
+    var submsg = new proto.jspb.test.ForeignMessage();
+    msg.setOneofForeignMessage(submsg);
+    assertEquals(msg.getOneofUint32(), undefined);
+    assertEquals(msg.getOneofForeignMessage(), submsg);
+    assertEquals(msg.getOneofString(), undefined);
+    assertEquals(msg.getOneofBytes(), undefined);
+
+    msg.setOneofString('hello');
+    assertEquals(msg.getOneofUint32(), undefined);
+    assertEquals(msg.getOneofForeignMessage(), undefined);
+    assertEquals(msg.getOneofString(), 'hello');
+    assertEquals(msg.getOneofBytes(), undefined);
+
+    msg.setOneofBytes('\u00FF\u00FF');
+    assertEquals(msg.getOneofUint32(), undefined);
+    assertEquals(msg.getOneofForeignMessage(), undefined);
+    assertEquals(msg.getOneofString(), undefined);
+    assertEquals(msg.getOneofBytes(), '\u00FF\u00FF');
+  });
+
+
+  /**
+   * Test that "default"-valued primitive fields are not emitted on the wire.
+   */
+  it('testNoSerializeDefaults', function() {
+    var msg = new proto.jspb.test.TestProto3();
+
+    // Set each primitive to a non-default value, then back to its default, to
+    // ensure that the serialization is actually checking the value and not just
+    // whether it has ever been set.
+    msg.setOptionalInt32(42);
+    msg.setOptionalInt32(0);
+    msg.setOptionalDouble(3.14);
+    msg.setOptionalDouble(0.0);
+    msg.setOptionalBool(true);
+    msg.setOptionalBool(false);
+    msg.setOptionalString('hello world');
+    msg.setOptionalString('');
+    msg.setOptionalBytes('\u00FF\u00FF');
+    msg.setOptionalBytes('');
+    msg.setOptionalForeignMessage(new proto.jspb.test.ForeignMessage());
+    msg.setOptionalForeignMessage(null);
+    msg.setOptionalForeignEnum(proto.jspb.test.Proto3Enum.PROTO3_BAR);
+    msg.setOptionalForeignEnum(proto.jspb.test.Proto3Enum.PROTO3_FOO);
+    msg.setOneofUint32(32);
+    msg.setOneofUint32(null);
+
+
+    var serialized = msg.serializeBinary();
+    assertEquals(0, serialized.length);
+  });
+});
diff --git a/js/proto3_test.proto b/js/proto3_test.proto
new file mode 100644
index 00000000..acb67164
--- /dev/null
+++ b/js/proto3_test.proto
@@ -0,0 +1,89 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto3";
+
+import "testbinary.proto";
+
+package jspb.test;
+
+message TestProto3 {
+     int32 optional_int32    =  1;
+     int64 optional_int64    =  2;
+    uint32 optional_uint32   =  3;
+    uint64 optional_uint64   =  4;
+    sint32 optional_sint32   =  5;
+    sint64 optional_sint64   =  6;
+   fixed32 optional_fixed32  =  7;
+   fixed64 optional_fixed64  =  8;
+  sfixed32 optional_sfixed32 =  9;
+  sfixed64 optional_sfixed64 = 10;
+     float optional_float    = 11;
+    double optional_double   = 12;
+      bool optional_bool     = 13;
+    string optional_string   = 14;
+     bytes optional_bytes    = 15;
+
+  ForeignMessage optional_foreign_message = 19;
+  Proto3Enum     optional_foreign_enum    = 22;
+
+  repeated    int32 repeated_int32    = 31;
+  repeated    int64 repeated_int64    = 32;
+  repeated   uint32 repeated_uint32   = 33;
+  repeated   uint64 repeated_uint64   = 34;
+  repeated   sint32 repeated_sint32   = 35;
+  repeated   sint64 repeated_sint64   = 36;
+  repeated  fixed32 repeated_fixed32  = 37;
+  repeated  fixed64 repeated_fixed64  = 38;
+  repeated sfixed32 repeated_sfixed32 = 39;
+  repeated sfixed64 repeated_sfixed64 = 40;
+  repeated    float repeated_float    = 41;
+  repeated   double repeated_double   = 42;
+  repeated     bool repeated_bool     = 43;
+  repeated   string repeated_string   = 44;
+  repeated    bytes repeated_bytes    = 45;
+
+  repeated ForeignMessage repeated_foreign_message = 49;
+  repeated Proto3Enum     repeated_foreign_enum    = 52;
+
+
+  oneof oneof_field {
+    uint32 oneof_uint32 = 111;
+    ForeignMessage oneof_foreign_message = 112;
+    string oneof_string = 113;
+    bytes oneof_bytes = 114;
+  }
+}
+
+enum Proto3Enum {
+  PROTO3_FOO = 0;
+  PROTO3_BAR = 1;
+  PROTO3_BAZ = 2;
+}
diff --git a/js/test.proto b/js/test.proto
new file mode 100644
index 00000000..5f9078ef
--- /dev/null
+++ b/js/test.proto
@@ -0,0 +1,212 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: mwr@google.com (Mark Rawling)
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+import "google/protobuf/descriptor.proto";
+
+package jspb.test;
+
+message Empty {
+}
+
+enum OuterEnum {
+  FOO = 1;
+  BAR = 2;
+}
+
+message EnumContainer {
+  optional OuterEnum outer_enum = 1;
+}
+
+message Simple1 {
+  required string a_string = 1;
+  repeated string a_repeated_string = 2;
+  optional bool a_boolean = 3;
+}
+
+// A message that differs from Simple1 only by name
+message Simple2 {
+  required string a_string = 1;
+  repeated string a_repeated_string = 2;
+}
+
+message SpecialCases {
+  required string normal = 1;
+  // Examples of Js reserved names that are converted to pb_<name>.
+  required string default = 2;
+  required string function = 3;
+  required string var = 4;
+}
+
+message OptionalFields {
+  message Nested {
+    optional int32 an_int = 1;
+  }
+  optional string a_string = 1;
+  required bool a_bool = 2;
+  optional Nested a_nested_message = 3;
+  repeated Nested a_repeated_message = 4;
+  repeated string a_repeated_string = 5;
+}
+
+message HasExtensions {
+  optional string str1 = 1;
+  optional string str2 = 2;
+  optional string str3 = 3;
+  extensions 10 to max;
+}
+
+message Complex {
+  message Nested {
+    required int32 an_int = 2;
+  }
+  required string a_string = 1;
+  required bool an_out_of_order_bool = 9;
+  optional Nested a_nested_message = 4;
+  repeated Nested a_repeated_message = 5;
+  repeated string a_repeated_string = 7;
+}
+
+message IsExtension {
+  extend HasExtensions {
+    optional IsExtension ext_field = 100;
+  }
+  optional string ext1 = 1;
+
+  // Extensions of proto2 Descriptor messages will be ignored.
+  extend google.protobuf.EnumOptions {
+    optional string simple_option = 42113038;
+  }
+}
+
+message IndirectExtension {
+  extend HasExtensions {
+    optional Simple1 simple = 101;
+    optional string str = 102;
+    repeated string repeated_str = 103;
+    repeated Simple1 repeated_simple = 104;
+  }
+}
+
+extend HasExtensions {
+  optional Simple1 simple1 = 105;
+}
+
+message DefaultValues {
+  enum Enum {
+    E1 = 13;
+    E2 = 77;
+  }
+  optional string string_field = 1 [default="default<>\'\"abc"];
+  optional bool bool_field = 2 [default=true];
+  optional int64 int_field = 3 [default=11];
+  optional Enum enum_field = 4 [default=E1];
+  optional string empty_field = 6 [default=""];
+  optional bytes bytes_field = 8 [default="moo"]; // Base64 encoding is "bW9v"
+}
+
+message TestClone {
+  optional string str = 1;
+  optional Simple1 simple1 = 3;
+  repeated Simple1 simple2 = 5;
+  optional string unused = 7;
+  extensions 10 to max;
+}
+
+message CloneExtension {
+  extend TestClone {
+    optional CloneExtension ext_field = 100;
+  }
+  optional string ext = 2;
+}
+
+message TestGroup {
+  repeated group RepeatedGroup = 1 {
+    required string id = 1;
+    repeated bool some_bool = 2;
+  }
+  required group RequiredGroup = 2 {
+    required string id = 1;
+  }
+  optional group OptionalGroup = 3 {
+    required string id = 1;
+  }
+  optional string id = 4;
+  required Simple2 required_simple = 5;
+  optional Simple2 optional_simple = 6;
+}
+
+message TestGroup1 {
+  optional TestGroup.RepeatedGroup group = 1;
+}
+
+message TestReservedNames {
+  optional int32 extension = 1;
+  extensions 10 to max;
+}
+
+message TestReservedNamesExtension {
+  extend TestReservedNames {
+    optional int32 foo = 10;
+  }
+}
+
+message TestMessageWithOneof {
+
+  oneof partial_oneof {
+    string pone = 3;
+    string pthree = 5;
+  }
+
+  oneof recursive_oneof {
+    TestMessageWithOneof rone = 6;
+    string rtwo = 7;
+  }
+
+  optional bool normal_field = 8;
+  repeated string repeated_field = 9;
+
+  oneof default_oneof_a {
+    int32 aone = 10 [default = 1234];
+    int32 atwo = 11;
+  }
+
+  oneof default_oneof_b {
+    int32 bone = 12;
+    int32 btwo = 13 [default = 1234];
+  }
+}
+
diff --git a/js/test2.proto b/js/test2.proto
new file mode 100644
index 00000000..44e55eff
--- /dev/null
+++ b/js/test2.proto
@@ -0,0 +1,54 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+package jspb.test;
+
+message TestExtensionsMessage {
+  optional int32 intfield = 1;
+  extensions 100 to max;
+}
+
+message ExtensionMessage {
+  extend TestExtensionsMessage {
+    optional ExtensionMessage ext_field = 100;
+  }
+  optional string ext1 = 1;
+}
+
+// Floating extensions are only supported when generating a _lib.js library.
+extend TestExtensionsMessage {
+  optional ExtensionMessage floating_msg_field = 101;
+  optional string floating_str_field = 102;
+}
diff --git a/js/test3.proto b/js/test3.proto
new file mode 100644
index 00000000..940a552e
--- /dev/null
+++ b/js/test3.proto
@@ -0,0 +1,53 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+package jspb.exttest;
+
+message TestExtensionsMessage {
+  optional int32 intfield = 1;
+  extensions 100 to max;
+}
+
+message ExtensionMessage {
+  extend TestExtensionsMessage {
+    optional ExtensionMessage ext_field = 100;
+  }
+  optional string ext1 = 1;
+}
+
+extend TestExtensionsMessage {
+  optional ExtensionMessage floating_msg_field = 101;
+  optional string floating_str_field = 102;
+}
diff --git a/js/test4.proto b/js/test4.proto
new file mode 100644
index 00000000..cf2451e9
--- /dev/null
+++ b/js/test4.proto
@@ -0,0 +1,42 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+package jspb.exttest;
+
+import "test3.proto";
+
+extend TestExtensionsMessage {
+  optional ExtensionMessage floating_msg_field_two = 103;
+}
diff --git a/js/test5.proto b/js/test5.proto
new file mode 100644
index 00000000..34979517
--- /dev/null
+++ b/js/test5.proto
@@ -0,0 +1,44 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+option java_package = "com.google.apps.jspb.proto";
+option java_multiple_files = true;
+
+package jspb.exttest.beta;
+
+message TestBetaExtensionsMessage {
+  extensions 100 to max;
+}
+
+extend TestBetaExtensionsMessage {
+  optional string floating_str_field = 101;
+}
diff --git a/js/test_bootstrap.js b/js/test_bootstrap.js
new file mode 100644
index 00000000..9d00a1c4
--- /dev/null
+++ b/js/test_bootstrap.js
@@ -0,0 +1,41 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/**
+ * @fileoverview Sets flags for uncompiled JSUnit tests.
+ */
+
+/**
+ * Set uncompiled flags.
+ */
+var CLOSURE_DEFINES = {
+    // Enable the fromObject method on the message class.
+    'jspb.Message.GENERATE_FROM_OBJECT': true
+};
diff --git a/js/testbinary.proto b/js/testbinary.proto
new file mode 100644
index 00000000..60c70190
--- /dev/null
+++ b/js/testbinary.proto
@@ -0,0 +1,185 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// LINT: ALLOW_GROUPS
+
+syntax = "proto2";
+
+
+package jspb.test;
+
+// These types are borrowed from `unittest.proto` in the protobuf tree. We want
+// to ensure that the binary-format support will handle all field types
+// properly.
+message TestAllTypes {
+  optional    int32 optional_int32    =  1;
+  optional    int64 optional_int64    =  2;
+  optional   uint32 optional_uint32   =  3;
+  optional   uint64 optional_uint64   =  4;
+  optional   sint32 optional_sint32   =  5;
+  optional   sint64 optional_sint64   =  6;
+  optional  fixed32 optional_fixed32  =  7;
+  optional  fixed64 optional_fixed64  =  8;
+  optional sfixed32 optional_sfixed32 =  9;
+  optional sfixed64 optional_sfixed64 = 10;
+  optional    float optional_float    = 11;
+  optional   double optional_double   = 12;
+  optional     bool optional_bool     = 13;
+  optional   string optional_string   = 14;
+  optional    bytes optional_bytes    = 15;
+  optional group OptionalGroup = 16 {
+    optional int32 a = 17;
+  }
+
+  optional ForeignMessage                       optional_foreign_message = 19;
+  optional ForeignEnum                          optional_foreign_enum    = 22;
+
+  // Repeated
+  repeated    int32 repeated_int32    = 31;
+  repeated    int64 repeated_int64    = 32;
+  repeated   uint32 repeated_uint32   = 33;
+  repeated   uint64 repeated_uint64   = 34;
+  repeated   sint32 repeated_sint32   = 35;
+  repeated   sint64 repeated_sint64   = 36;
+  repeated  fixed32 repeated_fixed32  = 37;
+  repeated  fixed64 repeated_fixed64  = 38;
+  repeated sfixed32 repeated_sfixed32 = 39;
+  repeated sfixed64 repeated_sfixed64 = 40;
+  repeated    float repeated_float    = 41;
+  repeated   double repeated_double   = 42;
+  repeated     bool repeated_bool     = 43;
+  repeated   string repeated_string   = 44;
+  repeated    bytes repeated_bytes    = 45;
+
+  repeated group RepeatedGroup = 46 {
+    optional int32 a = 47;
+  }
+
+  repeated ForeignMessage                       repeated_foreign_message = 49;
+  repeated ForeignEnum                          repeated_foreign_enum    = 52;
+
+  // Packed repeated
+  repeated    int32 packed_repeated_int32    = 61 [packed=true];
+  repeated    int64 packed_repeated_int64    = 62 [packed=true];
+  repeated   uint32 packed_repeated_uint32   = 63 [packed=true];
+  repeated   uint64 packed_repeated_uint64   = 64 [packed=true];
+  repeated   sint32 packed_repeated_sint32   = 65 [packed=true];
+  repeated   sint64 packed_repeated_sint64   = 66 [packed=true];
+  repeated  fixed32 packed_repeated_fixed32  = 67 [packed=true];
+  repeated  fixed64 packed_repeated_fixed64  = 68 [packed=true];
+  repeated sfixed32 packed_repeated_sfixed32 = 69 [packed=true];
+  repeated sfixed64 packed_repeated_sfixed64 = 70 [packed=true];
+  repeated    float packed_repeated_float    = 71 [packed=true];
+  repeated   double packed_repeated_double   = 72 [packed=true];
+  repeated     bool packed_repeated_bool     = 73 [packed=true];
+
+  oneof oneof_field {
+    uint32 oneof_uint32 = 111;
+    ForeignMessage oneof_foreign_message = 112;
+    string oneof_string = 113;
+    bytes oneof_bytes = 114;
+  }
+
+}
+
+message ForeignMessage {
+  optional int32 c = 1;
+}
+
+enum ForeignEnum {
+  FOREIGN_FOO = 4;
+  FOREIGN_BAR = 5;
+  FOREIGN_BAZ = 6;
+}
+
+message TestExtendable {
+  extensions 1 to max;
+}
+
+message ExtendsWithMessage {
+  extend TestExtendable {
+    optional ExtendsWithMessage optional_extension = 19;
+    repeated ExtendsWithMessage repeated_extension = 49;
+  }
+  optional int32 foo = 1;
+}
+
+extend TestExtendable {
+  optional    int32 extend_optional_int32    =  1;
+  optional    int64 extend_optional_int64    =  2;
+  optional   uint32 extend_optional_uint32   =  3;
+  optional   uint64 extend_optional_uint64   =  4;
+  optional   sint32 extend_optional_sint32   =  5;
+  optional   sint64 extend_optional_sint64   =  6;
+  optional  fixed32 extend_optional_fixed32  =  7;
+  optional  fixed64 extend_optional_fixed64  =  8;
+  optional sfixed32 extend_optional_sfixed32 =  9;
+  optional sfixed64 extend_optional_sfixed64 = 10;
+  optional    float extend_optional_float    = 11;
+  optional   double extend_optional_double   = 12;
+  optional     bool extend_optional_bool     = 13;
+  optional   string extend_optional_string   = 14;
+  optional    bytes extend_optional_bytes    = 15;
+  optional ForeignEnum extend_optional_foreign_enum    = 22;
+
+  repeated    int32 extend_repeated_int32    = 31;
+  repeated    int64 extend_repeated_int64    = 32;
+  repeated   uint32 extend_repeated_uint32   = 33;
+  repeated   uint64 extend_repeated_uint64   = 34;
+  repeated   sint32 extend_repeated_sint32   = 35;
+  repeated   sint64 extend_repeated_sint64   = 36;
+  repeated  fixed32 extend_repeated_fixed32  = 37;
+  repeated  fixed64 extend_repeated_fixed64  = 38;
+  repeated sfixed32 extend_repeated_sfixed32 = 39;
+  repeated sfixed64 extend_repeated_sfixed64 = 40;
+  repeated    float extend_repeated_float    = 41;
+  repeated   double extend_repeated_double   = 42;
+  repeated     bool extend_repeated_bool     = 43;
+  repeated   string extend_repeated_string   = 44;
+  repeated    bytes extend_repeated_bytes    = 45;
+  repeated ForeignEnum extend_repeated_foreign_enum    = 52;
+
+  repeated    int32 extend_packed_repeated_int32    = 61 [packed=true];
+  repeated    int64 extend_packed_repeated_int64    = 62 [packed=true];
+  repeated   uint32 extend_packed_repeated_uint32   = 63 [packed=true];
+  repeated   uint64 extend_packed_repeated_uint64   = 64 [packed=true];
+  repeated   sint32 extend_packed_repeated_sint32   = 65 [packed=true];
+  repeated   sint64 extend_packed_repeated_sint64   = 66 [packed=true];
+  repeated  fixed32 extend_packed_repeated_fixed32  = 67 [packed=true];
+  repeated  fixed64 extend_packed_repeated_fixed64  = 68 [packed=true];
+  repeated sfixed32 extend_packed_repeated_sfixed32 = 69 [packed=true];
+  repeated sfixed64 extend_packed_repeated_sfixed64 = 70 [packed=true];
+  repeated    float extend_packed_repeated_float    = 71 [packed=true];
+  repeated   double extend_packed_repeated_double   = 72 [packed=true];
+  repeated     bool extend_packed_repeated_bool     = 73 [packed=true];
+  repeated ForeignEnum extend_packed_repeated_foreign_enum    = 82
+      [packed=true];
+
+}
diff --git a/js/testempty.proto b/js/testempty.proto
new file mode 100644
index 00000000..960bce4e
--- /dev/null
+++ b/js/testempty.proto
@@ -0,0 +1,34 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+syntax = "proto2";
+
+package javatests.com.google.apps.jspb;
+
diff --git a/objectivec/google/protobuf/Any.pbobjc.h b/objectivec/google/protobuf/Any.pbobjc.h
index d2261ee4..9866b5b1 100644
--- a/objectivec/google/protobuf/Any.pbobjc.h
+++ b/objectivec/google/protobuf/Any.pbobjc.h
@@ -34,6 +34,7 @@ typedef GPB_ENUM(GPBAny_FieldNumber) {
 // `Any` contains an arbitrary serialized message along with a URL
 // that describes the type of the serialized message.
 //
+//
 // JSON
 // ====
 // The JSON representation of an `Any` value uses the regular
@@ -54,8 +55,8 @@ typedef GPB_ENUM(GPBAny_FieldNumber) {
 //
 // If the embedded message type is well-known and has a custom JSON
 // representation, that representation will be embedded adding a field
-// `value` which holds the custom JSON in addition to the the `@type`
-// field. Example (for message [google.protobuf.Duration][google.protobuf.Duration]):
+// `value` which holds the custom JSON in addition to the `@type`
+// field. Example (for message [google.protobuf.Duration][]):
 //
 //     {
 //       "@type": "type.googleapis.com/google.protobuf.Duration",
@@ -72,7 +73,7 @@ typedef GPB_ENUM(GPBAny_FieldNumber) {
 // * If no schema is provided, `https` is assumed.
 // * The last segment of the URL's path must represent the fully
 //   qualified name of the type (as in `path/google.protobuf.Duration`).
-// * An HTTP GET on the URL must yield a [google.protobuf.Type][google.protobuf.Type]
+// * An HTTP GET on the URL must yield a [google.protobuf.Type][]
 //   value in binary format, or produce an error.
 // * Applications are allowed to cache lookup results based on the
 //   URL, or have them precompiled into a binary to avoid any
diff --git a/objectivec/google/protobuf/Api.pbobjc.h b/objectivec/google/protobuf/Api.pbobjc.h
index c9dacfee..c3cf8e94 100644
--- a/objectivec/google/protobuf/Api.pbobjc.h
+++ b/objectivec/google/protobuf/Api.pbobjc.h
@@ -174,7 +174,6 @@ typedef GPB_ENUM(GPBMixin_FieldNumber) {
 //
 //     package google.storage.v2;
 //     service Storage {
-//       // (-- see AccessControl.GetAcl --)
 //       rpc GetAcl(GetAclRequest) returns (Acl);
 //
 //       // Get a data record.
diff --git a/objectivec/google/protobuf/FieldMask.pbobjc.h b/objectivec/google/protobuf/FieldMask.pbobjc.h
index 67cea4d6..4e4ec387 100644
--- a/objectivec/google/protobuf/FieldMask.pbobjc.h
+++ b/objectivec/google/protobuf/FieldMask.pbobjc.h
@@ -61,7 +61,7 @@ typedef GPB_ENUM(GPBFieldMask_FieldNumber) {
 //     z: 8
 //
 // The result will not contain specific values for fields x,y and z
-// (there value will be set to the default, and omitted in proto text
+// (their value will be set to the default, and omitted in proto text
 // output):
 //
 //
diff --git a/objectivec/google/protobuf/Type.pbobjc.h b/objectivec/google/protobuf/Type.pbobjc.h
index 65f1da46..e4c7a251 100644
--- a/objectivec/google/protobuf/Type.pbobjc.h
+++ b/objectivec/google/protobuf/Type.pbobjc.h
@@ -18,13 +18,13 @@ NS_ASSUME_NONNULL_BEGIN
 
 #pragma mark - Enum GPBSyntax
 
-// Syntax specifies the syntax in which a service element was defined.
+// The syntax in which a protocol buffer element is defined.
 typedef GPB_ENUM(GPBSyntax) {
   GPBSyntax_GPBUnrecognizedEnumeratorValue = kGPBUnrecognizedEnumeratorValue,
-  // Syntax "proto2"
+  // Syntax `proto2`.
   GPBSyntax_SyntaxProto2 = 0,
 
-  // Syntax "proto3"
+  // Syntax `proto3`.
   GPBSyntax_SyntaxProto3 = 1,
 };
 
@@ -34,7 +34,7 @@ BOOL GPBSyntax_IsValidValue(int32_t value);
 
 #pragma mark - Enum GPBField_Kind
 
-// Kind represents a basic field type.
+// Basic field types.
 typedef GPB_ENUM(GPBField_Kind) {
   GPBField_Kind_GPBUnrecognizedEnumeratorValue = kGPBUnrecognizedEnumeratorValue,
   // Field type unknown.
@@ -67,7 +67,7 @@ typedef GPB_ENUM(GPBField_Kind) {
   // Field type string.
   GPBField_Kind_TypeString = 9,
 
-  // Field type group (deprecated proto2 type)
+  // Field type group. Proto2 syntax only, and deprecated.
   GPBField_Kind_TypeGroup = 10,
 
   // Field type message.
@@ -101,17 +101,16 @@ BOOL GPBField_Kind_IsValidValue(int32_t value);
 
 #pragma mark - Enum GPBField_Cardinality
 
-// Cardinality represents whether a field is optional, required, or
-// repeated.
+// Whether a field is optional, required, or repeated.
 typedef GPB_ENUM(GPBField_Cardinality) {
   GPBField_Cardinality_GPBUnrecognizedEnumeratorValue = kGPBUnrecognizedEnumeratorValue,
-  // The field cardinality is unknown. Typically an error condition.
+  // For fields with unknown cardinality.
   GPBField_Cardinality_CardinalityUnknown = 0,
 
   // For optional fields.
   GPBField_Cardinality_CardinalityOptional = 1,
 
-  // For required fields. Not used for proto3.
+  // For required fields. Proto2 syntax only.
   GPBField_Cardinality_CardinalityRequired = 2,
 
   // For repeated fields.
@@ -144,7 +143,7 @@ typedef GPB_ENUM(GPBType_FieldNumber) {
   GPBType_FieldNumber_Syntax = 6,
 };
 
-// A light-weight descriptor for a proto message type.
+// A protocol buffer message type.
 @interface GPBType : GPBMessage
 
 // The fully qualified message name.
@@ -155,12 +154,12 @@ typedef GPB_ENUM(GPBType_FieldNumber) {
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *fieldsArray;
 @property(nonatomic, readonly) NSUInteger fieldsArray_Count;
 
-// The list of oneof definitions.
+// The list of types appearing in `oneof` definitions in this type.
 // |oneofsArray| contains |NSString|
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *oneofsArray;
 @property(nonatomic, readonly) NSUInteger oneofsArray_Count;
 
-// The proto options.
+// The protocol buffer options.
 // |optionsArray| contains |GPBOption|
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *optionsArray;
 @property(nonatomic, readonly) NSUInteger optionsArray_Count;
@@ -189,41 +188,46 @@ typedef GPB_ENUM(GPBField_FieldNumber) {
   GPBField_FieldNumber_Packed = 8,
   GPBField_FieldNumber_OptionsArray = 9,
   GPBField_FieldNumber_JsonName = 10,
+  GPBField_FieldNumber_DefaultValue = 11,
 };
 
-// Field represents a single field of a message type.
+// A single field of a message type.
 @interface GPBField : GPBMessage
 
-// The field kind.
+// The field type.
 @property(nonatomic, readwrite) GPBField_Kind kind;
 
-// The field cardinality, i.e. optional/required/repeated.
+// The field cardinality.
 @property(nonatomic, readwrite) GPBField_Cardinality cardinality;
 
-// The proto field number.
+// The field number.
 @property(nonatomic, readwrite) int32_t number;
 
 // The field name.
 @property(nonatomic, readwrite, copy, null_resettable) NSString *name;
 
-// The type URL (without the scheme) when the type is MESSAGE or ENUM,
-// such as `type.googleapis.com/google.protobuf.Empty`.
+// The field type URL, without the scheme, for message or enumeration
+// types. Example: `"type.googleapis.com/google.protobuf.Timestamp"`.
 @property(nonatomic, readwrite, copy, null_resettable) NSString *typeURL;
 
-// Index in Type.oneofs. Starts at 1. Zero means no oneof mapping.
+// The index of the field type in `Type.oneofs`, for message or enumeration
+// types. The first type has index 1; zero means the type is not in the list.
 @property(nonatomic, readwrite) int32_t oneofIndex;
 
 // Whether to use alternative packed wire representation.
 @property(nonatomic, readwrite) BOOL packed;
 
-// The proto options.
+// The protocol buffer options.
 // |optionsArray| contains |GPBOption|
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *optionsArray;
 @property(nonatomic, readonly) NSUInteger optionsArray_Count;
 
-// The JSON name for this field.
+// The field JSON name.
 @property(nonatomic, readwrite, copy, null_resettable) NSString *jsonName;
 
+// The string value of the default value of this field. Proto2 syntax only.
+@property(nonatomic, readwrite, copy, null_resettable) NSString *defaultValue;
+
 @end
 
 int32_t GPBField_Kind_RawValue(GPBField *message);
@@ -253,7 +257,7 @@ typedef GPB_ENUM(GPBEnum_FieldNumber) {
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *enumvalueArray;
 @property(nonatomic, readonly) NSUInteger enumvalueArray_Count;
 
-// Proto options for the enum type.
+// Protocol buffer options.
 // |optionsArray| contains |GPBOption|
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *optionsArray;
 @property(nonatomic, readonly) NSUInteger optionsArray_Count;
@@ -287,7 +291,7 @@ typedef GPB_ENUM(GPBEnumValue_FieldNumber) {
 // Enum value number.
 @property(nonatomic, readwrite) int32_t number;
 
-// Proto options for the enum value.
+// Protocol buffer options.
 // |optionsArray| contains |GPBOption|
 @property(nonatomic, readwrite, strong, null_resettable) NSMutableArray *optionsArray;
 @property(nonatomic, readonly) NSUInteger optionsArray_Count;
@@ -301,13 +305,14 @@ typedef GPB_ENUM(GPBOption_FieldNumber) {
   GPBOption_FieldNumber_Value = 2,
 };
 
-// Proto option attached to messages/fields/enums etc.
+// A protocol buffer option, which can be attached to a message, field,
+// enumeration, etc.
 @interface GPBOption : GPBMessage
 
-// Proto option name.
+// The option's name. For example, `"java_package"`.
 @property(nonatomic, readwrite, copy, null_resettable) NSString *name;
 
-// Proto option value.
+// The option's value. For example, `"com.google.protobuf"`.
 @property(nonatomic, readwrite) BOOL hasValue;
 @property(nonatomic, readwrite, strong, null_resettable) GPBAny *value;
 
diff --git a/python/google/protobuf/descriptor.py b/python/google/protobuf/descriptor.py
index 2bf36532..5f613c88 100755
--- a/python/google/protobuf/descriptor.py
+++ b/python/google/protobuf/descriptor.py
@@ -786,25 +786,33 @@ class FileDescriptor(DescriptorBase):
   message_types_by_name: Dict of message names of their descriptors.
   enum_types_by_name: Dict of enum names and their descriptors.
   extensions_by_name: Dict of extension names and their descriptors.
+  pool: the DescriptorPool this descriptor belongs to.  When not passed to the
+    constructor, the global default pool is used.
   """
 
   if _USE_C_DESCRIPTORS:
     _C_DESCRIPTOR_CLASS = _message.FileDescriptor
 
     def __new__(cls, name, package, options=None, serialized_pb=None,
-                dependencies=None, syntax=None):
+                dependencies=None, syntax=None, pool=None):
       # FileDescriptor() is called from various places, not only from generated
       # files, to register dynamic proto files and messages.
       if serialized_pb:
+        # TODO(amauryfa): use the pool passed as argument. This will work only
+        # for C++-implemented DescriptorPools.
         return _message.default_pool.AddSerializedFile(serialized_pb)
       else:
         return super(FileDescriptor, cls).__new__(cls)
 
   def __init__(self, name, package, options=None, serialized_pb=None,
-               dependencies=None, syntax=None):
+               dependencies=None, syntax=None, pool=None):
     """Constructor."""
     super(FileDescriptor, self).__init__(options, 'FileOptions')
 
+    if pool is None:
+      from google.protobuf import descriptor_pool
+      pool = descriptor_pool.Default()
+    self.pool = pool
     self.message_types_by_name = {}
     self.name = name
     self.package = package
diff --git a/python/google/protobuf/descriptor_database.py b/python/google/protobuf/descriptor_database.py
index b10021e9..1333f996 100644
--- a/python/google/protobuf/descriptor_database.py
+++ b/python/google/protobuf/descriptor_database.py
@@ -65,6 +65,7 @@ class DescriptorDatabase(object):
       raise DescriptorDatabaseConflictingDefinitionError(
           '%s already added, but with different descriptor.' % proto_name)
 
+    # Add the top-level Message, Enum and Extension descriptors to the index.
     package = file_desc_proto.package
     for message in file_desc_proto.message_type:
       self._file_desc_protos_by_symbol.update(
@@ -72,6 +73,9 @@ class DescriptorDatabase(object):
     for enum in file_desc_proto.enum_type:
       self._file_desc_protos_by_symbol[
           '.'.join((package, enum.name))] = file_desc_proto
+    for extension in file_desc_proto.extension:
+      self._file_desc_protos_by_symbol[
+          '.'.join((package, extension.name))] = file_desc_proto
 
   def FindFileByName(self, name):
     """Finds the file descriptor proto by file name.
diff --git a/python/google/protobuf/descriptor_pool.py b/python/google/protobuf/descriptor_pool.py
index 6a1b4b5e..3e80795c 100644
--- a/python/google/protobuf/descriptor_pool.py
+++ b/python/google/protobuf/descriptor_pool.py
@@ -83,6 +83,12 @@ def _NormalizeFullyQualifiedName(name):
 class DescriptorPool(object):
   """A collection of protobufs dynamically constructed by descriptor protos."""
 
+  if _USE_C_DESCRIPTORS:
+
+    def __new__(cls, descriptor_db=None):
+      # pylint: disable=protected-access
+      return descriptor._message.DescriptorPool(descriptor_db)
+
   def __init__(self, descriptor_db=None):
     """Initializes a Pool of proto buffs.
 
@@ -264,6 +270,39 @@ class DescriptorPool(object):
       self.FindFileContainingSymbol(full_name)
     return self._enum_descriptors[full_name]
 
+  def FindFieldByName(self, full_name):
+    """Loads the named field descriptor from the pool.
+
+    Args:
+      full_name: The full name of the field descriptor to load.
+
+    Returns:
+      The field descriptor for the named field.
+    """
+    full_name = _NormalizeFullyQualifiedName(full_name)
+    message_name, _, field_name = full_name.rpartition('.')
+    message_descriptor = self.FindMessageTypeByName(message_name)
+    return message_descriptor.fields_by_name[field_name]
+
+  def FindExtensionByName(self, full_name):
+    """Loads the named extension descriptor from the pool.
+
+    Args:
+      full_name: The full name of the extension descriptor to load.
+
+    Returns:
+      A FieldDescriptor, describing the named extension.
+    """
+    full_name = _NormalizeFullyQualifiedName(full_name)
+    message_name, _, extension_name = full_name.rpartition('.')
+    try:
+      # Most extensions are nested inside a message.
+      scope = self.FindMessageTypeByName(message_name)
+    except KeyError:
+      # Some extensions are defined at file scope.
+      scope = self.FindFileContainingSymbol(full_name)
+    return scope.extensions_by_name[extension_name]
+
   def _ConvertFileProtoToFileDescriptor(self, file_proto):
     """Creates a FileDescriptor from a proto or returns a cached copy.
 
@@ -282,6 +321,7 @@ class DescriptorPool(object):
       direct_deps = [self.FindFileByName(n) for n in file_proto.dependency]
 
       file_descriptor = descriptor.FileDescriptor(
+          pool=self,
           name=file_proto.name,
           package=file_proto.package,
           syntax=file_proto.syntax,
@@ -598,10 +638,24 @@ class DescriptorPool(object):
         field_desc.default_value = text_encoding.CUnescape(
             field_proto.default_value)
       else:
+        # All other types are of the "int" type.
         field_desc.default_value = int(field_proto.default_value)
     else:
       field_desc.has_default_value = False
-      field_desc.default_value = None
+      if (field_proto.type == descriptor.FieldDescriptor.TYPE_DOUBLE or
+          field_proto.type == descriptor.FieldDescriptor.TYPE_FLOAT):
+        field_desc.default_value = 0.0
+      elif field_proto.type == descriptor.FieldDescriptor.TYPE_STRING:
+        field_desc.default_value = u''
+      elif field_proto.type == descriptor.FieldDescriptor.TYPE_BOOL:
+        field_desc.default_value = False
+      elif field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
+        field_desc.default_value = field_desc.enum_type.values[0].number
+      elif field_proto.type == descriptor.FieldDescriptor.TYPE_BYTES:
+        field_desc.default_value = b''
+      else:
+        # All other types are of the "int" type.
+        field_desc.default_value = 0
 
     field_desc.type = field_proto.type
 
@@ -680,3 +734,16 @@ class DescriptorPool(object):
 
 def _PrefixWithDot(name):
   return name if name.startswith('.') else '.%s' % name
+
+
+if _USE_C_DESCRIPTORS:
+  # TODO(amauryfa): This pool could be constructed from Python code, when we
+  # support a flag like 'use_cpp_generated_pool=True'.
+  # pylint: disable=protected-access
+  _DEFAULT = descriptor._message.default_pool
+else:
+  _DEFAULT = DescriptorPool()
+
+
+def Default():
+  return _DEFAULT
diff --git a/python/google/protobuf/internal/any_test.proto b/python/google/protobuf/internal/any_test.proto
new file mode 100644
index 00000000..cd641ca0
--- /dev/null
+++ b/python/google/protobuf/internal/any_test.proto
@@ -0,0 +1,42 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: jieluo@google.com (Jie Luo)
+
+syntax = "proto3";
+
+package google.protobuf.internal;
+
+import "google/protobuf/any.proto";
+
+message TestAny {
+  google.protobuf.Any value = 1;
+  int32 int_value = 2;
+}
diff --git a/python/google/protobuf/internal/containers.py b/python/google/protobuf/internal/containers.py
index 9c8275eb..97cdd848 100755
--- a/python/google/protobuf/internal/containers.py
+++ b/python/google/protobuf/internal/containers.py
@@ -464,6 +464,9 @@ class ScalarMap(MutableMapping):
       return val
 
   def __contains__(self, item):
+    # We check the key's type to match the strong-typing flavor of the API.
+    # Also this makes it easier to match the behavior of the C++ implementation.
+    self._key_checker.CheckValue(item)
     return item in self._values
 
   # We need to override this explicitly, because our defaultdict-like behavior
@@ -491,10 +494,20 @@ class ScalarMap(MutableMapping):
   def __iter__(self):
     return iter(self._values)
 
+  def __repr__(self):
+    return repr(self._values)
+
   def MergeFrom(self, other):
     self._values.update(other._values)
     self._message_listener.Modified()
 
+  def InvalidateIterators(self):
+    # It appears that the only way to reliably invalidate iterators to
+    # self._values is to ensure that its size changes.
+    original = self._values
+    self._values = original.copy()
+    original[None] = None
+
   # This is defined in the abstract base, but we can do it much more cheaply.
   def clear(self):
     self._values.clear()
@@ -576,12 +589,22 @@ class MessageMap(MutableMapping):
   def __iter__(self):
     return iter(self._values)
 
+  def __repr__(self):
+    return repr(self._values)
+
   def MergeFrom(self, other):
     for key in other:
       self[key].MergeFrom(other[key])
     # self._message_listener.Modified() not required here, because
     # mutations to submessages already propagate.
 
+  def InvalidateIterators(self):
+    # It appears that the only way to reliably invalidate iterators to
+    # self._values is to ensure that its size changes.
+    original = self._values
+    self._values = original.copy()
+    original[None] = None
+
   # This is defined in the abstract base, but we can do it much more cheaply.
   def clear(self):
     self._values.clear()
diff --git a/python/google/protobuf/internal/descriptor_pool_test.py b/python/google/protobuf/internal/descriptor_pool_test.py
index da9a78db..f1d6bf99 100644
--- a/python/google/protobuf/internal/descriptor_pool_test.py
+++ b/python/google/protobuf/internal/descriptor_pool_test.py
@@ -40,6 +40,8 @@ try:
   import unittest2 as unittest
 except ImportError:
   import unittest
+from google.protobuf import unittest_import_pb2
+from google.protobuf import unittest_import_public_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import descriptor_pb2
 from google.protobuf.internal import api_implementation
@@ -51,13 +53,17 @@ from google.protobuf.internal import test_util
 from google.protobuf import descriptor
 from google.protobuf import descriptor_database
 from google.protobuf import descriptor_pool
+from google.protobuf import message_factory
 from google.protobuf import symbol_database
 
 
 class DescriptorPoolTest(unittest.TestCase):
 
+  def CreatePool(self):
+    return descriptor_pool.DescriptorPool()
+
   def setUp(self):
-    self.pool = descriptor_pool.DescriptorPool()
+    self.pool = self.CreatePool()
     self.factory_test1_fd = descriptor_pb2.FileDescriptorProto.FromString(
         factory_test1_pb2.DESCRIPTOR.serialized_pb)
     self.factory_test2_fd = descriptor_pb2.FileDescriptorProto.FromString(
@@ -89,7 +95,7 @@ class DescriptorPoolTest(unittest.TestCase):
         'google.protobuf.python.internal.Factory1Message')
     self.assertIsInstance(file_desc1, descriptor.FileDescriptor)
     self.assertEqual('google/protobuf/internal/factory_test1.proto',
-                      file_desc1.name)
+                     file_desc1.name)
     self.assertEqual('google.protobuf.python.internal', file_desc1.package)
     self.assertIn('Factory1Message', file_desc1.message_types_by_name)
 
@@ -97,7 +103,7 @@ class DescriptorPoolTest(unittest.TestCase):
         'google.protobuf.python.internal.Factory2Message')
     self.assertIsInstance(file_desc2, descriptor.FileDescriptor)
     self.assertEqual('google/protobuf/internal/factory_test2.proto',
-                      file_desc2.name)
+                     file_desc2.name)
     self.assertEqual('google.protobuf.python.internal', file_desc2.package)
     self.assertIn('Factory2Message', file_desc2.message_types_by_name)
 
@@ -111,7 +117,7 @@ class DescriptorPoolTest(unittest.TestCase):
     self.assertIsInstance(msg1, descriptor.Descriptor)
     self.assertEqual('Factory1Message', msg1.name)
     self.assertEqual('google.protobuf.python.internal.Factory1Message',
-                      msg1.full_name)
+                     msg1.full_name)
     self.assertEqual(None, msg1.containing_type)
 
     nested_msg1 = msg1.nested_types[0]
@@ -132,7 +138,7 @@ class DescriptorPoolTest(unittest.TestCase):
     self.assertIsInstance(msg2, descriptor.Descriptor)
     self.assertEqual('Factory2Message', msg2.name)
     self.assertEqual('google.protobuf.python.internal.Factory2Message',
-                      msg2.full_name)
+                     msg2.full_name)
     self.assertIsNone(msg2.containing_type)
 
     nested_msg2 = msg2.nested_types[0]
@@ -223,6 +229,37 @@ class DescriptorPoolTest(unittest.TestCase):
     with self.assertRaises(KeyError):
       self.pool.FindEnumTypeByName('Does not exist')
 
+  def testFindFieldByName(self):
+    field = self.pool.FindFieldByName(
+        'google.protobuf.python.internal.Factory1Message.list_value')
+    self.assertEqual(field.name, 'list_value')
+    self.assertEqual(field.label, field.LABEL_REPEATED)
+    with self.assertRaises(KeyError):
+      self.pool.FindFieldByName('Does not exist')
+
+  def testFindExtensionByName(self):
+    # An extension defined in a message.
+    extension = self.pool.FindExtensionByName(
+        'google.protobuf.python.internal.Factory2Message.one_more_field')
+    self.assertEqual(extension.name, 'one_more_field')
+    # An extension defined at file scope.
+    extension = self.pool.FindExtensionByName(
+        'google.protobuf.python.internal.another_field')
+    self.assertEqual(extension.name, 'another_field')
+    self.assertEqual(extension.number, 1002)
+    with self.assertRaises(KeyError):
+      self.pool.FindFieldByName('Does not exist')
+
+  def testExtensionsAreNotFields(self):
+    with self.assertRaises(KeyError):
+      self.pool.FindFieldByName('google.protobuf.python.internal.another_field')
+    with self.assertRaises(KeyError):
+      self.pool.FindFieldByName(
+          'google.protobuf.python.internal.Factory2Message.one_more_field')
+    with self.assertRaises(KeyError):
+      self.pool.FindExtensionByName(
+          'google.protobuf.python.internal.Factory1Message.list_value')
+
   def testUserDefinedDB(self):
     db = descriptor_database.DescriptorDatabase()
     self.pool = descriptor_pool.DescriptorPool(db)
@@ -231,8 +268,7 @@ class DescriptorPoolTest(unittest.TestCase):
     self.testFindMessageTypeByName()
 
   def testAddSerializedFile(self):
-    db = descriptor_database.DescriptorDatabase()
-    self.pool = descriptor_pool.DescriptorPool(db)
+    self.pool = descriptor_pool.DescriptorPool()
     self.pool.AddSerializedFile(self.factory_test1_fd.SerializeToString())
     self.pool.AddSerializedFile(self.factory_test2_fd.SerializeToString())
     self.testFindMessageTypeByName()
@@ -274,6 +310,56 @@ class DescriptorPoolTest(unittest.TestCase):
         'google/protobuf/internal/descriptor_pool_test1.proto')
     _CheckDefaultValue(file_descriptor)
 
+  def testDefaultValueForCustomMessages(self):
+    """Check the value returned by non-existent fields."""
+    def _CheckValueAndType(value, expected_value, expected_type):
+      self.assertEqual(value, expected_value)
+      self.assertIsInstance(value, expected_type)
+
+    def _CheckDefaultValues(msg):
+      try:
+        int64 = long
+      except NameError:  # Python3
+        int64 = int
+      try:
+        unicode_type = unicode
+      except NameError:  # Python3
+        unicode_type = str
+      _CheckValueAndType(msg.optional_int32, 0, int)
+      _CheckValueAndType(msg.optional_uint64, 0, (int64, int))
+      _CheckValueAndType(msg.optional_float, 0, (float, int))
+      _CheckValueAndType(msg.optional_double, 0, (float, int))
+      _CheckValueAndType(msg.optional_bool, False, bool)
+      _CheckValueAndType(msg.optional_string, u'', unicode_type)
+      _CheckValueAndType(msg.optional_bytes, b'', bytes)
+      _CheckValueAndType(msg.optional_nested_enum, msg.FOO, int)
+    # First for the generated message
+    _CheckDefaultValues(unittest_pb2.TestAllTypes())
+    # Then for a message built with from the DescriptorPool.
+    pool = descriptor_pool.DescriptorPool()
+    pool.Add(descriptor_pb2.FileDescriptorProto.FromString(
+        unittest_import_public_pb2.DESCRIPTOR.serialized_pb))
+    pool.Add(descriptor_pb2.FileDescriptorProto.FromString(
+        unittest_import_pb2.DESCRIPTOR.serialized_pb))
+    pool.Add(descriptor_pb2.FileDescriptorProto.FromString(
+        unittest_pb2.DESCRIPTOR.serialized_pb))
+    message_class = message_factory.MessageFactory(pool).GetPrototype(
+        pool.FindMessageTypeByName(
+            unittest_pb2.TestAllTypes.DESCRIPTOR.full_name))
+    _CheckDefaultValues(message_class())
+
+
+@unittest.skipIf(api_implementation.Type() != 'cpp',
+                            'explicit tests of the C++ implementation')
+class CppDescriptorPoolTest(DescriptorPoolTest):
+  # TODO(amauryfa): remove when descriptor_pool.DescriptorPool() creates true
+  # C++ descriptor pool object for C++ implementation.
+
+  def CreatePool(self):
+    # pylint: disable=g-import-not-at-top
+    from google.protobuf.pyext import _message
+    return _message.DescriptorPool()
+
 
 class ProtoFile(object):
 
@@ -468,6 +554,8 @@ class AddDescriptorTest(unittest.TestCase):
         pool.FindFileContainingSymbol(
             prefix + 'protobuf_unittest.TestAllTypes.NestedMessage').name)
 
+  @unittest.skipIf(api_implementation.Type() == 'cpp',
+                    'With the cpp implementation, Add() must be called first')
   def testMessage(self):
     self._TestMessage('')
     self._TestMessage('.')
@@ -502,10 +590,14 @@ class AddDescriptorTest(unittest.TestCase):
         pool.FindFileContainingSymbol(
             prefix + 'protobuf_unittest.TestAllTypes.NestedEnum').name)
 
+  @unittest.skipIf(api_implementation.Type() == 'cpp',
+                    'With the cpp implementation, Add() must be called first')
   def testEnum(self):
     self._TestEnum('')
     self._TestEnum('.')
 
+  @unittest.skipIf(api_implementation.Type() == 'cpp',
+                    'With the cpp implementation, Add() must be called first')
   def testFile(self):
     pool = descriptor_pool.DescriptorPool()
     pool.AddFileDescriptor(unittest_pb2.DESCRIPTOR)
@@ -520,6 +612,76 @@ class AddDescriptorTest(unittest.TestCase):
       pool.FindFileContainingSymbol(
           'protobuf_unittest.TestAllTypes')
 
+  def _GetDescriptorPoolClass(self):
+    # Test with both implementations of descriptor pools.
+    if api_implementation.Type() == 'cpp':
+      # pylint: disable=g-import-not-at-top
+      from google.protobuf.pyext import _message
+      return _message.DescriptorPool
+    else:
+      return descriptor_pool.DescriptorPool
+
+  def testEmptyDescriptorPool(self):
+    # Check that an empty DescriptorPool() contains no message.
+    pool = self._GetDescriptorPoolClass()()
+    proto_file_name = descriptor_pb2.DESCRIPTOR.name
+    self.assertRaises(KeyError, pool.FindFileByName, proto_file_name)
+    # Add the above file to the pool
+    file_descriptor = descriptor_pb2.FileDescriptorProto()
+    descriptor_pb2.DESCRIPTOR.CopyToProto(file_descriptor)
+    pool.Add(file_descriptor)
+    # Now it exists.
+    self.assertTrue(pool.FindFileByName(proto_file_name))
+
+  def testCustomDescriptorPool(self):
+    # Create a new pool, and add a file descriptor.
+    pool = self._GetDescriptorPoolClass()()
+    file_desc = descriptor_pb2.FileDescriptorProto(
+        name='some/file.proto', package='package')
+    file_desc.message_type.add(name='Message')
+    pool.Add(file_desc)
+    self.assertEqual(pool.FindFileByName('some/file.proto').name,
+                     'some/file.proto')
+    self.assertEqual(pool.FindMessageTypeByName('package.Message').name,
+                     'Message')
+
+
+@unittest.skipIf(
+    api_implementation.Type() != 'cpp',
+    'default_pool is only supported by the C++ implementation')
+class DefaultPoolTest(unittest.TestCase):
+
+  def testFindMethods(self):
+    # pylint: disable=g-import-not-at-top
+    from google.protobuf.pyext import _message
+    pool = _message.default_pool
+    self.assertIs(
+        pool.FindFileByName('google/protobuf/unittest.proto'),
+        unittest_pb2.DESCRIPTOR)
+    self.assertIs(
+        pool.FindMessageTypeByName('protobuf_unittest.TestAllTypes'),
+        unittest_pb2.TestAllTypes.DESCRIPTOR)
+    self.assertIs(
+        pool.FindFieldByName('protobuf_unittest.TestAllTypes.optional_int32'),
+        unittest_pb2.TestAllTypes.DESCRIPTOR.fields_by_name['optional_int32'])
+    self.assertIs(
+        pool.FindExtensionByName('protobuf_unittest.optional_int32_extension'),
+        unittest_pb2.DESCRIPTOR.extensions_by_name['optional_int32_extension'])
+    self.assertIs(
+        pool.FindEnumTypeByName('protobuf_unittest.ForeignEnum'),
+        unittest_pb2.ForeignEnum.DESCRIPTOR)
+    self.assertIs(
+        pool.FindOneofByName('protobuf_unittest.TestAllTypes.oneof_field'),
+        unittest_pb2.TestAllTypes.DESCRIPTOR.oneofs_by_name['oneof_field'])
+
+  def testAddFileDescriptor(self):
+    # pylint: disable=g-import-not-at-top
+    from google.protobuf.pyext import _message
+    pool = _message.default_pool
+    file_desc = descriptor_pb2.FileDescriptorProto(name='some/file.proto')
+    pool.Add(file_desc)
+    pool.AddSerializedFile(file_desc.SerializeToString())
+
 
 TEST1_FILE = ProtoFile(
     'google/protobuf/internal/descriptor_pool_test1.proto',
diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index 99afee63..fee09a56 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -47,6 +47,7 @@ from google.protobuf import descriptor_pb2
 from google.protobuf.internal import api_implementation
 from google.protobuf.internal import test_util
 from google.protobuf import descriptor
+from google.protobuf import descriptor_pool
 from google.protobuf import symbol_database
 from google.protobuf import text_format
 
@@ -75,9 +76,9 @@ class DescriptorTest(unittest.TestCase):
     enum_proto.value.add(name='FOREIGN_BAR', number=5)
     enum_proto.value.add(name='FOREIGN_BAZ', number=6)
 
-    descriptor_pool = symbol_database.Default().pool
-    descriptor_pool.Add(file_proto)
-    self.my_file = descriptor_pool.FindFileByName(file_proto.name)
+    self.pool = self.GetDescriptorPool()
+    self.pool.Add(file_proto)
+    self.my_file = self.pool.FindFileByName(file_proto.name)
     self.my_message = self.my_file.message_types_by_name[message_proto.name]
     self.my_enum = self.my_message.enum_types_by_name[enum_proto.name]
 
@@ -97,6 +98,9 @@ class DescriptorTest(unittest.TestCase):
             self.my_method
         ])
 
+  def GetDescriptorPool(self):
+    return symbol_database.Default().pool
+
   def testEnumValueName(self):
     self.assertEqual(self.my_message.EnumValueName('ForeignEnum', 4),
                      'FOREIGN_FOO')
@@ -393,6 +397,9 @@ class DescriptorTest(unittest.TestCase):
   def testFileDescriptor(self):
     self.assertEqual(self.my_file.name, 'some/filename/some.proto')
     self.assertEqual(self.my_file.package, 'protobuf_unittest')
+    self.assertEqual(self.my_file.pool, self.pool)
+    # Generated modules also belong to the default pool.
+    self.assertEqual(unittest_pb2.DESCRIPTOR.pool, descriptor_pool.Default())
 
   @unittest.skipIf(
       api_implementation.Type() != 'cpp' or api_implementation.Version() != 2,
@@ -407,6 +414,13 @@ class DescriptorTest(unittest.TestCase):
       message_descriptor.fields.append(None)
 
 
+class NewDescriptorTest(DescriptorTest):
+  """Redo the same tests as above, but with a separate DescriptorPool."""
+
+  def GetDescriptorPool(self):
+    return descriptor_pool.DescriptorPool()
+
+
 class GeneratedDescriptorTest(unittest.TestCase):
   """Tests for the properties of descriptors in generated code."""
 
diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
index 69197865..be3ad11a 100644
--- a/python/google/protobuf/internal/json_format_test.py
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -42,6 +42,7 @@ try:
   import unittest2 as unittest
 except ImportError:
   import unittest
+from google.protobuf.internal import well_known_types
 from google.protobuf import json_format
 from google.protobuf.util import json_format_proto3_pb2
 
@@ -269,15 +270,15 @@ class JsonFormatTest(JsonFormatBase):
                    '}'))
     parsed_message = json_format_proto3_pb2.TestTimestamp()
     self.CheckParseBack(message, parsed_message)
-    text = (r'{"value": "1972-01-01T01:00:00.01+08:00",'
+    text = (r'{"value": "1970-01-01T00:00:00.01+08:00",'
             r'"repeatedValue":['
-            r'  "1972-01-01T01:00:00.01+08:30",'
-            r'  "1972-01-01T01:00:00.01-01:23"]}')
+            r'  "1970-01-01T00:00:00.01+08:30",'
+            r'  "1970-01-01T00:00:00.01-01:23"]}')
     json_format.Parse(text, parsed_message)
-    self.assertEqual(parsed_message.value.seconds, 63104400)
+    self.assertEqual(parsed_message.value.seconds, -8 * 3600)
     self.assertEqual(parsed_message.value.nanos, 10000000)
-    self.assertEqual(parsed_message.repeated_value[0].seconds, 63106200)
-    self.assertEqual(parsed_message.repeated_value[1].seconds, 63070620)
+    self.assertEqual(parsed_message.repeated_value[0].seconds, -8.5 * 3600)
+    self.assertEqual(parsed_message.repeated_value[1].seconds, 3600 + 23 * 60)
 
   def testDurationMessage(self):
     message = json_format_proto3_pb2.TestDuration()
@@ -389,7 +390,7 @@ class JsonFormatTest(JsonFormatBase):
 
   def testParseEmptyText(self):
     self.CheckError('',
-                    r'Failed to load JSON: (Expecting value)|(No JSON)')
+                    r'Failed to load JSON: (Expecting value)|(No JSON).')
 
   def testParseBadEnumValue(self):
     self.CheckError(
@@ -414,7 +415,7 @@ class JsonFormatTest(JsonFormatBase):
     if sys.version_info < (2, 7):
       return
     self.CheckError('{"int32Value": 1,\n"int32Value":2}',
-                    'Failed to load JSON: duplicate key int32Value')
+                    'Failed to load JSON: duplicate key int32Value.')
 
   def testInvalidBoolValue(self):
     self.CheckError('{"boolValue": 1}',
@@ -431,39 +432,43 @@ class JsonFormatTest(JsonFormatBase):
                       json_format.Parse, text, message)
     self.CheckError('{"int32Value": 012345}',
                     (r'Failed to load JSON: Expecting \'?,\'? delimiter: '
-                     r'line 1'))
+                     r'line 1.'))
     self.CheckError('{"int32Value": 1.0}',
                     'Failed to parse int32Value field: '
-                    'Couldn\'t parse integer: 1.0')
+                    'Couldn\'t parse integer: 1.0.')
     self.CheckError('{"int32Value": " 1 "}',
                     'Failed to parse int32Value field: '
-                    'Couldn\'t parse integer: " 1 "')
+                    'Couldn\'t parse integer: " 1 ".')
+    self.CheckError('{"int32Value": "1 "}',
+                    'Failed to parse int32Value field: '
+                    'Couldn\'t parse integer: "1 ".')
     self.CheckError('{"int32Value": 12345678901234567890}',
                     'Failed to parse int32Value field: Value out of range: '
-                    '12345678901234567890')
+                    '12345678901234567890.')
     self.CheckError('{"int32Value": 1e5}',
                     'Failed to parse int32Value field: '
-                    'Couldn\'t parse integer: 100000.0')
+                    'Couldn\'t parse integer: 100000.0.')
     self.CheckError('{"uint32Value": -1}',
-                    'Failed to parse uint32Value field: Value out of range: -1')
+                    'Failed to parse uint32Value field: '
+                    'Value out of range: -1.')
 
   def testInvalidFloatValue(self):
     self.CheckError('{"floatValue": "nan"}',
                     'Failed to parse floatValue field: Couldn\'t '
-                    'parse float "nan", use "NaN" instead')
+                    'parse float "nan", use "NaN" instead.')
 
   def testInvalidBytesValue(self):
     self.CheckError('{"bytesValue": "AQI"}',
-                    'Failed to parse bytesValue field: Incorrect padding')
+                    'Failed to parse bytesValue field: Incorrect padding.')
     self.CheckError('{"bytesValue": "AQI*"}',
-                    'Failed to parse bytesValue field: Incorrect padding')
+                    'Failed to parse bytesValue field: Incorrect padding.')
 
   def testInvalidMap(self):
     message = json_format_proto3_pb2.TestMap()
     text = '{"int32Map": {"null": 2, "2": 3}}'
     self.assertRaisesRegexp(
         json_format.ParseError,
-        'Failed to parse int32Map field: Couldn\'t parse integer: "null"',
+        'Failed to parse int32Map field: invalid literal',
         json_format.Parse, text, message)
     text = '{"int32Map": {1: 2, "2": 3}}'
     self.assertRaisesRegexp(
@@ -474,7 +479,7 @@ class JsonFormatTest(JsonFormatBase):
     text = '{"boolMap": {"null": 1}}'
     self.assertRaisesRegexp(
         json_format.ParseError,
-        'Failed to parse boolMap field: Expect "true" or "false", not null.',
+        'Failed to parse boolMap field: Expected "true" or "false", not null.',
         json_format.Parse, text, message)
     if sys.version_info < (2, 7):
       return
@@ -490,30 +495,29 @@ class JsonFormatTest(JsonFormatBase):
     self.assertRaisesRegexp(
         json_format.ParseError,
         'time data \'10000-01-01T00:00:00\' does not match'
-        ' format \'%Y-%m-%dT%H:%M:%S\'',
+        ' format \'%Y-%m-%dT%H:%M:%S\'.',
         json_format.Parse, text, message)
     text = '{"value": "1970-01-01T00:00:00.0123456789012Z"}'
     self.assertRaisesRegexp(
-        json_format.ParseError,
-        'Failed to parse value field: Failed to parse Timestamp: '
+        well_known_types.ParseError,
         'nanos 0123456789012 more than 9 fractional digits.',
         json_format.Parse, text, message)
     text = '{"value": "1972-01-01T01:00:00.01+08"}'
     self.assertRaisesRegexp(
-        json_format.ParseError,
-        (r'Failed to parse value field: Invalid timezone offset value: \+08'),
+        well_known_types.ParseError,
+        (r'Invalid timezone offset value: \+08.'),
         json_format.Parse, text, message)
     # Time smaller than minimum time.
     text = '{"value": "0000-01-01T00:00:00Z"}'
     self.assertRaisesRegexp(
         json_format.ParseError,
-        'Failed to parse value field: year is out of range',
+        'Failed to parse value field: year is out of range.',
         json_format.Parse, text, message)
     # Time bigger than maxinum time.
     message.value.seconds = 253402300800
     self.assertRaisesRegexp(
-        json_format.SerializeToJsonError,
-        'Failed to serialize value field: year is out of range',
+        OverflowError,
+        'date value out of range',
         json_format.MessageToJson, message)
 
   def testInvalidOneof(self):
diff --git a/python/google/protobuf/internal/message_factory_test.py b/python/google/protobuf/internal/message_factory_test.py
index d760b898..2fbe5ea7 100644
--- a/python/google/protobuf/internal/message_factory_test.py
+++ b/python/google/protobuf/internal/message_factory_test.py
@@ -45,6 +45,7 @@ from google.protobuf import descriptor_database
 from google.protobuf import descriptor_pool
 from google.protobuf import message_factory
 
+
 class MessageFactoryTest(unittest.TestCase):
 
   def setUp(self):
@@ -104,8 +105,8 @@ class MessageFactoryTest(unittest.TestCase):
   def testGetMessages(self):
     # performed twice because multiple calls with the same input must be allowed
     for _ in range(2):
-      messages = message_factory.GetMessages([self.factory_test2_fd,
-                                              self.factory_test1_fd])
+      messages = message_factory.GetMessages([self.factory_test1_fd,
+                                              self.factory_test2_fd])
       self.assertTrue(
           set(['google.protobuf.python.internal.Factory2Message',
                'google.protobuf.python.internal.Factory1Message'],
@@ -116,7 +117,7 @@ class MessageFactoryTest(unittest.TestCase):
           set(['google.protobuf.python.internal.Factory2Message.one_more_field',
                'google.protobuf.python.internal.another_field'],
              ).issubset(
-                set(messages['google.protobuf.python.internal.Factory1Message']
+                 set(messages['google.protobuf.python.internal.Factory1Message']
                      ._extensions_by_name.keys())))
       factory_msg1 = messages['google.protobuf.python.internal.Factory1Message']
       msg1 = messages['google.protobuf.python.internal.Factory1Message']()
diff --git a/python/google/protobuf/internal/message_set_extensions.proto b/python/google/protobuf/internal/message_set_extensions.proto
index 702c8d07..14e5f193 100644
--- a/python/google/protobuf/internal/message_set_extensions.proto
+++ b/python/google/protobuf/internal/message_set_extensions.proto
@@ -54,6 +54,14 @@ message TestMessageSetExtension2 {
   optional string str = 25;
 }
 
+message TestMessageSetExtension3 {
+  optional string text = 35;
+}
+
+extend TestMessageSet {
+  optional TestMessageSetExtension3 message_set_extension3 = 98418655;
+}
+
 // This message was used to generate
 // //net/proto2/python/internal/testdata/message_set_message, but is commented
 // out since it must not actually exist in code, to simulate an "unknown"
diff --git a/python/google/protobuf/internal/message_test.py b/python/google/protobuf/internal/message_test.py
index 13c3caa6..d03f2d25 100755
--- a/python/google/protobuf/internal/message_test.py
+++ b/python/google/protobuf/internal/message_test.py
@@ -60,6 +60,7 @@ from google.protobuf.internal import _parameterized
 from google.protobuf import map_unittest_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import unittest_proto3_arena_pb2
+from google.protobuf.internal import any_test_pb2
 from google.protobuf.internal import api_implementation
 from google.protobuf.internal import packed_field_test_pb2
 from google.protobuf.internal import test_util
@@ -1279,12 +1280,13 @@ class Proto3Test(unittest.TestCase):
 
     self.assertIsInstance(msg.map_string_string['abc'], six.text_type)
 
-    # Accessing an unset key still throws TypeError of the type of the key
+    # Accessing an unset key still throws TypeError if the type of the key
     # is incorrect.
     with self.assertRaises(TypeError):
       msg.map_string_string[123]
 
-    self.assertFalse(123 in msg.map_string_string)
+    with self.assertRaises(TypeError):
+      123 in msg.map_string_string
 
   def testMapGet(self):
     # Need to test that get() properly returns the default, even though the dict
@@ -1591,31 +1593,49 @@ class Proto3Test(unittest.TestCase):
     # For the C++ implementation this tests the correctness of
     # ScalarMapContainer::Release()
     msg = map_unittest_pb2.TestMap()
-    map = msg.map_int32_int32
+    int32_map = msg.map_int32_int32
 
-    map[2] = 4
-    map[3] = 6
-    map[4] = 8
+    int32_map[2] = 4
+    int32_map[3] = 6
+    int32_map[4] = 8
 
     msg.ClearField('map_int32_int32')
+    self.assertEqual(b'', msg.SerializeToString())
     matching_dict = {2: 4, 3: 6, 4: 8}
-    self.assertMapIterEquals(map.items(), matching_dict)
+    self.assertMapIterEquals(int32_map.items(), matching_dict)
 
-  def testMapIterValidAfterFieldCleared(self):
-    # Map iterator needs to work even if field is cleared.
+  def testMessageMapValidAfterFieldCleared(self):
+    # Map needs to work even if field is cleared.
     # For the C++ implementation this tests the correctness of
     # ScalarMapContainer::Release()
     msg = map_unittest_pb2.TestMap()
+    int32_foreign_message = msg.map_int32_foreign_message
 
-    msg.map_int32_int32[2] = 4
-    msg.map_int32_int32[3] = 6
-    msg.map_int32_int32[4] = 8
+    int32_foreign_message[2].c = 5
 
-    it = msg.map_int32_int32.items()
+    msg.ClearField('map_int32_foreign_message')
+    self.assertEqual(b'', msg.SerializeToString())
+    self.assertTrue(2 in int32_foreign_message.keys())
+
+  def testMapIterInvalidatedByClearField(self):
+    # Map iterator is invalidated when field is cleared.
+    # But this case does need to not crash the interpreter.
+    # For the C++ implementation this tests the correctness of
+    # ScalarMapContainer::Release()
+    msg = map_unittest_pb2.TestMap()
+
+    it = iter(msg.map_int32_int32)
 
     msg.ClearField('map_int32_int32')
-    matching_dict = {2: 4, 3: 6, 4: 8}
-    self.assertMapIterEquals(it, matching_dict)
+    with self.assertRaises(RuntimeError):
+      for _ in it:
+        pass
+
+    it = iter(msg.map_int32_foreign_message)
+    msg.ClearField('map_int32_foreign_message')
+    with self.assertRaises(RuntimeError):
+      for _ in it:
+        pass
 
   def testMapDelete(self):
     msg = map_unittest_pb2.TestMap()
@@ -1646,6 +1666,37 @@ class Proto3Test(unittest.TestCase):
     msg.map_string_foreign_message['foo'].c = 5
     self.assertEqual(0, len(msg.FindInitializationErrors()))
 
+  def testAnyMessage(self):
+    # Creates and sets message.
+    msg = any_test_pb2.TestAny()
+    msg_descriptor = msg.DESCRIPTOR
+    all_types = unittest_pb2.TestAllTypes()
+    all_descriptor = all_types.DESCRIPTOR
+    all_types.repeated_string.append(u'\u00fc\ua71f')
+    # Packs to Any.
+    msg.value.Pack(all_types)
+    self.assertEqual(msg.value.type_url,
+                     'type.googleapis.com/%s' % all_descriptor.full_name)
+    self.assertEqual(msg.value.value,
+                     all_types.SerializeToString())
+    # Tests Is() method.
+    self.assertTrue(msg.value.Is(all_descriptor))
+    self.assertFalse(msg.value.Is(msg_descriptor))
+    # Unpacks Any.
+    unpacked_message = unittest_pb2.TestAllTypes()
+    self.assertTrue(msg.value.Unpack(unpacked_message))
+    self.assertEqual(all_types, unpacked_message)
+    # Unpacks to different type.
+    self.assertFalse(msg.value.Unpack(msg))
+    # Only Any messages have Pack method.
+    try:
+      msg.Pack(all_types)
+    except AttributeError:
+      pass
+    else:
+      raise AttributeError('%s should not have Pack method.' %
+                           msg_descriptor.full_name)
+
 
 
 class ValidTypeNamesTest(unittest.TestCase):
diff --git a/python/google/protobuf/internal/python_message.py b/python/google/protobuf/internal/python_message.py
index 2b87f704..87f60666 100755
--- a/python/google/protobuf/internal/python_message.py
+++ b/python/google/protobuf/internal/python_message.py
@@ -65,6 +65,7 @@ from google.protobuf.internal import encoder
 from google.protobuf.internal import enum_type_wrapper
 from google.protobuf.internal import message_listener as message_listener_mod
 from google.protobuf.internal import type_checkers
+from google.protobuf.internal import well_known_types
 from google.protobuf.internal import wire_format
 from google.protobuf import descriptor as descriptor_mod
 from google.protobuf import message as message_mod
@@ -72,6 +73,7 @@ from google.protobuf import symbol_database
 from google.protobuf import text_format
 
 _FieldDescriptor = descriptor_mod.FieldDescriptor
+_AnyFullTypeName = 'google.protobuf.Any'
 
 
 class GeneratedProtocolMessageType(type):
@@ -127,6 +129,8 @@ class GeneratedProtocolMessageType(type):
       Newly-allocated class.
     """
     descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
+    if descriptor.full_name in well_known_types.WKTBASES:
+      bases += (well_known_types.WKTBASES[descriptor.full_name],)
     _AddClassAttributesForNestedExtensions(descriptor, dictionary)
     _AddSlots(descriptor, dictionary)
 
@@ -261,7 +265,6 @@ def _IsMessageSetExtension(field):
           field.containing_type.has_options and
           field.containing_type.GetOptions().message_set_wire_format and
           field.type == _FieldDescriptor.TYPE_MESSAGE and
-          field.message_type == field.extension_scope and
           field.label == _FieldDescriptor.LABEL_OPTIONAL)
 
 
@@ -543,7 +546,8 @@ def _GetFieldByName(message_descriptor, field_name):
   try:
     return message_descriptor.fields_by_name[field_name]
   except KeyError:
-    raise ValueError('Protocol message has no "%s" field.' % field_name)
+    raise ValueError('Protocol message %s has no "%s" field.' %
+                     (message_descriptor.name, field_name))
 
 
 def _AddPropertiesForFields(descriptor, cls):
@@ -848,9 +852,15 @@ def _AddClearFieldMethod(message_descriptor, cls):
         else:
           return
       except KeyError:
-        raise ValueError('Protocol message has no "%s" field.' % field_name)
+        raise ValueError('Protocol message %s() has no "%s" field.' %
+                         (message_descriptor.name, field_name))
 
     if field in self._fields:
+      # To match the C++ implementation, we need to invalidate iterators
+      # for map fields when ClearField() happens.
+      if hasattr(self._fields[field], 'InvalidateIterators'):
+        self._fields[field].InvalidateIterators()
+
       # Note:  If the field is a sub-message, its listener will still point
       #   at us.  That's fine, because the worst than can happen is that it
       #   will call _Modified() and invalidate our byte size.  Big deal.
@@ -904,7 +914,19 @@ def _AddHasExtensionMethod(cls):
       return extension_handle in self._fields
   cls.HasExtension = HasExtension
 
-def _UnpackAny(msg):
+def _InternalUnpackAny(msg):
+  """Unpacks Any message and returns the unpacked message.
+
+  This internal method is differnt from public Any Unpack method which takes
+  the target message as argument. _InternalUnpackAny method does not have
+  target message type and need to find the message type in descriptor pool.
+
+  Args:
+    msg: An Any message to be unpacked.
+
+  Returns:
+    The unpacked message.
+  """
   type_url = msg.type_url
   db = symbol_database.Default()
 
@@ -935,9 +957,9 @@ def _AddEqualsMethod(message_descriptor, cls):
     if self is other:
       return True
 
-    if self.DESCRIPTOR.full_name == "google.protobuf.Any":
-      any_a = _UnpackAny(self)
-      any_b = _UnpackAny(other)
+    if self.DESCRIPTOR.full_name == _AnyFullTypeName:
+      any_a = _InternalUnpackAny(self)
+      any_b = _InternalUnpackAny(other)
       if any_a and any_b:
         return any_a == any_b
 
@@ -962,6 +984,13 @@ def _AddStrMethod(message_descriptor, cls):
   cls.__str__ = __str__
 
 
+def _AddReprMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def __repr__(self):
+    return text_format.MessageToString(self)
+  cls.__repr__ = __repr__
+
+
 def _AddUnicodeMethod(unused_message_descriptor, cls):
   """Helper for _AddMessageMethods()."""
 
@@ -1270,6 +1299,7 @@ def _AddMessageMethods(message_descriptor, cls):
   _AddClearMethod(message_descriptor, cls)
   _AddEqualsMethod(message_descriptor, cls)
   _AddStrMethod(message_descriptor, cls)
+  _AddReprMethod(message_descriptor, cls)
   _AddUnicodeMethod(message_descriptor, cls)
   _AddSetListenerMethod(cls)
   _AddByteSizeMethod(message_descriptor, cls)
@@ -1280,6 +1310,7 @@ def _AddMessageMethods(message_descriptor, cls):
   _AddMergeFromMethod(cls)
   _AddWhichOneofMethod(message_descriptor, cls)
 
+
 def _AddPrivateHelperMethods(message_descriptor, cls):
   """Adds implementation of private helper methods to cls."""
 
diff --git a/python/google/protobuf/internal/reflection_test.py b/python/google/protobuf/internal/reflection_test.py
index 8621d61e..752f2f5d 100755
--- a/python/google/protobuf/internal/reflection_test.py
+++ b/python/google/protobuf/internal/reflection_test.py
@@ -2394,8 +2394,10 @@ class SerializationTest(unittest.TestCase):
     extension_message2 = message_set_extensions_pb2.TestMessageSetExtension2
     extension1 = extension_message1.message_set_extension
     extension2 = extension_message2.message_set_extension
+    extension3 = message_set_extensions_pb2.message_set_extension3
     proto.Extensions[extension1].i = 123
     proto.Extensions[extension2].str = 'foo'
+    proto.Extensions[extension3].text = 'bar'
 
     # Serialize using the MessageSet wire format (this is specified in the
     # .proto file).
@@ -2407,7 +2409,7 @@ class SerializationTest(unittest.TestCase):
     self.assertEqual(
         len(serialized),
         raw.MergeFromString(serialized))
-    self.assertEqual(2, len(raw.item))
+    self.assertEqual(3, len(raw.item))
 
     message1 = message_set_extensions_pb2.TestMessageSetExtension1()
     self.assertEqual(
@@ -2421,6 +2423,12 @@ class SerializationTest(unittest.TestCase):
         message2.MergeFromString(raw.item[1].message))
     self.assertEqual('foo', message2.str)
 
+    message3 = message_set_extensions_pb2.TestMessageSetExtension3()
+    self.assertEqual(
+        len(raw.item[2].message),
+        message3.MergeFromString(raw.item[2].message))
+    self.assertEqual('bar', message3.text)
+
     # Deserialize using the MessageSet wire format.
     proto2 = message_set_extensions_pb2.TestMessageSet()
     self.assertEqual(
@@ -2428,6 +2436,7 @@ class SerializationTest(unittest.TestCase):
         proto2.MergeFromString(serialized))
     self.assertEqual(123, proto2.Extensions[extension1].i)
     self.assertEqual('foo', proto2.Extensions[extension2].str)
+    self.assertEqual('bar', proto2.Extensions[extension3].text)
 
     # Check byte size.
     self.assertEqual(proto2.ByteSize(), len(serialized))
@@ -2757,9 +2766,10 @@ class SerializationTest(unittest.TestCase):
   def testInitArgsUnknownFieldName(self):
     def InitalizeEmptyMessageWithExtraKeywordArg():
       unused_proto = unittest_pb2.TestEmptyMessage(unknown='unknown')
-    self._CheckRaises(ValueError,
-                      InitalizeEmptyMessageWithExtraKeywordArg,
-                      'Protocol message has no "unknown" field.')
+    self._CheckRaises(
+        ValueError,
+        InitalizeEmptyMessageWithExtraKeywordArg,
+        'Protocol message TestEmptyMessage has no "unknown" field.')
 
   def testInitRequiredKwargs(self):
     proto = unittest_pb2.TestRequired(a=1, b=1, c=1)
diff --git a/python/google/protobuf/internal/text_format_test.py b/python/google/protobuf/internal/text_format_test.py
index cca0ee63..0e14556c 100755
--- a/python/google/protobuf/internal/text_format_test.py
+++ b/python/google/protobuf/internal/text_format_test.py
@@ -51,8 +51,22 @@ from google.protobuf import unittest_pb2
 from google.protobuf import unittest_proto3_arena_pb2
 from google.protobuf.internal import api_implementation
 from google.protobuf.internal import test_util
+from google.protobuf.internal import message_set_extensions_pb2
 from google.protobuf import text_format
 
+
+# Low-level nuts-n-bolts tests.
+class SimpleTextFormatTests(unittest.TestCase):
+
+  # The members of _QUOTES are formatted into a regexp template that
+  # expects single characters.  Therefore it's an error (in addition to being
+  # non-sensical in the first place) to try to specify a "quote mark" that is
+  # more than one character.
+  def TestQuoteMarksAreSingleChars(self):
+    for quote in text_format._QUOTES:
+      self.assertEqual(1, len(quote))
+
+
 # Base class with some common functionality.
 class TextFormatBase(unittest.TestCase):
 
@@ -287,6 +301,19 @@ class TextFormatTest(TextFormatBase):
     self.assertEqual(u'one', message.repeated_string[0])
     self.assertEqual(u'two', message.repeated_string[1])
 
+  def testParseRepeatedScalarShortFormat(self, message_module):
+    message = message_module.TestAllTypes()
+    text = ('repeated_int64: [100, 200];\n'
+            'repeated_int64: 300,\n'
+            'repeated_string: ["one", "two"];\n')
+    text_format.Parse(text, message)
+
+    self.assertEqual(100, message.repeated_int64[0])
+    self.assertEqual(200, message.repeated_int64[1])
+    self.assertEqual(300, message.repeated_int64[2])
+    self.assertEqual(u'one', message.repeated_string[0])
+    self.assertEqual(u'two', message.repeated_string[1])
+
   def testParseEmptyText(self, message_module):
     message = message_module.TestAllTypes()
     text = ''
@@ -301,7 +328,7 @@ class TextFormatTest(TextFormatBase):
   def testParseSingleWord(self, message_module):
     message = message_module.TestAllTypes()
     text = 'foo'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         (r'1:1 : Message type "\w+.TestAllTypes" has no field named '
          r'"foo".'),
@@ -310,7 +337,7 @@ class TextFormatTest(TextFormatBase):
   def testParseUnknownField(self, message_module):
     message = message_module.TestAllTypes()
     text = 'unknown_field: 8\n'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         (r'1:1 : Message type "\w+.TestAllTypes" has no field named '
          r'"unknown_field".'),
@@ -319,7 +346,7 @@ class TextFormatTest(TextFormatBase):
   def testParseBadEnumValue(self, message_module):
     message = message_module.TestAllTypes()
     text = 'optional_nested_enum: BARR'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         (r'1:23 : Enum type "\w+.TestAllTypes.NestedEnum" '
          r'has no value named BARR.'),
@@ -327,7 +354,7 @@ class TextFormatTest(TextFormatBase):
 
     message = message_module.TestAllTypes()
     text = 'optional_nested_enum: 100'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         (r'1:23 : Enum type "\w+.TestAllTypes.NestedEnum" '
          r'has no value with number 100.'),
@@ -336,7 +363,7 @@ class TextFormatTest(TextFormatBase):
   def testParseBadIntValue(self, message_module):
     message = message_module.TestAllTypes()
     text = 'optional_int32: bork'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         ('1:17 : Couldn\'t parse integer: bork'),
         text_format.Parse, text, message)
@@ -553,6 +580,15 @@ class Proto2Tests(TextFormatBase):
         '  }\n'
         '}\n')
 
+    message = message_set_extensions_pb2.TestMessageSet()
+    ext = message_set_extensions_pb2.message_set_extension3
+    message.Extensions[ext].text = 'bar'
+    self.CompareToGoldenText(
+        text_format.MessageToString(message),
+        '[google.protobuf.internal.TestMessageSetExtension3] {\n'
+        '  text: \"bar\"\n'
+        '}\n')
+
   def testPrintMessageSetAsOneLine(self):
     message = unittest_mset_pb2.TestMessageSetContainer()
     ext1 = unittest_mset_pb2.TestMessageSetExtension1.message_set_extension
@@ -627,15 +663,125 @@ class Proto2Tests(TextFormatBase):
     text_format.Parse(ascii_text, parsed_message)
     self.assertEqual(message, parsed_message)
 
+  def testParseAllowedUnknownExtension(self):
+    # Skip over unknown extension correctly.
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    text = ('message_set {\n'
+            '  [unknown_extension] {\n'
+            '    i: 23\n'
+            '    [nested_unknown_ext]: {\n'
+            '      i: 23\n'
+            '      test: "test_string"\n'
+            '      floaty_float: -0.315\n'
+            '      num: -inf\n'
+            '      multiline_str: "abc"\n'
+            '          "def"\n'
+            '          "xyz."\n'
+            '      [nested_unknown_ext]: <\n'
+            '        i: 23\n'
+            '        i: 24\n'
+            '        pointfloat: .3\n'
+            '        test: "test_string"\n'
+            '        floaty_float: -0.315\n'
+            '        num: -inf\n'
+            '        long_string: "test" "test2" \n'
+            '      >\n'
+            '    }\n'
+            '  }\n'
+            '  [unknown_extension]: 5\n'
+            '}\n')
+    text_format.Parse(text, message, allow_unknown_extension=True)
+    golden = 'message_set {\n}\n'
+    self.CompareToGoldenText(text_format.MessageToString(message), golden)
+
+    # Catch parse errors in unknown extension.
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    malformed = ('message_set {\n'
+                 '  [unknown_extension] {\n'
+                 '    i:\n'  # Missing value.
+                 '  }\n'
+                 '}\n')
+    six.assertRaisesRegex(self,
+                          text_format.ParseError,
+                          'Invalid field value: }',
+                          text_format.Parse, malformed, message,
+                          allow_unknown_extension=True)
+
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    malformed = ('message_set {\n'
+                 '  [unknown_extension] {\n'
+                 '    str: "malformed string\n'  # Missing closing quote.
+                 '  }\n'
+                 '}\n')
+    six.assertRaisesRegex(self,
+                          text_format.ParseError,
+                          'Invalid field value: "',
+                          text_format.Parse, malformed, message,
+                          allow_unknown_extension=True)
+
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    malformed = ('message_set {\n'
+                 '  [unknown_extension] {\n'
+                 '    str: "malformed\n multiline\n string\n'
+                 '  }\n'
+                 '}\n')
+    six.assertRaisesRegex(self,
+                          text_format.ParseError,
+                          'Invalid field value: "',
+                          text_format.Parse, malformed, message,
+                          allow_unknown_extension=True)
+
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    malformed = ('message_set {\n'
+                 '  [malformed_extension] <\n'
+                 '    i: -5\n'
+                 '  \n'  # Missing '>' here.
+                 '}\n')
+    six.assertRaisesRegex(self,
+                          text_format.ParseError,
+                          '5:1 : Expected ">".',
+                          text_format.Parse, malformed, message,
+                          allow_unknown_extension=True)
+
+    # Don't allow unknown fields with allow_unknown_extension=True.
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    malformed = ('message_set {\n'
+                 '  unknown_field: true\n'
+                 '  \n'  # Missing '>' here.
+                 '}\n')
+    six.assertRaisesRegex(self,
+                          text_format.ParseError,
+                          ('2:3 : Message type '
+                           '"proto2_wireformat_unittest.TestMessageSet" has no'
+                           ' field named "unknown_field".'),
+                          text_format.Parse, malformed, message,
+                          allow_unknown_extension=True)
+
+    # Parse known extension correcty.
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    text = ('message_set {\n'
+            '  [protobuf_unittest.TestMessageSetExtension1] {\n'
+            '    i: 23\n'
+            '  }\n'
+            '  [protobuf_unittest.TestMessageSetExtension2] {\n'
+            '    str: \"foo\"\n'
+            '  }\n'
+            '}\n')
+    text_format.Parse(text, message, allow_unknown_extension=True)
+    ext1 = unittest_mset_pb2.TestMessageSetExtension1.message_set_extension
+    ext2 = unittest_mset_pb2.TestMessageSetExtension2.message_set_extension
+    self.assertEqual(23, message.message_set.Extensions[ext1].i)
+    self.assertEqual('foo', message.message_set.Extensions[ext2].str)
+
   def testParseBadExtension(self):
     message = unittest_pb2.TestAllExtensions()
     text = '[unknown_extension]: 8\n'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         '1:2 : Extension "unknown_extension" not registered.',
         text_format.Parse, text, message)
     message = unittest_pb2.TestAllTypes()
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         ('1:2 : Message type "protobuf_unittest.TestAllTypes" does not have '
          'extensions.'),
@@ -654,7 +800,7 @@ class Proto2Tests(TextFormatBase):
     message = unittest_pb2.TestAllExtensions()
     text = ('[protobuf_unittest.optional_int32_extension]: 42 '
             '[protobuf_unittest.optional_int32_extension]: 67')
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         ('1:96 : Message type "protobuf_unittest.TestAllExtensions" '
          'should not have multiple '
@@ -665,7 +811,7 @@ class Proto2Tests(TextFormatBase):
     message = unittest_pb2.TestAllTypes()
     text = ('optional_nested_message { bb: 1 } '
             'optional_nested_message { bb: 2 }')
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         ('1:65 : Message type "protobuf_unittest.TestAllTypes.NestedMessage" '
          'should not have multiple "bb" fields.'),
@@ -675,7 +821,7 @@ class Proto2Tests(TextFormatBase):
     message = unittest_pb2.TestAllTypes()
     text = ('optional_int32: 42 '
             'optional_int32: 67')
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError,
         ('1:36 : Message type "protobuf_unittest.TestAllTypes" should not '
          'have multiple "optional_int32" fields.'),
@@ -684,11 +830,11 @@ class Proto2Tests(TextFormatBase):
   def testParseGroupNotClosed(self):
     message = unittest_pb2.TestAllTypes()
     text = 'RepeatedGroup: <'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError, '1:16 : Expected ">".',
         text_format.Parse, text, message)
     text = 'RepeatedGroup: {'
-    six.assertRaisesRegex(self, 
+    six.assertRaisesRegex(self,
         text_format.ParseError, '1:16 : Expected "}".',
         text_format.Parse, text, message)
 
diff --git a/python/google/protobuf/internal/well_known_types.py b/python/google/protobuf/internal/well_known_types.py
new file mode 100644
index 00000000..d3de9831
--- /dev/null
+++ b/python/google/protobuf/internal/well_known_types.py
@@ -0,0 +1,622 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Contains well known classes.
+
+This files defines well known classes which need extra maintenance including:
+  - Any
+  - Duration
+  - FieldMask
+  - Timestamp
+"""
+
+__author__ = 'jieluo@google.com (Jie Luo)'
+
+from datetime import datetime
+from datetime import timedelta
+
+from google.protobuf.descriptor import FieldDescriptor
+
+_TIMESTAMPFOMAT = '%Y-%m-%dT%H:%M:%S'
+_NANOS_PER_SECOND = 1000000000
+_NANOS_PER_MILLISECOND = 1000000
+_NANOS_PER_MICROSECOND = 1000
+_MILLIS_PER_SECOND = 1000
+_MICROS_PER_SECOND = 1000000
+_SECONDS_PER_DAY = 24 * 3600
+
+
+class Error(Exception):
+  """Top-level module error."""
+
+
+class ParseError(Error):
+  """Thrown in case of parsing error."""
+
+
+class Any(object):
+  """Class for Any Message type."""
+
+  def Pack(self, msg):
+    """Packs the specified message into current Any message."""
+    self.type_url = 'type.googleapis.com/%s' % msg.DESCRIPTOR.full_name
+    self.value = msg.SerializeToString()
+
+  def Unpack(self, msg):
+    """Unpacks the current Any message into specified message."""
+    descriptor = msg.DESCRIPTOR
+    if not self.Is(descriptor):
+      return False
+    msg.ParseFromString(self.value)
+    return True
+
+  def Is(self, descriptor):
+    """Checks if this Any represents the given protobuf type."""
+    # Only last part is to be used: b/25630112
+    return self.type_url.split('/')[-1] == descriptor.full_name
+
+
+class Timestamp(object):
+  """Class for Timestamp message type."""
+
+  def ToJsonString(self):
+    """Converts Timestamp to RFC 3339 date string format.
+
+    Returns:
+      A string converted from timestamp. The string is always Z-normalized
+      and uses 3, 6 or 9 fractional digits as required to represent the
+      exact time. Example of the return format: '1972-01-01T10:00:20.021Z'
+    """
+    nanos = self.nanos % _NANOS_PER_SECOND
+    total_sec = self.seconds + (self.nanos - nanos) // _NANOS_PER_SECOND
+    seconds = total_sec % _SECONDS_PER_DAY
+    days = (total_sec - seconds) // _SECONDS_PER_DAY
+    dt = datetime(1970, 1, 1) + timedelta(days, seconds)
+
+    result = dt.isoformat()
+    if (nanos % 1e9) == 0:
+      # If there are 0 fractional digits, the fractional
+      # point '.' should be omitted when serializing.
+      return result + 'Z'
+    if (nanos % 1e6) == 0:
+      # Serialize 3 fractional digits.
+      return result + '.%03dZ' % (nanos / 1e6)
+    if (nanos % 1e3) == 0:
+      # Serialize 6 fractional digits.
+      return result + '.%06dZ' % (nanos / 1e3)
+    # Serialize 9 fractional digits.
+    return result + '.%09dZ' % nanos
+
+  def FromJsonString(self, value):
+    """Parse a RFC 3339 date string format to Timestamp.
+
+    Args:
+      value: A date string. Any fractional digits (or none) and any offset are
+          accepted as long as they fit into nano-seconds precision.
+          Example of accepted format: '1972-01-01T10:00:20.021-05:00'
+
+    Raises:
+      ParseError: On parsing problems.
+    """
+    timezone_offset = value.find('Z')
+    if timezone_offset == -1:
+      timezone_offset = value.find('+')
+    if timezone_offset == -1:
+      timezone_offset = value.rfind('-')
+    if timezone_offset == -1:
+      raise ParseError(
+          'Failed to parse timestamp: missing valid timezone offset.')
+    time_value = value[0:timezone_offset]
+    # Parse datetime and nanos.
+    point_position = time_value.find('.')
+    if point_position == -1:
+      second_value = time_value
+      nano_value = ''
+    else:
+      second_value = time_value[:point_position]
+      nano_value = time_value[point_position + 1:]
+    date_object = datetime.strptime(second_value, _TIMESTAMPFOMAT)
+    td = date_object - datetime(1970, 1, 1)
+    seconds = td.seconds + td.days * _SECONDS_PER_DAY
+    if len(nano_value) > 9:
+      raise ParseError(
+          'Failed to parse Timestamp: nanos {0} more than '
+          '9 fractional digits.'.format(nano_value))
+    if nano_value:
+      nanos = round(float('0.' + nano_value) * 1e9)
+    else:
+      nanos = 0
+    # Parse timezone offsets.
+    if value[timezone_offset] == 'Z':
+      if len(value) != timezone_offset + 1:
+        raise ParseError('Failed to parse timestamp: invalid trailing'
+                         ' data {0}.'.format(value))
+    else:
+      timezone = value[timezone_offset:]
+      pos = timezone.find(':')
+      if pos == -1:
+        raise ParseError(
+            'Invalid timezone offset value: {0}.'.format(timezone))
+      if timezone[0] == '+':
+        seconds -= (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
+      else:
+        seconds += (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
+    # Set seconds and nanos
+    self.seconds = int(seconds)
+    self.nanos = int(nanos)
+
+  def GetCurrentTime(self):
+    """Get the current UTC into Timestamp."""
+    self.FromDatetime(datetime.utcnow())
+
+  def ToNanoseconds(self):
+    """Converts Timestamp to nanoseconds since epoch."""
+    return self.seconds * _NANOS_PER_SECOND + self.nanos
+
+  def ToMicroseconds(self):
+    """Converts Timestamp to microseconds since epoch."""
+    return (self.seconds * _MICROS_PER_SECOND +
+            self.nanos // _NANOS_PER_MICROSECOND)
+
+  def ToMilliseconds(self):
+    """Converts Timestamp to milliseconds since epoch."""
+    return (self.seconds * _MILLIS_PER_SECOND +
+            self.nanos // _NANOS_PER_MILLISECOND)
+
+  def ToSeconds(self):
+    """Converts Timestamp to seconds since epoch."""
+    return self.seconds
+
+  def FromNanoseconds(self, nanos):
+    """Converts nanoseconds since epoch to Timestamp."""
+    self.seconds = nanos // _NANOS_PER_SECOND
+    self.nanos = nanos % _NANOS_PER_SECOND
+
+  def FromMicroseconds(self, micros):
+    """Converts microseconds since epoch to Timestamp."""
+    self.seconds = micros // _MICROS_PER_SECOND
+    self.nanos = (micros % _MICROS_PER_SECOND) * _NANOS_PER_MICROSECOND
+
+  def FromMilliseconds(self, millis):
+    """Converts milliseconds since epoch to Timestamp."""
+    self.seconds = millis // _MILLIS_PER_SECOND
+    self.nanos = (millis % _MILLIS_PER_SECOND) * _NANOS_PER_MILLISECOND
+
+  def FromSeconds(self, seconds):
+    """Converts seconds since epoch to Timestamp."""
+    self.seconds = seconds
+    self.nanos = 0
+
+  def ToDatetime(self):
+    """Converts Timestamp to datetime."""
+    return datetime.utcfromtimestamp(
+        self.seconds + self.nanos / float(_NANOS_PER_SECOND))
+
+  def FromDatetime(self, dt):
+    """Converts datetime to Timestamp."""
+    td = dt - datetime(1970, 1, 1)
+    self.seconds = td.seconds + td.days * _SECONDS_PER_DAY
+    self.nanos = td.microseconds * _NANOS_PER_MICROSECOND
+
+
+class Duration(object):
+  """Class for Duration message type."""
+
+  def ToJsonString(self):
+    """Converts Duration to string format.
+
+    Returns:
+      A string converted from self. The string format will contains
+      3, 6, or 9 fractional digits depending on the precision required to
+      represent the exact Duration value. For example: "1s", "1.010s",
+      "1.000000100s", "-3.100s"
+    """
+    if self.seconds < 0 or self.nanos < 0:
+      result = '-'
+      seconds = - self.seconds + int((0 - self.nanos) // 1e9)
+      nanos = (0 - self.nanos) % 1e9
+    else:
+      result = ''
+      seconds = self.seconds + int(self.nanos // 1e9)
+      nanos = self.nanos % 1e9
+    result += '%d' % seconds
+    if (nanos % 1e9) == 0:
+      # If there are 0 fractional digits, the fractional
+      # point '.' should be omitted when serializing.
+      return result + 's'
+    if (nanos % 1e6) == 0:
+      # Serialize 3 fractional digits.
+      return result + '.%03ds' % (nanos / 1e6)
+    if (nanos % 1e3) == 0:
+      # Serialize 6 fractional digits.
+      return result + '.%06ds' % (nanos / 1e3)
+    # Serialize 9 fractional digits.
+    return result + '.%09ds' % nanos
+
+  def FromJsonString(self, value):
+    """Converts a string to Duration.
+
+    Args:
+      value: A string to be converted. The string must end with 's'. Any
+          fractional digits (or none) are accepted as long as they fit into
+          precision. For example: "1s", "1.01s", "1.0000001s", "-3.100s
+
+    Raises:
+      ParseError: On parsing problems.
+    """
+    if len(value) < 1 or value[-1] != 's':
+      raise ParseError(
+          'Duration must end with letter "s": {0}.'.format(value))
+    try:
+      pos = value.find('.')
+      if pos == -1:
+        self.seconds = int(value[:-1])
+        self.nanos = 0
+      else:
+        self.seconds = int(value[:pos])
+        if value[0] == '-':
+          self.nanos = int(round(float('-0{0}'.format(value[pos: -1])) *1e9))
+        else:
+          self.nanos = int(round(float('0{0}'.format(value[pos: -1])) *1e9))
+    except ValueError:
+      raise ParseError(
+          'Couldn\'t parse duration: {0}.'.format(value))
+
+  def ToNanoseconds(self):
+    """Converts a Duration to nanoseconds."""
+    return self.seconds * _NANOS_PER_SECOND + self.nanos
+
+  def ToMicroseconds(self):
+    """Converts a Duration to microseconds."""
+    micros = _RoundTowardZero(self.nanos, _NANOS_PER_MICROSECOND)
+    return self.seconds * _MICROS_PER_SECOND + micros
+
+  def ToMilliseconds(self):
+    """Converts a Duration to milliseconds."""
+    millis = _RoundTowardZero(self.nanos, _NANOS_PER_MILLISECOND)
+    return self.seconds * _MILLIS_PER_SECOND + millis
+
+  def ToSeconds(self):
+    """Converts a Duration to seconds."""
+    return self.seconds
+
+  def FromNanoseconds(self, nanos):
+    """Converts nanoseconds to Duration."""
+    self._NormalizeDuration(nanos // _NANOS_PER_SECOND,
+                            nanos % _NANOS_PER_SECOND)
+
+  def FromMicroseconds(self, micros):
+    """Converts microseconds to Duration."""
+    self._NormalizeDuration(
+        micros // _MICROS_PER_SECOND,
+        (micros % _MICROS_PER_SECOND) * _NANOS_PER_MICROSECOND)
+
+  def FromMilliseconds(self, millis):
+    """Converts milliseconds to Duration."""
+    self._NormalizeDuration(
+        millis // _MILLIS_PER_SECOND,
+        (millis % _MILLIS_PER_SECOND) * _NANOS_PER_MILLISECOND)
+
+  def FromSeconds(self, seconds):
+    """Converts seconds to Duration."""
+    self.seconds = seconds
+    self.nanos = 0
+
+  def ToTimedelta(self):
+    """Converts Duration to timedelta."""
+    return timedelta(
+        seconds=self.seconds, microseconds=_RoundTowardZero(
+            self.nanos, _NANOS_PER_MICROSECOND))
+
+  def FromTimedelta(self, td):
+    """Convertd timedelta to Duration."""
+    self._NormalizeDuration(td.seconds + td.days * _SECONDS_PER_DAY,
+                            td.microseconds * _NANOS_PER_MICROSECOND)
+
+  def _NormalizeDuration(self, seconds, nanos):
+    """Set Duration by seconds and nonas."""
+    # Force nanos to be negative if the duration is negative.
+    if seconds < 0 and nanos > 0:
+      seconds += 1
+      nanos -= _NANOS_PER_SECOND
+    self.seconds = seconds
+    self.nanos = nanos
+
+
+def _RoundTowardZero(value, divider):
+  """Truncates the remainder part after division."""
+  # For some languanges, the sign of the remainder is implementation
+  # dependent if any of the operands is negative. Here we enforce
+  # "rounded toward zero" semantics. For example, for (-5) / 2 an
+  # implementation may give -3 as the result with the remainder being
+  # 1. This function ensures we always return -2 (closer to zero).
+  result = value // divider
+  remainder = value % divider
+  if result < 0 and remainder > 0:
+    return result + 1
+  else:
+    return result
+
+
+class FieldMask(object):
+  """Class for FieldMask message type."""
+
+  def ToJsonString(self):
+    """Converts FieldMask to string according to proto3 JSON spec."""
+    return ','.join(self.paths)
+
+  def FromJsonString(self, value):
+    """Converts string to FieldMask according to proto3 JSON spec."""
+    self.Clear()
+    for path in value.split(','):
+      self.paths.append(path)
+
+  def IsValidForDescriptor(self, message_descriptor):
+    """Checks whether the FieldMask is valid for Message Descriptor."""
+    for path in self.paths:
+      if not _IsValidPath(message_descriptor, path):
+        return False
+    return True
+
+  def AllFieldsFromDescriptor(self, message_descriptor):
+    """Gets all direct fields of Message Descriptor to FieldMask."""
+    self.Clear()
+    for field in message_descriptor.fields:
+      self.paths.append(field.name)
+
+  def CanonicalFormFromMask(self, mask):
+    """Converts a FieldMask to the canonical form.
+
+    Removes paths that are covered by another path. For example,
+    "foo.bar" is covered by "foo" and will be removed if "foo"
+    is also in the FieldMask. Then sorts all paths in alphabetical order.
+
+    Args:
+      mask: The original FieldMask to be converted.
+    """
+    tree = _FieldMaskTree(mask)
+    tree.ToFieldMask(self)
+
+  def Union(self, mask1, mask2):
+    """Merges mask1 and mask2 into this FieldMask."""
+    _CheckFieldMaskMessage(mask1)
+    _CheckFieldMaskMessage(mask2)
+    tree = _FieldMaskTree(mask1)
+    tree.MergeFromFieldMask(mask2)
+    tree.ToFieldMask(self)
+
+  def Intersect(self, mask1, mask2):
+    """Intersects mask1 and mask2 into this FieldMask."""
+    _CheckFieldMaskMessage(mask1)
+    _CheckFieldMaskMessage(mask2)
+    tree = _FieldMaskTree(mask1)
+    intersection = _FieldMaskTree()
+    for path in mask2.paths:
+      tree.IntersectPath(path, intersection)
+    intersection.ToFieldMask(self)
+
+  def MergeMessage(
+      self, source, destination,
+      replace_message_field=False, replace_repeated_field=False):
+    """Merges fields specified in FieldMask from source to destination.
+
+    Args:
+      source: Source message.
+      destination: The destination message to be merged into.
+      replace_message_field: Replace message field if True. Merge message
+          field if False.
+      replace_repeated_field: Replace repeated field if True. Append
+          elements of repeated field if False.
+    """
+    tree = _FieldMaskTree(self)
+    tree.MergeMessage(
+        source, destination, replace_message_field, replace_repeated_field)
+
+
+def _IsValidPath(message_descriptor, path):
+  """Checks whether the path is valid for Message Descriptor."""
+  parts = path.split('.')
+  last = parts.pop()
+  for name in parts:
+    field = message_descriptor.fields_by_name[name]
+    if (field is None or
+        field.label == FieldDescriptor.LABEL_REPEATED or
+        field.type != FieldDescriptor.TYPE_MESSAGE):
+      return False
+    message_descriptor = field.message_type
+  return last in message_descriptor.fields_by_name
+
+
+def _CheckFieldMaskMessage(message):
+  """Raises ValueError if message is not a FieldMask."""
+  message_descriptor = message.DESCRIPTOR
+  if (message_descriptor.name != 'FieldMask' or
+      message_descriptor.file.name != 'google/protobuf/field_mask.proto'):
+    raise ValueError('Message {0} is not a FieldMask.'.format(
+        message_descriptor.full_name))
+
+
+class _FieldMaskTree(object):
+  """Represents a FieldMask in a tree structure.
+
+  For example, given a FieldMask "foo.bar,foo.baz,bar.baz",
+  the FieldMaskTree will be:
+      [_root] -+- foo -+- bar
+            |       |
+            |       +- baz
+            |
+            +- bar --- baz
+  In the tree, each leaf node represents a field path.
+  """
+
+  def __init__(self, field_mask=None):
+    """Initializes the tree by FieldMask."""
+    self._root = {}
+    if field_mask:
+      self.MergeFromFieldMask(field_mask)
+
+  def MergeFromFieldMask(self, field_mask):
+    """Merges a FieldMask to the tree."""
+    for path in field_mask.paths:
+      self.AddPath(path)
+
+  def AddPath(self, path):
+    """Adds a field path into the tree.
+
+    If the field path to add is a sub-path of an existing field path
+    in the tree (i.e., a leaf node), it means the tree already matches
+    the given path so nothing will be added to the tree. If the path
+    matches an existing non-leaf node in the tree, that non-leaf node
+    will be turned into a leaf node with all its children removed because
+    the path matches all the node's children. Otherwise, a new path will
+    be added.
+
+    Args:
+      path: The field path to add.
+    """
+    node = self._root
+    for name in path.split('.'):
+      if name not in node:
+        node[name] = {}
+      elif not node[name]:
+        # Pre-existing empty node implies we already have this entire tree.
+        return
+      node = node[name]
+    # Remove any sub-trees we might have had.
+    node.clear()
+
+  def ToFieldMask(self, field_mask):
+    """Converts the tree to a FieldMask."""
+    field_mask.Clear()
+    _AddFieldPaths(self._root, '', field_mask)
+
+  def IntersectPath(self, path, intersection):
+    """Calculates the intersection part of a field path with this tree.
+
+    Args:
+      path: The field path to calculates.
+      intersection: The out tree to record the intersection part.
+    """
+    node = self._root
+    for name in path.split('.'):
+      if name not in node:
+        return
+      elif not node[name]:
+        intersection.AddPath(path)
+        return
+      node = node[name]
+    intersection.AddLeafNodes(path, node)
+
+  def AddLeafNodes(self, prefix, node):
+    """Adds leaf nodes begin with prefix to this tree."""
+    if not node:
+      self.AddPath(prefix)
+    for name in node:
+      child_path = prefix + '.' + name
+      self.AddLeafNodes(child_path, node[name])
+
+  def MergeMessage(
+      self, source, destination,
+      replace_message, replace_repeated):
+    """Merge all fields specified by this tree from source to destination."""
+    _MergeMessage(
+        self._root, source, destination, replace_message, replace_repeated)
+
+
+def _StrConvert(value):
+  """Converts value to str if it is not."""
+  # This file is imported by c extension and some methods like ClearField
+  # requires string for the field name. py2/py3 has different text
+  # type and may use unicode.
+  if not isinstance(value, str):
+    return value.encode('utf-8')
+  return value
+
+
+def _MergeMessage(
+    node, source, destination, replace_message, replace_repeated):
+  """Merge all fields specified by a sub-tree from source to destination."""
+  source_descriptor = source.DESCRIPTOR
+  for name in node:
+    child = node[name]
+    field = source_descriptor.fields_by_name[name]
+    if field is None:
+      raise ValueError('Error: Can\'t find field {0} in message {1}.'.format(
+          name, source_descriptor.full_name))
+    if child:
+      # Sub-paths are only allowed for singular message fields.
+      if (field.label == FieldDescriptor.LABEL_REPEATED or
+          field.cpp_type != FieldDescriptor.CPPTYPE_MESSAGE):
+        raise ValueError('Error: Field {0} in message {1} is not a singular '
+                         'message field and cannot have sub-fields.'.format(
+                             name, source_descriptor.full_name))
+      _MergeMessage(
+          child, getattr(source, name), getattr(destination, name),
+          replace_message, replace_repeated)
+      continue
+    if field.label == FieldDescriptor.LABEL_REPEATED:
+      if replace_repeated:
+        destination.ClearField(_StrConvert(name))
+      repeated_source = getattr(source, name)
+      repeated_destination = getattr(destination, name)
+      if field.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
+        for item in repeated_source:
+          repeated_destination.add().MergeFrom(item)
+      else:
+        repeated_destination.extend(repeated_source)
+    else:
+      if field.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
+        if replace_message:
+          destination.ClearField(_StrConvert(name))
+        if source.HasField(name):
+          getattr(destination, name).MergeFrom(getattr(source, name))
+      else:
+        setattr(destination, name, getattr(source, name))
+
+
+def _AddFieldPaths(node, prefix, field_mask):
+  """Adds the field paths descended from node to field_mask."""
+  if not node:
+    field_mask.paths.append(prefix)
+    return
+  for name in sorted(node):
+    if prefix:
+      child_path = prefix + '.' + name
+    else:
+      child_path = name
+    _AddFieldPaths(node[name], child_path, field_mask)
+
+
+WKTBASES = {
+    'google.protobuf.Any': Any,
+    'google.protobuf.Duration': Duration,
+    'google.protobuf.FieldMask': FieldMask,
+    'google.protobuf.Timestamp': Timestamp,
+}
diff --git a/python/google/protobuf/internal/well_known_types_test.py b/python/google/protobuf/internal/well_known_types_test.py
new file mode 100644
index 00000000..60b0c47d
--- /dev/null
+++ b/python/google/protobuf/internal/well_known_types_test.py
@@ -0,0 +1,509 @@
+#! /usr/bin/env python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Test for google.protobuf.internal.well_known_types."""
+
+__author__ = 'jieluo@google.com (Jie Luo)'
+
+from datetime import datetime
+
+from google.protobuf import duration_pb2
+from google.protobuf import field_mask_pb2
+from google.protobuf import timestamp_pb2
+import unittest
+from google.protobuf import unittest_pb2
+from google.protobuf.internal import test_util
+from google.protobuf.internal import well_known_types
+from google.protobuf import descriptor
+
+
+class TimeUtilTestBase(unittest.TestCase):
+
+  def CheckTimestampConversion(self, message, text):
+    self.assertEqual(text, message.ToJsonString())
+    parsed_message = timestamp_pb2.Timestamp()
+    parsed_message.FromJsonString(text)
+    self.assertEqual(message, parsed_message)
+
+  def CheckDurationConversion(self, message, text):
+    self.assertEqual(text, message.ToJsonString())
+    parsed_message = duration_pb2.Duration()
+    parsed_message.FromJsonString(text)
+    self.assertEqual(message, parsed_message)
+
+
+class TimeUtilTest(TimeUtilTestBase):
+
+  def testTimestampSerializeAndParse(self):
+    message = timestamp_pb2.Timestamp()
+    # Generated output should contain 3, 6, or 9 fractional digits.
+    message.seconds = 0
+    message.nanos = 0
+    self.CheckTimestampConversion(message, '1970-01-01T00:00:00Z')
+    message.nanos = 10000000
+    self.CheckTimestampConversion(message, '1970-01-01T00:00:00.010Z')
+    message.nanos = 10000
+    self.CheckTimestampConversion(message, '1970-01-01T00:00:00.000010Z')
+    message.nanos = 10
+    self.CheckTimestampConversion(message, '1970-01-01T00:00:00.000000010Z')
+    # Test min timestamps.
+    message.seconds = -62135596800
+    message.nanos = 0
+    self.CheckTimestampConversion(message, '0001-01-01T00:00:00Z')
+    # Test max timestamps.
+    message.seconds = 253402300799
+    message.nanos = 999999999
+    self.CheckTimestampConversion(message, '9999-12-31T23:59:59.999999999Z')
+    # Test negative timestamps.
+    message.seconds = -1
+    self.CheckTimestampConversion(message, '1969-12-31T23:59:59.999999999Z')
+
+    # Parsing accepts an fractional digits as long as they fit into nano
+    # precision.
+    message.FromJsonString('1970-01-01T00:00:00.1Z')
+    self.assertEqual(0, message.seconds)
+    self.assertEqual(100000000, message.nanos)
+    # Parsing accpets offsets.
+    message.FromJsonString('1970-01-01T00:00:00-08:00')
+    self.assertEqual(8 * 3600, message.seconds)
+    self.assertEqual(0, message.nanos)
+
+  def testDurationSerializeAndParse(self):
+    message = duration_pb2.Duration()
+    # Generated output should contain 3, 6, or 9 fractional digits.
+    message.seconds = 0
+    message.nanos = 0
+    self.CheckDurationConversion(message, '0s')
+    message.nanos = 10000000
+    self.CheckDurationConversion(message, '0.010s')
+    message.nanos = 10000
+    self.CheckDurationConversion(message, '0.000010s')
+    message.nanos = 10
+    self.CheckDurationConversion(message, '0.000000010s')
+
+    # Test min and max
+    message.seconds = 315576000000
+    message.nanos = 999999999
+    self.CheckDurationConversion(message, '315576000000.999999999s')
+    message.seconds = -315576000000
+    message.nanos = -999999999
+    self.CheckDurationConversion(message, '-315576000000.999999999s')
+
+    # Parsing accepts an fractional digits as long as they fit into nano
+    # precision.
+    message.FromJsonString('0.1s')
+    self.assertEqual(100000000, message.nanos)
+    message.FromJsonString('0.0000001s')
+    self.assertEqual(100, message.nanos)
+
+  def testTimestampIntegerConversion(self):
+    message = timestamp_pb2.Timestamp()
+    message.FromNanoseconds(1)
+    self.assertEqual('1970-01-01T00:00:00.000000001Z',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToNanoseconds())
+
+    message.FromNanoseconds(-1)
+    self.assertEqual('1969-12-31T23:59:59.999999999Z',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToNanoseconds())
+
+    message.FromMicroseconds(1)
+    self.assertEqual('1970-01-01T00:00:00.000001Z',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToMicroseconds())
+
+    message.FromMicroseconds(-1)
+    self.assertEqual('1969-12-31T23:59:59.999999Z',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToMicroseconds())
+
+    message.FromMilliseconds(1)
+    self.assertEqual('1970-01-01T00:00:00.001Z',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToMilliseconds())
+
+    message.FromMilliseconds(-1)
+    self.assertEqual('1969-12-31T23:59:59.999Z',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToMilliseconds())
+
+    message.FromSeconds(1)
+    self.assertEqual('1970-01-01T00:00:01Z',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToSeconds())
+
+    message.FromSeconds(-1)
+    self.assertEqual('1969-12-31T23:59:59Z',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToSeconds())
+
+    message.FromNanoseconds(1999)
+    self.assertEqual(1, message.ToMicroseconds())
+    # For negative values, Timestamp will be rounded down.
+    # For example, "1969-12-31T23:59:59.5Z" (i.e., -0.5s) rounded to seconds
+    # will be "1969-12-31T23:59:59Z" (i.e., -1s) rather than
+    # "1970-01-01T00:00:00Z" (i.e., 0s).
+    message.FromNanoseconds(-1999)
+    self.assertEqual(-2, message.ToMicroseconds())
+
+  def testDurationIntegerConversion(self):
+    message = duration_pb2.Duration()
+    message.FromNanoseconds(1)
+    self.assertEqual('0.000000001s',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToNanoseconds())
+
+    message.FromNanoseconds(-1)
+    self.assertEqual('-0.000000001s',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToNanoseconds())
+
+    message.FromMicroseconds(1)
+    self.assertEqual('0.000001s',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToMicroseconds())
+
+    message.FromMicroseconds(-1)
+    self.assertEqual('-0.000001s',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToMicroseconds())
+
+    message.FromMilliseconds(1)
+    self.assertEqual('0.001s',
+                     message.ToJsonString())
+    self.assertEqual(1, message.ToMilliseconds())
+
+    message.FromMilliseconds(-1)
+    self.assertEqual('-0.001s',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToMilliseconds())
+
+    message.FromSeconds(1)
+    self.assertEqual('1s', message.ToJsonString())
+    self.assertEqual(1, message.ToSeconds())
+
+    message.FromSeconds(-1)
+    self.assertEqual('-1s',
+                     message.ToJsonString())
+    self.assertEqual(-1, message.ToSeconds())
+
+    # Test truncation behavior.
+    message.FromNanoseconds(1999)
+    self.assertEqual(1, message.ToMicroseconds())
+
+    # For negative values, Duration will be rounded towards 0.
+    message.FromNanoseconds(-1999)
+    self.assertEqual(-1, message.ToMicroseconds())
+
+  def testDatetimeConverison(self):
+    message = timestamp_pb2.Timestamp()
+    dt = datetime(1970, 1, 1)
+    message.FromDatetime(dt)
+    self.assertEqual(dt, message.ToDatetime())
+
+    message.FromMilliseconds(1999)
+    self.assertEqual(datetime(1970, 1, 1, 0, 0, 1, 999000),
+                     message.ToDatetime())
+
+  def testTimedeltaConversion(self):
+    message = duration_pb2.Duration()
+    message.FromNanoseconds(1999999999)
+    td = message.ToTimedelta()
+    self.assertEqual(1, td.seconds)
+    self.assertEqual(999999, td.microseconds)
+
+    message.FromNanoseconds(-1999999999)
+    td = message.ToTimedelta()
+    self.assertEqual(-1, td.days)
+    self.assertEqual(86398, td.seconds)
+    self.assertEqual(1, td.microseconds)
+
+    message.FromMicroseconds(-1)
+    td = message.ToTimedelta()
+    self.assertEqual(-1, td.days)
+    self.assertEqual(86399, td.seconds)
+    self.assertEqual(999999, td.microseconds)
+    converted_message = duration_pb2.Duration()
+    converted_message.FromTimedelta(td)
+    self.assertEqual(message, converted_message)
+
+  def testInvalidTimestamp(self):
+    message = timestamp_pb2.Timestamp()
+    self.assertRaisesRegexp(
+        ValueError,
+        'time data \'10000-01-01T00:00:00\' does not match'
+        ' format \'%Y-%m-%dT%H:%M:%S\'',
+        message.FromJsonString, '10000-01-01T00:00:00.00Z')
+    self.assertRaisesRegexp(
+        well_known_types.ParseError,
+        'nanos 0123456789012 more than 9 fractional digits.',
+        message.FromJsonString,
+        '1970-01-01T00:00:00.0123456789012Z')
+    self.assertRaisesRegexp(
+        well_known_types.ParseError,
+        (r'Invalid timezone offset value: \+08.'),
+        message.FromJsonString,
+        '1972-01-01T01:00:00.01+08',)
+    self.assertRaisesRegexp(
+        ValueError,
+        'year is out of range',
+        message.FromJsonString,
+        '0000-01-01T00:00:00Z')
+    message.seconds = 253402300800
+    self.assertRaisesRegexp(
+        OverflowError,
+        'date value out of range',
+        message.ToJsonString)
+
+  def testInvalidDuration(self):
+    message = duration_pb2.Duration()
+    self.assertRaisesRegexp(
+        well_known_types.ParseError,
+        'Duration must end with letter "s": 1.',
+        message.FromJsonString, '1')
+    self.assertRaisesRegexp(
+        well_known_types.ParseError,
+        'Couldn\'t parse duration: 1...2s.',
+        message.FromJsonString, '1...2s')
+
+
+class FieldMaskTest(unittest.TestCase):
+
+  def testStringFormat(self):
+    mask = field_mask_pb2.FieldMask()
+    self.assertEqual('', mask.ToJsonString())
+    mask.paths.append('foo')
+    self.assertEqual('foo', mask.ToJsonString())
+    mask.paths.append('bar')
+    self.assertEqual('foo,bar', mask.ToJsonString())
+
+    mask.FromJsonString('')
+    self.assertEqual('', mask.ToJsonString())
+    mask.FromJsonString('foo')
+    self.assertEqual(['foo'], mask.paths)
+    mask.FromJsonString('foo,bar')
+    self.assertEqual(['foo', 'bar'], mask.paths)
+
+  def testDescriptorToFieldMask(self):
+    mask = field_mask_pb2.FieldMask()
+    msg_descriptor = unittest_pb2.TestAllTypes.DESCRIPTOR
+    mask.AllFieldsFromDescriptor(msg_descriptor)
+    self.assertEqual(75, len(mask.paths))
+    self.assertTrue(mask.IsValidForDescriptor(msg_descriptor))
+    for field in msg_descriptor.fields:
+      self.assertTrue(field.name in mask.paths)
+    mask.paths.append('optional_nested_message.bb')
+    self.assertTrue(mask.IsValidForDescriptor(msg_descriptor))
+    mask.paths.append('repeated_nested_message.bb')
+    self.assertFalse(mask.IsValidForDescriptor(msg_descriptor))
+
+  def testCanonicalFrom(self):
+    mask = field_mask_pb2.FieldMask()
+    out_mask = field_mask_pb2.FieldMask()
+    # Paths will be sorted.
+    mask.FromJsonString('baz.quz,bar,foo')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('bar,baz.quz,foo', out_mask.ToJsonString())
+    # Duplicated paths will be removed.
+    mask.FromJsonString('foo,bar,foo')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('bar,foo', out_mask.ToJsonString())
+    # Sub-paths of other paths will be removed.
+    mask.FromJsonString('foo.b1,bar.b1,foo.b2,bar')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('bar,foo.b1,foo.b2', out_mask.ToJsonString())
+
+    # Test more deeply nested cases.
+    mask.FromJsonString(
+        'foo.bar.baz1,foo.bar.baz2.quz,foo.bar.baz2')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('foo.bar.baz1,foo.bar.baz2',
+                     out_mask.ToJsonString())
+    mask.FromJsonString(
+        'foo.bar.baz1,foo.bar.baz2,foo.bar.baz2.quz')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('foo.bar.baz1,foo.bar.baz2',
+                     out_mask.ToJsonString())
+    mask.FromJsonString(
+        'foo.bar.baz1,foo.bar.baz2,foo.bar.baz2.quz,foo.bar')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('foo.bar', out_mask.ToJsonString())
+    mask.FromJsonString(
+        'foo.bar.baz1,foo.bar.baz2,foo.bar.baz2.quz,foo')
+    out_mask.CanonicalFormFromMask(mask)
+    self.assertEqual('foo', out_mask.ToJsonString())
+
+  def testUnion(self):
+    mask1 = field_mask_pb2.FieldMask()
+    mask2 = field_mask_pb2.FieldMask()
+    out_mask = field_mask_pb2.FieldMask()
+    mask1.FromJsonString('foo,baz')
+    mask2.FromJsonString('bar,quz')
+    out_mask.Union(mask1, mask2)
+    self.assertEqual('bar,baz,foo,quz', out_mask.ToJsonString())
+    # Overlap with duplicated paths.
+    mask1.FromJsonString('foo,baz.bb')
+    mask2.FromJsonString('baz.bb,quz')
+    out_mask.Union(mask1, mask2)
+    self.assertEqual('baz.bb,foo,quz', out_mask.ToJsonString())
+    # Overlap with paths covering some other paths.
+    mask1.FromJsonString('foo.bar.baz,quz')
+    mask2.FromJsonString('foo.bar,bar')
+    out_mask.Union(mask1, mask2)
+    self.assertEqual('bar,foo.bar,quz', out_mask.ToJsonString())
+
+  def testIntersect(self):
+    mask1 = field_mask_pb2.FieldMask()
+    mask2 = field_mask_pb2.FieldMask()
+    out_mask = field_mask_pb2.FieldMask()
+    # Test cases without overlapping.
+    mask1.FromJsonString('foo,baz')
+    mask2.FromJsonString('bar,quz')
+    out_mask.Intersect(mask1, mask2)
+    self.assertEqual('', out_mask.ToJsonString())
+    # Overlap with duplicated paths.
+    mask1.FromJsonString('foo,baz.bb')
+    mask2.FromJsonString('baz.bb,quz')
+    out_mask.Intersect(mask1, mask2)
+    self.assertEqual('baz.bb', out_mask.ToJsonString())
+    # Overlap with paths covering some other paths.
+    mask1.FromJsonString('foo.bar.baz,quz')
+    mask2.FromJsonString('foo.bar,bar')
+    out_mask.Intersect(mask1, mask2)
+    self.assertEqual('foo.bar.baz', out_mask.ToJsonString())
+    mask1.FromJsonString('foo.bar,bar')
+    mask2.FromJsonString('foo.bar.baz,quz')
+    out_mask.Intersect(mask1, mask2)
+    self.assertEqual('foo.bar.baz', out_mask.ToJsonString())
+
+  def testMergeMessage(self):
+    # Test merge one field.
+    src = unittest_pb2.TestAllTypes()
+    test_util.SetAllFields(src)
+    for field in src.DESCRIPTOR.fields:
+      if field.containing_oneof:
+        continue
+      field_name = field.name
+      dst = unittest_pb2.TestAllTypes()
+      # Only set one path to mask.
+      mask = field_mask_pb2.FieldMask()
+      mask.paths.append(field_name)
+      mask.MergeMessage(src, dst)
+      # The expected result message.
+      msg = unittest_pb2.TestAllTypes()
+      if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+        repeated_src = getattr(src, field_name)
+        repeated_msg = getattr(msg, field_name)
+        if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+          for item in repeated_src:
+            repeated_msg.add().CopyFrom(item)
+        else:
+          repeated_msg.extend(repeated_src)
+      elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+        getattr(msg, field_name).CopyFrom(getattr(src, field_name))
+      else:
+        setattr(msg, field_name, getattr(src, field_name))
+      # Only field specified in mask is merged.
+      self.assertEqual(msg, dst)
+
+    # Test merge nested fields.
+    nested_src = unittest_pb2.NestedTestAllTypes()
+    nested_dst = unittest_pb2.NestedTestAllTypes()
+    nested_src.child.payload.optional_int32 = 1234
+    nested_src.child.child.payload.optional_int32 = 5678
+    mask = field_mask_pb2.FieldMask()
+    mask.FromJsonString('child.payload')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(1234, nested_dst.child.payload.optional_int32)
+    self.assertEqual(0, nested_dst.child.child.payload.optional_int32)
+
+    mask.FromJsonString('child.child.payload')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(1234, nested_dst.child.payload.optional_int32)
+    self.assertEqual(5678, nested_dst.child.child.payload.optional_int32)
+
+    nested_dst.Clear()
+    mask.FromJsonString('child.child.payload')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(0, nested_dst.child.payload.optional_int32)
+    self.assertEqual(5678, nested_dst.child.child.payload.optional_int32)
+
+    nested_dst.Clear()
+    mask.FromJsonString('child')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(1234, nested_dst.child.payload.optional_int32)
+    self.assertEqual(5678, nested_dst.child.child.payload.optional_int32)
+
+    # Test MergeOptions.
+    nested_dst.Clear()
+    nested_dst.child.payload.optional_int64 = 4321
+    # Message fields will be merged by default.
+    mask.FromJsonString('child.payload')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(1234, nested_dst.child.payload.optional_int32)
+    self.assertEqual(4321, nested_dst.child.payload.optional_int64)
+    # Change the behavior to replace message fields.
+    mask.FromJsonString('child.payload')
+    mask.MergeMessage(nested_src, nested_dst, True, False)
+    self.assertEqual(1234, nested_dst.child.payload.optional_int32)
+    self.assertEqual(0, nested_dst.child.payload.optional_int64)
+
+    # By default, fields missing in source are not cleared in destination.
+    nested_dst.payload.optional_int32 = 1234
+    self.assertTrue(nested_dst.HasField('payload'))
+    mask.FromJsonString('payload')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertTrue(nested_dst.HasField('payload'))
+    # But they are cleared when replacing message fields.
+    nested_dst.Clear()
+    nested_dst.payload.optional_int32 = 1234
+    mask.FromJsonString('payload')
+    mask.MergeMessage(nested_src, nested_dst, True, False)
+    self.assertFalse(nested_dst.HasField('payload'))
+
+    nested_src.payload.repeated_int32.append(1234)
+    nested_dst.payload.repeated_int32.append(5678)
+    # Repeated fields will be appended by default.
+    mask.FromJsonString('payload.repeated_int32')
+    mask.MergeMessage(nested_src, nested_dst)
+    self.assertEqual(2, len(nested_dst.payload.repeated_int32))
+    self.assertEqual(5678, nested_dst.payload.repeated_int32[0])
+    self.assertEqual(1234, nested_dst.payload.repeated_int32[1])
+    # Change the behavior to replace repeated fields.
+    mask.FromJsonString('payload.repeated_int32')
+    mask.MergeMessage(nested_src, nested_dst, False, True)
+    self.assertEqual(1, len(nested_dst.payload.repeated_int32))
+    self.assertEqual(1234, nested_dst.payload.repeated_int32[0])
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index d95557d7..cb76e116 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -28,22 +28,29 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-"""Contains routines for printing protocol messages in JSON format."""
+"""Contains routines for printing protocol messages in JSON format.
+
+Simple usage example:
+
+  # Create a proto object and serialize it to a json format string.
+  message = my_proto_pb2.MyMessage(foo='bar')
+  json_string = json_format.MessageToJson(message)
+
+  # Parse a json format string to proto object.
+  message = json_format.Parse(json_string, my_proto_pb2.MyMessage())
+"""
 
 __author__ = 'jieluo@google.com (Jie Luo)'
 
 import base64
-from datetime import datetime
 import json
 import math
-import re
+from six import text_type
 import sys
 
 from google.protobuf import descriptor
 
 _TIMESTAMPFOMAT = '%Y-%m-%dT%H:%M:%S'
-_NUMBER = re.compile(u'[0-9+-][0-9e.+-]*')
-_INTEGER = re.compile(u'[0-9+-]')
 _INT_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_INT32,
                         descriptor.FieldDescriptor.CPPTYPE_UINT32,
                         descriptor.FieldDescriptor.CPPTYPE_INT64,
@@ -52,17 +59,20 @@ _INT64_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_INT64,
                           descriptor.FieldDescriptor.CPPTYPE_UINT64])
 _FLOAT_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_FLOAT,
                           descriptor.FieldDescriptor.CPPTYPE_DOUBLE])
-if str is bytes:
-  _UNICODETYPE = unicode
-else:
-  _UNICODETYPE = str
+_INFINITY = 'Infinity'
+_NEG_INFINITY = '-Infinity'
+_NAN = 'NaN'
+
 
+class Error(Exception):
+  """Top-level module error for json_format."""
 
-class SerializeToJsonError(Exception):
+
+class SerializeToJsonError(Error):
   """Thrown if serialization to JSON fails."""
 
 
-class ParseError(Exception):
+class ParseError(Error):
   """Thrown in case of parsing error."""
 
 
@@ -86,12 +96,8 @@ def MessageToJson(message, including_default_value_fields=False):
 def _MessageToJsonObject(message, including_default_value_fields):
   """Converts message to an object according to Proto3 JSON Specification."""
   message_descriptor = message.DESCRIPTOR
-  if _IsTimestampMessage(message_descriptor):
-    return _TimestampMessageToJsonObject(message)
-  if _IsDurationMessage(message_descriptor):
-    return _DurationMessageToJsonObject(message)
-  if _IsFieldMaskMessage(message_descriptor):
-    return _FieldMaskMessageToJsonObject(message)
+  if hasattr(message, 'ToJsonString'):
+    return message.ToJsonString()
   if _IsWrapperMessage(message_descriptor):
     return _WrapperMessageToJsonObject(message)
   return _RegularMessageToJsonObject(message, including_default_value_fields)
@@ -107,12 +113,14 @@ def _RegularMessageToJsonObject(message, including_default_value_fields):
   """Converts normal message according to Proto3 JSON Specification."""
   js = {}
   fields = message.ListFields()
+  include_default = including_default_value_fields
 
   try:
     for field, value in fields:
       name = field.camelcase_name
       if _IsMapEntry(field):
         # Convert a map field.
+        v_field = field.message_type.fields_by_name['value']
         js_map = {}
         for key in value:
           if isinstance(key, bool):
@@ -122,20 +130,15 @@ def _RegularMessageToJsonObject(message, including_default_value_fields):
               recorded_key = 'false'
           else:
             recorded_key = key
-          js_map[recorded_key] = _ConvertFieldToJsonObject(
-              field.message_type.fields_by_name['value'],
-              value[key], including_default_value_fields)
+          js_map[recorded_key] = _FieldToJsonObject(
+              v_field, value[key], including_default_value_fields)
         js[name] = js_map
       elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
         # Convert a repeated field.
-        repeated = []
-        for element in value:
-          repeated.append(_ConvertFieldToJsonObject(
-              field, element, including_default_value_fields))
-        js[name] = repeated
+        js[name] = [_FieldToJsonObject(field, k, include_default)
+                    for k in value]
       else:
-        js[name] = _ConvertFieldToJsonObject(
-            field, value, including_default_value_fields)
+        js[name] = _FieldToJsonObject(field, value, include_default)
 
     # Serialize default value if including_default_value_fields is True.
     if including_default_value_fields:
@@ -155,16 +158,16 @@ def _RegularMessageToJsonObject(message, including_default_value_fields):
         elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
           js[name] = []
         else:
-          js[name] = _ConvertFieldToJsonObject(field, field.default_value)
+          js[name] = _FieldToJsonObject(field, field.default_value)
 
   except ValueError as e:
     raise SerializeToJsonError(
-        'Failed to serialize {0} field: {1}'.format(field.name, e))
+        'Failed to serialize {0} field: {1}.'.format(field.name, e))
 
   return js
 
 
-def _ConvertFieldToJsonObject(
+def _FieldToJsonObject(
     field, value, including_default_value_fields=False):
   """Converts field value according to Proto3 JSON Specification."""
   if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
@@ -183,101 +186,26 @@ def _ConvertFieldToJsonObject(
     else:
       return value
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
-    if value:
-      return True
-    else:
-      return False
+    return bool(value)
   elif field.cpp_type in _INT64_TYPES:
     return str(value)
   elif field.cpp_type in _FLOAT_TYPES:
     if math.isinf(value):
       if value < 0.0:
-        return '-Infinity'
+        return _NEG_INFINITY
       else:
-        return 'Infinity'
+        return _INFINITY
     if math.isnan(value):
-      return 'NaN'
+      return _NAN
   return value
 
 
-def _IsTimestampMessage(message_descriptor):
-  return (message_descriptor.name == 'Timestamp' and
-          message_descriptor.file.name == 'google/protobuf/timestamp.proto')
-
-
-def _TimestampMessageToJsonObject(message):
-  """Converts Timestamp message according to Proto3 JSON Specification."""
-  nanos = message.nanos % 1e9
-  dt = datetime.utcfromtimestamp(
-      message.seconds + (message.nanos - nanos) / 1e9)
-  result = dt.isoformat()
-  if (nanos % 1e9) == 0:
-    # If there are 0 fractional digits, the fractional
-    # point '.' should be omitted when serializing.
-    return result + 'Z'
-  if (nanos % 1e6) == 0:
-    # Serialize 3 fractional digits.
-    return result + '.%03dZ' % (nanos / 1e6)
-  if (nanos % 1e3) == 0:
-    # Serialize 6 fractional digits.
-    return result + '.%06dZ' % (nanos / 1e3)
-  # Serialize 9 fractional digits.
-  return result + '.%09dZ' % nanos
-
-
-def _IsDurationMessage(message_descriptor):
-  return (message_descriptor.name == 'Duration' and
-          message_descriptor.file.name == 'google/protobuf/duration.proto')
-
-
-def _DurationMessageToJsonObject(message):
-  """Converts Duration message according to Proto3 JSON Specification."""
-  if message.seconds < 0 or message.nanos < 0:
-    result = '-'
-    seconds = - message.seconds + int((0 - message.nanos) / 1e9)
-    nanos = (0 - message.nanos) % 1e9
-  else:
-    result = ''
-    seconds = message.seconds + int(message.nanos / 1e9)
-    nanos = message.nanos % 1e9
-  result += '%d' % seconds
-  if (nanos % 1e9) == 0:
-    # If there are 0 fractional digits, the fractional
-    # point '.' should be omitted when serializing.
-    return result + 's'
-  if (nanos % 1e6) == 0:
-    # Serialize 3 fractional digits.
-    return result + '.%03ds' % (nanos / 1e6)
-  if (nanos % 1e3) == 0:
-    # Serialize 6 fractional digits.
-    return result + '.%06ds' % (nanos / 1e3)
-    # Serialize 9 fractional digits.
-  return result + '.%09ds' % nanos
-
-
-def _IsFieldMaskMessage(message_descriptor):
-  return (message_descriptor.name == 'FieldMask' and
-          message_descriptor.file.name == 'google/protobuf/field_mask.proto')
-
-
-def _FieldMaskMessageToJsonObject(message):
-  """Converts FieldMask message according to Proto3 JSON Specification."""
-  result = ''
-  first = True
-  for path in message.paths:
-    if not first:
-      result += ','
-    result += path
-    first = False
-  return result
-
-
 def _IsWrapperMessage(message_descriptor):
   return message_descriptor.file.name == 'google/protobuf/wrappers.proto'
 
 
 def _WrapperMessageToJsonObject(message):
-  return _ConvertFieldToJsonObject(
+  return _FieldToJsonObject(
       message.DESCRIPTOR.fields_by_name['value'], message.value)
 
 
@@ -285,7 +213,7 @@ def _DuplicateChecker(js):
   result = {}
   for name, value in js:
     if name in result:
-      raise ParseError('Failed to load JSON: duplicate key ' + name)
+      raise ParseError('Failed to load JSON: duplicate key {0}.'.format(name))
     result[name] = value
   return result
 
@@ -303,7 +231,7 @@ def Parse(text, message):
   Raises::
     ParseError: On JSON parsing problems.
   """
-  if not isinstance(text, _UNICODETYPE): text = text.decode('utf-8')
+  if not isinstance(text, text_type): text = text.decode('utf-8')
   try:
     if sys.version_info < (2, 7):
       # object_pair_hook is not supported before python2.7
@@ -311,7 +239,7 @@ def Parse(text, message):
     else:
       js = json.loads(text, object_pairs_hook=_DuplicateChecker)
   except ValueError as e:
-    raise ParseError('Failed to load JSON: ' + str(e))
+    raise ParseError('Failed to load JSON: {0}.'.format(str(e)))
   _ConvertFieldValuePair(js, message)
   return message
 
@@ -362,7 +290,7 @@ def _ConvertFieldValuePair(js, message):
         message.ClearField(field.name)
         if not isinstance(value, list):
           raise ParseError('repeated field {0} must be in [] which is '
-                           '{1}'.format(name, value))
+                           '{1}.'.format(name, value))
         for item in value:
           if item is None:
             continue
@@ -383,9 +311,9 @@ def _ConvertFieldValuePair(js, message):
       else:
         raise ParseError(str(e))
     except ValueError as e:
-      raise ParseError('Failed to parse {0} field: {1}'.format(name, e))
+      raise ParseError('Failed to parse {0} field: {1}.'.format(name, e))
     except TypeError as e:
-      raise ParseError('Failed to parse {0} field: {1}'.format(name, e))
+      raise ParseError('Failed to parse {0} field: {1}.'.format(name, e))
 
 
 def _ConvertMessage(value, message):
@@ -399,88 +327,13 @@ def _ConvertMessage(value, message):
     ParseError: In case of convert problems.
   """
   message_descriptor = message.DESCRIPTOR
-  if _IsTimestampMessage(message_descriptor):
-    _ConvertTimestampMessage(value, message)
-  elif _IsDurationMessage(message_descriptor):
-    _ConvertDurationMessage(value, message)
-  elif _IsFieldMaskMessage(message_descriptor):
-    _ConvertFieldMaskMessage(value, message)
+  if hasattr(message, 'FromJsonString'):
+    message.FromJsonString(value)
   elif _IsWrapperMessage(message_descriptor):
     _ConvertWrapperMessage(value, message)
   else:
     _ConvertFieldValuePair(value, message)
 
-
-def _ConvertTimestampMessage(value, message):
-  """Convert a JSON representation into Timestamp message."""
-  timezone_offset = value.find('Z')
-  if timezone_offset == -1:
-    timezone_offset = value.find('+')
-  if timezone_offset == -1:
-    timezone_offset = value.rfind('-')
-  if timezone_offset == -1:
-    raise ParseError(
-        'Failed to parse timestamp: missing valid timezone offset.')
-  time_value = value[0:timezone_offset]
-  # Parse datetime and nanos
-  point_position = time_value.find('.')
-  if point_position == -1:
-    second_value = time_value
-    nano_value = ''
-  else:
-    second_value = time_value[:point_position]
-    nano_value = time_value[point_position + 1:]
-  date_object = datetime.strptime(second_value, _TIMESTAMPFOMAT)
-  td = date_object - datetime(1970, 1, 1)
-  seconds = td.seconds + td.days * 24 * 3600
-  if len(nano_value) > 9:
-    raise ParseError(
-        'Failed to parse Timestamp: nanos {0} more than '
-        '9 fractional digits.'.format(nano_value))
-  if nano_value:
-    nanos = round(float('0.' + nano_value) * 1e9)
-  else:
-    nanos = 0
-  # Parse timezone offsets
-  if value[timezone_offset] == 'Z':
-    if len(value) != timezone_offset + 1:
-      raise ParseError(
-          'Failed to parse timestamp: invalid trailing data {0}.'.format(value))
-  else:
-    timezone = value[timezone_offset:]
-    pos = timezone.find(':')
-    if pos == -1:
-      raise ParseError(
-          'Invalid timezone offset value: ' + timezone)
-    if timezone[0] == '+':
-      seconds += (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
-    else:
-      seconds -= (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
-  # Set seconds and nanos
-  message.seconds = int(seconds)
-  message.nanos = int(nanos)
-
-
-def _ConvertDurationMessage(value, message):
-  """Convert a JSON representation into Duration message."""
-  if value[-1] != 's':
-    raise ParseError(
-        'Duration must end with letter "s": ' + value)
-  try:
-    duration = float(value[:-1])
-  except ValueError:
-    raise ParseError(
-        'Couldn\'t parse duration: ' + value)
-  message.seconds = int(duration)
-  message.nanos = int(round((duration - message.seconds) * 1e9))
-
-
-def _ConvertFieldMaskMessage(value, message):
-  """Convert a JSON representation into FieldMask message."""
-  for path in value.split(','):
-    message.paths.append(path)
-
-
 def _ConvertWrapperMessage(value, message):
   """Convert a JSON representation into Wrapper message."""
   field = message.DESCRIPTOR.fields_by_name['value']
@@ -512,13 +365,13 @@ def _ConvertMapFieldValue(value, message, field):
           value[key], value_field)
 
 
-def _ConvertScalarFieldValue(value, field, require_quote=False):
+def _ConvertScalarFieldValue(value, field, require_str=False):
   """Convert a single scalar field value.
 
   Args:
     value: A scalar value to convert the scalar field value.
     field: The descriptor of the field to convert.
-    require_quote: If True, '"' is required for the field value.
+    require_str: If True, the field value must be a str.
 
   Returns:
     The converted scalar field value
@@ -531,7 +384,7 @@ def _ConvertScalarFieldValue(value, field, require_quote=False):
   elif field.cpp_type in _FLOAT_TYPES:
     return _ConvertFloat(value)
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
-    return _ConvertBool(value, require_quote)
+    return _ConvertBool(value, require_str)
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
     if field.type == descriptor.FieldDescriptor.TYPE_BYTES:
       return base64.b64decode(value)
@@ -561,10 +414,10 @@ def _ConvertInteger(value):
     ParseError: If an integer couldn't be consumed.
   """
   if isinstance(value, float):
-    raise ParseError('Couldn\'t parse integer: {0}'.format(value))
+    raise ParseError('Couldn\'t parse integer: {0}.'.format(value))
 
-  if isinstance(value, _UNICODETYPE) and not _INTEGER.match(value):
-    raise ParseError('Couldn\'t parse integer: "{0}"'.format(value))
+  if isinstance(value, text_type) and value.find(' ') != -1:
+    raise ParseError('Couldn\'t parse integer: "{0}".'.format(value))
 
   return int(value)
 
@@ -572,28 +425,28 @@ def _ConvertInteger(value):
 def _ConvertFloat(value):
   """Convert an floating point number."""
   if value == 'nan':
-    raise ParseError('Couldn\'t parse float "nan", use "NaN" instead')
+    raise ParseError('Couldn\'t parse float "nan", use "NaN" instead.')
   try:
     # Assume Python compatible syntax.
     return float(value)
   except ValueError:
     # Check alternative spellings.
-    if value == '-Infinity':
+    if value == _NEG_INFINITY:
       return float('-inf')
-    elif value == 'Infinity':
+    elif value == _INFINITY:
       return float('inf')
-    elif value == 'NaN':
+    elif value == _NAN:
       return float('nan')
     else:
-      raise ParseError('Couldn\'t parse float: {0}'.format(value))
+      raise ParseError('Couldn\'t parse float: {0}.'.format(value))
 
 
-def _ConvertBool(value, require_quote):
+def _ConvertBool(value, require_str):
   """Convert a boolean value.
 
   Args:
     value: A scalar value to convert.
-    require_quote: If True, '"' is required for the boolean value.
+    require_str: If True, value must be a str.
 
   Returns:
     The bool parsed.
@@ -601,13 +454,13 @@ def _ConvertBool(value, require_quote):
   Raises:
     ParseError: If a boolean value couldn't be consumed.
   """
-  if require_quote:
+  if require_str:
     if value == 'true':
       return True
     elif value == 'false':
       return False
     else:
-      raise ParseError('Expect "true" or "false", not {0}.'.format(value))
+      raise ParseError('Expected "true" or "false", not {0}.'.format(value))
 
   if not isinstance(value, bool):
     raise ParseError('Expected true or false without quotes.')
diff --git a/python/google/protobuf/message_factory.py b/python/google/protobuf/message_factory.py
index 9cd9c2a8..1b059d13 100644
--- a/python/google/protobuf/message_factory.py
+++ b/python/google/protobuf/message_factory.py
@@ -39,7 +39,6 @@ my_proto_instance = message_classes['some.proto.package.MessageName']()
 
 __author__ = 'matthewtoia@google.com (Matt Toia)'
 
-from google.protobuf import descriptor_database
 from google.protobuf import descriptor_pool
 from google.protobuf import message
 from google.protobuf import reflection
@@ -50,8 +49,7 @@ class MessageFactory(object):
 
   def __init__(self, pool=None):
     """Initializes a new factory."""
-    self.pool = (pool or descriptor_pool.DescriptorPool(
-        descriptor_database.DescriptorDatabase()))
+    self.pool = pool or descriptor_pool.DescriptorPool()
 
     # local cache of all classes built from protobuf descriptors
     self._classes = {}
diff --git a/python/google/protobuf/pyext/descriptor.cc b/python/google/protobuf/pyext/descriptor.cc
index 61a3d237..a875a7be 100644
--- a/python/google/protobuf/pyext/descriptor.cc
+++ b/python/google/protobuf/pyext/descriptor.cc
@@ -203,6 +203,14 @@ static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
   PyObject* message_class(cdescriptor_pool::GetMessageClass(
       pool, message_type));
   if (message_class == NULL) {
+    // The Options message was not found in the current DescriptorPool.
+    // In this case, there cannot be extensions to these options, and we can
+    // try to use the basic pool instead.
+    PyErr_Clear();
+    message_class = cdescriptor_pool::GetMessageClass(
+      GetDefaultDescriptorPool(), message_type);
+  }
+  if (message_class == NULL) {
     PyErr_Format(PyExc_TypeError, "Could not retrieve class for Options: %s",
                  message_type->full_name().c_str());
     return NULL;
@@ -211,6 +219,12 @@ static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
   if (value == NULL) {
     return NULL;
   }
+  if (!PyObject_TypeCheck(value.get(), &CMessage_Type)) {
+      PyErr_Format(PyExc_TypeError, "Invalid class for %s: %s",
+                   message_type->full_name().c_str(),
+                   Py_TYPE(value.get())->tp_name);
+      return NULL;
+  }
   CMessage* cmsg = reinterpret_cast<CMessage*>(value.get());
 
   const Reflection* reflection = options.GetReflection();
@@ -327,7 +341,8 @@ PyObject* NewInternedDescriptor(PyTypeObject* type,
   PyDescriptorPool* pool = GetDescriptorPool_FromPool(
       GetFileDescriptor(descriptor)->pool());
   if (pool == NULL) {
-    Py_DECREF(py_descriptor);
+    // Don't DECREF, the object is not fully initialized.
+    PyObject_Del(py_descriptor);
     return NULL;
   }
   Py_INCREF(pool);
@@ -1213,6 +1228,13 @@ static void Dealloc(PyFileDescriptor* self) {
   descriptor::Dealloc(&self->base);
 }
 
+static PyObject* GetPool(PyFileDescriptor *self, void *closure) {
+  PyObject* pool = reinterpret_cast<PyObject*>(
+      GetDescriptorPool_FromPool(_GetDescriptor(self)->pool()));
+  Py_XINCREF(pool);
+  return pool;
+}
+
 static PyObject* GetName(PyFileDescriptor *self, void *closure) {
   return PyString_FromCppString(_GetDescriptor(self)->name());
 }
@@ -1292,6 +1314,7 @@ static PyObject* CopyToProto(PyFileDescriptor *self, PyObject *target) {
 }
 
 static PyGetSetDef Getters[] = {
+  { "pool", (getter)GetPool, NULL, "pool"},
   { "name", (getter)GetName, NULL, "name"},
   { "package", (getter)GetPackage, NULL, "package"},
   { "serialized_pb", (getter)GetSerializedPb},
@@ -1354,8 +1377,8 @@ PyTypeObject PyFileDescriptor_Type = {
   0,                                    // tp_descr_set
   0,                                    // tp_dictoffset
   0,                                    // tp_init
-  PyType_GenericAlloc,                  // tp_alloc
-  PyType_GenericNew,                    // tp_new
+  0,                                    // tp_alloc
+  0,                                    // tp_new
   PyObject_Del,                         // tp_free
 };
 
diff --git a/python/google/protobuf/pyext/descriptor_database.cc b/python/google/protobuf/pyext/descriptor_database.cc
new file mode 100644
index 00000000..514722b4
--- /dev/null
+++ b/python/google/protobuf/pyext/descriptor_database.cc
@@ -0,0 +1,145 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// This file defines a C++ DescriptorDatabase, which wraps a Python Database
+// and delegate all its operations to Python methods.
+
+#include <google/protobuf/pyext/descriptor_database.h>
+
+#include <google/protobuf/stubs/logging.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/pyext/message.h>
+#include <google/protobuf/pyext/scoped_pyobject_ptr.h>
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+PyDescriptorDatabase::PyDescriptorDatabase(PyObject* py_database)
+    : py_database_(py_database) {
+  Py_INCREF(py_database_);
+}
+
+PyDescriptorDatabase::~PyDescriptorDatabase() { Py_DECREF(py_database_); }
+
+// Convert a Python object to a FileDescriptorProto pointer.
+// Handles all kinds of Python errors, which are simply logged.
+static bool GetFileDescriptorProto(PyObject* py_descriptor,
+                                   FileDescriptorProto* output) {
+  if (py_descriptor == NULL) {
+    if (PyErr_ExceptionMatches(PyExc_KeyError)) {
+      // Expected error: item was simply not found.
+      PyErr_Clear();
+    } else {
+      GOOGLE_LOG(ERROR) << "DescriptorDatabase method raised an error";
+      PyErr_Print();
+    }
+    return false;
+  }
+  const Descriptor* filedescriptor_descriptor =
+      FileDescriptorProto::default_instance().GetDescriptor();
+  CMessage* message = reinterpret_cast<CMessage*>(py_descriptor);
+  if (PyObject_TypeCheck(py_descriptor, &CMessage_Type) &&
+      message->message->GetDescriptor() == filedescriptor_descriptor) {
+    // Fast path: Just use the pointer.
+    FileDescriptorProto* file_proto =
+        static_cast<FileDescriptorProto*>(message->message);
+    *output = *file_proto;
+    return true;
+  } else {
+    // Slow path: serialize the message. This allows to use databases which
+    // use a different implementation of FileDescriptorProto.
+    ScopedPyObjectPtr serialized_pb(
+        PyObject_CallMethod(py_descriptor, "SerializeToString", NULL));
+    if (serialized_pb == NULL) {
+      GOOGLE_LOG(ERROR)
+          << "DescriptorDatabase method did not return a FileDescriptorProto";
+      PyErr_Print();
+      return false;
+    }
+    char* str;
+    Py_ssize_t len;
+    if (PyBytes_AsStringAndSize(serialized_pb.get(), &str, &len) < 0) {
+      GOOGLE_LOG(ERROR)
+          << "DescriptorDatabase method did not return a FileDescriptorProto";
+      PyErr_Print();
+      return false;
+    }
+    FileDescriptorProto file_proto;
+    if (!file_proto.ParseFromArray(str, len)) {
+      GOOGLE_LOG(ERROR)
+          << "DescriptorDatabase method did not return a FileDescriptorProto";
+      return false;
+    }
+    *output = file_proto;
+    return true;
+  }
+}
+
+// Find a file by file name.
+bool PyDescriptorDatabase::FindFileByName(const string& filename,
+                                          FileDescriptorProto* output) {
+  ScopedPyObjectPtr py_descriptor(PyObject_CallMethod(
+      py_database_, "FindFileByName", "s#", filename.c_str(), filename.size()));
+  return GetFileDescriptorProto(py_descriptor.get(), output);
+}
+
+// Find the file that declares the given fully-qualified symbol name.
+bool PyDescriptorDatabase::FindFileContainingSymbol(
+    const string& symbol_name, FileDescriptorProto* output) {
+  ScopedPyObjectPtr py_descriptor(
+      PyObject_CallMethod(py_database_, "FindFileContainingSymbol", "s#",
+                          symbol_name.c_str(), symbol_name.size()));
+  return GetFileDescriptorProto(py_descriptor.get(), output);
+}
+
+// Find the file which defines an extension extending the given message type
+// with the given field number.
+// Python DescriptorDatabases are not required to implement this method.
+bool PyDescriptorDatabase::FindFileContainingExtension(
+    const string& containing_type, int field_number,
+    FileDescriptorProto* output) {
+  ScopedPyObjectPtr py_method(
+      PyObject_GetAttrString(py_database_, "FindFileContainingExtension"));
+  if (py_method == NULL) {
+    // This method is not implemented, returns without error.
+    PyErr_Clear();
+    return false;
+  }
+  ScopedPyObjectPtr py_descriptor(
+      PyObject_CallFunction(py_method.get(), "s#i", containing_type.c_str(),
+                            containing_type.size(), field_number));
+  return GetFileDescriptorProto(py_descriptor.get(), output);
+}
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google
diff --git a/python/google/protobuf/pyext/descriptor_database.h b/python/google/protobuf/pyext/descriptor_database.h
new file mode 100644
index 00000000..fc71c4bc
--- /dev/null
+++ b/python/google/protobuf/pyext/descriptor_database.h
@@ -0,0 +1,75 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_DESCRIPTOR_DATABASE_H__
+#define GOOGLE_PROTOBUF_PYTHON_CPP_DESCRIPTOR_DATABASE_H__
+
+#include <Python.h>
+
+#include <google/protobuf/descriptor_database.h>
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+class PyDescriptorDatabase : public DescriptorDatabase {
+ public:
+  explicit PyDescriptorDatabase(PyObject* py_database);
+  ~PyDescriptorDatabase();
+
+  // Implement the abstract interface. All these functions fill the output
+  // with a copy of FileDescriptorProto.
+
+  // Find a file by file name.
+  bool FindFileByName(const string& filename,
+                      FileDescriptorProto* output);
+
+  // Find the file that declares the given fully-qualified symbol name.
+  bool FindFileContainingSymbol(const string& symbol_name,
+                                FileDescriptorProto* output);
+
+  // Find the file which defines an extension extending the given message type
+  // with the given field number.
+  // Containing_type must be a fully-qualified type name.
+  // Python objects are not required to implement this method.
+  bool FindFileContainingExtension(const string& containing_type,
+                                   int field_number,
+                                   FileDescriptorProto* output);
+
+ private:
+  // The python object that implements the database. The reference is owned.
+  PyObject* py_database_;
+};
+
+}  // namespace python
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_DESCRIPTOR_DATABASE_H__
diff --git a/python/google/protobuf/pyext/descriptor_pool.cc b/python/google/protobuf/pyext/descriptor_pool.cc
index 0f7487fa..0bc76bc9 100644
--- a/python/google/protobuf/pyext/descriptor_pool.cc
+++ b/python/google/protobuf/pyext/descriptor_pool.cc
@@ -34,8 +34,9 @@
 
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/dynamic_message.h>
-#include <google/protobuf/pyext/descriptor_pool.h>
 #include <google/protobuf/pyext/descriptor.h>
+#include <google/protobuf/pyext/descriptor_database.h>
+#include <google/protobuf/pyext/descriptor_pool.h>
 #include <google/protobuf/pyext/message.h>
 #include <google/protobuf/pyext/scoped_pyobject_ptr.h>
 
@@ -60,38 +61,93 @@ static hash_map<const DescriptorPool*, PyDescriptorPool*> descriptor_pool_map;
 
 namespace cdescriptor_pool {
 
-static PyDescriptorPool* NewDescriptorPool() {
-  PyDescriptorPool* cdescriptor_pool = PyObject_New(
+// Create a Python DescriptorPool object, but does not fill the "pool"
+// attribute.
+static PyDescriptorPool* _CreateDescriptorPool() {
+  PyDescriptorPool* cpool = PyObject_New(
       PyDescriptorPool, &PyDescriptorPool_Type);
-  if (cdescriptor_pool == NULL) {
+  if (cpool == NULL) {
     return NULL;
   }
 
-  // Build a DescriptorPool for messages only declared in Python libraries.
-  // generated_pool() contains all messages linked in C++ libraries, and is used
-  // as underlay.
-  cdescriptor_pool->pool = new DescriptorPool(DescriptorPool::generated_pool());
+  cpool->underlay = NULL;
+  cpool->database = NULL;
 
   DynamicMessageFactory* message_factory = new DynamicMessageFactory();
   // This option might be the default some day.
   message_factory->SetDelegateToGeneratedFactory(true);
-  cdescriptor_pool->message_factory = message_factory;
+  cpool->message_factory = message_factory;
 
   // TODO(amauryfa): Rewrite the SymbolDatabase in C so that it uses the same
   // storage.
-  cdescriptor_pool->classes_by_descriptor =
+  cpool->classes_by_descriptor =
       new PyDescriptorPool::ClassesByMessageMap();
-  cdescriptor_pool->descriptor_options =
+  cpool->descriptor_options =
       new hash_map<const void*, PyObject *>();
 
+  return cpool;
+}
+
+// Create a Python DescriptorPool, using the given pool as an underlay:
+// new messages will be added to a custom pool, not to the underlay.
+//
+// Ownership of the underlay is not transferred, its pointer should
+// stay alive.
+static PyDescriptorPool* PyDescriptorPool_NewWithUnderlay(
+    const DescriptorPool* underlay) {
+  PyDescriptorPool* cpool = _CreateDescriptorPool();
+  if (cpool == NULL) {
+    return NULL;
+  }
+  cpool->pool = new DescriptorPool(underlay);
+  cpool->underlay = underlay;
+
   if (!descriptor_pool_map.insert(
-      std::make_pair(cdescriptor_pool->pool, cdescriptor_pool)).second) {
+      std::make_pair(cpool->pool, cpool)).second) {
     // Should never happen -- would indicate an internal error / bug.
     PyErr_SetString(PyExc_ValueError, "DescriptorPool already registered");
     return NULL;
   }
 
-  return cdescriptor_pool;
+  return cpool;
+}
+
+static PyDescriptorPool* PyDescriptorPool_NewWithDatabase(
+    DescriptorDatabase* database) {
+  PyDescriptorPool* cpool = _CreateDescriptorPool();
+  if (cpool == NULL) {
+    return NULL;
+  }
+  if (database != NULL) {
+    cpool->pool = new DescriptorPool(database);
+    cpool->database = database;
+  } else {
+    cpool->pool = new DescriptorPool();
+  }
+
+  if (!descriptor_pool_map.insert(std::make_pair(cpool->pool, cpool)).second) {
+    // Should never happen -- would indicate an internal error / bug.
+    PyErr_SetString(PyExc_ValueError, "DescriptorPool already registered");
+    return NULL;
+  }
+
+  return cpool;
+}
+
+// The public DescriptorPool constructor.
+static PyObject* New(PyTypeObject* type,
+                     PyObject* args, PyObject* kwargs) {
+  static char* kwlist[] = {"descriptor_db", 0};
+  PyObject* py_database = NULL;
+  if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|O", kwlist, &py_database)) {
+    return NULL;
+  }
+  DescriptorDatabase* database = NULL;
+  if (py_database && py_database != Py_None) {
+    database = new PyDescriptorDatabase(py_database);
+  }
+  return reinterpret_cast<PyObject*>(
+      PyDescriptorPool_NewWithDatabase(database));
 }
 
 static void Dealloc(PyDescriptorPool* self) {
@@ -108,8 +164,9 @@ static void Dealloc(PyDescriptorPool* self) {
     Py_DECREF(it->second);
   }
   delete self->descriptor_options;
-  delete self->pool;
   delete self->message_factory;
+  delete self->database;
+  delete self->pool;
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
@@ -354,6 +411,14 @@ PyObject* AddSerializedFile(PyDescriptorPool* self, PyObject* serialized_pb) {
   char* message_type;
   Py_ssize_t message_len;
 
+  if (self->database != NULL) {
+    PyErr_SetString(
+        PyExc_ValueError,
+        "Cannot call Add on a DescriptorPool that uses a DescriptorDatabase. "
+        "Add your file to the underlying database.");
+    return NULL;
+  }
+
   if (PyBytes_AsStringAndSize(serialized_pb, &message_type, &message_len) < 0) {
     return NULL;
   }
@@ -366,8 +431,10 @@ PyObject* AddSerializedFile(PyDescriptorPool* self, PyObject* serialized_pb) {
 
   // If the file was already part of a C++ library, all its descriptors are in
   // the underlying pool.  No need to do anything else.
-  const FileDescriptor* generated_file =
-      DescriptorPool::generated_pool()->FindFileByName(file_proto.name());
+  const FileDescriptor* generated_file = NULL;
+  if (self->underlay) {
+    generated_file = self->underlay->FindFileByName(file_proto.name());
+  }
   if (generated_file != NULL) {
     return PyFileDescriptor_FromDescriptorWithSerializedPb(
         generated_file, serialized_pb);
@@ -470,7 +537,7 @@ PyTypeObject PyDescriptorPool_Type = {
   0,                                   // tp_dictoffset
   0,                                   // tp_init
   0,                                   // tp_alloc
-  0,                                   // tp_new
+  cdescriptor_pool::New,               // tp_new
   PyObject_Del,                        // tp_free
 };
 
@@ -482,7 +549,11 @@ bool InitDescriptorPool() {
   if (PyType_Ready(&PyDescriptorPool_Type) < 0)
     return false;
 
-  python_generated_pool = cdescriptor_pool::NewDescriptorPool();
+  // The Pool of messages declared in Python libraries.
+  // generated_pool() contains all messages already linked in C++ libraries, and
+  // is used as underlay.
+  python_generated_pool = cdescriptor_pool::PyDescriptorPool_NewWithUnderlay(
+      DescriptorPool::generated_pool());
   if (python_generated_pool == NULL) {
     return false;
   }
@@ -494,6 +565,10 @@ bool InitDescriptorPool() {
   return true;
 }
 
+// The default DescriptorPool used everywhere in this module.
+// Today it's the python_generated_pool.
+// TODO(amauryfa): Remove all usages of this function: the pool should be
+// derived from the context.
 PyDescriptorPool* GetDefaultDescriptorPool() {
   return python_generated_pool;
 }
diff --git a/python/google/protobuf/pyext/descriptor_pool.h b/python/google/protobuf/pyext/descriptor_pool.h
index eda73d38..16bc910c 100644
--- a/python/google/protobuf/pyext/descriptor_pool.h
+++ b/python/google/protobuf/pyext/descriptor_pool.h
@@ -55,8 +55,17 @@ namespace python {
 typedef struct PyDescriptorPool {
   PyObject_HEAD
 
+  // The C++ pool containing Descriptors.
   DescriptorPool* pool;
 
+  // The C++ pool acting as an underlay. Can be NULL.
+  // This pointer is not owned and must stay alive.
+  const DescriptorPool* underlay;
+
+  // The C++ descriptor database used to fetch unknown protos. Can be NULL.
+  // This pointer is owned.
+  const DescriptorDatabase* database;
+
   // DynamicMessageFactory used to create C++ instances of messages.
   // This object cache the descriptors that were used, so the DescriptorPool
   // needs to get rid of it before it can delete itself.
@@ -138,6 +147,7 @@ PyObject* FindOneofByName(PyDescriptorPool* self, PyObject* arg);
 // Retrieve the global descriptor pool owned by the _message module.
 // This is the one used by pb2.py generated modules.
 // Returns a *borrowed* reference.
+// "Default" pool used to register messages from _pb2.py modules.
 PyDescriptorPool* GetDefaultDescriptorPool();
 
 // Retrieve the python descriptor pool owning a C++ descriptor pool.
diff --git a/python/google/protobuf/pyext/extension_dict.cc b/python/google/protobuf/pyext/extension_dict.cc
index b361b342..555bd293 100644
--- a/python/google/protobuf/pyext/extension_dict.cc
+++ b/python/google/protobuf/pyext/extension_dict.cc
@@ -94,13 +94,13 @@ PyObject* subscript(ExtensionDict* self, PyObject* key) {
   if (descriptor == NULL) {
     return NULL;
   }
-  if (!CheckFieldBelongsToMessage(descriptor, self->parent->message)) {
+  if (!CheckFieldBelongsToMessage(descriptor, self->message)) {
     return NULL;
   }
 
   if (descriptor->label() != FieldDescriptor::LABEL_REPEATED &&
       descriptor->cpp_type() != FieldDescriptor::CPPTYPE_MESSAGE) {
-    return cmessage::InternalGetScalar(self->parent->message, descriptor);
+    return cmessage::InternalGetScalar(self->message, descriptor);
   }
 
   PyObject* value = PyDict_GetItem(self->values, key);
@@ -109,6 +109,14 @@ PyObject* subscript(ExtensionDict* self, PyObject* key) {
     return value;
   }
 
+  if (self->parent == NULL) {
+    // We are in "detached" state. Don't allow further modifications.
+    // TODO(amauryfa): Support adding non-scalars to a detached extension dict.
+    // This probably requires to store the type of the main message.
+    PyErr_SetObject(PyExc_KeyError, key);
+    return NULL;
+  }
+
   if (descriptor->label() != FieldDescriptor::LABEL_REPEATED &&
       descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
     PyObject* sub_message = cmessage::InternalGetSubMessage(
@@ -154,7 +162,7 @@ int ass_subscript(ExtensionDict* self, PyObject* key, PyObject* value) {
   if (descriptor == NULL) {
     return -1;
   }
-  if (!CheckFieldBelongsToMessage(descriptor, self->parent->message)) {
+  if (!CheckFieldBelongsToMessage(descriptor, self->message)) {
     return -1;
   }
 
@@ -164,9 +172,11 @@ int ass_subscript(ExtensionDict* self, PyObject* key, PyObject* value) {
                     "type");
     return -1;
   }
-  cmessage::AssureWritable(self->parent);
-  if (cmessage::InternalSetScalar(self->parent, descriptor, value) < 0) {
-    return -1;
+  if (self->parent) {
+    cmessage::AssureWritable(self->parent);
+    if (cmessage::InternalSetScalar(self->parent, descriptor, value) < 0) {
+      return -1;
+    }
   }
   // TODO(tibell): We shouldn't write scalars to the cache.
   PyDict_SetItem(self->values, key, value);
@@ -180,15 +190,17 @@ PyObject* ClearExtension(ExtensionDict* self, PyObject* extension) {
     return NULL;
   }
   PyObject* value = PyDict_GetItem(self->values, extension);
-  if (value != NULL) {
-    if (ReleaseExtension(self, value, descriptor) < 0) {
+  if (self->parent) {
+    if (value != NULL) {
+      if (ReleaseExtension(self, value, descriptor) < 0) {
+        return NULL;
+      }
+    }
+    if (ScopedPyObjectPtr(cmessage::ClearFieldByDescriptor(
+            self->parent, descriptor)) == NULL) {
       return NULL;
     }
   }
-  if (ScopedPyObjectPtr(cmessage::ClearFieldByDescriptor(
-          self->parent, descriptor)) == NULL) {
-    return NULL;
-  }
   if (PyDict_DelItem(self->values, extension) < 0) {
     PyErr_Clear();
   }
@@ -201,8 +213,15 @@ PyObject* HasExtension(ExtensionDict* self, PyObject* extension) {
   if (descriptor == NULL) {
     return NULL;
   }
-  PyObject* result = cmessage::HasFieldByDescriptor(self->parent, descriptor);
-  return result;
+  if (self->parent) {
+    return cmessage::HasFieldByDescriptor(self->parent, descriptor);
+  } else {
+    int exists = PyDict_Contains(self->values, extension);
+    if (exists < 0) {
+      return NULL;
+    }
+    return PyBool_FromLong(exists);
+  }
 }
 
 PyObject* _FindExtensionByName(ExtensionDict* self, PyObject* name) {
diff --git a/python/google/protobuf/pyext/extension_dict.h b/python/google/protobuf/pyext/extension_dict.h
index 7a66cb23..d92cf956 100644
--- a/python/google/protobuf/pyext/extension_dict.h
+++ b/python/google/protobuf/pyext/extension_dict.h
@@ -117,11 +117,6 @@ int ass_subscript(ExtensionDict* self, PyObject* key, PyObject* value);
 PyObject* ClearExtension(ExtensionDict* self,
                                        PyObject* extension);
 
-// Checks if the dict has an extension.
-//
-// Returns a new python boolean reference.
-PyObject* HasExtension(ExtensionDict* self, PyObject* extension);
-
 // Gets an extension from the dict given the extension name as opposed to
 // descriptor.
 //
diff --git a/python/google/protobuf/pyext/map_container.cc b/python/google/protobuf/pyext/map_container.cc
new file mode 100644
index 00000000..c39f7b83
--- /dev/null
+++ b/python/google/protobuf/pyext/map_container.cc
@@ -0,0 +1,912 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Author: haberman@google.com (Josh Haberman)
+
+#include <google/protobuf/pyext/map_container.h>
+
+#include <google/protobuf/stubs/logging.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/scoped_ptr.h>
+#include <google/protobuf/map_field.h>
+#include <google/protobuf/map.h>
+#include <google/protobuf/message.h>
+#include <google/protobuf/pyext/message.h>
+#include <google/protobuf/pyext/scoped_pyobject_ptr.h>
+
+#if PY_MAJOR_VERSION >= 3
+  #define PyInt_FromLong PyLong_FromLong
+  #define PyInt_FromSize_t PyLong_FromSize_t
+#endif
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+// Functions that need access to map reflection functionality.
+// They need to be contained in this class because it is friended.
+class MapReflectionFriend {
+ public:
+  // Methods that are in common between the map types.
+  static PyObject* Contains(PyObject* _self, PyObject* key);
+  static Py_ssize_t Length(PyObject* _self);
+  static PyObject* GetIterator(PyObject *_self);
+  static PyObject* IterNext(PyObject* _self);
+
+  // Methods that differ between the map types.
+  static PyObject* ScalarMapGetItem(PyObject* _self, PyObject* key);
+  static PyObject* MessageMapGetItem(PyObject* _self, PyObject* key);
+  static int ScalarMapSetItem(PyObject* _self, PyObject* key, PyObject* v);
+  static int MessageMapSetItem(PyObject* _self, PyObject* key, PyObject* v);
+};
+
+struct MapIterator {
+  PyObject_HEAD;
+
+  scoped_ptr< ::google::protobuf::MapIterator> iter;
+
+  // A pointer back to the container, so we can notice changes to the version.
+  // We own a ref on this.
+  MapContainer* container;
+
+  // We need to keep a ref on the Message* too, because
+  // MapIterator::~MapIterator() accesses it.  Normally this would be ok because
+  // the ref on container (above) would guarantee outlive semantics.  However in
+  // the case of ClearField(), InitializeAndCopyToParentContainer() resets the
+  // message pointer (and the owner) to a different message, a copy of the
+  // original.  But our iterator still points to the original, which could now
+  // get deleted before us.
+  //
+  // To prevent this, we ensure that the Message will always stay alive as long
+  // as this iterator does.  This is solely for the benefit of the MapIterator
+  // destructor -- we should never actually access the iterator in this state
+  // except to delete it.
+  shared_ptr<Message> owner;
+
+  // The version of the map when we took the iterator to it.
+  //
+  // We store this so that if the map is modified during iteration we can throw
+  // an error.
+  uint64 version;
+
+  // True if the container is empty.  We signal this separately to avoid calling
+  // any of the iteration methods, which are non-const.
+  bool empty;
+};
+
+Message* MapContainer::GetMutableMessage() {
+  cmessage::AssureWritable(parent);
+  return const_cast<Message*>(message);
+}
+
+// Consumes a reference on the Python string object.
+static bool PyStringToSTL(PyObject* py_string, string* stl_string) {
+  char *value;
+  Py_ssize_t value_len;
+
+  if (!py_string) {
+    return false;
+  }
+  if (PyBytes_AsStringAndSize(py_string, &value, &value_len) < 0) {
+    Py_DECREF(py_string);
+    return false;
+  } else {
+    stl_string->assign(value, value_len);
+    Py_DECREF(py_string);
+    return true;
+  }
+}
+
+static bool PythonToMapKey(PyObject* obj,
+                           const FieldDescriptor* field_descriptor,
+                           MapKey* key) {
+  switch (field_descriptor->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32: {
+      GOOGLE_CHECK_GET_INT32(obj, value, false);
+      key->SetInt32Value(value);
+      break;
+    }
+    case FieldDescriptor::CPPTYPE_INT64: {
+      GOOGLE_CHECK_GET_INT64(obj, value, false);
+      key->SetInt64Value(value);
+      break;
+    }
+    case FieldDescriptor::CPPTYPE_UINT32: {
+      GOOGLE_CHECK_GET_UINT32(obj, value, false);
+      key->SetUInt32Value(value);
+      break;
+    }
+    case FieldDescriptor::CPPTYPE_UINT64: {
+      GOOGLE_CHECK_GET_UINT64(obj, value, false);
+      key->SetUInt64Value(value);
+      break;
+    }
+    case FieldDescriptor::CPPTYPE_BOOL: {
+      GOOGLE_CHECK_GET_BOOL(obj, value, false);
+      key->SetBoolValue(value);
+      break;
+    }
+    case FieldDescriptor::CPPTYPE_STRING: {
+      string str;
+      if (!PyStringToSTL(CheckString(obj, field_descriptor), &str)) {
+        return false;
+      }
+      key->SetStringValue(str);
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Type %d cannot be a map key",
+          field_descriptor->cpp_type());
+      return false;
+  }
+  return true;
+}
+
+static PyObject* MapKeyToPython(const FieldDescriptor* field_descriptor,
+                                const MapKey& key) {
+  switch (field_descriptor->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+      return PyInt_FromLong(key.GetInt32Value());
+    case FieldDescriptor::CPPTYPE_INT64:
+      return PyLong_FromLongLong(key.GetInt64Value());
+    case FieldDescriptor::CPPTYPE_UINT32:
+      return PyInt_FromSize_t(key.GetUInt32Value());
+    case FieldDescriptor::CPPTYPE_UINT64:
+      return PyLong_FromUnsignedLongLong(key.GetUInt64Value());
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return PyBool_FromLong(key.GetBoolValue());
+    case FieldDescriptor::CPPTYPE_STRING:
+      return ToStringObject(field_descriptor, key.GetStringValue());
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Couldn't convert type %d to value",
+          field_descriptor->cpp_type());
+      return NULL;
+  }
+}
+
+// This is only used for ScalarMap, so we don't need to handle the
+// CPPTYPE_MESSAGE case.
+PyObject* MapValueRefToPython(const FieldDescriptor* field_descriptor,
+                              MapValueRef* value) {
+  switch (field_descriptor->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+      return PyInt_FromLong(value->GetInt32Value());
+    case FieldDescriptor::CPPTYPE_INT64:
+      return PyLong_FromLongLong(value->GetInt64Value());
+    case FieldDescriptor::CPPTYPE_UINT32:
+      return PyInt_FromSize_t(value->GetUInt32Value());
+    case FieldDescriptor::CPPTYPE_UINT64:
+      return PyLong_FromUnsignedLongLong(value->GetUInt64Value());
+    case FieldDescriptor::CPPTYPE_FLOAT:
+      return PyFloat_FromDouble(value->GetFloatValue());
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return PyFloat_FromDouble(value->GetDoubleValue());
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return PyBool_FromLong(value->GetBoolValue());
+    case FieldDescriptor::CPPTYPE_STRING:
+      return ToStringObject(field_descriptor, value->GetStringValue());
+    case FieldDescriptor::CPPTYPE_ENUM:
+      return PyInt_FromLong(value->GetEnumValue());
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Couldn't convert type %d to value",
+          field_descriptor->cpp_type());
+      return NULL;
+  }
+}
+
+// This is only used for ScalarMap, so we don't need to handle the
+// CPPTYPE_MESSAGE case.
+static bool PythonToMapValueRef(PyObject* obj,
+                                const FieldDescriptor* field_descriptor,
+                                bool allow_unknown_enum_values,
+                                MapValueRef* value_ref) {
+  switch (field_descriptor->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32: {
+      GOOGLE_CHECK_GET_INT32(obj, value, false);
+      value_ref->SetInt32Value(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_INT64: {
+      GOOGLE_CHECK_GET_INT64(obj, value, false);
+      value_ref->SetInt64Value(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_UINT32: {
+      GOOGLE_CHECK_GET_UINT32(obj, value, false);
+      value_ref->SetUInt32Value(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_UINT64: {
+      GOOGLE_CHECK_GET_UINT64(obj, value, false);
+      value_ref->SetUInt64Value(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_FLOAT: {
+      GOOGLE_CHECK_GET_FLOAT(obj, value, false);
+      value_ref->SetFloatValue(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_DOUBLE: {
+      GOOGLE_CHECK_GET_DOUBLE(obj, value, false);
+      value_ref->SetDoubleValue(value);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_BOOL: {
+      GOOGLE_CHECK_GET_BOOL(obj, value, false);
+      value_ref->SetBoolValue(value);
+      return true;;
+    }
+    case FieldDescriptor::CPPTYPE_STRING: {
+      string str;
+      if (!PyStringToSTL(CheckString(obj, field_descriptor), &str)) {
+        return false;
+      }
+      value_ref->SetStringValue(str);
+      return true;
+    }
+    case FieldDescriptor::CPPTYPE_ENUM: {
+      GOOGLE_CHECK_GET_INT32(obj, value, false);
+      if (allow_unknown_enum_values) {
+        value_ref->SetEnumValue(value);
+        return true;
+      } else {
+        const EnumDescriptor* enum_descriptor = field_descriptor->enum_type();
+        const EnumValueDescriptor* enum_value =
+            enum_descriptor->FindValueByNumber(value);
+        if (enum_value != NULL) {
+          value_ref->SetEnumValue(value);
+          return true;
+        } else {
+          PyErr_Format(PyExc_ValueError, "Unknown enum value: %d", value);
+          return false;
+        }
+      }
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Setting value to a field of unknown type %d",
+          field_descriptor->cpp_type());
+      return false;
+  }
+}
+
+// Map methods common to ScalarMap and MessageMap //////////////////////////////
+
+static MapContainer* GetMap(PyObject* obj) {
+  return reinterpret_cast<MapContainer*>(obj);
+}
+
+Py_ssize_t MapReflectionFriend::Length(PyObject* _self) {
+  MapContainer* self = GetMap(_self);
+  const google::protobuf::Message* message = self->message;
+  return message->GetReflection()->MapSize(*message,
+                                           self->parent_field_descriptor);
+}
+
+PyObject* Clear(PyObject* _self) {
+  MapContainer* self = GetMap(_self);
+  Message* message = self->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+
+  reflection->ClearField(message, self->parent_field_descriptor);
+
+  Py_RETURN_NONE;
+}
+
+PyObject* MapReflectionFriend::Contains(PyObject* _self, PyObject* key) {
+  MapContainer* self = GetMap(_self);
+
+  const Message* message = self->message;
+  const Reflection* reflection = message->GetReflection();
+  MapKey map_key;
+
+  if (!PythonToMapKey(key, self->key_field_descriptor, &map_key)) {
+    return NULL;
+  }
+
+  if (reflection->ContainsMapKey(*message, self->parent_field_descriptor,
+                                 map_key)) {
+    Py_RETURN_TRUE;
+  } else {
+    Py_RETURN_FALSE;
+  }
+}
+
+// Initializes the underlying Message object of "to" so it becomes a new parent
+// repeated scalar, and copies all the values from "from" to it. A child scalar
+// container can be released by passing it as both from and to (e.g. making it
+// the recipient of the new parent message and copying the values from itself).
+static int InitializeAndCopyToParentContainer(MapContainer* from,
+                                              MapContainer* to) {
+  // For now we require from == to, re-evaluate if we want to support deep copy
+  // as in repeated_scalar_container.cc.
+  GOOGLE_DCHECK(from == to);
+  Message* new_message = from->message->New();
+
+  if (MapReflectionFriend::Length(reinterpret_cast<PyObject*>(from)) > 0) {
+    // A somewhat roundabout way of copying just one field from old_message to
+    // new_message.  This is the best we can do with what Reflection gives us.
+    Message* mutable_old = from->GetMutableMessage();
+    vector<const FieldDescriptor*> fields;
+    fields.push_back(from->parent_field_descriptor);
+
+    // Move the map field into the new message.
+    mutable_old->GetReflection()->SwapFields(mutable_old, new_message, fields);
+
+    // If/when we support from != to, this will be required also to copy the
+    // map field back into the existing message:
+    // mutable_old->MergeFrom(*new_message);
+  }
+
+  // If from == to this could delete old_message.
+  to->owner.reset(new_message);
+
+  to->parent = NULL;
+  to->parent_field_descriptor = from->parent_field_descriptor;
+  to->message = new_message;
+
+  // Invalidate iterators, since they point to the old copy of the field.
+  to->version++;
+
+  return 0;
+}
+
+int MapContainer::Release() {
+  return InitializeAndCopyToParentContainer(this, this);
+}
+
+
+// ScalarMap ///////////////////////////////////////////////////////////////////
+
+PyObject *NewScalarMapContainer(
+    CMessage* parent, const google::protobuf::FieldDescriptor* parent_field_descriptor) {
+  if (!CheckFieldBelongsToMessage(parent_field_descriptor, parent->message)) {
+    return NULL;
+  }
+
+  ScopedPyObjectPtr obj(PyType_GenericAlloc(&ScalarMapContainer_Type, 0));
+  if (obj.get() == NULL) {
+    return PyErr_Format(PyExc_RuntimeError,
+                        "Could not allocate new container.");
+  }
+
+  MapContainer* self = GetMap(obj.get());
+
+  self->message = parent->message;
+  self->parent = parent;
+  self->parent_field_descriptor = parent_field_descriptor;
+  self->owner = parent->owner;
+  self->version = 0;
+
+  self->key_field_descriptor =
+      parent_field_descriptor->message_type()->FindFieldByName("key");
+  self->value_field_descriptor =
+      parent_field_descriptor->message_type()->FindFieldByName("value");
+
+  if (self->key_field_descriptor == NULL ||
+      self->value_field_descriptor == NULL) {
+    return PyErr_Format(PyExc_KeyError,
+                        "Map entry descriptor did not have key/value fields");
+  }
+
+  return obj.release();
+}
+
+PyObject* MapReflectionFriend::ScalarMapGetItem(PyObject* _self,
+                                                PyObject* key) {
+  MapContainer* self = GetMap(_self);
+
+  Message* message = self->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+  MapKey map_key;
+  MapValueRef value;
+
+  if (!PythonToMapKey(key, self->key_field_descriptor, &map_key)) {
+    return NULL;
+  }
+
+  if (reflection->InsertOrLookupMapValue(message, self->parent_field_descriptor,
+                                         map_key, &value)) {
+    self->version++;
+  }
+
+  return MapValueRefToPython(self->value_field_descriptor, &value);
+}
+
+int MapReflectionFriend::ScalarMapSetItem(PyObject* _self, PyObject* key,
+                                          PyObject* v) {
+  MapContainer* self = GetMap(_self);
+
+  Message* message = self->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+  MapKey map_key;
+  MapValueRef value;
+
+  if (!PythonToMapKey(key, self->key_field_descriptor, &map_key)) {
+    return -1;
+  }
+
+  self->version++;
+
+  if (v) {
+    // Set item to v.
+    reflection->InsertOrLookupMapValue(message, self->parent_field_descriptor,
+                                       map_key, &value);
+
+    return PythonToMapValueRef(v, self->value_field_descriptor,
+                               reflection->SupportsUnknownEnumValues(), &value)
+               ? 0
+               : -1;
+  } else {
+    // Delete key from map.
+    if (reflection->DeleteMapValue(message, self->parent_field_descriptor,
+                                   map_key)) {
+      return 0;
+    } else {
+      PyErr_Format(PyExc_KeyError, "Key not present in map");
+      return -1;
+    }
+  }
+}
+
+static PyObject* ScalarMapGet(PyObject* self, PyObject* args) {
+  PyObject* key;
+  PyObject* default_value = NULL;
+  if (PyArg_ParseTuple(args, "O|O", &key, &default_value) < 0) {
+    return NULL;
+  }
+
+  ScopedPyObjectPtr is_present(MapReflectionFriend::Contains(self, key));
+  if (is_present.get() == NULL) {
+    return NULL;
+  }
+
+  if (PyObject_IsTrue(is_present.get())) {
+    return MapReflectionFriend::ScalarMapGetItem(self, key);
+  } else {
+    if (default_value != NULL) {
+      Py_INCREF(default_value);
+      return default_value;
+    } else {
+      Py_RETURN_NONE;
+    }
+  }
+}
+
+static void ScalarMapDealloc(PyObject* _self) {
+  MapContainer* self = GetMap(_self);
+  self->owner.reset();
+  Py_TYPE(_self)->tp_free(_self);
+}
+
+static PyMappingMethods ScalarMapMappingMethods = {
+  MapReflectionFriend::Length,             // mp_length
+  MapReflectionFriend::ScalarMapGetItem,   // mp_subscript
+  MapReflectionFriend::ScalarMapSetItem,   // mp_ass_subscript
+};
+
+static PyMethodDef ScalarMapMethods[] = {
+  { "__contains__", MapReflectionFriend::Contains, METH_O,
+    "Tests whether a key is a member of the map." },
+  { "clear", (PyCFunction)Clear, METH_NOARGS,
+    "Removes all elements from the map." },
+  { "get", ScalarMapGet, METH_VARARGS,
+    "Gets the value for the given key if present, or otherwise a default" },
+  /*
+  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
+    "Makes a deep copy of the class." },
+  { "__reduce__", (PyCFunction)Reduce, METH_NOARGS,
+    "Outputs picklable representation of the repeated field." },
+  */
+  {NULL, NULL},
+};
+
+PyTypeObject ScalarMapContainer_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  FULL_MODULE_NAME ".ScalarMapContainer",  //  tp_name
+  sizeof(MapContainer),                //  tp_basicsize
+  0,                                   //  tp_itemsize
+  ScalarMapDealloc,                    //  tp_dealloc
+  0,                                   //  tp_print
+  0,                                   //  tp_getattr
+  0,                                   //  tp_setattr
+  0,                                   //  tp_compare
+  0,                                   //  tp_repr
+  0,                                   //  tp_as_number
+  0,                                   //  tp_as_sequence
+  &ScalarMapMappingMethods,            //  tp_as_mapping
+  0,                                   //  tp_hash
+  0,                                   //  tp_call
+  0,                                   //  tp_str
+  0,                                   //  tp_getattro
+  0,                                   //  tp_setattro
+  0,                                   //  tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                  //  tp_flags
+  "A scalar map container",            //  tp_doc
+  0,                                   //  tp_traverse
+  0,                                   //  tp_clear
+  0,                                   //  tp_richcompare
+  0,                                   //  tp_weaklistoffset
+  MapReflectionFriend::GetIterator,    //  tp_iter
+  0,                                   //  tp_iternext
+  ScalarMapMethods,                    //  tp_methods
+  0,                                   //  tp_members
+  0,                                   //  tp_getset
+  0,                                   //  tp_base
+  0,                                   //  tp_dict
+  0,                                   //  tp_descr_get
+  0,                                   //  tp_descr_set
+  0,                                   //  tp_dictoffset
+  0,                                   //  tp_init
+};
+
+
+// MessageMap //////////////////////////////////////////////////////////////////
+
+static MessageMapContainer* GetMessageMap(PyObject* obj) {
+  return reinterpret_cast<MessageMapContainer*>(obj);
+}
+
+static PyObject* GetCMessage(MessageMapContainer* self, Message* message) {
+  // Get or create the CMessage object corresponding to this message.
+  ScopedPyObjectPtr key(PyLong_FromVoidPtr(message));
+  PyObject* ret = PyDict_GetItem(self->message_dict, key.get());
+
+  if (ret == NULL) {
+    CMessage* cmsg = cmessage::NewEmptyMessage(self->subclass_init,
+                                               message->GetDescriptor());
+    ret = reinterpret_cast<PyObject*>(cmsg);
+
+    if (cmsg == NULL) {
+      return NULL;
+    }
+    cmsg->owner = self->owner;
+    cmsg->message = message;
+    cmsg->parent = self->parent;
+
+    if (PyDict_SetItem(self->message_dict, key.get(), ret) < 0) {
+      Py_DECREF(ret);
+      return NULL;
+    }
+  } else {
+    Py_INCREF(ret);
+  }
+
+  return ret;
+}
+
+PyObject* NewMessageMapContainer(
+    CMessage* parent, const google::protobuf::FieldDescriptor* parent_field_descriptor,
+    PyObject* concrete_class) {
+  if (!CheckFieldBelongsToMessage(parent_field_descriptor, parent->message)) {
+    return NULL;
+  }
+
+  PyObject* obj = PyType_GenericAlloc(&MessageMapContainer_Type, 0);
+  if (obj == NULL) {
+    return PyErr_Format(PyExc_RuntimeError,
+                        "Could not allocate new container.");
+  }
+
+  MessageMapContainer* self = GetMessageMap(obj);
+
+  self->message = parent->message;
+  self->parent = parent;
+  self->parent_field_descriptor = parent_field_descriptor;
+  self->owner = parent->owner;
+  self->version = 0;
+
+  self->key_field_descriptor =
+      parent_field_descriptor->message_type()->FindFieldByName("key");
+  self->value_field_descriptor =
+      parent_field_descriptor->message_type()->FindFieldByName("value");
+
+  self->message_dict = PyDict_New();
+  if (self->message_dict == NULL) {
+    return PyErr_Format(PyExc_RuntimeError,
+                        "Could not allocate message dict.");
+  }
+
+  Py_INCREF(concrete_class);
+  self->subclass_init = concrete_class;
+
+  if (self->key_field_descriptor == NULL ||
+      self->value_field_descriptor == NULL) {
+    Py_DECREF(obj);
+    return PyErr_Format(PyExc_KeyError,
+                        "Map entry descriptor did not have key/value fields");
+  }
+
+  return obj;
+}
+
+int MapReflectionFriend::MessageMapSetItem(PyObject* _self, PyObject* key,
+                                           PyObject* v) {
+  if (v) {
+    PyErr_Format(PyExc_ValueError,
+                 "Direct assignment of submessage not allowed");
+    return -1;
+  }
+
+  // Now we know that this is a delete, not a set.
+
+  MessageMapContainer* self = GetMessageMap(_self);
+  Message* message = self->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+  MapKey map_key;
+  MapValueRef value;
+
+  self->version++;
+
+  if (!PythonToMapKey(key, self->key_field_descriptor, &map_key)) {
+    return -1;
+  }
+
+  // Delete key from map.
+  if (reflection->DeleteMapValue(message, self->parent_field_descriptor,
+                                 map_key)) {
+    return 0;
+  } else {
+    PyErr_Format(PyExc_KeyError, "Key not present in map");
+    return -1;
+  }
+}
+
+PyObject* MapReflectionFriend::MessageMapGetItem(PyObject* _self,
+                                                 PyObject* key) {
+  MessageMapContainer* self = GetMessageMap(_self);
+
+  Message* message = self->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+  MapKey map_key;
+  MapValueRef value;
+
+  if (!PythonToMapKey(key, self->key_field_descriptor, &map_key)) {
+    return NULL;
+  }
+
+  if (reflection->InsertOrLookupMapValue(message, self->parent_field_descriptor,
+                                         map_key, &value)) {
+    self->version++;
+  }
+
+  return GetCMessage(self, value.MutableMessageValue());
+}
+
+PyObject* MessageMapGet(PyObject* self, PyObject* args) {
+  PyObject* key;
+  PyObject* default_value = NULL;
+  if (PyArg_ParseTuple(args, "O|O", &key, &default_value) < 0) {
+    return NULL;
+  }
+
+  ScopedPyObjectPtr is_present(MapReflectionFriend::Contains(self, key));
+  if (is_present.get() == NULL) {
+    return NULL;
+  }
+
+  if (PyObject_IsTrue(is_present.get())) {
+    return MapReflectionFriend::MessageMapGetItem(self, key);
+  } else {
+    if (default_value != NULL) {
+      Py_INCREF(default_value);
+      return default_value;
+    } else {
+      Py_RETURN_NONE;
+    }
+  }
+}
+
+static void MessageMapDealloc(PyObject* _self) {
+  MessageMapContainer* self = GetMessageMap(_self);
+  self->owner.reset();
+  Py_DECREF(self->message_dict);
+  Py_TYPE(_self)->tp_free(_self);
+}
+
+static PyMappingMethods MessageMapMappingMethods = {
+  MapReflectionFriend::Length,              // mp_length
+  MapReflectionFriend::MessageMapGetItem,   // mp_subscript
+  MapReflectionFriend::MessageMapSetItem,   // mp_ass_subscript
+};
+
+static PyMethodDef MessageMapMethods[] = {
+  { "__contains__", (PyCFunction)MapReflectionFriend::Contains, METH_O,
+    "Tests whether the map contains this element."},
+  { "clear", (PyCFunction)Clear, METH_NOARGS,
+    "Removes all elements from the map."},
+  { "get", MessageMapGet, METH_VARARGS,
+    "Gets the value for the given key if present, or otherwise a default" },
+  { "get_or_create", MapReflectionFriend::MessageMapGetItem, METH_O,
+    "Alias for getitem, useful to make explicit that the map is mutated." },
+  /*
+  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
+    "Makes a deep copy of the class." },
+  { "__reduce__", (PyCFunction)Reduce, METH_NOARGS,
+    "Outputs picklable representation of the repeated field." },
+  */
+  {NULL, NULL},
+};
+
+PyTypeObject MessageMapContainer_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  FULL_MODULE_NAME ".MessageMapContainer",  //  tp_name
+  sizeof(MessageMapContainer),         //  tp_basicsize
+  0,                                   //  tp_itemsize
+  MessageMapDealloc,                   //  tp_dealloc
+  0,                                   //  tp_print
+  0,                                   //  tp_getattr
+  0,                                   //  tp_setattr
+  0,                                   //  tp_compare
+  0,                                   //  tp_repr
+  0,                                   //  tp_as_number
+  0,                                   //  tp_as_sequence
+  &MessageMapMappingMethods,           //  tp_as_mapping
+  0,                                   //  tp_hash
+  0,                                   //  tp_call
+  0,                                   //  tp_str
+  0,                                   //  tp_getattro
+  0,                                   //  tp_setattro
+  0,                                   //  tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                  //  tp_flags
+  "A map container for message",       //  tp_doc
+  0,                                   //  tp_traverse
+  0,                                   //  tp_clear
+  0,                                   //  tp_richcompare
+  0,                                   //  tp_weaklistoffset
+  MapReflectionFriend::GetIterator,    //  tp_iter
+  0,                                   //  tp_iternext
+  MessageMapMethods,                   //  tp_methods
+  0,                                   //  tp_members
+  0,                                   //  tp_getset
+  0,                                   //  tp_base
+  0,                                   //  tp_dict
+  0,                                   //  tp_descr_get
+  0,                                   //  tp_descr_set
+  0,                                   //  tp_dictoffset
+  0,                                   //  tp_init
+};
+
+// MapIterator /////////////////////////////////////////////////////////////////
+
+static MapIterator* GetIter(PyObject* obj) {
+  return reinterpret_cast<MapIterator*>(obj);
+}
+
+PyObject* MapReflectionFriend::GetIterator(PyObject *_self) {
+  MapContainer* self = GetMap(_self);
+
+  ScopedPyObjectPtr obj(PyType_GenericAlloc(&MapIterator_Type, 0));
+  if (obj == NULL) {
+    return PyErr_Format(PyExc_KeyError, "Could not allocate iterator");
+  }
+
+  MapIterator* iter = GetIter(obj.get());
+
+  Py_INCREF(self);
+  iter->container = self;
+  iter->version = self->version;
+  iter->owner = self->owner;
+
+  if (MapReflectionFriend::Length(_self) > 0) {
+    Message* message = self->GetMutableMessage();
+    const Reflection* reflection = message->GetReflection();
+
+    iter->iter.reset(new ::google::protobuf::MapIterator(
+        reflection->MapBegin(message, self->parent_field_descriptor)));
+  }
+
+  return obj.release();
+}
+
+PyObject* MapReflectionFriend::IterNext(PyObject* _self) {
+  MapIterator* self = GetIter(_self);
+
+  // This won't catch mutations to the map performed by MergeFrom(); no easy way
+  // to address that.
+  if (self->version != self->container->version) {
+    return PyErr_Format(PyExc_RuntimeError,
+                        "Map modified during iteration.");
+  }
+
+  if (self->iter.get() == NULL) {
+    return NULL;
+  }
+
+  Message* message = self->container->GetMutableMessage();
+  const Reflection* reflection = message->GetReflection();
+
+  if (*self->iter ==
+      reflection->MapEnd(message, self->container->parent_field_descriptor)) {
+    return NULL;
+  }
+
+  PyObject* ret = MapKeyToPython(self->container->key_field_descriptor,
+                                 self->iter->GetKey());
+
+  ++(*self->iter);
+
+  return ret;
+}
+
+static void DeallocMapIterator(PyObject* _self) {
+  MapIterator* self = GetIter(_self);
+  self->iter.reset();
+  self->owner.reset();
+  Py_XDECREF(self->container);
+  Py_TYPE(_self)->tp_free(_self);
+}
+
+PyTypeObject MapIterator_Type = {
+  PyVarObject_HEAD_INIT(&PyType_Type, 0)
+  FULL_MODULE_NAME ".MapIterator",     //  tp_name
+  sizeof(MapIterator),                 //  tp_basicsize
+  0,                                   //  tp_itemsize
+  DeallocMapIterator,                  //  tp_dealloc
+  0,                                   //  tp_print
+  0,                                   //  tp_getattr
+  0,                                   //  tp_setattr
+  0,                                   //  tp_compare
+  0,                                   //  tp_repr
+  0,                                   //  tp_as_number
+  0,                                   //  tp_as_sequence
+  0,                                   //  tp_as_mapping
+  0,                                   //  tp_hash
+  0,                                   //  tp_call
+  0,                                   //  tp_str
+  0,                                   //  tp_getattro
+  0,                                   //  tp_setattro
+  0,                                   //  tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                  //  tp_flags
+  "A scalar map iterator",             //  tp_doc
+  0,                                   //  tp_traverse
+  0,                                   //  tp_clear
+  0,                                   //  tp_richcompare
+  0,                                   //  tp_weaklistoffset
+  PyObject_SelfIter,                   //  tp_iter
+  MapReflectionFriend::IterNext,       //  tp_iternext
+  0,                                   //  tp_methods
+  0,                                   //  tp_members
+  0,                                   //  tp_getset
+  0,                                   //  tp_base
+  0,                                   //  tp_dict
+  0,                                   //  tp_descr_get
+  0,                                   //  tp_descr_set
+  0,                                   //  tp_dictoffset
+  0,                                   //  tp_init
+};
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google
diff --git a/python/google/protobuf/pyext/message_map_container.h b/python/google/protobuf/pyext/map_container.h
index 4f6cb26a..2de61187 100644
--- a/python/google/protobuf/pyext/message_map_container.h
+++ b/python/google/protobuf/pyext/map_container.h
@@ -28,8 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_MESSAGE_MAP_CONTAINER_H__
-#define GOOGLE_PROTOBUF_PYTHON_CPP_MESSAGE_MAP_CONTAINER_H__
+#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__
+#define GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__
 
 #include <Python.h>
 
@@ -39,6 +39,7 @@
 #endif
 
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/message.h>
 
 namespace google {
 namespace protobuf {
@@ -55,18 +56,23 @@ namespace python {
 
 struct CMessage;
 
-struct MessageMapContainer {
+// This struct is used directly for ScalarMap, and is the base class of
+// MessageMapContainer, which is used for MessageMap.
+struct MapContainer {
   PyObject_HEAD;
 
   // This is the top-level C++ Message object that owns the whole
-  // proto tree.  Every Python MessageMapContainer holds a
+  // proto tree.  Every Python MapContainer holds a
   // reference to it in order to keep it alive as long as there's a
   // Python object that references any part of the tree.
   shared_ptr<Message> owner;
 
   // Pointer to the C++ Message that contains this container.  The
-  // MessageMapContainer does not own this pointer.
-  Message* message;
+  // MapContainer does not own this pointer.
+  const Message* message;
+
+  // Use to get a mutable message when necessary.
+  Message* GetMutableMessage();
 
   // Weak reference to a parent CMessage object (i.e. may be NULL.)
   //
@@ -82,45 +88,46 @@ struct MessageMapContainer {
   const FieldDescriptor* key_field_descriptor;
   const FieldDescriptor* value_field_descriptor;
 
+  // We bump this whenever we perform a mutation, to invalidate existing
+  // iterators.
+  uint64 version;
+
+  // Releases the messages in the container to a new message.
+  //
+  // Returns 0 on success, -1 on failure.
+  int Release();
+
+  // Set the owner field of self and any children of self.
+  void SetOwner(const shared_ptr<Message>& new_owner) {
+    owner = new_owner;
+  }
+};
+
+struct MessageMapContainer : public MapContainer {
   // A callable that is used to create new child messages.
   PyObject* subclass_init;
 
   // A dict mapping Message* -> CMessage.
   PyObject* message_dict;
-
-  // We bump this whenever we perform a mutation, to invalidate existing
-  // iterators.
-  uint64 version;
 };
 
-#if PY_MAJOR_VERSION >= 3
-  extern PyObject *MessageMapContainer_Type;
-  extern PyType_Spec MessageMapContainer_Type_spec;
-#else
-  extern PyTypeObject MessageMapContainer_Type;
-#endif
-extern PyTypeObject MessageMapIterator_Type;
+extern PyTypeObject ScalarMapContainer_Type;
+extern PyTypeObject MessageMapContainer_Type;
+extern PyTypeObject MapIterator_Type;  // Both map types use the same iterator.
 
-namespace message_map_container {
-
-// Builds a MessageMapContainer object, from a parent message and a
+// Builds a MapContainer object, from a parent message and a
 // field descriptor.
-extern PyObject* NewContainer(CMessage* parent,
-                              const FieldDescriptor* parent_field_descriptor,
-                              PyObject* concrete_class);
-
-// Releases the messages in the container to a new message.
-//
-// Returns 0 on success, -1 on failure.
-int Release(MessageMapContainer* self);
+extern PyObject* NewScalarMapContainer(
+    CMessage* parent, const FieldDescriptor* parent_field_descriptor);
 
-// Set the owner field of self and any children of self.
-void SetOwner(MessageMapContainer* self,
-              const shared_ptr<Message>& new_owner);
+// Builds a MessageMap object, from a parent message and a
+// field descriptor.
+extern PyObject* NewMessageMapContainer(
+    CMessage* parent, const FieldDescriptor* parent_field_descriptor,
+    PyObject* concrete_class);
 
-}  // namespace message_map_container
 }  // namespace python
 }  // namespace protobuf
 
 }  // namespace google
-#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_MESSAGE_MAP_CONTAINER_H__
+#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_MAP_CONTAINER_H__
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index 72f51ec1..863cde01 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -33,6 +33,7 @@
 
 #include <google/protobuf/pyext/message.h>
 
+#include <map>
 #include <memory>
 #ifndef _SHARED_PTR_H
 #include <google/protobuf/stubs/shared_ptr.h>
@@ -61,8 +62,7 @@
 #include <google/protobuf/pyext/extension_dict.h>
 #include <google/protobuf/pyext/repeated_composite_container.h>
 #include <google/protobuf/pyext/repeated_scalar_container.h>
-#include <google/protobuf/pyext/message_map_container.h>
-#include <google/protobuf/pyext/scalar_map_container.h>
+#include <google/protobuf/pyext/map_container.h>
 #include <google/protobuf/pyext/scoped_pyobject_ptr.h>
 #include <google/protobuf/stubs/strutil.h>
 
@@ -96,6 +96,7 @@ static PyObject* k_extensions_by_number;
 PyObject* EnumTypeWrapper_class;
 static PyObject* PythonMessage_class;
 static PyObject* kEmptyWeakref;
+static PyObject* WKT_classes = NULL;
 
 // Defines the Metaclass of all Message classes.
 // It allows us to cache some C++ pointers in the class object itself, they are
@@ -274,8 +275,32 @@ static PyObject* New(PyTypeObject* type,
 
   // Build the arguments to the base metaclass.
   // We change the __bases__ classes.
-  ScopedPyObjectPtr new_args(Py_BuildValue(
-      "s(OO)O", name, &CMessage_Type, PythonMessage_class, dict));
+  ScopedPyObjectPtr new_args;
+  const Descriptor* message_descriptor =
+      PyMessageDescriptor_AsDescriptor(py_descriptor);
+  if (message_descriptor == NULL) {
+    return NULL;
+  }
+
+  if (WKT_classes == NULL) {
+    ScopedPyObjectPtr well_known_types(PyImport_ImportModule(
+        "google.protobuf.internal.well_known_types"));
+    GOOGLE_DCHECK(well_known_types != NULL);
+
+    WKT_classes = PyObject_GetAttrString(well_known_types.get(), "WKTBASES");
+    GOOGLE_DCHECK(WKT_classes != NULL);
+  }
+
+  PyObject* well_known_class = PyDict_GetItemString(
+      WKT_classes, message_descriptor->full_name().c_str());
+  if (well_known_class == NULL) {
+    new_args.reset(Py_BuildValue("s(OO)O", name, &CMessage_Type,
+                                 PythonMessage_class, dict));
+  } else {
+    new_args.reset(Py_BuildValue("s(OOO)O", name, &CMessage_Type,
+                                 PythonMessage_class, well_known_class, dict));
+  }
+
   if (new_args == NULL) {
     return NULL;
   }
@@ -448,21 +473,9 @@ static int VisitCompositeField(const FieldDescriptor* descriptor,
   if (descriptor->label() == FieldDescriptor::LABEL_REPEATED) {
     if (descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       if (descriptor->is_map()) {
-        const Descriptor* entry_type = descriptor->message_type();
-        const FieldDescriptor* value_type =
-            entry_type->FindFieldByName("value");
-        if (value_type->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
-          MessageMapContainer* container =
-            reinterpret_cast<MessageMapContainer*>(child);
-          if (visitor.VisitMessageMapContainer(container) == -1) {
-            return -1;
-          }
-        } else {
-          ScalarMapContainer* container =
-            reinterpret_cast<ScalarMapContainer*>(child);
-          if (visitor.VisitScalarMapContainer(container) == -1) {
-            return -1;
-          }
+        MapContainer* container = reinterpret_cast<MapContainer*>(child);
+        if (visitor.VisitMapContainer(container) == -1) {
+          return -1;
         }
       } else {
         RepeatedCompositeContainer* container =
@@ -579,12 +592,14 @@ bool CheckAndGetInteger(
   if (PyObject_RichCompareBool(min, arg, Py_LE) != 1 ||
       PyObject_RichCompareBool(max, arg, Py_GE) != 1) {
 #endif
-    PyObject *s = PyObject_Str(arg);
-    if (s) {
-      PyErr_Format(PyExc_ValueError,
-                   "Value out of range: %s",
-                   PyString_AsString(s));
-      Py_DECREF(s);
+    if (!PyErr_Occurred()) {
+      PyObject *s = PyObject_Str(arg);
+      if (s) {
+        PyErr_Format(PyExc_ValueError,
+                     "Value out of range: %s",
+                     PyString_AsString(s));
+        Py_DECREF(s);
+      }
     }
     return false;
   }
@@ -642,38 +657,51 @@ bool CheckAndGetBool(PyObject* arg, bool* value) {
   return true;
 }
 
-bool CheckAndSetString(
-    PyObject* arg, Message* message,
-    const FieldDescriptor* descriptor,
-    const Reflection* reflection,
-    bool append,
-    int index) {
+// Checks whether the given object (which must be "bytes" or "unicode") contains
+// valid UTF-8.
+bool IsValidUTF8(PyObject* obj) {
+  if (PyBytes_Check(obj)) {
+    PyObject* unicode = PyUnicode_FromEncodedObject(obj, "utf-8", NULL);
+
+    // Clear the error indicator; we report our own error when desired.
+    PyErr_Clear();
+
+    if (unicode) {
+      Py_DECREF(unicode);
+      return true;
+    } else {
+      return false;
+    }
+  } else {
+    // Unicode object, known to be valid UTF-8.
+    return true;
+  }
+}
+
+bool AllowInvalidUTF8(const FieldDescriptor* field) { return false; }
+
+PyObject* CheckString(PyObject* arg, const FieldDescriptor* descriptor) {
   GOOGLE_DCHECK(descriptor->type() == FieldDescriptor::TYPE_STRING ||
          descriptor->type() == FieldDescriptor::TYPE_BYTES);
   if (descriptor->type() == FieldDescriptor::TYPE_STRING) {
     if (!PyBytes_Check(arg) && !PyUnicode_Check(arg)) {
       FormatTypeError(arg, "bytes, unicode");
-      return false;
+      return NULL;
     }
 
-    if (PyBytes_Check(arg)) {
-      PyObject* unicode = PyUnicode_FromEncodedObject(arg, "utf-8", NULL);
-      if (unicode == NULL) {
-        PyObject* repr = PyObject_Repr(arg);
-        PyErr_Format(PyExc_ValueError,
-                     "%s has type str, but isn't valid UTF-8 "
-                     "encoding. Non-UTF-8 strings must be converted to "
-                     "unicode objects before being added.",
-                     PyString_AsString(repr));
-        Py_DECREF(repr);
-        return false;
-      } else {
-        Py_DECREF(unicode);
-      }
+    if (!IsValidUTF8(arg) && !AllowInvalidUTF8(descriptor)) {
+      PyObject* repr = PyObject_Repr(arg);
+      PyErr_Format(PyExc_ValueError,
+                   "%s has type str, but isn't valid UTF-8 "
+                   "encoding. Non-UTF-8 strings must be converted to "
+                   "unicode objects before being added.",
+                   PyString_AsString(repr));
+      Py_DECREF(repr);
+      return NULL;
     }
   } else if (!PyBytes_Check(arg)) {
     FormatTypeError(arg, "bytes");
-    return false;
+    return NULL;
   }
 
   PyObject* encoded_string = NULL;
@@ -691,14 +719,24 @@ bool CheckAndSetString(
     Py_INCREF(encoded_string);
   }
 
-  if (encoded_string == NULL) {
+  return encoded_string;
+}
+
+bool CheckAndSetString(
+    PyObject* arg, Message* message,
+    const FieldDescriptor* descriptor,
+    const Reflection* reflection,
+    bool append,
+    int index) {
+  ScopedPyObjectPtr encoded_string(CheckString(arg, descriptor));
+
+  if (encoded_string.get() == NULL) {
     return false;
   }
 
   char* value;
   Py_ssize_t value_len;
-  if (PyBytes_AsStringAndSize(encoded_string, &value, &value_len) < 0) {
-    Py_DECREF(encoded_string);
+  if (PyBytes_AsStringAndSize(encoded_string.get(), &value, &value_len) < 0) {
     return false;
   }
 
@@ -710,7 +748,6 @@ bool CheckAndSetString(
   } else {
     reflection->SetRepeatedString(message, descriptor, index, value_string);
   }
-  Py_DECREF(encoded_string);
   return true;
 }
 
@@ -823,12 +860,7 @@ struct FixupMessageReference : public ChildVisitor {
     return 0;
   }
 
-  int VisitScalarMapContainer(ScalarMapContainer* container) {
-    container->message = message_;
-    return 0;
-  }
-
-  int VisitMessageMapContainer(MessageMapContainer* container) {
+  int VisitMapContainer(MapContainer* container) {
     container->message = message_;
     return 0;
   }
@@ -870,9 +902,8 @@ int AssureWritable(CMessage* self) {
   // When a CMessage is made writable its Message pointer is updated
   // to point to a new mutable Message.  When that happens we need to
   // update any references to the old, read-only CMessage.  There are
-  // five places such references occur: RepeatedScalarContainer,
-  // RepeatedCompositeContainer, ScalarMapContainer, MessageMapContainer,
-  // and ExtensionDict.
+  // four places such references occur: RepeatedScalarContainer,
+  // RepeatedCompositeContainer, MapContainer, and ExtensionDict.
   if (self->extensions != NULL)
     self->extensions->message = self->message;
   if (ForEachCompositeField(self, FixupMessageReference(self->message)) == -1)
@@ -1054,7 +1085,8 @@ int InitAttributes(CMessage* self, PyObject* kwargs) {
     }
     const FieldDescriptor* descriptor = GetFieldDescriptor(self, name);
     if (descriptor == NULL) {
-      PyErr_Format(PyExc_ValueError, "Protocol message has no \"%s\" field.",
+      PyErr_Format(PyExc_ValueError, "Protocol message %s has no \"%s\" field.",
+                   self->message->GetDescriptor()->name().c_str(),
                    PyString_AsString(name));
       return -1;
     }
@@ -1203,18 +1235,6 @@ CMessage* NewEmptyMessage(PyObject* type, const Descriptor *descriptor) {
 
   self->composite_fields = NULL;
 
-  // If there are extension_ranges, the message is "extendable". Allocate a
-  // dictionary to store the extension fields.
-  if (descriptor->extension_range_count() > 0) {
-    // TODO(amauryfa): Delay the construction of this dict until extensions are
-    // really used on the object.
-    ExtensionDict* extension_dict = extension_dict::NewExtensionDict(self);
-    if (extension_dict == NULL) {
-      return NULL;
-    }
-    self->extensions = extension_dict;
-  }
-
   return self;
 }
 
@@ -1285,12 +1305,7 @@ struct ClearWeakReferences : public ChildVisitor {
     return 0;
   }
 
-  int VisitScalarMapContainer(ScalarMapContainer* container) {
-    container->parent = NULL;
-    return 0;
-  }
-
-  int VisitMessageMapContainer(MessageMapContainer* container) {
+  int VisitMapContainer(MapContainer* container) {
     container->parent = NULL;
     return 0;
   }
@@ -1305,6 +1320,9 @@ struct ClearWeakReferences : public ChildVisitor {
 static void Dealloc(CMessage* self) {
   // Null out all weak references from children to this message.
   GOOGLE_CHECK_EQ(0, ForEachCompositeField(self, ClearWeakReferences()));
+  if (self->extensions) {
+    self->extensions->parent = NULL;
+  }
 
   Py_CLEAR(self->extensions);
   Py_CLEAR(self->composite_fields);
@@ -1466,20 +1484,27 @@ PyObject* HasField(CMessage* self, PyObject* arg) {
   Py_RETURN_FALSE;
 }
 
-PyObject* ClearExtension(CMessage* self, PyObject* arg) {
+PyObject* ClearExtension(CMessage* self, PyObject* extension) {
   if (self->extensions != NULL) {
-    return extension_dict::ClearExtension(self->extensions, arg);
+    return extension_dict::ClearExtension(self->extensions, extension);
+  } else {
+    const FieldDescriptor* descriptor = GetExtensionDescriptor(extension);
+    if (descriptor == NULL) {
+      return NULL;
+    }
+    if (ScopedPyObjectPtr(ClearFieldByDescriptor(self, descriptor)) == NULL) {
+      return NULL;
+    }
   }
-  PyErr_SetString(PyExc_TypeError, "Message is not extendable");
-  return NULL;
+  Py_RETURN_NONE;
 }
 
-PyObject* HasExtension(CMessage* self, PyObject* arg) {
-  if (self->extensions != NULL) {
-    return extension_dict::HasExtension(self->extensions, arg);
+PyObject* HasExtension(CMessage* self, PyObject* extension) {
+  const FieldDescriptor* descriptor = GetExtensionDescriptor(extension);
+  if (descriptor == NULL) {
+    return NULL;
   }
-  PyErr_SetString(PyExc_TypeError, "Message is not extendable");
-  return NULL;
+  return HasFieldByDescriptor(self, descriptor);
 }
 
 // ---------------------------------------------------------------------
@@ -1529,13 +1554,8 @@ struct SetOwnerVisitor : public ChildVisitor {
     return 0;
   }
 
-  int VisitScalarMapContainer(ScalarMapContainer* container) {
-    scalar_map_container::SetOwner(container, new_owner_);
-    return 0;
-  }
-
-  int VisitMessageMapContainer(MessageMapContainer* container) {
-    message_map_container::SetOwner(container, new_owner_);
+  int VisitMapContainer(MapContainer* container) {
+    container->SetOwner(new_owner_);
     return 0;
   }
 
@@ -1608,14 +1628,8 @@ struct ReleaseChild : public ChildVisitor {
         reinterpret_cast<RepeatedScalarContainer*>(container));
   }
 
-  int VisitScalarMapContainer(ScalarMapContainer* container) {
-    return scalar_map_container::Release(
-        reinterpret_cast<ScalarMapContainer*>(container));
-  }
-
-  int VisitMessageMapContainer(MessageMapContainer* container) {
-    return message_map_container::Release(
-        reinterpret_cast<MessageMapContainer*>(container));
+  int VisitMapContainer(MapContainer* container) {
+    return reinterpret_cast<MapContainer*>(container)->Release();
   }
 
   int VisitCMessage(CMessage* cmessage,
@@ -1707,17 +1721,7 @@ PyObject* Clear(CMessage* self) {
   AssureWritable(self);
   if (ForEachCompositeField(self, ReleaseChild(self)) == -1)
     return NULL;
-
-  // The old ExtensionDict still aliases this CMessage, but all its
-  // fields have been released.
-  if (self->extensions != NULL) {
-    Py_CLEAR(self->extensions);
-    ExtensionDict* extension_dict = extension_dict::NewExtensionDict(self);
-    if (extension_dict == NULL) {
-      return NULL;
-    }
-    self->extensions = extension_dict;
-  }
+  Py_CLEAR(self->extensions);
   if (self->composite_fields) {
     PyDict_Clear(self->composite_fields);
   }
@@ -1997,7 +2001,6 @@ static PyObject* RegisterExtension(PyObject* cls,
   if (descriptor->is_extension() &&
       descriptor->containing_type()->options().message_set_wire_format() &&
       descriptor->type() == FieldDescriptor::TYPE_MESSAGE &&
-      descriptor->message_type() == descriptor->extension_scope() &&
       descriptor->label() == FieldDescriptor::LABEL_OPTIONAL) {
     ScopedPyObjectPtr message_name(PyString_FromStringAndSize(
         descriptor->message_type()->full_name().c_str(),
@@ -2042,6 +2045,8 @@ static PyObject* WhichOneof(CMessage* self, PyObject* arg) {
   }
 }
 
+static PyObject* GetExtensionDict(CMessage* self, void *closure);
+
 static PyObject* ListFields(CMessage* self) {
   vector<const FieldDescriptor*> fields;
   self->message->GetReflection()->ListFields(*self->message, &fields);
@@ -2079,12 +2084,13 @@ static PyObject* ListFields(CMessage* self) {
         PyErr_Clear();
         continue;
       }
-      PyObject* extensions = reinterpret_cast<PyObject*>(self->extensions);
+      ScopedPyObjectPtr extensions(GetExtensionDict(self, NULL));
       if (extensions == NULL) {
         return NULL;
       }
       // 'extension' reference later stolen by PyTuple_SET_ITEM.
-      PyObject* extension = PyObject_GetItem(extensions, extension_field.get());
+      PyObject* extension = PyObject_GetItem(
+          extensions.get(), extension_field.get());
       if (extension == NULL) {
         return NULL;
       }
@@ -2493,9 +2499,31 @@ PyObject* _CheckCalledFromGeneratedFile(PyObject* unused,
   Py_RETURN_NONE;
 }
 
-static PyMemberDef Members[] = {
-  {"Extensions", T_OBJECT_EX, offsetof(CMessage, extensions), 0,
-   "Extension dict"},
+static PyObject* GetExtensionDict(CMessage* self, void *closure) {
+  if (self->extensions)  {
+    Py_INCREF(self->extensions);
+    return reinterpret_cast<PyObject*>(self->extensions);
+  }
+
+  // If there are extension_ranges, the message is "extendable". Allocate a
+  // dictionary to store the extension fields.
+  const Descriptor* descriptor = GetMessageDescriptor(Py_TYPE(self));
+  if (descriptor->extension_range_count() > 0) {
+    ExtensionDict* extension_dict = extension_dict::NewExtensionDict(self);
+    if (extension_dict == NULL) {
+      return NULL;
+    }
+    self->extensions = extension_dict;
+    Py_INCREF(self->extensions);
+    return reinterpret_cast<PyObject*>(self->extensions);
+  }
+
+  PyErr_SetNone(PyExc_AttributeError);
+  return NULL;
+}
+
+static PyGetSetDef Getters[] = {
+  {"Extensions", (getter)GetExtensionDict, NULL, "Extension dict"},
   {NULL}
 };
 
@@ -2592,10 +2620,10 @@ PyObject* GetAttr(CMessage* self, PyObject* name) {
       if (value_class == NULL) {
         return NULL;
       }
-      py_container = message_map_container::NewContainer(self, field_descriptor,
-                                                         value_class);
+      py_container =
+          NewMessageMapContainer(self, field_descriptor, value_class);
     } else {
-      py_container = scalar_map_container::NewContainer(self, field_descriptor);
+      py_container = NewScalarMapContainer(self, field_descriptor);
     }
     if (py_container == NULL) {
       return NULL;
@@ -2672,7 +2700,10 @@ int SetAttr(CMessage* self, PyObject* name, PyObject* value) {
     }
   }
 
-  PyErr_Format(PyExc_AttributeError, "Assignment not allowed");
+  PyErr_Format(PyExc_AttributeError,
+               "Assignment not allowed "
+               "(no field \"%s\"in protocol message object).",
+               PyString_AsString(name));
   return -1;
 }
 
@@ -2707,8 +2738,8 @@ PyTypeObject CMessage_Type = {
   0,                                   //  tp_iter
   0,                                   //  tp_iternext
   cmessage::Methods,                   //  tp_methods
-  cmessage::Members,                   //  tp_members
-  0,                                   //  tp_getset
+  0,                                   //  tp_members
+  cmessage::Getters,                   //  tp_getset
   0,                                   //  tp_base
   0,                                   //  tp_dict
   0,                                   //  tp_descr_get
@@ -2910,12 +2941,12 @@ bool InitProto2MessageModule(PyObject *m) {
                        reinterpret_cast<PyObject*>(&ScalarMapContainer_Type));
 #endif
 
-    if (PyType_Ready(&ScalarMapIterator_Type) < 0) {
+    if (PyType_Ready(&MapIterator_Type) < 0) {
       return false;
     }
 
-    PyModule_AddObject(m, "ScalarMapIterator",
-                       reinterpret_cast<PyObject*>(&ScalarMapIterator_Type));
+    PyModule_AddObject(m, "MapIterator",
+                       reinterpret_cast<PyObject*>(&MapIterator_Type));
 
 
 #if PY_MAJOR_VERSION >= 3
@@ -2934,13 +2965,6 @@ bool InitProto2MessageModule(PyObject *m) {
     PyModule_AddObject(m, "MessageMapContainer",
                        reinterpret_cast<PyObject*>(&MessageMapContainer_Type));
 #endif
-
-    if (PyType_Ready(&MessageMapIterator_Type) < 0) {
-      return false;
-    }
-
-    PyModule_AddObject(m, "MessageMapIterator",
-                       reinterpret_cast<PyObject*>(&MessageMapIterator_Type));
   }
 
   if (PyType_Ready(&ExtensionDict_Type) < 0) {
@@ -2957,6 +2981,9 @@ bool InitProto2MessageModule(PyObject *m) {
   PyModule_AddObject(m, "default_pool",
                      reinterpret_cast<PyObject*>(GetDefaultDescriptorPool()));
 
+  PyModule_AddObject(m, "DescriptorPool", reinterpret_cast<PyObject*>(
+      &PyDescriptorPool_Type));
+
   // This implementation provides full Descriptor types, we advertise it so that
   // descriptor.py can use them in replacement of the Python classes.
   PyModule_AddIntConstant(m, "_USE_C_DESCRIPTORS", 1);
diff --git a/python/google/protobuf/pyext/message.h b/python/google/protobuf/pyext/message.h
index 94de4551..cc0012e9 100644
--- a/python/google/protobuf/pyext/message.h
+++ b/python/google/protobuf/pyext/message.h
@@ -307,6 +307,7 @@ bool CheckAndGetInteger(
 bool CheckAndGetDouble(PyObject* arg, double* value);
 bool CheckAndGetFloat(PyObject* arg, float* value);
 bool CheckAndGetBool(PyObject* arg, bool* value);
+PyObject* CheckString(PyObject* arg, const FieldDescriptor* descriptor);
 bool CheckAndSetString(
     PyObject* arg, Message* message,
     const FieldDescriptor* descriptor,
diff --git a/python/google/protobuf/pyext/message_map_container.cc b/python/google/protobuf/pyext/message_map_container.cc
deleted file mode 100644
index 8902fa00..00000000
--- a/python/google/protobuf/pyext/message_map_container.cc
+++ /dev/null
@@ -1,569 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Author: haberman@google.com (Josh Haberman)
-
-#include <google/protobuf/pyext/message_map_container.h>
-
-#include <google/protobuf/stubs/logging.h>
-#include <google/protobuf/stubs/common.h>
-#include <google/protobuf/message.h>
-#include <google/protobuf/pyext/message.h>
-#include <google/protobuf/pyext/scoped_pyobject_ptr.h>
-
-namespace google {
-namespace protobuf {
-namespace python {
-
-struct MessageMapIterator {
-  PyObject_HEAD;
-
-  // This dict contains the full contents of what we want to iterate over.
-  // There's no way to avoid building this, because the list representation
-  // (which is canonical) can contain duplicate keys.  So at the very least we
-  // need a set that lets us skip duplicate keys.  And at the point that we're
-  // doing that, we might as well just build the actual dict we're iterating
-  // over and use dict's built-in iterator.
-  PyObject* dict;
-
-  // An iterator on dict.
-  PyObject* iter;
-
-  // A pointer back to the container, so we can notice changes to the version.
-  MessageMapContainer* container;
-
-  // The version of the map when we took the iterator to it.
-  //
-  // We store this so that if the map is modified during iteration we can throw
-  // an error.
-  uint64 version;
-};
-
-static MessageMapIterator* GetIter(PyObject* obj) {
-  return reinterpret_cast<MessageMapIterator*>(obj);
-}
-
-namespace message_map_container {
-
-static MessageMapContainer* GetMap(PyObject* obj) {
-  return reinterpret_cast<MessageMapContainer*>(obj);
-}
-
-// The private constructor of MessageMapContainer objects.
-PyObject* NewContainer(CMessage* parent,
-                       const google::protobuf::FieldDescriptor* parent_field_descriptor,
-                       PyObject* concrete_class) {
-  if (!CheckFieldBelongsToMessage(parent_field_descriptor, parent->message)) {
-    return NULL;
-  }
-
-#if PY_MAJOR_VERSION >= 3
-  PyObject* obj = PyType_GenericAlloc(
-        reinterpret_cast<PyTypeObject *>(MessageMapContainer_Type), 0);
-#else
-  PyObject* obj = PyType_GenericAlloc(&MessageMapContainer_Type, 0);
-#endif
-  if (obj == NULL) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Could not allocate new container.");
-  }
-
-  MessageMapContainer* self = GetMap(obj);
-
-  self->message = parent->message;
-  self->parent = parent;
-  self->parent_field_descriptor = parent_field_descriptor;
-  self->owner = parent->owner;
-  self->version = 0;
-
-  self->key_field_descriptor =
-      parent_field_descriptor->message_type()->FindFieldByName("key");
-  self->value_field_descriptor =
-      parent_field_descriptor->message_type()->FindFieldByName("value");
-
-  self->message_dict = PyDict_New();
-  if (self->message_dict == NULL) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Could not allocate message dict.");
-  }
-
-  Py_INCREF(concrete_class);
-  self->subclass_init = concrete_class;
-
-  if (self->key_field_descriptor == NULL ||
-      self->value_field_descriptor == NULL) {
-    Py_DECREF(obj);
-    return PyErr_Format(PyExc_KeyError,
-                        "Map entry descriptor did not have key/value fields");
-  }
-
-  return obj;
-}
-
-// Initializes the underlying Message object of "to" so it becomes a new parent
-// repeated scalar, and copies all the values from "from" to it. A child scalar
-// container can be released by passing it as both from and to (e.g. making it
-// the recipient of the new parent message and copying the values from itself).
-static int InitializeAndCopyToParentContainer(
-    MessageMapContainer* from,
-    MessageMapContainer* to) {
-  // For now we require from == to, re-evaluate if we want to support deep copy
-  // as in repeated_composite_container.cc.
-  GOOGLE_DCHECK(from == to);
-  Message* old_message = from->message;
-  Message* new_message = old_message->New();
-  to->parent = NULL;
-  to->parent_field_descriptor = from->parent_field_descriptor;
-  to->message = new_message;
-  to->owner.reset(new_message);
-
-  vector<const FieldDescriptor*> fields;
-  fields.push_back(from->parent_field_descriptor);
-  old_message->GetReflection()->SwapFields(old_message, new_message, fields);
-  return 0;
-}
-
-static PyObject* GetCMessage(MessageMapContainer* self, Message* entry) {
-  // Get or create the CMessage object corresponding to this message.
-  Message* message = entry->GetReflection()->MutableMessage(
-      entry, self->value_field_descriptor);
-  ScopedPyObjectPtr key(PyLong_FromVoidPtr(message));
-  PyObject* ret = PyDict_GetItem(self->message_dict, key.get());
-
-  if (ret == NULL) {
-    CMessage* cmsg = cmessage::NewEmptyMessage(self->subclass_init,
-                                               message->GetDescriptor());
-    ret = reinterpret_cast<PyObject*>(cmsg);
-
-    if (cmsg == NULL) {
-      return NULL;
-    }
-    cmsg->owner = self->owner;
-    cmsg->message = message;
-    cmsg->parent = self->parent;
-
-    if (PyDict_SetItem(self->message_dict, key.get(), ret) < 0) {
-      Py_DECREF(ret);
-      return NULL;
-    }
-  } else {
-    Py_INCREF(ret);
-  }
-
-  return ret;
-}
-
-int Release(MessageMapContainer* self) {
-  InitializeAndCopyToParentContainer(self, self);
-  return 0;
-}
-
-void SetOwner(MessageMapContainer* self,
-              const shared_ptr<Message>& new_owner) {
-  self->owner = new_owner;
-}
-
-Py_ssize_t Length(PyObject* _self) {
-  MessageMapContainer* self = GetMap(_self);
-  google::protobuf::Message* message = self->message;
-  return message->GetReflection()->FieldSize(*message,
-                                             self->parent_field_descriptor);
-}
-
-int MapKeyMatches(MessageMapContainer* self, const Message* entry,
-                  PyObject* key) {
-  // TODO(haberman): do we need more strict type checking?
-  ScopedPyObjectPtr entry_key(
-      cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-  int ret = PyObject_RichCompareBool(key, entry_key.get(), Py_EQ);
-  return ret;
-}
-
-int SetItem(PyObject *_self, PyObject *key, PyObject *v) {
-  if (v) {
-    PyErr_Format(PyExc_ValueError,
-                 "Direct assignment of submessage not allowed");
-    return -1;
-  }
-
-  // Now we know that this is a delete, not a set.
-
-  MessageMapContainer* self = GetMap(_self);
-  cmessage::AssureWritable(self->parent);
-
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-  size_t size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.  We need to search from the end because the underlying
-  // representation can have duplicates if a user calls MergeFrom(); the last
-  // one needs to win.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  bool found = false;
-  for (int i = size - 1; i >= 0; i--) {
-    Message* entry = reflection->MutableRepeatedMessage(
-        message, self->parent_field_descriptor, i);
-    int matches = MapKeyMatches(self, entry, key);
-    if (matches < 0) return -1;
-    if (matches) {
-      found = true;
-      if (i != (int)size - 1) {
-        reflection->SwapElements(message, self->parent_field_descriptor, i,
-                                 size - 1);
-      }
-      reflection->RemoveLast(message, self->parent_field_descriptor);
-
-      // Can't exit now, the repeated field representation of maps allows
-      // duplicate keys, and we have to be sure to remove all of them.
-    }
-  }
-
-  if (!found) {
-    PyErr_Format(PyExc_KeyError, "Key not present in map");
-    return -1;
-  }
-
-  self->version++;
-
-  return 0;
-}
-
-PyObject* GetIterator(PyObject *_self) {
-  MessageMapContainer* self = GetMap(_self);
-
-  ScopedPyObjectPtr obj(PyType_GenericAlloc(&MessageMapIterator_Type, 0));
-  if (obj == NULL) {
-    return PyErr_Format(PyExc_KeyError, "Could not allocate iterator");
-  }
-
-  MessageMapIterator* iter = GetIter(obj.get());
-
-  Py_INCREF(self);
-  iter->container = self;
-  iter->version = self->version;
-  iter->dict = PyDict_New();
-  if (iter->dict == NULL) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Could not allocate dict for iterator.");
-  }
-
-  // Build the entire map into a dict right now.  Start from the beginning so
-  // that later entries win in the case of duplicates.
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.  We need to search from the end because the underlying
-  // representation can have duplicates if a user calls MergeFrom(); the last
-  // one needs to win.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  size_t size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = size - 1; i >= 0; i--) {
-    Message* entry = reflection->MutableRepeatedMessage(
-        message, self->parent_field_descriptor, i);
-    ScopedPyObjectPtr key(
-        cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-    if (PyDict_SetItem(iter->dict, key.get(), GetCMessage(self, entry)) < 0) {
-      return PyErr_Format(PyExc_RuntimeError,
-                          "SetItem failed in iterator construction.");
-    }
-  }
-
-  iter->iter = PyObject_GetIter(iter->dict);
-
-  return obj.release();
-}
-
-PyObject* GetItem(PyObject* _self, PyObject* key) {
-  MessageMapContainer* self = GetMap(_self);
-  cmessage::AssureWritable(self->parent);
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.  We need to search from the end because the underlying
-  // representation can have duplicates if a user calls MergeFrom(); the last
-  // one needs to win.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  size_t size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = size - 1; i >= 0; i--) {
-    Message* entry = reflection->MutableRepeatedMessage(
-        message, self->parent_field_descriptor, i);
-    int matches = MapKeyMatches(self, entry, key);
-    if (matches < 0) return NULL;
-    if (matches) {
-      return GetCMessage(self, entry);
-    }
-  }
-
-  // Key is not already present; insert a new entry.
-  Message* entry =
-      reflection->AddMessage(message, self->parent_field_descriptor);
-
-  self->version++;
-
-  if (cmessage::InternalSetNonOneofScalar(entry, self->key_field_descriptor,
-                                          key) < 0) {
-    reflection->RemoveLast(message, self->parent_field_descriptor);
-    return NULL;
-  }
-
-  return GetCMessage(self, entry);
-}
-
-PyObject* Contains(PyObject* _self, PyObject* key) {
-  MessageMapContainer* self = GetMap(_self);
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  int size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = 0; i < size; i++) {
-    Message* entry = reflection->MutableRepeatedMessage(
-        message, self->parent_field_descriptor, i);
-    int matches = MapKeyMatches(self, entry, key);
-    if (matches < 0) return NULL;
-    if (matches) {
-      Py_RETURN_TRUE;
-    }
-  }
-
-  Py_RETURN_FALSE;
-}
-
-PyObject* Clear(PyObject* _self) {
-  MessageMapContainer* self = GetMap(_self);
-  cmessage::AssureWritable(self->parent);
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  self->version++;
-  reflection->ClearField(message, self->parent_field_descriptor);
-
-  Py_RETURN_NONE;
-}
-
-PyObject* Get(PyObject* self, PyObject* args) {
-  PyObject* key;
-  PyObject* default_value = NULL;
-  if (PyArg_ParseTuple(args, "O|O", &key, &default_value) < 0) {
-    return NULL;
-  }
-
-  ScopedPyObjectPtr is_present(Contains(self, key));
-  if (is_present.get() == NULL) {
-    return NULL;
-  }
-
-  if (PyObject_IsTrue(is_present.get())) {
-    return GetItem(self, key);
-  } else {
-    if (default_value != NULL) {
-      Py_INCREF(default_value);
-      return default_value;
-    } else {
-      Py_RETURN_NONE;
-    }
-  }
-}
-
-static void Dealloc(PyObject* _self) {
-  MessageMapContainer* self = GetMap(_self);
-  self->owner.reset();
-  Py_DECREF(self->message_dict);
-  Py_TYPE(_self)->tp_free(_self);
-}
-
-static PyMethodDef Methods[] = {
-  { "__contains__", (PyCFunction)Contains, METH_O,
-    "Tests whether the map contains this element."},
-  { "clear", (PyCFunction)Clear, METH_NOARGS,
-    "Removes all elements from the map."},
-  { "get", Get, METH_VARARGS,
-    "Gets the value for the given key if present, or otherwise a default" },
-  { "get_or_create", GetItem, METH_O,
-    "Alias for getitem, useful to make explicit that the map is mutated." },
-  /*
-  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
-    "Makes a deep copy of the class." },
-  { "__reduce__", (PyCFunction)Reduce, METH_NOARGS,
-    "Outputs picklable representation of the repeated field." },
-  */
-  {NULL, NULL},
-};
-
-}  // namespace message_map_container
-
-namespace message_map_iterator {
-
-static void Dealloc(PyObject* _self) {
-  MessageMapIterator* self = GetIter(_self);
-  Py_DECREF(self->dict);
-  Py_DECREF(self->iter);
-  Py_DECREF(self->container);
-  Py_TYPE(_self)->tp_free(_self);
-}
-
-PyObject* IterNext(PyObject* _self) {
-  MessageMapIterator* self = GetIter(_self);
-
-  // This won't catch mutations to the map performed by MergeFrom(); no easy way
-  // to address that.
-  if (self->version != self->container->version) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Map modified during iteration.");
-  }
-
-  return PyIter_Next(self->iter);
-}
-
-}  // namespace message_map_iterator
-
-#if PY_MAJOR_VERSION >= 3
-  static PyType_Slot MessageMapContainer_Type_slots[] = {
-      {Py_tp_dealloc, (void *)message_map_container::Dealloc},
-      {Py_mp_length, (void *)message_map_container::Length},
-      {Py_mp_subscript, (void *)message_map_container::GetItem},
-      {Py_mp_ass_subscript, (void *)message_map_container::SetItem},
-      {Py_tp_methods, (void *)message_map_container::Methods},
-      {Py_tp_iter, (void *)message_map_container::GetIterator},
-      {0, 0}
-  };
-
-  PyType_Spec MessageMapContainer_Type_spec = {
-      FULL_MODULE_NAME ".MessageMapContainer",
-      sizeof(MessageMapContainer),
-      0,
-      Py_TPFLAGS_DEFAULT,
-      MessageMapContainer_Type_slots
-  };
-
-  PyObject *MessageMapContainer_Type;
-
-#else
-  static PyMappingMethods MpMethods = {
-    message_map_container::Length,    // mp_length
-    message_map_container::GetItem,   // mp_subscript
-    message_map_container::SetItem,   // mp_ass_subscript
-  };
-
-  PyTypeObject MessageMapContainer_Type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
-    FULL_MODULE_NAME ".MessageMapContainer",  //  tp_name
-    sizeof(MessageMapContainer),         //  tp_basicsize
-    0,                                   //  tp_itemsize
-    message_map_container::Dealloc,      //  tp_dealloc
-    0,                                   //  tp_print
-    0,                                   //  tp_getattr
-    0,                                   //  tp_setattr
-    0,                                   //  tp_compare
-    0,                                   //  tp_repr
-    0,                                   //  tp_as_number
-    0,                                   //  tp_as_sequence
-    &MpMethods,                          //  tp_as_mapping
-    0,                                   //  tp_hash
-    0,                                   //  tp_call
-    0,                                   //  tp_str
-    0,                                   //  tp_getattro
-    0,                                   //  tp_setattro
-    0,                                   //  tp_as_buffer
-    Py_TPFLAGS_DEFAULT,                  //  tp_flags
-    "A map container for message",       //  tp_doc
-    0,                                   //  tp_traverse
-    0,                                   //  tp_clear
-    0,                                   //  tp_richcompare
-    0,                                   //  tp_weaklistoffset
-    message_map_container::GetIterator,  //  tp_iter
-    0,                                   //  tp_iternext
-    message_map_container::Methods,      //  tp_methods
-    0,                                   //  tp_members
-    0,                                   //  tp_getset
-    0,                                   //  tp_base
-    0,                                   //  tp_dict
-    0,                                   //  tp_descr_get
-    0,                                   //  tp_descr_set
-    0,                                   //  tp_dictoffset
-    0,                                   //  tp_init
-  };
-#endif
-
-PyTypeObject MessageMapIterator_Type = {
-  PyVarObject_HEAD_INIT(&PyType_Type, 0)
-  FULL_MODULE_NAME ".MessageMapIterator",  //  tp_name
-  sizeof(MessageMapIterator),          //  tp_basicsize
-  0,                                   //  tp_itemsize
-  message_map_iterator::Dealloc,       //  tp_dealloc
-  0,                                   //  tp_print
-  0,                                   //  tp_getattr
-  0,                                   //  tp_setattr
-  0,                                   //  tp_compare
-  0,                                   //  tp_repr
-  0,                                   //  tp_as_number
-  0,                                   //  tp_as_sequence
-  0,                                   //  tp_as_mapping
-  0,                                   //  tp_hash
-  0,                                   //  tp_call
-  0,                                   //  tp_str
-  0,                                   //  tp_getattro
-  0,                                   //  tp_setattro
-  0,                                   //  tp_as_buffer
-  Py_TPFLAGS_DEFAULT,                  //  tp_flags
-  "A scalar map iterator",             //  tp_doc
-  0,                                   //  tp_traverse
-  0,                                   //  tp_clear
-  0,                                   //  tp_richcompare
-  0,                                   //  tp_weaklistoffset
-  PyObject_SelfIter,                   //  tp_iter
-  message_map_iterator::IterNext,       //  tp_iternext
-  0,                                   //  tp_methods
-  0,                                   //  tp_members
-  0,                                   //  tp_getset
-  0,                                   //  tp_base
-  0,                                   //  tp_dict
-  0,                                   //  tp_descr_get
-  0,                                   //  tp_descr_set
-  0,                                   //  tp_dictoffset
-  0,                                   //  tp_init
-};
-
-}  // namespace python
-}  // namespace protobuf
-}  // namespace google
diff --git a/python/google/protobuf/pyext/scalar_map_container.cc b/python/google/protobuf/pyext/scalar_map_container.cc
deleted file mode 100644
index 0b0d5a3d..00000000
--- a/python/google/protobuf/pyext/scalar_map_container.cc
+++ /dev/null
@@ -1,542 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Author: haberman@google.com (Josh Haberman)
-
-#include <google/protobuf/pyext/scalar_map_container.h>
-
-#include <google/protobuf/stubs/logging.h>
-#include <google/protobuf/stubs/common.h>
-#include <google/protobuf/message.h>
-#include <google/protobuf/pyext/message.h>
-#include <google/protobuf/pyext/scoped_pyobject_ptr.h>
-
-namespace google {
-namespace protobuf {
-namespace python {
-
-struct ScalarMapIterator {
-  PyObject_HEAD;
-
-  // This dict contains the full contents of what we want to iterate over.
-  // There's no way to avoid building this, because the list representation
-  // (which is canonical) can contain duplicate keys.  So at the very least we
-  // need a set that lets us skip duplicate keys.  And at the point that we're
-  // doing that, we might as well just build the actual dict we're iterating
-  // over and use dict's built-in iterator.
-  PyObject* dict;
-
-  // An iterator on dict.
-  PyObject* iter;
-
-  // A pointer back to the container, so we can notice changes to the version.
-  ScalarMapContainer* container;
-
-  // The version of the map when we took the iterator to it.
-  //
-  // We store this so that if the map is modified during iteration we can throw
-  // an error.
-  uint64 version;
-};
-
-static ScalarMapIterator* GetIter(PyObject* obj) {
-  return reinterpret_cast<ScalarMapIterator*>(obj);
-}
-
-namespace scalar_map_container {
-
-static ScalarMapContainer* GetMap(PyObject* obj) {
-  return reinterpret_cast<ScalarMapContainer*>(obj);
-}
-
-// The private constructor of ScalarMapContainer objects.
-PyObject *NewContainer(
-    CMessage* parent, const google::protobuf::FieldDescriptor* parent_field_descriptor) {
-  if (!CheckFieldBelongsToMessage(parent_field_descriptor, parent->message)) {
-    return NULL;
-  }
-
-#if PY_MAJOR_VERSION >= 3
-  ScopedPyObjectPtr obj(PyType_GenericAlloc(
-        reinterpret_cast<PyTypeObject *>(ScalarMapContainer_Type), 0));
-#else
-  ScopedPyObjectPtr obj(PyType_GenericAlloc(&ScalarMapContainer_Type, 0));
-#endif
-  if (obj.get() == NULL) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Could not allocate new container.");
-  }
-
-  ScalarMapContainer* self = GetMap(obj.get());
-
-  self->message = parent->message;
-  self->parent = parent;
-  self->parent_field_descriptor = parent_field_descriptor;
-  self->owner = parent->owner;
-  self->version = 0;
-
-  self->key_field_descriptor =
-      parent_field_descriptor->message_type()->FindFieldByName("key");
-  self->value_field_descriptor =
-      parent_field_descriptor->message_type()->FindFieldByName("value");
-
-  if (self->key_field_descriptor == NULL ||
-      self->value_field_descriptor == NULL) {
-    return PyErr_Format(PyExc_KeyError,
-                        "Map entry descriptor did not have key/value fields");
-  }
-
-  return obj.release();
-}
-
-// Initializes the underlying Message object of "to" so it becomes a new parent
-// repeated scalar, and copies all the values from "from" to it. A child scalar
-// container can be released by passing it as both from and to (e.g. making it
-// the recipient of the new parent message and copying the values from itself).
-static int InitializeAndCopyToParentContainer(
-    ScalarMapContainer* from,
-    ScalarMapContainer* to) {
-  // For now we require from == to, re-evaluate if we want to support deep copy
-  // as in repeated_scalar_container.cc.
-  GOOGLE_DCHECK(from == to);
-  Message* old_message = from->message;
-  Message* new_message = old_message->New();
-  to->parent = NULL;
-  to->parent_field_descriptor = from->parent_field_descriptor;
-  to->message = new_message;
-  to->owner.reset(new_message);
-
-  vector<const FieldDescriptor*> fields;
-  fields.push_back(from->parent_field_descriptor);
-  old_message->GetReflection()->SwapFields(old_message, new_message, fields);
-  return 0;
-}
-
-int Release(ScalarMapContainer* self) {
-  return InitializeAndCopyToParentContainer(self, self);
-}
-
-void SetOwner(ScalarMapContainer* self,
-              const shared_ptr<Message>& new_owner) {
-  self->owner = new_owner;
-}
-
-Py_ssize_t Length(PyObject* _self) {
-  ScalarMapContainer* self = GetMap(_self);
-  google::protobuf::Message* message = self->message;
-  return message->GetReflection()->FieldSize(*message,
-                                             self->parent_field_descriptor);
-}
-
-int MapKeyMatches(ScalarMapContainer* self, const Message* entry,
-                  PyObject* key) {
-  // TODO(haberman): do we need more strict type checking?
-  ScopedPyObjectPtr entry_key(
-      cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-  int ret = PyObject_RichCompareBool(key, entry_key.get(), Py_EQ);
-  return ret;
-}
-
-PyObject* GetItem(PyObject* _self, PyObject* key) {
-  ScalarMapContainer* self = GetMap(_self);
-
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  size_t size = reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = size - 1; i >= 0; i--) {
-    const Message& entry = reflection->GetRepeatedMessage(
-        *message, self->parent_field_descriptor, i);
-    int matches = MapKeyMatches(self, &entry, key);
-    if (matches < 0) return NULL;
-    if (matches) {
-      return cmessage::InternalGetScalar(&entry, self->value_field_descriptor);
-    }
-  }
-
-  // Need to add a new entry.
-  Message* entry =
-      reflection->AddMessage(message, self->parent_field_descriptor);
-  PyObject* ret = NULL;
-
-  if (cmessage::InternalSetNonOneofScalar(entry, self->key_field_descriptor,
-                                          key) >= 0) {
-    ret = cmessage::InternalGetScalar(entry, self->value_field_descriptor);
-  }
-
-  self->version++;
-
-  // If there was a type error above, it set the Python exception.
-  return ret;
-}
-
-int SetItem(PyObject *_self, PyObject *key, PyObject *v) {
-  ScalarMapContainer* self = GetMap(_self);
-  cmessage::AssureWritable(self->parent);
-
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-  size_t size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-  self->version++;
-
-  if (v) {
-    // Set item.
-    //
-    // Right now the Reflection API doesn't support map lookup, so we implement
-    // it via linear search.
-    //
-    // TODO(haberman): add lookup API to Reflection API.
-    for (int i = size - 1; i >= 0; i--) {
-      Message* entry = reflection->MutableRepeatedMessage(
-          message, self->parent_field_descriptor, i);
-      int matches = MapKeyMatches(self, entry, key);
-      if (matches < 0) return -1;
-      if (matches) {
-        return cmessage::InternalSetNonOneofScalar(
-            entry, self->value_field_descriptor, v);
-      }
-    }
-
-    // Key is not already present; insert a new entry.
-    Message* entry =
-        reflection->AddMessage(message, self->parent_field_descriptor);
-
-    if (cmessage::InternalSetNonOneofScalar(entry, self->key_field_descriptor,
-                                            key) < 0 ||
-        cmessage::InternalSetNonOneofScalar(entry, self->value_field_descriptor,
-                                            v) < 0) {
-      reflection->RemoveLast(message, self->parent_field_descriptor);
-      return -1;
-    }
-
-    return 0;
-  } else {
-    bool found = false;
-    for (int i = size - 1; i >= 0; i--) {
-      Message* entry = reflection->MutableRepeatedMessage(
-          message, self->parent_field_descriptor, i);
-      int matches = MapKeyMatches(self, entry, key);
-      if (matches < 0) return -1;
-      if (matches) {
-        found = true;
-        if (i != (int)size - 1) {
-          reflection->SwapElements(message, self->parent_field_descriptor, i,
-                                   size - 1);
-        }
-        reflection->RemoveLast(message, self->parent_field_descriptor);
-
-        // Can't exit now, the repeated field representation of maps allows
-        // duplicate keys, and we have to be sure to remove all of them.
-      }
-    }
-
-    if (found) {
-      return 0;
-    } else {
-      PyErr_Format(PyExc_KeyError, "Key not present in map");
-      return -1;
-    }
-  }
-}
-
-PyObject* GetIterator(PyObject *_self) {
-  ScalarMapContainer* self = GetMap(_self);
-
-  ScopedPyObjectPtr obj(PyType_GenericAlloc(&ScalarMapIterator_Type, 0));
-  if (obj == NULL) {
-    return PyErr_Format(PyExc_KeyError, "Could not allocate iterator");
-  }
-
-  ScalarMapIterator* iter = GetIter(obj.get());
-
-  Py_INCREF(self);
-  iter->container = self;
-  iter->version = self->version;
-  iter->dict = PyDict_New();
-  if (iter->dict == NULL) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Could not allocate dict for iterator.");
-  }
-
-  // Build the entire map into a dict right now.  Start from the beginning so
-  // that later entries win in the case of duplicates.
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.  We need to search from the end because the underlying
-  // representation can have duplicates if a user calls MergeFrom(); the last
-  // one needs to win.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  size_t size =
-      reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (size_t i = 0; i < size; i++) {
-    Message* entry = reflection->MutableRepeatedMessage(
-        message, self->parent_field_descriptor, i);
-    ScopedPyObjectPtr key(
-        cmessage::InternalGetScalar(entry, self->key_field_descriptor));
-    ScopedPyObjectPtr val(
-        cmessage::InternalGetScalar(entry, self->value_field_descriptor));
-    if (PyDict_SetItem(iter->dict, key.get(), val.get()) < 0) {
-      return PyErr_Format(PyExc_RuntimeError,
-                          "SetItem failed in iterator construction.");
-    }
-  }
-
-
-  iter->iter = PyObject_GetIter(iter->dict);
-
-
-  return obj.release();
-}
-
-PyObject* Clear(PyObject* _self) {
-  ScalarMapContainer* self = GetMap(_self);
-  cmessage::AssureWritable(self->parent);
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  reflection->ClearField(message, self->parent_field_descriptor);
-
-  Py_RETURN_NONE;
-}
-
-PyObject* Contains(PyObject* _self, PyObject* key) {
-  ScalarMapContainer* self = GetMap(_self);
-
-  Message* message = self->message;
-  const Reflection* reflection = message->GetReflection();
-
-  // Right now the Reflection API doesn't support map lookup, so we implement it
-  // via linear search.
-  //
-  // TODO(haberman): add lookup API to Reflection API.
-  size_t size = reflection->FieldSize(*message, self->parent_field_descriptor);
-  for (int i = size - 1; i >= 0; i--) {
-    const Message& entry = reflection->GetRepeatedMessage(
-        *message, self->parent_field_descriptor, i);
-    int matches = MapKeyMatches(self, &entry, key);
-    if (matches < 0) return NULL;
-    if (matches) {
-      Py_RETURN_TRUE;
-    }
-  }
-
-  Py_RETURN_FALSE;
-}
-
-PyObject* Get(PyObject* self, PyObject* args) {
-  PyObject* key;
-  PyObject* default_value = NULL;
-  if (PyArg_ParseTuple(args, "O|O", &key, &default_value) < 0) {
-    return NULL;
-  }
-
-  ScopedPyObjectPtr is_present(Contains(self, key));
-  if (is_present.get() == NULL) {
-    return NULL;
-  }
-
-  if (PyObject_IsTrue(is_present.get())) {
-    return GetItem(self, key);
-  } else {
-    if (default_value != NULL) {
-      Py_INCREF(default_value);
-      return default_value;
-    } else {
-      Py_RETURN_NONE;
-    }
-  }
-}
-
-static void Dealloc(PyObject* _self) {
-  ScalarMapContainer* self = GetMap(_self);
-  self->owner.reset();
-  Py_TYPE(_self)->tp_free(_self);
-}
-
-static PyMethodDef Methods[] = {
-  { "__contains__", Contains, METH_O,
-    "Tests whether a key is a member of the map." },
-  { "clear", (PyCFunction)Clear, METH_NOARGS,
-    "Removes all elements from the map." },
-  { "get", Get, METH_VARARGS,
-    "Gets the value for the given key if present, or otherwise a default" },
-  /*
-  { "__deepcopy__", (PyCFunction)DeepCopy, METH_VARARGS,
-    "Makes a deep copy of the class." },
-  { "__reduce__", (PyCFunction)Reduce, METH_NOARGS,
-    "Outputs picklable representation of the repeated field." },
-  */
-  {NULL, NULL},
-};
-
-}  // namespace scalar_map_container
-
-namespace scalar_map_iterator {
-
-static void Dealloc(PyObject* _self) {
-  ScalarMapIterator* self = GetIter(_self);
-  Py_DECREF(self->dict);
-  Py_DECREF(self->iter);
-  Py_DECREF(self->container);
-  Py_TYPE(_self)->tp_free(_self);
-}
-
-PyObject* IterNext(PyObject* _self) {
-  ScalarMapIterator* self = GetIter(_self);
-
-  // This won't catch mutations to the map performed by MergeFrom(); no easy way
-  // to address that.
-  if (self->version != self->container->version) {
-    return PyErr_Format(PyExc_RuntimeError,
-                        "Map modified during iteration.");
-  }
-
-  return PyIter_Next(self->iter);
-}
-
-}  // namespace scalar_map_iterator
-
- 
-#if PY_MAJOR_VERSION >= 3
-  static PyType_Slot ScalarMapContainer_Type_slots[] = {
-      {Py_tp_dealloc, (void *)scalar_map_container::Dealloc},
-      {Py_mp_length, (void *)scalar_map_container::Length},
-      {Py_mp_subscript, (void *)scalar_map_container::GetItem},
-      {Py_mp_ass_subscript, (void *)scalar_map_container::SetItem},
-      {Py_tp_methods, (void *)scalar_map_container::Methods},
-      {Py_tp_iter, (void *)scalar_map_container::GetIterator},
-      {0, 0},
-  };
-
-  PyType_Spec ScalarMapContainer_Type_spec = {
-      FULL_MODULE_NAME ".ScalarMapContainer",
-      sizeof(ScalarMapContainer),
-      0,
-      Py_TPFLAGS_DEFAULT,
-      ScalarMapContainer_Type_slots
-  };
-  PyObject *ScalarMapContainer_Type;
-#else
-  static PyMappingMethods MpMethods = {
-    scalar_map_container::Length,    // mp_length
-    scalar_map_container::GetItem,   // mp_subscript
-    scalar_map_container::SetItem,   // mp_ass_subscript
-  };
-
-  PyTypeObject ScalarMapContainer_Type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
-    FULL_MODULE_NAME ".ScalarMapContainer",  //  tp_name
-    sizeof(ScalarMapContainer),          //  tp_basicsize
-    0,                                   //  tp_itemsize
-    scalar_map_container::Dealloc,       //  tp_dealloc
-    0,                                   //  tp_print
-    0,                                   //  tp_getattr
-    0,                                   //  tp_setattr
-    0,                                   //  tp_compare
-    0,                                   //  tp_repr
-    0,                                   //  tp_as_number
-    0,                                   //  tp_as_sequence
-    &MpMethods,                          //  tp_as_mapping
-    0,                                   //  tp_hash
-    0,                                   //  tp_call
-    0,                                   //  tp_str
-    0,                                   //  tp_getattro
-    0,                                   //  tp_setattro
-    0,                                   //  tp_as_buffer
-    Py_TPFLAGS_DEFAULT,                  //  tp_flags
-    "A scalar map container",            //  tp_doc
-    0,                                   //  tp_traverse
-    0,                                   //  tp_clear
-    0,                                   //  tp_richcompare
-    0,                                   //  tp_weaklistoffset
-    scalar_map_container::GetIterator,   //  tp_iter
-    0,                                   //  tp_iternext
-    scalar_map_container::Methods,       //  tp_methods
-    0,                                   //  tp_members
-    0,                                   //  tp_getset
-    0,                                   //  tp_base
-    0,                                   //  tp_dict
-    0,                                   //  tp_descr_get
-    0,                                   //  tp_descr_set
-    0,                                   //  tp_dictoffset
-    0,                                   //  tp_init
-  };
-#endif
-
-PyTypeObject ScalarMapIterator_Type = {
-  PyVarObject_HEAD_INIT(&PyType_Type, 0)
-  FULL_MODULE_NAME ".ScalarMapIterator",  //  tp_name
-  sizeof(ScalarMapIterator),           //  tp_basicsize
-  0,                                   //  tp_itemsize
-  scalar_map_iterator::Dealloc,        //  tp_dealloc
-  0,                                   //  tp_print
-  0,                                   //  tp_getattr
-  0,                                   //  tp_setattr
-  0,                                   //  tp_compare
-  0,                                   //  tp_repr
-  0,                                   //  tp_as_number
-  0,                                   //  tp_as_sequence
-  0,                                   //  tp_as_mapping
-  0,                                   //  tp_hash
-  0,                                   //  tp_call
-  0,                                   //  tp_str
-  0,                                   //  tp_getattro
-  0,                                   //  tp_setattro
-  0,                                   //  tp_as_buffer
-  Py_TPFLAGS_DEFAULT,                  //  tp_flags
-  "A scalar map iterator",             //  tp_doc
-  0,                                   //  tp_traverse
-  0,                                   //  tp_clear
-  0,                                   //  tp_richcompare
-  0,                                   //  tp_weaklistoffset
-  PyObject_SelfIter,                   //  tp_iter
-  scalar_map_iterator::IterNext,       //  tp_iternext
-  0,                                   //  tp_methods
-  0,                                   //  tp_members
-  0,                                   //  tp_getset
-  0,                                   //  tp_base
-  0,                                   //  tp_dict
-  0,                                   //  tp_descr_get
-  0,                                   //  tp_descr_set
-  0,                                   //  tp_dictoffset
-  0,                                   //  tp_init
-};
-
-}  // namespace python
-}  // namespace protobuf
-}  // namespace google
diff --git a/python/google/protobuf/pyext/scalar_map_container.h b/python/google/protobuf/pyext/scalar_map_container.h
deleted file mode 100644
index 4d663b88..00000000
--- a/python/google/protobuf/pyext/scalar_map_container.h
+++ /dev/null
@@ -1,119 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_SCALAR_MAP_CONTAINER_H__
-#define GOOGLE_PROTOBUF_PYTHON_CPP_SCALAR_MAP_CONTAINER_H__
-
-#include <Python.h>
-
-#include <memory>
-#ifndef _SHARED_PTR_H
-#include <google/protobuf/stubs/shared_ptr.h>
-#endif
-
-#include <google/protobuf/descriptor.h>
-
-namespace google {
-namespace protobuf {
-
-class Message;
-
-#ifdef _SHARED_PTR_H
-using std::shared_ptr;
-#else
-using internal::shared_ptr;
-#endif
-
-namespace python {
-
-struct CMessage;
-
-struct ScalarMapContainer {
-  PyObject_HEAD;
-
-  // This is the top-level C++ Message object that owns the whole
-  // proto tree.  Every Python ScalarMapContainer holds a
-  // reference to it in order to keep it alive as long as there's a
-  // Python object that references any part of the tree.
-  shared_ptr<Message> owner;
-
-  // Pointer to the C++ Message that contains this container.  The
-  // ScalarMapContainer does not own this pointer.
-  Message* message;
-
-  // Weak reference to a parent CMessage object (i.e. may be NULL.)
-  //
-  // Used to make sure all ancestors are also mutable when first
-  // modifying the container.
-  CMessage* parent;
-
-  // Pointer to the parent's descriptor that describes this
-  // field.  Used together with the parent's message when making a
-  // default message instance mutable.
-  // The pointer is owned by the global DescriptorPool.
-  const FieldDescriptor* parent_field_descriptor;
-  const FieldDescriptor* key_field_descriptor;
-  const FieldDescriptor* value_field_descriptor;
-
-  // We bump this whenever we perform a mutation, to invalidate existing
-  // iterators.
-  uint64 version;
-};
-
-#if PY_MAJOR_VERSION >= 3
-  extern PyObject *ScalarMapContainer_Type;
-  extern PyType_Spec ScalarMapContainer_Type_spec;
-#else
-  extern PyTypeObject ScalarMapContainer_Type;
-#endif
-extern PyTypeObject ScalarMapIterator_Type;
-
-namespace scalar_map_container {
-
-// Builds a ScalarMapContainer object, from a parent message and a
-// field descriptor.
-extern PyObject *NewContainer(
-    CMessage* parent, const FieldDescriptor* parent_field_descriptor);
-
-// Releases the messages in the container to a new message.
-//
-// Returns 0 on success, -1 on failure.
-int Release(ScalarMapContainer* self);
-
-// Set the owner field of self and any children of self.
-void SetOwner(ScalarMapContainer* self,
-              const shared_ptr<Message>& new_owner);
-
-}  // namespace scalar_map_container
-}  // namespace python
-}  // namespace protobuf
-
-}  // namespace google
-#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_SCALAR_MAP_CONTAINER_H__
diff --git a/python/google/protobuf/symbol_database.py b/python/google/protobuf/symbol_database.py
index b81ef4d7..87760f26 100644
--- a/python/google/protobuf/symbol_database.py
+++ b/python/google/protobuf/symbol_database.py
@@ -60,7 +60,6 @@ Example usage:
 """
 
 
-from google.protobuf import descriptor as _descriptor
 from google.protobuf import descriptor_pool
 
 
@@ -73,37 +72,12 @@ class SymbolDatabase(object):
   buffer types used within a program.
   """
 
-  # pylint: disable=protected-access
-  if _descriptor._USE_C_DESCRIPTORS:
-
-    def __new__(cls):
-      raise TypeError("Instances of SymbolDatabase cannot be created")
-
-    @classmethod
-    def _CreateDefaultDatabase(cls):
-      self = object.__new__(cls)  # Bypass the __new__ above.
-      # Don't call __init__() and initialize here.
-      self._symbols = {}
-      self._symbols_by_file = {}
-      # As of today all descriptors are registered and retrieved from
-      # _message.default_pool (see FileDescriptor.__new__), so it's not
-      # necessary to use another pool.
-      self.pool = _descriptor._message.default_pool
-      return self
-  # pylint: enable=protected-access
-
-  else:
-
-    @classmethod
-    def _CreateDefaultDatabase(cls):
-      return cls()
-
-  def __init__(self):
+  def __init__(self, pool=None):
     """Constructor."""
 
     self._symbols = {}
     self._symbols_by_file = {}
-    self.pool = descriptor_pool.DescriptorPool()
+    self.pool = pool or descriptor_pool.Default()
 
   def RegisterMessage(self, message):
     """Registers the given message type in the local database.
@@ -203,7 +177,7 @@ class SymbolDatabase(object):
       result.update(self._symbols_by_file[f])
     return result
 
-_DEFAULT = SymbolDatabase._CreateDefaultDatabase()
+_DEFAULT = SymbolDatabase(pool=descriptor_pool.Default())
 
 
 def Default():
diff --git a/python/google/protobuf/text_format.py b/python/google/protobuf/text_format.py
index e4fadf09..8d256076 100755
--- a/python/google/protobuf/text_format.py
+++ b/python/google/protobuf/text_format.py
@@ -66,6 +66,7 @@ _FLOAT_INFINITY = re.compile('-?inf(?:inity)?f?', re.IGNORECASE)
 _FLOAT_NAN = re.compile('nanf?', re.IGNORECASE)
 _FLOAT_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_FLOAT,
                           descriptor.FieldDescriptor.CPPTYPE_DOUBLE])
+_QUOTES = frozenset(("'", '"'))
 
 
 class Error(Exception):
@@ -73,7 +74,8 @@ class Error(Exception):
 
 
 class ParseError(Error):
-  """Thrown in case of ASCII parsing error."""
+  """Thrown in case of text parsing error."""
+
 
 class TextWriter(object):
   def __init__(self, as_utf8):
@@ -102,7 +104,8 @@ def MessageToString(message, as_utf8=False, as_one_line=False,
 
   Floating point values can be formatted compactly with 15 digits of
   precision (which is the most that IEEE 754 "double" can guarantee)
-  using float_format='.15g'.
+  using float_format='.15g'. To ensure that converting to text and back to a
+  proto will result in an identical value, float_format='.17g' should be used.
 
   Args:
     message: The protocol buffers message.
@@ -130,11 +133,13 @@ def MessageToString(message, as_utf8=False, as_one_line=False,
     return result.rstrip()
   return result
 
+
 def _IsMapEntry(field):
   return (field.type == descriptor.FieldDescriptor.TYPE_MESSAGE and
           field.message_type.has_options and
           field.message_type.GetOptions().map_entry)
 
+
 def PrintMessage(message, out, indent=0, as_utf8=False, as_one_line=False,
                  pointy_brackets=False, use_index_order=False,
                  float_format=None):
@@ -166,17 +171,18 @@ def PrintMessage(message, out, indent=0, as_utf8=False, as_one_line=False,
                  use_index_order=use_index_order,
                  float_format=float_format)
 
+
 def PrintField(field, value, out, indent=0, as_utf8=False, as_one_line=False,
                pointy_brackets=False, use_index_order=False, float_format=None):
   """Print a single field name/value pair.  For repeated fields, the value
-  should be a single element."""
+  should be a single element.
+  """
 
   out.write(' ' * indent)
   if field.is_extension:
     out.write('[')
     if (field.containing_type.GetOptions().message_set_wire_format and
         field.type == descriptor.FieldDescriptor.TYPE_MESSAGE and
-        field.message_type == field.extension_scope and
         field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL):
       out.write(field.message_type.full_name)
     else:
@@ -262,95 +268,113 @@ def PrintFieldValue(field, value, out, indent=0, as_utf8=False,
     out.write(str(value))
 
 
-def Parse(text, message):
-  """Parses an ASCII representation of a protocol message into a message.
+def Parse(text, message, allow_unknown_extension=False):
+  """Parses an text representation of a protocol message into a message.
 
   Args:
-    text: Message ASCII representation.
+    text: Message text representation.
     message: A protocol buffer message to merge into.
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Returns:
     The same message passed as argument.
 
   Raises:
-    ParseError: On ASCII parsing problems.
+    ParseError: On text parsing problems.
   """
-  if not isinstance(text, str): text = text.decode('utf-8')
-  return ParseLines(text.split('\n'), message)
+  if not isinstance(text, str):
+    text = text.decode('utf-8')
+  return ParseLines(text.split('\n'), message, allow_unknown_extension)
 
 
-def Merge(text, message):
-  """Parses an ASCII representation of a protocol message into a message.
+def Merge(text, message, allow_unknown_extension=False):
+  """Parses an text representation of a protocol message into a message.
 
   Like Parse(), but allows repeated values for a non-repeated field, and uses
   the last one.
 
   Args:
-    text: Message ASCII representation.
+    text: Message text representation.
     message: A protocol buffer message to merge into.
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Returns:
     The same message passed as argument.
 
   Raises:
-    ParseError: On ASCII parsing problems.
+    ParseError: On text parsing problems.
   """
-  return MergeLines(text.split('\n'), message)
+  return MergeLines(text.split('\n'), message, allow_unknown_extension)
 
 
-def ParseLines(lines, message):
-  """Parses an ASCII representation of a protocol message into a message.
+def ParseLines(lines, message, allow_unknown_extension=False):
+  """Parses an text representation of a protocol message into a message.
 
   Args:
-    lines: An iterable of lines of a message's ASCII representation.
+    lines: An iterable of lines of a message's text representation.
     message: A protocol buffer message to merge into.
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Returns:
     The same message passed as argument.
 
   Raises:
-    ParseError: On ASCII parsing problems.
+    ParseError: On text parsing problems.
   """
-  _ParseOrMerge(lines, message, False)
+  _ParseOrMerge(lines, message, False, allow_unknown_extension)
   return message
 
 
-def MergeLines(lines, message):
-  """Parses an ASCII representation of a protocol message into a message.
+def MergeLines(lines, message, allow_unknown_extension=False):
+  """Parses an text representation of a protocol message into a message.
 
   Args:
-    lines: An iterable of lines of a message's ASCII representation.
+    lines: An iterable of lines of a message's text representation.
     message: A protocol buffer message to merge into.
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Returns:
     The same message passed as argument.
 
   Raises:
-    ParseError: On ASCII parsing problems.
+    ParseError: On text parsing problems.
   """
-  _ParseOrMerge(lines, message, True)
+  _ParseOrMerge(lines, message, True, allow_unknown_extension)
   return message
 
 
-def _ParseOrMerge(lines, message, allow_multiple_scalars):
-  """Converts an ASCII representation of a protocol message into a message.
+def _ParseOrMerge(lines,
+                  message,
+                  allow_multiple_scalars,
+                  allow_unknown_extension=False):
+  """Converts an text representation of a protocol message into a message.
 
   Args:
-    lines: Lines of a message's ASCII representation.
+    lines: Lines of a message's text representation.
     message: A protocol buffer message to merge into.
     allow_multiple_scalars: Determines if repeated values for a non-repeated
       field are permitted, e.g., the string "foo: 1 foo: 2" for a
       required/optional field named "foo".
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Raises:
-    ParseError: On ASCII parsing problems.
+    ParseError: On text parsing problems.
   """
   tokenizer = _Tokenizer(lines)
   while not tokenizer.AtEnd():
-    _MergeField(tokenizer, message, allow_multiple_scalars)
+    _MergeField(tokenizer, message, allow_multiple_scalars,
+                allow_unknown_extension)
 
 
-def _MergeField(tokenizer, message, allow_multiple_scalars):
+def _MergeField(tokenizer,
+                message,
+                allow_multiple_scalars,
+                allow_unknown_extension=False):
   """Merges a single protocol message field into a message.
 
   Args:
@@ -359,9 +383,11 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
     allow_multiple_scalars: Determines if repeated values for a non-repeated
       field are permitted, e.g., the string "foo: 1 foo: 2" for a
       required/optional field named "foo".
+    allow_unknown_extension: if True, skip over missing extensions and keep
+      parsing
 
   Raises:
-    ParseError: In case of ASCII parsing problems.
+    ParseError: In case of text parsing problems.
   """
   message_descriptor = message.DESCRIPTOR
   if (hasattr(message_descriptor, 'syntax') and
@@ -383,13 +409,18 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
     field = message.Extensions._FindExtensionByName(name)
     # pylint: enable=protected-access
     if not field:
-      raise tokenizer.ParseErrorPreviousToken(
-          'Extension "%s" not registered.' % name)
+      if allow_unknown_extension:
+        field = None
+      else:
+        raise tokenizer.ParseErrorPreviousToken(
+            'Extension "%s" not registered.' % name)
     elif message_descriptor != field.containing_type:
       raise tokenizer.ParseErrorPreviousToken(
           'Extension "%s" does not extend message type "%s".' % (
               name, message_descriptor.full_name))
+
     tokenizer.Consume(']')
+
   else:
     name = tokenizer.ConsumeIdentifier()
     field = message_descriptor.fields_by_name.get(name, None)
@@ -411,7 +442,7 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
           'Message type "%s" has no field named "%s".' % (
               message_descriptor.full_name, name))
 
-  if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+  if field and field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
     is_map_entry = _IsMapEntry(field)
     tokenizer.TryConsume(':')
 
@@ -438,7 +469,8 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
     while not tokenizer.TryConsume(end_token):
       if tokenizer.AtEnd():
         raise tokenizer.ParseErrorPreviousToken('Expected "%s".' % (end_token))
-      _MergeField(tokenizer, sub_message, allow_multiple_scalars)
+      _MergeField(tokenizer, sub_message, allow_multiple_scalars,
+                  allow_unknown_extension)
 
     if is_map_entry:
       value_cpptype = field.message_type.fields_by_name['value'].cpp_type
@@ -447,8 +479,63 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
         value.MergeFrom(sub_message.value)
       else:
         getattr(message, field.name)[sub_message.key] = sub_message.value
+  elif field:
+    tokenizer.Consume(':')
+    if (field.label == descriptor.FieldDescriptor.LABEL_REPEATED and
+        tokenizer.TryConsume('[')):
+      # Short repeated format, e.g. "foo: [1, 2, 3]"
+      while True:
+        _MergeScalarField(tokenizer, message, field, allow_multiple_scalars)
+        if tokenizer.TryConsume(']'):
+          break
+        tokenizer.Consume(',')
+    else:
+      _MergeScalarField(tokenizer, message, field, allow_multiple_scalars)
+  else:  # Proto field is unknown.
+    assert allow_unknown_extension
+    _SkipFieldContents(tokenizer)
+
+  # For historical reasons, fields may optionally be separated by commas or
+  # semicolons.
+  if not tokenizer.TryConsume(','):
+    tokenizer.TryConsume(';')
+
+
+def _SkipFieldContents(tokenizer):
+  """Skips over contents (value or message) of a field.
+
+  Args:
+    tokenizer: A tokenizer to parse the field name and values.
+  """
+  # Try to guess the type of this field.
+  # If this field is not a message, there should be a ":" between the
+  # field name and the field value and also the field value should not
+  # start with "{" or "<" which indicates the beginning of a message body.
+  # If there is no ":" or there is a "{" or "<" after ":", this field has
+  # to be a message or the input is ill-formed.
+  if tokenizer.TryConsume(':') and not tokenizer.LookingAt(
+      '{') and not tokenizer.LookingAt('<'):
+    _SkipFieldValue(tokenizer)
+  else:
+    _SkipFieldMessage(tokenizer)
+
+
+def _SkipField(tokenizer):
+  """Skips over a complete field (name and value/message).
+
+  Args:
+    tokenizer: A tokenizer to parse the field name and values.
+  """
+  if tokenizer.TryConsume('['):
+    # Consume extension name.
+    tokenizer.ConsumeIdentifier()
+    while tokenizer.TryConsume('.'):
+      tokenizer.ConsumeIdentifier()
+    tokenizer.Consume(']')
   else:
-    _MergeScalarField(tokenizer, message, field, allow_multiple_scalars)
+    tokenizer.ConsumeIdentifier()
+
+  _SkipFieldContents(tokenizer)
 
   # For historical reasons, fields may optionally be separated by commas or
   # semicolons.
@@ -456,6 +543,48 @@ def _MergeField(tokenizer, message, allow_multiple_scalars):
     tokenizer.TryConsume(';')
 
 
+def _SkipFieldMessage(tokenizer):
+  """Skips over a field message.
+
+  Args:
+    tokenizer: A tokenizer to parse the field name and values.
+  """
+
+  if tokenizer.TryConsume('<'):
+    delimiter = '>'
+  else:
+    tokenizer.Consume('{')
+    delimiter = '}'
+
+  while not tokenizer.LookingAt('>') and not tokenizer.LookingAt('}'):
+    _SkipField(tokenizer)
+
+  tokenizer.Consume(delimiter)
+
+
+def _SkipFieldValue(tokenizer):
+  """Skips over a field value.
+
+  Args:
+    tokenizer: A tokenizer to parse the field name and values.
+
+  Raises:
+    ParseError: In case an invalid field value is found.
+  """
+  # String tokens can come in multiple adjacent string literals.
+  # If we can consume one, consume as many as we can.
+  if tokenizer.TryConsumeString():
+    while tokenizer.TryConsumeString():
+      pass
+    return
+
+  if (not tokenizer.TryConsumeIdentifier() and
+      not tokenizer.TryConsumeInt64() and
+      not tokenizer.TryConsumeUint64() and
+      not tokenizer.TryConsumeFloat()):
+    raise ParseError('Invalid field value: ' + tokenizer.token)
+
+
 def _MergeScalarField(tokenizer, message, field, allow_multiple_scalars):
   """Merges a single protocol message scalar field into a message.
 
@@ -468,10 +597,9 @@ def _MergeScalarField(tokenizer, message, field, allow_multiple_scalars):
       required/optional field named "foo".
 
   Raises:
-    ParseError: In case of ASCII parsing problems.
+    ParseError: In case of text parsing problems.
     RuntimeError: On runtime errors.
   """
-  tokenizer.Consume(':')
   value = None
 
   if field.type in (descriptor.FieldDescriptor.TYPE_INT32,
@@ -525,7 +653,7 @@ def _MergeScalarField(tokenizer, message, field, allow_multiple_scalars):
 
 
 class _Tokenizer(object):
-  """Protocol buffer ASCII representation tokenizer.
+  """Protocol buffer text representation tokenizer.
 
   This class handles the lower level string parsing by splitting it into
   meaningful tokens.
@@ -534,11 +662,13 @@ class _Tokenizer(object):
   """
 
   _WHITESPACE = re.compile('(\\s|(#.*$))+', re.MULTILINE)
-  _TOKEN = re.compile(
-      '[a-zA-Z_][0-9a-zA-Z_+-]*|'           # an identifier
-      '[0-9+-][0-9a-zA-Z_.+-]*|'            # a number
-      '\"([^\"\n\\\\]|\\\\.)*(\"|\\\\?$)|'  # a double-quoted string
-      '\'([^\'\n\\\\]|\\\\.)*(\'|\\\\?$)')  # a single-quoted string
+  _TOKEN = re.compile('|'.join([
+      r'[a-zA-Z_][0-9a-zA-Z_+-]*',             # an identifier
+      r'([0-9+-]|(\.[0-9]))[0-9a-zA-Z_.+-]*',  # a number
+  ] + [                                        # quoted str for each quote mark
+      r'{qt}([^{qt}\n\\]|\\.)*({qt}|\\?$)'.format(qt=mark) for mark in _QUOTES
+  ]))
+
   _IDENTIFIER = re.compile(r'\w+')
 
   def __init__(self, lines):
@@ -555,6 +685,9 @@ class _Tokenizer(object):
     self._SkipWhitespace()
     self.NextToken()
 
+  def LookingAt(self, token):
+    return self.token == token
+
   def AtEnd(self):
     """Checks the end of the text was reached.
 
@@ -610,6 +743,13 @@ class _Tokenizer(object):
     if not self.TryConsume(token):
       raise self._ParseError('Expected "%s".' % token)
 
+  def TryConsumeIdentifier(self):
+    try:
+      self.ConsumeIdentifier()
+      return True
+    except ParseError:
+      return False
+
   def ConsumeIdentifier(self):
     """Consumes protocol message field identifier.
 
@@ -657,6 +797,13 @@ class _Tokenizer(object):
     self.NextToken()
     return result
 
+  def TryConsumeInt64(self):
+    try:
+      self.ConsumeInt64()
+      return True
+    except ParseError:
+      return False
+
   def ConsumeInt64(self):
     """Consumes a signed 64bit integer number.
 
@@ -673,6 +820,13 @@ class _Tokenizer(object):
     self.NextToken()
     return result
 
+  def TryConsumeUint64(self):
+    try:
+      self.ConsumeUint64()
+      return True
+    except ParseError:
+      return False
+
   def ConsumeUint64(self):
     """Consumes an unsigned 64bit integer number.
 
@@ -689,6 +843,13 @@ class _Tokenizer(object):
     self.NextToken()
     return result
 
+  def TryConsumeFloat(self):
+    try:
+      self.ConsumeFloat()
+      return True
+    except ParseError:
+      return False
+
   def ConsumeFloat(self):
     """Consumes an floating point number.
 
@@ -721,6 +882,13 @@ class _Tokenizer(object):
     self.NextToken()
     return result
 
+  def TryConsumeString(self):
+    try:
+      self.ConsumeString()
+      return True
+    except ParseError:
+      return False
+
   def ConsumeString(self):
     """Consumes a string value.
 
@@ -746,7 +914,7 @@ class _Tokenizer(object):
       ParseError: If a byte array value couldn't be consumed.
     """
     the_list = [self._ConsumeSingleByteString()]
-    while self.token and self.token[0] in ('\'', '"'):
+    while self.token and self.token[0] in _QUOTES:
       the_list.append(self._ConsumeSingleByteString())
     return b''.join(the_list)
 
@@ -757,11 +925,13 @@ class _Tokenizer(object):
     tokens which are automatically concatenated, like in C or Python.  This
     method only consumes one token.
 
+    Returns:
+      The token parsed.
     Raises:
       ParseError: When the wrong format data is found.
     """
     text = self.token
-    if len(text) < 1 or text[0] not in ('\'', '"'):
+    if len(text) < 1 or text[0] not in _QUOTES:
       raise self._ParseError('Expected string but found: %r' % (text,))
 
     if len(text) < 2 or text[-1] != text[0]:
diff --git a/python/setup.py b/python/setup.py
index 18865e03..22f6e816 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -89,6 +89,7 @@ def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/unittest_no_generic_services.proto", False)
   generate_proto("../src/google/protobuf/unittest_proto3_arena.proto", False)
   generate_proto("../src/google/protobuf/util/json_format_proto3.proto", False)
+  generate_proto("google/protobuf/internal/any_test.proto", False)
   generate_proto("google/protobuf/internal/descriptor_pool_test1.proto", False)
   generate_proto("google/protobuf/internal/descriptor_pool_test2.proto", False)
   generate_proto("google/protobuf/internal/factory_test1.proto", False)
diff --git a/src/Makefile.am b/src/Makefile.am
index b7d64093..d684c937 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -148,15 +148,16 @@ nobase_include_HEADERS =                                        \
   google/protobuf/compiler/plugin.h                             \
   google/protobuf/compiler/plugin.pb.h                          \
   google/protobuf/compiler/cpp/cpp_generator.h                  \
+  google/protobuf/compiler/csharp/csharp_generator.h            \
+  google/protobuf/compiler/csharp/csharp_names.h                \
   google/protobuf/compiler/java/java_generator.h                \
   google/protobuf/compiler/java/java_names.h                    \
   google/protobuf/compiler/javanano/javanano_generator.h        \
+  google/protobuf/compiler/js/js_generator.h                    \
   google/protobuf/compiler/objectivec/objectivec_generator.h    \
   google/protobuf/compiler/objectivec/objectivec_helpers.h      \
   google/protobuf/compiler/python/python_generator.h            \
   google/protobuf/compiler/ruby/ruby_generator.h                \
-  google/protobuf/compiler/csharp/csharp_generator.h            \
-  google/protobuf/compiler/csharp/csharp_names.h                \
   google/protobuf/util/type_resolver.h                          \
   google/protobuf/util/field_comparator.h                       \
   google/protobuf/util/field_mask_util.h                        \
@@ -276,6 +277,8 @@ libprotobuf_la_SOURCES =                                       \
   google/protobuf/util/internal/protostream_objectsource.h     \
   google/protobuf/util/internal/protostream_objectwriter.cc    \
   google/protobuf/util/internal/protostream_objectwriter.h     \
+  google/protobuf/util/internal/proto_writer.cc                \
+  google/protobuf/util/internal/proto_writer.h                 \
   google/protobuf/util/internal/snake2camel_objectwriter.h     \
   google/protobuf/util/internal/structured_objectwriter.h      \
   google/protobuf/util/internal/testdata                       \
@@ -386,6 +389,7 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/java/java_string_field_lite.h       \
   google/protobuf/compiler/java/java_doc_comment.cc            \
   google/protobuf/compiler/java/java_doc_comment.h             \
+  google/protobuf/compiler/js/js_generator.cc                  \
   google/protobuf/compiler/javanano/javanano_enum.cc           \
   google/protobuf/compiler/javanano/javanano_enum.h            \
   google/protobuf/compiler/javanano/javanano_enum_field.cc     \
diff --git a/src/google/protobuf/any.cc b/src/google/protobuf/any.cc
index 7351d377..f3ca06bf 100644
--- a/src/google/protobuf/any.cc
+++ b/src/google/protobuf/any.cc
@@ -65,9 +65,16 @@ bool AnyMetadata::UnpackTo(Message* message) const {
 }
 
 bool AnyMetadata::InternalIs(const Descriptor* descriptor) const {
-  return type_url_->GetNoArena(
-             &::google::protobuf::internal::GetEmptyString()) ==
-         GetTypeUrl(descriptor);
+  const string type_url = type_url_->GetNoArena(
+             &::google::protobuf::internal::GetEmptyString());
+  const string full_name = descriptor->full_name();
+  if (type_url.length() < full_name.length()) {
+      return false;
+  }
+  return (0 == type_url.compare(
+    type_url.length() - full_name.length(),
+    full_name.length(),
+    full_name));
 }
 
 bool ParseAnyTypeUrl(const string& type_url, string* full_type_name) {
diff --git a/src/google/protobuf/any.h b/src/google/protobuf/any.h
index f760ad5d..c8dbef13 100644
--- a/src/google/protobuf/any.h
+++ b/src/google/protobuf/any.h
@@ -75,7 +75,7 @@ extern const char kTypeGoogleProdComPrefix[];  // "type.googleprod.com/".
 // Get the proto type name from Any::type_url value. For example, passing
 // "type.googleapis.com/rpc.QueryOrigin" will return "rpc.QueryOrigin" in
 // *full_type_name. Returns false if type_url does not start with
-// "type.googleapis.com".
+// "type.googleapis.com" or "type.googleprod.com".
 bool ParseAnyTypeUrl(const string& type_url, string* full_type_name);
 
 // See if message is of type google.protobuf.Any, if so, return the descriptors
diff --git a/src/google/protobuf/any.pb.cc b/src/google/protobuf/any.pb.cc
index 321fd315..0bf523b3 100644
--- a/src/google/protobuf/any.pb.cc
+++ b/src/google/protobuf/any.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/any.proto b/src/google/protobuf/any.proto
index 423699be..e8a18bc3 100644
--- a/src/google/protobuf/any.proto
+++ b/src/google/protobuf/any.proto
@@ -27,21 +27,22 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "AnyProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option java_package = "com.google.protobuf";
+option java_outer_classname = "AnyProto";
+option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
-
 // `Any` contains an arbitrary serialized message along with a URL
 // that describes the type of the serialized message.
 //
+//
 // JSON
 // ====
 // The JSON representation of an `Any` value uses the regular
@@ -62,8 +63,8 @@ option objc_class_prefix = "GPB";
 //
 // If the embedded message type is well-known and has a custom JSON
 // representation, that representation will be embedded adding a field
-// `value` which holds the custom JSON in addition to the the `@type`
-// field. Example (for message [google.protobuf.Duration][google.protobuf.Duration]):
+// `value` which holds the custom JSON in addition to the `@type`
+// field. Example (for message [google.protobuf.Duration][]):
 //
 //     {
 //       "@type": "type.googleapis.com/google.protobuf.Duration",
@@ -80,7 +81,7 @@ message Any {
   // * If no schema is provided, `https` is assumed.
   // * The last segment of the URL's path must represent the fully
   //   qualified name of the type (as in `path/google.protobuf.Duration`).
-  // * An HTTP GET on the URL must yield a [google.protobuf.Type][google.protobuf.Type]
+  // * An HTTP GET on the URL must yield a [google.protobuf.Type][]
   //   value in binary format, or produce an error.
   // * Applications are allowed to cache lookup results based on the
   //   URL, or have them precompiled into a binary to avoid any
diff --git a/src/google/protobuf/api.pb.cc b/src/google/protobuf/api.pb.cc
index ed90702c..e589a89d 100644
--- a/src/google/protobuf/api.pb.cc
+++ b/src/google/protobuf/api.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/api.proto b/src/google/protobuf/api.proto
index 597a6497..dbe87b8f 100644
--- a/src/google/protobuf/api.proto
+++ b/src/google/protobuf/api.proto
@@ -27,6 +27,7 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
@@ -34,11 +35,11 @@ package google.protobuf;
 import "google/protobuf/source_context.proto";
 import "google/protobuf/type.proto";
 
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option java_package = "com.google.protobuf";
 option java_outer_classname = "ApiProto";
 option java_multiple_files = true;
 option java_generate_equals_and_hash = true;
-option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 // Api is a light-weight descriptor for a protocol buffer service.
@@ -75,6 +76,7 @@ message Api {
   // be omitted. Zero major versions must only be used for
   // experimental, none-GA apis.
   //
+  //
   string version = 4;
 
   // Source context for the protocol buffer service represented by this
@@ -141,7 +143,6 @@ message Method {
 //
 //     package google.storage.v2;
 //     service Storage {
-//       // (-- see AccessControl.GetAcl --)
 //       rpc GetAcl(GetAclRequest) returns (Acl);
 //
 //       // Get a data record.
diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h
index 40c1e7c2..6a35183e 100644
--- a/src/google/protobuf/arena.h
+++ b/src/google/protobuf/arena.h
@@ -591,14 +591,12 @@ class LIBPROTOBUF_EXPORT Arena {
   // This is inside Arena because only Arena has the friend relationships
   // necessary to see the underlying generated code traits.
   template<typename T>
-  struct is_destructor_skippable :
-      public google::protobuf::internal::integral_constant<bool,
-              sizeof(InternalIsDestructorSkippableHelper::DestructorSkippable<
-                     const T>(static_cast<const T*>(0))) ==
-              sizeof(char) ||
-              google::protobuf::internal::has_trivial_destructor<T>::value> {
-  };
-
+  struct is_destructor_skippable
+      : public google::protobuf::internal::integral_constant<
+            bool,
+            sizeof(InternalIsDestructorSkippableHelper::DestructorSkippable<
+                   const T>(static_cast<const T*>(0))) == sizeof(char) ||
+                google::protobuf::internal::has_trivial_destructor<T>::value> {};
 
   // CreateMessage<T> requires that T supports arenas, but this private method
   // works whether or not T supports arenas. These are not exposed to user code
diff --git a/src/google/protobuf/arenastring.h b/src/google/protobuf/arenastring.h
index 1dacdc68..ef57033b 100755
--- a/src/google/protobuf/arenastring.h
+++ b/src/google/protobuf/arenastring.h
@@ -36,7 +36,6 @@
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/stubs/fastmem.h>
-
 #include <google/protobuf/arena.h>
 #include <google/protobuf/generated_message_util.h>
 
diff --git a/src/google/protobuf/compiler/command_line_interface.cc b/src/google/protobuf/compiler/command_line_interface.cc
index 26a4f0b0..deb3d0f1 100644
--- a/src/google/protobuf/compiler/command_line_interface.cc
+++ b/src/google/protobuf/compiler/command_line_interface.cc
@@ -271,15 +271,35 @@ class CommandLineInterface::ErrorPrinter : public MultiFileErrorCollector,
   // implements MultiFileErrorCollector ------------------------------
   void AddError(const string& filename, int line, int column,
                 const string& message) {
+    AddErrorOrWarning(filename, line, column, message, "error", std::cerr);
+  }
+
+  void AddWarning(const string& filename, int line, int column,
+                  const string& message) {
+    AddErrorOrWarning(filename, line, column, message, "warning", std::clog);
+  }
 
+  // implements io::ErrorCollector -----------------------------------
+  void AddError(int line, int column, const string& message) {
+    AddError("input", line, column, message);
+  }
+
+  void AddWarning(int line, int column, const string& message) {
+    AddErrorOrWarning("input", line, column, message, "warning", std::clog);
+  }
+
+ private:
+  void AddErrorOrWarning(
+      const string& filename, int line, int column,
+      const string& message, const string& type, ostream& out) {
     // Print full path when running under MSVS
     string dfile;
     if (format_ == CommandLineInterface::ERROR_FORMAT_MSVS &&
         tree_ != NULL &&
         tree_->VirtualFileToDiskFile(filename, &dfile)) {
-      std::cerr << dfile;
+      out << dfile;
     } else {
-      std::cerr << filename;
+      out << filename;
     }
 
     // Users typically expect 1-based line/column numbers, so we add 1
@@ -288,24 +308,22 @@ class CommandLineInterface::ErrorPrinter : public MultiFileErrorCollector,
       // Allow for both GCC- and Visual-Studio-compatible output.
       switch (format_) {
         case CommandLineInterface::ERROR_FORMAT_GCC:
-          std::cerr << ":" << (line + 1) << ":" << (column + 1);
+          out << ":" << (line + 1) << ":" << (column + 1);
           break;
         case CommandLineInterface::ERROR_FORMAT_MSVS:
-          std::cerr << "(" << (line + 1)
-                    << ") : error in column=" << (column + 1);
+          out << "(" << (line + 1) << ") : "
+              << type << " in column=" << (column + 1);
           break;
       }
     }
 
-    std::cerr << ": " << message << std::endl;
-  }
-
-  // implements io::ErrorCollector -----------------------------------
-  void AddError(int line, int column, const string& message) {
-    AddError("input", line, column, message);
+    if (type == "warning") {
+      out << ": warning: " << message << std::endl;
+    } else {
+      out << ": " << message << std::endl;
+    }
   }
 
- private:
   const ErrorFormat format_;
   DiskSourceTree *tree_;
 };
@@ -1353,7 +1371,7 @@ void CommandLineInterface::PrintHelpText() {
 "                              defined in the given proto files. Groups share\n"
 "                              the same field number space with the parent \n"
 "                              message. Extension ranges are counted as \n"
-"                              occupied fields numbers."
+"                              occupied fields numbers.\n"
       << std::endl;
   if (!plugin_prefix_.empty()) {
     std::cerr <<
@@ -1443,6 +1461,7 @@ bool CommandLineInterface::GenerateDependencyManifestFile(
   for (int i = 0; i < parsed_files.size(); i++) {
     GetTransitiveDependencies(parsed_files[i],
                               false,
+                              false,
                               &already_seen,
                               file_set.mutable_file());
   }
@@ -1522,6 +1541,7 @@ bool CommandLineInterface::GeneratePluginOutput(
   for (int i = 0; i < parsed_files.size(); i++) {
     request.add_file_to_generate(parsed_files[i]->name());
     GetTransitiveDependencies(parsed_files[i],
+                              true,  // Include json_name for plugins.
                               true,  // Include source code info.
                               &already_seen, request.mutable_proto_file());
   }
@@ -1654,6 +1674,7 @@ bool CommandLineInterface::WriteDescriptorSet(
     set<const FileDescriptor*> already_seen;
     for (int i = 0; i < parsed_files.size(); i++) {
       GetTransitiveDependencies(parsed_files[i],
+                                true,  // Include json_name
                                 source_info_in_descriptor_set_,
                                 &already_seen, file_set.mutable_file());
     }
@@ -1665,6 +1686,7 @@ bool CommandLineInterface::WriteDescriptorSet(
       }
       FileDescriptorProto* file_proto = file_set.add_file();
       parsed_files[i]->CopyTo(file_proto);
+      parsed_files[i]->CopyJsonNameTo(file_proto);
       if (source_info_in_descriptor_set_) {
         parsed_files[i]->CopySourceCodeInfoTo(file_proto);
       }
@@ -1699,7 +1721,9 @@ bool CommandLineInterface::WriteDescriptorSet(
 }
 
 void CommandLineInterface::GetTransitiveDependencies(
-    const FileDescriptor* file, bool include_source_code_info,
+    const FileDescriptor* file,
+    bool include_json_name,
+    bool include_source_code_info,
     set<const FileDescriptor*>* already_seen,
     RepeatedPtrField<FileDescriptorProto>* output) {
   if (!already_seen->insert(file).second) {
@@ -1709,13 +1733,18 @@ void CommandLineInterface::GetTransitiveDependencies(
 
   // Add all dependencies.
   for (int i = 0; i < file->dependency_count(); i++) {
-    GetTransitiveDependencies(file->dependency(i), include_source_code_info,
+    GetTransitiveDependencies(file->dependency(i),
+                              include_json_name,
+                              include_source_code_info,
                               already_seen, output);
   }
 
   // Add this file.
   FileDescriptorProto* new_descriptor = output->Add();
   file->CopyTo(new_descriptor);
+  if (include_json_name) {
+    file->CopyJsonNameTo(new_descriptor);
+  }
   if (include_source_code_info) {
     file->CopySourceCodeInfoTo(new_descriptor);
   }
diff --git a/src/google/protobuf/compiler/command_line_interface.h b/src/google/protobuf/compiler/command_line_interface.h
index 7e611c44..f196ffc5 100644
--- a/src/google/protobuf/compiler/command_line_interface.h
+++ b/src/google/protobuf/compiler/command_line_interface.h
@@ -262,8 +262,11 @@ class LIBPROTOC_EXPORT CommandLineInterface {
   // in order.  Any files in *already_seen will not be added, and each file
   // added will be inserted into *already_seen.  If include_source_code_info is
   // true then include the source code information in the FileDescriptorProtos.
+  // If include_json_name is true, populate the json_name field of
+  // FieldDescriptorProto for all fields.
   static void GetTransitiveDependencies(
       const FileDescriptor* file,
+      bool include_json_name,
       bool include_source_code_info,
       set<const FileDescriptor*>* already_seen,
       RepeatedPtrField<FileDescriptorProto>* output);
diff --git a/src/google/protobuf/compiler/command_line_interface_unittest.cc b/src/google/protobuf/compiler/command_line_interface_unittest.cc
index fa792dae..4ce81a75 100644
--- a/src/google/protobuf/compiler/command_line_interface_unittest.cc
+++ b/src/google/protobuf/compiler/command_line_interface_unittest.cc
@@ -886,6 +886,10 @@ TEST_F(CommandLineInterfaceTest, WriteDescriptorSet) {
   EXPECT_EQ("bar.proto", descriptor_set.file(0).name());
   // Descriptor set should not have source code info.
   EXPECT_FALSE(descriptor_set.file(0).has_source_code_info());
+  // Descriptor set should have json_name.
+  EXPECT_EQ("Bar", descriptor_set.file(0).message_type(0).name());
+  EXPECT_EQ("foo", descriptor_set.file(0).message_type(0).field(0).name());
+  EXPECT_TRUE(descriptor_set.file(0).message_type(0).field(0).has_json_name());
 }
 
 TEST_F(CommandLineInterfaceTest, WriteDescriptorSetWithDuplicates) {
@@ -919,6 +923,10 @@ TEST_F(CommandLineInterfaceTest, WriteDescriptorSetWithDuplicates) {
   EXPECT_EQ("baz.proto", descriptor_set.file(2).name());
   // Descriptor set should not have source code info.
   EXPECT_FALSE(descriptor_set.file(0).has_source_code_info());
+  // Descriptor set should have json_name.
+  EXPECT_EQ("Bar", descriptor_set.file(0).message_type(0).name());
+  EXPECT_EQ("foo", descriptor_set.file(0).message_type(0).field(0).name());
+  EXPECT_TRUE(descriptor_set.file(0).message_type(0).field(0).has_json_name());
 }
 
 TEST_F(CommandLineInterfaceTest, WriteDescriptorSetWithSourceInfo) {
@@ -1413,6 +1421,18 @@ TEST_F(CommandLineInterfaceTest, PluginReceivesSourceCodeInfo) {
       "Saw message type MockCodeGenerator_HasSourceCodeInfo: 1.");
 }
 
+TEST_F(CommandLineInterfaceTest, PluginReceivesJsonName) {
+  CreateTempFile("foo.proto",
+    "syntax = \"proto2\";\n"
+    "message MockCodeGenerator_HasJsonName {\n"
+    "  optional int32 value = 1;\n"
+    "}\n");
+
+  Run("protocol_compiler --plug_out=$tmpdir --proto_path=$tmpdir foo.proto");
+
+  ExpectErrorSubstring("Saw json_name: 1");
+}
+
 TEST_F(CommandLineInterfaceTest, GeneratorPluginNotFound) {
   // Test what happens if the plugin isn't found.
 
diff --git a/src/google/protobuf/compiler/cpp/cpp_file.cc b/src/google/protobuf/compiler/cpp/cpp_file.cc
index 9aa41534..37e4bae4 100644
--- a/src/google/protobuf/compiler/cpp/cpp_file.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_file.cc
@@ -252,6 +252,7 @@ void FileGenerator::GenerateSource(io::Printer* printer) {
     "#include <algorithm>\n"    // for swap()
     "\n"
     "#include <google/protobuf/stubs/common.h>\n"
+    "#include <google/protobuf/stubs/port.h>\n"
     "#include <google/protobuf/stubs/once.h>\n"
     "#include <google/protobuf/io/coded_stream.h>\n"
     "#include <google/protobuf/wire_format_lite_inl.h>\n",
diff --git a/src/google/protobuf/compiler/importer.cc b/src/google/protobuf/compiler/importer.cc
index 8333684e..0d9093c0 100644
--- a/src/google/protobuf/compiler/importer.cc
+++ b/src/google/protobuf/compiler/importer.cc
@@ -185,6 +185,19 @@ void SourceTreeDescriptorDatabase::ValidationErrorCollector::AddError(
   owner_->error_collector_->AddError(filename, line, column, message);
 }
 
+void SourceTreeDescriptorDatabase::ValidationErrorCollector::AddWarning(
+    const string& filename,
+    const string& element_name,
+    const Message* descriptor,
+    ErrorLocation location,
+    const string& message) {
+  if (owner_->error_collector_ == NULL) return;
+
+  int line, column;
+  owner_->source_locations_.Find(descriptor, location, &line, &column);
+  owner_->error_collector_->AddWarning(filename, line, column, message);
+}
+
 // ===================================================================
 
 Importer::Importer(SourceTree* source_tree,
diff --git a/src/google/protobuf/compiler/importer.h b/src/google/protobuf/compiler/importer.h
index f010fd08..cc8fcc39 100644
--- a/src/google/protobuf/compiler/importer.h
+++ b/src/google/protobuf/compiler/importer.h
@@ -121,6 +121,12 @@ class LIBPROTOBUF_EXPORT SourceTreeDescriptorDatabase : public DescriptorDatabas
                   ErrorLocation location,
                   const string& message);
 
+    virtual void AddWarning(const string& filename,
+                            const string& element_name,
+                            const Message* descriptor,
+                            ErrorLocation location,
+                            const string& message);
+
    private:
     SourceTreeDescriptorDatabase* owner_;
   };
@@ -188,6 +194,9 @@ class LIBPROTOBUF_EXPORT MultiFileErrorCollector {
   virtual void AddError(const string& filename, int line, int column,
                         const string& message) = 0;
 
+  virtual void AddWarning(const string& filename, int line, int column,
+                          const string& message) {}
+
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MultiFileErrorCollector);
 };
diff --git a/src/google/protobuf/compiler/importer_unittest.cc b/src/google/protobuf/compiler/importer_unittest.cc
index 33c9328f..be19aa2e 100644
--- a/src/google/protobuf/compiler/importer_unittest.cc
+++ b/src/google/protobuf/compiler/importer_unittest.cc
@@ -71,6 +71,7 @@ class MockErrorCollector : public MultiFileErrorCollector {
   ~MockErrorCollector() {}
 
   string text_;
+  string warning_text_;
 
   // implements ErrorCollector ---------------------------------------
   void AddError(const string& filename, int line, int column,
@@ -78,6 +79,12 @@ class MockErrorCollector : public MultiFileErrorCollector {
     strings::SubstituteAndAppend(&text_, "$0:$1:$2: $3\n",
                                  filename, line, column, message);
   }
+
+  void AddWarning(const string& filename, int line, int column,
+                  const string& message) {
+    strings::SubstituteAndAppend(&warning_text_, "$0:$1:$2: $3\n",
+                                 filename, line, column, message);
+  }
 };
 
 // -------------------------------------------------------------------
@@ -123,6 +130,7 @@ class ImporterTest : public testing::Test {
 
   // Return the collected error text
   string error() const { return error_collector_.text_; }
+  string warning() const { return error_collector_.warning_text_; }
 
   MockErrorCollector error_collector_;
   MockSourceTree source_tree_;
diff --git a/src/google/protobuf/compiler/java/java_enum.cc b/src/google/protobuf/compiler/java/java_enum.cc
index 8a09f3a8..5fc9b002 100644
--- a/src/google/protobuf/compiler/java/java_enum.cc
+++ b/src/google/protobuf/compiler/java/java_enum.cc
@@ -85,17 +85,10 @@ EnumGenerator::~EnumGenerator() {}
 
 void EnumGenerator::Generate(io::Printer* printer) {
   WriteEnumDocComment(printer, descriptor_);
-  if (HasDescriptorMethods(descriptor_)) {
-    printer->Print(
-      "public enum $classname$\n"
-      "    implements com.google.protobuf.ProtocolMessageEnum {\n",
-      "classname", descriptor_->name());
-  } else {
-    printer->Print(
-      "public enum $classname$\n"
-      "    implements com.google.protobuf.Internal.EnumLite {\n",
-      "classname", descriptor_->name());
-  }
+  printer->Print(
+    "public enum $classname$\n"
+    "    implements com.google.protobuf.ProtocolMessageEnum {\n",
+    "classname", descriptor_->name());
   printer->Indent();
 
   for (int i = 0; i < canonical_values_.size(); i++) {
@@ -311,7 +304,6 @@ void EnumGenerator::Generate(io::Printer* printer) {
       "}\n"
       "\n");
 
-    // index is only used for reflection; lite implementation does not need it
     printer->Print("private final int index;\n");
   }
 
diff --git a/src/google/protobuf/compiler/java/java_enum_field_lite.cc b/src/google/protobuf/compiler/java/java_enum_field_lite.cc
index e8bf15d0..e3e87c58 100644
--- a/src/google/protobuf/compiler/java/java_enum_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_enum_field_lite.cc
@@ -596,9 +596,7 @@ GenerateInterfaceMembers(io::Printer* printer) const {
 void RepeatedImmutableEnumFieldLiteGenerator::
 GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
-    // TODO(dweis): Switch to IntList?
-    "private com.google.protobuf.Internal.ProtobufList<\n"
-    "    java.lang.Integer> $name$_;\n"
+    "private com.google.protobuf.Internal.IntList $name$_;\n"
     "private static final com.google.protobuf.Internal.ListAdapter.Converter<\n"
     "    java.lang.Integer, $type$> $name$_converter_ =\n"
     "        new com.google.protobuf.Internal.ListAdapter.Converter<\n"
@@ -623,7 +621,7 @@ GenerateMembers(io::Printer* printer) const {
   WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
-    "  return $name$_converter_.convert($name$_.get(index));\n"
+    "  return $name$_converter_.convert($name$_.getInt(index));\n"
     "}\n");
   if (SupportUnknownEnumValue(descriptor_->file())) {
     WriteFieldDocComment(printer, descriptor_);
@@ -635,7 +633,7 @@ GenerateMembers(io::Printer* printer) const {
     WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "$deprecation$public int get$capitalized_name$Value(int index) {\n"
-      "  return $name$_.get(index);\n"
+      "  return $name$_.getInt(index);\n"
       "}\n");
   }
 
@@ -649,7 +647,7 @@ GenerateMembers(io::Printer* printer) const {
   printer->Print(variables_,
     "private void ensure$capitalized_name$IsMutable() {\n"
     "  if (!$is_mutable$) {\n"
-    "    $name$_ = newProtobufList($name$_);\n"
+    "    $name$_ = newIntList($name$_);\n"
     "  }\n"
     "}\n");
   WriteFieldDocComment(printer, descriptor_);
@@ -660,7 +658,7 @@ GenerateMembers(io::Printer* printer) const {
     "    throw new NullPointerException();\n"
     "  }\n"
     "  ensure$capitalized_name$IsMutable();\n"
-    "  $name$_.set(index, value.getNumber());\n"
+    "  $name$_.setInt(index, value.getNumber());\n"
     "}\n");
   WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
@@ -669,7 +667,7 @@ GenerateMembers(io::Printer* printer) const {
     "    throw new NullPointerException();\n"
     "  }\n"
     "  ensure$capitalized_name$IsMutable();\n"
-    "  $name$_.add(value.getNumber());\n"
+    "  $name$_.addInt(value.getNumber());\n"
     "}\n");
   WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
@@ -677,13 +675,13 @@ GenerateMembers(io::Printer* printer) const {
     "    java.lang.Iterable<? extends $type$> values) {\n"
     "  ensure$capitalized_name$IsMutable();\n"
     "  for ($type$ value : values) {\n"
-    "    $name$_.add(value.getNumber());\n"
+    "    $name$_.addInt(value.getNumber());\n"
     "  }\n"
     "}\n");
   WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "private void clear$capitalized_name$() {\n"
-    "  $name$_ = emptyProtobufList();\n"
+    "  $name$_ = emptyIntList();\n"
     "}\n");
 
   if (SupportUnknownEnumValue(descriptor_->file())) {
@@ -692,13 +690,13 @@ GenerateMembers(io::Printer* printer) const {
       "private void set$capitalized_name$Value(\n"
       "    int index, int value) {\n"
       "  ensure$capitalized_name$IsMutable();\n"
-      "  $name$_.set(index, value);\n"
+      "  $name$_.setInt(index, value);\n"
       "}\n");
     WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
       "private void add$capitalized_name$Value(int value) {\n"
       "  ensure$capitalized_name$IsMutable();\n"
-      "  $name$_.add(value);\n"
+      "  $name$_.addInt(value);\n"
       "}\n");
     WriteFieldDocComment(printer, descriptor_);
     printer->Print(variables_,
@@ -706,7 +704,7 @@ GenerateMembers(io::Printer* printer) const {
       "    java.lang.Iterable<java.lang.Integer> values) {\n"
       "  ensure$capitalized_name$IsMutable();\n"
       "  for (int value : values) {\n"
-      "    $name$_.add(value);\n"
+      "    $name$_.addInt(value);\n"
       "  }\n"
       "}\n");
   }
@@ -805,7 +803,7 @@ GenerateFieldBuilderInitializationCode(io::Printer* printer)  const {
 
 void RepeatedImmutableEnumFieldLiteGenerator::
 GenerateInitializationCode(io::Printer* printer) const {
-  printer->Print(variables_, "$name$_ = emptyProtobufList();\n");
+  printer->Print(variables_, "$name$_ = emptyIntList();\n");
 }
 
 void RepeatedImmutableEnumFieldLiteGenerator::
@@ -840,9 +838,9 @@ GenerateParsingCode(io::Printer* printer) const {
     printer->Print(variables_,
       "int rawValue = input.readEnum();\n"
       "if (!$is_mutable$) {\n"
-      "  $name$_ = newProtobufList();\n"
+      "  $name$_ = newIntList();\n"
       "}\n"
-      "$name$_.add(rawValue);\n");
+      "$name$_.addInt(rawValue);\n");
   } else {
     printer->Print(variables_,
       "int rawValue = input.readEnum();\n"
@@ -855,9 +853,9 @@ GenerateParsingCode(io::Printer* printer) const {
     printer->Print(variables_,
       "} else {\n"
       "  if (!$is_mutable$) {\n"
-      "    $name$_ = newProtobufList();\n"
+      "    $name$_ = newIntList();\n"
       "  }\n"
-      "  $name$_.add(rawValue);\n"
+      "  $name$_.addInt(rawValue);\n"
       "}\n");
   }
 }
@@ -897,12 +895,12 @@ GenerateSerializationCode(io::Printer* printer) const {
       "  output.writeRawVarint32($name$MemoizedSerializedSize);\n"
       "}\n"
       "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.writeEnumNoTag($name$_.get(i));\n"
+      "  output.writeEnumNoTag($name$_.getInt(i));\n"
       "}\n");
   } else {
     printer->Print(variables_,
       "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.writeEnum($number$, $name$_.get(i));\n"
+      "  output.writeEnum($number$, $name$_.getInt(i));\n"
       "}\n");
   }
 }
@@ -917,7 +915,7 @@ GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(variables_,
     "for (int i = 0; i < $name$_.size(); i++) {\n"
     "  dataSize += com.google.protobuf.CodedOutputStream\n"
-    "    .computeEnumSizeNoTag($name$_.get(i));\n"
+    "    .computeEnumSizeNoTag($name$_.getInt(i));\n"
     "}\n");
   printer->Print(
     "size += dataSize;\n");
diff --git a/src/google/protobuf/compiler/java/java_enum_lite.cc b/src/google/protobuf/compiler/java/java_enum_lite.cc
index 62186386..ed415eee 100644
--- a/src/google/protobuf/compiler/java/java_enum_lite.cc
+++ b/src/google/protobuf/compiler/java/java_enum_lite.cc
@@ -85,34 +85,26 @@ EnumLiteGenerator::~EnumLiteGenerator() {}
 
 void EnumLiteGenerator::Generate(io::Printer* printer) {
   WriteEnumDocComment(printer, descriptor_);
-  if (HasDescriptorMethods(descriptor_)) {
-    printer->Print(
-      "public enum $classname$\n"
-      "    implements com.google.protobuf.ProtocolMessageEnum {\n",
-      "classname", descriptor_->name());
-  } else {
-    printer->Print(
-      "public enum $classname$\n"
-      "    implements com.google.protobuf.Internal.EnumLite {\n",
-      "classname", descriptor_->name());
-  }
+  printer->Print(
+    "public enum $classname$\n"
+    "    implements com.google.protobuf.Internal.EnumLite {\n",
+    "classname", descriptor_->name());
   printer->Indent();
 
   for (int i = 0; i < canonical_values_.size(); i++) {
     map<string, string> vars;
     vars["name"] = canonical_values_[i]->name();
-    vars["index"] = SimpleItoa(canonical_values_[i]->index());
     vars["number"] = SimpleItoa(canonical_values_[i]->number());
     WriteEnumValueDocComment(printer, canonical_values_[i]);
     if (canonical_values_[i]->options().deprecated()) {
       printer->Print("@java.lang.Deprecated\n");
     }
     printer->Print(vars,
-      "$name$($index$, $number$),\n");
+      "$name$($number$),\n");
   }
 
   if (SupportUnknownEnumValue(descriptor_->file())) {
-    printer->Print("UNRECOGNIZED(-1, -1),\n");
+    printer->Print("UNRECOGNIZED(-1),\n");
   }
 
   printer->Print(
@@ -145,15 +137,7 @@ void EnumLiteGenerator::Generate(io::Printer* printer) {
 
   printer->Print(
     "\n"
-    "public final int getNumber() {\n");
-  if (SupportUnknownEnumValue(descriptor_->file())) {
-    printer->Print(
-      "  if (index == -1) {\n"
-      "    throw new java.lang.IllegalArgumentException(\n"
-      "        \"Can't get the number of an unknown enum value.\");\n"
-      "  }\n");
-  }
-  printer->Print(
+    "public final int getNumber() {\n"
     "  return value;\n"
     "}\n"
     "\n"
@@ -193,7 +177,7 @@ void EnumLiteGenerator::Generate(io::Printer* printer) {
 
   printer->Print(
     "private final int value;\n\n"
-    "private $classname$(int index, int value) {\n",
+    "private $classname$(int value) {\n",
     "classname", descriptor_->name());
   printer->Print(
     "  this.value = value;\n"
diff --git a/src/google/protobuf/compiler/java/java_file.cc b/src/google/protobuf/compiler/java/java_file.cc
index 68b47ee1..c8172330 100644
--- a/src/google/protobuf/compiler/java/java_file.cc
+++ b/src/google/protobuf/compiler/java/java_file.cc
@@ -42,6 +42,7 @@
 
 #include <google/protobuf/compiler/java/java_context.h>
 #include <google/protobuf/compiler/java/java_enum.h>
+#include <google/protobuf/compiler/java/java_enum_lite.h>
 #include <google/protobuf/compiler/java/java_extension.h>
 #include <google/protobuf/compiler/java/java_generator_factory.h>
 #include <google/protobuf/compiler/java/java_helpers.h>
@@ -281,8 +282,13 @@ void FileGenerator::Generate(io::Printer* printer) {
 
   if (!MultipleJavaFiles(file_, immutable_api_)) {
     for (int i = 0; i < file_->enum_type_count(); i++) {
-      EnumGenerator(file_->enum_type(i), immutable_api_, context_.get())
-          .Generate(printer);
+      if (HasDescriptorMethods(file_)) {
+        EnumGenerator(file_->enum_type(i), immutable_api_, context_.get())
+            .Generate(printer);
+      } else {
+        EnumLiteGenerator(file_->enum_type(i), immutable_api_, context_.get())
+            .Generate(printer);
+      }
     }
     for (int i = 0; i < file_->message_type_count(); i++) {
       message_generators_[i]->GenerateInterface(printer);
@@ -543,13 +549,23 @@ void FileGenerator::GenerateSiblings(const string& package_dir,
                                      vector<string>* file_list) {
   if (MultipleJavaFiles(file_, immutable_api_)) {
     for (int i = 0; i < file_->enum_type_count(); i++) {
-      EnumGenerator generator(file_->enum_type(i), immutable_api_,
-                              context_.get());
-      GenerateSibling<EnumGenerator>(package_dir, java_package_,
-                                     file_->enum_type(i),
-                                     context, file_list, "",
-                                     &generator,
-                                     &EnumGenerator::Generate);
+      if (HasDescriptorMethods(file_)) {
+        EnumGenerator generator(file_->enum_type(i), immutable_api_,
+                                context_.get());
+        GenerateSibling<EnumGenerator>(package_dir, java_package_,
+                                       file_->enum_type(i),
+                                       context, file_list, "",
+                                       &generator,
+                                       &EnumGenerator::Generate);
+      } else {
+        EnumLiteGenerator generator(file_->enum_type(i), immutable_api_,
+                                    context_.get());
+        GenerateSibling<EnumLiteGenerator>(package_dir, java_package_,
+                                           file_->enum_type(i),
+                                           context, file_list, "",
+                                           &generator,
+                                           &EnumLiteGenerator::Generate);
+      }
     }
     for (int i = 0; i < file_->message_type_count(); i++) {
       if (immutable_api_) {
diff --git a/src/google/protobuf/compiler/java/java_primitive_field_lite.cc b/src/google/protobuf/compiler/java/java_primitive_field_lite.cc
index 392333b8..5a7bf82d 100644
--- a/src/google/protobuf/compiler/java/java_primitive_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_primitive_field_lite.cc
@@ -87,11 +87,13 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
       (*variables)["field_list_type"] =
           "com.google.protobuf.Internal." + capitalized_type + "List";
       (*variables)["new_list"] = "new" + capitalized_type + "List";
+      (*variables)["new_list_with_capacity"] =
+          "new" + capitalized_type + "ListWithCapacity";
       (*variables)["empty_list"] = "empty" + capitalized_type + "List()";
       (*variables)["make_name_unmodifiable"] =
           (*variables)["name"] + "_.makeImmutable()";
-      (*variables)["repeated_index_get"] =
-          (*variables)["name"] + "_.get" + capitalized_type + "(index)";
+      (*variables)["repeated_get"] =
+          (*variables)["name"] + "_.get" + capitalized_type;
       (*variables)["repeated_add"] =
           (*variables)["name"] + "_.add" + capitalized_type;
       (*variables)["repeated_set"] =
@@ -102,11 +104,11 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
           "com.google.protobuf.Internal.ProtobufList<" +
           (*variables)["boxed_type"] + ">";
       (*variables)["new_list"] = "newProtobufList";
+      (*variables)["new_list_with_capacity"] = "newProtobufListWithCapacity";
       (*variables)["empty_list"] = "emptyProtobufList()";
       (*variables)["make_name_unmodifiable"] =
           (*variables)["name"] + "_.makeImmutable()";
-      (*variables)["repeated_index_get"] =
-          (*variables)["name"] + "_.get(index)";
+      (*variables)["repeated_get"] = (*variables)["name"] + "_.get";
       (*variables)["repeated_add"] = (*variables)["name"] + "_.add";
       (*variables)["repeated_set"] = (*variables)["name"] + "_.set";
   }
@@ -629,7 +631,7 @@ GenerateMembers(io::Printer* printer) const {
   WriteFieldDocComment(printer, descriptor_);
   printer->Print(variables_,
     "$deprecation$public $type$ get$capitalized_name$(int index) {\n"
-    "  return $repeated_index_get$;\n"
+    "  return $repeated_get$(index);\n"
     "}\n");
 
   if (descriptor_->options().packed() &&
@@ -773,6 +775,9 @@ GenerateDynamicMethodMakeImmutableCode(io::Printer* printer) const {
 
 void RepeatedImmutablePrimitiveFieldLiteGenerator::
 GenerateParsingCode(io::Printer* printer) const {
+  // TODO(dweis): Scan the input buffer to count, then initialize
+  // appropriately.
+  // TODO(dweis): Scan the input buffer to count and ensure capacity.
   printer->Print(variables_,
     "if (!$is_mutable$) {\n"
     "  $name$_ = $new_list$();\n"
@@ -785,8 +790,21 @@ GenerateParsingCodeFromPacked(io::Printer* printer) const {
   printer->Print(variables_,
     "int length = input.readRawVarint32();\n"
     "int limit = input.pushLimit(length);\n"
-    "if (!$is_mutable$ && input.getBytesUntilLimit() > 0) {\n"
-    "  $name$_ = $new_list$();\n"
+    "if (!$is_mutable$ && input.getBytesUntilLimit() > 0) {\n");
+
+  int fixed_size = FixedSize(GetType(descriptor_));
+  if (fixed_size == -1) {
+    // TODO(dweis): Scan the input buffer to count, then initialize
+    // appropriately.
+    printer->Print(variables_,
+      "  $name$_ = $new_list$();\n");
+  } else {
+    printer->Print(variables_,
+      "  $name$_ = $new_list_with_capacity$(length/$fixed_size$);\n");
+  }
+
+  // TODO(dweis): Scan the input buffer to count and ensure capacity.
+  printer->Print(variables_,
     "}\n"
     "while (input.getBytesUntilLimit() > 0) {\n"
     "  $repeated_add$(input.read$capitalized_type$());\n"
@@ -814,12 +832,12 @@ GenerateSerializationCode(io::Printer* printer) const {
       "  output.writeRawVarint32($name$MemoizedSerializedSize);\n"
       "}\n"
       "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.write$capitalized_type$NoTag($name$_.get(i));\n"
+      "  output.write$capitalized_type$NoTag($repeated_get$(i));\n"
       "}\n");
   } else {
     printer->Print(variables_,
       "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.write$capitalized_type$($number$, $name$_.get(i));\n"
+      "  output.write$capitalized_type$($number$, $repeated_get$(i));\n"
       "}\n");
   }
 }
@@ -835,7 +853,7 @@ GenerateSerializedSizeCode(io::Printer* printer) const {
     printer->Print(variables_,
       "for (int i = 0; i < $name$_.size(); i++) {\n"
       "  dataSize += com.google.protobuf.CodedOutputStream\n"
-      "    .compute$capitalized_type$SizeNoTag($name$_.get(i));\n"
+      "    .compute$capitalized_type$SizeNoTag($repeated_get$(i));\n"
       "}\n");
   } else {
     printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/java/java_string_field.cc b/src/google/protobuf/compiler/java/java_string_field.cc
index 72ebaeca..7f757e47 100644
--- a/src/google/protobuf/compiler/java/java_string_field.cc
+++ b/src/google/protobuf/compiler/java/java_string_field.cc
@@ -405,7 +405,7 @@ void ImmutableStringFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   if (CheckUtf8(descriptor_)) {
     printer->Print(variables_,
-      "String s = input.readStringRequireUtf8();\n"
+      "java.lang.String s = input.readStringRequireUtf8();\n"
       "$set_has_field_bit_message$\n"
       "$name$_ = s;\n");
   } else if (!HasDescriptorMethods(descriptor_->file())) {
@@ -414,7 +414,7 @@ GenerateParsingCode(io::Printer* printer) const {
     // spurious intermediary ByteString allocations, cutting overall allocations
     // in half.
     printer->Print(variables_,
-      "String s = input.readString();\n"
+      "java.lang.String s = input.readString();\n"
       "$set_has_field_bit_message$\n"
       "$name$_ = s;\n");
   } else {
@@ -665,7 +665,7 @@ void ImmutableStringOneofFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   if (CheckUtf8(descriptor_)) {
     printer->Print(variables_,
-      "String s = input.readStringRequireUtf8();\n"
+      "java.lang.String s = input.readStringRequireUtf8();\n"
       "$set_oneof_case_message$;\n"
       "$oneof_name$_ = s;\n");
   } else if (!HasDescriptorMethods(descriptor_->file())) {
@@ -674,7 +674,7 @@ GenerateParsingCode(io::Printer* printer) const {
     // spurious intermediary ByteString allocations, cutting overall allocations
     // in half.
     printer->Print(variables_,
-      "String s = input.readString();\n"
+      "java.lang.String s = input.readString();\n"
       "$set_oneof_case_message$;\n"
       "$oneof_name$_ = s;\n");
   } else {
@@ -773,12 +773,6 @@ GenerateMembers(io::Printer* printer) const {
     "    get$capitalized_name$Bytes(int index) {\n"
     "  return $name$_.getByteString(index);\n"
     "}\n");
-
-  if (descriptor_->options().packed() &&
-      HasGeneratedMethods(descriptor_->containing_type())) {
-    printer->Print(variables_,
-      "private int $name$MemoizedSerializedSize = -1;\n");
-  }
 }
 
 void RepeatedImmutableStringFieldGenerator::
@@ -939,14 +933,14 @@ void RepeatedImmutableStringFieldGenerator::
 GenerateParsingCode(io::Printer* printer) const {
   if (CheckUtf8(descriptor_)) {
     printer->Print(variables_,
-    "String s = input.readStringRequireUtf8();\n");
+    "java.lang.String s = input.readStringRequireUtf8();\n");
   } else if (!HasDescriptorMethods(descriptor_->file())) {
     // Lite runtime should attempt to reduce allocations by attempting to
     // construct the string directly from the input stream buffer. This avoids
     // spurious intermediary ByteString allocations, cutting overall allocations
     // in half.
     printer->Print(variables_,
-    "String s = input.readString();\n");
+    "java.lang.String s = input.readString();\n");
   } else {
     printer->Print(variables_,
     "com.google.protobuf.ByteString bs = input.readBytes();\n");
@@ -966,30 +960,6 @@ GenerateParsingCode(io::Printer* printer) const {
 }
 
 void RepeatedImmutableStringFieldGenerator::
-GenerateParsingCodeFromPacked(io::Printer* printer) const {
-  printer->Print(variables_,
-    "int length = input.readRawVarint32();\n"
-    "int limit = input.pushLimit(length);\n"
-    "if (!$get_mutable_bit_parser$ && input.getBytesUntilLimit() > 0) {\n"
-    "  $name$_ = new com.google.protobuf.LazyStringArrayList();\n"
-    "  $set_mutable_bit_parser$;\n"
-    "}\n"
-    "while (input.getBytesUntilLimit() > 0) {\n");
-  if (CheckUtf8(descriptor_)) {
-    printer->Print(variables_,
-      "  String s = input.readStringRequireUtf8();\n");
-  } else {
-    printer->Print(variables_,
-      "  String s = input.readString();\n");
-  }
-  printer->Print(variables_,
-    "  $name$.add(s);\n");
-  printer->Print(variables_,
-    "}\n"
-    "input.popLimit(limit);\n");
-}
-
-void RepeatedImmutableStringFieldGenerator::
 GenerateParsingDoneCode(io::Printer* printer) const {
   printer->Print(variables_,
     "if ($get_mutable_bit_parser$) {\n"
@@ -999,21 +969,10 @@ GenerateParsingDoneCode(io::Printer* printer) const {
 
 void RepeatedImmutableStringFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "if (get$capitalized_name$List().size() > 0) {\n"
-      "  output.writeRawVarint32($tag$);\n"
-      "  output.writeRawVarint32($name$MemoizedSerializedSize);\n"
-      "}\n"
-      "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  writeStringNoTag(output, $name$_.getRaw(i));\n"
-      "}\n");
-  } else {
-    printer->Print(variables_,
-      "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  $writeString$(output, $number$, $name$_.getRaw(i));\n"
-      "}\n");
-  }
+  printer->Print(variables_,
+    "for (int i = 0; i < $name$_.size(); i++) {\n"
+    "  $writeString$(output, $number$, $name$_.getRaw(i));\n"
+    "}\n");
 }
 
 void RepeatedImmutableStringFieldGenerator::
@@ -1031,23 +990,8 @@ GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(
       "size += dataSize;\n");
 
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "if (!get$capitalized_name$List().isEmpty()) {\n"
-      "  size += $tag_size$;\n"
-      "  size += com.google.protobuf.CodedOutputStream\n"
-      "      .computeInt32SizeNoTag(dataSize);\n"
-      "}\n");
-  } else {
-    printer->Print(variables_,
-      "size += $tag_size$ * get$capitalized_name$List().size();\n");
-  }
-
-  // cache the data size for packed fields.
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "$name$MemoizedSerializedSize = dataSize;\n");
-  }
+  printer->Print(variables_,
+    "size += $tag_size$ * get$capitalized_name$List().size();\n");
 
   printer->Outdent();
   printer->Print("}\n");
diff --git a/src/google/protobuf/compiler/java/java_string_field.h b/src/google/protobuf/compiler/java/java_string_field.h
index 1ea44dec..a3b57351 100644
--- a/src/google/protobuf/compiler/java/java_string_field.h
+++ b/src/google/protobuf/compiler/java/java_string_field.h
@@ -131,7 +131,6 @@ class RepeatedImmutableStringFieldGenerator : public ImmutableFieldGenerator {
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateBuildingCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
-  void GenerateParsingCodeFromPacked(io::Printer* printer) const;
   void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/java/java_string_field_lite.cc b/src/google/protobuf/compiler/java/java_string_field_lite.cc
index 092e3c29..eb5964bd 100644
--- a/src/google/protobuf/compiler/java/java_string_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_string_field_lite.cc
@@ -647,12 +647,6 @@ GenerateMembers(io::Printer* printer) const {
     "      $name$_.get(index));\n"
     "}\n");
 
-  if (descriptor_->options().packed() &&
-      HasGeneratedMethods(descriptor_->containing_type())) {
-    printer->Print(variables_,
-      "private int $name$MemoizedSerializedSize = -1;\n");
-  }
-
   printer->Print(variables_,
     "private void ensure$capitalized_name$IsMutable() {\n"
     "  if (!$is_mutable$) {\n"
@@ -835,29 +829,6 @@ GenerateParsingCode(io::Printer* printer) const {
 }
 
 void RepeatedImmutableStringFieldLiteGenerator::
-GenerateParsingCodeFromPacked(io::Printer* printer) const {
-  printer->Print(variables_,
-    "int length = input.readRawVarint32();\n"
-    "int limit = input.pushLimit(length);\n"
-    "if (!$is_mutable$ && input.getBytesUntilLimit() > 0) {\n"
-    "  $name$_ = com.google.protobuf.GeneratedMessageLite.newProtobufList();\n"
-    "}\n"
-    "while (input.getBytesUntilLimit() > 0) {\n");
-  if (CheckUtf8(descriptor_)) {
-    printer->Print(variables_,
-      "  String s = input.readStringRequireUtf8();\n");
-  } else {
-    printer->Print(variables_,
-      "  String s = input.readString();\n");
-  }
-  printer->Print(variables_,
-    "  $name$.add(s);\n");
-  printer->Print(variables_,
-    "}\n"
-    "input.popLimit(limit);\n");
-}
-
-void RepeatedImmutableStringFieldLiteGenerator::
 GenerateParsingDoneCode(io::Printer* printer) const {
   printer->Print(variables_,
     "if ($is_mutable$) {\n"
@@ -870,21 +841,10 @@ GenerateSerializationCode(io::Printer* printer) const {
   // Lite runtime should reduce allocations by serializing the string directly.
   // This avoids spurious intermediary ByteString allocations, cutting overall
   // allocations in half.
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "if (get$capitalized_name$List().size() > 0) {\n"
-      "  output.writeRawVarint32($tag$);\n"
-      "  output.writeRawVarint32($name$MemoizedSerializedSize);\n"
-      "}\n"
-      "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.writeStringNoTag($name$_.get(i));\n"
-      "}\n");
-  } else {
-    printer->Print(variables_,
-      "for (int i = 0; i < $name$_.size(); i++) {\n"
-      "  output.writeString($number$, $name$_.get(i));\n"
-      "}\n");
-  }
+  printer->Print(variables_,
+    "for (int i = 0; i < $name$_.size(); i++) {\n"
+    "  output.writeString($number$, $name$_.get(i));\n"
+    "}\n");
 }
 
 void RepeatedImmutableStringFieldLiteGenerator::
@@ -906,23 +866,9 @@ GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(
       "size += dataSize;\n");
 
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "if (!get$capitalized_name$List().isEmpty()) {\n"
-      "  size += $tag_size$;\n"
-      "  size += com.google.protobuf.CodedOutputStream\n"
-      "      .computeInt32SizeNoTag(dataSize);\n"
-      "}\n");
-  } else {
-    printer->Print(variables_,
-      "size += $tag_size$ * get$capitalized_name$List().size();\n");
-  }
 
-  // cache the data size for packed fields.
-  if (descriptor_->options().packed()) {
-    printer->Print(variables_,
-      "$name$MemoizedSerializedSize = dataSize;\n");
-  }
+  printer->Print(variables_,
+    "size += $tag_size$ * get$capitalized_name$List().size();\n");
 
   printer->Outdent();
   printer->Print("}\n");
diff --git a/src/google/protobuf/compiler/java/java_string_field_lite.h b/src/google/protobuf/compiler/java/java_string_field_lite.h
index 9d93b307..4d9b4bd7 100644
--- a/src/google/protobuf/compiler/java/java_string_field_lite.h
+++ b/src/google/protobuf/compiler/java/java_string_field_lite.h
@@ -129,7 +129,6 @@ class RepeatedImmutableStringFieldLiteGenerator
   void GenerateMergingCode(io::Printer* printer) const;
   void GenerateDynamicMethodMakeImmutableCode(io::Printer* printer) const;
   void GenerateParsingCode(io::Printer* printer) const;
-  void GenerateParsingCodeFromPacked(io::Printer* printer) const;
   void GenerateParsingDoneCode(io::Printer* printer) const;
   void GenerateSerializationCode(io::Printer* printer) const;
   void GenerateSerializedSizeCode(io::Printer* printer) const;
diff --git a/src/google/protobuf/compiler/js/js_generator.cc b/src/google/protobuf/compiler/js/js_generator.cc
new file mode 100755
index 00000000..1e308464
--- /dev/null
+++ b/src/google/protobuf/compiler/js/js_generator.cc
@@ -0,0 +1,2620 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <google/protobuf/compiler/js/js_generator.h>
+
+#include <assert.h>
+#include <algorithm>
+#include <limits>
+#include <map>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <google/protobuf/stubs/logging.h>
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/stringprintf.h>
+#include <google/protobuf/io/printer.h>
+#include <google/protobuf/io/zero_copy_stream.h>
+#include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/stubs/strutil.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace js {
+
+// Sorted list of JavaScript keywords. These cannot be used as names. If they
+// appear, we prefix them with "pb_".
+const char* kKeyword[] = {
+  "abstract",
+  "boolean",
+  "break",
+  "byte",
+  "case",
+  "catch",
+  "char",
+  "class",
+  "const",
+  "continue",
+  "debugger",
+  "default",
+  "delete",
+  "do",
+  "double",
+  "else",
+  "enum",
+  "export",
+  "extends",
+  "false",
+  "final",
+  "finally",
+  "float",
+  "for",
+  "function",
+  "goto",
+  "if",
+  "implements",
+  "import",
+  "in",
+  "instanceof",
+  "int",
+  "interface",
+  "long",
+  "native",
+  "new",
+  "null",
+  "package",
+  "private",
+  "protected",
+  "public",
+  "return",
+  "short",
+  "static",
+  "super",
+  "switch",
+  "synchronized",
+  "this",
+  "throw",
+  "throws",
+  "transient",
+  "try",
+  "typeof",
+  "var",
+  "void",
+  "volatile",
+  "while",
+  "with",
+};
+
+static const int kNumKeyword = sizeof(kKeyword) / sizeof(char*);
+
+namespace {
+
+bool IsReserved(const string& ident) {
+  for (int i = 0; i < kNumKeyword; i++) {
+    if (ident == kKeyword[i]) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Returns a copy of |filename| with any trailing ".protodevel" or ".proto
+// suffix stripped.
+string StripProto(const string& filename) {
+  const char* suffix = HasSuffixString(filename, ".protodevel")
+      ? ".protodevel" : ".proto";
+  return StripSuffixString(filename, suffix);
+}
+
+// Returns the fully normalized JavaScript path for the given
+// file descriptor's package.
+string GetPath(const GeneratorOptions& options,
+               const FileDescriptor* file) {
+  if (!options.namespace_prefix.empty()) {
+    return options.namespace_prefix;
+  } else if (!file->package().empty()) {
+    return "proto." + file->package();
+  } else {
+    return "proto";
+  }
+}
+
+// Forward declare, so that GetPrefix can call this method,
+// which in turn, calls GetPrefix.
+string GetPath(const GeneratorOptions& options,
+               const Descriptor* descriptor);
+
+// Returns the path prefix for a message or enumeration that
+// lives under the given file and containing type.
+string GetPrefix(const GeneratorOptions& options,
+                 const FileDescriptor* file_descriptor,
+                 const Descriptor* containing_type) {
+  string prefix = "";
+
+  if (containing_type == NULL) {
+    prefix = GetPath(options, file_descriptor);
+  } else {
+    prefix = GetPath(options, containing_type);
+  }
+
+  if (!prefix.empty()) {
+    prefix += ".";
+  }
+
+  return prefix;
+}
+
+
+// Returns the fully normalized JavaScript path for the given
+// message descriptor.
+string GetPath(const GeneratorOptions& options,
+               const Descriptor* descriptor) {
+  return GetPrefix(
+      options, descriptor->file(),
+      descriptor->containing_type()) + descriptor->name();
+}
+
+
+// Returns the fully normalized JavaScript path for the given
+// field's containing message descriptor.
+string GetPath(const GeneratorOptions& options,
+               const FieldDescriptor* descriptor) {
+  return GetPath(options, descriptor->containing_type());
+}
+
+// Returns the fully normalized JavaScript path for the given
+// enumeration descriptor.
+string GetPath(const GeneratorOptions& options,
+               const EnumDescriptor* enum_descriptor) {
+  return GetPrefix(
+      options, enum_descriptor->file(),
+      enum_descriptor->containing_type()) + enum_descriptor->name();
+}
+
+
+// Returns the fully normalized JavaScript path for the given
+// enumeration value descriptor.
+string GetPath(const GeneratorOptions& options,
+               const EnumValueDescriptor* value_descriptor) {
+  return GetPath(
+      options,
+      value_descriptor->type()) + "." + value_descriptor->name();
+}
+
+// - Object field name: LOWER_UNDERSCORE -> LOWER_CAMEL, except for group fields
+// (UPPER_CAMEL -> LOWER_CAMEL), with "List" (or "Map") appended if appropriate,
+// and with reserved words triggering a "pb_" prefix.
+// - Getters/setters: LOWER_UNDERSCORE -> UPPER_CAMEL, except for group fields
+// (use the name directly), then append "List" if appropriate, then append "$"
+// if resulting name is equal to a reserved word.
+// - Enums: just uppercase.
+
+// Locale-independent version of ToLower that deals only with ASCII A-Z.
+char ToLowerASCII(char c) {
+  if (c >= 'A' && c <= 'Z') {
+    return (c - 'A') + 'a';
+  } else {
+    return c;
+  }
+}
+
+vector<string> ParseLowerUnderscore(const string& input) {
+  vector<string> words;
+  string running = "";
+  for (int i = 0; i < input.size(); i++) {
+    if (input[i] == '_') {
+      if (!running.empty()) {
+        words.push_back(running);
+        running.clear();
+      }
+    } else {
+      running += ToLowerASCII(input[i]);
+    }
+  }
+  if (!running.empty()) {
+    words.push_back(running);
+  }
+  return words;
+}
+
+vector<string> ParseUpperCamel(const string& input) {
+  vector<string> words;
+  string running = "";
+  for (int i = 0; i < input.size(); i++) {
+    if (input[i] >= 'A' && input[i] <= 'Z' && !running.empty()) {
+      words.push_back(running);
+      running.clear();
+    }
+    running += ToLowerASCII(input[i]);
+  }
+  if (!running.empty()) {
+    words.push_back(running);
+  }
+  return words;
+}
+
+string ToLowerCamel(const vector<string>& words) {
+  string result;
+  for (int i = 0; i < words.size(); i++) {
+    string word = words[i];
+    if (i == 0 && (word[0] >= 'A' && word[0] <= 'Z')) {
+      word[0] = (word[0] - 'A') + 'a';
+    } else if (i != 0 && (word[0] >= 'a' && word[0] <= 'z')) {
+      word[0] = (word[0] - 'a') + 'A';
+    }
+    result += word;
+  }
+  return result;
+}
+
+string ToUpperCamel(const vector<string>& words) {
+  string result;
+  for (int i = 0; i < words.size(); i++) {
+    string word = words[i];
+    if (word[0] >= 'a' && word[0] <= 'z') {
+      word[0] = (word[0] - 'a') + 'A';
+    }
+    result += word;
+  }
+  return result;
+}
+
+// Based on code from descriptor.cc (Thanks Kenton!)
+// Uppercases the entire string, turning ValueName into
+// VALUENAME.
+string ToEnumCase(const string& input) {
+  string result;
+  result.reserve(input.size());
+
+  for (int i = 0; i < input.size(); i++) {
+    if ('a' <= input[i] && input[i] <= 'z') {
+      result.push_back(input[i] - 'a' + 'A');
+    } else {
+      result.push_back(input[i]);
+    }
+  }
+
+  return result;
+}
+
+string ToFileName(const string& input) {
+  string result;
+  result.reserve(input.size());
+
+  for (int i = 0; i < input.size(); i++) {
+    if ('A' <= input[i] && input[i] <= 'Z') {
+      result.push_back(input[i] - 'A' + 'a');
+    } else {
+      result.push_back(input[i]);
+    }
+  }
+
+  return result;
+}
+
+// Returns the message/response ID, if set.
+string GetMessageId(const Descriptor* desc) {
+  return string();
+}
+
+
+// Used inside Google only -- do not remove.
+bool IsResponse(const Descriptor* desc) { return false; }
+bool IgnoreField(const FieldDescriptor* field) { return false; }
+
+
+// Does JSPB ignore this entire oneof? True only if all fields are ignored.
+bool IgnoreOneof(const OneofDescriptor* oneof) {
+  for (int i = 0; i < oneof->field_count(); i++) {
+    if (!IgnoreField(oneof->field(i))) {
+      return false;
+    }
+  }
+  return true;
+}
+
+string JSIdent(const FieldDescriptor* field,
+               bool is_upper_camel,
+               bool is_map) {
+  string result;
+  if (field->type() == FieldDescriptor::TYPE_GROUP) {
+    result = is_upper_camel ?
+        ToUpperCamel(ParseUpperCamel(field->message_type()->name())) :
+        ToLowerCamel(ParseUpperCamel(field->message_type()->name()));
+  } else {
+    result = is_upper_camel ?
+        ToUpperCamel(ParseLowerUnderscore(field->name())) :
+        ToLowerCamel(ParseLowerUnderscore(field->name()));
+  }
+  if (is_map) {
+    result += "Map";
+  } else if (field->is_repeated()) {
+    result += "List";
+  }
+  return result;
+}
+
+string JSObjectFieldName(const FieldDescriptor* field) {
+  string name = JSIdent(
+      field,
+      /* is_upper_camel = */ false,
+      /* is_map = */ false);
+  if (IsReserved(name)) {
+    name = "pb_" + name;
+  }
+  return name;
+}
+
+// Returns the field name as a capitalized portion of a getter/setter method
+// name, e.g. MyField for .getMyField().
+string JSGetterName(const FieldDescriptor* field) {
+  string name = JSIdent(field,
+                        /* is_upper_camel = */ true,
+                        /* is_map = */ false);
+  if (name == "Extension" || name == "JsPbMessageId") {
+    // Avoid conflicts with base-class names.
+    name += "$";
+  }
+  return name;
+}
+
+string JSMapGetterName(const FieldDescriptor* field) {
+  return JSIdent(field,
+                 /* is_upper_camel = */ true,
+                 /* is_map = */ true);
+}
+
+
+
+string JSOneofName(const OneofDescriptor* oneof) {
+  return ToUpperCamel(ParseLowerUnderscore(oneof->name()));
+}
+
+// Returns the index corresponding to this field in the JSPB array (underlying
+// data storage array).
+string JSFieldIndex(const FieldDescriptor* field) {
+  // Determine whether this field is a member of a group. Group fields are a bit
+  // wonky: their "containing type" is a message type created just for the
+  // group, and that type's parent type has a field with the group-message type
+  // as its message type and TYPE_GROUP as its field type. For such fields, the
+  // index we use is relative to the field number of the group submessage field.
+  // For all other fields, we just use the field number.
+  const Descriptor* containing_type = field->containing_type();
+  const Descriptor* parent_type = containing_type->containing_type();
+  if (parent_type != NULL) {
+    for (int i = 0; i < parent_type->field_count(); i++) {
+      if (parent_type->field(i)->type() == FieldDescriptor::TYPE_GROUP &&
+          parent_type->field(i)->message_type() == containing_type) {
+        return SimpleItoa(field->number() - parent_type->field(i)->number());
+      }
+    }
+  }
+  return SimpleItoa(field->number());
+}
+
+string JSOneofIndex(const OneofDescriptor* oneof) {
+  int index = -1;
+  for (int i = 0; i < oneof->containing_type()->oneof_decl_count(); i++) {
+    const OneofDescriptor* o = oneof->containing_type()->oneof_decl(i);
+    // If at least one field in this oneof is not JSPB-ignored, count the oneof.
+    for (int j = 0; j < o->field_count(); j++) {
+      const FieldDescriptor* f = o->field(j);
+      if (!IgnoreField(f)) {
+        index++;
+        break;  // inner loop
+      }
+    }
+    if (o == oneof) {
+      break;
+    }
+  }
+  return SimpleItoa(index);
+}
+
+// Decodes a codepoint in \x0000 -- \xFFFF. Since JS strings are UTF-16, we only
+// need to handle the BMP (16-bit range) here.
+uint16_t DecodeUTF8Codepoint(uint8_t* bytes, size_t* length) {
+  if (*length == 0) {
+    return 0;
+  }
+  size_t expected = 0;
+  if ((*bytes & 0x80) == 0) {
+    expected = 1;
+  } else if ((*bytes & 0xe0) == 0xc0) {
+    expected = 2;
+  } else if ((*bytes & 0xf0) == 0xe0) {
+    expected = 3;
+  } else {
+    // Too long -- don't accept.
+    *length = 0;
+    return 0;
+  }
+
+  if (*length < expected) {
+    // Not enough bytes -- don't accept.
+    *length = 0;
+    return 0;
+  }
+
+  *length = expected;
+  switch (expected) {
+    case 1: return bytes[0];
+    case 2: return ((bytes[0] & 0x1F) << 6)  |
+                   ((bytes[1] & 0x3F) << 0);
+    case 3: return ((bytes[0] & 0x0F) << 12) |
+                   ((bytes[1] & 0x3F) << 6)  |
+                   ((bytes[2] & 0x3F) << 0);
+    default: return 0;
+  }
+}
+
+// Escapes the contents of a string to be included within double-quotes ("") in
+// JavaScript. |is_utf8| determines whether the input data (in a C++ string of
+// chars) is UTF-8 encoded (in which case codepoints become JavaScript string
+// characters, escaped with 16-bit hex escapes where necessary) or raw binary
+// (in which case bytes become JavaScript string characters 0 -- 255).
+string EscapeJSString(const string& in, bool is_utf8) {
+  string result;
+  size_t decoded = 0;
+  for (size_t i = 0; i < in.size(); i += decoded) {
+    uint16_t codepoint = 0;
+    if (is_utf8) {
+      // Decode the next UTF-8 codepoint.
+      size_t have_bytes = in.size() - i;
+      uint8_t bytes[3] = {
+        static_cast<uint8_t>(in[i]),
+        static_cast<uint8_t>(((i + 1) < in.size()) ? in[i + 1] : 0),
+        static_cast<uint8_t>(((i + 2) < in.size()) ? in[i + 2] : 0),
+      };
+      codepoint = DecodeUTF8Codepoint(bytes, &have_bytes);
+      if (have_bytes == 0) {
+        break;
+      }
+      decoded = have_bytes;
+    } else {
+      codepoint = static_cast<uint16_t>(static_cast<uint8_t>(in[i]));
+      decoded = 1;
+    }
+
+    // Next byte -- used for minimal octal escapes below.
+    char next_byte = (i + decoded) < in.size() ?
+        in[i + decoded] : 0;
+    bool pad_octal = (next_byte >= '0' && next_byte <= '7');
+
+    switch (codepoint) {
+      case '\0': result += pad_octal ? "\\000" : "\\0";   break;
+      case '\b': result += "\\\b";  break;
+      case '\t': result += "\\\t";  break;
+      case '\n': result += "\\\n";  break;
+      case '\r': result += "\\\r";  break;
+      case '\f': result += "\\\f";  break;
+      case '\\': result += "\\\\";  break;
+      case '"':  result += pad_octal ? "\\042" : "\\42"; break;
+      case '&':  result += pad_octal ? "\\046" : "\\46"; break;
+      case '\'': result += pad_octal ? "\\047" : "\\47"; break;
+      case '<':  result += pad_octal ? "\\074" : "\\74"; break;
+      case '=':  result += pad_octal ? "\\075" : "\\75"; break;
+      case '>':  result += pad_octal ? "\\076" : "\\76"; break;
+      default:
+        // All other non-ASCII codepoints are escaped.
+        // Original codegen uses hex for >= 0x100 and octal for others.
+        if (codepoint >= 0x20 && codepoint <= 0x7e) {
+          result += static_cast<char>(codepoint);
+        } else {
+          if (codepoint >= 0x100) {
+            result += StringPrintf("\\u%04x", codepoint);
+          } else {
+            if (pad_octal || codepoint >= 0100) {
+              result += "\\";
+              result += ('0' + ((codepoint >> 6) & 07));
+              result += ('0' + ((codepoint >> 3) & 07));
+              result += ('0' + ((codepoint >> 0) & 07));
+            } else if (codepoint >= 010) {
+              result += "\\";
+              result += ('0' + ((codepoint >> 3) & 07));
+              result += ('0' + ((codepoint >> 0) & 07));
+            } else {
+              result += "\\";
+              result += ('0' + ((codepoint >> 0) & 07));
+            }
+          }
+        }
+        break;
+    }
+  }
+  return result;
+}
+
+string EscapeBase64(const string& in) {
+  static const char* kAlphabet =
+      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+  string result;
+
+  for (size_t i = 0; i < in.size(); i += 3) {
+    int value = (in[i] << 16) |
+        (((i + 1) < in.size()) ? (in[i + 1] << 8) : 0) |
+        (((i + 2) < in.size()) ? (in[i + 2] << 0) : 0);
+    result += kAlphabet[(value >> 18) & 0x3f];
+    result += kAlphabet[(value >> 12) & 0x3f];
+    if ((i + 1) < in.size()) {
+      result += kAlphabet[(value >>  6) & 0x3f];
+    } else {
+      result += '=';
+    }
+    if ((i + 2) < in.size()) {
+      result += kAlphabet[(value >>  0) & 0x3f];
+    } else {
+      result += '=';
+    }
+  }
+
+  return result;
+}
+
+// Post-process the result of SimpleFtoa/SimpleDtoa to *exactly* match the
+// original codegen's formatting (which is just .toString() on java.lang.Double
+// or java.lang.Float).
+string PostProcessFloat(string result) {
+  // If inf, -inf or nan, replace with +Infinity, -Infinity or NaN.
+  if (result == "inf") {
+    return "Infinity";
+  } else if (result == "-inf") {
+    return "-Infinity";
+  } else if (result == "nan") {
+    return "NaN";
+  }
+
+  // If scientific notation (e.g., "1e10"), (i) capitalize the "e", (ii)
+  // ensure that the mantissa (portion prior to the "e") has at least one
+  // fractional digit (after the decimal point), and (iii) strip any unnecessary
+  // leading zeroes and/or '+' signs from the exponent.
+  string::size_type exp_pos = result.find('e');
+  if (exp_pos != string::npos) {
+    string mantissa = result.substr(0, exp_pos);
+    string exponent = result.substr(exp_pos + 1);
+
+    // Add ".0" to mantissa if no fractional part exists.
+    if (mantissa.find('.') == string::npos) {
+      mantissa += ".0";
+    }
+
+    // Strip the sign off the exponent and store as |exp_neg|.
+    bool exp_neg = false;
+    if (!exponent.empty() && exponent[0] == '+') {
+      exponent = exponent.substr(1);
+    } else if (!exponent.empty() && exponent[0] == '-') {
+      exp_neg = true;
+      exponent = exponent.substr(1);
+    }
+
+    // Strip any leading zeroes off the exponent.
+    while (exponent.size() > 1 && exponent[0] == '0') {
+      exponent = exponent.substr(1);
+    }
+
+    return mantissa + "E" + string(exp_neg ? "-" : "") + exponent;
+  }
+
+  // Otherwise, this is an ordinary decimal number. Append ".0" if result has no
+  // decimal/fractional part in order to match output of original codegen.
+  if (result.find('.') == string::npos) {
+    result += ".0";
+  }
+
+  return result;
+}
+
+string FloatToString(float value) {
+  string result = SimpleFtoa(value);
+  return PostProcessFloat(result);
+}
+
+string DoubleToString(double value) {
+  string result = SimpleDtoa(value);
+  return PostProcessFloat(result);
+}
+
+string MaybeNumberString(const FieldDescriptor* field, const string& orig) {
+  return orig;
+}
+
+string JSFieldDefault(const FieldDescriptor* field) {
+  assert(field->has_default_value());
+  switch (field->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+      return MaybeNumberString(
+          field, SimpleItoa(field->default_value_int32()));
+    case FieldDescriptor::CPPTYPE_UINT32:
+      // The original codegen is in Java, and Java protobufs store unsigned
+      // integer values as signed integer values. In order to exactly match the
+      // output, we need to reinterpret as base-2 signed. Ugh.
+      return MaybeNumberString(
+          field, SimpleItoa(static_cast<int32>(field->default_value_uint32())));
+    case FieldDescriptor::CPPTYPE_INT64:
+      return MaybeNumberString(
+          field, SimpleItoa(field->default_value_int64()));
+    case FieldDescriptor::CPPTYPE_UINT64:
+      // See above note for uint32 -- reinterpreting as signed.
+      return MaybeNumberString(
+          field, SimpleItoa(static_cast<int64>(field->default_value_uint64())));
+    case FieldDescriptor::CPPTYPE_ENUM:
+      return SimpleItoa(field->default_value_enum()->number());
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return field->default_value_bool() ? "true" : "false";
+    case FieldDescriptor::CPPTYPE_FLOAT:
+      return FloatToString(field->default_value_float());
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return DoubleToString(field->default_value_double());
+    case FieldDescriptor::CPPTYPE_STRING:
+      if (field->type() == FieldDescriptor::TYPE_STRING) {
+        return "\"" + EscapeJSString(field->default_value_string(), true) +
+               "\"";
+      } else {
+        return "\"" + EscapeBase64(field->default_value_string()) +
+               "\"";
+      }
+    case FieldDescriptor::CPPTYPE_MESSAGE:
+      return "null";
+  }
+}
+
+string ProtoTypeName(const GeneratorOptions& options,
+                     const FieldDescriptor* field) {
+  switch (field->type()) {
+    case FieldDescriptor::TYPE_BOOL:
+      return "bool";
+    case FieldDescriptor::TYPE_INT32:
+      return "int32";
+    case FieldDescriptor::TYPE_UINT32:
+      return "uint32";
+    case FieldDescriptor::TYPE_SINT32:
+      return "sint32";
+    case FieldDescriptor::TYPE_FIXED32:
+      return "fixed32";
+    case FieldDescriptor::TYPE_SFIXED32:
+      return "sfixed32";
+    case FieldDescriptor::TYPE_INT64:
+      return "int64";
+    case FieldDescriptor::TYPE_UINT64:
+      return "uint64";
+    case FieldDescriptor::TYPE_SINT64:
+      return "sint64";
+    case FieldDescriptor::TYPE_FIXED64:
+      return "fixed64";
+    case FieldDescriptor::TYPE_SFIXED64:
+      return "sfixed64";
+    case FieldDescriptor::TYPE_FLOAT:
+      return "float";
+    case FieldDescriptor::TYPE_DOUBLE:
+      return "double";
+    case FieldDescriptor::TYPE_STRING:
+      return "string";
+    case FieldDescriptor::TYPE_BYTES:
+      return "bytes";
+    case FieldDescriptor::TYPE_GROUP:
+      return GetPath(options, field->message_type());
+    case FieldDescriptor::TYPE_ENUM:
+      return GetPath(options, field->enum_type());
+    case FieldDescriptor::TYPE_MESSAGE:
+      return GetPath(options, field->message_type());
+    default:
+      return "";
+  }
+}
+
+string JSIntegerTypeName(const FieldDescriptor* field) {
+  return "number";
+}
+
+string JSTypeName(const GeneratorOptions& options,
+                  const FieldDescriptor* field) {
+  switch (field->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return "boolean";
+    case FieldDescriptor::CPPTYPE_INT32:
+      return JSIntegerTypeName(field);
+    case FieldDescriptor::CPPTYPE_INT64:
+      return JSIntegerTypeName(field);
+    case FieldDescriptor::CPPTYPE_UINT32:
+      return JSIntegerTypeName(field);
+    case FieldDescriptor::CPPTYPE_UINT64:
+      return JSIntegerTypeName(field);
+    case FieldDescriptor::CPPTYPE_FLOAT:
+      return "number";
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return "number";
+    case FieldDescriptor::CPPTYPE_STRING:
+      return "string";
+    case FieldDescriptor::CPPTYPE_ENUM:
+      return GetPath(options, field->enum_type());
+    case FieldDescriptor::CPPTYPE_MESSAGE:
+      return GetPath(options, field->message_type());
+    default:
+      return "";
+  }
+}
+
+bool HasFieldPresence(const FieldDescriptor* field);
+
+string JSFieldTypeAnnotation(const GeneratorOptions& options,
+                             const FieldDescriptor* field,
+                             bool force_optional,
+                             bool force_present,
+                             bool singular_if_not_packed,
+                             bool always_singular) {
+  bool is_primitive =
+      (field->cpp_type() != FieldDescriptor::CPPTYPE_ENUM &&
+       field->cpp_type() != FieldDescriptor::CPPTYPE_MESSAGE);
+
+  string jstype = JSTypeName(options, field);
+
+  if (field->is_repeated() &&
+      !always_singular &&
+      (field->is_packed() || !singular_if_not_packed)) {
+    if (!is_primitive) {
+      jstype = "!" + jstype;
+    }
+    jstype = "Array.<" + jstype + ">";
+    if (!force_optional) {
+      jstype = "!" + jstype;
+    }
+  }
+
+  if (field->is_optional() && is_primitive &&
+      (!field->has_default_value() || force_optional) && !force_present) {
+    jstype += "?";
+  } else if (field->is_required() && !is_primitive && !force_optional) {
+    jstype = "!" + jstype;
+  }
+
+  if (force_optional && HasFieldPresence(field)) {
+    jstype += "|undefined";
+  }
+  if (force_present && jstype[0] != '!' && !is_primitive) {
+    jstype = "!" + jstype;
+  }
+
+  return jstype;
+}
+
+string JSBinaryReaderMethodType(const FieldDescriptor* field) {
+  string name = field->type_name();
+  if (name[0] >= 'a' && name[0] <= 'z') {
+    name[0] = (name[0] - 'a') + 'A';
+  }
+
+  return name;
+}
+
+string JSBinaryReadWriteMethodName(const FieldDescriptor* field,
+                                   bool is_writer) {
+  string name = JSBinaryReaderMethodType(field);
+  if (is_writer && field->type() == FieldDescriptor::TYPE_BYTES) {
+    // Override for `bytes` fields: treat string as raw bytes, not base64.
+    name = "BytesRawString";
+  }
+  if (field->is_packed()) {
+    name = "Packed" + name;
+  } else if (is_writer && field->is_repeated()) {
+    name = "Repeated" + name;
+  }
+  return name;
+}
+
+string JSBinaryReaderMethodName(const FieldDescriptor* field) {
+  return "read" + JSBinaryReadWriteMethodName(field, /* is_writer = */ false);
+}
+
+string JSBinaryWriterMethodName(const FieldDescriptor* field) {
+  return "write" + JSBinaryReadWriteMethodName(field, /* is_writer = */ true);
+}
+
+string JSReturnClause(const FieldDescriptor* desc) {
+  return "";
+}
+
+string JSReturnDoc(const GeneratorOptions& options,
+                   const FieldDescriptor* desc) {
+  return "";
+}
+
+bool HasRepeatedFields(const Descriptor* desc) {
+  for (int i = 0; i < desc->field_count(); i++) {
+    if (desc->field(i)->is_repeated()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static const char* kRepeatedFieldArrayName = ".repeatedFields_";
+
+string RepeatedFieldsArrayName(const GeneratorOptions& options,
+                               const Descriptor* desc) {
+  return HasRepeatedFields(desc) ?
+      (GetPath(options, desc) + kRepeatedFieldArrayName) : "null";
+}
+
+bool HasOneofFields(const Descriptor* desc) {
+  for (int i = 0; i < desc->field_count(); i++) {
+    if (desc->field(i)->containing_oneof()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static const char* kOneofGroupArrayName = ".oneofGroups_";
+
+string OneofFieldsArrayName(const GeneratorOptions& options,
+                            const Descriptor* desc) {
+  return HasOneofFields(desc) ?
+      (GetPath(options, desc) + kOneofGroupArrayName) : "null";
+}
+
+string RepeatedFieldNumberList(const Descriptor* desc) {
+  std::vector<string> numbers;
+  for (int i = 0; i < desc->field_count(); i++) {
+    if (desc->field(i)->is_repeated()) {
+      numbers.push_back(JSFieldIndex(desc->field(i)));
+    }
+  }
+  return "[" + Join(numbers, ",") + "]";
+}
+
+string OneofGroupList(const Descriptor* desc) {
+  // List of arrays (one per oneof), each of which is a list of field indices
+  std::vector<string> oneof_entries;
+  for (int i = 0; i < desc->oneof_decl_count(); i++) {
+    const OneofDescriptor* oneof = desc->oneof_decl(i);
+    if (IgnoreOneof(oneof)) {
+      continue;
+    }
+
+    std::vector<string> oneof_fields;
+    for (int j = 0; j < oneof->field_count(); j++) {
+      if (IgnoreField(oneof->field(j))) {
+        continue;
+      }
+      oneof_fields.push_back(JSFieldIndex(oneof->field(j)));
+    }
+    oneof_entries.push_back("[" + Join(oneof_fields, ",") + "]");
+  }
+  return "[" + Join(oneof_entries, ",") + "]";
+}
+
+string JSOneofArray(const GeneratorOptions& options,
+                    const FieldDescriptor* field) {
+  return OneofFieldsArrayName(options, field->containing_type()) + "[" +
+      JSOneofIndex(field->containing_oneof()) + "]";
+}
+
+string RelativeTypeName(const FieldDescriptor* field) {
+  assert(field->cpp_type() == FieldDescriptor::CPPTYPE_ENUM ||
+         field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE);
+  // For a field with an enum or message type, compute a name relative to the
+  // path name of the message type containing this field.
+  string package = field->file()->package();
+  string containing_type = field->containing_type()->full_name() + ".";
+  string type = (field->cpp_type() == FieldDescriptor::CPPTYPE_ENUM) ?
+      field->enum_type()->full_name() : field->message_type()->full_name();
+
+  // |prefix| is advanced as we find separators '.' past the common package
+  // prefix that yield common prefixes in the containing type's name and this
+  // type's name.
+  int prefix = 0;
+  for (int i = 0; i < type.size() && i < containing_type.size(); i++) {
+    if (type[i] != containing_type[i]) {
+      break;
+    }
+    if (type[i] == '.' && i >= package.size()) {
+      prefix = i + 1;
+    }
+  }
+
+  return type.substr(prefix);
+}
+
+string JSExtensionsObjectName(const GeneratorOptions& options,
+                              const Descriptor* desc) {
+  if (desc->full_name() == "google.protobuf.bridge.MessageSet") {
+    return "jspb.Message.messageSetExtensions";
+  } else {
+    return GetPath(options, desc) + ".extensions";
+  }
+}
+
+string FieldDefinition(const GeneratorOptions& options,
+                       const FieldDescriptor* field) {
+  string qualifier = field->is_repeated() ? "repeated" :
+      (field->is_optional() ? "optional" : "required");
+  string type, name;
+  if (field->type() == FieldDescriptor::TYPE_ENUM ||
+      field->type() == FieldDescriptor::TYPE_MESSAGE) {
+    type = RelativeTypeName(field);
+    name = field->name();
+  } else if (field->type() == FieldDescriptor::TYPE_GROUP) {
+    type = "group";
+    name = field->message_type()->name();
+  } else {
+    type = ProtoTypeName(options, field);
+    name = field->name();
+  }
+  return StringPrintf("%s %s %s = %d;",
+                      qualifier.c_str(),
+                      type.c_str(),
+                      name.c_str(),
+                      field->number());
+}
+
+string FieldComments(const FieldDescriptor* field) {
+  string comments;
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_BOOL) {
+    comments +=
+        " * Note that Boolean fields may be set to 0/1 when serialized from "
+        "a Java server.\n"
+        " * You should avoid comparisons like {@code val === true/false} in "
+        "those cases.\n";
+  }
+  if (field->is_repeated()) {
+    comments +=
+        " * If you change this array by adding, removing or replacing "
+        "elements, or if you\n"
+        " * replace the array itself, then you must call the setter to "
+        "update it.\n";
+  }
+  return comments;
+}
+
+bool ShouldGenerateExtension(const FieldDescriptor* field) {
+  return
+      field->is_extension() &&
+      !IgnoreField(field);
+}
+
+bool HasExtensions(const Descriptor* desc) {
+  if (desc->extension_count() > 0) {
+    return true;
+  }
+  for (int i = 0; i < desc->nested_type_count(); i++) {
+    if (HasExtensions(desc->nested_type(i))) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool HasExtensions(const FileDescriptor* file) {
+  for (int i = 0; i < file->extension_count(); i++) {
+    if (ShouldGenerateExtension(file->extension(i))) {
+      return true;
+    }
+  }
+  for (int i = 0; i < file->message_type_count(); i++) {
+    if (HasExtensions(file->message_type(i))) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool IsExtendable(const Descriptor* desc) {
+  return desc->extension_range_count() > 0;
+}
+
+// Returns the max index in the underlying data storage array beyond which the
+// extension object is used.
+string GetPivot(const Descriptor* desc) {
+  static const int kDefaultPivot = (1 << 29);  // max field number (29 bits)
+
+  // Find the max field number
+  int max_field_number = 0;
+  for (int i = 0; i < desc->field_count(); i++) {
+    if (!IgnoreField(desc->field(i)) &&
+        desc->field(i)->number() > max_field_number) {
+      max_field_number = desc->field(i)->number();
+    }
+  }
+
+  int pivot = -1;
+  if (IsExtendable(desc)) {
+    pivot = ((max_field_number + 1) < kDefaultPivot) ?
+        (max_field_number + 1) : kDefaultPivot;
+  }
+
+  return SimpleItoa(pivot);
+}
+
+// Returns true for fields that represent "null" as distinct from the default
+// value. See https://go/proto3#heading=h.kozewqqcqhuz for more information.
+bool HasFieldPresence(const FieldDescriptor* field) {
+  return
+      (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) ||
+      (field->containing_oneof() != NULL) ||
+      (field->file()->syntax() != FileDescriptor::SYNTAX_PROTO3);
+}
+
+// For proto3 fields without presence, returns a string representing the default
+// value in JavaScript. See https://go/proto3#heading=h.kozewqqcqhuz for more
+// information.
+string Proto3PrimitiveFieldDefault(const FieldDescriptor* field) {
+  switch (field->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+    case FieldDescriptor::CPPTYPE_INT64:
+    case FieldDescriptor::CPPTYPE_UINT32:
+    case FieldDescriptor::CPPTYPE_UINT64: {
+      return "0";
+    }
+
+    case FieldDescriptor::CPPTYPE_ENUM:
+    case FieldDescriptor::CPPTYPE_FLOAT:
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return "0";
+
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return "false";
+
+    case FieldDescriptor::CPPTYPE_STRING:
+      return "\"\"";
+
+    default:
+      // BYTES and MESSAGE are handled separately.
+      assert(false);
+      return "";
+  }
+}
+
+}  // anonymous namespace
+
+void Generator::GenerateHeader(const GeneratorOptions& options,
+                               io::Printer* printer) const {
+  printer->Print("/**\n"
+                 " * @fileoverview\n"
+                 " * @enhanceable\n"
+                 " * @public\n"
+                 " */\n"
+                 "// GENERATED CODE -- DO NOT EDIT!\n"
+                 "\n");
+}
+
+void Generator::FindProvides(const GeneratorOptions& options,
+                             io::Printer* printer,
+                             const vector<const FileDescriptor*>& files,
+                             std::set<string>* provided) const {
+  for (int i = 0; i < files.size(); i++) {
+    for (int j = 0; j < files[i]->message_type_count(); j++) {
+      FindProvidesForMessage(options, printer, files[i]->message_type(j),
+                                 provided);
+    }
+    for (int j = 0; j < files[i]->enum_type_count(); j++) {
+      FindProvidesForEnum(options, printer, files[i]->enum_type(j),
+                              provided);
+    }
+  }
+
+  printer->Print("\n");
+}
+
+void Generator::FindProvidesForMessage(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const Descriptor* desc,
+    std::set<string>* provided) const {
+  string name = GetPath(options, desc);
+  provided->insert(name);
+
+  for (int i = 0; i < desc->enum_type_count(); i++) {
+    FindProvidesForEnum(options, printer, desc->enum_type(i),
+                        provided);
+  }
+  for (int i = 0; i < desc->nested_type_count(); i++) {
+    FindProvidesForMessage(options, printer, desc->nested_type(i),
+                           provided);
+  }
+}
+
+void Generator::FindProvidesForEnum(const GeneratorOptions& options,
+                                    io::Printer* printer,
+                                    const EnumDescriptor* enumdesc,
+                                    std::set<string>* provided) const {
+  string name = GetPath(options, enumdesc);
+  provided->insert(name);
+}
+
+void Generator::FindProvidesForFields(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const vector<const FieldDescriptor*>& fields,
+    std::set<string>* provided) const {
+  for (int i = 0; i < fields.size(); i++) {
+    const FieldDescriptor* field = fields[i];
+
+    if (IgnoreField(field)) {
+      continue;
+    }
+
+    string name =
+        GetPath(options, field->file()) + "." + JSObjectFieldName(field);
+    provided->insert(name);
+  }
+}
+
+void Generator::GenerateProvides(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 std::set<string>* provided) const {
+  for (std::set<string>::iterator it = provided->begin();
+       it != provided->end(); ++it) {
+    printer->Print("goog.provide('$name$');\n",
+                   "name", *it);
+  }
+}
+
+void Generator::GenerateRequires(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 const Descriptor* desc,
+                                 std::set<string>* provided) const {
+  std::set<string> required;
+  std::set<string> forwards;
+  bool have_message = false;
+  FindRequiresForMessage(options, desc,
+                         &required, &forwards, &have_message);
+
+  GenerateRequiresImpl(options, printer, &required, &forwards, provided,
+                       /* require_jspb = */ have_message,
+                       /* require_extension = */ HasExtensions(desc));
+}
+
+void Generator::GenerateRequires(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 const vector<const FileDescriptor*>& files,
+                                 std::set<string>* provided) const {
+  std::set<string> required;
+  std::set<string> forwards;
+  bool have_extensions = false;
+  bool have_message = false;
+
+  for (int i = 0; i < files.size(); i++) {
+    for (int j = 0; j < files[i]->message_type_count(); j++) {
+      FindRequiresForMessage(options,
+                             files[i]->message_type(j),
+                             &required, &forwards, &have_message);
+    }
+    if (!have_extensions && HasExtensions(files[i])) {
+      have_extensions = true;
+    }
+
+    for (int j = 0; j < files[i]->extension_count(); j++) {
+      const FieldDescriptor* extension = files[i]->extension(j);
+      if (IgnoreField(extension)) {
+        continue;
+      }
+      if (extension->containing_type()->full_name() !=
+          "google.protobuf.bridge.MessageSet") {
+        required.insert(GetPath(options, extension->containing_type()));
+      }
+      FindRequiresForField(options, extension, &required, &forwards);
+      have_extensions = true;
+    }
+  }
+
+  GenerateRequiresImpl(options, printer, &required, &forwards, provided,
+                       /* require_jspb = */ have_message,
+                       /* require_extension = */ have_extensions);
+}
+
+void Generator::GenerateRequires(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 const vector<const FieldDescriptor*>& fields,
+                                 std::set<string>* provided) const {
+  std::set<string> required;
+  std::set<string> forwards;
+  for (int i = 0; i < fields.size(); i++) {
+    const FieldDescriptor* field = fields[i];
+    if (IgnoreField(field)) {
+      continue;
+    }
+    FindRequiresForExtension(options, field, &required, &forwards);
+  }
+
+  GenerateRequiresImpl(options, printer, &required, &forwards, provided,
+                       /* require_jspb = */ false,
+                       /* require_extension = */ fields.size() > 0);
+}
+
+void Generator::GenerateRequiresImpl(const GeneratorOptions& options,
+                                     io::Printer* printer,
+                                     std::set<string>* required,
+                                     std::set<string>* forwards,
+                                     std::set<string>* provided,
+                                     bool require_jspb,
+                                     bool require_extension) const {
+  if (require_jspb) {
+    printer->Print(
+        "goog.require('jspb.Message');\n");
+    if (options.binary) {
+      printer->Print(
+          "goog.require('jspb.BinaryReader');\n"
+          "goog.require('jspb.BinaryWriter');\n");
+    }
+  }
+  if (require_extension) {
+    printer->Print(
+        "goog.require('jspb.ExtensionFieldInfo');\n");
+  }
+
+  std::set<string>::iterator it;
+  for (it = required->begin(); it != required->end(); ++it) {
+    if (provided->find(*it) != provided->end()) {
+      continue;
+    }
+    printer->Print("goog.require('$name$');\n",
+                   "name", *it);
+  }
+
+  printer->Print("\n");
+
+  for (it = forwards->begin(); it != forwards->end(); ++it) {
+    if (provided->find(*it) != provided->end()) {
+      continue;
+    }
+    printer->Print("goog.forwardDeclare('$name$');\n",
+                   "name", *it);
+  }
+}
+
+bool NamespaceOnly(const Descriptor* desc) {
+  return false;
+}
+
+void Generator::FindRequiresForMessage(
+    const GeneratorOptions& options,
+    const Descriptor* desc,
+    std::set<string>* required,
+    std::set<string>* forwards,
+    bool* have_message) const {
+
+
+  if (!NamespaceOnly(desc)) {
+    *have_message = true;
+    for (int i = 0; i < desc->field_count(); i++) {
+      const FieldDescriptor* field = desc->field(i);
+      if (IgnoreField(field)) {
+        continue;
+      }
+      FindRequiresForField(options, field, required, forwards);
+    }
+  }
+
+  for (int i = 0; i < desc->extension_count(); i++) {
+    const FieldDescriptor* field = desc->extension(i);
+    if (IgnoreField(field)) {
+      continue;
+    }
+    FindRequiresForExtension(options, field, required, forwards);
+  }
+
+  for (int i = 0; i < desc->nested_type_count(); i++) {
+    FindRequiresForMessage(options, desc->nested_type(i), required, forwards,
+                           have_message);
+  }
+}
+
+void Generator::FindRequiresForField(const GeneratorOptions& options,
+                                     const FieldDescriptor* field,
+                                     std::set<string>* required,
+                                     std::set<string>* forwards) const {
+    if (field->cpp_type() == FieldDescriptor::CPPTYPE_ENUM &&
+        // N.B.: file-level extensions with enum type do *not* create
+        // dependencies, as per original codegen.
+        !(field->is_extension() && field->extension_scope() == NULL)) {
+      if (options.add_require_for_enums) {
+        required->insert(GetPath(options, field->enum_type()));
+      } else {
+        forwards->insert(GetPath(options, field->enum_type()));
+      }
+    } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+      required->insert(GetPath(options, field->message_type()));
+    }
+}
+
+void Generator::FindRequiresForExtension(const GeneratorOptions& options,
+                                         const FieldDescriptor* field,
+                                         std::set<string>* required,
+                                         std::set<string>* forwards) const {
+    if (field->containing_type()->full_name() != "google.protobuf.bridge.MessageSet") {
+      required->insert(GetPath(options, field->containing_type()));
+    }
+    FindRequiresForField(options, field, required, forwards);
+}
+
+void Generator::GenerateTestOnly(const GeneratorOptions& options,
+                                 io::Printer* printer) const {
+  if (options.testonly) {
+    printer->Print("goog.setTestOnly();\n\n");
+  }
+  printer->Print("\n");
+}
+
+void Generator::GenerateClassesAndEnums(const GeneratorOptions& options,
+                                        io::Printer* printer,
+                                        const FileDescriptor* file) const {
+  for (int i = 0; i < file->message_type_count(); i++) {
+    GenerateClass(options, printer, file->message_type(i));
+  }
+  for (int i = 0; i < file->enum_type_count(); i++) {
+    GenerateEnum(options, printer, file->enum_type(i));
+  }
+}
+
+void Generator::GenerateClass(const GeneratorOptions& options,
+                              io::Printer* printer,
+                              const Descriptor* desc) const {
+  if (!NamespaceOnly(desc)) {
+    printer->Print("\n");
+    GenerateClassConstructor(options, printer, desc);
+    GenerateClassFieldInfo(options, printer, desc);
+
+
+    GenerateClassToObject(options, printer, desc);
+    if (options.binary) {
+      // These must come *before* the extension-field info generation in
+      // GenerateClassRegistration so that references to the binary
+      // serialization/deserialization functions may be placed in the extension
+      // objects.
+      GenerateClassDeserializeBinary(options, printer, desc);
+      GenerateClassSerializeBinary(options, printer, desc);
+    }
+    GenerateClassClone(options, printer, desc);
+    GenerateClassRegistration(options, printer, desc);
+    GenerateClassFields(options, printer, desc);
+    if (IsExtendable(desc) && desc->full_name() != "google.protobuf.bridge.MessageSet") {
+      GenerateClassExtensionFieldInfo(options, printer, desc);
+    }
+  }
+
+  // Recurse on nested types.
+  for (int i = 0; i < desc->enum_type_count(); i++) {
+    GenerateEnum(options, printer, desc->enum_type(i));
+  }
+  for (int i = 0; i < desc->nested_type_count(); i++) {
+    GenerateClass(options, printer, desc->nested_type(i));
+  }
+}
+
+void Generator::GenerateClassConstructor(const GeneratorOptions& options,
+                                         io::Printer* printer,
+                                         const Descriptor* desc) const {
+  printer->Print(
+      "/**\n"
+      " * Generated by JsPbCodeGenerator.\n"
+      " * @param {Array=} opt_data Optional initial data array, typically "
+      "from a\n"
+      " * server response, or constructed directly in Javascript. The array "
+      "is used\n"
+      " * in place and becomes part of the constructed object. It is not "
+      "cloned.\n"
+      " * If no data is provided, the constructed object will be empty, but "
+      "still\n"
+      " * valid.\n"
+      " * @extends {jspb.Message}\n"
+      " * @constructor\n"
+      " */\n"
+      "$classname$ = function(opt_data) {\n",
+      "classname", GetPath(options, desc));
+  string message_id = GetMessageId(desc);
+  printer->Print(
+      "  jspb.Message.initialize(this, opt_data, $messageId$, $pivot$, "
+      "$rptfields$, $oneoffields$);\n",
+      "messageId", !message_id.empty() ?
+                   ("'" + message_id + "'") :
+                   (IsResponse(desc) ? "''" : "0"),
+      "pivot", GetPivot(desc),
+      "rptfields", RepeatedFieldsArrayName(options, desc),
+      "oneoffields", OneofFieldsArrayName(options, desc));
+  printer->Print(
+      "};\n"
+      "goog.inherits($classname$, jspb.Message);\n"
+      "if (goog.DEBUG && !COMPILED) {\n"
+      "  $classname$.displayName = '$classname$';\n"
+      "}\n",
+      "classname", GetPath(options, desc));
+}
+
+void Generator::GenerateClassFieldInfo(const GeneratorOptions& options,
+                                       io::Printer* printer,
+                                       const Descriptor* desc) const {
+  if (HasRepeatedFields(desc)) {
+    printer->Print(
+        "/**\n"
+        " * List of repeated fields within this message type.\n"
+        " * @private {!Array<number>}\n"
+        " * @const\n"
+        " */\n"
+        "$classname$$rptfieldarray$ = $rptfields$;\n"
+        "\n",
+        "classname", GetPath(options, desc),
+        "rptfieldarray", kRepeatedFieldArrayName,
+        "rptfields", RepeatedFieldNumberList(desc));
+  }
+
+  if (HasOneofFields(desc)) {
+    printer->Print(
+        "/**\n"
+        " * Oneof group definitions for this message. Each group defines the "
+        "field\n"
+        " * numbers belonging to that group. When of these fields' value is "
+        "set, all\n"
+        " * other fields in the group are cleared. During deserialization, if "
+        "multiple\n"
+        " * fields are encountered for a group, only the last value seen will "
+        "be kept.\n"
+        " * @private {!Array<!Array<number>>}\n"
+        " * @const\n"
+        " */\n"
+        "$classname$$oneofgrouparray$ = $oneofgroups$;\n"
+        "\n",
+        "classname", GetPath(options, desc),
+        "oneofgrouparray", kOneofGroupArrayName,
+        "oneofgroups", OneofGroupList(desc));
+
+    for (int i = 0; i < desc->oneof_decl_count(); i++) {
+      if (IgnoreOneof(desc->oneof_decl(i))) {
+        continue;
+      }
+      GenerateOneofCaseDefinition(options, printer, desc->oneof_decl(i));
+    }
+  }
+}
+
+void Generator::GenerateClassXid(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 const Descriptor* desc) const {
+  printer->Print(
+      "\n"
+      "\n"
+      "$class$.prototype.messageXid = xid('$class$');\n",
+      "class", GetPath(options, desc));
+}
+
+void Generator::GenerateOneofCaseDefinition(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const OneofDescriptor* oneof) const {
+  printer->Print(
+      "/**\n"
+      " * @enum {number}\n"
+      " */\n"
+      "$classname$.$oneof$Case = {\n"
+      "  $upcase$_NOT_SET: 0",
+      "classname", GetPath(options, oneof->containing_type()),
+      "oneof", JSOneofName(oneof),
+      "upcase", ToEnumCase(oneof->name()));
+
+  for (int i = 0; i < oneof->field_count(); i++) {
+    if (IgnoreField(oneof->field(i))) {
+      continue;
+    }
+
+    printer->Print(
+        ",\n"
+        "  $upcase$: $number$",
+        "upcase", ToEnumCase(oneof->field(i)->name()),
+        "number", JSFieldIndex(oneof->field(i)));
+  }
+
+  printer->Print(
+      "\n"
+      "};\n"
+      "\n"
+      "/**\n"
+      " * @return {$class$.$oneof$Case}\n"
+      " */\n"
+      "$class$.prototype.get$oneof$Case = function() {\n"
+      "  return /** @type {$class$.$oneof$Case} */(jspb.Message."
+      "computeOneofCase(this, $class$.oneofGroups_[$oneofindex$]));\n"
+      "};\n"
+      "\n",
+      "class", GetPath(options, oneof->containing_type()),
+      "oneof", JSOneofName(oneof),
+      "oneofindex", JSOneofIndex(oneof));
+}
+
+void Generator::GenerateClassToObject(const GeneratorOptions& options,
+                                      io::Printer* printer,
+                                      const Descriptor* desc) const {
+  printer->Print(
+      "\n"
+      "\n"
+      "if (jspb.Message.GENERATE_TO_OBJECT) {\n"
+      "/**\n"
+      " * Creates an object representation of this proto suitable for use in "
+      "Soy templates.\n"
+      " * Field names that are reserved in JavaScript and will be renamed to "
+      "pb_name.\n"
+      " * To access a reserved field use, foo.pb_<name>, eg, foo.pb_default.\n"
+      " * For the list of reserved names please see:\n"
+      " *     com.google.apps.jspb.JsClassTemplate.JS_RESERVED_WORDS.\n"
+      " * @param {boolean=} opt_includeInstance Whether to include the JSPB "
+      "instance\n"
+      " *     for transitional soy proto support: http://goto/soy-param-"
+      "migration\n"
+      " * @return {!Object}\n"
+      " */\n"
+      "$classname$.prototype.toObject = function(opt_includeInstance) {\n"
+      "  return $classname$.toObject(opt_includeInstance, this);\n"
+      "};\n"
+      "\n"
+      "\n"
+      "/**\n"
+      " * Static version of the {@see toObject} method.\n"
+      " * @param {boolean|undefined} includeInstance Whether to include the "
+      "JSPB\n"
+      " *     instance for transitional soy proto support:\n"
+      " *     http://goto/soy-param-migration\n"
+      " * @param {!$classname$} msg The msg instance to transform.\n"
+      " * @return {!Object}\n"
+      " */\n"
+      "$classname$.toObject = function(includeInstance, msg) {\n"
+      "  var f, obj = {",
+      "classname", GetPath(options, desc));
+
+  bool first = true;
+  for (int i = 0; i < desc->field_count(); i++) {
+    const FieldDescriptor* field = desc->field(i);
+    if (IgnoreField(field)) {
+      continue;
+    }
+
+    if (!first) {
+      printer->Print(",\n    ");
+    } else {
+      printer->Print("\n    ");
+      first = false;
+    }
+
+    GenerateClassFieldToObject(options, printer, field);
+  }
+
+  if (!first) {
+    printer->Print("\n  };\n\n");
+  } else {
+    printer->Print("\n\n  };\n\n");
+  }
+
+  if (IsExtendable(desc)) {
+    printer->Print(
+        "  jspb.Message.toObjectExtension(/** @type {!jspb.Message} */ (msg), "
+        "obj,\n"
+        "      $extObject$, $class$.prototype.getExtension,\n"
+        "      includeInstance);\n",
+        "extObject", JSExtensionsObjectName(options, desc),
+        "class", GetPath(options, desc));
+  }
+
+  printer->Print(
+      "  if (includeInstance) {\n"
+      "    obj.$$jspbMessageInstance = msg\n"
+      "  }\n"
+      "  return obj;\n"
+      "};\n"
+      "}\n"
+      "\n"
+      "\n",
+      "classname", GetPath(options, desc));
+}
+
+void Generator::GenerateClassFieldToObject(const GeneratorOptions& options,
+                                           io::Printer* printer,
+                                           const FieldDescriptor* field) const {
+  printer->Print("$fieldname$: ",
+                 "fieldname", JSObjectFieldName(field));
+
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    // Message field.
+    if (field->is_repeated()) {
+      {
+        printer->Print("jspb.Message.toObjectList(msg.get$getter$(),\n"
+                       "    $type$.toObject, includeInstance)",
+                       "getter", JSGetterName(field),
+                       "type", GetPath(options, field->message_type()));
+      }
+    } else {
+      printer->Print("(f = msg.get$getter$()) && "
+                     "$type$.toObject(includeInstance, f)",
+                     "getter", JSGetterName(field),
+                     "type", GetPath(options, field->message_type()));
+    }
+  } else {
+    // Simple field (singular or repeated).
+    if (!HasFieldPresence(field) && !field->is_repeated()) {
+      // Delegate to the generated get<field>() method in order not to duplicate
+      // the proto3-field-default-value logic here.
+      printer->Print("msg.get$getter$()",
+                     "getter", JSGetterName(field));
+    } else {
+      if (field->has_default_value()) {
+        printer->Print("jspb.Message.getField(msg, $index$) != null ? "
+                       "jspb.Message.getField(msg, $index$) : $defaultValue$",
+                       "index", JSFieldIndex(field),
+                       "defaultValue", JSFieldDefault(field));
+      } else {
+        printer->Print("jspb.Message.getField(msg, $index$)",
+                       "index", JSFieldIndex(field));
+      }
+    }
+  }
+}
+
+void Generator::GenerateClassFromObject(const GeneratorOptions& options,
+                                        io::Printer* printer,
+                                        const Descriptor* desc) const {
+  printer->Print(
+      "if (jspb.Message.GENERATE_FROM_OBJECT) {\n"
+      "/**\n"
+      " * Loads data from an object into a new instance of this proto.\n"
+      " * @param {!Object} obj The object representation of this proto to\n"
+      " *     load the data from.\n"
+      " * @return {!$classname$}\n"
+      " */\n"
+      "$classname$.fromObject = function(obj) {\n"
+      "  var f, msg = new $classname$();\n",
+      "classname", GetPath(options, desc));
+
+  for (int i = 0; i < desc->field_count(); i++) {
+    const FieldDescriptor* field = desc->field(i);
+    GenerateClassFieldFromObject(options, printer, field);
+  }
+
+  printer->Print(
+      "  return msg;\n"
+      "};\n"
+      "}\n");
+}
+
+void Generator::GenerateClassFieldFromObject(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const FieldDescriptor* field) const {
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    // Message field (singular or repeated)
+    if (field->is_repeated()) {
+      {
+        printer->Print(
+            "  goog.isDef(obj.$name$) && "
+            "jspb.Message.setRepeatedWrapperField(\n"
+            "      msg, $index$, goog.array.map(obj.$name$, function(i) {\n"
+            "        return $fieldclass$.fromObject(i);\n"
+            "      }));\n",
+            "name", JSObjectFieldName(field),
+            "index", JSFieldIndex(field),
+            "fieldclass", GetPath(options, field->message_type()));
+      }
+    } else {
+      printer->Print(
+          "  goog.isDef(obj.$name$) && jspb.Message.setWrapperField(\n"
+          "      msg, $index$, $fieldclass$.fromObject(obj.$name$));\n",
+          "name", JSObjectFieldName(field),
+          "index", JSFieldIndex(field),
+          "fieldclass", GetPath(options, field->message_type()));
+    }
+  } else {
+    // Simple (primitive) field.
+    printer->Print(
+        "  goog.isDef(obj.$name$) && jspb.Message.setField(msg, $index$, "
+        "obj.$name$);\n",
+        "name", JSObjectFieldName(field),
+        "index", JSFieldIndex(field));
+  }
+}
+
+void Generator::GenerateClassClone(const GeneratorOptions& options,
+                                   io::Printer* printer,
+                                   const Descriptor* desc) const {
+  printer->Print(
+      "/**\n"
+      " * Creates a deep clone of this proto. No data is shared with the "
+      "original.\n"
+      " * @return {!$name$} The clone.\n"
+      " */\n"
+      "$name$.prototype.cloneMessage = function() {\n"
+      "  return /** @type {!$name$} */ (jspb.Message.cloneMessage(this));\n"
+      "};\n\n\n",
+      "name", GetPath(options, desc));
+}
+
+void Generator::GenerateClassRegistration(const GeneratorOptions& options,
+                                          io::Printer* printer,
+                                          const Descriptor* desc) const {
+  // Register any extensions defined inside this message type.
+  for (int i = 0; i < desc->extension_count(); i++) {
+    const FieldDescriptor* extension = desc->extension(i);
+    if (ShouldGenerateExtension(extension)) {
+      GenerateExtension(options, printer, extension);
+    }
+  }
+
+}
+
+void Generator::GenerateClassFields(const GeneratorOptions& options,
+                                    io::Printer* printer,
+                                    const Descriptor* desc) const {
+  for (int i = 0; i < desc->field_count(); i++) {
+    if (!IgnoreField(desc->field(i))) {
+      GenerateClassField(options, printer, desc->field(i));
+    }
+  }
+}
+
+void Generator::GenerateClassField(const GeneratorOptions& options,
+                                   io::Printer* printer,
+                                   const FieldDescriptor* field) const {
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    printer->Print(
+        "/**\n"
+        " * $fielddef$\n"
+        "$comment$"
+        " * @return {$type$}\n"
+        " */\n",
+        "fielddef", FieldDefinition(options, field),
+        "comment", FieldComments(field),
+        "type", JSFieldTypeAnnotation(options, field,
+                                      /* force_optional = */ false,
+                                      /* force_present = */ false,
+                                      /* singular_if_not_packed = */ false,
+                                      /* always_singular = */ false));
+    printer->Print(
+        "$class$.prototype.get$name$ = function() {\n"
+        "  return /** @type{$type$} */ (\n"
+        "    jspb.Message.get$rpt$WrapperField(this, $wrapperclass$, "
+        "$index$$required$));\n"
+        "};\n"
+        "\n"
+        "\n",
+        "class", GetPath(options, field->containing_type()),
+        "name", JSGetterName(field),
+        "type", JSFieldTypeAnnotation(options, field,
+                                      /* force_optional = */ false,
+                                      /* force_present = */ false,
+                                      /* singular_if_not_packed = */ false,
+                                      /* always_singular = */ false),
+        "rpt", (field->is_repeated() ? "Repeated" : ""),
+        "index", JSFieldIndex(field),
+        "wrapperclass", GetPath(options, field->message_type()),
+        "required", (field->label() == FieldDescriptor::LABEL_REQUIRED ?
+                     ", 1" : ""));
+    printer->Print(
+        "/** @param {$optionaltype$} value $returndoc$ */\n"
+        "$class$.prototype.set$name$ = function(value) {\n"
+        "  jspb.Message.set$oneoftag$$repeatedtag$WrapperField(",
+        "optionaltype",
+        JSFieldTypeAnnotation(options, field,
+                              /* force_optional = */ true,
+                              /* force_present = */ false,
+                              /* singular_if_not_packed = */ false,
+                              /* always_singular = */ false),
+        "returndoc", JSReturnDoc(options, field),
+        "class", GetPath(options, field->containing_type()),
+        "name", JSGetterName(field),
+        "oneoftag", (field->containing_oneof() ? "Oneof" : ""),
+        "repeatedtag", (field->is_repeated() ? "Repeated" : ""));
+
+    printer->Print(
+        "this, $index$$oneofgroup$, value);$returnvalue$\n"
+        "};\n"
+        "\n"
+        "\n",
+        "index", JSFieldIndex(field),
+        "oneofgroup", (field->containing_oneof() ?
+                       (", " + JSOneofArray(options, field)) : ""),
+        "returnvalue", JSReturnClause(field));
+
+    printer->Print(
+        "$class$.prototype.clear$name$ = function() {\n"
+        "  this.set$name$($clearedvalue$);$returnvalue$\n"
+        "};\n"
+        "\n"
+        "\n",
+        "class", GetPath(options, field->containing_type()),
+        "name", JSGetterName(field),
+        "clearedvalue", (field->is_repeated() ? "[]" : "undefined"),
+        "returnvalue", JSReturnClause(field));
+
+  } else {
+    string typed_annotation;
+
+    // Simple (primitive) field, either singular or repeated.
+    {
+      typed_annotation = JSFieldTypeAnnotation(options, field,
+                              /* force_optional = */ false,
+                              /* force_present = */ !HasFieldPresence(field),
+                              /* singular_if_not_packed = */ false,
+                              /* always_singular = */ false),
+      printer->Print(
+          "/**\n"
+          " * $fielddef$\n"
+          "$comment$"
+          " * @return {$type$}\n"
+          " */\n",
+          "fielddef", FieldDefinition(options, field),
+          "comment", FieldComments(field),
+          "type", typed_annotation);
+    }
+
+    printer->Print(
+        "$class$.prototype.get$name$ = function() {\n",
+        "class", GetPath(options, field->containing_type()),
+        "name", JSGetterName(field));
+
+    {
+      printer->Print(
+          "  return /** @type {$type$} */ (",
+          "type", typed_annotation);
+    }
+
+    // For proto3 fields without presence, use special getters that will return
+    // defaults when the field is unset, possibly constructing a value if
+    // required.
+    if (!HasFieldPresence(field) && !field->is_repeated()) {
+      printer->Print("jspb.Message.getFieldProto3(this, $index$, $default$)",
+                     "index", JSFieldIndex(field),
+                     "default", Proto3PrimitiveFieldDefault(field));
+    } else {
+      if (field->has_default_value()) {
+        printer->Print("jspb.Message.getField(this, $index$) != null ? "
+                       "jspb.Message.getField(this, $index$) : $defaultValue$",
+                       "index", JSFieldIndex(field),
+                       "defaultValue", JSFieldDefault(field));
+      } else {
+        printer->Print("jspb.Message.getField(this, $index$)",
+                       "index", JSFieldIndex(field));
+      }
+    }
+
+    {
+      printer->Print(
+          ");\n"
+          "};\n"
+          "\n"
+          "\n");
+    }
+
+    {
+      printer->Print(
+          "/** @param {$optionaltype$} value $returndoc$ */\n",
+          "optionaltype",
+          JSFieldTypeAnnotation(options, field,
+                                /* force_optional = */ true,
+                                /* force_present = */ !HasFieldPresence(field),
+                                /* singular_if_not_packed = */ false,
+                                /* always_singular = */ false),
+          "returndoc", JSReturnDoc(options, field));
+    }
+
+    printer->Print(
+        "$class$.prototype.set$name$ = function(value) {\n"
+        "  jspb.Message.set$oneoftag$Field(this, $index$",
+        "class", GetPath(options, field->containing_type()),
+        "name", JSGetterName(field),
+        "oneoftag", (field->containing_oneof() ? "Oneof" : ""),
+        "index", JSFieldIndex(field));
+    printer->Print(
+        "$oneofgroup$, $type$value$rptvalueinit$$typeclose$);$returnvalue$\n"
+        "};\n"
+        "\n"
+        "\n",
+        "type", "",
+        "typeclose", "",
+        "oneofgroup",
+        (field->containing_oneof() ? (", " + JSOneofArray(options, field))
+                                   : ""),
+        "returnvalue", JSReturnClause(field), "rptvalueinit",
+        (field->is_repeated() ? " || []" : ""));
+
+
+    if (HasFieldPresence(field)) {
+      printer->Print(
+          "$class$.prototype.clear$name$ = function() {\n"
+          "  jspb.Message.set$oneoftag$Field(this, $index$$oneofgroup$, ",
+          "class", GetPath(options, field->containing_type()),
+          "name", JSGetterName(field),
+          "oneoftag", (field->containing_oneof() ? "Oneof" : ""),
+          "oneofgroup", (field->containing_oneof() ?
+                         (", " + JSOneofArray(options, field)) : ""),
+          "index", JSFieldIndex(field));
+      printer->Print(
+          "$clearedvalue$);$returnvalue$\n"
+          "};\n"
+          "\n"
+          "\n",
+          "clearedvalue", (field->is_repeated() ? "[]" : "undefined"),
+          "returnvalue", JSReturnClause(field));
+    }
+  }
+}
+
+void Generator::GenerateClassExtensionFieldInfo(const GeneratorOptions& options,
+                                                io::Printer* printer,
+                                                const Descriptor* desc) const {
+  if (IsExtendable(desc)) {
+    printer->Print(
+        "\n"
+        "/**\n"
+        " * The extensions registered with this message class. This is a "
+        "map of\n"
+        " * extension field number to fieldInfo object.\n"
+        " *\n"
+        " * For example:\n"
+        " *     { 123: {fieldIndex: 123, fieldName: {my_field_name: 0}, "
+        "ctor: proto.example.MyMessage} }\n"
+        " *\n"
+        " * fieldName contains the JsCompiler renamed field name property "
+        "so that it\n"
+        " * works in OPTIMIZED mode.\n"
+        " *\n"
+        " * @type {!Object.<number, jspb.ExtensionFieldInfo>}\n"
+        " */\n"
+        "$class$.extensions = {};\n"
+        "\n",
+        "class", GetPath(options, desc));
+  }
+}
+
+
+void Generator::GenerateClassDeserializeBinary(const GeneratorOptions& options,
+                                               io::Printer* printer,
+                                               const Descriptor* desc) const {
+  // TODO(cfallin): Handle lazy decoding when requested by field option and/or
+  // by default for 'bytes' fields and packed repeated fields.
+
+  printer->Print(
+      "/**\n"
+      " * Deserializes binary data (in protobuf wire format).\n"
+      " * @param {jspb.ByteSource} bytes The bytes to deserialize.\n"
+      " * @return {!$class$}\n"
+      " */\n"
+      "$class$.deserializeBinary = function(bytes) {\n"
+      "  var reader = new jspb.BinaryReader(bytes);\n"
+      "  var msg = new $class$;\n"
+      "  return $class$.deserializeBinaryFromReader(msg, reader);\n"
+      "};\n"
+      "\n"
+      "\n"
+      "/**\n"
+      " * Deserializes binary data (in protobuf wire format) from the\n"
+      " * given reader into the given message object.\n"
+      " * @param {!$class$} msg The message object to deserialize into.\n"
+      " * @param {!jspb.BinaryReader} reader The BinaryReader to use.\n"
+      " * @return {!$class$}\n"
+      " */\n"
+      "$class$.deserializeBinaryFromReader = function(msg, reader) {\n"
+      "  while (reader.nextField()) {\n"
+      "    if (reader.isEndGroup()) {\n"
+      "      break;\n"
+      "    }\n"
+      "    var field = reader.getFieldNumber();\n"
+      "    switch (field) {\n",
+      "class", GetPath(options, desc));
+
+  for (int i = 0; i < desc->field_count(); i++) {
+    GenerateClassDeserializeBinaryField(options, printer, desc->field(i));
+  }
+
+  printer->Print(
+      "    default:\n");
+  if (IsExtendable(desc)) {
+    printer->Print(
+        "      jspb.Message.readBinaryExtension(msg, reader, $extobj$,\n"
+        "        $class$.prototype.getExtension,\n"
+        "        $class$.prototype.setExtension);\n"
+        "      break;\n",
+        "extobj", JSExtensionsObjectName(options, desc),
+        "class", GetPath(options, desc));
+  } else {
+    printer->Print(
+        "      reader.skipField();\n"
+        "      break;\n");
+  }
+
+  printer->Print(
+      "    }\n"
+      "  }\n"
+      "  return msg;\n"
+      "};\n"
+      "\n"
+      "\n");
+}
+
+void Generator::GenerateClassDeserializeBinaryField(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const FieldDescriptor* field) const {
+
+  printer->Print("    case $num$:\n",
+                 "num", SimpleItoa(field->number()));
+
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    printer->Print(
+        "      var value = new $fieldclass$;\n"
+        "      reader.read$msgOrGroup$($grpfield$value,"
+        "$fieldclass$.deserializeBinaryFromReader);\n",
+        "fieldclass", GetPath(options, field->message_type()),
+        "msgOrGroup", (field->type() == FieldDescriptor::TYPE_GROUP) ?
+                      "Group" : "Message",
+        "grpfield", (field->type() == FieldDescriptor::TYPE_GROUP) ?
+                    (SimpleItoa(field->number()) + ", ") : "");
+  } else {
+    printer->Print(
+        "      var value = /** @type {$fieldtype$} */ (reader.$reader$());\n",
+        "fieldtype", JSFieldTypeAnnotation(options, field, false, true,
+                                           /* singular_if_not_packed = */ true,
+                                           /* always_singular = */ false),
+        "reader", JSBinaryReaderMethodName(field));
+  }
+
+  if (field->is_repeated() && !field->is_packed()) {
+    // Repeated fields receive a |value| one at at a time; append to array
+    // returned by get$name$().
+    printer->Print(
+        "      msg.get$name$().push(value);\n",
+        "name", JSGetterName(field));
+  } else {
+    // Singular fields, and packed repeated fields, receive a |value| either as
+    // the field's value or as the array of all the field's values; set this as
+    // the field's value directly.
+    printer->Print(
+        "      msg.set$name$(value);\n",
+        "name", JSGetterName(field));
+  }
+
+  printer->Print("      break;\n");
+}
+
+void Generator::GenerateClassSerializeBinary(const GeneratorOptions& options,
+                                             io::Printer* printer,
+                                             const Descriptor* desc) const {
+  printer->Print(
+      "/**\n"
+      " * Class method variant: serializes the given message to binary data\n"
+      " * (in protobuf wire format), writing to the given BinaryWriter.\n"
+      " * @param {!$class$} message\n"
+      " * @param {!jspb.BinaryWriter} writer\n"
+      " */\n"
+      "$class$.serializeBinaryToWriter = function(message, "
+      "writer) {\n"
+      "  message.serializeBinaryToWriter(writer);\n"
+      "};\n"
+      "\n"
+      "\n"
+      "/**\n"
+      " * Serializes the message to binary data (in protobuf wire format).\n"
+      " * @return {!Uint8Array}\n"
+      " */\n"
+      "$class$.prototype.serializeBinary = function() {\n"
+      "  var writer = new jspb.BinaryWriter();\n"
+      "  this.serializeBinaryToWriter(writer);\n"
+      "  return writer.getResultBuffer();\n"
+      "};\n"
+      "\n"
+      "\n"
+      "/**\n"
+      " * Serializes the message to binary data (in protobuf wire format),\n"
+      " * writing to the given BinaryWriter.\n"
+      " * @param {!jspb.BinaryWriter} writer\n"
+      " */\n"
+      "$class$.prototype.serializeBinaryToWriter = function (writer) {\n"
+      "  var f = undefined;\n",
+      "class", GetPath(options, desc));
+
+  for (int i = 0; i < desc->field_count(); i++) {
+    GenerateClassSerializeBinaryField(options, printer, desc->field(i));
+  }
+
+  if (IsExtendable(desc)) {
+    printer->Print(
+        "  jspb.Message.serializeBinaryExtensions(this, writer, $extobj$,\n"
+        "    $class$.prototype.getExtension);\n",
+        "extobj", JSExtensionsObjectName(options, desc),
+        "class", GetPath(options, desc));
+  }
+
+  printer->Print(
+      "};\n"
+      "\n"
+      "\n");
+}
+
+void Generator::GenerateClassSerializeBinaryField(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const FieldDescriptor* field) const {
+  printer->Print(
+      "  f = this.get$name$();\n",
+      "name", JSGetterName(field));
+
+  if (field->is_repeated()) {
+    printer->Print(
+        "  if (f.length > 0) {\n");
+  } else {
+    if (HasFieldPresence(field)) {
+      printer->Print(
+          "  if (f != null) {\n");
+    } else {
+      // No field presence: serialize onto the wire only if value is
+      // non-default.  Defaults are documented here:
+      // https://goto.google.com/lhdfm
+      switch (field->cpp_type()) {
+        case FieldDescriptor::CPPTYPE_INT32:
+        case FieldDescriptor::CPPTYPE_INT64:
+        case FieldDescriptor::CPPTYPE_UINT32:
+        case FieldDescriptor::CPPTYPE_UINT64: {
+          {
+            printer->Print("  if (f !== 0) {\n");
+          }
+          break;
+        }
+
+        case FieldDescriptor::CPPTYPE_ENUM:
+        case FieldDescriptor::CPPTYPE_FLOAT:
+        case FieldDescriptor::CPPTYPE_DOUBLE:
+          printer->Print(
+              "  if (f !== 0.0) {\n");
+          break;
+        case FieldDescriptor::CPPTYPE_BOOL:
+          printer->Print(
+              "  if (f) {\n");
+          break;
+        case FieldDescriptor::CPPTYPE_STRING:
+          printer->Print(
+              "  if (f.length > 0) {\n");
+          break;
+        default:
+          assert(false);
+          break;
+      }
+    }
+  }
+
+  printer->Print(
+      "    writer.$writer$(\n"
+      "      $index$,\n"
+      "      f",
+      "writer", JSBinaryWriterMethodName(field),
+      "name", JSGetterName(field),
+      "index", SimpleItoa(field->number()));
+
+  if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
+    printer->Print(
+        ",\n"
+        "      $submsg$.serializeBinaryToWriter\n",
+        "submsg", GetPath(options, field->message_type()));
+  } else {
+    printer->Print("\n");
+  }
+  printer->Print(
+      "    );\n"
+      "  }\n");
+}
+
+void Generator::GenerateEnum(const GeneratorOptions& options,
+                             io::Printer* printer,
+                             const EnumDescriptor* enumdesc) const {
+  printer->Print(
+      "/**\n"
+      " * @enum {number}\n"
+      " */\n"
+      "$name$ = {\n",
+      "name", GetPath(options, enumdesc));
+
+  for (int i = 0; i < enumdesc->value_count(); i++) {
+    const EnumValueDescriptor* value = enumdesc->value(i);
+    printer->Print(
+        "  $name$: $value$$comma$\n",
+        "name", ToEnumCase(value->name()),
+        "value", SimpleItoa(value->number()),
+        "comma", (i == enumdesc->value_count() - 1) ? "" : ",");
+  }
+
+  printer->Print(
+      "};\n"
+      "\n");
+}
+
+void Generator::GenerateExtension(const GeneratorOptions& options,
+                                  io::Printer* printer,
+                                  const FieldDescriptor* field) const {
+  string extension_scope =
+      (field->extension_scope() ?
+       GetPath(options, field->extension_scope()) :
+       GetPath(options, field->file()));
+
+  printer->Print(
+      "\n"
+      "/**\n"
+      " * A tuple of {field number, class constructor} for the extension\n"
+      " * field named `$name$`.\n"
+      " * @type {!jspb.ExtensionFieldInfo.<$extensionType$>}\n"
+      " */\n"
+      "$class$.$name$ = new jspb.ExtensionFieldInfo(\n",
+      "name", JSObjectFieldName(field),
+      "class", extension_scope,
+      "extensionType", JSFieldTypeAnnotation(
+          options, field,
+          /* force_optional = */ false,
+          /* force_present = */ true,
+          /* singular_if_not_packed = */ false,
+          /* always_singular = */ false));
+  printer->Print(
+      "    $index$,\n"
+      "    {$name$: 0},\n"
+      "    $ctor$,\n"
+      "     /** @type {?function((boolean|undefined),!jspb.Message=): "
+      "!Object} */ (\n"
+      "         $toObject$),\n"
+      "    $repeated$",
+      "index", SimpleItoa(field->number()),
+      "name", JSObjectFieldName(field),
+      "ctor", (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE ?
+               GetPath(options, field->message_type()) : string("null")),
+      "toObject", (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE ?
+                   (GetPath(options, field->message_type()) + ".toObject") :
+                   string("null")),
+      "repeated", (field->is_repeated() ? "1" : "0"));
+
+  if (options.binary) {
+    printer->Print(
+        ",\n"
+        "    jspb.BinaryReader.prototype.$binaryReaderFn$,\n"
+        "    jspb.BinaryWriter.prototype.$binaryWriterFn$,\n"
+        "    $binaryMessageSerializeFn$,\n"
+        "    $binaryMessageDeserializeFn$,\n"
+        "    $isPacked$);\n",
+        "binaryReaderFn", JSBinaryReaderMethodName(field),
+        "binaryWriterFn", JSBinaryWriterMethodName(field),
+        "binaryMessageSerializeFn",
+        (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) ?
+        (GetPath(options, field->message_type()) +
+         ".serializeBinaryToWriter") : "null",
+        "binaryMessageDeserializeFn",
+        (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) ?
+        (GetPath(options, field->message_type()) +
+         ".deserializeBinaryFromReader") : "null",
+        "isPacked", (field->is_packed() ? "true" : "false"));
+  } else {
+    printer->Print(");\n");
+  }
+
+  printer->Print(
+      "// This registers the extension field with the extended class, so that\n"
+      "// toObject() will function correctly.\n"
+      "$extendName$[$index$] = $class$.$name$;\n"
+      "\n",
+      "extendName", JSExtensionsObjectName(options, field->containing_type()),
+      "index", SimpleItoa(field->number()),
+      "class", extension_scope,
+      "name", JSObjectFieldName(field));
+}
+
+bool GeneratorOptions::ParseFromOptions(
+    const vector< pair< string, string > >& options,
+    string* error) {
+  for (int i = 0; i < options.size(); i++) {
+    if (options[i].first == "add_require_for_enums") {
+      if (options[i].second != "") {
+        *error = "Unexpected option value for add_require_for_enums";
+        return false;
+      }
+      add_require_for_enums = true;
+    } else if (options[i].first == "binary") {
+      if (options[i].second != "") {
+        *error = "Unexpected option value for binary";
+        return false;
+      }
+      binary = true;
+    } else if (options[i].first == "testonly") {
+      if (options[i].second != "") {
+        *error = "Unexpected option value for testonly";
+        return false;
+      }
+      testonly = true;
+    } else if (options[i].first == "error_on_name_conflict") {
+      if (options[i].second != "") {
+        *error = "Unexpected option value for error_on_name_conflict";
+        return false;
+      }
+      error_on_name_conflict = true;
+    } else if (options[i].first == "output_dir") {
+      output_dir = options[i].second;
+    } else if (options[i].first == "namespace_prefix") {
+      namespace_prefix = options[i].second;
+    } else if (options[i].first == "library") {
+      library = options[i].second;
+    } else {
+      // Assume any other option is an output directory, as long as it is a bare
+      // `key` rather than a `key=value` option.
+      if (options[i].second != "") {
+        *error = "Unknown option: " + options[i].first;
+        return false;
+      }
+      output_dir = options[i].first;
+    }
+  }
+
+  return true;
+}
+
+void Generator::GenerateFilesInDepOrder(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const vector<const FileDescriptor*>& files) const {
+  // Build a std::set over all files so that the DFS can detect when it recurses
+  // into a dep not specified in the user's command line.
+  std::set<const FileDescriptor*> all_files(files.begin(), files.end());
+  // Track the in-progress set of files that have been generated already.
+  std::set<const FileDescriptor*> generated;
+  for (int i = 0; i < files.size(); i++) {
+    GenerateFileAndDeps(options, printer, files[i], &all_files, &generated);
+  }
+}
+
+void Generator::GenerateFileAndDeps(
+    const GeneratorOptions& options,
+    io::Printer* printer,
+    const FileDescriptor* root,
+    std::set<const FileDescriptor*>* all_files,
+    std::set<const FileDescriptor*>* generated) const {
+  // Skip if already generated.
+  if (generated->find(root) != generated->end()) {
+    return;
+  }
+  generated->insert(root);
+
+  // Generate all dependencies before this file's content.
+  for (int i = 0; i < root->dependency_count(); i++) {
+    const FileDescriptor* dep = root->dependency(i);
+    GenerateFileAndDeps(options, printer, dep, all_files, generated);
+  }
+
+  // Generate this file's content.  Only generate if the file is part of the
+  // original set requested to be generated; i.e., don't take all transitive
+  // deps down to the roots.
+  if (all_files->find(root) != all_files->end()) {
+    GenerateClassesAndEnums(options, printer, root);
+  }
+}
+
+bool Generator::GenerateAll(const vector<const FileDescriptor*>& files,
+                            const string& parameter,
+                            GeneratorContext* context,
+                            string* error) const {
+  vector< pair< string, string > > option_pairs;
+  ParseGeneratorParameter(parameter, &option_pairs);
+  GeneratorOptions options;
+  if (!options.ParseFromOptions(option_pairs, error)) {
+    return false;
+  }
+
+
+  // We're either generating a single library file with definitions for message
+  // and enum types in *all* FileDescriptor inputs, or we're generating a single
+  // file for each type.
+  if (options.library != "") {
+    string filename = options.output_dir + "/" + options.library + ".js";
+    google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(context->Open(filename));
+    GOOGLE_CHECK(output.get());
+    io::Printer printer(output.get(), '$');
+
+    // Pull out all extensions -- we need these to generate all
+    // provides/requires.
+    vector<const FieldDescriptor*> extensions;
+    for (int i = 0; i < files.size(); i++) {
+      for (int j = 0; j < files[i]->extension_count(); j++) {
+        const FieldDescriptor* extension = files[i]->extension(j);
+        extensions.push_back(extension);
+      }
+    }
+
+    GenerateHeader(options, &printer);
+
+    std::set<string> provided;
+    FindProvides(options, &printer, files, &provided);
+    FindProvidesForFields(options, &printer, extensions, &provided);
+    GenerateProvides(options, &printer, &provided);
+    GenerateTestOnly(options, &printer);
+    GenerateRequires(options, &printer, files, &provided);
+
+    GenerateFilesInDepOrder(options, &printer, files);
+
+    for (int i = 0; i < extensions.size(); i++) {
+      if (ShouldGenerateExtension(extensions[i])) {
+        GenerateExtension(options, &printer, extensions[i]);
+      }
+    }
+
+    if (printer.failed()) {
+      return false;
+    }
+  } else {
+    // Collect all types, and print each type to a separate file. Pull out
+    // free-floating extensions while we make this pass.
+    map< string, vector<const FieldDescriptor*> > extensions_by_namespace;
+
+    // If we're generating code in file-per-type mode, avoid overwriting files
+    // by choosing the last descriptor that writes each filename and permitting
+    // only those to generate code.
+
+    // Current descriptor that will generate each filename, indexed by filename.
+    map<string, const void*> desc_by_filename;
+    // Set of descriptors allowed to generate files.
+    set<const void*> allowed_descs;
+
+    for (int i = 0; i < files.size(); i++) {
+      // Collect all (descriptor, filename) pairs.
+      map<const void*, string> descs_in_file;
+      for (int j = 0; j < files[i]->message_type_count(); j++) {
+        const Descriptor* desc = files[i]->message_type(j);
+        string filename =
+            options.output_dir + "/" + ToFileName(desc->name()) + ".js";
+        descs_in_file[desc] = filename;
+      }
+      for (int j = 0; j < files[i]->enum_type_count(); j++) {
+        const EnumDescriptor* desc = files[i]->enum_type(j);
+        string filename =
+            options.output_dir + "/" + ToFileName(desc->name()) + ".js";
+        descs_in_file[desc] = filename;
+      }
+
+      // For each (descriptor, filename) pair, update the
+      // descriptors-by-filename map, and if a previous descriptor was already
+      // writing the filename, remove it from the allowed-descriptors set.
+      map<const void*, string>::iterator it;
+      for (it = descs_in_file.begin(); it != descs_in_file.end(); ++it) {
+        const void* desc = it->first;
+        const string& filename = it->second;
+        if (desc_by_filename.find(filename) != desc_by_filename.end()) {
+          if (options.error_on_name_conflict) {
+            *error = "Name conflict: file name " + filename +
+                     " would be generated by two descriptors";
+            return false;
+          }
+          allowed_descs.erase(desc_by_filename[filename]);
+        }
+        desc_by_filename[filename] = desc;
+        allowed_descs.insert(desc);
+      }
+    }
+
+    // Generate code.
+    for (int i = 0; i < files.size(); i++) {
+      const FileDescriptor* file = files[i];
+      for (int j = 0; j < file->message_type_count(); j++) {
+        const Descriptor* desc = file->message_type(j);
+        if (allowed_descs.find(desc) == allowed_descs.end()) {
+          continue;
+        }
+
+        string filename = options.output_dir + "/" +
+            ToFileName(desc->name()) + ".js";
+        google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(
+            context->Open(filename));
+        GOOGLE_CHECK(output.get());
+        io::Printer printer(output.get(), '$');
+
+        GenerateHeader(options, &printer);
+
+        std::set<string> provided;
+        FindProvidesForMessage(options, &printer, desc, &provided);
+        GenerateProvides(options, &printer, &provided);
+        GenerateTestOnly(options, &printer);
+        GenerateRequires(options, &printer, desc, &provided);
+
+        GenerateClass(options, &printer, desc);
+
+        if (printer.failed()) {
+          return false;
+        }
+      }
+      for (int j = 0; j < file->enum_type_count(); j++) {
+        const EnumDescriptor* enumdesc = file->enum_type(j);
+        if (allowed_descs.find(enumdesc) == allowed_descs.end()) {
+          continue;
+        }
+
+        string filename = options.output_dir + "/" +
+            ToFileName(enumdesc->name()) + ".js";
+
+        google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(
+            context->Open(filename));
+        GOOGLE_CHECK(output.get());
+        io::Printer printer(output.get(), '$');
+
+        GenerateHeader(options, &printer);
+
+        std::set<string> provided;
+        FindProvidesForEnum(options, &printer, enumdesc, &provided);
+        GenerateProvides(options, &printer, &provided);
+        GenerateTestOnly(options, &printer);
+
+        GenerateEnum(options, &printer, enumdesc);
+
+        if (printer.failed()) {
+          return false;
+        }
+      }
+      // Pull out all free-floating extensions and generate files for those too.
+      for (int j = 0; j < file->extension_count(); j++) {
+        const FieldDescriptor* extension = file->extension(j);
+        extensions_by_namespace[GetPath(options, files[i])]
+            .push_back(extension);
+      }
+    }
+
+    // Generate extensions in separate files.
+    map< string, vector<const FieldDescriptor*> >::iterator it;
+    for (it = extensions_by_namespace.begin();
+         it != extensions_by_namespace.end();
+         ++it) {
+      string filename = options.output_dir + "/" +
+          ToFileName(it->first) + ".js";
+
+      google::protobuf::scoped_ptr<io::ZeroCopyOutputStream> output(
+          context->Open(filename));
+      GOOGLE_CHECK(output.get());
+      io::Printer printer(output.get(), '$');
+
+      GenerateHeader(options, &printer);
+
+      std::set<string> provided;
+      FindProvidesForFields(options, &printer, it->second, &provided);
+      GenerateProvides(options, &printer, &provided);
+      GenerateTestOnly(options, &printer);
+      GenerateRequires(options, &printer, it->second, &provided);
+
+      for (int j = 0; j < it->second.size(); j++) {
+        if (ShouldGenerateExtension(it->second[j])) {
+          GenerateExtension(options, &printer, it->second[j]);
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+}  // namespace js
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/compiler/js/js_generator.h b/src/google/protobuf/compiler/js/js_generator.h
new file mode 100755
index 00000000..db2dceb3
--- /dev/null
+++ b/src/google/protobuf/compiler/js/js_generator.h
@@ -0,0 +1,265 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_JS_GENERATOR_H__
+#define GOOGLE_PROTOBUF_COMPILER_JS_GENERATOR_H__
+
+#include <string>
+#include <set>
+
+#include <google/protobuf/compiler/code_generator.h>
+
+namespace google {
+namespace protobuf {
+
+class Descriptor;
+class EnumDescriptor;
+class FieldDescriptor;
+class OneofDescriptor;
+class FileDescriptor;
+
+namespace io { class Printer; }
+
+namespace compiler {
+namespace js {
+
+struct GeneratorOptions {
+  // Add a `goog.requires()` call for each enum type used. If not set, a forward
+  // declaration with `goog.forwardDeclare` is produced instead.
+  bool add_require_for_enums;
+  // Set this as a test-only module via `goog.setTestOnly();`.
+  bool testonly;
+  // Output path.
+  string output_dir;
+  // Namespace prefix.
+  string namespace_prefix;
+  // Create a library with name <name>_lib.js rather than a separate .js file
+  // per type?
+  string library;
+  // Error if there are two types that would generate the same output file?
+  bool error_on_name_conflict;
+  // Enable binary-format support?
+  bool binary;
+
+  GeneratorOptions()
+      : add_require_for_enums(false),
+        testonly(false),
+        output_dir("."),
+        namespace_prefix(""),
+        library(""),
+        error_on_name_conflict(false),
+        binary(false) {}
+
+  bool ParseFromOptions(
+      const vector< pair< string, string > >& options,
+      string* error);
+};
+
+class LIBPROTOC_EXPORT Generator : public CodeGenerator {
+ public:
+  Generator() {}
+  virtual ~Generator() {}
+
+  virtual bool Generate(const FileDescriptor* file,
+                        const string& parameter,
+                        GeneratorContext* context,
+                        string* error) const {
+    *error = "Unimplemented Generate() method. Call GenerateAll() instead.";
+    return false;
+  }
+
+  virtual bool HasGenerateAll() const { return true; }
+
+  virtual bool GenerateAll(const vector<const FileDescriptor*>& files,
+                           const string& parameter,
+                           GeneratorContext* context,
+                           string* error) const;
+
+ private:
+  void GenerateHeader(const GeneratorOptions& options,
+                      io::Printer* printer) const;
+
+  // Generate goog.provides() calls.
+  void FindProvides(const GeneratorOptions& options,
+                    io::Printer* printer,
+                    const vector<const FileDescriptor*>& file,
+                    std::set<string>* provided) const;
+  void FindProvidesForMessage(const GeneratorOptions& options,
+                              io::Printer* printer,
+                              const Descriptor* desc,
+                              std::set<string>* provided) const;
+  void FindProvidesForEnum(const GeneratorOptions& options,
+                           io::Printer* printer,
+                           const EnumDescriptor* enumdesc,
+                           std::set<string>* provided) const;
+  // For extension fields at file scope.
+  void FindProvidesForFields(const GeneratorOptions& options,
+                             io::Printer* printer,
+                             const vector<const FieldDescriptor*>& fields,
+                             std::set<string>* provided) const;
+  // Print the goog.provides() found by the methods above.
+  void GenerateProvides(const GeneratorOptions& options,
+                        io::Printer* printer,
+                        std::set<string>* provided) const;
+
+  // Generate goog.setTestOnly() if indicated.
+  void GenerateTestOnly(const GeneratorOptions& options,
+                        io::Printer* printer) const;
+
+  // Generate goog.requires() calls.
+  void GenerateRequires(const GeneratorOptions& options,
+                        io::Printer* printer,
+                        const vector<const FileDescriptor*>& file,
+                        std::set<string>* provided) const;
+  void GenerateRequires(const GeneratorOptions& options,
+                        io::Printer* printer,
+                        const Descriptor* desc,
+                        std::set<string>* provided) const;
+  // For extension fields at file scope.
+  void GenerateRequires(const GeneratorOptions& options,
+                        io::Printer* printer,
+                        const vector<const FieldDescriptor*>& fields,
+                        std::set<string>* provided) const;
+  void GenerateRequiresImpl(const GeneratorOptions& options,
+                            io::Printer* printer,
+                            std::set<string>* required,
+                            std::set<string>* forwards,
+                            std::set<string>* provided,
+                            bool require_jspb,
+                            bool require_extension) const;
+  void FindRequiresForMessage(const GeneratorOptions& options,
+                              const Descriptor* desc,
+                              std::set<string>* required,
+                              std::set<string>* forwards,
+                              bool* have_message) const;
+  void FindRequiresForField(const GeneratorOptions& options,
+                            const FieldDescriptor* field,
+                            std::set<string>* required,
+                            std::set<string>* forwards) const;
+  void FindRequiresForExtension(const GeneratorOptions& options,
+                                const FieldDescriptor* field,
+                                std::set<string>* required,
+                                std::set<string>* forwards) const;
+
+  // Generate definitions for all message classes and enums in all files,
+  // processing the files in dependence order.
+  void GenerateFilesInDepOrder(const GeneratorOptions& options,
+                               io::Printer* printer,
+                               const vector<const FileDescriptor*>& file) const;
+  // Helper for above.
+  void GenerateFileAndDeps(const GeneratorOptions& options,
+                           io::Printer* printer,
+                           const FileDescriptor* root,
+                           std::set<const FileDescriptor*>* all_files,
+                           std::set<const FileDescriptor*>* generated) const;
+
+  // Generate definitions for all message classes and enums.
+  void GenerateClassesAndEnums(const GeneratorOptions& options,
+                               io::Printer* printer,
+                               const FileDescriptor* file) const;
+
+  // Generate definition for one class.
+  void GenerateClass(const GeneratorOptions& options,
+                     io::Printer* printer,
+                     const Descriptor* desc) const;
+  void GenerateClassConstructor(const GeneratorOptions& options,
+                                io::Printer* printer,
+                                const Descriptor* desc) const;
+  void GenerateClassFieldInfo(const GeneratorOptions& options,
+                              io::Printer* printer,
+                              const Descriptor* desc) const;
+  void GenerateClassXid(const GeneratorOptions& options,
+                        io::Printer* printer,
+                        const Descriptor* desc) const;
+  void GenerateOneofCaseDefinition(const GeneratorOptions& options,
+                                   io::Printer* printer,
+                                   const OneofDescriptor* oneof) const;
+  void GenerateClassToObject(const GeneratorOptions& options,
+                             io::Printer* printer,
+                             const Descriptor* desc) const;
+  void GenerateClassFieldToObject(const GeneratorOptions& options,
+                                  io::Printer* printer,
+                                  const FieldDescriptor* field) const;
+  void GenerateClassFromObject(const GeneratorOptions& options,
+                               io::Printer* printer,
+                               const Descriptor* desc) const;
+  void GenerateClassFieldFromObject(const GeneratorOptions& options,
+                                    io::Printer* printer,
+                                    const FieldDescriptor* field) const;
+  void GenerateClassClone(const GeneratorOptions& options,
+                          io::Printer* printer,
+                          const Descriptor* desc) const;
+  void GenerateClassRegistration(const GeneratorOptions& options,
+                                 io::Printer* printer,
+                                 const Descriptor* desc) const;
+  void GenerateClassFields(const GeneratorOptions& options,
+                           io::Printer* printer,
+                           const Descriptor* desc) const;
+  void GenerateClassField(const GeneratorOptions& options,
+                          io::Printer* printer,
+                          const FieldDescriptor* desc) const;
+  void GenerateClassExtensionFieldInfo(const GeneratorOptions& options,
+                                       io::Printer* printer,
+                                       const Descriptor* desc) const;
+  void GenerateClassDeserialize(const GeneratorOptions& options,
+                                io::Printer* printer,
+                                const Descriptor* desc) const;
+  void GenerateClassDeserializeBinary(const GeneratorOptions& options,
+                                      io::Printer* printer,
+                                      const Descriptor* desc) const;
+  void GenerateClassDeserializeBinaryField(const GeneratorOptions& options,
+                                           io::Printer* printer,
+                                           const FieldDescriptor* field) const;
+  void GenerateClassSerializeBinary(const GeneratorOptions& options,
+                                    io::Printer* printer,
+                                    const Descriptor* desc) const;
+  void GenerateClassSerializeBinaryField(const GeneratorOptions& options,
+                                         io::Printer* printer,
+                                         const FieldDescriptor* field) const;
+
+  // Generate definition for one enum.
+  void GenerateEnum(const GeneratorOptions& options,
+                    io::Printer* printer,
+                    const EnumDescriptor* enumdesc) const;
+
+  // Generate an extension definition.
+  void GenerateExtension(const GeneratorOptions& options,
+                         io::Printer* printer,
+                         const FieldDescriptor* field) const;
+
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Generator);
+};
+
+}  // namespace js
+}  // namespace compiler
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_COMPILER_JS_GENERATOR_H__
diff --git a/src/google/protobuf/compiler/main.cc b/src/google/protobuf/compiler/main.cc
index 584e5a40..97df536e 100644
--- a/src/google/protobuf/compiler/main.cc
+++ b/src/google/protobuf/compiler/main.cc
@@ -38,6 +38,7 @@
 #include <google/protobuf/compiler/ruby/ruby_generator.h>
 #include <google/protobuf/compiler/csharp/csharp_generator.h>
 #include <google/protobuf/compiler/objectivec/objectivec_generator.h>
+#include <google/protobuf/compiler/js/js_generator.h>
 
 int main(int argc, char* argv[]) {
 
@@ -80,5 +81,10 @@ int main(int argc, char* argv[]) {
   cli.RegisterGenerator("--objc_out", &objc_generator,
                         "Generate Objective C header and source.");
 
+  // JavaScript
+  google::protobuf::compiler::js::Generator js_generator;
+  cli.RegisterGenerator("--js_out", &js_generator,
+                        "Generate JavaScript source.");
+
   return cli.Run(argc, argv);
 }
diff --git a/src/google/protobuf/compiler/mock_code_generator.cc b/src/google/protobuf/compiler/mock_code_generator.cc
index 98261431..121d917b 100644
--- a/src/google/protobuf/compiler/mock_code_generator.cc
+++ b/src/google/protobuf/compiler/mock_code_generator.cc
@@ -147,6 +147,12 @@ bool MockCodeGenerator::Generate(
         std::cerr << "Saw message type MockCodeGenerator_HasSourceCodeInfo: "
                   << has_source_code_info << "." << std::endl;
         abort();
+      } else if (command == "HasJsonName") {
+        FieldDescriptorProto field_descriptor_proto;
+        file->message_type(i)->field(0)->CopyTo(&field_descriptor_proto);
+        std::cerr << "Saw json_name: "
+                  << field_descriptor_proto.has_json_name() << std::endl;
+        abort();
       } else {
         GOOGLE_LOG(FATAL) << "Unknown MockCodeGenerator command: " << command;
       }
diff --git a/src/google/protobuf/compiler/parser.cc b/src/google/protobuf/compiler/parser.cc
index a389a4fc..ea792a9d 100644
--- a/src/google/protobuf/compiler/parser.cc
+++ b/src/google/protobuf/compiler/parser.cc
@@ -458,6 +458,61 @@ void Parser::SkipRestOfBlock() {
 
 // ===================================================================
 
+bool Parser::ValidateEnum(const EnumDescriptorProto* proto) {
+  bool has_allow_alias = false;
+  bool allow_alias = false;
+
+  for (int i = 0; i < proto->options().uninterpreted_option_size(); i++) {
+    const UninterpretedOption option = proto->options().uninterpreted_option(i);
+    if (option.name_size() > 1) {
+      continue;
+    }
+    if (!option.name(0).is_extension() &&
+        option.name(0).name_part() == "allow_alias") {
+      has_allow_alias = true;
+      if (option.identifier_value() == "true") {
+        allow_alias = true;
+      }
+      break;
+    }
+  }
+
+  if (has_allow_alias && !allow_alias) {
+    string error =
+        "\"" + proto->name() +
+        "\" declares 'option allow_alias = false;' which has no effect. "
+        "Please remove the declaration.";
+    // This needlessly clutters declarations with nops.
+    AddError(error);
+    return false;
+  }
+
+  set<int> used_values;
+  bool has_duplicates = false;
+  for (int i = 0; i < proto->value_size(); ++i) {
+    const EnumValueDescriptorProto enum_value = proto->value(i);
+    if (used_values.find(enum_value.number()) != used_values.end()) {
+      has_duplicates = true;
+      break;
+    } else {
+      used_values.insert(enum_value.number());
+    }
+  }
+  if (allow_alias && !has_duplicates) {
+    string error =
+        "\"" + proto->name() +
+        "\" declares support for enum aliases but no enum values share field "
+        "numbers. Please remove the unnecessary 'option allow_alias = true;' "
+        "declaration.";
+    // Generate an error if an enum declares support for duplicate enum values
+    // and does not use it protect future authors.
+    AddError(error);
+    return false;
+  }
+
+  return true;
+}
+
 bool Parser::Parse(io::Tokenizer* input, FileDescriptorProto* file) {
   input_ = input;
   had_errors_ = false;
@@ -1627,6 +1682,9 @@ bool Parser::ParseEnumDefinition(EnumDescriptorProto* enum_type,
   }
 
   DO(ParseEnumBlock(enum_type, enum_location, containing_file));
+
+  DO(ValidateEnum(enum_type));
+
   return true;
 }
 
diff --git a/src/google/protobuf/compiler/parser.h b/src/google/protobuf/compiler/parser.h
index 3ba1e170..2c561c23 100644
--- a/src/google/protobuf/compiler/parser.h
+++ b/src/google/protobuf/compiler/parser.h
@@ -498,6 +498,8 @@ class LIBPROTOBUF_EXPORT Parser {
   }
 
 
+  bool ValidateEnum(const EnumDescriptorProto* proto);
+
   // =================================================================
 
   io::Tokenizer* input_;
diff --git a/src/google/protobuf/compiler/parser_unittest.cc b/src/google/protobuf/compiler/parser_unittest.cc
index 0d729e0b..1d623dd9 100644
--- a/src/google/protobuf/compiler/parser_unittest.cc
+++ b/src/google/protobuf/compiler/parser_unittest.cc
@@ -1170,6 +1170,29 @@ TEST_F(ParseErrorTest, EnumValueOutOfRange) {
     "4:19: Integer out of range.\n");
 }
 
+TEST_F(ParseErrorTest, EnumAllowAliasFalse) {
+  ExpectHasErrors(
+    "enum Foo {\n"
+    "  option allow_alias = false;\n"
+    "  BAR = 1;\n"
+    "  BAZ = 2;\n"
+    "}\n",
+    "5:0: \"Foo\" declares 'option allow_alias = false;' which has no effect. "
+    "Please remove the declaration.\n");
+}
+
+TEST_F(ParseErrorTest, UnnecessaryEnumAllowAlias) {
+  ExpectHasErrors(
+    "enum Foo {\n"
+    "  option allow_alias = true;\n"
+    "  BAR = 1;\n"
+    "  BAZ = 2;\n"
+    "}\n",
+    "5:0: \"Foo\" declares support for enum aliases but no enum values share "
+    "field numbers. Please remove the unnecessary 'option allow_alias = true;' "
+    "declaration.\n");
+}
+
 TEST_F(ParseErrorTest, DefaultValueMissing) {
   ExpectHasErrors(
     "message TestMessage {\n"
@@ -1839,6 +1862,8 @@ TEST_F(ParseDescriptorDebugTest, TestCommentsInDebugString) {
       "// Detached comment before TestMessage1.\n"
       "\n"
       "// Message comment.\n"
+      "//\n"
+      "// More detail in message comment.\n"
       "message TestMessage1 {\n"
       "\n"
       "  // Detached comment before foo.\n"
@@ -1890,11 +1915,6 @@ TEST_F(ParseDescriptorDebugTest, TestCommentsInDebugString) {
       pool_.BuildFileCollectingErrors(parsed_desc, &collector);
   ASSERT_TRUE(descriptor != NULL);
 
-  DebugStringOptions debug_string_options;
-  debug_string_options.include_comments = true;
-  const string debug_string =
-      descriptor->DebugStringWithOptions(debug_string_options);
-
   // Ensure that each of the comments appears somewhere in the DebugString().
   // We don't test the exact comment placement or formatting, because we do not
   // want to be too fragile here.
@@ -1905,6 +1925,7 @@ TEST_F(ParseDescriptorDebugTest, TestCommentsInDebugString) {
     "Package comment.",
     "Detached comment before TestMessage1.",
     "Message comment.",
+    "More detail in message comment.",
     "Detached comment before foo.",
     "Field comment",
     "Detached comment before NestedMessage.",
@@ -1919,11 +1940,28 @@ TEST_F(ParseDescriptorDebugTest, TestCommentsInDebugString) {
     "RPC comment",
   };
 
-  for (int i = 0; i < GOOGLE_ARRAYSIZE(expected_comments); ++i) {
-    string::size_type found_pos = debug_string.find(expected_comments[i]);
-    EXPECT_TRUE(found_pos != string::npos)
-        << "\"" << expected_comments[i] << "\" not found.";
+  DebugStringOptions debug_string_options;
+  debug_string_options.include_comments = true;
+
+  {
+    const string debug_string =
+        descriptor->DebugStringWithOptions(debug_string_options);
+
+    for (int i = 0; i < GOOGLE_ARRAYSIZE(expected_comments); ++i) {
+      string::size_type found_pos = debug_string.find(expected_comments[i]);
+      EXPECT_TRUE(found_pos != string::npos)
+          << "\"" << expected_comments[i] << "\" not found.";
+    }
+
+    // Result of DebugStringWithOptions should be parseable.
+    SetupParser(debug_string.c_str());
+    FileDescriptorProto parsed;
+    parser_->Parse(input_.get(), &parsed);
+    EXPECT_EQ(io::Tokenizer::TYPE_END, input_->current().type);
+    ASSERT_EQ("", error_collector_.text_)
+        << "Failed to parse:\n" << debug_string;
   }
+
 }
 
 TEST_F(ParseDescriptorDebugTest, TestMaps) {
diff --git a/src/google/protobuf/compiler/plugin.pb.cc b/src/google/protobuf/compiler/plugin.pb.cc
index 636673ae..a2da8eee 100644
--- a/src/google/protobuf/compiler/plugin.pb.cc
+++ b/src/google/protobuf/compiler/plugin.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/compiler/subprocess.cc b/src/google/protobuf/compiler/subprocess.cc
index 85429924..a30ac305 100644
--- a/src/google/protobuf/compiler/subprocess.cc
+++ b/src/google/protobuf/compiler/subprocess.cc
@@ -47,6 +47,7 @@
 #include <google/protobuf/message.h>
 #include <google/protobuf/stubs/substitute.h>
 
+
 namespace google {
 namespace protobuf {
 namespace compiler {
diff --git a/src/google/protobuf/descriptor.cc b/src/google/protobuf/descriptor.cc
index 9a1c6fe8..1aac360b 100644
--- a/src/google/protobuf/descriptor.cc
+++ b/src/google/protobuf/descriptor.cc
@@ -2050,6 +2050,7 @@ class SourceLocationCommentPrinter {
   }
 
  private:
+
   bool have_source_loc_;
   SourceLocation source_loc_;
   DebugStringOptions options_;
@@ -2951,7 +2952,8 @@ class DescriptorBuilder {
                    const ServiceDescriptor* parent,
                    MethodDescriptor* result);
 
-  void LogUnusedDependency(const FileDescriptor* result);
+  void LogUnusedDependency(const FileDescriptorProto& proto,
+                           const FileDescriptor* result);
 
   // Must be run only after building.
   //
@@ -3996,7 +3998,7 @@ const FileDescriptor* DescriptorBuilder::BuildFile(
 
 
   if (!unused_dependency_.empty()) {
-    LogUnusedDependency(result);
+    LogUnusedDependency(proto, result);
   }
 
   if (had_errors_) {
@@ -4143,6 +4145,7 @@ void DescriptorBuilder::BuildMessage(const DescriptorProto& proto,
   }
 }
 
+
 void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
                                               const Descriptor* parent,
                                               FieldDescriptor* result,
@@ -4248,8 +4251,8 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
           } else if (proto.default_value() == "nan") {
             result->default_value_float_ = numeric_limits<float>::quiet_NaN();
           } else  {
-            result->default_value_float_ =
-              io::NoLocaleStrtod(proto.default_value().c_str(), &end_pos);
+            result->default_value_float_ = io::SafeDoubleToFloat(
+                io::NoLocaleStrtod(proto.default_value().c_str(), &end_pos));
           }
           break;
         case FieldDescriptor::CPPTYPE_DOUBLE:
@@ -4421,6 +4424,7 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
     AllocateOptions(proto.options(), result);
   }
 
+
   AddSymbol(result->full_name(), parent, result->name(),
             proto, Symbol(result));
 }
@@ -5533,11 +5537,19 @@ bool DescriptorBuilder::OptionInterpreter::InterpretOptions(
     // UnknownFieldSet and wait there until the message is parsed by something
     // that does know about the options.
     string buf;
-    options->AppendToString(&buf);
-    GOOGLE_CHECK(options->ParseFromString(buf))
+    GOOGLE_CHECK(options->AppendPartialToString(&buf))
+        << "Protocol message could not be serialized.";
+    GOOGLE_CHECK(options->ParsePartialFromString(buf))
         << "Protocol message serialized itself in invalid fashion.";
+    if (!options->IsInitialized()) {
+      builder_->AddWarning(
+          options_to_interpret->element_name, *original_options,
+          DescriptorPool::ErrorCollector::OTHER,
+          "Options could not be fully parsed using the proto descriptors "
+          "compiled into this binary. Missing required fields: " +
+          options->InitializationErrorString());
+    }
   }
-
   return !failed;
 }
 
@@ -6191,7 +6203,8 @@ void DescriptorBuilder::OptionInterpreter::SetUInt64(int number, uint64 value,
   }
 }
 
-void DescriptorBuilder::LogUnusedDependency(const FileDescriptor* result) {
+void DescriptorBuilder::LogUnusedDependency(const FileDescriptorProto& proto,
+                                            const FileDescriptor* result) {
 
   if (!unused_dependency_.empty()) {
     std::set<string> annotation_extensions;
@@ -6217,9 +6230,9 @@ void DescriptorBuilder::LogUnusedDependency(const FileDescriptor* result) {
       }
       // Log warnings for unused imported files.
       if (i == (*it)->extension_count()) {
-        GOOGLE_LOG(WARNING) << "Warning: Unused import: \"" << result->name()
-                     << "\" imports \"" << (*it)->name()
-                     << "\" which is not used.";
+        string error_message = "Import " + (*it)->name() + " but not used.";
+        AddWarning((*it)->name(), proto, DescriptorPool::ErrorCollector::OTHER,
+                   error_message);
       }
     }
   }
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index bc846609..eda6280f 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/descriptor_unittest.cc b/src/google/protobuf/descriptor_unittest.cc
index ccd0650d..be8e0b72 100644
--- a/src/google/protobuf/descriptor_unittest.cc
+++ b/src/google/protobuf/descriptor_unittest.cc
@@ -178,6 +178,61 @@ void AddEmptyEnum(FileDescriptorProto* file, const string& name) {
   AddEnumValue(AddEnum(file, name), name + "_DUMMY", 1);
 }
 
+class MockErrorCollector : public DescriptorPool::ErrorCollector {
+ public:
+  MockErrorCollector() {}
+  ~MockErrorCollector() {}
+
+  string text_;
+  string warning_text_;
+
+  // implements ErrorCollector ---------------------------------------
+  void AddError(const string& filename,
+                const string& element_name, const Message* descriptor,
+                ErrorLocation location, const string& message) {
+    const char* location_name = NULL;
+    switch (location) {
+      case NAME         : location_name = "NAME"         ; break;
+      case NUMBER       : location_name = "NUMBER"       ; break;
+      case TYPE         : location_name = "TYPE"         ; break;
+      case EXTENDEE     : location_name = "EXTENDEE"     ; break;
+      case DEFAULT_VALUE: location_name = "DEFAULT_VALUE"; break;
+      case OPTION_NAME  : location_name = "OPTION_NAME"  ; break;
+      case OPTION_VALUE : location_name = "OPTION_VALUE" ; break;
+      case INPUT_TYPE   : location_name = "INPUT_TYPE"   ; break;
+      case OUTPUT_TYPE  : location_name = "OUTPUT_TYPE"  ; break;
+      case OTHER        : location_name = "OTHER"        ; break;
+    }
+
+    strings::SubstituteAndAppend(
+      &text_, "$0: $1: $2: $3\n",
+      filename, element_name, location_name, message);
+  }
+
+  // implements ErrorCollector ---------------------------------------
+  void AddWarning(const string& filename, const string& element_name,
+                  const Message* descriptor, ErrorLocation location,
+                  const string& message) {
+    const char* location_name = NULL;
+    switch (location) {
+      case NAME         : location_name = "NAME"         ; break;
+      case NUMBER       : location_name = "NUMBER"       ; break;
+      case TYPE         : location_name = "TYPE"         ; break;
+      case EXTENDEE     : location_name = "EXTENDEE"     ; break;
+      case DEFAULT_VALUE: location_name = "DEFAULT_VALUE"; break;
+      case OPTION_NAME  : location_name = "OPTION_NAME"  ; break;
+      case OPTION_VALUE : location_name = "OPTION_VALUE" ; break;
+      case INPUT_TYPE   : location_name = "INPUT_TYPE"   ; break;
+      case OUTPUT_TYPE  : location_name = "OUTPUT_TYPE"  ; break;
+      case OTHER        : location_name = "OTHER"        ; break;
+    }
+
+    strings::SubstituteAndAppend(
+      &warning_text_, "$0: $1: $2: $3\n",
+      filename, element_name, location_name, message);
+  }
+};
+
 // ===================================================================
 
 // Test simple files.
@@ -3120,77 +3175,95 @@ TEST(CustomOptions, UnusedImportWarning) {
       ->file()->CopyTo(&file_proto);
   ASSERT_TRUE(pool.BuildFile(file_proto) != NULL);
 
-
   pool.AddUnusedImportTrackFile("custom_options_import.proto");
   ASSERT_TRUE(TextFormat::ParseFromString(
     "name: \"custom_options_import.proto\" "
     "package: \"protobuf_unittest\" "
     "dependency: \"google/protobuf/unittest_custom_options.proto\" ",
     &file_proto));
-  pool.BuildFile(file_proto);
-}
 
-// ===================================================================
+  MockErrorCollector error_collector;
+  EXPECT_TRUE(pool.BuildFileCollectingErrors(file_proto, &error_collector));
+  EXPECT_EQ("", error_collector.warning_text_);
+}
 
-// The tests below trigger every unique call to AddError() in descriptor.cc,
-// in the order in which they appear in that file.  I'm using TextFormat here
-// to specify the input descriptors because building them using code would
-// be too bulky.
+// Verifies that proto files can correctly be parsed, even if the
+// custom options defined in the file are incompatible with those
+// compiled in the binary. See http://b/19276250.
+TEST(CustomOptions, OptionsWithRequiredEnums) {
+  DescriptorPool pool;
 
-class MockErrorCollector : public DescriptorPool::ErrorCollector {
- public:
-  MockErrorCollector() {}
-  ~MockErrorCollector() {}
+  FileDescriptorProto file_proto;
+  MessageOptions::descriptor()->file()->CopyTo(&file_proto);
+  ASSERT_TRUE(pool.BuildFile(file_proto) != NULL);
 
-  string text_;
-  string warning_text_;
+  // Create a new file descriptor proto containing a subset of the
+  // messages defined in google/protobuf/unittest_custom_options.proto.
+  file_proto.Clear();
+  file_proto.set_name("unittest_custom_options.proto");
+  file_proto.set_package("protobuf_unittest");
+  file_proto.add_dependency("google/protobuf/descriptor.proto");
 
-  // implements ErrorCollector ---------------------------------------
-  void AddError(const string& filename,
-                const string& element_name, const Message* descriptor,
-                ErrorLocation location, const string& message) {
-    const char* location_name = NULL;
-    switch (location) {
-      case NAME         : location_name = "NAME"         ; break;
-      case NUMBER       : location_name = "NUMBER"       ; break;
-      case TYPE         : location_name = "TYPE"         ; break;
-      case EXTENDEE     : location_name = "EXTENDEE"     ; break;
-      case DEFAULT_VALUE: location_name = "DEFAULT_VALUE"; break;
-      case OPTION_NAME  : location_name = "OPTION_NAME"  ; break;
-      case OPTION_VALUE : location_name = "OPTION_VALUE" ; break;
-      case INPUT_TYPE   : location_name = "INPUT_TYPE"   ; break;
-      case OUTPUT_TYPE  : location_name = "OUTPUT_TYPE"  ; break;
-      case OTHER        : location_name = "OTHER"        ; break;
-    }
+  // Add the "required_enum_opt" extension.
+  FieldDescriptorProto* extension = file_proto.add_extension();
+  protobuf_unittest::OldOptionType::descriptor()->file()
+      ->FindExtensionByName("required_enum_opt")->CopyTo(extension);
+
+  // Add a test message that uses the "required_enum_opt" option.
+  DescriptorProto* test_message_type = file_proto.add_message_type();
+  protobuf_unittest::TestMessageWithRequiredEnumOption::descriptor()
+      ->CopyTo(test_message_type);
+
+  // Instruct the extension to use NewOptionType instead of
+  // OldOptionType, and add the descriptor of NewOptionType.
+  extension->set_type_name(".protobuf_unittest.NewOptionType");
+  DescriptorProto* new_option_type = file_proto.add_message_type();
+  protobuf_unittest::NewOptionType::descriptor()
+      ->CopyTo(new_option_type);
+
+  // Replace the value of the "required_enum_opt" option used in the
+  // test message with an enum value that only exists in NewOptionType.
+  ASSERT_TRUE(TextFormat::ParseFromString(
+      "uninterpreted_option { "
+      "  name { "
+      "    name_part: 'required_enum_opt' "
+      "    is_extension: true "
+      "  } "
+      "  aggregate_value: 'value: NEW_VALUE' "
+      "}",
+      test_message_type->mutable_options()));
 
-    strings::SubstituteAndAppend(
-      &text_, "$0: $1: $2: $3\n",
-      filename, element_name, location_name, message);
-  }
+  // Add the file descriptor to the pool.
+  ASSERT_TRUE(pool.BuildFile(file_proto) != NULL);
 
-  // implements ErrorCollector ---------------------------------------
-  void AddWarning(const string& filename, const string& element_name,
-                  const Message* descriptor, ErrorLocation location,
-                  const string& message) {
-    const char* location_name = NULL;
-    switch (location) {
-      case NAME         : location_name = "NAME"         ; break;
-      case NUMBER       : location_name = "NUMBER"       ; break;
-      case TYPE         : location_name = "TYPE"         ; break;
-      case EXTENDEE     : location_name = "EXTENDEE"     ; break;
-      case DEFAULT_VALUE: location_name = "DEFAULT_VALUE"; break;
-      case OPTION_NAME  : location_name = "OPTION_NAME"  ; break;
-      case OPTION_VALUE : location_name = "OPTION_VALUE" ; break;
-      case INPUT_TYPE   : location_name = "INPUT_TYPE"   ; break;
-      case OUTPUT_TYPE  : location_name = "OUTPUT_TYPE"  ; break;
-      case OTHER        : location_name = "OTHER"        ; break;
-    }
+  // Find the test message.
+  const Descriptor* test_message = pool.FindMessageTypeByName(
+      "protobuf_unittest.TestMessageWithRequiredEnumOption");
+  ASSERT_TRUE(test_message != NULL);
+
+  const MessageOptions& options = test_message->options();
+  // Extract the "required_enum_opt" option. Since the binary does not
+  // know that the extension was updated, this will still return an
+  // OldOptionType message.
+  ASSERT_TRUE(
+      options.HasExtension(protobuf_unittest::required_enum_opt));
+  const protobuf_unittest::OldOptionType& old_enum_opt =
+      options.GetExtension(protobuf_unittest::required_enum_opt);
+
+  // Confirm that the required enum field is missing.
+  EXPECT_FALSE(old_enum_opt.IsInitialized());
+  EXPECT_FALSE(old_enum_opt.has_value());
+
+  string buf;
+  // Verify that the required enum field does show up when the option
+  // is re-parsed as a NewOptionType message;
+  protobuf_unittest::NewOptionType new_enum_opt;
+  EXPECT_TRUE(old_enum_opt.AppendPartialToString(&buf));
+  EXPECT_TRUE(new_enum_opt.ParseFromString(buf));
+  EXPECT_EQ(protobuf_unittest::NewOptionType::NEW_VALUE, new_enum_opt.value());
+}
 
-    strings::SubstituteAndAppend(
-      &warning_text_, "$0: $1: $2: $3\n",
-      filename, element_name, location_name, message);
-  }
-};
+// ===================================================================
 
 class ValidationErrorTest : public testing::Test {
  protected:
@@ -5123,7 +5196,6 @@ TEST_F(ValidationErrorTest, AllowEnumAlias) {
 }
 
 TEST_F(ValidationErrorTest, UnusedImportWarning) {
-
   pool_.AddUnusedImportTrackFile("bar.proto");
   BuildFile(
     "name: \"bar.proto\" "
@@ -5155,7 +5227,7 @@ TEST_F(ValidationErrorTest, UnusedImportWarning) {
   // }
   //
   pool_.AddUnusedImportTrackFile("forward.proto");
-  BuildFile(
+  BuildFileWithWarnings(
     "name: \"forward.proto\""
     "dependency: \"base.proto\""
     "dependency: \"bar.proto\""
@@ -5165,7 +5237,8 @@ TEST_F(ValidationErrorTest, UnusedImportWarning) {
     "message_type {"
     "  name: \"Forward\""
     "  field { name:\"base\" number:1 label:LABEL_OPTIONAL type_name:\"Base\" }"
-    "}");
+    "}",
+    "forward.proto: bar.proto: OTHER: Import bar.proto but not used.\n");
 }
 
 namespace {
diff --git a/src/google/protobuf/duration.pb.cc b/src/google/protobuf/duration.pb.cc
index c7eed0d5..b325944e 100644
--- a/src/google/protobuf/duration.pb.cc
+++ b/src/google/protobuf/duration.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/duration.proto b/src/google/protobuf/duration.proto
index 7f172aa6..78bcc74b 100644
--- a/src/google/protobuf/duration.proto
+++ b/src/google/protobuf/duration.proto
@@ -27,15 +27,16 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "DurationProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option java_package = "com.google.protobuf";
+option java_outer_classname = "DurationProto";
+option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
 // A Duration represents a signed, fixed-length span of time represented
diff --git a/src/google/protobuf/dynamic_message.cc b/src/google/protobuf/dynamic_message.cc
index 091fc975..bb400476 100644
--- a/src/google/protobuf/dynamic_message.cc
+++ b/src/google/protobuf/dynamic_message.cc
@@ -69,8 +69,8 @@
 #include <google/protobuf/stubs/shared_ptr.h>
 #endif
 
-#include <google/protobuf/stubs/scoped_ptr.h>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/scoped_ptr.h>
 
 #include <google/protobuf/dynamic_message.h>
 #include <google/protobuf/descriptor.h>
diff --git a/src/google/protobuf/empty.pb.cc b/src/google/protobuf/empty.pb.cc
index 4a4f6eae..f2eec782 100644
--- a/src/google/protobuf/empty.pb.cc
+++ b/src/google/protobuf/empty.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
@@ -79,9 +80,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fempty_2eproto() {
 
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\033google/protobuf/empty.proto\022\017google.pr"
-    "otobuf\"\007\n\005EmptyBM\n\023com.google.protobufB\n"
-    "EmptyProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Protobuf."
-    "WellKnownTypesb\006proto3", 142);
+    "otobuf\"\007\n\005EmptyBP\n\023com.google.protobufB\n"
+    "EmptyProtoP\001\240\001\001\370\001\001\242\002\003GPB\252\002\036Google.Protob"
+    "uf.WellKnownTypesb\006proto3", 145);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/empty.proto", &protobuf_RegisterTypes);
   Empty::default_instance_ = new Empty();
@@ -117,6 +118,14 @@ Empty::Empty()
   // @@protoc_insertion_point(constructor:google.protobuf.Empty)
 }
 
+Empty::Empty(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.Empty)
+}
+
 void Empty::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -140,10 +149,20 @@ Empty::~Empty() {
 }
 
 void Empty::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void Empty::ArenaDtor(void* object) {
+  Empty* _this = reinterpret_cast< Empty* >(object);
+  (void)_this;
+}
+void Empty::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void Empty::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -162,11 +181,7 @@ const Empty& Empty::default_instance() {
 Empty* Empty::default_instance_ = NULL;
 
 Empty* Empty::New(::google::protobuf::Arena* arena) const {
-  Empty* n = new Empty;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<Empty>(arena);
 }
 
 void Empty::Clear() {
@@ -255,6 +270,18 @@ bool Empty::IsInitialized() const {
 
 void Empty::Swap(Empty* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    Empty temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void Empty::UnsafeArenaSwap(Empty* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void Empty::InternalSwap(Empty* other) {
diff --git a/src/google/protobuf/empty.pb.h b/src/google/protobuf/empty.pb.h
index 20876bea..868009fc 100644
--- a/src/google/protobuf/empty.pb.h
+++ b/src/google/protobuf/empty.pb.h
@@ -53,9 +53,14 @@ class LIBPROTOBUF_EXPORT Empty : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const Empty& default_instance();
 
+  void UnsafeArenaSwap(Empty* other);
   void Swap(Empty* other);
 
   // implements Message ----------------------------------------------
@@ -82,6 +87,11 @@ class LIBPROTOBUF_EXPORT Empty : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(Empty* other);
+  protected:
+  explicit Empty(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -101,6 +111,9 @@ class LIBPROTOBUF_EXPORT Empty : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   mutable int _cached_size_;
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fempty_2eproto();
diff --git a/src/google/protobuf/empty.proto b/src/google/protobuf/empty.proto
index 9dddc6c5..b96daf28 100644
--- a/src/google/protobuf/empty.proto
+++ b/src/google/protobuf/empty.proto
@@ -27,16 +27,18 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_multiple_files = true;
-option java_outer_classname = "EmptyProto";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option java_package = "com.google.protobuf";
+option java_outer_classname = "EmptyProto";
+option java_multiple_files = true;
 option java_generate_equals_and_hash = true;
-option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
+option cc_enable_arenas = true;
 
 // A generic empty message that you can re-use to avoid defining duplicated
 // empty messages in your APIs. A typical example is to use it as the request
diff --git a/src/google/protobuf/field_mask.pb.cc b/src/google/protobuf/field_mask.pb.cc
index f834363b..01a6ce56 100644
--- a/src/google/protobuf/field_mask.pb.cc
+++ b/src/google/protobuf/field_mask.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/field_mask.proto b/src/google/protobuf/field_mask.proto
index 8b21c692..908c8a86 100644
--- a/src/google/protobuf/field_mask.proto
+++ b/src/google/protobuf/field_mask.proto
@@ -27,16 +27,17 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "FieldMaskProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option java_package = "com.google.protobuf";
+option java_outer_classname = "FieldMaskProto";
+option java_multiple_files = true;
 option objc_class_prefix = "GPB";
+option java_generate_equals_and_hash = true;
 
 // `FieldMask` represents a set of symbolic field paths, for example:
 //
@@ -69,7 +70,7 @@ option objc_class_prefix = "GPB";
 //     z: 8
 //
 // The result will not contain specific values for fields x,y and z
-// (there value will be set to the default, and omitted in proto text
+// (their value will be set to the default, and omitted in proto text
 // output):
 //
 //
diff --git a/src/google/protobuf/io/coded_stream.h b/src/google/protobuf/io/coded_stream.h
index cb1869a7..2da096c5 100644
--- a/src/google/protobuf/io/coded_stream.h
+++ b/src/google/protobuf/io/coded_stream.h
@@ -109,6 +109,7 @@
 #ifndef GOOGLE_PROTOBUF_IO_CODED_STREAM_H__
 #define GOOGLE_PROTOBUF_IO_CODED_STREAM_H__
 
+#include <assert.h>
 #include <string>
 #include <utility>
 #ifdef _MSC_VER
diff --git a/src/google/protobuf/io/strtod.cc b/src/google/protobuf/io/strtod.cc
index 579de9aa..a90bb9a3 100644
--- a/src/google/protobuf/io/strtod.cc
+++ b/src/google/protobuf/io/strtod.cc
@@ -32,6 +32,7 @@
 
 #include <cstdio>
 #include <cstring>
+#include <limits>
 #include <string>
 
 #include <google/protobuf/stubs/logging.h>
@@ -109,6 +110,16 @@ double NoLocaleStrtod(const char* text, char** original_endptr) {
   return result;
 }
 
+float SafeDoubleToFloat(double value) {
+  if (value > std::numeric_limits<float>::max()) {
+    return std::numeric_limits<float>::infinity();
+  } else if (value < -std::numeric_limits<float>::max()) {
+    return -std::numeric_limits<float>::infinity();
+  } else {
+    return static_cast<float>(value);
+  }
+}
+
 }  // namespace io
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/io/strtod.h b/src/google/protobuf/io/strtod.h
index c2efc8d3..f56e41c8 100644
--- a/src/google/protobuf/io/strtod.h
+++ b/src/google/protobuf/io/strtod.h
@@ -43,6 +43,11 @@ namespace io {
 // uses a dot as the decimal separator.
 double NoLocaleStrtod(const char* str, char** endptr);
 
+// Casts a double value to a float value. If the value is outside of the
+// representable range of float, it will be converted to positive or negative
+// infinity.
+float SafeDoubleToFloat(double value);
+
 }  // namespace io
 }  // namespace protobuf
 
diff --git a/src/google/protobuf/io/tokenizer.cc b/src/google/protobuf/io/tokenizer.cc
index 7ccd633d..3d57707c 100644
--- a/src/google/protobuf/io/tokenizer.cc
+++ b/src/google/protobuf/io/tokenizer.cc
@@ -375,7 +375,7 @@ void Tokenizer::ConsumeString(char delimiter) {
           // Possibly followed by two more octal digits, but these will
           // just be consumed by the main loop anyway so we don't need
           // to do so explicitly here.
-        } else if (TryConsume('x') || TryConsume('X')) {
+        } else if (TryConsume('x')) {
           if (!TryConsumeOne<HexDigit>()) {
             AddError("Expected hex digits for escape sequence.");
           }
diff --git a/src/google/protobuf/io/tokenizer_unittest.cc b/src/google/protobuf/io/tokenizer_unittest.cc
index 6526056a..20d50a2c 100644
--- a/src/google/protobuf/io/tokenizer_unittest.cc
+++ b/src/google/protobuf/io/tokenizer_unittest.cc
@@ -875,6 +875,8 @@ ErrorCase kErrorCases[] = {
   // String errors.
   { "'\\l' foo", true,
     "0:2: Invalid escape sequence in string literal.\n" },
+  { "'\\X' foo", true,
+    "0:2: Invalid escape sequence in string literal.\n" },
   { "'\\x' foo", true,
     "0:3: Expected hex digits for escape sequence.\n" },
   { "'foo", false,
diff --git a/src/google/protobuf/map.h b/src/google/protobuf/map.h
index 4bd76f25..dfc62420 100644
--- a/src/google/protobuf/map.h
+++ b/src/google/protobuf/map.h
@@ -188,7 +188,6 @@ class LIBPROTOBUF_EXPORT MapKey {
       case FieldDescriptor::CPPTYPE_ENUM:
       case FieldDescriptor::CPPTYPE_MESSAGE:
         GOOGLE_LOG(FATAL) << "Can't get here.";
-        return false;
     }
     GOOGLE_LOG(FATAL) << "Can't get here.";
     return false;
@@ -497,7 +496,7 @@ class Map {
     insert(other.begin(), other.end());
   }
   template <class InputIt>
-  explicit Map(const InputIt& first, const InputIt& last)
+  Map(const InputIt& first, const InputIt& last)
       : arena_(NULL),
         allocator_(arena_),
         elements_(0, hasher(), key_equal(), allocator_),
@@ -546,9 +545,7 @@ class Map {
     }
 
 #if __cplusplus >= 201103L && !defined(GOOGLE_PROTOBUF_OS_APPLE) && \
-    !defined(GOOGLE_PROTOBUF_OS_NACL) &&                            \
-    !defined(GOOGLE_PROTOBUF_OS_ANDROID) &&                         \
-    !defined(GOOGLE_PROTOBUF_OS_EMSCRIPTEN)
+    !defined(GOOGLE_PROTOBUF_OS_NACL) && !defined(GOOGLE_PROTOBUF_OS_ANDROID)
     template<class NodeType, class... Args>
     void construct(NodeType* p, Args&&... args) {
       new (static_cast<void*>(p)) NodeType(std::forward<Args>(args)...);
@@ -586,21 +583,22 @@ class Map {
 
    private:
     typedef void DestructorSkippable_;
-    Arena* arena_;
+    Arena* const arena_;
 
     template <typename X>
     friend class MapAllocator;
   };
 
- public:
   typedef MapAllocator<std::pair<const Key, MapPair<Key, T>*> > Allocator;
+  typedef hash_map<Key, value_type*, hash<Key>, equal_to<Key>, Allocator>
+      InnerMap;
 
+ public:
   // Iterators
   class const_iterator
       : public std::iterator<std::forward_iterator_tag, value_type, ptrdiff_t,
                              const value_type*, const value_type&> {
-    typedef typename hash_map<Key, value_type*, hash<Key>, equal_to<Key>,
-                              Allocator>::const_iterator InnerIt;
+    typedef typename InnerMap::const_iterator InnerIt;
 
    public:
     const_iterator() {}
@@ -627,8 +625,7 @@ class Map {
   };
 
   class iterator : public std::iterator<std::forward_iterator_tag, value_type> {
-    typedef typename hash_map<Key, value_type*, hasher, equal_to<Key>,
-                              Allocator>::iterator InnerIt;
+    typedef typename InnerMap::iterator InnerIt;
 
    public:
     iterator() {}
@@ -744,8 +741,7 @@ class Map {
 
   // Erase
   size_type erase(const key_type& key) {
-    typename hash_map<Key, value_type*, hash<Key>, equal_to<Key>,
-                      Allocator>::iterator it = elements_.find(key);
+    typename InnerMap::iterator it = elements_.find(key);
     if (it == elements_.end()) {
       return 0;
     } else {
@@ -815,7 +811,7 @@ class Map {
 
   Arena* arena_;
   Allocator allocator_;
-  hash_map<Key, value_type*, hash<Key>, equal_to<Key>, Allocator> elements_;
+  InnerMap elements_;
   int default_enum_value_;
 
   friend class ::google::protobuf::Arena;
@@ -854,7 +850,6 @@ struct hash<google::protobuf::MapKey> {
       case google::protobuf::FieldDescriptor::CPPTYPE_ENUM:
       case google::protobuf::FieldDescriptor::CPPTYPE_MESSAGE:
         GOOGLE_LOG(FATAL) << "Can't get here.";
-        return 0;
     }
     GOOGLE_LOG(FATAL) << "Can't get here.";
     return 0;
@@ -879,7 +874,6 @@ struct hash<google::protobuf::MapKey> {
       case google::protobuf::FieldDescriptor::CPPTYPE_ENUM:
       case google::protobuf::FieldDescriptor::CPPTYPE_MESSAGE:
         GOOGLE_LOG(FATAL) << "Can't get here.";
-        return true;
     }
     GOOGLE_LOG(FATAL) << "Can't get here.";
     return true;
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h
index 5530fefe..432236ce 100644
--- a/src/google/protobuf/repeated_field.h
+++ b/src/google/protobuf/repeated_field.h
@@ -208,10 +208,19 @@ class RepeatedField {
   // sizeof(*this)
   int SpaceUsedExcludingSelf() const;
 
-  // Remove the element referenced by position.
+  // Removes the element referenced by position.
+  //
+  // Returns an iterator to the element immediately following the removed
+  // element.
+  //
+  // Invalidates all iterators at or after the removed element, including end().
   iterator erase(const_iterator position);
 
-  // Remove the elements in the range [first, last).
+  // Removes the elements in the range [first, last).
+  //
+  // Returns an iterator to the element immediately following the removed range.
+  //
+  // Invalidates all iterators at or after the removed range, including end().
   iterator erase(const_iterator first, const_iterator last);
 
   // Get the Arena on which this RepeatedField stores its elements.
@@ -885,10 +894,19 @@ class RepeatedPtrField : public internal::RepeatedPtrFieldBase {
   // so will trigger a GOOGLE_DCHECK-failure.
   Element* ReleaseCleared();
 
-  // Remove the element referenced by position.
+  // Removes the element referenced by position.
+  //
+  // Returns an iterator to the element immediately following the removed
+  // element.
+  //
+  // Invalidates all iterators at or after the removed element, including end().
   iterator erase(const_iterator position);
 
   // Removes the elements in the range [first, last).
+  //
+  // Returns an iterator to the element immediately following the removed range.
+  //
+  // Invalidates all iterators at or after the removed range, including end().
   iterator erase(const_iterator first, const_iterator last);
 
   // Gets the arena on which this RepeatedPtrField stores its elements.
diff --git a/src/google/protobuf/source_context.pb.cc b/src/google/protobuf/source_context.pb.cc
index 1be3297e..f2eb7ae7 100644
--- a/src/google/protobuf/source_context.pb.cc
+++ b/src/google/protobuf/source_context.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/source_context.proto b/src/google/protobuf/source_context.proto
index e9a27d65..d76252ca 100644
--- a/src/google/protobuf/source_context.proto
+++ b/src/google/protobuf/source_context.proto
@@ -27,15 +27,16 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_multiple_files = true;
-option java_outer_classname = "SourceContextProto";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option java_package = "com.google.protobuf";
+option java_outer_classname = "SourceContextProto";
+option java_multiple_files = true;
 option java_generate_equals_and_hash = true;
-option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 // `SourceContext` represents information about the source of a
diff --git a/src/google/protobuf/struct.pb.cc b/src/google/protobuf/struct.pb.cc
index 273645d9..e020597a 100644
--- a/src/google/protobuf/struct.pb.cc
+++ b/src/google/protobuf/struct.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
diff --git a/src/google/protobuf/struct.proto b/src/google/protobuf/struct.proto
index b3e9e699..8562e2c1 100644
--- a/src/google/protobuf/struct.proto
+++ b/src/google/protobuf/struct.proto
@@ -27,15 +27,16 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "StructProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option java_package = "com.google.protobuf";
+option java_outer_classname = "StructProto";
+option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/stubs/strutil.cc b/src/google/protobuf/stubs/strutil.cc
index 8442f2ce..7ba92e8f 100644
--- a/src/google/protobuf/stubs/strutil.cc
+++ b/src/google/protobuf/stubs/strutil.cc
@@ -524,27 +524,81 @@ int CEscapeInternal(const char* src, int src_len, char* dest,
   return used;
 }
 
-int CEscapeString(const char* src, int src_len, char* dest, int dest_len) {
-  return CEscapeInternal(src, src_len, dest, dest_len, false, false);
+// Calculates the length of the C-style escaped version of 'src'.
+// Assumes that non-printable characters are escaped using octal sequences, and
+// that UTF-8 bytes are not handled specially.
+static inline size_t CEscapedLength(StringPiece src) {
+  static char c_escaped_len[256] = {
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 4, 4, 2, 4, 4,  // \t, \n, \r
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1,  // ", '
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // '0'..'9'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 'A'..'O'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1,  // 'P'..'Z', '\'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 'a'..'o'
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4,  // 'p'..'z', DEL
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+    4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+  };
+
+  size_t escaped_len = 0;
+  for (int i = 0; i < src.size(); ++i) {
+    unsigned char c = static_cast<unsigned char>(src[i]);
+    escaped_len += c_escaped_len[c];
+  }
+  return escaped_len;
 }
 
 // ----------------------------------------------------------------------
-// CEscape()
-// CHexEscape()
-//    Copies 'src' to result, escaping dangerous characters using
-//    C-style escape sequences. This is very useful for preparing query
-//    flags. 'src' and 'dest' should not overlap. The 'Hex' version
-//    hexadecimal rather than octal sequences.
-//
-//    Currently only \n, \r, \t, ", ', \ and !isprint() chars are escaped.
+// Escapes 'src' using C-style escape sequences, and appends the escaped string
+// to 'dest'. This version is faster than calling CEscapeInternal as it computes
+// the required space using a lookup table, and also does not do any special
+// handling for Hex or UTF-8 characters.
 // ----------------------------------------------------------------------
+void CEscapeAndAppend(StringPiece src, string* dest) {
+  size_t escaped_len = CEscapedLength(src);
+  if (escaped_len == src.size()) {
+    dest->append(src.data(), src.size());
+    return;
+  }
+
+  size_t cur_dest_len = dest->size();
+  dest->resize(cur_dest_len + escaped_len);
+  char* append_ptr = &(*dest)[cur_dest_len];
+
+  for (int i = 0; i < src.size(); ++i) {
+    unsigned char c = static_cast<unsigned char>(src[i]);
+    switch (c) {
+      case '\n': *append_ptr++ = '\\'; *append_ptr++ = 'n'; break;
+      case '\r': *append_ptr++ = '\\'; *append_ptr++ = 'r'; break;
+      case '\t': *append_ptr++ = '\\'; *append_ptr++ = 't'; break;
+      case '\"': *append_ptr++ = '\\'; *append_ptr++ = '\"'; break;
+      case '\'': *append_ptr++ = '\\'; *append_ptr++ = '\''; break;
+      case '\\': *append_ptr++ = '\\'; *append_ptr++ = '\\'; break;
+      default:
+        if (!isprint(c)) {
+          *append_ptr++ = '\\';
+          *append_ptr++ = '0' + c / 64;
+          *append_ptr++ = '0' + (c % 64) / 8;
+          *append_ptr++ = '0' + c % 8;
+        } else {
+          *append_ptr++ = c;
+        }
+        break;
+    }
+  }
+}
+
 string CEscape(const string& src) {
-  const int dest_length = src.size() * 4 + 1; // Maximum possible expansion
-  scoped_array<char> dest(new char[dest_length]);
-  const int len = CEscapeInternal(src.data(), src.size(),
-                                  dest.get(), dest_length, false, false);
-  GOOGLE_DCHECK_GE(len, 0);
-  return string(dest.get(), len);
+  string dest;
+  CEscapeAndAppend(src, &dest);
+  return dest;
 }
 
 namespace strings {
diff --git a/src/google/protobuf/stubs/strutil.h b/src/google/protobuf/stubs/strutil.h
index b22066b6..27d47575 100644
--- a/src/google/protobuf/stubs/strutil.h
+++ b/src/google/protobuf/stubs/strutil.h
@@ -314,26 +314,20 @@ LIBPROTOBUF_EXPORT int UnescapeCEscapeString(const string& src, string* dest,
 LIBPROTOBUF_EXPORT string UnescapeCEscapeString(const string& src);
 
 // ----------------------------------------------------------------------
-// CEscapeString()
-//    Copies 'src' to 'dest', escaping dangerous characters using
-//    C-style escape sequences. This is very useful for preparing query
-//    flags. 'src' and 'dest' should not overlap.
-//    Returns the number of bytes written to 'dest' (not including the \0)
-//    or -1 if there was insufficient space.
+// CEscape()
+//    Escapes 'src' using C-style escape sequences and returns the resulting
+//    string.
 //
-//    Currently only \n, \r, \t, ", ', \ and !isprint() chars are escaped.
+//    Escaped chars: \n, \r, \t, ", ', \, and !isprint().
 // ----------------------------------------------------------------------
-LIBPROTOBUF_EXPORT int CEscapeString(const char* src, int src_len,
-                                     char* dest, int dest_len);
+LIBPROTOBUF_EXPORT string CEscape(const string& src);
 
 // ----------------------------------------------------------------------
-// CEscape()
-//    More convenient form of CEscapeString: returns result as a "string".
-//    This version is slower than CEscapeString() because it does more
-//    allocation.  However, it is much more convenient to use in
-//    non-speed-critical code like logging messages etc.
+// CEscapeAndAppend()
+//    Escapes 'src' using C-style escape sequences, and appends the escaped
+//    string to 'dest'.
 // ----------------------------------------------------------------------
-LIBPROTOBUF_EXPORT string CEscape(const string& src);
+LIBPROTOBUF_EXPORT void CEscapeAndAppend(StringPiece src, string* dest);
 
 namespace strings {
 // Like CEscape() but does not escape bytes with the upper bit set.
diff --git a/src/google/protobuf/text_format.cc b/src/google/protobuf/text_format.cc
index 38b9069b..b0a5ce63 100644
--- a/src/google/protobuf/text_format.cc
+++ b/src/google/protobuf/text_format.cc
@@ -46,6 +46,7 @@
 #include <google/protobuf/dynamic_message.h>
 #include <google/protobuf/repeated_field.h>
 #include <google/protobuf/wire_format_lite.h>
+#include <google/protobuf/io/strtod.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/io/zero_copy_stream_impl.h>
@@ -380,6 +381,7 @@ class TextFormat::Parser::ParserImpl {
       string full_type_name, prefix;
       DO(ConsumeAnyTypeUrl(&full_type_name, &prefix));
       DO(Consume("]"));
+      TryConsume(":");  // ':' is optional between message labels and values.
       string serialized_value;
       DO(ConsumeAnyValue(full_type_name,
                          message->GetDescriptor()->file()->pool(),
@@ -389,7 +391,6 @@ class TextFormat::Parser::ParserImpl {
           string(prefix + full_type_name));
       reflection->SetString(message, any_value_field, serialized_value);
       return true;
-      // Fall through.
     }
     if (TryConsume("[")) {
       // Extension.
@@ -656,7 +657,7 @@ class TextFormat::Parser::ParserImpl {
       case FieldDescriptor::CPPTYPE_FLOAT: {
         double value;
         DO(ConsumeDouble(&value));
-        SET_FIELD(Float, static_cast<float>(value));
+        SET_FIELD(Float, io::SafeDoubleToFloat(value));
         break;
       }
 
@@ -1357,7 +1358,10 @@ string TextFormat::FieldValuePrinter::PrintDouble(double val) const {
   return SimpleDtoa(val);
 }
 string TextFormat::FieldValuePrinter::PrintString(const string& val) const {
-  return StrCat("\"", CEscape(val), "\"");
+  string printed("\"");
+  CEscapeAndAppend(val, &printed);
+  printed.push_back('\"');
+  return printed;
 }
 string TextFormat::FieldValuePrinter::PrintBytes(const string& val) const {
   return PrintString(val);
@@ -1423,7 +1427,8 @@ TextFormat::Printer::Printer()
     use_short_repeated_primitives_(false),
     hide_unknown_fields_(false),
     print_message_fields_in_index_order_(false),
-    expand_any_(false) {
+    expand_any_(false),
+    truncate_string_field_longer_than_(0LL) {
   SetUseUtf8StringEscaping(false);
 }
 
@@ -1775,11 +1780,21 @@ void TextFormat::Printer::PrintFieldValue(
           ? reflection->GetRepeatedStringReference(
               message, field, index, &scratch)
           : reflection->GetStringReference(message, field, &scratch);
+      int64 size = value.size();
+      if (truncate_string_field_longer_than_ > 0) {
+        size = std::min(truncate_string_field_longer_than_,
+                        static_cast<int64>(value.size()));
+      }
+      string truncated_value(value.substr(0, size) + "...<truncated>...");
+      const string* value_to_print = &value;
+      if (size < value.size()) {
+        value_to_print = &truncated_value;
+      }
       if (field->type() == FieldDescriptor::TYPE_STRING) {
-        generator.Print(printer->PrintString(value));
+        generator.Print(printer->PrintString(*value_to_print));
       } else {
         GOOGLE_DCHECK_EQ(field->type(), FieldDescriptor::TYPE_BYTES);
-        generator.Print(printer->PrintBytes(value));
+        generator.Print(printer->PrintBytes(*value_to_print));
       }
       break;
     }
@@ -1926,14 +1941,10 @@ void TextFormat::Printer::PrintUnknownFields(
         } else {
           // This field is not parseable as a Message.
           // So it is probably just a plain string.
-          generator.Print(": \"");
-          generator.Print(CEscape(value));
-          generator.Print("\"");
-          if (single_line_mode_) {
-            generator.Print(" ");
-          } else {
-            generator.Print("\n");
-          }
+          string printed(": \"");
+          CEscapeAndAppend(value, &printed);
+          printed.append(single_line_mode_ ? "\" " : "\"\n");
+          generator.Print(printed);
         }
         break;
       }
diff --git a/src/google/protobuf/text_format.h b/src/google/protobuf/text_format.h
index 6717aecd..ef3d4a8f 100644
--- a/src/google/protobuf/text_format.h
+++ b/src/google/protobuf/text_format.h
@@ -219,6 +219,18 @@ class LIBPROTOBUF_EXPORT TextFormat {
       expand_any_ = expand;
     }
 
+    // If non-zero, we truncate all string fields that are  longer than this
+    // threshold.  This is useful when the proto message has very long strings,
+    // e.g., dump of encoded image file.
+    //
+    // NOTE(hfgong):  Setting a non-zero value breaks round-trip safe
+    // property of TextFormat::Printer.  That is, from the printed message, we
+    // cannot fully recover the original string field any more.
+    void SetTruncateStringFieldLongerThan(
+        const int64 truncate_string_field_longer_than) {
+      truncate_string_field_longer_than_ = truncate_string_field_longer_than;
+    }
+
     // Register a custom field-specific FieldValuePrinter for fields
     // with a particular FieldDescriptor.
     // Returns "true" if the registration succeeded, or "false", if there is
@@ -286,6 +298,8 @@ class LIBPROTOBUF_EXPORT TextFormat {
 
     bool expand_any_;
 
+    int64 truncate_string_field_longer_than_;
+
     google::protobuf::scoped_ptr<const FieldValuePrinter> default_field_value_printer_;
     typedef map<const FieldDescriptor*,
                 const FieldValuePrinter*> CustomPrinterMap;
diff --git a/src/google/protobuf/timestamp.pb.cc b/src/google/protobuf/timestamp.pb.cc
index f0b09195..c1c4402c 100644
--- a/src/google/protobuf/timestamp.pb.cc
+++ b/src/google/protobuf/timestamp.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
@@ -82,9 +83,9 @@ void protobuf_AddDesc_google_2fprotobuf_2ftimestamp_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\037google/protobuf/timestamp.proto\022\017googl"
     "e.protobuf\"+\n\tTimestamp\022\017\n\007seconds\030\001 \001(\003"
-    "\022\r\n\005nanos\030\002 \001(\005BQ\n\023com.google.protobufB\016"
-    "TimestampProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Proto"
-    "buf.WellKnownTypesb\006proto3", 186);
+    "\022\r\n\005nanos\030\002 \001(\005BT\n\023com.google.protobufB\016"
+    "TimestampProtoP\001\240\001\001\370\001\001\242\002\003GPB\252\002\036Google.Pr"
+    "otobuf.WellKnownTypesb\006proto3", 189);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/timestamp.proto", &protobuf_RegisterTypes);
   Timestamp::default_instance_ = new Timestamp();
@@ -122,6 +123,14 @@ Timestamp::Timestamp()
   // @@protoc_insertion_point(constructor:google.protobuf.Timestamp)
 }
 
+Timestamp::Timestamp(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.Timestamp)
+}
+
 void Timestamp::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -147,10 +156,20 @@ Timestamp::~Timestamp() {
 }
 
 void Timestamp::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void Timestamp::ArenaDtor(void* object) {
+  Timestamp* _this = reinterpret_cast< Timestamp* >(object);
+  (void)_this;
+}
+void Timestamp::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void Timestamp::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -169,11 +188,7 @@ const Timestamp& Timestamp::default_instance() {
 Timestamp* Timestamp::default_instance_ = NULL;
 
 Timestamp* Timestamp::New(::google::protobuf::Arena* arena) const {
-  Timestamp* n = new Timestamp;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<Timestamp>(arena);
 }
 
 void Timestamp::Clear() {
@@ -349,6 +364,18 @@ bool Timestamp::IsInitialized() const {
 
 void Timestamp::Swap(Timestamp* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    Timestamp temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void Timestamp::UnsafeArenaSwap(Timestamp* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void Timestamp::InternalSwap(Timestamp* other) {
diff --git a/src/google/protobuf/timestamp.pb.h b/src/google/protobuf/timestamp.pb.h
index 85fc1242..7bf62597 100644
--- a/src/google/protobuf/timestamp.pb.h
+++ b/src/google/protobuf/timestamp.pb.h
@@ -53,9 +53,14 @@ class LIBPROTOBUF_EXPORT Timestamp : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const Timestamp& default_instance();
 
+  void UnsafeArenaSwap(Timestamp* other);
   void Swap(Timestamp* other);
 
   // implements Message ----------------------------------------------
@@ -82,6 +87,11 @@ class LIBPROTOBUF_EXPORT Timestamp : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(Timestamp* other);
+  protected:
+  explicit Timestamp(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -113,6 +123,9 @@ class LIBPROTOBUF_EXPORT Timestamp : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::int64 seconds_;
   ::google::protobuf::int32 nanos_;
diff --git a/src/google/protobuf/timestamp.proto b/src/google/protobuf/timestamp.proto
index 06b60e6f..b51fc3fa 100644
--- a/src/google/protobuf/timestamp.proto
+++ b/src/google/protobuf/timestamp.proto
@@ -27,15 +27,17 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "TimestampProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option cc_enable_arenas = true;
+option java_package = "com.google.protobuf";
+option java_outer_classname = "TimestampProto";
+option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
 // A Timestamp represents a point in time independent of any time zone
@@ -92,6 +94,7 @@ option objc_class_prefix = "GPB";
 //     nanos = int((now - seconds) * 10**9)
 //     timestamp = Timestamp(seconds=seconds, nanos=nanos)
 //
+//
 message Timestamp {
 
   // Represents seconds of UTC time since Unix epoch
diff --git a/src/google/protobuf/type.pb.cc b/src/google/protobuf/type.pb.cc
index 5792dff2..7b47b3bd 100644
--- a/src/google/protobuf/type.pb.cc
+++ b/src/google/protobuf/type.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
@@ -70,7 +71,7 @@ void protobuf_AssignDesc_google_2fprotobuf_2ftype_2eproto() {
       GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Type, _internal_metadata_),
       GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Type, _is_default_instance_));
   Field_descriptor_ = file->message_type(1);
-  static const int Field_offsets_[9] = {
+  static const int Field_offsets_[10] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, kind_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, cardinality_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, number_),
@@ -80,6 +81,7 @@ void protobuf_AssignDesc_google_2fprotobuf_2ftype_2eproto() {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, packed_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, options_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, json_name_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(Field, default_value_),
   };
   Field_reflection_ =
     ::google::protobuf::internal::GeneratedMessageReflection::NewGeneratedMessageReflection(
@@ -203,37 +205,37 @@ void protobuf_AddDesc_google_2fprotobuf_2ftype_2eproto() {
     "\030\004 \003(\0132\027.google.protobuf.Option\0226\n\016sourc"
     "e_context\030\005 \001(\0132\036.google.protobuf.Source"
     "Context\022\'\n\006syntax\030\006 \001(\0162\027.google.protobu"
-    "f.Syntax\"\276\005\n\005Field\022)\n\004kind\030\001 \001(\0162\033.googl"
+    "f.Syntax\"\325\005\n\005Field\022)\n\004kind\030\001 \001(\0162\033.googl"
     "e.protobuf.Field.Kind\0227\n\013cardinality\030\002 \001"
     "(\0162\".google.protobuf.Field.Cardinality\022\016"
     "\n\006number\030\003 \001(\005\022\014\n\004name\030\004 \001(\t\022\020\n\010type_url"
     "\030\006 \001(\t\022\023\n\013oneof_index\030\007 \001(\005\022\016\n\006packed\030\010 "
     "\001(\010\022(\n\007options\030\t \003(\0132\027.google.protobuf.O"
-    "ption\022\021\n\tjson_name\030\n \001(\t\"\310\002\n\004Kind\022\020\n\014TYP"
-    "E_UNKNOWN\020\000\022\017\n\013TYPE_DOUBLE\020\001\022\016\n\nTYPE_FLO"
-    "AT\020\002\022\016\n\nTYPE_INT64\020\003\022\017\n\013TYPE_UINT64\020\004\022\016\n"
-    "\nTYPE_INT32\020\005\022\020\n\014TYPE_FIXED64\020\006\022\020\n\014TYPE_"
-    "FIXED32\020\007\022\r\n\tTYPE_BOOL\020\010\022\017\n\013TYPE_STRING\020"
-    "\t\022\016\n\nTYPE_GROUP\020\n\022\020\n\014TYPE_MESSAGE\020\013\022\016\n\nT"
-    "YPE_BYTES\020\014\022\017\n\013TYPE_UINT32\020\r\022\r\n\tTYPE_ENU"
-    "M\020\016\022\021\n\rTYPE_SFIXED32\020\017\022\021\n\rTYPE_SFIXED64\020"
-    "\020\022\017\n\013TYPE_SINT32\020\021\022\017\n\013TYPE_SINT64\020\022\"t\n\013C"
-    "ardinality\022\027\n\023CARDINALITY_UNKNOWN\020\000\022\030\n\024C"
-    "ARDINALITY_OPTIONAL\020\001\022\030\n\024CARDINALITY_REQ"
-    "UIRED\020\002\022\030\n\024CARDINALITY_REPEATED\020\003\"\316\001\n\004En"
-    "um\022\014\n\004name\030\001 \001(\t\022-\n\tenumvalue\030\002 \003(\0132\032.go"
-    "ogle.protobuf.EnumValue\022(\n\007options\030\003 \003(\013"
-    "2\027.google.protobuf.Option\0226\n\016source_cont"
-    "ext\030\004 \001(\0132\036.google.protobuf.SourceContex"
-    "t\022\'\n\006syntax\030\005 \001(\0162\027.google.protobuf.Synt"
-    "ax\"S\n\tEnumValue\022\014\n\004name\030\001 \001(\t\022\016\n\006number\030"
-    "\002 \001(\005\022(\n\007options\030\003 \003(\0132\027.google.protobuf"
-    ".Option\";\n\006Option\022\014\n\004name\030\001 \001(\t\022#\n\005value"
-    "\030\002 \001(\0132\024.google.protobuf.Any*.\n\006Syntax\022\021"
-    "\n\rSYNTAX_PROTO2\020\000\022\021\n\rSYNTAX_PROTO3\020\001BL\n\023"
-    "com.google.protobufB\tTypeProtoP\001\240\001\001\242\002\003GP"
-    "B\252\002\036Google.Protobuf.WellKnownTypesb\006prot"
-    "o3", 1522);
+    "ption\022\021\n\tjson_name\030\n \001(\t\022\025\n\rdefault_valu"
+    "e\030\013 \001(\t\"\310\002\n\004Kind\022\020\n\014TYPE_UNKNOWN\020\000\022\017\n\013TY"
+    "PE_DOUBLE\020\001\022\016\n\nTYPE_FLOAT\020\002\022\016\n\nTYPE_INT6"
+    "4\020\003\022\017\n\013TYPE_UINT64\020\004\022\016\n\nTYPE_INT32\020\005\022\020\n\014"
+    "TYPE_FIXED64\020\006\022\020\n\014TYPE_FIXED32\020\007\022\r\n\tTYPE"
+    "_BOOL\020\010\022\017\n\013TYPE_STRING\020\t\022\016\n\nTYPE_GROUP\020\n"
+    "\022\020\n\014TYPE_MESSAGE\020\013\022\016\n\nTYPE_BYTES\020\014\022\017\n\013TY"
+    "PE_UINT32\020\r\022\r\n\tTYPE_ENUM\020\016\022\021\n\rTYPE_SFIXE"
+    "D32\020\017\022\021\n\rTYPE_SFIXED64\020\020\022\017\n\013TYPE_SINT32\020"
+    "\021\022\017\n\013TYPE_SINT64\020\022\"t\n\013Cardinality\022\027\n\023CAR"
+    "DINALITY_UNKNOWN\020\000\022\030\n\024CARDINALITY_OPTION"
+    "AL\020\001\022\030\n\024CARDINALITY_REQUIRED\020\002\022\030\n\024CARDIN"
+    "ALITY_REPEATED\020\003\"\316\001\n\004Enum\022\014\n\004name\030\001 \001(\t\022"
+    "-\n\tenumvalue\030\002 \003(\0132\032.google.protobuf.Enu"
+    "mValue\022(\n\007options\030\003 \003(\0132\027.google.protobu"
+    "f.Option\0226\n\016source_context\030\004 \001(\0132\036.googl"
+    "e.protobuf.SourceContext\022\'\n\006syntax\030\005 \001(\016"
+    "2\027.google.protobuf.Syntax\"S\n\tEnumValue\022\014"
+    "\n\004name\030\001 \001(\t\022\016\n\006number\030\002 \001(\005\022(\n\007options\030"
+    "\003 \003(\0132\027.google.protobuf.Option\";\n\006Option"
+    "\022\014\n\004name\030\001 \001(\t\022#\n\005value\030\002 \001(\0132\024.google.p"
+    "rotobuf.Any*.\n\006Syntax\022\021\n\rSYNTAX_PROTO2\020\000"
+    "\022\021\n\rSYNTAX_PROTO3\020\001BL\n\023com.google.protob"
+    "ufB\tTypeProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Protob"
+    "uf.WellKnownTypesb\006proto3", 1545);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/type.proto", &protobuf_RegisterTypes);
   Type::default_instance_ = new Type();
@@ -1026,6 +1028,7 @@ const int Field::kOneofIndexFieldNumber;
 const int Field::kPackedFieldNumber;
 const int Field::kOptionsFieldNumber;
 const int Field::kJsonNameFieldNumber;
+const int Field::kDefaultValueFieldNumber;
 #endif  // !defined(_MSC_VER) || _MSC_VER >= 1900
 
 Field::Field()
@@ -1058,6 +1061,7 @@ void Field::SharedCtor() {
   oneof_index_ = 0;
   packed_ = false;
   json_name_.UnsafeSetDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  default_value_.UnsafeSetDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 }
 
 Field::~Field() {
@@ -1069,6 +1073,7 @@ void Field::SharedDtor() {
   name_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   type_url_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   json_name_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  default_value_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   if (this != default_instance_) {
   }
 }
@@ -1113,6 +1118,7 @@ void Field::Clear() {
   type_url_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   packed_ = false;
   json_name_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  default_value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 
 #undef ZR_HELPER_
 #undef ZR_
@@ -1270,6 +1276,23 @@ bool Field::MergePartialFromCodedStream(
         } else {
           goto handle_unusual;
         }
+        if (input->ExpectTag(90)) goto parse_default_value;
+        break;
+      }
+
+      // optional string default_value = 11;
+      case 11: {
+        if (tag == 90) {
+         parse_default_value:
+          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
+                input, this->mutable_default_value()));
+          DO_(::google::protobuf::internal::WireFormatLite::VerifyUtf8String(
+            this->default_value().data(), this->default_value().length(),
+            ::google::protobuf::internal::WireFormatLite::PARSE,
+            "google.protobuf.Field.default_value"));
+        } else {
+          goto handle_unusual;
+        }
         if (input->ExpectAtEnd()) goto success;
         break;
       }
@@ -1361,6 +1384,16 @@ void Field::SerializeWithCachedSizes(
       10, this->json_name(), output);
   }
 
+  // optional string default_value = 11;
+  if (this->default_value().size() > 0) {
+    ::google::protobuf::internal::WireFormatLite::VerifyUtf8String(
+      this->default_value().data(), this->default_value().length(),
+      ::google::protobuf::internal::WireFormatLite::SERIALIZE,
+      "google.protobuf.Field.default_value");
+    ::google::protobuf::internal::WireFormatLite::WriteStringMaybeAliased(
+      11, this->default_value(), output);
+  }
+
   // @@protoc_insertion_point(serialize_end:google.protobuf.Field)
 }
 
@@ -1434,6 +1467,17 @@ void Field::SerializeWithCachedSizes(
         10, this->json_name(), target);
   }
 
+  // optional string default_value = 11;
+  if (this->default_value().size() > 0) {
+    ::google::protobuf::internal::WireFormatLite::VerifyUtf8String(
+      this->default_value().data(), this->default_value().length(),
+      ::google::protobuf::internal::WireFormatLite::SERIALIZE,
+      "google.protobuf.Field.default_value");
+    target =
+      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
+        11, this->default_value(), target);
+  }
+
   // @@protoc_insertion_point(serialize_to_array_end:google.protobuf.Field)
   return target;
 }
@@ -1493,6 +1537,13 @@ int Field::ByteSize() const {
         this->json_name());
   }
 
+  // optional string default_value = 11;
+  if (this->default_value().size() > 0) {
+    total_size += 1 +
+      ::google::protobuf::internal::WireFormatLite::StringSize(
+        this->default_value());
+  }
+
   // repeated .google.protobuf.Option options = 9;
   total_size += 1 * this->options_size();
   for (int i = 0; i < this->options_size(); i++) {
@@ -1549,6 +1600,10 @@ void Field::MergeFrom(const Field& from) {
 
     json_name_.AssignWithDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), from.json_name_);
   }
+  if (from.default_value().size() > 0) {
+
+    default_value_.AssignWithDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), from.default_value_);
+  }
 }
 
 void Field::CopyFrom(const ::google::protobuf::Message& from) {
@@ -1582,6 +1637,7 @@ void Field::InternalSwap(Field* other) {
   std::swap(packed_, other->packed_);
   options_.UnsafeArenaSwap(&other->options_);
   json_name_.Swap(&other->json_name_);
+  default_value_.Swap(&other->default_value_);
   _internal_metadata_.Swap(&other->_internal_metadata_);
   std::swap(_cached_size_, other->_cached_size_);
 }
@@ -1826,6 +1882,49 @@ void Field::clear_json_name() {
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.json_name)
 }
 
+// optional string default_value = 11;
+void Field::clear_default_value() {
+  default_value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ const ::std::string& Field::default_value() const {
+  // @@protoc_insertion_point(field_get:google.protobuf.Field.default_value)
+  return default_value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ void Field::set_default_value(const ::std::string& value) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  // @@protoc_insertion_point(field_set:google.protobuf.Field.default_value)
+}
+ void Field::set_default_value(const char* value) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  // @@protoc_insertion_point(field_set_char:google.protobuf.Field.default_value)
+}
+ void Field::set_default_value(const char* value, size_t size) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      ::std::string(reinterpret_cast<const char*>(value), size));
+  // @@protoc_insertion_point(field_set_pointer:google.protobuf.Field.default_value)
+}
+ ::std::string* Field::mutable_default_value() {
+  
+  // @@protoc_insertion_point(field_mutable:google.protobuf.Field.default_value)
+  return default_value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ ::std::string* Field::release_default_value() {
+  
+  return default_value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ void Field::set_allocated_default_value(::std::string* default_value) {
+  if (default_value != NULL) {
+    
+  } else {
+    
+  }
+  default_value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), default_value);
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.default_value)
+}
+
 #endif  // PROTOBUF_INLINE_NOT_IN_HEADERS
 
 // ===================================================================
diff --git a/src/google/protobuf/type.pb.h b/src/google/protobuf/type.pb.h
index 2533eb4e..76fe8a65 100644
--- a/src/google/protobuf/type.pb.h
+++ b/src/google/protobuf/type.pb.h
@@ -471,6 +471,17 @@ class LIBPROTOBUF_EXPORT Field : public ::google::protobuf::Message {
   ::std::string* release_json_name();
   void set_allocated_json_name(::std::string* json_name);
 
+  // optional string default_value = 11;
+  void clear_default_value();
+  static const int kDefaultValueFieldNumber = 11;
+  const ::std::string& default_value() const;
+  void set_default_value(const ::std::string& value);
+  void set_default_value(const char* value);
+  void set_default_value(const char* value, size_t size);
+  ::std::string* mutable_default_value();
+  ::std::string* release_default_value();
+  void set_allocated_default_value(::std::string* default_value);
+
   // @@protoc_insertion_point(class_scope:google.protobuf.Field)
  private:
 
@@ -484,6 +495,7 @@ class LIBPROTOBUF_EXPORT Field : public ::google::protobuf::Message {
   ::google::protobuf::internal::ArenaStringPtr type_url_;
   ::google::protobuf::RepeatedPtrField< ::google::protobuf::Option > options_;
   ::google::protobuf::internal::ArenaStringPtr json_name_;
+  ::google::protobuf::internal::ArenaStringPtr default_value_;
   bool packed_;
   mutable int _cached_size_;
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2ftype_2eproto();
@@ -1264,6 +1276,49 @@ inline void Field::set_allocated_json_name(::std::string* json_name) {
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.json_name)
 }
 
+// optional string default_value = 11;
+inline void Field::clear_default_value() {
+  default_value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline const ::std::string& Field::default_value() const {
+  // @@protoc_insertion_point(field_get:google.protobuf.Field.default_value)
+  return default_value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline void Field::set_default_value(const ::std::string& value) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  // @@protoc_insertion_point(field_set:google.protobuf.Field.default_value)
+}
+inline void Field::set_default_value(const char* value) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  // @@protoc_insertion_point(field_set_char:google.protobuf.Field.default_value)
+}
+inline void Field::set_default_value(const char* value, size_t size) {
+  
+  default_value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      ::std::string(reinterpret_cast<const char*>(value), size));
+  // @@protoc_insertion_point(field_set_pointer:google.protobuf.Field.default_value)
+}
+inline ::std::string* Field::mutable_default_value() {
+  
+  // @@protoc_insertion_point(field_mutable:google.protobuf.Field.default_value)
+  return default_value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline ::std::string* Field::release_default_value() {
+  
+  return default_value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline void Field::set_allocated_default_value(::std::string* default_value) {
+  if (default_value != NULL) {
+    
+  } else {
+    
+  }
+  default_value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), default_value);
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.Field.default_value)
+}
+
 // -------------------------------------------------------------------
 
 // Enum
diff --git a/src/google/protobuf/type.proto b/src/google/protobuf/type.proto
index 4df95762..1c9cf53d 100644
--- a/src/google/protobuf/type.proto
+++ b/src/google/protobuf/type.proto
@@ -27,6 +27,7 @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 syntax = "proto3";
 
 package google.protobuf;
@@ -34,22 +35,22 @@ package google.protobuf;
 import "google/protobuf/any.proto";
 import "google/protobuf/source_context.proto";
 
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option java_package = "com.google.protobuf";
 option java_outer_classname = "TypeProto";
 option java_multiple_files = true;
 option java_generate_equals_and_hash = true;
-option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
-// A light-weight descriptor for a proto message type.
+// A protocol buffer message type.
 message Type {
   // The fully qualified message name.
   string name = 1;
   // The list of fields.
   repeated Field fields = 2;
-  // The list of oneof definitions.
-  repeated string oneofs = 3;  // The list of oneofs declared in this Type
-  // The proto options.
+  // The list of types appearing in `oneof` definitions in this type.
+  repeated string oneofs = 3;
+  // The protocol buffer options.
   repeated Option options = 4;
   // The source context.
   SourceContext source_context = 5;
@@ -57,9 +58,9 @@ message Type {
   Syntax syntax = 6;
 }
 
-// Field represents a single field of a message type.
+// A single field of a message type.
 message Field {
-  // Kind represents a basic field type.
+  // Basic field types.
   enum Kind {
     // Field type unknown.
     TYPE_UNKNOWN        = 0;
@@ -81,7 +82,7 @@ message Field {
     TYPE_BOOL           = 8;
     // Field type string.
     TYPE_STRING         = 9;
-    // Field type group (deprecated proto2 type)
+    // Field type group. Proto2 syntax only, and deprecated.
     TYPE_GROUP          = 10;
     // Field type message.
     TYPE_MESSAGE        = 11;
@@ -101,38 +102,40 @@ message Field {
     TYPE_SINT64         = 18;
   };
 
-  // Cardinality represents whether a field is optional, required, or
-  // repeated.
+  // Whether a field is optional, required, or repeated.
   enum Cardinality {
-    // The field cardinality is unknown. Typically an error condition.
+    // For fields with unknown cardinality.
     CARDINALITY_UNKNOWN = 0;
     // For optional fields.
     CARDINALITY_OPTIONAL = 1;
-    // For required fields. Not used for proto3.
+    // For required fields. Proto2 syntax only.
     CARDINALITY_REQUIRED = 2;
     // For repeated fields.
     CARDINALITY_REPEATED = 3;
   };
 
-  // The field kind.
+  // The field type.
   Kind kind = 1;
-  // The field cardinality, i.e. optional/required/repeated.
+  // The field cardinality.
   Cardinality cardinality = 2;
-  // The proto field number.
+  // The field number.
   int32 number = 3;
   // The field name.
   string name = 4;
-  // The type URL (without the scheme) when the type is MESSAGE or ENUM,
-  // such as `type.googleapis.com/google.protobuf.Empty`.
+  // The field type URL, without the scheme, for message or enumeration
+  // types. Example: `"type.googleapis.com/google.protobuf.Timestamp"`.
   string type_url = 6;
-  // Index in Type.oneofs. Starts at 1. Zero means no oneof mapping.
+  // The index of the field type in `Type.oneofs`, for message or enumeration
+  // types. The first type has index 1; zero means the type is not in the list.
   int32 oneof_index = 7;
   // Whether to use alternative packed wire representation.
   bool packed = 8;
-  // The proto options.
+  // The protocol buffer options.
   repeated Option options = 9;
-  // The JSON name for this field.
+  // The field JSON name.
   string json_name = 10;
+  // The string value of the default value of this field. Proto2 syntax only.
+  string default_value = 11;
 }
 
 // Enum type definition.
@@ -141,7 +144,7 @@ message Enum {
   string name = 1;
   // Enum value definitions.
   repeated EnumValue enumvalue = 2;
-  // Proto options for the enum type.
+  // Protocol buffer options.
   repeated Option options = 3;
   // The source context.
   SourceContext source_context = 4;
@@ -155,22 +158,23 @@ message EnumValue {
   string name = 1;
   // Enum value number.
   int32 number = 2;
-  // Proto options for the enum value.
+  // Protocol buffer options.
   repeated Option options = 3;
 }
 
-// Proto option attached to messages/fields/enums etc.
+// A protocol buffer option, which can be attached to a message, field,
+// enumeration, etc.
 message Option {
-  // Proto option name.
+  // The option's name. For example, `"java_package"`.
   string name = 1;
-  // Proto option value.
+  // The option's value. For example, `"com.google.protobuf"`.
   Any value = 2;
 }
 
-// Syntax specifies the syntax in which a service element was defined.
+// The syntax in which a protocol buffer element is defined.
 enum Syntax {
-  // Syntax "proto2"
+  // Syntax `proto2`.
   SYNTAX_PROTO2 = 0;
-  // Syntax "proto3"
+  // Syntax `proto3`.
   SYNTAX_PROTO3 = 1;
 }
diff --git a/src/google/protobuf/unittest_custom_options.proto b/src/google/protobuf/unittest_custom_options.proto
index d4d6e869..4cc0e362 100644
--- a/src/google/protobuf/unittest_custom_options.proto
+++ b/src/google/protobuf/unittest_custom_options.proto
@@ -392,3 +392,30 @@ message NestedOptionType {
     optional int32 nested_extension = 7912573 [(field_opt2) = 1005];
   }
 }
+
+// Custom message option that has a required enum field.
+// WARNING: this is strongly discouraged!
+message OldOptionType {
+  enum TestEnum {
+    OLD_VALUE = 0;
+  }
+  required TestEnum value = 1;
+}
+
+// Updated version of the custom option above.
+message NewOptionType {
+  enum TestEnum {
+    OLD_VALUE = 0;
+    NEW_VALUE = 1;
+  }
+  required TestEnum value = 1;
+}
+
+extend google.protobuf.MessageOptions {
+  optional OldOptionType required_enum_opt = 106161807;
+}
+
+// Test message using the "required_enum_opt" option defined above.
+message TestMessageWithRequiredEnumOption {
+  option (required_enum_opt) = { value: OLD_VALUE };
+}
diff --git a/src/google/protobuf/util/field_comparator.h b/src/google/protobuf/util/field_comparator.h
index ee676265..8b83c69f 100644
--- a/src/google/protobuf/util/field_comparator.h
+++ b/src/google/protobuf/util/field_comparator.h
@@ -93,7 +93,7 @@ class LIBPROTOBUF_EXPORT FieldComparator {
 
 // Basic implementation of FieldComparator.  Supports four modes of floating
 // point value comparison: exact, approximate using MathUtil::AlmostEqual
-// method, and arbitrarilly precise using MathUtil::WithinFracionOrMargin.
+// method, and arbitrarilly precise using MathUtil::WithinFractionOrMargin.
 class LIBPROTOBUF_EXPORT DefaultFieldComparator : public FieldComparator {
  public:
   enum FloatComparison {
diff --git a/src/google/protobuf/util/field_comparator_test.cc b/src/google/protobuf/util/field_comparator_test.cc
index d3d34602..23f7d51d 100644
--- a/src/google/protobuf/util/field_comparator_test.cc
+++ b/src/google/protobuf/util/field_comparator_test.cc
@@ -35,7 +35,12 @@
 #include <google/protobuf/unittest.pb.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/stubs/mathutil.h>
-
+// This gtest header is put after mathutil.h intentionally. We have to do
+// this because mathutil.h includes mathlimits.h which requires cmath not
+// being included to compile on some versions of gcc:
+//   https://github.com/google/protobuf/blob/818c5eee08840355d70d2f3bdf1a2f17986a5e70/src/google/protobuf/stubs/mathlimits.h#L48
+// and the opensource version gtest.h header includes cmath transitively
+// somehow.
 #include <gtest/gtest.h>
 
 namespace google {
diff --git a/src/google/protobuf/util/internal/datapiece.cc b/src/google/protobuf/util/internal/datapiece.cc
index ea360798..b557429f 100644
--- a/src/google/protobuf/util/internal/datapiece.cc
+++ b/src/google/protobuf/util/internal/datapiece.cc
@@ -35,8 +35,8 @@
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/util/internal/utility.h>
 #include <google/protobuf/stubs/strutil.h>
-#include <google/protobuf/stubs/mathutil.h>
 #include <google/protobuf/stubs/mathlimits.h>
+#include <google/protobuf/stubs/mathutil.h>
 
 namespace google {
 namespace protobuf {
@@ -57,13 +57,8 @@ inline Status InvalidArgument(StringPiece value_str) {
   return Status(util::error::INVALID_ARGUMENT, value_str);
 }
 
-// For general conversion between
-//     int32, int64, uint32, uint64, double and float
-// except conversion between double and float.
 template <typename To, typename From>
-StatusOr<To> NumberConvertAndCheck(From before) {
-  if (::google::protobuf::internal::is_same<From, To>::value) return before;
-  To after = static_cast<To>(before);
+StatusOr<To> ValidateNumberConversion(To after, From before) {
   if (after == before &&
       MathUtil::Sign<From>(before) == MathUtil::Sign<To>(after)) {
     return after;
@@ -76,6 +71,27 @@ StatusOr<To> NumberConvertAndCheck(From before) {
   }
 }
 
+// For general conversion between
+//     int32, int64, uint32, uint64, double and float
+// except conversion between double and float.
+template <typename To, typename From>
+StatusOr<To> NumberConvertAndCheck(From before) {
+  if (::google::protobuf::internal::is_same<From, To>::value) return before;
+
+  To after = static_cast<To>(before);
+  return ValidateNumberConversion(after, before);
+}
+
+// For conversion to integer types (int32, int64, uint32, uint64) from floating
+// point types (double, float) only.
+template <typename To, typename From>
+StatusOr<To> FloatingPointToIntConvertAndCheck(From before) {
+  if (::google::protobuf::internal::is_same<From, To>::value) return before;
+
+  To after = static_cast<To>(before);
+  return ValidateNumberConversion(after, before);
+}
+
 // For conversion between double and float only.
 template <typename To, typename From>
 StatusOr<To> FloatingPointConvertAndCheck(From before) {
@@ -96,30 +112,50 @@ StatusOr<To> FloatingPointConvertAndCheck(From before) {
 }  // namespace
 
 StatusOr<int32> DataPiece::ToInt32() const {
-  if (type_ == TYPE_STRING) {
-    return StringToNumber<int32>(safe_strto32);
-  }
+  if (type_ == TYPE_STRING) return StringToNumber<int32>(safe_strto32);
+
+  if (type_ == TYPE_DOUBLE)
+    return FloatingPointToIntConvertAndCheck<int32, double>(double_);
+
+  if (type_ == TYPE_FLOAT)
+    return FloatingPointToIntConvertAndCheck<int32, float>(float_);
+
   return GenericConvert<int32>();
 }
 
 StatusOr<uint32> DataPiece::ToUint32() const {
-  if (type_ == TYPE_STRING) {
-    return StringToNumber<uint32>(safe_strtou32);
-  }
+  if (type_ == TYPE_STRING) return StringToNumber<uint32>(safe_strtou32);
+
+  if (type_ == TYPE_DOUBLE)
+    return FloatingPointToIntConvertAndCheck<uint32, double>(double_);
+
+  if (type_ == TYPE_FLOAT)
+    return FloatingPointToIntConvertAndCheck<uint32, float>(float_);
+
   return GenericConvert<uint32>();
 }
 
 StatusOr<int64> DataPiece::ToInt64() const {
-  if (type_ == TYPE_STRING) {
-    return StringToNumber<int64>(safe_strto64);
-  }
+  if (type_ == TYPE_STRING) return StringToNumber<int64>(safe_strto64);
+
+  if (type_ == TYPE_DOUBLE)
+    return FloatingPointToIntConvertAndCheck<int64, double>(double_);
+
+  if (type_ == TYPE_FLOAT)
+    return FloatingPointToIntConvertAndCheck<int64, float>(float_);
+
   return GenericConvert<int64>();
 }
 
 StatusOr<uint64> DataPiece::ToUint64() const {
-  if (type_ == TYPE_STRING) {
-    return StringToNumber<uint64>(safe_strtou64);
-  }
+  if (type_ == TYPE_STRING) return StringToNumber<uint64>(safe_strtou64);
+
+  if (type_ == TYPE_DOUBLE)
+    return FloatingPointToIntConvertAndCheck<uint64, double>(double_);
+
+  if (type_ == TYPE_FLOAT)
+    return FloatingPointToIntConvertAndCheck<uint64, float>(float_);
+
   return GenericConvert<uint64>();
 }
 
diff --git a/src/google/protobuf/util/internal/datapiece.h b/src/google/protobuf/util/internal/datapiece.h
index 2ab3fa88..f22bfe70 100644
--- a/src/google/protobuf/util/internal/datapiece.h
+++ b/src/google/protobuf/util/internal/datapiece.h
@@ -98,7 +98,8 @@ class LIBPROTOBUF_EXPORT DataPiece {
 
   static DataPiece NullData() { return DataPiece(TYPE_NULL, 0); }
 
-  virtual ~DataPiece() {}
+  virtual ~DataPiece() {
+  }
 
   // Accessors
   Type type() const { return type_; }
diff --git a/src/google/protobuf/util/internal/default_value_objectwriter.cc b/src/google/protobuf/util/internal/default_value_objectwriter.cc
index 97b248ff..a63e560d 100644
--- a/src/google/protobuf/util/internal/default_value_objectwriter.cc
+++ b/src/google/protobuf/util/internal/default_value_objectwriter.cc
@@ -33,6 +33,7 @@
 #include <google/protobuf/stubs/hash.h>
 
 #include <google/protobuf/util/internal/constants.h>
+#include <google/protobuf/util/internal/utility.h>
 #include <google/protobuf/stubs/map_util.h>
 
 namespace google {
@@ -42,13 +43,25 @@ using util::Status;
 using util::StatusOr;
 namespace converter {
 
+namespace {
+// Helper function to convert string value to given data type by calling the
+// passed converter function on the DataPiece created from "value" argument.
+// If value is empty or if conversion fails, the default_value is returned.
+template <typename T>
+T ConvertTo(StringPiece value, StatusOr<T> (DataPiece::*converter_fn)() const,
+            T default_value) {
+  if (value.empty()) return default_value;
+  StatusOr<T> result = (DataPiece(value).*converter_fn)();
+  return result.ok() ? result.ValueOrDie() : default_value;
+}
+}  // namespace
+
 DefaultValueObjectWriter::DefaultValueObjectWriter(
     TypeResolver* type_resolver, const google::protobuf::Type& type,
     ObjectWriter* ow)
     : typeinfo_(TypeInfo::NewTypeInfo(type_resolver)),
       own_typeinfo_(true),
       type_(type),
-      disable_normalize_(false),
       current_(NULL),
       root_(NULL),
       ow_(ow) {}
@@ -165,12 +178,6 @@ DefaultValueObjectWriter* DefaultValueObjectWriter::RenderNull(
   return this;
 }
 
-DefaultValueObjectWriter*
-DefaultValueObjectWriter::DisableCaseNormalizationForNextKey() {
-  disable_normalize_ = true;
-  return this;
-}
-
 DefaultValueObjectWriter::Node::Node(const string& name,
                                      const google::protobuf::Type* type,
                                      NodeKind kind, const DataPiece& data,
@@ -178,7 +185,6 @@ DefaultValueObjectWriter::Node::Node(const string& name,
     : name_(name),
       type_(type),
       kind_(kind),
-      disable_normalize_(false),
       is_any_(false),
       data_(data),
       is_placeholder_(is_placeholder) {}
@@ -198,10 +204,6 @@ DefaultValueObjectWriter::Node* DefaultValueObjectWriter::Node::FindChild(
 }
 
 void DefaultValueObjectWriter::Node::WriteTo(ObjectWriter* ow) {
-  if (disable_normalize_) {
-    ow->DisableCaseNormalizationForNextKey();
-  }
-
   if (kind_ == PRIMITIVE) {
     ObjectWriter::RenderDataPieceTo(data_, name_, ow);
     return;
@@ -324,6 +326,7 @@ void DefaultValueObjectWriter::Node::PopulateChildren(
         }
       }
     }
+
     if (!is_map &&
         field.cardinality() ==
             google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
@@ -336,11 +339,11 @@ void DefaultValueObjectWriter::Node::PopulateChildren(
 
     // If the child field is of primitive type, sets its data to the default
     // value of its type.
-    google::protobuf::scoped_ptr<Node> child(
-        new Node(field.json_name(), field_type, kind,
-                 kind == PRIMITIVE ? CreateDefaultDataPieceForField(field)
-                                   : DataPiece::NullData(),
-                 true));
+    google::protobuf::scoped_ptr<Node> child(new Node(
+        field.json_name(), field_type, kind,
+        kind == PRIMITIVE ? CreateDefaultDataPieceForField(field, typeinfo)
+                          : DataPiece::NullData(),
+        true));
     new_children.push_back(child.release());
   }
   // Adds all leftover nodes in children_ to the beginning of new_child.
@@ -363,41 +366,68 @@ void DefaultValueObjectWriter::MaybePopulateChildrenOfAny(Node* node) {
   }
 }
 
+DataPiece DefaultValueObjectWriter::FindEnumDefault(
+    const google::protobuf::Field& field, const TypeInfo* typeinfo) {
+  if (!field.default_value().empty()) return DataPiece(field.default_value());
+
+  const google::protobuf::Enum* enum_type =
+      typeinfo->GetEnumByTypeUrl(field.type_url());
+  if (!enum_type) {
+    GOOGLE_LOG(WARNING) << "Could not find enum with type '" << field.type_url()
+                 << "'";
+    return DataPiece::NullData();
+  }
+  // We treat the first value as the default if none is specified.
+  return enum_type->enumvalue_size() > 0
+             ? DataPiece(enum_type->enumvalue(0).name())
+             : DataPiece::NullData();
+}
+
 DataPiece DefaultValueObjectWriter::CreateDefaultDataPieceForField(
-    const google::protobuf::Field& field) {
+    const google::protobuf::Field& field, const TypeInfo* typeinfo) {
   switch (field.kind()) {
     case google::protobuf::Field_Kind_TYPE_DOUBLE: {
-      return DataPiece(static_cast<double>(0));
+      return DataPiece(ConvertTo<double>(
+          field.default_value(), &DataPiece::ToDouble, static_cast<double>(0)));
     }
     case google::protobuf::Field_Kind_TYPE_FLOAT: {
-      return DataPiece(static_cast<float>(0));
+      return DataPiece(ConvertTo<float>(
+          field.default_value(), &DataPiece::ToFloat, static_cast<float>(0)));
     }
     case google::protobuf::Field_Kind_TYPE_INT64:
     case google::protobuf::Field_Kind_TYPE_SINT64:
     case google::protobuf::Field_Kind_TYPE_SFIXED64: {
-      return DataPiece(static_cast<int64>(0));
+      return DataPiece(ConvertTo<int64>(
+          field.default_value(), &DataPiece::ToInt64, static_cast<int64>(0)));
     }
     case google::protobuf::Field_Kind_TYPE_UINT64:
     case google::protobuf::Field_Kind_TYPE_FIXED64: {
-      return DataPiece(static_cast<uint64>(0));
+      return DataPiece(ConvertTo<uint64>(
+          field.default_value(), &DataPiece::ToUint64, static_cast<uint64>(0)));
     }
     case google::protobuf::Field_Kind_TYPE_INT32:
     case google::protobuf::Field_Kind_TYPE_SINT32:
     case google::protobuf::Field_Kind_TYPE_SFIXED32: {
-      return DataPiece(static_cast<int32>(0));
+      return DataPiece(ConvertTo<int32>(
+          field.default_value(), &DataPiece::ToInt32, static_cast<int32>(0)));
     }
     case google::protobuf::Field_Kind_TYPE_BOOL: {
-      return DataPiece(false);
+      return DataPiece(
+          ConvertTo<bool>(field.default_value(), &DataPiece::ToBool, false));
     }
     case google::protobuf::Field_Kind_TYPE_STRING: {
-      return DataPiece(string());
+      return DataPiece(field.default_value());
     }
     case google::protobuf::Field_Kind_TYPE_BYTES: {
-      return DataPiece("", false);
+      return DataPiece(field.default_value(), false);
     }
     case google::protobuf::Field_Kind_TYPE_UINT32:
     case google::protobuf::Field_Kind_TYPE_FIXED32: {
-      return DataPiece(static_cast<uint32>(0));
+      return DataPiece(ConvertTo<uint32>(
+          field.default_value(), &DataPiece::ToUint32, static_cast<uint32>(0)));
+    }
+    case google::protobuf::Field_Kind_TYPE_ENUM: {
+      return FindEnumDefault(field, typeinfo);
     }
     default: { return DataPiece::NullData(); }
   }
@@ -408,7 +438,6 @@ DefaultValueObjectWriter* DefaultValueObjectWriter::StartObject(
   if (current_ == NULL) {
     root_.reset(new Node(name.ToString(), &type_, OBJECT, DataPiece::NullData(),
                          false));
-    root_->set_disable_normalize(GetAndResetDisableNormalize());
     root_->PopulateChildren(typeinfo_);
     current_ = root_.get();
     return this;
@@ -428,7 +457,6 @@ DefaultValueObjectWriter* DefaultValueObjectWriter::StartObject(
   }
 
   child->set_is_placeholder(false);
-  child->set_disable_normalize(GetAndResetDisableNormalize());
   if (child->kind() == OBJECT && child->number_of_children() == 0) {
     child->PopulateChildren(typeinfo_);
   }
@@ -454,21 +482,18 @@ DefaultValueObjectWriter* DefaultValueObjectWriter::StartList(
   if (current_ == NULL) {
     root_.reset(
         new Node(name.ToString(), &type_, LIST, DataPiece::NullData(), false));
-    root_->set_disable_normalize(GetAndResetDisableNormalize());
     current_ = root_.get();
     return this;
   }
   MaybePopulateChildrenOfAny(current_);
   Node* child = current_->FindChild(name);
   if (child == NULL || child->kind() != LIST) {
-    GOOGLE_LOG(WARNING) << "Cannot find field '" << name << "'.";
     google::protobuf::scoped_ptr<Node> node(
         new Node(name.ToString(), NULL, LIST, DataPiece::NullData(), false));
     child = node.get();
     current_->AddChild(node.release());
   }
   child->set_is_placeholder(false);
-  child->set_disable_normalize(GetAndResetDisableNormalize());
 
   stack_.push(current_);
   current_ = child;
@@ -526,7 +551,6 @@ void DefaultValueObjectWriter::RenderDataPiece(StringPiece name,
   } else {
     child->set_data(data);
   }
-  child->set_disable_normalize(GetAndResetDisableNormalize());
 }
 
 }  // namespace converter
diff --git a/src/google/protobuf/util/internal/default_value_objectwriter.h b/src/google/protobuf/util/internal/default_value_objectwriter.h
index bcb526e8..695b9dd8 100644
--- a/src/google/protobuf/util/internal/default_value_objectwriter.h
+++ b/src/google/protobuf/util/internal/default_value_objectwriter.h
@@ -98,8 +98,6 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
 
   virtual DefaultValueObjectWriter* RenderNull(StringPiece name);
 
-  virtual DefaultValueObjectWriter* DisableCaseNormalizationForNextKey();
-
  private:
   enum NodeKind {
     PRIMITIVE = 0,
@@ -149,10 +147,6 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
 
     void set_data(const DataPiece& data) { data_ = data; }
 
-    void set_disable_normalize(bool disable_normalize) {
-      disable_normalize_ = disable_normalize;
-    }
-
     bool is_any() { return is_any_; }
 
     void set_is_any(bool is_any) { is_any_ = is_any; }
@@ -176,8 +170,6 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
     const google::protobuf::Type* type_;
     // The kind of this node.
     NodeKind kind_;
-    // Whether to disable case normalization of the name.
-    bool disable_normalize_;
     // Whether this is a node for "Any".
     bool is_any_;
     // The data of this node when it is a leaf node.
@@ -201,16 +193,17 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
 
   // Creates a DataPiece containing the default value of the type of the field.
   static DataPiece CreateDefaultDataPieceForField(
-      const google::protobuf::Field& field);
-
-  // Returns disable_normalize_ and reset it to false.
-  bool GetAndResetDisableNormalize() {
-    return disable_normalize_ ? (disable_normalize_ = false, true) : false;
-  }
+      const google::protobuf::Field& field, const TypeInfo* typeinfo);
 
   // Adds or replaces the data_ of a primitive child node.
   void RenderDataPiece(StringPiece name, const DataPiece& data);
 
+  // Returns the default enum value as a DataPiece, or the first enum value if
+  // there is no default. For proto3, where we cannot specify an explicit
+  // default, a zero value will always be returned.
+  static DataPiece FindEnumDefault(const google::protobuf::Field& field,
+                                   const TypeInfo* typeinfo);
+
   // Type information for all the types used in the descriptor. Used to find
   // google::protobuf::Type of nested messages/enums.
   const TypeInfo* typeinfo_;
@@ -221,8 +214,6 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
   // Holds copies of strings passed to RenderString.
   vector<string*> string_values_;
 
-  // Whether to disable case normalization of the next node.
-  bool disable_normalize_;
   // The current Node. Owned by its parents.
   Node* current_;
   // The root Node.
diff --git a/src/google/protobuf/util/internal/default_value_objectwriter_test.cc b/src/google/protobuf/util/internal/default_value_objectwriter_test.cc
index 237d0722..b7a537ab 100644
--- a/src/google/protobuf/util/internal/default_value_objectwriter_test.cc
+++ b/src/google/protobuf/util/internal/default_value_objectwriter_test.cc
@@ -43,21 +43,19 @@ namespace testing {
 
 using google::protobuf::testing::DefaultValueTest;
 
-// Tests to cover some basic DefaultValueObjectWriter use cases. More tests are
-// in the marshalling_test.cc and translator_integration_test.cc.
-class DefaultValueObjectWriterTest
+// Base class for setting up required state for running default values tests on
+// different descriptors.
+class BaseDefaultValueObjectWriterTest
     : public ::testing::TestWithParam<testing::TypeInfoSource> {
  protected:
-  DefaultValueObjectWriterTest()
+  explicit BaseDefaultValueObjectWriterTest(const Descriptor* descriptor)
       : helper_(GetParam()), mock_(), expects_(&mock_) {
-    helper_.ResetTypeInfo(DefaultValueTest::descriptor());
+    helper_.ResetTypeInfo(descriptor);
     testing_.reset(helper_.NewDefaultValueWriter(
-        string(kTypeServiceBaseUrl) + "/" +
-            DefaultValueTest::descriptor()->full_name(),
-        &mock_));
+        string(kTypeServiceBaseUrl) + "/" + descriptor->full_name(), &mock_));
   }
 
-  virtual ~DefaultValueObjectWriterTest() {}
+  ~BaseDefaultValueObjectWriterTest() override {}
 
   TypeInfoTestHelper helper_;
   MockObjectWriter mock_;
@@ -65,6 +63,15 @@ class DefaultValueObjectWriterTest
   google::protobuf::scoped_ptr<DefaultValueObjectWriter> testing_;
 };
 
+// Tests to cover some basic DefaultValueObjectWriter use cases. More tests are
+// in the marshalling_test.cc and translator_integration_test.cc.
+class DefaultValueObjectWriterTest : public BaseDefaultValueObjectWriterTest {
+ protected:
+  DefaultValueObjectWriterTest()
+      : BaseDefaultValueObjectWriterTest(DefaultValueTest::descriptor()) {}
+  ~DefaultValueObjectWriterTest() override {}
+};
+
 INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
                         DefaultValueObjectWriterTest,
                         ::testing::Values(
@@ -74,6 +81,8 @@ TEST_P(DefaultValueObjectWriterTest, Empty) {
   // Set expectation
   expects_.StartObject("")
       ->RenderDouble("doubleValue", 0.0)
+      ->StartList("repeatedDouble")
+      ->EndList()
       ->RenderFloat("floatValue", 0.0)
       ->RenderInt64("int64Value", 0)
       ->RenderUint64("uint64Value", 0)
@@ -82,6 +91,7 @@ TEST_P(DefaultValueObjectWriterTest, Empty) {
       ->RenderBool("boolValue", false)
       ->RenderString("stringValue", "")
       ->RenderBytes("bytesValue", "")
+      ->RenderString("enumValue", "ENUM_FIRST")
       ->EndObject();
 
   // Actual testing
@@ -92,6 +102,8 @@ TEST_P(DefaultValueObjectWriterTest, NonDefaultDouble) {
   // Set expectation
   expects_.StartObject("")
       ->RenderDouble("doubleValue", 1.0)
+      ->StartList("repeatedDouble")
+      ->EndList()
       ->RenderFloat("floatValue", 0.0)
       ->RenderInt64("int64Value", 0)
       ->RenderUint64("uint64Value", 0)
@@ -99,6 +111,7 @@ TEST_P(DefaultValueObjectWriterTest, NonDefaultDouble) {
       ->RenderUint32("uint32Value", 0)
       ->RenderBool("boolValue", false)
       ->RenderString("stringValue", "")
+      ->RenderString("enumValue", "ENUM_FIRST")
       ->EndObject();
 
   // Actual testing
@@ -109,6 +122,8 @@ TEST_P(DefaultValueObjectWriterTest, ShouldRetainUnknownField) {
   // Set expectation
   expects_.StartObject("")
       ->RenderDouble("doubleValue", 1.0)
+      ->StartList("repeatedDouble")
+      ->EndList()
       ->RenderFloat("floatValue", 0.0)
       ->RenderInt64("int64Value", 0)
       ->RenderUint64("uint64Value", 0)
@@ -120,6 +135,7 @@ TEST_P(DefaultValueObjectWriterTest, ShouldRetainUnknownField) {
       ->StartObject("unknownObject")
       ->RenderString("unknown", "def")
       ->EndObject()
+      ->RenderString("enumValue", "ENUM_FIRST")
       ->EndObject();
 
   // Actual testing
@@ -132,6 +148,7 @@ TEST_P(DefaultValueObjectWriterTest, ShouldRetainUnknownField) {
       ->EndObject();
 }
 
+
 }  // namespace testing
 }  // namespace converter
 }  // namespace util
diff --git a/src/google/protobuf/util/internal/error_listener.h b/src/google/protobuf/util/internal/error_listener.h
index 2699684d..3f063936 100644
--- a/src/google/protobuf/util/internal/error_listener.h
+++ b/src/google/protobuf/util/internal/error_listener.h
@@ -31,11 +31,13 @@
 #ifndef GOOGLE_PROTOBUF_UTIL_CONVERTER_ERROR_LISTENER_H__
 #define GOOGLE_PROTOBUF_UTIL_CONVERTER_ERROR_LISTENER_H__
 
+#include <algorithm>
 #include <memory>
 #ifndef _SHARED_PTR_H
 #include <google/protobuf/stubs/shared_ptr.h>
 #endif
 #include <string>
+#include <vector>
 
 #include <google/protobuf/stubs/callback.h>
 #include <google/protobuf/stubs/common.h>
diff --git a/src/google/protobuf/util/internal/json_objectwriter_test.cc b/src/google/protobuf/util/internal/json_objectwriter_test.cc
index dcd60601..9d820162 100644
--- a/src/google/protobuf/util/internal/json_objectwriter_test.cc
+++ b/src/google/protobuf/util/internal/json_objectwriter_test.cc
@@ -47,8 +47,7 @@ class JsonObjectWriterTest : public ::testing::Test {
   JsonObjectWriterTest()
       : str_stream_(new StringOutputStream(&output_)),
         out_stream_(new CodedOutputStream(str_stream_)),
-        ow_(NULL) {
-  }
+        ow_(NULL) {}
 
   virtual ~JsonObjectWriterTest() {
     delete ow_;
@@ -64,36 +63,34 @@ class JsonObjectWriterTest : public ::testing::Test {
 
 TEST_F(JsonObjectWriterTest, EmptyRootObject) {
   ow_ = new JsonObjectWriter("", out_stream_);
-  ow_->StartObject("")
-     ->EndObject();
+  ow_->StartObject("")->EndObject();
   EXPECT_EQ("{}", output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, EmptyObject) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartObject("")
-       ->RenderString("test", "value")
-       ->StartObject("empty")
-       ->EndObject()
-     ->EndObject();
+      ->RenderString("test", "value")
+      ->StartObject("empty")
+      ->EndObject()
+      ->EndObject();
   EXPECT_EQ("{\"test\":\"value\",\"empty\":{}}",
             output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, EmptyRootList) {
   ow_ = new JsonObjectWriter("", out_stream_);
-  ow_->StartList("")
-     ->EndList();
+  ow_->StartList("")->EndList();
   EXPECT_EQ("[]", output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, EmptyList) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartObject("")
-       ->RenderString("test", "value")
-       ->StartList("empty")
-       ->EndList()
-     ->EndObject();
+      ->RenderString("test", "value")
+      ->StartList("empty")
+      ->EndList()
+      ->EndObject();
   EXPECT_EQ("{\"test\":\"value\",\"empty\":[]}",
             output_.substr(0, out_stream_->ByteCount()));
 }
@@ -101,10 +98,10 @@ TEST_F(JsonObjectWriterTest, EmptyList) {
 TEST_F(JsonObjectWriterTest, ObjectInObject) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartObject("")
-       ->StartObject("nested")
-         ->RenderString("field", "value")
-       ->EndObject()
-     ->EndObject();
+      ->StartObject("nested")
+      ->RenderString("field", "value")
+      ->EndObject()
+      ->EndObject();
   EXPECT_EQ("{\"nested\":{\"field\":\"value\"}}",
             output_.substr(0, out_stream_->ByteCount()));
 }
@@ -112,10 +109,10 @@ TEST_F(JsonObjectWriterTest, ObjectInObject) {
 TEST_F(JsonObjectWriterTest, ListInObject) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartObject("")
-       ->StartList("nested")
-         ->RenderString("", "value")
-       ->EndList()
-     ->EndObject();
+      ->StartList("nested")
+      ->RenderString("", "value")
+      ->EndList()
+      ->EndObject();
   EXPECT_EQ("{\"nested\":[\"value\"]}",
             output_.substr(0, out_stream_->ByteCount()));
 }
@@ -123,10 +120,10 @@ TEST_F(JsonObjectWriterTest, ListInObject) {
 TEST_F(JsonObjectWriterTest, ObjectInList) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartList("")
-       ->StartObject("")
-         ->RenderString("field", "value")
-       ->EndObject()
-     ->EndList();
+      ->StartObject("")
+      ->RenderString("field", "value")
+      ->EndObject()
+      ->EndList();
   EXPECT_EQ("[{\"field\":\"value\"}]",
             output_.substr(0, out_stream_->ByteCount()));
 }
@@ -134,10 +131,10 @@ TEST_F(JsonObjectWriterTest, ObjectInList) {
 TEST_F(JsonObjectWriterTest, ListInList) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartList("")
-       ->StartList("")
-         ->RenderString("", "value")
-       ->EndList()
-     ->EndList();
+      ->StartList("")
+      ->RenderString("", "value")
+      ->EndList()
+      ->EndList();
   EXPECT_EQ("[[\"value\"]]", output_.substr(0, out_stream_->ByteCount()));
 }
 
@@ -156,14 +153,18 @@ TEST_F(JsonObjectWriterTest, RenderPrimitives) {
       ->EndObject();
   EXPECT_EQ(
       "{\"bool\":true,"
-      "\"double\":" + ValueAsString<double>(1.7976931348623157e+308) + ","
-      "\"float\":" + ValueAsString<float>(3.4028235e+38) + ","
-      "\"int\":-2147483648,"
-      "\"long\":\"-9223372036854775808\","
-      "\"bytes\":\"YWJyYWNhZGFicmE=\","
-      "\"string\":\"string\","
-      "\"emptybytes\":\"\","
-      "\"emptystring\":\"\"}",
+      "\"double\":" +
+          ValueAsString<double>(std::numeric_limits<double>::max()) +
+          ","
+          "\"float\":" +
+          ValueAsString<float>(std::numeric_limits<float>::max()) +
+          ","
+          "\"int\":-2147483648,"
+          "\"long\":\"-9223372036854775808\","
+          "\"bytes\":\"YWJyYWNhZGFicmE=\","
+          "\"string\":\"string\","
+          "\"emptybytes\":\"\","
+          "\"emptystring\":\"\"}",
       output_.substr(0, out_stream_->ByteCount()));
 }
 
@@ -181,81 +182,83 @@ TEST_F(JsonObjectWriterTest, BytesEncodesAsNonWebSafeBase64) {
 TEST_F(JsonObjectWriterTest, PrettyPrintList) {
   ow_ = new JsonObjectWriter(" ", out_stream_);
   ow_->StartObject("")
-       ->StartList("items")
-         ->RenderString("", "item1")
-         ->RenderString("", "item2")
-         ->RenderString("", "item3")
-       ->EndList()
-       ->StartList("empty")
-       ->EndList()
-     ->EndObject();
-  EXPECT_EQ("{\n"
-            " \"items\": [\n"
-            "  \"item1\",\n"
-            "  \"item2\",\n"
-            "  \"item3\"\n"
-            " ],\n"
-            " \"empty\": []\n"
-            "}\n",
-            output_.substr(0, out_stream_->ByteCount()));
+      ->StartList("items")
+      ->RenderString("", "item1")
+      ->RenderString("", "item2")
+      ->RenderString("", "item3")
+      ->EndList()
+      ->StartList("empty")
+      ->EndList()
+      ->EndObject();
+  EXPECT_EQ(
+      "{\n"
+      " \"items\": [\n"
+      "  \"item1\",\n"
+      "  \"item2\",\n"
+      "  \"item3\"\n"
+      " ],\n"
+      " \"empty\": []\n"
+      "}\n",
+      output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, PrettyPrintObject) {
   ow_ = new JsonObjectWriter(" ", out_stream_);
   ow_->StartObject("")
-       ->StartObject("items")
-         ->RenderString("key1", "item1")
-         ->RenderString("key2", "item2")
-         ->RenderString("key3", "item3")
-       ->EndObject()
-       ->StartObject("empty")
-       ->EndObject()
-     ->EndObject();
-  EXPECT_EQ("{\n"
-            " \"items\": {\n"
-            "  \"key1\": \"item1\",\n"
-            "  \"key2\": \"item2\",\n"
-            "  \"key3\": \"item3\"\n"
-            " },\n"
-            " \"empty\": {}\n"
-            "}\n",
-            output_.substr(0, out_stream_->ByteCount()));
+      ->StartObject("items")
+      ->RenderString("key1", "item1")
+      ->RenderString("key2", "item2")
+      ->RenderString("key3", "item3")
+      ->EndObject()
+      ->StartObject("empty")
+      ->EndObject()
+      ->EndObject();
+  EXPECT_EQ(
+      "{\n"
+      " \"items\": {\n"
+      "  \"key1\": \"item1\",\n"
+      "  \"key2\": \"item2\",\n"
+      "  \"key3\": \"item3\"\n"
+      " },\n"
+      " \"empty\": {}\n"
+      "}\n",
+      output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, PrettyPrintEmptyObjectInEmptyList) {
   ow_ = new JsonObjectWriter(" ", out_stream_);
   ow_->StartObject("")
-       ->StartList("list")
-         ->StartObject("")
-         ->EndObject()
-       ->EndList()
-     ->EndObject();
-  EXPECT_EQ("{\n"
-            " \"list\": [\n"
-            "  {}\n"
-            " ]\n"
-            "}\n",
-            output_.substr(0, out_stream_->ByteCount()));
+      ->StartList("list")
+      ->StartObject("")
+      ->EndObject()
+      ->EndList()
+      ->EndObject();
+  EXPECT_EQ(
+      "{\n"
+      " \"list\": [\n"
+      "  {}\n"
+      " ]\n"
+      "}\n",
+      output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, PrettyPrintDoubleIndent) {
   ow_ = new JsonObjectWriter("  ", out_stream_);
   ow_->StartObject("")
-       ->RenderBool("bool", true)
-       ->RenderInt32("int", 42)
-     ->EndObject();
-  EXPECT_EQ("{\n"
-            "  \"bool\": true,\n"
-            "  \"int\": 42\n"
-            "}\n",
-            output_.substr(0, out_stream_->ByteCount()));
+      ->RenderBool("bool", true)
+      ->RenderInt32("int", 42)
+      ->EndObject();
+  EXPECT_EQ(
+      "{\n"
+      "  \"bool\": true,\n"
+      "  \"int\": 42\n"
+      "}\n",
+      output_.substr(0, out_stream_->ByteCount()));
 }
 
 TEST_F(JsonObjectWriterTest, StringsEscapedAndEnclosedInDoubleQuotes) {
   ow_ = new JsonObjectWriter("", out_stream_);
-  ow_->StartObject("")
-       ->RenderString("string", "'<>&amp;\\\"\r\n")
-     ->EndObject();
+  ow_->StartObject("")->RenderString("string", "'<>&amp;\\\"\r\n")->EndObject();
   EXPECT_EQ("{\"string\":\"'\\u003c\\u003e&amp;\\\\\\\"\\r\\n\"}",
             output_.substr(0, out_stream_->ByteCount()));
 }
@@ -263,13 +266,13 @@ TEST_F(JsonObjectWriterTest, StringsEscapedAndEnclosedInDoubleQuotes) {
 TEST_F(JsonObjectWriterTest, Stringification) {
   ow_ = new JsonObjectWriter("", out_stream_);
   ow_->StartObject("")
-       ->RenderDouble("double_nan", std::numeric_limits<double>::quiet_NaN())
-       ->RenderFloat("float_nan", std::numeric_limits<float>::quiet_NaN())
-       ->RenderDouble("double_pos", std::numeric_limits<double>::infinity())
-       ->RenderFloat("float_pos", std::numeric_limits<float>::infinity())
-       ->RenderDouble("double_neg", -std::numeric_limits<double>::infinity())
-       ->RenderFloat("float_neg", -std::numeric_limits<float>::infinity())
-     ->EndObject();
+      ->RenderDouble("double_nan", std::numeric_limits<double>::quiet_NaN())
+      ->RenderFloat("float_nan", std::numeric_limits<float>::quiet_NaN())
+      ->RenderDouble("double_pos", std::numeric_limits<double>::infinity())
+      ->RenderFloat("float_pos", std::numeric_limits<float>::infinity())
+      ->RenderDouble("double_neg", -std::numeric_limits<double>::infinity())
+      ->RenderFloat("float_neg", -std::numeric_limits<float>::infinity())
+      ->EndObject();
   EXPECT_EQ(
       "{\"double_nan\":\"NaN\","
       "\"float_nan\":\"NaN\","
diff --git a/src/google/protobuf/util/internal/json_stream_parser.cc b/src/google/protobuf/util/internal/json_stream_parser.cc
index a7ef7fe2..df916751 100644
--- a/src/google/protobuf/util/internal/json_stream_parser.cc
+++ b/src/google/protobuf/util/internal/json_stream_parser.cc
@@ -157,10 +157,10 @@ util::Status JsonStreamParser::FinishParse() {
     char* coerced = internal::UTF8CoerceToStructurallyValid(leftover_, utf8.get(), ' ');
     p_ = json_ = StringPiece(coerced, leftover_.size());
   } else {
+    p_ = json_ = leftover_;
     if (!internal::IsStructurallyValidUTF8(leftover_)) {
       return ReportFailure("Encountered non UTF-8 code points.");
     }
-    p_ = json_ = leftover_;
   }
 
   // Parse the remainder in finishing mode, which reports errors for things like
diff --git a/src/google/protobuf/util/internal/json_stream_parser_test.cc b/src/google/protobuf/util/internal/json_stream_parser_test.cc
index c833ed1f..3414826e 100644
--- a/src/google/protobuf/util/internal/json_stream_parser_test.cc
+++ b/src/google/protobuf/util/internal/json_stream_parser_test.cc
@@ -348,6 +348,7 @@ TEST_F(JsonStreamParserTest, RejectNonUtf8WhenNotCoerced) {
   for (int i = 0; i <= json.length(); ++i) {
     DoErrorTest(json, i, "Encountered non UTF-8 code points.");
   }
+  DoErrorTest("\xFF{}", 0, "Encountered non UTF-8 code points.");
 }
 
 #ifndef _MSC_VER
diff --git a/src/google/protobuf/util/internal/object_writer.h b/src/google/protobuf/util/internal/object_writer.h
index 20bd3627..e695f45e 100644
--- a/src/google/protobuf/util/internal/object_writer.h
+++ b/src/google/protobuf/util/internal/object_writer.h
@@ -101,11 +101,6 @@ class LIBPROTOBUF_EXPORT ObjectWriter {
   // Renders a Null value.
   virtual ObjectWriter* RenderNull(StringPiece name) = 0;
 
-  // Disables case normalization. Any RenderTYPE call after calling this
-  // function will output the name field as-is. No normalization is attempted on
-  // it. This setting is reset immediately after the next RenderTYPE is called.
-  virtual ObjectWriter* DisableCaseNormalizationForNextKey() { return this; }
-
   // Renders a DataPiece object to a ObjectWriter.
   static void RenderDataPieceTo(const DataPiece& data, StringPiece name,
                                 ObjectWriter* ow);
diff --git a/src/google/protobuf/util/internal/proto_writer.cc b/src/google/protobuf/util/internal/proto_writer.cc
new file mode 100644
index 00000000..47e0009e
--- /dev/null
+++ b/src/google/protobuf/util/internal/proto_writer.cc
@@ -0,0 +1,744 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <google/protobuf/util/internal/proto_writer.h>
+
+#include <functional>
+#include <stack>
+
+#include <google/protobuf/stubs/once.h>
+#include <google/protobuf/stubs/time.h>
+#include <google/protobuf/wire_format_lite.h>
+#include <google/protobuf/util/internal/field_mask_utility.h>
+#include <google/protobuf/util/internal/object_location_tracker.h>
+#include <google/protobuf/util/internal/constants.h>
+#include <google/protobuf/util/internal/utility.h>
+#include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/map_util.h>
+#include <google/protobuf/stubs/statusor.h>
+
+
+namespace google {
+namespace protobuf {
+namespace util {
+namespace converter {
+
+using google::protobuf::internal::WireFormatLite;
+using google::protobuf::io::CodedOutputStream;
+using util::error::INVALID_ARGUMENT;
+using util::Status;
+using util::StatusOr;
+
+
+ProtoWriter::ProtoWriter(TypeResolver* type_resolver,
+                         const google::protobuf::Type& type,
+                         strings::ByteSink* output, ErrorListener* listener)
+    : master_type_(type),
+      typeinfo_(TypeInfo::NewTypeInfo(type_resolver)),
+      own_typeinfo_(true),
+      done_(false),
+      element_(NULL),
+      size_insert_(),
+      output_(output),
+      buffer_(),
+      adapter_(&buffer_),
+      stream_(new CodedOutputStream(&adapter_)),
+      listener_(listener),
+      invalid_depth_(0),
+      tracker_(new ObjectLocationTracker()) {}
+
+ProtoWriter::ProtoWriter(const TypeInfo* typeinfo,
+                         const google::protobuf::Type& type,
+                         strings::ByteSink* output, ErrorListener* listener)
+    : master_type_(type),
+      typeinfo_(typeinfo),
+      own_typeinfo_(false),
+      done_(false),
+      element_(NULL),
+      size_insert_(),
+      output_(output),
+      buffer_(),
+      adapter_(&buffer_),
+      stream_(new CodedOutputStream(&adapter_)),
+      listener_(listener),
+      invalid_depth_(0),
+      tracker_(new ObjectLocationTracker()) {}
+
+ProtoWriter::~ProtoWriter() {
+  if (own_typeinfo_) {
+    delete typeinfo_;
+  }
+  if (element_ == NULL) return;
+  // Cleanup explicitly in order to avoid destructor stack overflow when input
+  // is deeply nested.
+  // Cast to BaseElement to avoid doing additional checks (like missing fields)
+  // during pop().
+  google::protobuf::scoped_ptr<BaseElement> element(
+      static_cast<BaseElement*>(element_.get())->pop<BaseElement>());
+  while (element != NULL) {
+    element.reset(element->pop<BaseElement>());
+  }
+}
+
+namespace {
+
+// Writes an INT32 field, including tag to the stream.
+inline Status WriteInt32(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteInt32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// writes an SFIXED32 field, including tag, to the stream.
+inline Status WriteSFixed32(int field_number, const DataPiece& data,
+                            CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteSFixed32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// Writes an SINT32 field, including tag, to the stream.
+inline Status WriteSInt32(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<int32> i32 = data.ToInt32();
+  if (i32.ok()) {
+    WireFormatLite::WriteSInt32(field_number, i32.ValueOrDie(), stream);
+  }
+  return i32.status();
+}
+
+// Writes a FIXED32 field, including tag, to the stream.
+inline Status WriteFixed32(int field_number, const DataPiece& data,
+                           CodedOutputStream* stream) {
+  StatusOr<uint32> u32 = data.ToUint32();
+  if (u32.ok()) {
+    WireFormatLite::WriteFixed32(field_number, u32.ValueOrDie(), stream);
+  }
+  return u32.status();
+}
+
+// Writes a UINT32 field, including tag, to the stream.
+inline Status WriteUInt32(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<uint32> u32 = data.ToUint32();
+  if (u32.ok()) {
+    WireFormatLite::WriteUInt32(field_number, u32.ValueOrDie(), stream);
+  }
+  return u32.status();
+}
+
+// Writes an INT64 field, including tag, to the stream.
+inline Status WriteInt64(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteInt64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes an SFIXED64 field, including tag, to the stream.
+inline Status WriteSFixed64(int field_number, const DataPiece& data,
+                            CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteSFixed64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes an SINT64 field, including tag, to the stream.
+inline Status WriteSInt64(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<int64> i64 = data.ToInt64();
+  if (i64.ok()) {
+    WireFormatLite::WriteSInt64(field_number, i64.ValueOrDie(), stream);
+  }
+  return i64.status();
+}
+
+// Writes a FIXED64 field, including tag, to the stream.
+inline Status WriteFixed64(int field_number, const DataPiece& data,
+                           CodedOutputStream* stream) {
+  StatusOr<uint64> u64 = data.ToUint64();
+  if (u64.ok()) {
+    WireFormatLite::WriteFixed64(field_number, u64.ValueOrDie(), stream);
+  }
+  return u64.status();
+}
+
+// Writes a UINT64 field, including tag, to the stream.
+inline Status WriteUInt64(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<uint64> u64 = data.ToUint64();
+  if (u64.ok()) {
+    WireFormatLite::WriteUInt64(field_number, u64.ValueOrDie(), stream);
+  }
+  return u64.status();
+}
+
+// Writes a DOUBLE field, including tag, to the stream.
+inline Status WriteDouble(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<double> d = data.ToDouble();
+  if (d.ok()) {
+    WireFormatLite::WriteDouble(field_number, d.ValueOrDie(), stream);
+  }
+  return d.status();
+}
+
+// Writes a FLOAT field, including tag, to the stream.
+inline Status WriteFloat(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<float> f = data.ToFloat();
+  if (f.ok()) {
+    WireFormatLite::WriteFloat(field_number, f.ValueOrDie(), stream);
+  }
+  return f.status();
+}
+
+// Writes a BOOL field, including tag, to the stream.
+inline Status WriteBool(int field_number, const DataPiece& data,
+                        CodedOutputStream* stream) {
+  StatusOr<bool> b = data.ToBool();
+  if (b.ok()) {
+    WireFormatLite::WriteBool(field_number, b.ValueOrDie(), stream);
+  }
+  return b.status();
+}
+
+// Writes a BYTES field, including tag, to the stream.
+inline Status WriteBytes(int field_number, const DataPiece& data,
+                         CodedOutputStream* stream) {
+  StatusOr<string> c = data.ToBytes();
+  if (c.ok()) {
+    WireFormatLite::WriteBytes(field_number, c.ValueOrDie(), stream);
+  }
+  return c.status();
+}
+
+// Writes a STRING field, including tag, to the stream.
+inline Status WriteString(int field_number, const DataPiece& data,
+                          CodedOutputStream* stream) {
+  StatusOr<string> s = data.ToString();
+  if (s.ok()) {
+    WireFormatLite::WriteString(field_number, s.ValueOrDie(), stream);
+  }
+  return s.status();
+}
+
+// Writes an ENUM field, including tag, to the stream.
+inline Status WriteEnum(int field_number, const DataPiece& data,
+                        const google::protobuf::Enum* enum_type,
+                        CodedOutputStream* stream) {
+  StatusOr<int> e = data.ToEnum(enum_type);
+  if (e.ok()) {
+    WireFormatLite::WriteEnum(field_number, e.ValueOrDie(), stream);
+  }
+  return e.status();
+}
+
+// Given a google::protobuf::Type, returns the set of all required fields.
+std::set<const google::protobuf::Field*> GetRequiredFields(
+    const google::protobuf::Type& type) {
+  std::set<const google::protobuf::Field*> required;
+  for (int i = 0; i < type.fields_size(); i++) {
+    const google::protobuf::Field& field = type.fields(i);
+    if (field.cardinality() ==
+        google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
+      required.insert(&field);
+    }
+  }
+  return required;
+}
+
+}  // namespace
+
+ProtoWriter::ProtoElement::ProtoElement(const TypeInfo* typeinfo,
+                                        const google::protobuf::Type& type,
+                                        ProtoWriter* enclosing)
+    : BaseElement(NULL),
+      ow_(enclosing),
+      parent_field_(NULL),
+      typeinfo_(typeinfo),
+      type_(type),
+      required_fields_(GetRequiredFields(type)),
+      size_index_(-1),
+      array_index_(-1) {}
+
+ProtoWriter::ProtoElement::ProtoElement(ProtoWriter::ProtoElement* parent,
+                                        const google::protobuf::Field* field,
+                                        const google::protobuf::Type& type,
+                                        bool is_list)
+    : BaseElement(parent),
+      ow_(this->parent()->ow_),
+      parent_field_(field),
+      typeinfo_(this->parent()->typeinfo_),
+      type_(type),
+      size_index_(
+          !is_list && field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE
+              ? ow_->size_insert_.size()
+              : -1),
+      array_index_(is_list ? 0 : -1) {
+  if (!is_list) {
+    if (ow_->IsRepeated(*field)) {
+      // Update array_index_ if it is an explicit list.
+      if (this->parent()->array_index_ >= 0) this->parent()->array_index_++;
+    } else {
+      this->parent()->RegisterField(field);
+    }
+
+    if (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
+      required_fields_ = GetRequiredFields(type_);
+      int start_pos = ow_->stream_->ByteCount();
+      // length of serialized message is the final buffer position minus
+      // starting buffer position, plus length adjustments for size fields
+      // of any nested messages. We start with -start_pos here, so we only
+      // need to add the final buffer position to it at the end.
+      SizeInfo info = {start_pos, -start_pos};
+      ow_->size_insert_.push_back(info);
+    }
+  }
+}
+
+ProtoWriter::ProtoElement* ProtoWriter::ProtoElement::pop() {
+  // Calls the registered error listener for any required field(s) not yet
+  // seen.
+  for (set<const google::protobuf::Field*>::iterator it =
+           required_fields_.begin();
+       it != required_fields_.end(); ++it) {
+    ow_->MissingField((*it)->name());
+  }
+  // Computes the total number of proto bytes used by a message, also adjusts
+  // the size of all parent messages by the length of this size field.
+  // If size_index_ < 0, this is not a message, so no size field is added.
+  if (size_index_ >= 0) {
+    // Add the final buffer position to compute the total length of this
+    // serialized message. The stored value (before this addition) already
+    // contains the total length of the size fields of all nested messages
+    // minus the initial buffer position.
+    ow_->size_insert_[size_index_].size += ow_->stream_->ByteCount();
+    // Calculate the length required to serialize the size field of the
+    // message, and propagate this additional size information upward to
+    // all enclosing messages.
+    int size = ow_->size_insert_[size_index_].size;
+    int length = CodedOutputStream::VarintSize32(size);
+    for (ProtoElement* e = parent(); e != NULL; e = e->parent()) {
+      // Only nested messages have size field, lists do not have size field.
+      if (e->size_index_ >= 0) {
+        ow_->size_insert_[e->size_index_].size += length;
+      }
+    }
+  }
+  return BaseElement::pop<ProtoElement>();
+}
+
+void ProtoWriter::ProtoElement::RegisterField(
+    const google::protobuf::Field* field) {
+  if (!required_fields_.empty() &&
+      field->cardinality() ==
+          google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
+    required_fields_.erase(field);
+  }
+}
+
+string ProtoWriter::ProtoElement::ToString() const {
+  if (parent() == NULL) return "";
+  string loc = parent()->ToString();
+  if (!ow_->IsRepeated(*parent_field_) ||
+      parent()->parent_field_ != parent_field_) {
+    string name = parent_field_->name();
+    int i = 0;
+    while (i < name.size() && (ascii_isalnum(name[i]) || name[i] == '_')) ++i;
+    if (i > 0 && i == name.size()) {  // safe field name
+      if (loc.empty()) {
+        loc = name;
+      } else {
+        StrAppend(&loc, ".", name);
+      }
+    } else {
+      StrAppend(&loc, "[\"", CEscape(name), "\"]");
+    }
+  }
+  if (ow_->IsRepeated(*parent_field_) && array_index_ > 0) {
+    StrAppend(&loc, "[", array_index_ - 1, "]");
+  }
+  return loc.empty() ? "." : loc;
+}
+
+bool ProtoWriter::ProtoElement::IsOneofIndexTaken(int32 index) {
+  return ContainsKey(oneof_indices_, index);
+}
+
+void ProtoWriter::ProtoElement::TakeOneofIndex(int32 index) {
+  InsertIfNotPresent(&oneof_indices_, index);
+}
+
+void ProtoWriter::InvalidName(StringPiece unknown_name, StringPiece message) {
+  listener_->InvalidName(location(), ToSnakeCase(unknown_name), message);
+}
+
+void ProtoWriter::InvalidValue(StringPiece type_name, StringPiece value) {
+  listener_->InvalidValue(location(), type_name, value);
+}
+
+void ProtoWriter::MissingField(StringPiece missing_name) {
+  listener_->MissingField(location(), missing_name);
+}
+
+ProtoWriter* ProtoWriter::StartObject(StringPiece name) {
+  // Starting the root message. Create the root ProtoElement and return.
+  if (element_ == NULL) {
+    if (!name.empty()) {
+      InvalidName(name, "Root element should not be named.");
+    }
+    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+    return this;
+  }
+
+  const google::protobuf::Field* field = NULL;
+  field = BeginNamed(name, false);
+  if (field == NULL) return this;
+
+  // Check to see if this field is a oneof and that no oneof in that group has
+  // already been set.
+  if (!ValidOneof(*field, name)) {
+    ++invalid_depth_;
+    return this;
+  }
+
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    ++invalid_depth_;
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+    WriteTag(*field);
+  element_.reset(new ProtoElement(element_.release(), field, *type, false));
+  return this;
+}
+
+ProtoWriter* ProtoWriter::EndObject() {
+  if (invalid_depth_ > 0) {
+    --invalid_depth_;
+    return this;
+  }
+
+  if (element_ != NULL) {
+    element_.reset(element_->pop());
+  }
+
+
+  // If ending the root element,
+  // then serialize the full message with calculated sizes.
+  if (element_ == NULL) {
+    WriteRootMessage();
+  }
+  return this;
+}
+
+ProtoWriter* ProtoWriter::StartList(StringPiece name) {
+  const google::protobuf::Field* field = BeginNamed(name, true);
+  if (field == NULL) return this;
+
+  if (!ValidOneof(*field, name)) {
+    ++invalid_depth_;
+    return this;
+  }
+
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    ++invalid_depth_;
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+  element_.reset(new ProtoElement(element_.release(), field, *type, true));
+  return this;
+}
+
+ProtoWriter* ProtoWriter::EndList() {
+  if (invalid_depth_ > 0) {
+    --invalid_depth_;
+  } else if (element_ != NULL) {
+    element_.reset(element_->pop());
+  }
+  return this;
+}
+
+ProtoWriter* ProtoWriter::RenderDataPiece(StringPiece name,
+                                          const DataPiece& data) {
+  Status status;
+  if (invalid_depth_ > 0) return this;
+
+  const google::protobuf::Field* field = Lookup(name);
+  if (field == NULL) return this;
+
+  if (!ValidOneof(*field, name)) return this;
+
+  const google::protobuf::Type* type = LookupType(field);
+  if (type == NULL) {
+    InvalidName(name,
+                StrCat("Missing descriptor for field: ", field->type_url()));
+    return this;
+  }
+
+  // Pushing a ProtoElement and then pop it off at the end for 2 purposes:
+  // error location reporting and required field accounting.
+  element_.reset(new ProtoElement(element_.release(), field, *type, false));
+
+  if (field->kind() == google::protobuf::Field_Kind_TYPE_UNKNOWN ||
+      field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
+    InvalidValue(field->type_url().empty()
+                     ? google::protobuf::Field_Kind_Name(field->kind())
+                     : field->type_url(),
+                 data.ValueAsStringOrDefault(""));
+    element_.reset(element()->pop());
+    return this;
+  }
+
+  switch (field->kind()) {
+    case google::protobuf::Field_Kind_TYPE_INT32: {
+      status = WriteInt32(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SFIXED32: {
+      status = WriteSFixed32(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SINT32: {
+      status = WriteSInt32(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FIXED32: {
+      status = WriteFixed32(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_UINT32: {
+      status = WriteUInt32(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_INT64: {
+      status = WriteInt64(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SFIXED64: {
+      status = WriteSFixed64(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_SINT64: {
+      status = WriteSInt64(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FIXED64: {
+      status = WriteFixed64(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_UINT64: {
+      status = WriteUInt64(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_DOUBLE: {
+      status = WriteDouble(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_FLOAT: {
+      status = WriteFloat(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_BOOL: {
+      status = WriteBool(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_BYTES: {
+      status = WriteBytes(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_STRING: {
+      status = WriteString(field->number(), data, stream_.get());
+      break;
+    }
+    case google::protobuf::Field_Kind_TYPE_ENUM: {
+      status = WriteEnum(field->number(), data,
+                         typeinfo_->GetEnumByTypeUrl(field->type_url()),
+                         stream_.get());
+      break;
+    }
+    default:  // TYPE_GROUP or TYPE_MESSAGE
+      status = Status(INVALID_ARGUMENT, data.ToString().ValueOrDie());
+  }
+
+  if (!status.ok()) {
+    InvalidValue(google::protobuf::Field_Kind_Name(field->kind()),
+                 status.error_message());
+  }
+
+  element_.reset(element()->pop());
+  return this;
+}
+
+bool ProtoWriter::ValidOneof(const google::protobuf::Field& field,
+                             StringPiece unnormalized_name) {
+  if (element_ == NULL) return true;
+
+  if (field.oneof_index() > 0) {
+    if (element_->IsOneofIndexTaken(field.oneof_index())) {
+      InvalidValue(
+          "oneof",
+          StrCat("oneof field '",
+                 element_->type().oneofs(field.oneof_index() - 1),
+                 "' is already set. Cannot set '", unnormalized_name, "'"));
+      return false;
+    }
+    element_->TakeOneofIndex(field.oneof_index());
+  }
+  return true;
+}
+
+bool ProtoWriter::IsRepeated(const google::protobuf::Field& field) {
+  return field.cardinality() ==
+         google::protobuf::Field_Cardinality_CARDINALITY_REPEATED;
+}
+
+const google::protobuf::Field* ProtoWriter::BeginNamed(StringPiece name,
+                                                       bool is_list) {
+  if (invalid_depth_ > 0) {
+    ++invalid_depth_;
+    return NULL;
+  }
+  const google::protobuf::Field* field = Lookup(name);
+  if (field == NULL) {
+    ++invalid_depth_;
+    // InvalidName() already called in Lookup().
+    return NULL;
+  }
+  if (is_list && !IsRepeated(*field)) {
+    ++invalid_depth_;
+    InvalidName(name, "Proto field is not repeating, cannot start list.");
+    return NULL;
+  }
+  return field;
+}
+
+const google::protobuf::Field* ProtoWriter::Lookup(
+    StringPiece unnormalized_name) {
+  ProtoElement* e = element();
+  if (e == NULL) {
+    InvalidName(unnormalized_name, "Root element must be a message.");
+    return NULL;
+  }
+  if (unnormalized_name.empty()) {
+    // Objects in repeated field inherit the same field descriptor.
+    if (e->parent_field() == NULL) {
+      InvalidName(unnormalized_name, "Proto fields must have a name.");
+    } else if (!IsRepeated(*e->parent_field())) {
+      InvalidName(unnormalized_name, "Proto fields must have a name.");
+      return NULL;
+    }
+    return e->parent_field();
+  }
+  const google::protobuf::Field* field =
+      typeinfo_->FindField(&e->type(), unnormalized_name);
+  if (field == NULL) InvalidName(unnormalized_name, "Cannot find field.");
+  return field;
+}
+
+const google::protobuf::Type* ProtoWriter::LookupType(
+    const google::protobuf::Field* field) {
+  return ((field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE ||
+           field->kind() == google::protobuf::Field_Kind_TYPE_GROUP)
+              ? typeinfo_->GetTypeByTypeUrl(field->type_url())
+              : &element_->type());
+}
+
+void ProtoWriter::WriteRootMessage() {
+  GOOGLE_DCHECK(!done_);
+  int curr_pos = 0;
+  // Calls the destructor of CodedOutputStream to remove any uninitialized
+  // memory from the Cord before we read it.
+  stream_.reset(NULL);
+  const void* data;
+  int length;
+  google::protobuf::io::ArrayInputStream input_stream(buffer_.data(), buffer_.size());
+  while (input_stream.Next(&data, &length)) {
+    if (length == 0) continue;
+    int num_bytes = length;
+    // Write up to where we need to insert the size field.
+    // The number of bytes we may write is the smaller of:
+    //   - the current fragment size
+    //   - the distance to the next position where a size field needs to be
+    //     inserted.
+    if (!size_insert_.empty() &&
+        size_insert_.front().pos - curr_pos < num_bytes) {
+      num_bytes = size_insert_.front().pos - curr_pos;
+    }
+    output_->Append(static_cast<const char*>(data), num_bytes);
+    if (num_bytes < length) {
+      input_stream.BackUp(length - num_bytes);
+    }
+    curr_pos += num_bytes;
+    // Insert the size field.
+    //   size_insert_.front():      the next <index, size> pair to be written.
+    //   size_insert_.front().pos:  position of the size field.
+    //   size_insert_.front().size: the size (integer) to be inserted.
+    if (!size_insert_.empty() && curr_pos == size_insert_.front().pos) {
+      // Varint32 occupies at most 10 bytes.
+      uint8 insert_buffer[10];
+      uint8* insert_buffer_pos = CodedOutputStream::WriteVarint32ToArray(
+          size_insert_.front().size, insert_buffer);
+      output_->Append(reinterpret_cast<const char*>(insert_buffer),
+                      insert_buffer_pos - insert_buffer);
+      size_insert_.pop_front();
+    }
+  }
+  output_->Flush();
+  stream_.reset(new CodedOutputStream(&adapter_));
+  done_ = true;
+}
+
+void ProtoWriter::WriteTag(const google::protobuf::Field& field) {
+  WireFormatLite::WireType wire_type = WireFormatLite::WireTypeForFieldType(
+      static_cast<WireFormatLite::FieldType>(field.kind()));
+  stream_->WriteTag(WireFormatLite::MakeTag(field.number(), wire_type));
+}
+
+
+}  // namespace converter
+}  // namespace util
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/util/internal/proto_writer.h b/src/google/protobuf/util/internal/proto_writer.h
new file mode 100644
index 00000000..e631e56f
--- /dev/null
+++ b/src/google/protobuf/util/internal/proto_writer.h
@@ -0,0 +1,315 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef GOOGLE_PROTOBUF_UTIL_CONVERTER_PROTO_WRITER_H__
+#define GOOGLE_PROTOBUF_UTIL_CONVERTER_PROTO_WRITER_H__
+
+#include <deque>
+#include <google/protobuf/stubs/hash.h>
+#include <string>
+
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/io/coded_stream.h>
+#include <google/protobuf/io/zero_copy_stream_impl.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/util/internal/type_info.h>
+#include <google/protobuf/util/internal/datapiece.h>
+#include <google/protobuf/util/internal/error_listener.h>
+#include <google/protobuf/util/internal/structured_objectwriter.h>
+#include <google/protobuf/util/type_resolver.h>
+#include <google/protobuf/stubs/bytestream.h>
+
+namespace google {
+namespace protobuf {
+namespace io {
+class CodedOutputStream;
+}  // namespace io
+}  // namespace protobuf
+
+
+namespace protobuf {
+class Type;
+class Field;
+}  // namespace protobuf
+
+
+namespace protobuf {
+namespace util {
+namespace converter {
+
+class ObjectLocationTracker;
+
+// An ObjectWriter that can write protobuf bytes directly from writer events.
+// This class does not support special types like Struct or Map. However, since
+// this class supports raw protobuf, it can be used to provide support for
+// special types by inheriting from it or by wrapping it.
+//
+// It also supports streaming.
+class LIBPROTOBUF_EXPORT ProtoWriter : public StructuredObjectWriter {
+ public:
+// Constructor. Does not take ownership of any parameter passed in.
+  ProtoWriter(TypeResolver* type_resolver, const google::protobuf::Type& type,
+              strings::ByteSink* output, ErrorListener* listener);
+  virtual ~ProtoWriter();
+
+  // ObjectWriter methods.
+  virtual ProtoWriter* StartObject(StringPiece name);
+  virtual ProtoWriter* EndObject();
+  virtual ProtoWriter* StartList(StringPiece name);
+  virtual ProtoWriter* EndList();
+  virtual ProtoWriter* RenderBool(StringPiece name, bool value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderInt32(StringPiece name, int32 value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderUint32(StringPiece name, uint32 value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderInt64(StringPiece name, int64 value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderUint64(StringPiece name, uint64 value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderDouble(StringPiece name, double value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderFloat(StringPiece name, float value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderString(StringPiece name, StringPiece value) {
+    return RenderDataPiece(name, DataPiece(value));
+  }
+  virtual ProtoWriter* RenderBytes(StringPiece name, StringPiece value) {
+    return RenderDataPiece(name, DataPiece(value, false));
+  }
+  virtual ProtoWriter* RenderNull(StringPiece name) {
+    return RenderDataPiece(name, DataPiece::NullData());
+  }
+
+  // Renders a DataPiece 'value' into a field whose wire type is determined
+  // from the given field 'name'.
+  virtual ProtoWriter* RenderDataPiece(StringPiece name,
+                                       const DataPiece& value);
+
+  // Returns the location tracker to use for tracking locations for errors.
+  const LocationTrackerInterface& location() {
+    return element_ != NULL ? *element_ : *tracker_;
+  }
+
+  // When true, we finished writing to output a complete message.
+  bool done() const { return done_; }
+
+  // Returns the proto stream object.
+  google::protobuf::io::CodedOutputStream* stream() { return stream_.get(); }
+
+  // Getters and mutators of invalid_depth_.
+  void IncrementInvalidDepth() { ++invalid_depth_; }
+  void DecrementInvalidDepth() { --invalid_depth_; }
+  int invalid_depth() { return invalid_depth_; }
+
+  ErrorListener* listener() { return listener_; }
+
+  const TypeInfo* typeinfo() { return typeinfo_; }
+
+ protected:
+  class LIBPROTOBUF_EXPORT ProtoElement : public BaseElement, public LocationTrackerInterface {
+   public:
+    // Constructor for the root element. No parent nor field.
+    ProtoElement(const TypeInfo* typeinfo, const google::protobuf::Type& type,
+                 ProtoWriter* enclosing);
+
+    // Constructor for a field of an element.
+    ProtoElement(ProtoElement* parent, const google::protobuf::Field* field,
+                 const google::protobuf::Type& type, bool is_list);
+
+    virtual ~ProtoElement() {}
+
+    // Called just before the destructor for clean up:
+    //   - reports any missing required fields
+    //   - computes the space needed by the size field, and augment the
+    //     length of all parent messages by this additional space.
+    //   - releases and returns the parent pointer.
+    ProtoElement* pop();
+
+    // Accessors
+    // parent_field() may be NULL if we are at root.
+    const google::protobuf::Field* parent_field() const {
+      return parent_field_;
+    }
+    const google::protobuf::Type& type() const { return type_; }
+
+    // Registers field for accounting required fields.
+    void RegisterField(const google::protobuf::Field* field);
+
+    // To report location on error messages.
+    virtual string ToString() const;
+
+    virtual ProtoElement* parent() const {
+      return static_cast<ProtoElement*>(BaseElement::parent());
+    }
+
+    // Returns true if the index is already taken by a preceeding oneof input.
+    bool IsOneofIndexTaken(int32 index);
+
+    // Marks the oneof 'index' as taken. Future inputs to this oneof will
+    // generate an error.
+    void TakeOneofIndex(int32 index);
+
+   private:
+    // Used for access to variables of the enclosing instance of
+    // ProtoWriter.
+    ProtoWriter* ow_;
+
+    // Describes the element as a field in the parent message.
+    // parent_field_ is NULL if and only if this element is the root element.
+    const google::protobuf::Field* parent_field_;
+
+    // TypeInfo to lookup types.
+    const TypeInfo* typeinfo_;
+
+    // Additional variables if this element is a message:
+    // (Root element is always a message).
+    // type_             : the type of this element.
+    // required_fields_  : set of required fields.
+    // size_index_       : index into ProtoWriter::size_insert_
+    //                     for later insertion of serialized message length.
+    const google::protobuf::Type& type_;
+    std::set<const google::protobuf::Field*> required_fields_;
+    const int size_index_;
+
+    // Tracks position in repeated fields, needed for LocationTrackerInterface.
+    int array_index_;
+
+    // Set of oneof indices already seen for the type_. Used to validate
+    // incoming messages so no more than one oneof is set.
+    hash_set<int32> oneof_indices_;
+
+    GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoElement);
+  };
+
+  // Container for inserting 'size' information at the 'pos' position.
+  struct SizeInfo {
+    const int pos;
+    int size;
+  };
+
+  ProtoWriter(const TypeInfo* typeinfo, const google::protobuf::Type& type,
+              strings::ByteSink* output, ErrorListener* listener);
+
+  virtual ProtoElement* element() { return element_.get(); }
+
+  // Helper methods for calling ErrorListener. See error_listener.h.
+  void InvalidName(StringPiece unknown_name, StringPiece message);
+  void InvalidValue(StringPiece type_name, StringPiece value);
+  void MissingField(StringPiece missing_name);
+
+  // Common code for BeginObject() and BeginList() that does invalid_depth_
+  // bookkeeping associated with name lookup.
+  const google::protobuf::Field* BeginNamed(StringPiece name, bool is_list);
+
+  // Lookup the field in the current element. Looks in the base descriptor
+  // and in any extension. This will report an error if the field cannot be
+  // found or if multiple matching extensions are found.
+  const google::protobuf::Field* Lookup(StringPiece name);
+
+  // Lookup the field type in the type descriptor. Returns NULL if the type
+  // is not known.
+  const google::protobuf::Type* LookupType(
+      const google::protobuf::Field* field);
+
+  // Write serialized output to the final output ByteSink, inserting all
+  // the size information for nested messages that are missing from the
+  // intermediate Cord buffer.
+  void WriteRootMessage();
+
+  // Helper method to write proto tags based on the given field.
+  void WriteTag(const google::protobuf::Field& field);
+
+
+  // Returns true if the field for type_ can be set as a oneof. If field is not
+  // a oneof type, this function does nothing and returns true.
+  // If another field for this oneof is already set, this function returns
+  // false. It also calls the appropriate error callback.
+  // unnormalized_name is used for error string.
+  bool ValidOneof(const google::protobuf::Field& field,
+                  StringPiece unnormalized_name);
+
+  // Returns true if the field is repeated.
+  bool IsRepeated(const google::protobuf::Field& field);
+
+ private:
+  // Variables for describing the structure of the input tree:
+  // master_type_: descriptor for the whole protobuf message.
+  // typeinfo_ : the TypeInfo object to lookup types.
+  const google::protobuf::Type& master_type_;
+  const TypeInfo* typeinfo_;
+  // Whether we own the typeinfo_ object.
+  bool own_typeinfo_;
+
+  // Indicates whether we finished writing root message completely.
+  bool done_;
+
+  // Variable for internal state processing:
+  // element_    : the current element.
+  // size_insert_: sizes of nested messages.
+  //               pos  - position to insert the size field.
+  //               size - size value to be inserted.
+  google::protobuf::scoped_ptr<ProtoElement> element_;
+  std::deque<SizeInfo> size_insert_;
+
+  // Variables for output generation:
+  // output_  : pointer to an external ByteSink for final user-visible output.
+  // buffer_  : buffer holding partial message before being ready for output_.
+  // adapter_ : internal adapter between CodedOutputStream and buffer_.
+  // stream_  : wrapper for writing tags and other encodings in wire format.
+  strings::ByteSink* output_;
+  string buffer_;
+  google::protobuf::io::StringOutputStream adapter_;
+  google::protobuf::scoped_ptr<google::protobuf::io::CodedOutputStream> stream_;
+
+  // Variables for error tracking and reporting:
+  // listener_     : a place to report any errors found.
+  // invalid_depth_: number of enclosing invalid nested messages.
+  // tracker_      : the root location tracker interface.
+  ErrorListener* listener_;
+  int invalid_depth_;
+  google::protobuf::scoped_ptr<LocationTrackerInterface> tracker_;
+
+  GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoWriter);
+};
+
+}  // namespace converter
+}  // namespace util
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_UTIL_CONVERTER_PROTO_WRITER_H__
diff --git a/src/google/protobuf/util/internal/protostream_objectsource.cc b/src/google/protobuf/util/internal/protostream_objectsource.cc
index 2bbb1597..034d616f 100644
--- a/src/google/protobuf/util/internal/protostream_objectsource.cc
+++ b/src/google/protobuf/util/internal/protostream_objectsource.cc
@@ -140,10 +140,10 @@ Status ProtoStreamObjectSource::WriteMessage(const google::protobuf::Type& type,
                                              bool include_start_and_end,
                                              ObjectWriter* ow) const {
 
-  const TypeRenderer* type_renderer = FindTypeRenderer(type.name());
-  if (type_renderer != NULL) {
-    return (*type_renderer)(this, type, name, ow);
-  }
+    const TypeRenderer* type_renderer = FindTypeRenderer(type.name());
+    if (type_renderer != NULL) {
+      return (*type_renderer)(this, type, name, ow);
+    }
 
   const google::protobuf::Field* field = NULL;
   string field_name;
@@ -171,7 +171,9 @@ Status ProtoStreamObjectSource::WriteMessage(const google::protobuf::Type& type,
 
     if (field->cardinality() ==
         google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
-      if (IsMap(*field)) {
+      bool check_maps = true;
+
+      if (check_maps && IsMap(*field)) {
         ow->StartObject(field_name);
         ASSIGN_OR_RETURN(tag, RenderMap(field, field_name, tag, ow));
         ow->EndObject();
@@ -218,48 +220,32 @@ StatusOr<uint32> ProtoStreamObjectSource::RenderMap(
   const google::protobuf::Type* field_type =
       typeinfo_->GetTypeByTypeUrl(field->type_url());
   uint32 tag_to_return = 0;
-  if (IsPackable(*field) &&
-      list_tag ==
-          WireFormatLite::MakeTag(field->number(),
-                                  WireFormatLite::WIRETYPE_LENGTH_DELIMITED)) {
-    RETURN_IF_ERROR(RenderPackedMapEntry(field_type, ow));
-    tag_to_return = stream_->ReadTag();
-  } else {
-    do {
-      RETURN_IF_ERROR(RenderMapEntry(field_type, ow));
-    } while ((tag_to_return = stream_->ReadTag()) == list_tag);
-  }
-  return tag_to_return;
-}
-
-Status ProtoStreamObjectSource::RenderMapEntry(
-    const google::protobuf::Type* type, ObjectWriter* ow) const {
-  uint32 buffer32;
-  stream_->ReadVarint32(&buffer32);  // message length
-  int old_limit = stream_->PushLimit(buffer32);
-  string map_key;
-  for (uint32 tag = stream_->ReadTag(); tag != 0; tag = stream_->ReadTag()) {
-    const google::protobuf::Field* field = FindAndVerifyField(*type, tag);
-    if (field == NULL) {
-      WireFormat::SkipField(stream_, tag, NULL);
-      continue;
-    }
-    // Map field numbers are key = 1 and value = 2
-    if (field->number() == 1) {
-      map_key = ReadFieldValueAsString(*field);
-    } else if (field->number() == 2) {
-      if (map_key.empty()) {
-        return Status(util::error::INTERNAL, "Map key must be non-empty");
+  do {
+    // Render map entry message type.
+    uint32 buffer32;
+    stream_->ReadVarint32(&buffer32);  // message length
+    int old_limit = stream_->PushLimit(buffer32);
+    string map_key;
+    for (uint32 tag = stream_->ReadTag(); tag != 0; tag = stream_->ReadTag()) {
+      const google::protobuf::Field* field =
+          FindAndVerifyField(*field_type, tag);
+      if (field == NULL) {
+        WireFormat::SkipField(stream_, tag, NULL);
+        continue;
+      }
+      // Map field numbers are key = 1 and value = 2
+      if (field->number() == 1) {
+        map_key = ReadFieldValueAsString(*field);
+      } else if (field->number() == 2) {
+        if (map_key.empty()) {
+          return Status(util::error::INTERNAL, "Map key must be non-empty");
+        }
+        RETURN_IF_ERROR(RenderField(field, map_key, ow));
       }
-      // Disable case normalization for map keys as they are just data. We
-      // retain them intact.
-      ow->DisableCaseNormalizationForNextKey();
-      RETURN_IF_ERROR(RenderField(field, map_key, ow));
     }
-  }
-  stream_->PopLimit(old_limit);
-
-  return Status::OK;
+    stream_->PopLimit(old_limit);
+  } while ((tag_to_return = stream_->ReadTag()) == list_tag);
+  return tag_to_return;
 }
 
 Status ProtoStreamObjectSource::RenderPacked(
@@ -274,18 +260,6 @@ Status ProtoStreamObjectSource::RenderPacked(
   return Status::OK;
 }
 
-Status ProtoStreamObjectSource::RenderPackedMapEntry(
-    const google::protobuf::Type* type, ObjectWriter* ow) const {
-  uint32 length;
-  stream_->ReadVarint32(&length);
-  int old_limit = stream_->PushLimit(length);
-  while (stream_->BytesUntilLimit() > 0) {
-    RETURN_IF_ERROR(RenderMapEntry(type, ow));
-  }
-  stream_->PopLimit(old_limit);
-  return Status::OK;
-}
-
 Status ProtoStreamObjectSource::RenderTimestamp(
     const ProtoStreamObjectSource* os, const google::protobuf::Type& type,
     StringPiece field_name, ObjectWriter* ow) {
@@ -601,10 +575,10 @@ Status ProtoStreamObjectSource::RenderAny(const ProtoStreamObjectSource* os,
   // nested_type cannot be null at this time.
   const google::protobuf::Type* nested_type = resolved_type.ValueOrDie();
 
-  // We know the type so we can render it. Recursively parse the nested stream
-  // using a nested ProtoStreamObjectSource using our nested type information.
   google::protobuf::io::ArrayInputStream zero_copy_stream(value.data(), value.size());
   google::protobuf::io::CodedInputStream in_stream(&zero_copy_stream);
+  // We know the type so we can render it. Recursively parse the nested stream
+  // using a nested ProtoStreamObjectSource using our nested type information.
   ProtoStreamObjectSource nested_os(&in_stream, os->typeinfo_, *nested_type);
 
   // We manually call start and end object here so we can inject the @type.
@@ -676,8 +650,7 @@ void ProtoStreamObjectSource::InitRendererMap() {
       &ProtoStreamObjectSource::RenderString;
   (*renderers_)["google.protobuf.BytesValue"] =
       &ProtoStreamObjectSource::RenderBytes;
-  (*renderers_)["google.protobuf.Any"] =
-      &ProtoStreamObjectSource::RenderAny;
+  (*renderers_)["google.protobuf.Any"] = &ProtoStreamObjectSource::RenderAny;
   (*renderers_)["google.protobuf.Struct"] =
       &ProtoStreamObjectSource::RenderStruct;
   (*renderers_)["google.protobuf.Value"] =
@@ -704,87 +677,118 @@ ProtoStreamObjectSource::FindTypeRenderer(const string& type_url) {
 Status ProtoStreamObjectSource::RenderField(
     const google::protobuf::Field* field, StringPiece field_name,
     ObjectWriter* ow) const {
+  // Short-circuit message types as it tends to call WriteMessage recursively
+  // and ends up using a lot of stack space. Keep the stack usage of this
+  // message small in order to preserve stack space and not crash.
+  if (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
+    uint32 buffer32;
+    stream_->ReadVarint32(&buffer32);  // message length
+    int old_limit = stream_->PushLimit(buffer32);
+    // Get the nested message type for this field.
+    const google::protobuf::Type* type =
+        typeinfo_->GetTypeByTypeUrl(field->type_url());
+    if (type == NULL) {
+      return Status(util::error::INTERNAL,
+                    StrCat("Invalid configuration. Could not find the type: ",
+                           field->type_url()));
+    }
+
+    // Short-circuit any special type rendering to save call-stack space.
+    const TypeRenderer* type_renderer = FindTypeRenderer(type->name());
+
+    bool use_type_renderer = type_renderer != NULL;
+
+    if (use_type_renderer) {
+      RETURN_IF_ERROR((*type_renderer)(this, *type, field_name, ow));
+    } else {
+      RETURN_IF_ERROR(WriteMessage(*type, field_name, 0, true, ow));
+    }
+    if (!stream_->ConsumedEntireMessage()) {
+      return Status(util::error::INVALID_ARGUMENT,
+                    "Nested protocol message not parsed in its entirety.");
+    }
+    stream_->PopLimit(old_limit);
+  } else {
+    // Render all other non-message types.
+    return RenderNonMessageField(field, field_name, ow);
+  }
+  return Status::OK;
+}
+
+Status ProtoStreamObjectSource::RenderNonMessageField(
+    const google::protobuf::Field* field, StringPiece field_name,
+    ObjectWriter* ow) const {
+  // Temporary buffers of different types.
+  uint32 buffer32;
+  uint64 buffer64;
+  string strbuffer;
   switch (field->kind()) {
     case google::protobuf::Field_Kind_TYPE_BOOL: {
-      uint64 buffer64;
       stream_->ReadVarint64(&buffer64);
       ow->RenderBool(field_name, buffer64 != 0);
       break;
     }
     case google::protobuf::Field_Kind_TYPE_INT32: {
-      uint32 buffer32;
       stream_->ReadVarint32(&buffer32);
       ow->RenderInt32(field_name, bit_cast<int32>(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_INT64: {
-      uint64 buffer64;
       stream_->ReadVarint64(&buffer64);
       ow->RenderInt64(field_name, bit_cast<int64>(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_UINT32: {
-      uint32 buffer32;
       stream_->ReadVarint32(&buffer32);
       ow->RenderUint32(field_name, bit_cast<uint32>(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_UINT64: {
-      uint64 buffer64;
       stream_->ReadVarint64(&buffer64);
       ow->RenderUint64(field_name, bit_cast<uint64>(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_SINT32: {
-      uint32 buffer32;
       stream_->ReadVarint32(&buffer32);
       ow->RenderInt32(field_name, WireFormatLite::ZigZagDecode32(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_SINT64: {
-      uint64 buffer64;
       stream_->ReadVarint64(&buffer64);
       ow->RenderInt64(field_name, WireFormatLite::ZigZagDecode64(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_SFIXED32: {
-      uint32 buffer32;
       stream_->ReadLittleEndian32(&buffer32);
       ow->RenderInt32(field_name, bit_cast<int32>(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_SFIXED64: {
-      uint64 buffer64;
       stream_->ReadLittleEndian64(&buffer64);
       ow->RenderInt64(field_name, bit_cast<int64>(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_FIXED32: {
-      uint32 buffer32;
       stream_->ReadLittleEndian32(&buffer32);
       ow->RenderUint32(field_name, bit_cast<uint32>(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_FIXED64: {
-      uint64 buffer64;
       stream_->ReadLittleEndian64(&buffer64);
       ow->RenderUint64(field_name, bit_cast<uint64>(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_FLOAT: {
-      uint32 buffer32;
       stream_->ReadLittleEndian32(&buffer32);
       ow->RenderFloat(field_name, bit_cast<float>(buffer32));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_DOUBLE: {
-      uint64 buffer64;
       stream_->ReadLittleEndian64(&buffer64);
       ow->RenderDouble(field_name, bit_cast<double>(buffer64));
       break;
     }
     case google::protobuf::Field_Kind_TYPE_ENUM: {
-      uint32 buffer32;
       stream_->ReadVarint32(&buffer32);
 
       // If the field represents an explicit NULL value, render null.
@@ -811,40 +815,15 @@ Status ProtoStreamObjectSource::RenderField(
       break;
     }
     case google::protobuf::Field_Kind_TYPE_STRING: {
-      uint32 buffer32;
-      string str;
       stream_->ReadVarint32(&buffer32);  // string size.
-      stream_->ReadString(&str, buffer32);
-      ow->RenderString(field_name, str);
+      stream_->ReadString(&strbuffer, buffer32);
+      ow->RenderString(field_name, strbuffer);
       break;
     }
     case google::protobuf::Field_Kind_TYPE_BYTES: {
-      uint32 buffer32;
       stream_->ReadVarint32(&buffer32);  // bytes size.
-      string value;
-      stream_->ReadString(&value, buffer32);
-      ow->RenderBytes(field_name, value);
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_MESSAGE: {
-      uint32 buffer32;
-      stream_->ReadVarint32(&buffer32);  // message length
-      int old_limit = stream_->PushLimit(buffer32);
-      // Get the nested message type for this field.
-      const google::protobuf::Type* type =
-          typeinfo_->GetTypeByTypeUrl(field->type_url());
-      if (type == NULL) {
-        return Status(util::error::INTERNAL,
-                      StrCat("Invalid configuration. Could not find the type: ",
-                             field->type_url()));
-      }
-
-      RETURN_IF_ERROR(WriteMessage(*type, field_name, 0, true, ow));
-      if (!stream_->ConsumedEntireMessage()) {
-        return Status(util::error::INVALID_ARGUMENT,
-                      "Nested protocol message not parsed in its entirety.");
-      }
-      stream_->PopLimit(old_limit);
+      stream_->ReadString(&strbuffer, buffer32);
+      ow->RenderBytes(field_name, strbuffer);
       break;
     }
     default:
diff --git a/src/google/protobuf/util/internal/protostream_objectsource.h b/src/google/protobuf/util/internal/protostream_objectsource.h
index 3cd37aa1..78defa1d 100644
--- a/src/google/protobuf/util/internal/protostream_objectsource.h
+++ b/src/google/protobuf/util/internal/protostream_objectsource.h
@@ -122,20 +122,12 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectSource : public ObjectSource {
                                      StringPiece name, uint32 list_tag,
                                      ObjectWriter* ow) const;
 
-  // Renders an entry in a map, advancing stream pointers appropriately.
-  util::Status RenderMapEntry(const google::protobuf::Type* type,
-                                ObjectWriter* ow) const;
-
   // Renders a packed repeating field. A packed field is stored as:
   // {tag length item1 item2 item3} instead of the less efficient
   // {tag item1 tag item2 tag item3}.
   util::Status RenderPacked(const google::protobuf::Field* field,
                               ObjectWriter* ow) const;
 
-  // Equivalent of RenderPacked, but for map entries.
-  util::Status RenderPackedMapEntry(const google::protobuf::Type* type,
-                                      ObjectWriter* ow) const;
-
   // Renders a google.protobuf.Timestamp value to ObjectWriter
   static util::Status RenderTimestamp(const ProtoStreamObjectSource* os,
                                         const google::protobuf::Type& type,
@@ -210,6 +202,12 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectSource : public ObjectSource {
   util::Status RenderField(const google::protobuf::Field* field,
                              StringPiece field_name, ObjectWriter* ow) const;
 
+  // Same as above but renders all non-message field types. Callers don't call
+  // this function directly. They just use RenderField.
+  util::Status RenderNonMessageField(const google::protobuf::Field* field,
+                                       StringPiece field_name,
+                                       ObjectWriter* ow) const;
+
 
   // Reads field value according to Field spec in 'field' and returns the read
   // value as string. This only works for primitive datatypes (no message
@@ -238,6 +236,7 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectSource : public ObjectSource {
   // google::protobuf::Type of the message source.
   const google::protobuf::Type& type_;
 
+
   GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoStreamObjectSource);
 };
 
diff --git a/src/google/protobuf/util/internal/protostream_objectsource_test.cc b/src/google/protobuf/util/internal/protostream_objectsource_test.cc
index f6e5ee7a..561f6763 100644
--- a/src/google/protobuf/util/internal/protostream_objectsource_test.cc
+++ b/src/google/protobuf/util/internal/protostream_objectsource_test.cc
@@ -327,9 +327,16 @@ TEST_P(ProtostreamObjectSourceTest, RepeatingPrimitives) {
   DoTest(primitive, Primitive::descriptor());
 }
 
+TEST_P(ProtostreamObjectSourceTest, CustomJsonName) {
+  Author author;
+  author.set_id(12345);
+
+  ow_.StartObject("")->RenderUint64("@id", 12345)->EndObject();
+  DoTest(author, Author::descriptor());
+}
+
 TEST_P(ProtostreamObjectSourceTest, NestedMessage) {
   Author* author = new Author();
-  author->set_id(101L);
   author->set_name("Tolstoy");
   Book book;
   book.set_title("My Book");
@@ -338,7 +345,6 @@ TEST_P(ProtostreamObjectSourceTest, NestedMessage) {
   ow_.StartObject("")
       ->RenderString("title", "My Book")
       ->StartObject("author")
-      ->RenderUint64("id", bit_cast<uint64>(101LL))
       ->RenderString("name", "Tolstoy")
       ->EndObject()
       ->EndObject();
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter.cc b/src/google/protobuf/util/internal/protostream_objectwriter.cc
index 0958997c..786bf0be 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter.cc
+++ b/src/google/protobuf/util/internal/protostream_objectwriter.cc
@@ -51,7 +51,6 @@ namespace util {
 namespace converter {
 
 using google::protobuf::internal::WireFormatLite;
-using google::protobuf::io::CodedOutputStream;
 using util::error::INVALID_ARGUMENT;
 using util::Status;
 using util::StatusOr;
@@ -60,230 +59,31 @@ using util::StatusOr;
 ProtoStreamObjectWriter::ProtoStreamObjectWriter(
     TypeResolver* type_resolver, const google::protobuf::Type& type,
     strings::ByteSink* output, ErrorListener* listener)
-    : master_type_(type),
-      typeinfo_(TypeInfo::NewTypeInfo(type_resolver)),
-      own_typeinfo_(true),
-      done_(false),
-      element_(NULL),
-      size_insert_(),
-      output_(output),
-      buffer_(),
-      adapter_(&buffer_),
-      stream_(new CodedOutputStream(&adapter_)),
-      listener_(listener),
-      invalid_depth_(0),
-      tracker_(new ObjectLocationTracker()) {}
+    : ProtoWriter(type_resolver, type, output, listener),
+      master_type_(type),
+      current_(NULL) {}
 
 ProtoStreamObjectWriter::ProtoStreamObjectWriter(
     const TypeInfo* typeinfo, const google::protobuf::Type& type,
     strings::ByteSink* output, ErrorListener* listener)
-    : master_type_(type),
-      typeinfo_(typeinfo),
-      own_typeinfo_(false),
-      done_(false),
-      element_(NULL),
-      size_insert_(),
-      output_(output),
-      buffer_(),
-      adapter_(&buffer_),
-      stream_(new CodedOutputStream(&adapter_)),
-      listener_(listener),
-      invalid_depth_(0),
-      tracker_(new ObjectLocationTracker()) {}
+    : ProtoWriter(typeinfo, type, output, listener),
+      master_type_(type),
+      current_(NULL) {}
 
 ProtoStreamObjectWriter::~ProtoStreamObjectWriter() {
-  if (own_typeinfo_) {
-    delete typeinfo_;
-  }
-  if (element_ == NULL) return;
+  if (current_ == NULL) return;
   // Cleanup explicitly in order to avoid destructor stack overflow when input
   // is deeply nested.
   // Cast to BaseElement to avoid doing additional checks (like missing fields)
   // during pop().
   google::protobuf::scoped_ptr<BaseElement> element(
-      static_cast<BaseElement*>(element_.get())->pop<BaseElement>());
+      static_cast<BaseElement*>(current_.get())->pop<BaseElement>());
   while (element != NULL) {
     element.reset(element->pop<BaseElement>());
   }
 }
 
 namespace {
-
-// Writes an INT32 field, including tag to the stream.
-inline Status WriteInt32(int field_number, const DataPiece& data,
-                         CodedOutputStream* stream) {
-  StatusOr<int32> i32 = data.ToInt32();
-  if (i32.ok()) {
-    WireFormatLite::WriteInt32(field_number, i32.ValueOrDie(), stream);
-  }
-  return i32.status();
-}
-
-// writes an SFIXED32 field, including tag, to the stream.
-inline Status WriteSFixed32(int field_number, const DataPiece& data,
-                            CodedOutputStream* stream) {
-  StatusOr<int32> i32 = data.ToInt32();
-  if (i32.ok()) {
-    WireFormatLite::WriteSFixed32(field_number, i32.ValueOrDie(), stream);
-  }
-  return i32.status();
-}
-
-// Writes an SINT32 field, including tag, to the stream.
-inline Status WriteSInt32(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<int32> i32 = data.ToInt32();
-  if (i32.ok()) {
-    WireFormatLite::WriteSInt32(field_number, i32.ValueOrDie(), stream);
-  }
-  return i32.status();
-}
-
-// Writes a FIXED32 field, including tag, to the stream.
-inline Status WriteFixed32(int field_number, const DataPiece& data,
-                           CodedOutputStream* stream) {
-  StatusOr<uint32> u32 = data.ToUint32();
-  if (u32.ok()) {
-    WireFormatLite::WriteFixed32(field_number, u32.ValueOrDie(), stream);
-  }
-  return u32.status();
-}
-
-// Writes a UINT32 field, including tag, to the stream.
-inline Status WriteUInt32(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<uint32> u32 = data.ToUint32();
-  if (u32.ok()) {
-    WireFormatLite::WriteUInt32(field_number, u32.ValueOrDie(), stream);
-  }
-  return u32.status();
-}
-
-// Writes an INT64 field, including tag, to the stream.
-inline Status WriteInt64(int field_number, const DataPiece& data,
-                         CodedOutputStream* stream) {
-  StatusOr<int64> i64 = data.ToInt64();
-  if (i64.ok()) {
-    WireFormatLite::WriteInt64(field_number, i64.ValueOrDie(), stream);
-  }
-  return i64.status();
-}
-
-// Writes an SFIXED64 field, including tag, to the stream.
-inline Status WriteSFixed64(int field_number, const DataPiece& data,
-                            CodedOutputStream* stream) {
-  StatusOr<int64> i64 = data.ToInt64();
-  if (i64.ok()) {
-    WireFormatLite::WriteSFixed64(field_number, i64.ValueOrDie(), stream);
-  }
-  return i64.status();
-}
-
-// Writes an SINT64 field, including tag, to the stream.
-inline Status WriteSInt64(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<int64> i64 = data.ToInt64();
-  if (i64.ok()) {
-    WireFormatLite::WriteSInt64(field_number, i64.ValueOrDie(), stream);
-  }
-  return i64.status();
-}
-
-// Writes a FIXED64 field, including tag, to the stream.
-inline Status WriteFixed64(int field_number, const DataPiece& data,
-                           CodedOutputStream* stream) {
-  StatusOr<uint64> u64 = data.ToUint64();
-  if (u64.ok()) {
-    WireFormatLite::WriteFixed64(field_number, u64.ValueOrDie(), stream);
-  }
-  return u64.status();
-}
-
-// Writes a UINT64 field, including tag, to the stream.
-inline Status WriteUInt64(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<uint64> u64 = data.ToUint64();
-  if (u64.ok()) {
-    WireFormatLite::WriteUInt64(field_number, u64.ValueOrDie(), stream);
-  }
-  return u64.status();
-}
-
-// Writes a DOUBLE field, including tag, to the stream.
-inline Status WriteDouble(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<double> d = data.ToDouble();
-  if (d.ok()) {
-    WireFormatLite::WriteDouble(field_number, d.ValueOrDie(), stream);
-  }
-  return d.status();
-}
-
-// Writes a FLOAT field, including tag, to the stream.
-inline Status WriteFloat(int field_number, const DataPiece& data,
-                         CodedOutputStream* stream) {
-  StatusOr<float> f = data.ToFloat();
-  if (f.ok()) {
-    WireFormatLite::WriteFloat(field_number, f.ValueOrDie(), stream);
-  }
-  return f.status();
-}
-
-// Writes a BOOL field, including tag, to the stream.
-inline Status WriteBool(int field_number, const DataPiece& data,
-                        CodedOutputStream* stream) {
-  StatusOr<bool> b = data.ToBool();
-  if (b.ok()) {
-    WireFormatLite::WriteBool(field_number, b.ValueOrDie(), stream);
-  }
-  return b.status();
-}
-
-// Writes a BYTES field, including tag, to the stream.
-inline Status WriteBytes(int field_number, const DataPiece& data,
-                         CodedOutputStream* stream) {
-  StatusOr<string> c = data.ToBytes();
-  if (c.ok()) {
-    WireFormatLite::WriteBytes(field_number, c.ValueOrDie(), stream);
-  }
-  return c.status();
-}
-
-// Writes a STRING field, including tag, to the stream.
-inline Status WriteString(int field_number, const DataPiece& data,
-                          CodedOutputStream* stream) {
-  StatusOr<string> s = data.ToString();
-  if (s.ok()) {
-    WireFormatLite::WriteString(field_number, s.ValueOrDie(), stream);
-  }
-  return s.status();
-}
-
-// Writes an ENUM field, including tag, to the stream.
-inline Status WriteEnum(int field_number, const DataPiece& data,
-                        const google::protobuf::Enum* enum_type,
-                        CodedOutputStream* stream) {
-  StatusOr<int> e = data.ToEnum(enum_type);
-  if (e.ok()) {
-    WireFormatLite::WriteEnum(field_number, e.ValueOrDie(), stream);
-  }
-  return e.status();
-}
-
-// Given a google::protobuf::Type, returns the set of all required fields.
-std::set<const google::protobuf::Field*> GetRequiredFields(
-    const google::protobuf::Type& type) {
-  std::set<const google::protobuf::Field*> required;
-  for (int i = 0; i < type.fields_size(); i++) {
-    const google::protobuf::Field& field = type.fields(i);
-    if (field.cardinality() ==
-        google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
-      required.insert(&field);
-    }
-  }
-  return required;
-}
-
 // Utility method to split a string representation of Timestamp or Duration and
 // return the parts.
 void SplitSecondsAndNanos(StringPiece input, StringPiece* seconds,
@@ -298,6 +98,78 @@ void SplitSecondsAndNanos(StringPiece input, StringPiece* seconds,
   }
 }
 
+Status GetNanosFromStringPiece(StringPiece s_nanos,
+                               const char* parse_failure_message,
+                               const char* exceeded_limit_message,
+                               int32* nanos) {
+  *nanos = 0;
+
+  // Count the number of leading 0s and consume them.
+  int num_leading_zeros = 0;
+  while (s_nanos.Consume("0")) {
+    num_leading_zeros++;
+  }
+  int32 i_nanos = 0;
+  // 's_nanos' contains fractional seconds -- i.e. 'nanos' is equal to
+  // "0." + s_nanos.ToString() seconds. An int32 is used for the
+  // conversion to 'nanos', rather than a double, so that there is no
+  // loss of precision.
+  if (!s_nanos.empty() && !safe_strto32(s_nanos.ToString(), &i_nanos)) {
+    return Status(INVALID_ARGUMENT, parse_failure_message);
+  }
+  if (i_nanos > kNanosPerSecond || i_nanos < 0) {
+    return Status(INVALID_ARGUMENT, exceeded_limit_message);
+  }
+  // s_nanos should only have digits. No whitespace.
+  if (s_nanos.find_first_not_of("0123456789") != StringPiece::npos) {
+    return Status(INVALID_ARGUMENT, parse_failure_message);
+  }
+
+  if (i_nanos > 0) {
+    // 'scale' is the number of digits to the right of the decimal
+    // point in "0." + s_nanos.ToString()
+    int32 scale = num_leading_zeros + s_nanos.size();
+    // 'conversion' converts i_nanos into nanoseconds.
+    // conversion = kNanosPerSecond / static_cast<int32>(std::pow(10, scale))
+    // For efficiency, we precompute the conversion factor.
+    int32 conversion = 0;
+    switch (scale) {
+      case 1:
+        conversion = 100000000;
+        break;
+      case 2:
+        conversion = 10000000;
+        break;
+      case 3:
+        conversion = 1000000;
+        break;
+      case 4:
+        conversion = 100000;
+        break;
+      case 5:
+        conversion = 10000;
+        break;
+      case 6:
+        conversion = 1000;
+        break;
+      case 7:
+        conversion = 100;
+        break;
+      case 8:
+        conversion = 10;
+        break;
+      case 9:
+        conversion = 1;
+        break;
+      default:
+        return Status(INVALID_ARGUMENT, exceeded_limit_message);
+    }
+    *nanos = i_nanos * conversion;
+  }
+
+  return Status::OK;
+}
+
 }  // namespace
 
 ProtoStreamObjectWriter::AnyWriter::AnyWriter(ProtoStreamObjectWriter* parent)
@@ -421,7 +293,7 @@ void ProtoStreamObjectWriter::AnyWriter::StartAny(const DataPiece& value) {
   }
   // Resolve the type url, and report an error if we failed to resolve it.
   StatusOr<const google::protobuf::Type*> resolved_type =
-      parent_->typeinfo_->ResolveTypeUrl(type_url_);
+      parent_->typeinfo()->ResolveTypeUrl(type_url_);
   if (!resolved_type.ok()) {
     parent_->InvalidValue("Any", resolved_type.status().error_message());
     invalid_ = true;
@@ -440,8 +312,8 @@ void ProtoStreamObjectWriter::AnyWriter::StartAny(const DataPiece& value) {
 
   // Create our object writer and initialize it with the first StartObject
   // call.
-  ow_.reset(new ProtoStreamObjectWriter(parent_->typeinfo_, *type, &output_,
-                                        parent_->listener_));
+  ow_.reset(new ProtoStreamObjectWriter(parent_->typeinfo(), *type, &output_,
+                                        parent_->listener()));
   ow_->StartObject("");
 }
 
@@ -453,604 +325,431 @@ void ProtoStreamObjectWriter::AnyWriter::WriteAny() {
   }
   // Render the type_url and value fields directly to the stream.
   // type_url has tag 1 and value has tag 2.
-  WireFormatLite::WriteString(1, type_url_, parent_->stream_.get());
+  WireFormatLite::WriteString(1, type_url_, parent_->stream());
   if (!data_.empty()) {
-    WireFormatLite::WriteBytes(2, data_, parent_->stream_.get());
+    WireFormatLite::WriteBytes(2, data_, parent_->stream());
   }
 }
 
-ProtoStreamObjectWriter::ProtoElement::ProtoElement(
-    const TypeInfo* typeinfo, const google::protobuf::Type& type,
-    ProtoStreamObjectWriter* enclosing)
+ProtoStreamObjectWriter::Item::Item(ProtoStreamObjectWriter* enclosing,
+                                    ItemType item_type, bool is_placeholder,
+                                    bool is_list)
     : BaseElement(NULL),
       ow_(enclosing),
       any_(),
-      field_(NULL),
-      typeinfo_(typeinfo),
-      type_(type),
-      required_fields_(GetRequiredFields(type)),
-      is_repeated_type_(false),
-      size_index_(-1),
-      array_index_(-1),
-      element_type_(GetElementType(type_)) {
-  if (element_type_ == ANY) {
+      item_type_(item_type),
+      is_placeholder_(is_placeholder),
+      is_list_(is_list) {
+  if (item_type_ == ANY) {
     any_.reset(new AnyWriter(ow_));
   }
 }
 
-ProtoStreamObjectWriter::ProtoElement::ProtoElement(
-    ProtoStreamObjectWriter::ProtoElement* parent,
-    const google::protobuf::Field* field, const google::protobuf::Type& type,
-    ElementType element_type)
+ProtoStreamObjectWriter::Item::Item(ProtoStreamObjectWriter::Item* parent,
+                                    ItemType item_type, bool is_placeholder,
+                                    bool is_list)
     : BaseElement(parent),
       ow_(this->parent()->ow_),
       any_(),
-      field_(field),
-      typeinfo_(this->parent()->typeinfo_),
-      type_(type),
-      is_repeated_type_(element_type == ProtoElement::LIST ||
-                        element_type == ProtoElement::STRUCT_LIST ||
-                        element_type == ProtoElement::MAP ||
-                        element_type == ProtoElement::STRUCT_MAP),
-      size_index_(!is_repeated_type_ &&
-                          field->kind() ==
-                              google::protobuf::Field_Kind_TYPE_MESSAGE
-                      ? ow_->size_insert_.size()
-                      : -1),
-      array_index_(is_repeated_type_ ? 0 : -1),
-      element_type_(element_type) {
-  if (!is_repeated_type_) {
-    if (field->cardinality() ==
-        google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
-      // Update array_index_ if it is an explicit list.
-      if (this->parent()->array_index_ >= 0) this->parent()->array_index_++;
-    } else {
-      this->parent()->RegisterField(field);
-    }
-    if (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
-      required_fields_ = GetRequiredFields(type_);
-      int start_pos = ow_->stream_->ByteCount();
-      // length of serialized message is the final buffer position minus
-      // starting buffer position, plus length adjustments for size fields
-      // of any nested messages. We start with -start_pos here, so we only
-      // need to add the final buffer position to it at the end.
-      SizeInfo info = {start_pos, -start_pos};
-      ow_->size_insert_.push_back(info);
-    }
-  }
-  if (element_type == ANY) {
+      item_type_(item_type),
+      is_placeholder_(is_placeholder),
+      is_list_(is_list) {
+  if (item_type == ANY) {
     any_.reset(new AnyWriter(ow_));
   }
 }
 
-ProtoStreamObjectWriter::ProtoElement*
-ProtoStreamObjectWriter::ProtoElement::pop() {
-  // Calls the registered error listener for any required field(s) not yet
-  // seen.
-  for (set<const google::protobuf::Field*>::iterator it =
-           required_fields_.begin();
-       it != required_fields_.end(); ++it) {
-    ow_->MissingField((*it)->name());
-  }
-  // Computes the total number of proto bytes used by a message, also adjusts
-  // the size of all parent messages by the length of this size field.
-  // If size_index_ < 0, this is not a message, so no size field is added.
-  if (size_index_ >= 0) {
-    // Add the final buffer position to compute the total length of this
-    // serialized message. The stored value (before this addition) already
-    // contains the total length of the size fields of all nested messages
-    // minus the initial buffer position.
-    ow_->size_insert_[size_index_].size += ow_->stream_->ByteCount();
-    // Calculate the length required to serialize the size field of the
-    // message, and propagate this additional size information upward to
-    // all enclosing messages.
-    int size = ow_->size_insert_[size_index_].size;
-    int length = CodedOutputStream::VarintSize32(size);
-    for (ProtoElement* e = parent(); e != NULL; e = e->parent()) {
-      // Only nested messages have size field, lists do not have size field.
-      if (e->size_index_ >= 0) {
-        ow_->size_insert_[e->size_index_].size += length;
-      }
-    }
-  }
-  return BaseElement::pop<ProtoElement>();
-}
-
-void ProtoStreamObjectWriter::ProtoElement::RegisterField(
-    const google::protobuf::Field* field) {
-  if (!required_fields_.empty() &&
-      field->cardinality() ==
-          google::protobuf::Field_Cardinality_CARDINALITY_REQUIRED) {
-    required_fields_.erase(field);
-  }
-}
-
-string ProtoStreamObjectWriter::ProtoElement::ToString() const {
-  if (parent() == NULL) return "";
-  string loc = parent()->ToString();
-  if (field_->cardinality() !=
-          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED ||
-      parent()->field_ != field_) {
-    string name = field_->name();
-    int i = 0;
-    while (i < name.size() && (ascii_isalnum(name[i]) || name[i] == '_')) ++i;
-    if (i > 0 && i == name.size()) {  // safe field name
-      if (loc.empty()) {
-        loc = name;
-      } else {
-        StrAppend(&loc, ".", name);
-      }
-    } else {
-      StrAppend(&loc, "[\"", CEscape(name), "\"]");
-    }
-  }
-  if (field_->cardinality() ==
-          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED &&
-      array_index_ > 0) {
-    StrAppend(&loc, "[", array_index_ - 1, "]");
-  }
-  return loc.empty() ? "." : loc;
-}
-
-bool ProtoStreamObjectWriter::ProtoElement::OneofIndexTaken(int32 index) {
-  return ContainsKey(oneof_indices_, index);
-}
-
-void ProtoStreamObjectWriter::ProtoElement::TakeOneofIndex(int32 index) {
-  InsertIfNotPresent(&oneof_indices_, index);
-}
-
-bool ProtoStreamObjectWriter::ProtoElement::InsertMapKeyIfNotPresent(
+bool ProtoStreamObjectWriter::Item::InsertMapKeyIfNotPresent(
     StringPiece map_key) {
   return InsertIfNotPresent(&map_keys_, map_key.ToString());
 }
 
-inline void ProtoStreamObjectWriter::InvalidName(StringPiece unknown_name,
-                                                 StringPiece message) {
-  listener_->InvalidName(location(), ToSnakeCase(unknown_name), message);
-}
-
-inline void ProtoStreamObjectWriter::InvalidValue(StringPiece type_name,
-                                                  StringPiece value) {
-  listener_->InvalidValue(location(), type_name, value);
-}
-
-inline void ProtoStreamObjectWriter::MissingField(StringPiece missing_name) {
-  listener_->MissingField(location(), missing_name);
-}
-
 ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartObject(
     StringPiece name) {
-  // Starting the root message. Create the root ProtoElement and return.
-  if (element_ == NULL) {
-    if (!name.empty()) {
-      InvalidName(name, "Root element should not be named.");
-    }
-    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
+  if (invalid_depth() > 0) {
+    IncrementInvalidDepth();
+    return this;
+  }
+
+  // Starting the root message. Create the root Item and return.
+  // ANY message type does not need special handling, just set the ItemType
+  // to ANY.
+  if (current_ == NULL) {
+    ProtoWriter::StartObject(name);
+    current_.reset(new Item(
+        this, master_type_.name() == kAnyType ? Item::ANY : Item::MESSAGE,
+        false, false));
 
     // If master type is a special type that needs extra values to be written to
     // stream, we write those values.
     if (master_type_.name() == kStructType) {
-      StartStruct(NULL);
-    } else if (master_type_.name() == kStructValueType) {
-      // We got a StartObject call with google.protobuf.Value field. This means
-      // we are starting an object within google.protobuf.Value type. The only
-      // object within that type is a struct type. So start a struct.
-      const google::protobuf::Field* field = StartStructValueInStruct(NULL);
-      StartStruct(field);
+      // Struct has a map<string, Value> field called "fields".
+      // https://github.com/google/protobuf/blob/master/src/google/protobuf/struct.proto
+      // "fields": [
+      Push("fields", Item::MAP, true, true);
+      return this;
     }
-    return this;
-  }
 
-  const google::protobuf::Field* field = NULL;
-  if (element_ != NULL && element_->IsAny()) {
-    element_->any()->StartObject(name);
-    return this;
-  } else if (element_ != NULL &&
-             (element_->IsMap() || element_->IsStructMap())) {
-    if (!ValidMapKey(name)) {
-      ++invalid_depth_;
+    if (master_type_.name() == kStructValueType) {
+      // We got a StartObject call with google.protobuf.Value field. The only
+      // object within that type is a struct type. So start a struct.
+      //
+      // The struct field in Value type is named "struct_value"
+      // https://github.com/google/protobuf/blob/master/src/google/protobuf/struct.proto
+      // Also start the map field "fields" within the struct.
+      // "struct_value": {
+      //   "fields": [
+      Push("struct_value", Item::MESSAGE, true, false);
+      Push("fields", Item::MAP, true, true);
       return this;
     }
 
-    field = StartMapEntry(name);
-    if (element_->IsStructMapEntry()) {
-      // If the top element is a map entry, this means we are starting another
-      // struct within a struct.
-      field = StartStructValueInStruct(field);
+    if (master_type_.name() == kStructListValueType) {
+      InvalidValue(kStructListValueType,
+                   "Cannot start root message with ListValue.");
     }
-  } else if (element_ != NULL && element_->IsStructList()) {
-    // If the top element is a list, then we are starting a list field within a
-    // struct.
-    field = Lookup(name);
-    field = StartStructValueInStruct(field);
-  } else {
-    field = BeginNamed(name, false);
-  }
-  if (field == NULL) {
-    return this;
-  }
 
-  const google::protobuf::Type* type = LookupType(field);
-  if (type == NULL) {
-    ++invalid_depth_;
-    InvalidName(name,
-                StrCat("Missing descriptor for field: ", field->type_url()));
     return this;
   }
 
-  // Check to see if this field is a oneof and that no oneof in that group has
-  // already been set.
-  if (!ValidOneof(*field, name)) {
-    ++invalid_depth_;
+  // Send all ANY events to AnyWriter.
+  if (current_->IsAny()) {
+    current_->any()->StartObject(name);
     return this;
   }
 
-  if (field->type_url() == GetFullTypeWithUrl(kStructType)) {
-    // Start a struct object.
-    StartStruct(field);
-  } else if (field->type_url() == GetFullTypeWithUrl(kStructValueType)) {
-    // We got a StartObject call with google.protobuf.Value field. This means we
-    // are starting an object within google.protobuf.Value type. The only object
-    // within that type is a struct type. So start a struct.
-    field = StartStructValueInStruct(field);
-    StartStruct(field);
-  } else if (field->type_url() == GetFullTypeWithUrl(kAnyType)) {
-    // Begin an Any. We can't do the real work till we get the @type field.
-    WriteTag(*field);
-    element_.reset(
-        new ProtoElement(element_.release(), field, *type, ProtoElement::ANY));
-  } else if (IsMap(*field)) {
-    // Begin a map.
-    // A map is triggered by a StartObject() call if the current field has a map
-    // type. Map values are written to proto in a manner detailed in comments
-    // above StartMapEntry() function.
-    element_.reset(
-        new ProtoElement(element_.release(), field, *type, ProtoElement::MAP));
-  } else {
-      WriteTag(*field);
-    element_.reset(new ProtoElement(element_.release(), field, *type,
-                                    ProtoElement::MESSAGE));
-  }
-  return this;
-}
-
-// Proto3 maps are represented on the wire as a message with
-// "key" and a "value".
-//
-// For example, the syntax:
-// map<key_type, value_type> map_field = N;
-//
-// is represented as:
-// message MapFieldEntry {
-//   option map_entry = true;   // marks the map construct in the descriptor
-//
-//   key_type key = 1;
-//   value_type value = 2;
-// }
-// repeated MapFieldEntry map_field = N;
-//
-// See go/proto3-maps for more information.
-const google::protobuf::Field* ProtoStreamObjectWriter::StartMapEntry(
-    StringPiece name) {
-  // top of stack is already a map field
-  const google::protobuf::Field* field = element_->field();
-  const google::protobuf::Type& type = element_->type();
-  // If we come from a regular map, use MAP_ENTRY or if we come from a struct,
-  // use STRUCT_MAP_ENTRY. These values are used later in StartObject/StartList
-  // or RenderDataPiece for making appropriate decisions.
-  ProtoElement::ElementType element_type = element_->IsStructMap()
-                                               ? ProtoElement::STRUCT_MAP_ENTRY
-                                               : ProtoElement::MAP_ENTRY;
-  WriteTag(*field);
-  element_.reset(
-      new ProtoElement(element_.release(), field, type, element_type));
-  RenderDataPiece("key", DataPiece(name));
-  return BeginNamed("value", false);
-}
+  // If we are within a map, we render name as keys and send StartObject to the
+  // value field.
+  if (current_->IsMap()) {
+    if (!ValidMapKey(name)) {
+      IncrementInvalidDepth();
+      return this;
+    }
 
-// Starts a google.protobuf.Struct.
-// 'field' represents a field in a message of type google.protobuf.Struct.  A
-// struct contains a map with name 'fields'. This function starts this map as
-// well.
-// When 'field' is NULL, it means that the top level message is of struct
-// type.
-void ProtoStreamObjectWriter::StartStruct(
-    const google::protobuf::Field* field) {
-  const google::protobuf::Type* type = NULL;
-  if (field) {
-    type = LookupType(field);
-    WriteTag(*field);
-    element_.reset(new ProtoElement(element_.release(), field, *type,
-                                    ProtoElement::STRUCT));
-  }
-  const google::protobuf::Field* struct_field = BeginNamed("fields", false);
+    // Map is a repeated field of message type with a "key" and a "value" field.
+    // https://developers.google.com/protocol-buffers/docs/proto3?hl=en#maps
+    // message MapFieldEntry {
+    //   key_type key = 1;
+    //   value_type value = 2;
+    // }
+    //
+    // repeated MapFieldEntry map_field = N;
+    //
+    // That means, we render the following element within a list (hence no
+    // name):
+    // { "key": "<name>", "value": {
+    Push("", Item::MESSAGE, false, false);
+    ProtoWriter::RenderDataPiece("key", DataPiece(name));
+    Push("value", Item::MESSAGE, true, false);
+
+    // Make sure we are valid so far after starting map fields.
+    if (invalid_depth() > 0) return this;
+
+    // If top of stack is g.p.Struct type, start the struct the map field within
+    // it.
+    if (element() != NULL && IsStruct(*element()->parent_field())) {
+      // Render "fields": [
+      Push("fields", Item::MAP, true, true);
+      return this;
+    }
 
-  if (!struct_field) {
-    // It is a programmatic error if this happens. Log an error.
-    GOOGLE_LOG(ERROR) << "Invalid internal state. Cannot find 'fields' within "
-               << (field ? field->type_url() : "google.protobuf.Struct");
-    return;
+    // If top of stack is g.p.Value type, start the Struct within it.
+    if (element() != NULL && IsStructValue(*element()->parent_field())) {
+      // Render
+      // "struct_value": {
+      //   "fields": [
+      Push("struct_value", Item::MESSAGE, true, false);
+      Push("fields", Item::MAP, true, true);
+    }
+    return this;
   }
 
-  type = LookupType(struct_field);
-  element_.reset(new ProtoElement(element_.release(), struct_field, *type,
-                                  ProtoElement::STRUCT_MAP));
-}
+  const google::protobuf::Field* field = BeginNamed(name, false);
+  if (field == NULL) return this;
 
-// Starts a "struct_value" within struct.proto's google.protobuf.Value type.
-// 'field' should be of the type google.protobuf.Value.
-// Returns the field identifying "struct_value" within the given field.
-//
-// If field is NULL, then we are starting struct_value at the top-level, in
-// this case skip writing any tag information for the passed field.
-const google::protobuf::Field*
-ProtoStreamObjectWriter::StartStructValueInStruct(
-    const google::protobuf::Field* field) {
-  if (field) {
-    const google::protobuf::Type* type = LookupType(field);
-    WriteTag(*field);
-    element_.reset(new ProtoElement(element_.release(), field, *type,
-                                    ProtoElement::STRUCT_VALUE));
-  }
-  return BeginNamed("struct_value", false);
-}
-
-// Starts a "list_value" within struct.proto's google.protobuf.Value type.
-// 'field' should be of the type google.protobuf.Value.
-// Returns the field identifying "list_value" within the given field.
-//
-// If field is NULL, then we are starting list_value at the top-level, in
-// this case skip writing any tag information for the passed field.
-const google::protobuf::Field* ProtoStreamObjectWriter::StartListValueInStruct(
-    const google::protobuf::Field* field) {
-  if (field) {
-    const google::protobuf::Type* type = LookupType(field);
-    WriteTag(*field);
-    element_.reset(new ProtoElement(element_.release(), field, *type,
-                                    ProtoElement::STRUCT_VALUE));
+  if (IsStruct(*field)) {
+    // Start a struct object.
+    // Render
+    // "<name>": {
+    //   "fields": {
+    Push(name, Item::MESSAGE, false, false);
+    Push("fields", Item::MAP, true, true);
+    return this;
   }
-  const google::protobuf::Field* list_value = BeginNamed("list_value", false);
 
-  if (!list_value) {
-    // It is a programmatic error if this happens. Log an error.
-    GOOGLE_LOG(ERROR) << "Invalid internal state. Cannot find 'list_value' within "
-               << (field ? field->type_url() : "google.protobuf.Value");
-    return field;
+  if (IsStructValue(*field)) {
+    // We got a StartObject call with google.protobuf.Value field.  The only
+    // object within that type is a struct type. So start a struct.
+    // Render
+    // "<name>": {
+    //   "struct_value": {
+    //     "fields": {
+    Push(name, Item::MESSAGE, false, false);
+    Push("struct_value", Item::MESSAGE, true, false);
+    Push("fields", Item::MAP, true, true);
+    return this;
   }
 
-  return StartRepeatedValuesInListValue(list_value);
-}
-
-// Starts the repeated "values" field in struct.proto's
-// google.protobuf.ListValue type. 'field' should be of type
-// google.protobuf.ListValue.
-//
-// If field is NULL, then we are starting ListValue at the top-level, in
-// this case skip writing any tag information for the passed field.
-const google::protobuf::Field*
-ProtoStreamObjectWriter::StartRepeatedValuesInListValue(
-    const google::protobuf::Field* field) {
-  if (field) {
-    const google::protobuf::Type* type = LookupType(field);
-    WriteTag(*field);
-    element_.reset(new ProtoElement(element_.release(), field, *type,
-                                    ProtoElement::STRUCT_LIST_VALUE));
+  if (IsMap(*field)) {
+    // Begin a map. A map is triggered by a StartObject() call if the current
+    // field has a map type.
+    // A map type is always repeated, hence set is_list to true.
+    // Render
+    // "<name>": [
+    Push(name, Item::MAP, false, true);
+    return this;
   }
-  return BeginNamed("values", true);
-}
 
-void ProtoStreamObjectWriter::SkipElements() {
-  if (element_ == NULL) return;
-
-  ProtoElement::ElementType element_type = element_->element_type();
-  while (element_type == ProtoElement::STRUCT ||
-         element_type == ProtoElement::STRUCT_LIST_VALUE ||
-         element_type == ProtoElement::STRUCT_VALUE ||
-         element_type == ProtoElement::STRUCT_MAP_ENTRY ||
-         element_type == ProtoElement::MAP_ENTRY) {
-    element_.reset(element_->pop());
-    element_type =
-        element_ != NULL ? element_->element_type() : ProtoElement::MESSAGE;
-  }
+  // A regular message type. Pass it directly to ProtoWriter.
+  // Render
+  // "<name>": {
+  Push(name, IsAny(*field) ? Item::ANY : Item::MESSAGE, false, false);
+  return this;
 }
 
 ProtoStreamObjectWriter* ProtoStreamObjectWriter::EndObject() {
-  if (invalid_depth_ > 0) {
-    --invalid_depth_;
+  if (invalid_depth() > 0) {
+    DecrementInvalidDepth();
     return this;
   }
-  if (element_ != NULL && element_->IsAny()) {
-    if (element_->any()->EndObject()) {
-      return this;
-    }
-  }
-  if (element_ != NULL) {
-    element_.reset(element_->pop());
-  }
 
-  // Skip sentinel elements added to keep track of new proto3 types - map,
-  // struct.
-  SkipElements();
+  if (current_ == NULL) return this;
 
-
-  // If ending the root element,
-  // then serialize the full message with calculated sizes.
-  if (element_ == NULL) {
-    WriteRootMessage();
+  if (current_->IsAny()) {
+    if (current_->any()->EndObject()) return this;
   }
+
+  Pop();
+
   return this;
 }
 
 ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartList(StringPiece name) {
-  const google::protobuf::Field* field = NULL;
+  if (invalid_depth() > 0) {
+    IncrementInvalidDepth();
+    return this;
+  }
+
   // Since we cannot have a top-level repeated item in protobuf, the only way
-  // element_ can be null when here is when we start a top-level list
-  // google.protobuf.ListValue.
-  if (element_ == NULL) {
+  // this is valid is if we start a special type google.protobuf.ListValue or
+  // google.protobuf.Value.
+  if (current_ == NULL) {
     if (!name.empty()) {
       InvalidName(name, "Root element should not be named.");
+      IncrementInvalidDepth();
+      return this;
     }
-    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
 
     // If master type is a special type that needs extra values to be written to
     // stream, we write those values.
     if (master_type_.name() == kStructValueType) {
       // We got a StartList with google.protobuf.Value master type. This means
       // we have to start the "list_value" within google.protobuf.Value.
-      field = StartListValueInStruct(NULL);
-    } else if (master_type_.name() == kStructListValueType) {
+      //
+      // See
+      // https://github.com/google/protobuf/blob/master/src/google/protobuf/struct.proto
+      //
+      // Render
+      // "<name>": {
+      //   "list_value": {
+      //     "values": [  // Start this list.
+      ProtoWriter::StartObject(name);
+      current_.reset(new Item(this, Item::MESSAGE, false, false));
+      Push("list_value", Item::MESSAGE, true, false);
+      Push("values", Item::MESSAGE, true, true);
+      return this;
+    }
+
+    if (master_type_.name() == kStructListValueType) {
       // We got a StartList with google.protobuf.ListValue master type. This
       // means we have to start the "values" within google.protobuf.ListValue.
-      field = StartRepeatedValuesInListValue(NULL);
+      //
+      // Render
+      // "<name>": {
+      //   "values": [  // Start this list.
+      ProtoWriter::StartObject(name);
+      current_.reset(new Item(this, Item::MESSAGE, false, false));
+      Push("values", Item::MESSAGE, true, true);
+      return this;
     }
 
-    // field is NULL when master_type_ is anything other than
-    // google.protobuf.Value or google.protobuf.ListValue.
-    if (field) {
-      const google::protobuf::Type* type = LookupType(field);
-      element_.reset(new ProtoElement(element_.release(), field, *type,
-                                      ProtoElement::STRUCT_LIST));
-    }
+    // Send the event to ProtoWriter so proper errors can be reported.
+    //
+    // Render a regular list:
+    // "<name>": [
+    ProtoWriter::StartList(name);
+    current_.reset(new Item(this, Item::MESSAGE, false, true));
     return this;
   }
 
-  if (element_->IsAny()) {
-    element_->any()->StartList(name);
+  if (current_->IsAny()) {
+    current_->any()->StartList(name);
     return this;
   }
-  // The type of element we push to stack.
-  ProtoElement::ElementType element_type = ProtoElement::LIST;
 
-  // Check if we need to start a map. This can heppen when there is either a map
-  // or a struct type within a list.
-  if (element_->IsMap() || element_->IsStructMap()) {
+  // If the top of stack is a map, we are starting a list value within a map.
+  // Since map does not allow repeated values, this can only happen when the map
+  // value is of a special type that renders a list in JSON.  These can be one
+  // of 3 cases:
+  // i. We are rendering a list value within google.protobuf.Struct
+  // ii. We are rendering a list value within google.protobuf.Value
+  // iii. We are rendering a list value with type google.protobuf.ListValue.
+  if (current_->IsMap()) {
     if (!ValidMapKey(name)) {
-      ++invalid_depth_;
+      IncrementInvalidDepth();
       return this;
     }
 
-    field = StartMapEntry(name);
-    if (field == NULL) return this;
+    // Start the repeated map entry object.
+    // Render
+    // { "key": "<name>", "value": {
+    Push("", Item::MESSAGE, false, false);
+    ProtoWriter::RenderDataPiece("key", DataPiece(name));
+    Push("value", Item::MESSAGE, true, false);
+
+    // Make sure we are valid after pushing all above items.
+    if (invalid_depth() > 0) return this;
+
+    // case i and ii above. Start "list_value" field within g.p.Value
+    if (element() != NULL && element()->parent_field() != NULL) {
+      // Render
+      // "list_value": {
+      //   "values": [  // Start this list
+      if (IsStructValue(*element()->parent_field())) {
+        Push("list_value", Item::MESSAGE, true, false);
+        Push("values", Item::MESSAGE, true, true);
+        return this;
+      }
 
-    if (element_->IsStructMapEntry()) {
-      // If the top element is a map entry, this means we are starting a list
-      // within a struct or a map.
-      // An example sequence of calls would be
-      //    StartObject -> StartList
-      field = StartListValueInStruct(field);
-      if (field == NULL) return this;
+      // Render
+      // "values": [
+      if (IsStructListValue(*element()->parent_field())) {
+        // case iii above. Bind directly to g.p.ListValue
+        Push("values", Item::MESSAGE, true, true);
+        return this;
+      }
     }
 
-    element_type = ProtoElement::STRUCT_LIST;
-  } else if (element_->IsStructList()) {
-    // If the top element is a STRUCT_LIST, this means we are starting a list
-    // within the current list (inside a struct).
-    // An example call sequence would be
-    //    StartObject -> StartList -> StartList
-    // with StartObject starting a struct.
+    // Report an error.
+    InvalidValue("Map", StrCat("Cannot have repeated items ('", name,
+                               "') within a map."));
+    return this;
+  }
 
-    // Lookup the last list type in element stack as we are adding an element of
-    // the same type.
-    field = Lookup(name);
-    if (field == NULL) return this;
+  // When name is empty and stack is not empty, we are rendering an item within
+  // a list.
+  if (name.empty()) {
+    if (element() != NULL && element()->parent_field() != NULL) {
+      if (IsStructValue(*element()->parent_field())) {
+        // Since it is g.p.Value, we bind directly to the list_value.
+        // Render
+        // {  // g.p.Value item within the list
+        //   "list_value": {
+        //     "values": [
+        Push("", Item::MESSAGE, false, false);
+        Push("list_value", Item::MESSAGE, true, false);
+        Push("values", Item::MESSAGE, true, true);
+        return this;
+      }
 
-    field = StartListValueInStruct(field);
-    if (field == NULL) return this;
+      if (IsStructListValue(*element()->parent_field())) {
+        // Since it is g.p.ListValue, we bind to it directly.
+        // Render
+        // {  // g.p.ListValue item within the list
+        //   "values": [
+        Push("", Item::MESSAGE, false, false);
+        Push("values", Item::MESSAGE, true, true);
+        return this;
+      }
+    }
 
-    element_type = ProtoElement::STRUCT_LIST;
-  } else {
-    // Lookup field corresponding to 'name'. If it is a google.protobuf.Value
-    // or google.protobuf.ListValue type, then StartList is a valid call, start
-    // this list.
-    // We cannot use Lookup() here as it will produce InvalidName() error if the
-    // field is not found. We do not want to error here as it would cause us to
-    // report errors twice, once here and again later in BeginNamed() call.
-    // Also we ignore if the field is not found here as it is caught later.
-    field = typeinfo_->FindField(&element_->type(), name);
-
-    // Only check for oneof collisions on the first StartList call. We identify
-    // the first call with !name.empty() check. Subsequent list element calls
-    // will not have the name filled.
-    if (!name.empty() && field && !ValidOneof(*field, name)) {
-      ++invalid_depth_;
+    // Pass the event to underlying ProtoWriter.
+    Push(name, Item::MESSAGE, false, true);
+    return this;
+  }
+
+  // name is not empty
+  const google::protobuf::Field* field = Lookup(name);
+  if (field == NULL) {
+    IncrementInvalidDepth();
+    return this;
+  }
+
+  if (IsStructValue(*field)) {
+    // If g.p.Value is repeated, start that list. Otherwise, start the
+    // "list_value" within it.
+    if (IsRepeated(*field)) {
+      // Render it just like a regular repeated field.
+      // "<name>": [
+      Push(name, Item::MESSAGE, false, true);
       return this;
     }
 
-    // It is an error to try to bind to map, which behind the scenes is a list.
-    if (field && IsMap(*field)) {
-      // Push field to stack for error location tracking & reporting.
-      element_.reset(new ProtoElement(element_.release(), field,
-                                      *LookupType(field),
-                                      ProtoElement::MESSAGE));
-      InvalidValue("Map", "Cannot bind a list to map.");
-      ++invalid_depth_;
-      element_.reset(element_->pop());
+    // Start the "list_value" field.
+    // Render
+    // "<name>": {
+    //   "list_value": {
+    //     "values": [
+    Push(name, Item::MESSAGE, false, false);
+    Push("list_value", Item::MESSAGE, true, false);
+    Push("values", Item::MESSAGE, true, true);
+    return this;
+  }
+
+  if (IsStructListValue(*field)) {
+    // If g.p.ListValue is repeated, start that list. Otherwise, start the
+    // "values" within it.
+    if (IsRepeated(*field)) {
+      // Render it just like a regular repeated field.
+      // "<name>": [
+      Push(name, Item::MESSAGE, false, true);
       return this;
     }
 
-    if (field && field->type_url() == GetFullTypeWithUrl(kStructValueType)) {
-      // There are 2 cases possible:
-      //   a. g.p.Value is repeated
-      //   b. g.p.Value is not repeated
-      //
-      // For case (a), the StartList should bind to the repeated g.p.Value.
-      // For case (b), the StartList should bind to g.p.ListValue within the
-      // g.p.Value.
-      //
-      // This means, for case (a), we treat it just like any other repeated
-      // message, except we would apply an appropriate element_type so future
-      // Start or Render calls are routed appropriately.
-      if (field->cardinality() !=
-          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
-        field = StartListValueInStruct(field);
-      }
-      element_type = ProtoElement::STRUCT_LIST;
-    } else if (field &&
-               field->type_url() == GetFullTypeWithUrl(kStructListValueType)) {
-      // We got a StartList with google.protobuf.ListValue master type. This
-      // means we have to start the "values" within google.protobuf.ListValue.
-      field = StartRepeatedValuesInListValue(field);
-    } else {
-      // If no special types are to be bound, fall back to normal processing of
-      // StartList.
-      field = BeginNamed(name, true);
-    }
-    if (field == NULL) return this;
+    // Start the "values" field within g.p.ListValue.
+    // Render
+    // "<name>": {
+    //   "values": [
+    Push(name, Item::MESSAGE, false, false);
+    Push("values", Item::MESSAGE, true, true);
+    return this;
   }
 
-  const google::protobuf::Type* type = LookupType(field);
-  if (type == NULL) {
-    ++invalid_depth_;
-    InvalidName(name,
-                StrCat("Missing descriptor for field: ", field->type_url()));
+  // If we are here, the field should be repeated. Report an error otherwise.
+  if (!IsRepeated(*field)) {
+    IncrementInvalidDepth();
+    InvalidName(name, "Proto field is not repeating, cannot start list.");
     return this;
   }
 
-  element_.reset(
-      new ProtoElement(element_.release(), field, *type, element_type));
+  if (IsMap(*field)) {
+    InvalidValue("Map",
+                 StrCat("Cannot bind a list to map for field '", name, "'."));
+    IncrementInvalidDepth();
+    return this;
+  }
+
+  // Pass the event to ProtoWriter.
+  // Render
+  // "<name>": [
+  Push(name, Item::MESSAGE, false, true);
   return this;
 }
 
 ProtoStreamObjectWriter* ProtoStreamObjectWriter::EndList() {
-  if (invalid_depth_ > 0) {
-    --invalid_depth_;
-  } else if (element_ != NULL) {
-    if (element_->IsAny()) {
-      element_->any()->EndList();
-    } else {
-      element_.reset(element_->pop());
-      // Skip sentinel elements added to keep track of new proto3 types - map,
-      // struct.
-      SkipElements();
-    }
+  if (invalid_depth() > 0) {
+    DecrementInvalidDepth();
+    return this;
   }
 
-  // When element_ is NULL, we have reached the root message type. Write out
-  // the bytes.
-  if (element_ == NULL) {
-    WriteRootMessage();
+  if (current_ == NULL) return this;
+
+  if (current_->IsAny()) {
+    current_->any()->EndList();
+    return this;
   }
+
+  Pop();
   return this;
 }
 
@@ -1083,7 +782,7 @@ Status ProtoStreamObjectWriter::RenderStructValue(ProtoStreamObjectWriter* ow,
                     "null values are supported.");
     }
   }
-  ow->RenderDataPiece(struct_field_name, data);
+  ow->ProtoWriter::RenderDataPiece(struct_field_name, data);
   return Status::OK;
 }
 
@@ -1105,15 +804,15 @@ Status ProtoStreamObjectWriter::RenderTimestamp(ProtoStreamObjectWriter* ow,
   }
 
 
-  ow->RenderDataPiece("seconds", DataPiece(seconds));
-  ow->RenderDataPiece("nanos", DataPiece(nanos));
+  ow->ProtoWriter::RenderDataPiece("seconds", DataPiece(seconds));
+  ow->ProtoWriter::RenderDataPiece("nanos", DataPiece(nanos));
   return Status::OK;
 }
 
 static inline util::Status RenderOneFieldPath(ProtoStreamObjectWriter* ow,
                                                 StringPiece path) {
-  ow->RenderDataPiece("paths",
-                      DataPiece(ConvertFieldMaskPath(path, &ToSnakeCase)));
+  ow->ProtoWriter::RenderDataPiece(
+      "paths", DataPiece(ConvertFieldMaskPath(path, &ToSnakeCase)));
   return Status::OK;
 }
 
@@ -1162,224 +861,133 @@ Status ProtoStreamObjectWriter::RenderDuration(ProtoStreamObjectWriter* ow,
                   "Invalid duration format, failed to parse seconds");
   }
 
-  double d_nanos = 0;
-  if (!safe_strtod("0." + s_nanos.ToString(), &d_nanos)) {
-    return Status(INVALID_ARGUMENT,
-                  "Invalid duration format, failed to parse nanos seconds");
+  int32 nanos = 0;
+  Status nanos_status = GetNanosFromStringPiece(
+      s_nanos, "Invalid duration format, failed to parse nano seconds",
+      "Duration value exceeds limits", &nanos);
+  if (!nanos_status.ok()) {
+    return nanos_status;
   }
+  nanos = sign * nanos;
 
-  int32 nanos = sign * static_cast<int32>(d_nanos * kNanosPerSecond);
   int64 seconds = sign * unsigned_seconds;
-
   if (seconds > kMaxSeconds || seconds < kMinSeconds ||
       nanos <= -kNanosPerSecond || nanos >= kNanosPerSecond) {
     return Status(INVALID_ARGUMENT, "Duration value exceeds limits");
   }
 
-  ow->RenderDataPiece("seconds", DataPiece(seconds));
-  ow->RenderDataPiece("nanos", DataPiece(nanos));
+  ow->ProtoWriter::RenderDataPiece("seconds", DataPiece(seconds));
+  ow->ProtoWriter::RenderDataPiece("nanos", DataPiece(nanos));
   return Status::OK;
 }
 
 Status ProtoStreamObjectWriter::RenderWrapperType(ProtoStreamObjectWriter* ow,
                                                   const DataPiece& data) {
-  ow->RenderDataPiece("value", data);
+  ow->ProtoWriter::RenderDataPiece("value", data);
   return Status::OK;
 }
 
 ProtoStreamObjectWriter* ProtoStreamObjectWriter::RenderDataPiece(
     StringPiece name, const DataPiece& data) {
   Status status;
-  if (invalid_depth_ > 0) return this;
-  if (element_ != NULL && element_->IsAny()) {
-    element_->any()->RenderDataPiece(name, data);
+  if (invalid_depth() > 0) return this;
+
+  if (current_ == NULL) {
+    const TypeRenderer* type_renderer =
+        FindTypeRenderer(GetFullTypeWithUrl(master_type_.name()));
+    if (type_renderer == NULL) {
+      InvalidName(name, "Root element must be a message.");
+      return this;
+    }
+    // Render the special type.
+    // "<name>": {
+    //   ... Render special type ...
+    // }
+    ProtoWriter::StartObject(name);
+    status = (*type_renderer)(this, data);
+    if (!status.ok()) {
+      InvalidValue(master_type_.name(),
+                   StrCat("Field '", name, "', ", status.error_message()));
+    }
+    ProtoWriter::EndObject();
+    return this;
+  }
+
+  if (current_->IsAny()) {
+    current_->any()->RenderDataPiece(name, data);
     return this;
   }
 
   const google::protobuf::Field* field = NULL;
-  string type_url;
-  bool is_map_entry = false;
-  // We are at the root when element_ == NULL.
-  if (element_ == NULL) {
-    type_url = GetFullTypeWithUrl(master_type_.name());
-  } else {
-    if (element_->IsMap() || element_->IsStructMap()) {
-      if (!ValidMapKey(name)) return this;
-      is_map_entry = true;
-      field = StartMapEntry(name);
-    } else {
-      field = Lookup(name);
-    }
+  if (current_->IsMap()) {
+    if (!ValidMapKey(name)) return this;
+
+    // Render an item in repeated map list.
+    // { "key": "<name>", "value":
+    Push("", Item::MESSAGE, false, false);
+    ProtoWriter::RenderDataPiece("key", DataPiece(name));
+    field = Lookup("value");
     if (field == NULL) {
+      GOOGLE_LOG(DFATAL) << "Map does not have a value field.";
+      return this;
+    }
+
+    const TypeRenderer* type_renderer = FindTypeRenderer(field->type_url());
+    if (type_renderer != NULL) {
+      // Map's value type is a special type. Render it like a message:
+      // "value": {
+      //   ... Render special type ...
+      // }
+      Push("value", Item::MESSAGE, true, false);
+      status = (*type_renderer)(this, data);
+      if (!status.ok()) {
+        InvalidValue(field->type_url(),
+                     StrCat("Field '", name, "', ", status.error_message()));
+      }
+      Pop();
       return this;
     }
 
-    // Check to see if this field is a oneof and that no oneof in that group has
-    // already been set.
-    if (!ValidOneof(*field, name)) return this;
+    // If we are rendering explicit null values and the backend proto field is
+    // not of the google.protobuf.NullType type, we do nothing.
+    if (data.type() == DataPiece::TYPE_NULL &&
+        field->type_url() != kStructNullValueTypeUrl) {
+      return this;
+    }
 
-    type_url = field->type_url();
+    // Render the map value as a primitive type.
+    ProtoWriter::RenderDataPiece("value", data);
+    Pop();
+    return this;
   }
 
-  // Check if there are any well known type renderers available for type_url.
-  const TypeRenderer* type_renderer = FindTypeRenderer(type_url);
+  field = Lookup(name);
+  if (field == NULL) return this;
+
+  // Check if the field is of special type. Render it accordingly if so.
+  const TypeRenderer* type_renderer = FindTypeRenderer(field->type_url());
   if (type_renderer != NULL) {
-    // Push the current element to stack so lookups in type_renderer will
-    // find the fields. We do an EndObject soon after, which pops this. This is
-    // safe because all well-known types are messages.
-    if (element_ == NULL) {
-      element_.reset(new ProtoElement(typeinfo_, master_type_, this));
-    } else {
-      if (field) {
-        WriteTag(*field);
-        const google::protobuf::Type* type = LookupType(field);
-        element_.reset(new ProtoElement(element_.release(), field, *type,
-                                        ProtoElement::MESSAGE));
-      }
-    }
+    Push(name, Item::MESSAGE, false, false);
     status = (*type_renderer)(this, data);
     if (!status.ok()) {
-      InvalidValue(type_url,
+      InvalidValue(field->type_url(),
                    StrCat("Field '", name, "', ", status.error_message()));
     }
-    EndObject();
-    return this;
-  } else if (element_ == NULL) {  // no message type found at root
-    element_.reset(new ProtoElement(typeinfo_, master_type_, this));
-    InvalidName(name, "Root element must be a message.");
+    Pop();
     return this;
   }
 
-  if (field == NULL) {
-    return this;
-  }
-  const google::protobuf::Type* type = LookupType(field);
-  if (type == NULL) {
-    InvalidName(name,
-                StrCat("Missing descriptor for field: ", field->type_url()));
+  // If we are rendering explicit null values and the backend proto field is
+  // not of the google.protobuf.NullType type, we do nothing.
+  if (data.type() == DataPiece::TYPE_NULL &&
+      field->type_url() != kStructNullValueTypeUrl) {
     return this;
   }
 
-  // Whether we should pop at the end. Set to true if the data field is a
-  // message type, which can happen in case of struct values.
-  bool should_pop = false;
-
-  RenderSimpleDataPiece(*field, *type, data);
-
-  if (should_pop && element_ != NULL) {
-    element_.reset(element_->pop());
-  }
-
-  if (is_map_entry) {
-    // Ending map is the same as ending an object.
-    EndObject();
-  }
+  ProtoWriter::RenderDataPiece(name, data);
   return this;
 }
 
-void ProtoStreamObjectWriter::RenderSimpleDataPiece(
-    const google::protobuf::Field& field, const google::protobuf::Type& type,
-    const DataPiece& data) {
-  // If we are rendering explicit null values and the backend proto field is not
-  // of the google.protobuf.NullType type, we do nothing.
-  if (data.type() == DataPiece::TYPE_NULL &&
-      field.type_url() != kStructNullValueTypeUrl) {
-    return;
-  }
-
-  // Pushing a ProtoElement and then pop it off at the end for 2 purposes:
-  // error location reporting and required field accounting.
-  element_.reset(new ProtoElement(element_.release(), &field, type,
-                                  ProtoElement::MESSAGE));
-
-  // Make sure that field represents a simple data type.
-  if (field.kind() == google::protobuf::Field_Kind_TYPE_UNKNOWN ||
-      field.kind() == google::protobuf::Field_Kind_TYPE_MESSAGE) {
-    InvalidValue(field.type_url().empty()
-                     ? google::protobuf::Field_Kind_Name(field.kind())
-                     : field.type_url(),
-                 data.ValueAsStringOrDefault(""));
-    return;
-  }
-
-  Status status;
-  switch (field.kind()) {
-    case google::protobuf::Field_Kind_TYPE_INT32: {
-      status = WriteInt32(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_SFIXED32: {
-      status = WriteSFixed32(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_SINT32: {
-      status = WriteSInt32(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_FIXED32: {
-      status = WriteFixed32(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_UINT32: {
-      status = WriteUInt32(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_INT64: {
-      status = WriteInt64(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_SFIXED64: {
-      status = WriteSFixed64(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_SINT64: {
-      status = WriteSInt64(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_FIXED64: {
-      status = WriteFixed64(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_UINT64: {
-      status = WriteUInt64(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_DOUBLE: {
-      status = WriteDouble(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_FLOAT: {
-      status = WriteFloat(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_BOOL: {
-      status = WriteBool(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_BYTES: {
-      status = WriteBytes(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_STRING: {
-      status = WriteString(field.number(), data, stream_.get());
-      break;
-    }
-    case google::protobuf::Field_Kind_TYPE_ENUM: {
-      status = WriteEnum(field.number(), data,
-                         typeinfo_->GetEnumByTypeUrl(field.type_url()),
-                         stream_.get());
-      break;
-    }
-    default:  // TYPE_GROUP or TYPE_MESSAGE
-      status = Status(INVALID_ARGUMENT, data.ToString().ValueOrDie());
-  }
-  if (!status.ok()) {
-    InvalidValue(google::protobuf::Field_Kind_Name(field.kind()),
-                 status.error_message());
-  }
-  element_.reset(element_->pop());
-}
-
 // Map of functions that are responsible for rendering well known type
 // represented by the key.
 hash_map<string, ProtoStreamObjectWriter::TypeRenderer>*
@@ -1446,45 +1054,12 @@ ProtoStreamObjectWriter::FindTypeRenderer(const string& type_url) {
   return FindOrNull(*renderers_, type_url);
 }
 
-ProtoStreamObjectWriter::ProtoElement::ElementType
-ProtoStreamObjectWriter::GetElementType(const google::protobuf::Type& type) {
-  if (type.name() == kAnyType) {
-    return ProtoElement::ANY;
-  } else if (type.name() == kStructType) {
-    return ProtoElement::STRUCT;
-  } else if (type.name() == kStructValueType) {
-    return ProtoElement::STRUCT_VALUE;
-  } else if (type.name() == kStructListValueType) {
-    return ProtoElement::STRUCT_LIST_VALUE;
-  } else {
-    return ProtoElement::MESSAGE;
-  }
-}
-
-bool ProtoStreamObjectWriter::ValidOneof(const google::protobuf::Field& field,
-                                         StringPiece unnormalized_name) {
-  if (element_ == NULL) return true;
-
-  if (field.oneof_index() > 0) {
-    if (element_->OneofIndexTaken(field.oneof_index())) {
-      InvalidValue(
-          "oneof",
-          StrCat("oneof field '",
-                 element_->type().oneofs(field.oneof_index() - 1),
-                 "' is already set. Cannot set '", unnormalized_name, "'"));
-      return false;
-    }
-    element_->TakeOneofIndex(field.oneof_index());
-  }
-  return true;
-}
-
 bool ProtoStreamObjectWriter::ValidMapKey(StringPiece unnormalized_name) {
-  if (element_ == NULL) return true;
+  if (current_ == NULL) return true;
 
-  if (!element_->InsertMapKeyIfNotPresent(unnormalized_name)) {
-    InvalidName(
-        unnormalized_name,
+  if (!current_->InsertMapKeyIfNotPresent(unnormalized_name)) {
+    listener()->InvalidName(
+        location(), unnormalized_name,
         StrCat("Repeated map key: '", unnormalized_name, "' is already set."));
     return false;
   }
@@ -1492,134 +1067,30 @@ bool ProtoStreamObjectWriter::ValidMapKey(StringPiece unnormalized_name) {
   return true;
 }
 
-const google::protobuf::Field* ProtoStreamObjectWriter::BeginNamed(
-    StringPiece name, bool is_list) {
-  if (invalid_depth_ > 0) {
-    ++invalid_depth_;
-    return NULL;
-  }
-  const google::protobuf::Field* field = Lookup(name);
-  if (field == NULL) {
-    ++invalid_depth_;
-    // InvalidName() already called in Lookup().
-    return NULL;
-  }
-  if (is_list &&
-      field->cardinality() !=
-          google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
-    ++invalid_depth_;
-    InvalidName(name, "Proto field is not repeating, cannot start list.");
-    return NULL;
-  }
-  return field;
-}
+void ProtoStreamObjectWriter::Push(StringPiece name, Item::ItemType item_type,
+                                   bool is_placeholder, bool is_list) {
+  is_list ? ProtoWriter::StartList(name) : ProtoWriter::StartObject(name);
 
-const google::protobuf::Field* ProtoStreamObjectWriter::Lookup(
-    StringPiece unnormalized_name) {
-  ProtoElement* e = element();
-  if (e == NULL) {
-    InvalidName(unnormalized_name, "Root element must be a message.");
-    return NULL;
-  }
-  if (unnormalized_name.empty()) {
-    // Objects in repeated field inherit the same field descriptor.
-    if (e->field() == NULL) {
-      InvalidName(unnormalized_name, "Proto fields must have a name.");
-    } else if (e->field()->cardinality() !=
-               google::protobuf::Field_Cardinality_CARDINALITY_REPEATED) {
-      InvalidName(unnormalized_name, "Proto fields must have a name.");
-      return NULL;
-    }
-    return e->field();
-  }
-  const google::protobuf::Field* field =
-      typeinfo_->FindField(&e->type(), unnormalized_name);
-  if (field == NULL) InvalidName(unnormalized_name, "Cannot find field.");
-  return field;
-}
-
-const google::protobuf::Type* ProtoStreamObjectWriter::LookupType(
-    const google::protobuf::Field* field) {
-  return (field->kind() == google::protobuf::Field_Kind_TYPE_MESSAGE
-              ? typeinfo_->GetTypeByTypeUrl(field->type_url())
-              : &element_->type());
+  // invalid_depth == 0 means it is a successful StartObject or StartList.
+  if (invalid_depth() == 0)
+    current_.reset(
+        new Item(current_.release(), item_type, is_placeholder, is_list));
 }
 
-// Looks up the oneof struct field based on the data type.
-StatusOr<const google::protobuf::Field*>
-ProtoStreamObjectWriter::LookupStructField(DataPiece::Type type) {
-  const google::protobuf::Field* field = NULL;
-  switch (type) {
-    // Our JSON parser parses numbers as either int64, uint64, or double.
-    case DataPiece::TYPE_INT64:
-    case DataPiece::TYPE_UINT64:
-    case DataPiece::TYPE_DOUBLE: {
-      field = Lookup("number_value");
-      break;
-    }
-    case DataPiece::TYPE_STRING: {
-      field = Lookup("string_value");
-      break;
-    }
-    case DataPiece::TYPE_BOOL: {
-      field = Lookup("bool_value");
-      break;
-    }
-    case DataPiece::TYPE_NULL: {
-      field = Lookup("null_value");
-      break;
-    }
-    default: { return Status(INVALID_ARGUMENT, "Invalid struct data type"); }
+void ProtoStreamObjectWriter::Pop() {
+  // Pop all placeholder items sending StartObject or StartList events to
+  // ProtoWriter according to is_list value.
+  while (current_ != NULL && current_->is_placeholder()) {
+    PopOneElement();
   }
-  if (field == NULL) {
-    return Status(INVALID_ARGUMENT, "Could not lookup struct field");
+  if (current_ != NULL) {
+    PopOneElement();
   }
-  return field;
 }
 
-void ProtoStreamObjectWriter::WriteRootMessage() {
-  GOOGLE_DCHECK(!done_);
-  int curr_pos = 0;
-  // Calls the destructor of CodedOutputStream to remove any uninitialized
-  // memory from the Cord before we read it.
-  stream_.reset(NULL);
-  const void* data;
-  int length;
-  google::protobuf::io::ArrayInputStream input_stream(buffer_.data(), buffer_.size());
-  while (input_stream.Next(&data, &length)) {
-    if (length == 0) continue;
-    int num_bytes = length;
-    // Write up to where we need to insert the size field.
-    // The number of bytes we may write is the smaller of:
-    //   - the current fragment size
-    //   - the distance to the next position where a size field needs to be
-    //     inserted.
-    if (!size_insert_.empty() &&
-        size_insert_.front().pos - curr_pos < num_bytes) {
-      num_bytes = size_insert_.front().pos - curr_pos;
-    }
-    output_->Append(static_cast<const char*>(data), num_bytes);
-    if (num_bytes < length) {
-      input_stream.BackUp(length - num_bytes);
-    }
-    curr_pos += num_bytes;
-    // Insert the size field.
-    //   size_insert_.front():      the next <index, size> pair to be written.
-    //   size_insert_.front().pos:  position of the size field.
-    //   size_insert_.front().size: the size (integer) to be inserted.
-    if (!size_insert_.empty() && curr_pos == size_insert_.front().pos) {
-      // Varint32 occupies at most 10 bytes.
-      uint8 insert_buffer[10];
-      uint8* insert_buffer_pos = CodedOutputStream::WriteVarint32ToArray(
-          size_insert_.front().size, insert_buffer);
-      output_->Append(reinterpret_cast<const char*>(insert_buffer),
-                      insert_buffer_pos - insert_buffer);
-      size_insert_.pop_front();
-    }
-  }
-  output_->Flush();
-  stream_.reset(new CodedOutputStream(&adapter_));
-  done_ = true;
+void ProtoStreamObjectWriter::PopOneElement() {
+  current_->is_list() ? ProtoWriter::EndList() : ProtoWriter::EndObject();
+  current_.reset(current_->pop<Item>());
 }
 
 bool ProtoStreamObjectWriter::IsMap(const google::protobuf::Field& field) {
@@ -1630,7 +1101,7 @@ bool ProtoStreamObjectWriter::IsMap(const google::protobuf::Field& field) {
     return false;
   }
   const google::protobuf::Type* field_type =
-      typeinfo_->GetTypeByTypeUrl(field.type_url());
+      typeinfo()->GetTypeByTypeUrl(field.type_url());
 
   // TODO(xiaofeng): Unify option names.
   return GetBoolOptionOrDefault(field_type->options(),
@@ -1638,12 +1109,23 @@ bool ProtoStreamObjectWriter::IsMap(const google::protobuf::Field& field) {
          GetBoolOptionOrDefault(field_type->options(), "map_entry", false);
 }
 
-void ProtoStreamObjectWriter::WriteTag(const google::protobuf::Field& field) {
-  WireFormatLite::WireType wire_type = WireFormatLite::WireTypeForFieldType(
-      static_cast<WireFormatLite::FieldType>(field.kind()));
-  stream_->WriteTag(WireFormatLite::MakeTag(field.number(), wire_type));
+bool ProtoStreamObjectWriter::IsAny(const google::protobuf::Field& field) {
+  return GetTypeWithoutUrl(field.type_url()) == kAnyType;
 }
 
+bool ProtoStreamObjectWriter::IsStruct(const google::protobuf::Field& field) {
+  return GetTypeWithoutUrl(field.type_url()) == kStructType;
+}
+
+bool ProtoStreamObjectWriter::IsStructValue(
+    const google::protobuf::Field& field) {
+  return GetTypeWithoutUrl(field.type_url()) == kStructValueType;
+}
+
+bool ProtoStreamObjectWriter::IsStructListValue(
+    const google::protobuf::Field& field) {
+  return GetTypeWithoutUrl(field.type_url()) == kStructListValueType;
+}
 
 }  // namespace converter
 }  // namespace util
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter.h b/src/google/protobuf/util/internal/protostream_objectwriter.h
index 6e133679..08ac6e33 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter.h
+++ b/src/google/protobuf/util/internal/protostream_objectwriter.h
@@ -42,6 +42,7 @@
 #include <google/protobuf/util/internal/type_info.h>
 #include <google/protobuf/util/internal/datapiece.h>
 #include <google/protobuf/util/internal/error_listener.h>
+#include <google/protobuf/util/internal/proto_writer.h>
 #include <google/protobuf/util/internal/structured_objectwriter.h>
 #include <google/protobuf/util/type_resolver.h>
 #include <google/protobuf/stubs/bytestream.h>
@@ -67,9 +68,11 @@ namespace converter {
 class ObjectLocationTracker;
 
 // An ObjectWriter that can write protobuf bytes directly from writer events.
+// This class supports all special types like Struct and Map. It uses
+// the ProtoWriter class to write raw proto bytes.
 //
 // It also supports streaming.
-class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter {
+class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public ProtoWriter {
  public:
 // Constructor. Does not take ownership of any parameter passed in.
   ProtoStreamObjectWriter(TypeResolver* type_resolver,
@@ -82,56 +85,13 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
   virtual ProtoStreamObjectWriter* EndObject();
   virtual ProtoStreamObjectWriter* StartList(StringPiece name);
   virtual ProtoStreamObjectWriter* EndList();
-  virtual ProtoStreamObjectWriter* RenderBool(StringPiece name, bool value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderInt32(StringPiece name, int32 value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderUint32(StringPiece name,
-                                                uint32 value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderInt64(StringPiece name, int64 value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderUint64(StringPiece name,
-                                                uint64 value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderDouble(StringPiece name,
-                                                double value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderFloat(StringPiece name, float value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderString(StringPiece name,
-                                                StringPiece value) {
-    return RenderDataPiece(name, DataPiece(value));
-  }
-  virtual ProtoStreamObjectWriter* RenderBytes(StringPiece name,
-                                               StringPiece value) {
-    return RenderDataPiece(name, DataPiece(value, false));
-  }
-  virtual ProtoStreamObjectWriter* RenderNull(StringPiece name) {
-    return RenderDataPiece(name, DataPiece::NullData());
-  }
 
   // Renders a DataPiece 'value' into a field whose wire type is determined
   // from the given field 'name'.
-  ProtoStreamObjectWriter* RenderDataPiece(StringPiece name,
-                                           const DataPiece& value);
+  virtual ProtoStreamObjectWriter* RenderDataPiece(StringPiece name,
+                                                   const DataPiece& value);
 
-  // Returns the location tracker to use for tracking locations for errors.
-  const LocationTrackerInterface& location() {
-    return element_ != NULL ? *element_ : *tracker_;
-  }
-
-  // When true, we finished writing to output a complete message.
-  bool done() const { return done_; }
-
- private:
+ protected:
   // Function that renders a well known type with modified behavior.
   typedef util::Status (*TypeRenderer)(ProtoStreamObjectWriter*,
                                          const DataPiece&);
@@ -192,73 +152,37 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
     bool has_injected_value_message_;
   };
 
-  class LIBPROTOBUF_EXPORT ProtoElement : public BaseElement, public LocationTrackerInterface {
+  // Represents an item in a stack of items used to keep state between
+  // ObjectWrier events.
+  class LIBPROTOBUF_EXPORT Item : public BaseElement {
    public:
-    // Indicates the type of element. Special types like LIST, MAP, MAP_ENTRY,
-    // STRUCT etc. are used to deduce other information based on their position
-    // on the stack of elements.
-    enum ElementType {
-      MESSAGE,       // Simple message
-      LIST,          // List/repeated element
-      MAP,           // Proto3 map type
-      MAP_ENTRY,     // Proto3 map message type, with 'key' and 'value' fields
-      ANY,           // Proto3 Any type
-      STRUCT,        // Proto3 struct type
-      STRUCT_VALUE,  // Struct's Value message type
-      STRUCT_LIST,   // List type indicator within a struct
-      STRUCT_LIST_VALUE,  // Struct Value's ListValue message type
-      STRUCT_MAP,         // Struct within a struct type
-      STRUCT_MAP_ENTRY    // Struct map's entry type with 'key' and 'value'
-                          // fields
+    // Indicates the type of item.
+    enum ItemType {
+      MESSAGE,  // Simple message
+      MAP,      // Proto3 map type
+      ANY,      // Proto3 Any type
     };
 
-    // Constructor for the root element. No parent nor field.
-    ProtoElement(const TypeInfo* typeinfo, const google::protobuf::Type& type,
-                 ProtoStreamObjectWriter* enclosing);
-
-    // Constructor for a field of an element.
-    ProtoElement(ProtoElement* parent, const google::protobuf::Field* field,
-                 const google::protobuf::Type& type, ElementType element_type);
+    // Constructor for the root item.
+    Item(ProtoStreamObjectWriter* enclosing, ItemType item_type,
+         bool is_placeholder, bool is_list);
 
-    virtual ~ProtoElement() {}
+    // Constructor for a field of a message.
+    Item(Item* parent, ItemType item_type, bool is_placeholder, bool is_list);
 
-    // Called just before the destructor for clean up:
-    //   - reports any missing required fields
-    //   - computes the space needed by the size field, and augment the
-    //     length of all parent messages by this additional space.
-    //   - releases and returns the parent pointer.
-    ProtoElement* pop();
-
-    // Accessors
-    const google::protobuf::Field* field() const { return field_; }
-    const google::protobuf::Type& type() const { return type_; }
+    virtual ~Item() {}
 
     // These functions return true if the element type is corresponding to the
     // type in function name.
-    bool IsMap() { return element_type_ == MAP; }
-    bool IsStructMap() { return element_type_ == STRUCT_MAP; }
-    bool IsStructMapEntry() { return element_type_ == STRUCT_MAP_ENTRY; }
-    bool IsStructList() { return element_type_ == STRUCT_LIST; }
-    bool IsAny() { return element_type_ == ANY; }
-
-    ElementType element_type() { return element_type_; }
-
-    void RegisterField(const google::protobuf::Field* field);
-    virtual string ToString() const;
+    bool IsMap() { return item_type_ == MAP; }
+    bool IsAny() { return item_type_ == ANY; }
 
     AnyWriter* any() const { return any_.get(); }
 
-    virtual ProtoElement* parent() const {
-      return static_cast<ProtoElement*>(BaseElement::parent());
+    virtual Item* parent() const {
+      return static_cast<Item*>(BaseElement::parent());
     }
 
-    // Returns true if the index is already taken by a preceeding oneof input.
-    bool OneofIndexTaken(int32 index);
-
-    // Marks the oneof 'index' as taken. Future inputs to this oneof will
-    // generate an error.
-    void TakeOneofIndex(int32 index);
-
     // Inserts map key into hash set if and only if the key did NOT already
     // exist in hash set.
     // The hash set (map_keys_) is ONLY used to keep track of map keys.
@@ -266,6 +190,9 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
     // already present.
     bool InsertMapKeyIfNotPresent(StringPiece map_key);
 
+    bool is_placeholder() const { return is_placeholder_; }
+    bool is_list() const { return is_list_; }
+
    private:
     // Used for access to variables of the enclosing instance of
     // ProtoStreamObjectWriter.
@@ -274,126 +201,42 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
     // A writer for Any objects, handles all Any-related nonsense.
     google::protobuf::scoped_ptr<AnyWriter> any_;
 
-    // Describes the element as a field in the parent message.
-    // field_ is NULL if and only if this element is the root element.
-    const google::protobuf::Field* field_;
-
-    // TypeInfo to lookup types.
-    const TypeInfo* typeinfo_;
-
-    // Additional variables if this element is a message:
-    // (Root element is always a message).
-    // descriptor_     : describes allowed fields in the message.
-    // required_fields_: set of required fields.
-    // is_repeated_type_ : true if the element is of type list or map.
-    // size_index_     : index into ProtoStreamObjectWriter::size_insert_
-    //                   for later insertion of serialized message length.
-    const google::protobuf::Type& type_;
-    std::set<const google::protobuf::Field*> required_fields_;
-    const bool is_repeated_type_;
-    const int size_index_;
-
-    // Tracks position in repeated fields, needed for LocationTrackerInterface.
-    int array_index_;
-
     // The type of this element, see enum for permissible types.
-    ElementType element_type_;
-
-    // Set of oneof indices already seen for the type_. Used to validate
-    // incoming messages so no more than one oneof is set.
-    hash_set<int32> oneof_indices_;
+    ItemType item_type_;
 
     // Set of map keys already seen for the type_. Used to validate incoming
     // messages so no map key appears more than once.
     hash_set<string> map_keys_;
 
-    GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoElement);
-  };
+    // Conveys whether this Item is a placeholder or not. Placeholder items are
+    // pushed to stack to account for special types.
+    bool is_placeholder_;
 
-  // Container for inserting 'size' information at the 'pos' position.
-  struct SizeInfo {
-    const int pos;
-    int size;
+    // Conveys whether this Item is a list or not. This is used to send
+    // StartList or EndList calls to underlying ObjectWriter.
+    bool is_list_;
+
+    GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(Item);
   };
 
   ProtoStreamObjectWriter(const TypeInfo* typeinfo,
                           const google::protobuf::Type& type,
                           strings::ByteSink* output, ErrorListener* listener);
 
-  ProtoElement* element() { return element_.get(); }
-
-  // Helper methods for calling ErrorListener. See error_listener.h.
-  void InvalidName(StringPiece unknown_name, StringPiece message);
-  void InvalidValue(StringPiece type_name, StringPiece value);
-  void MissingField(StringPiece missing_name);
-
-  // Common code for BeginObject() and BeginList() that does invalid_depth_
-  // bookkeeping associated with name lookup.
-  const google::protobuf::Field* BeginNamed(StringPiece name, bool is_list);
-
-  // Lookup the field in the current element. Looks in the base descriptor
-  // and in any extension. This will report an error if the field cannot be
-  // found or if multiple matching extensions are found.
-  const google::protobuf::Field* Lookup(StringPiece name);
-
-  // Lookup the field type in the type descriptor. Returns NULL if the type
-  // is not known.
-  const google::protobuf::Type* LookupType(
-      const google::protobuf::Field* field);
-
-  // Looks up the oneof struct Value field depending on the type.
-  // On failure to find, it returns an appropriate error.
-  util::StatusOr<const google::protobuf::Field*> LookupStructField(
-      DataPiece::Type type);
-
-  // Starts an entry in map. This will be called after placing map element at
-  // the top of the stack. Uses this information to write map entries.
-  const google::protobuf::Field* StartMapEntry(StringPiece name);
-
-  // Starts a google.protobuf.Struct.
-  // 'field' is of type google.protobuf.Struct.
-  // If field is NULL, it indicates that the top-level message is a struct
-  // type.
-  void StartStruct(const google::protobuf::Field* field);
-
-  // Starts another struct within a struct.
-  // 'field' is of type google.protobuf.Value (see struct.proto).
-  const google::protobuf::Field* StartStructValueInStruct(
-      const google::protobuf::Field* field);
-
-  // Starts a list within a struct.
-  // 'field' is of type google.protobuf.ListValue (see struct.proto).
-  const google::protobuf::Field* StartListValueInStruct(
-      const google::protobuf::Field* field);
-
-  // Starts the repeated "values" field in struct.proto's
-  // google.protobuf.ListValue type. 'field' should be of type
-  // google.protobuf.ListValue.
-  const google::protobuf::Field* StartRepeatedValuesInListValue(
-      const google::protobuf::Field* field);
-
-  // Pops sentinel elements off the stack.
-  void SkipElements();
-
-  // Write serialized output to the final output ByteSink, inserting all
-  // the size information for nested messages that are missing from the
-  // intermediate Cord buffer.
-  void WriteRootMessage();
-
   // Returns true if the field is a map.
   bool IsMap(const google::protobuf::Field& field);
 
   // Returns true if the field is an any.
   bool IsAny(const google::protobuf::Field& field);
 
-  // Helper method to write proto tags based on the given field.
-  void WriteTag(const google::protobuf::Field& field);
+  // Returns true if the field is google.protobuf.Struct.
+  bool IsStruct(const google::protobuf::Field& field);
 
+  // Returns true if the field is google.protobuf.Value.
+  bool IsStructValue(const google::protobuf::Field& field);
 
-  // Helper function to render primitive data types in DataPiece.
-  void RenderSimpleDataPiece(const google::protobuf::Field& field,
-                             const google::protobuf::Type& type,
-                             const DataPiece& data);
+  // Returns true if the field is google.protobuf.ListValue.
+  bool IsStructListValue(const google::protobuf::Field& field);
 
   // Renders google.protobuf.Value in struct.proto. It picks the right oneof
   // type based on value's type.
@@ -417,69 +260,46 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
   static util::Status RenderWrapperType(ProtoStreamObjectWriter* ow,
                                           const DataPiece& value);
 
-  // Helper functions to create the map and find functions responsible for
-  // rendering well known types, keyed by type URL.
-  static hash_map<string, TypeRenderer>* renderers_;
   static void InitRendererMap();
   static void DeleteRendererMap();
   static TypeRenderer* FindTypeRenderer(const string& type_url);
 
-  // Returns the ProtoElement::ElementType for the given Type.
-  static ProtoElement::ElementType GetElementType(
-      const google::protobuf::Type& type);
-
-  // Returns true if the field for type_ can be set as a oneof. If field is not
-  // a oneof type, this function does nothing and returns true.
-  // If another field for this oneof is already set, this function returns
-  // false. It also calls the appropriate error callback.
-  // unnormalized_name is used for error string.
-  bool ValidOneof(const google::protobuf::Field& field,
-                  StringPiece unnormalized_name);
-
   // Returns true if the map key for type_ is not duplicated key.
   // If map key is duplicated key, this function returns false.
-  // Note that caller should make sure that the current proto element (element_)
+  // Note that caller should make sure that the current proto element (current_)
   // is of element type MAP or STRUCT_MAP.
   // It also calls the appropriate error callback and unnormalzied_name is used
   // for error string.
   bool ValidMapKey(StringPiece unnormalized_name);
 
+  // Pushes an item on to the stack. Also calls either StartObject or StartList
+  // on the underlying ObjectWriter depending on whether is_list is false or
+  // not.
+  // is_placeholder conveys whether the item is a placeholder item or not.
+  // Placeholder items are pushed when adding auxillary types' StartObject or
+  // StartList calls.
+  void Push(StringPiece name, Item::ItemType item_type, bool is_placeholder,
+            bool is_list);
+
+  // Pops items from the stack. All placeholder items are popped until a
+  // non-placeholder item is found.
+  void Pop();
+
+  // Pops one element from the stack. Calls EndObject() or EndList() on the
+  // underlying ObjectWriter depending on the value of is_list_.
+  void PopOneElement();
+
+ private:
+  // Helper functions to create the map and find functions responsible for
+  // rendering well known types, keyed by type URL.
+  static hash_map<string, TypeRenderer>* renderers_;
+
   // Variables for describing the structure of the input tree:
   // master_type_: descriptor for the whole protobuf message.
-  // typeinfo_ : the TypeInfo object to lookup types.
   const google::protobuf::Type& master_type_;
-  const TypeInfo* typeinfo_;
-  // Whether we own the typeinfo_ object.
-  bool own_typeinfo_;
-
-  // Indicates whether we finished writing root message completely.
-  bool done_;
-
-  // Variable for internal state processing:
-  // element_    : the current element.
-  // size_insert_: sizes of nested messages.
-  //               pos  - position to insert the size field.
-  //               size - size value to be inserted.
-  google::protobuf::scoped_ptr<ProtoElement> element_;
-  std::deque<SizeInfo> size_insert_;
-
-  // Variables for output generation:
-  // output_  : pointer to an external ByteSink for final user-visible output.
-  // buffer_  : buffer holding partial message before being ready for output_.
-  // adapter_ : internal adapter between CodedOutputStream and Cord buffer_.
-  // stream_  : wrapper for writing tags and other encodings in wire format.
-  strings::ByteSink* output_;
-  string buffer_;
-  google::protobuf::io::StringOutputStream adapter_;
-  google::protobuf::scoped_ptr<google::protobuf::io::CodedOutputStream> stream_;
-
-  // Variables for error tracking and reporting:
-  // listener_     : a place to report any errors found.
-  // invalid_depth_: number of enclosing invalid nested messages.
-  // tracker_      : the root location tracker interface.
-  ErrorListener* listener_;
-  int invalid_depth_;
-  google::protobuf::scoped_ptr<LocationTrackerInterface> tracker_;
+
+  // The current element, variable for internal state processing.
+  google::protobuf::scoped_ptr<Item> current_;
 
   GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoStreamObjectWriter);
 };
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter_test.cc b/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
index cb9f97f7..c7667c21 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
+++ b/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
@@ -241,6 +241,21 @@ TEST_P(ProtoStreamObjectWriterTest, SimpleMessage) {
   CheckOutput(book);
 }
 
+TEST_P(ProtoStreamObjectWriterTest, CustomJsonName) {
+  Book book;
+  Author* robert = book.mutable_author();
+  robert->set_id(12345);
+  robert->set_name("robert");
+
+  ow_->StartObject("")
+      ->StartObject("author")
+      ->RenderUint64("@id", 12345)
+      ->RenderString("name", "robert")
+      ->EndObject()
+      ->EndObject();
+  CheckOutput(book);
+}
+
 TEST_P(ProtoStreamObjectWriterTest, PrimitiveFromStringConversion) {
   Primitive full;
   full.set_fix32(101);
@@ -796,10 +811,6 @@ TEST_P(ProtoStreamObjectWriterTest, RootNamedList) {
               InvalidName(_, StringPiece("oops"),
                           StringPiece("Root element should not be named.")))
       .With(Args<0>(HasObjectLocation("")));
-  EXPECT_CALL(listener_,
-              InvalidName(_, StringPiece(""),
-                          StringPiece("Proto fields must have a name.")))
-      .With(Args<0>(HasObjectLocation("")));
   ow_->StartList("oops")->RenderString("", "item")->EndList();
   CheckOutput(empty, 0);
 }
@@ -864,6 +875,18 @@ INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
                         ::testing::Values(
                             testing::USE_TYPE_RESOLVER));
 
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, ParseTimestamp) {
+  TimestampDuration timestamp;
+  google::protobuf::Timestamp* ts = timestamp.mutable_ts();
+  ts->set_seconds(1448249855);
+  ts->set_nanos(33155000);
+
+  ow_->StartObject("")
+      ->RenderString("ts", "2015-11-23T03:37:35.033155Z")
+      ->EndObject();
+  CheckOutput(timestamp);
+}
+
 TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError1) {
   TimestampDuration timestamp;
 
@@ -922,9 +945,66 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError4) {
   CheckOutput(timestamp);
 }
 
-// TODO(skarvaje): Write a test for nanos that exceed limit. Currently, it is
-// not possible to construct a test case where nanos exceed limit because of
-// floating point arithmetic.
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError5) {
+  TimestampDuration timestamp;
+
+  EXPECT_CALL(
+      listener_,
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: "
+                               "2015-11-23T03:37:35.033155   Z")));
+
+  ow_->StartObject("")
+      // Whitespace in the Timestamp nanos is not allowed.
+      ->RenderString("ts", "2015-11-23T03:37:35.033155   Z")
+      ->EndObject();
+  CheckOutput(timestamp);
+}
+
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError6) {
+  TimestampDuration timestamp;
+
+  EXPECT_CALL(
+      listener_,
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: "
+                               "2015-11-23T03:37:35.033155 1234Z")));
+
+  ow_->StartObject("")
+      // Whitespace in the Timestamp nanos is not allowed.
+      ->RenderString("ts", "2015-11-23T03:37:35.033155 1234Z")
+      ->EndObject();
+  CheckOutput(timestamp);
+}
+
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError7) {
+  TimestampDuration timestamp;
+
+  EXPECT_CALL(
+      listener_,
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: "
+                               "2015-11-23T03:37:35.033abc155Z")));
+
+  ow_->StartObject("")
+      // Non-numeric characters in the Timestamp nanos is not allowed.
+      ->RenderString("ts", "2015-11-23T03:37:35.033abc155Z")
+      ->EndObject();
+  CheckOutput(timestamp);
+}
+
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, ParseDuration) {
+  TimestampDuration duration;
+  google::protobuf::Duration* dur = duration.mutable_dur();
+  dur->set_seconds(1448216930);
+  dur->set_nanos(132262000);
+
+  ow_->StartObject("")->RenderString("dur", "1448216930.132262s")->EndObject();
+  CheckOutput(duration);
+}
 
 TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidDurationError1) {
   TimestampDuration duration;
@@ -962,7 +1042,7 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidDurationError3) {
       InvalidValue(
           _, StringPiece("type.googleapis.com/google.protobuf.Duration"),
           StringPiece("Field 'dur', Invalid duration format, failed to "
-                      "parse nanos seconds")));
+                      "parse nano seconds")));
 
   ow_->StartObject("")->RenderString("dur", "123.DEFs")->EndObject();
   CheckOutput(duration);
@@ -981,6 +1061,19 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidDurationError4) {
   CheckOutput(duration);
 }
 
+TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidDurationError5) {
+  TimestampDuration duration;
+
+  EXPECT_CALL(
+      listener_,
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Duration"),
+                   StringPiece("Field 'dur', Duration value exceeds limits")));
+
+  ow_->StartObject("")->RenderString("dur", "0.1000000001s")->EndObject();
+  CheckOutput(duration);
+}
+
 TEST_P(ProtoStreamObjectWriterTimestampDurationTest,
        MismatchedTimestampTypeInput) {
   TimestampDuration timestamp;
@@ -1066,12 +1159,12 @@ TEST_P(ProtoStreamObjectWriterStructTest, StructInvalidInputFailure) {
 TEST_P(ProtoStreamObjectWriterStructTest, SimpleRepeatedStructMapKeyTest) {
   EXPECT_CALL(
       listener_,
-      InvalidName(_, StringPiece("k1"),
-                  StringPiece("Repeated map key: 'k1' is already set.")));
+      InvalidName(_, StringPiece("gBike"),
+                  StringPiece("Repeated map key: 'gBike' is already set.")));
   ow_->StartObject("")
       ->StartObject("object")
-      ->RenderString("k1", "v1")
-      ->RenderString("k1", "v2")
+      ->RenderString("gBike", "v1")
+      ->RenderString("gBike", "v2")
       ->EndObject()
       ->EndObject();
 }
@@ -1121,10 +1214,11 @@ INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
 
 TEST_P(ProtoStreamObjectWriterMapTest, MapShouldNotAcceptList) {
   MapIn mm;
-  EXPECT_CALL(listener_,
-              InvalidValue(_, StringPiece("Map"),
-                           StringPiece("Cannot bind a list to map.")))
-      .With(Args<0>(HasObjectLocation("map_input")));
+  EXPECT_CALL(
+      listener_,
+      InvalidValue(
+          _, StringPiece("Map"),
+          StringPiece("Cannot bind a list to map for field 'map_input'.")));
   ow_->StartObject("")
       ->StartList("map_input")
       ->RenderString("a", "b")
diff --git a/src/google/protobuf/util/internal/testdata/books.proto b/src/google/protobuf/util/internal/testdata/books.proto
index 6e2f109b..82b81760 100644
--- a/src/google/protobuf/util/internal/testdata/books.proto
+++ b/src/google/protobuf/util/internal/testdata/books.proto
@@ -66,7 +66,7 @@ message Publisher {
 
 // An author of a book
 message Author {
-  optional uint64 id = 1;
+  optional uint64 id = 1 [json_name = "@id"];
   optional string name = 2;
   repeated string pseudonym = 3;
   optional bool alive = 4;
diff --git a/src/google/protobuf/util/internal/testdata/default_value.proto b/src/google/protobuf/util/internal/testdata/default_value.proto
index ebbdf6ab..cccc741c 100644
--- a/src/google/protobuf/util/internal/testdata/default_value.proto
+++ b/src/google/protobuf/util/internal/testdata/default_value.proto
@@ -75,9 +75,10 @@ message DefaultValueTestCases {
   IntToStringMap int_to_string = 403;
   MixedMap mixed1 = 404;
   MixedMap2 mixed2 = 405;
-  MessageMap map_of_objects = 406;
-  MixedMap mixed_empty = 407;
-  MessageMap message_map_empty = 408;
+  MixedMap2 empty_mixed2 = 406;
+  MessageMap map_of_objects = 407;
+  MixedMap mixed_empty = 408;
+  MessageMap message_map_empty = 409;
   DoubleValueMessage double_value = 501;
   DoubleValueMessage double_value_default = 502;
 }
diff --git a/src/google/protobuf/util/internal/testdata/default_value_test.proto b/src/google/protobuf/util/internal/testdata/default_value_test.proto
index 21b85e6d..93288341 100644
--- a/src/google/protobuf/util/internal/testdata/default_value_test.proto
+++ b/src/google/protobuf/util/internal/testdata/default_value_test.proto
@@ -43,4 +43,11 @@ message DefaultValueTest {
   bool bool_value = 13;
   string string_value = 15;
   bytes bytes_value = 17 [ctype = CORD];
+
+  enum EnumDefault {
+    ENUM_FIRST = 0;
+    ENUM_SECOND = 1;
+    ENUM_THIRD = 2;
+  }
+  EnumDefault enum_value = 18;
 }
diff --git a/src/google/protobuf/util/internal/type_info.cc b/src/google/protobuf/util/internal/type_info.cc
index a45a76e3..00a8ee7a 100644
--- a/src/google/protobuf/util/internal/type_info.cc
+++ b/src/google/protobuf/util/internal/type_info.cc
@@ -136,8 +136,7 @@ class TypeInfoForTypeResolver : public TypeInfo {
     for (int i = 0; i < type->fields_size(); ++i) {
       const google::protobuf::Field& field = type->fields(i);
       StringPiece name = field.name();
-      StringPiece camel_case_name =
-          *string_storage_.insert(ToCamelCase(name)).first;
+      StringPiece camel_case_name = field.json_name();
       const StringPiece* existing = InsertOrReturnExisting(
           &camel_case_name_table_, camel_case_name, name);
       if (existing && *existing != name) {
diff --git a/src/google/protobuf/util/internal/utility.cc b/src/google/protobuf/util/internal/utility.cc
index 61899c24..1ddf2487 100644
--- a/src/google/protobuf/util/internal/utility.cc
+++ b/src/google/protobuf/util/internal/utility.cc
@@ -49,7 +49,8 @@ namespace converter {
 namespace {
 const StringPiece SkipWhiteSpace(StringPiece str) {
   StringPiece::size_type i;
-  for (i = 0; i < str.size() && isspace(str[i]); ++i) {}
+  for (i = 0; i < str.size() && isspace(str[i]); ++i) {
+  }
   GOOGLE_DCHECK(i == str.size() || !isspace(str[i]));
   return StringPiece(str, i);
 }
@@ -160,6 +161,19 @@ const google::protobuf::Field* FindFieldInTypeOrNull(
   return NULL;
 }
 
+const google::protobuf::Field* FindJsonFieldInTypeOrNull(
+    const google::protobuf::Type* type, StringPiece json_name) {
+  if (type != NULL) {
+    for (int i = 0; i < type->fields_size(); ++i) {
+      const google::protobuf::Field& field = type->fields(i);
+      if (field.json_name() == json_name) {
+        return &field;
+      }
+    }
+  }
+  return NULL;
+}
+
 const google::protobuf::EnumValue* FindEnumValueByNameOrNull(
     const google::protobuf::Enum* enum_type, StringPiece enum_name) {
   if (enum_type != NULL) {
@@ -316,16 +330,23 @@ string FloatAsString(float value) {
   return DoubleAsString(value);
 }
 
-bool SafeStrToFloat(StringPiece str, float *value) {
+bool SafeStrToFloat(StringPiece str, float* value) {
   double double_value;
   if (!safe_strtod(str, &double_value)) {
     return false;
   }
-  *value = static_cast<float>(double_value);
 
-  if (MathLimits<float>::IsInf(*value)) {
+  if (MathLimits<double>::IsInf(double_value) ||
+      MathLimits<double>::IsNaN(double_value))
+    return false;
+
+  // Fail if the value is not representable in float.
+  if (double_value > std::numeric_limits<float>::max() ||
+      double_value < -std::numeric_limits<float>::max()) {
     return false;
   }
+
+  *value = static_cast<float>(double_value);
   return true;
 }
 
diff --git a/src/google/protobuf/util/internal/utility.h b/src/google/protobuf/util/internal/utility.h
index 5ba97bd2..33df8eda 100644
--- a/src/google/protobuf/util/internal/utility.h
+++ b/src/google/protobuf/util/internal/utility.h
@@ -127,6 +127,11 @@ const google::protobuf::Option* FindOptionOrNull(
 const google::protobuf::Field* FindFieldInTypeOrNull(
     const google::protobuf::Type* type, StringPiece field_name);
 
+// Similar to FindFieldInTypeOrNull, but this looks up fields with given
+// json_name.
+const google::protobuf::Field* FindJsonFieldInTypeOrNull(
+    const google::protobuf::Type* type, StringPiece json_name);
+
 // Finds and returns the EnumValue identified by enum_name in the passed tech
 // Enum object. Returns NULL if none found.
 const google::protobuf::EnumValue* FindEnumValueByNameOrNull(
diff --git a/src/google/protobuf/util/json_format_proto3.proto b/src/google/protobuf/util/json_format_proto3.proto
index e8137677..a1e24c18 100644
--- a/src/google/protobuf/util/json_format_proto3.proto
+++ b/src/google/protobuf/util/json_format_proto3.proto
@@ -165,3 +165,12 @@ message TestListValue {
   google.protobuf.ListValue value = 1;
   repeated google.protobuf.ListValue repeated_value = 2;
 }
+
+message TestBoolValue {
+  bool bool_value = 1;
+  map<bool, int32> bool_map = 2;
+}
+
+message TestCustomJsonName {
+  int32 value = 1 [json_name = "@value"];
+}
diff --git a/src/google/protobuf/util/message_differencer.cc b/src/google/protobuf/util/message_differencer.cc
index 47237e5a..0f879dc7 100644
--- a/src/google/protobuf/util/message_differencer.cc
+++ b/src/google/protobuf/util/message_differencer.cc
@@ -238,9 +238,25 @@ void MessageDifferencer::TreatAsSet(const FieldDescriptor* field) {
   GOOGLE_CHECK(key_comparator == NULL)
       << "Cannot treat this repeated field as both Map and Set for"
       << " comparison.  Field name is: " << field->full_name();
+  GOOGLE_CHECK(list_fields_.find(field) == list_fields_.end())
+      << "Cannot treat the same field as both SET and LIST. Field name is: "
+      << field->full_name();
   set_fields_.insert(field);
 }
 
+void MessageDifferencer::TreatAsList(const FieldDescriptor* field) {
+  GOOGLE_CHECK(field->is_repeated()) << "Field must be repeated: "
+                              << field->full_name();
+  const MapKeyComparator* key_comparator = GetMapKeyComparator(field);
+  GOOGLE_CHECK(key_comparator == NULL)
+      << "Cannot treat this repeated field as both Map and Set for"
+      << " comparison.  Field name is: " << field->full_name();
+  GOOGLE_CHECK(set_fields_.find(field) == set_fields_.end())
+      << "Cannot treat the same field as both SET and LIST. Field name is: "
+      << field->full_name();
+  list_fields_.insert(field);
+}
+
 void MessageDifferencer::TreatAsMap(const FieldDescriptor* field,
                                     const FieldDescriptor* key) {
   GOOGLE_CHECK(field->is_repeated()) << "Field must be repeated: "
@@ -255,6 +271,9 @@ void MessageDifferencer::TreatAsMap(const FieldDescriptor* field,
   GOOGLE_CHECK(set_fields_.find(field) == set_fields_.end())
       << "Cannot treat this repeated field as both Map and Set for "
       << "comparison.";
+  GOOGLE_CHECK(list_fields_.find(field) == list_fields_.end())
+      << "Cannot treat this repeated field as both Map and List for "
+      << "comparison.";
   MapKeyComparator* key_comparator =
       new MultipleFieldsMapKeyComparator(this, key);
   owned_key_comparators_.push_back(key_comparator);
@@ -920,7 +939,8 @@ bool MessageDifferencer::CheckPathChanged(
 bool MessageDifferencer::IsTreatedAsSet(const FieldDescriptor* field) {
   if (!field->is_repeated()) return false;
   if (field->is_map()) return true;
-  if (repeated_field_comparison_ == AS_SET) return true;
+  if (repeated_field_comparison_ == AS_SET)
+    return list_fields_.find(field) == list_fields_.end();
   return (set_fields_.find(field) != set_fields_.end());
 }
 
diff --git a/src/google/protobuf/util/message_differencer.h b/src/google/protobuf/util/message_differencer.h
index 34c173db..3ea74e67 100644
--- a/src/google/protobuf/util/message_differencer.h
+++ b/src/google/protobuf/util/message_differencer.h
@@ -397,9 +397,16 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
   // + n^3) in which n^3 is the time complexity of the maximum matching
   // algorithm.
   //
-  // REQUIRES:  field->is_repeated()
+  // REQUIRES:  field->is_repeated() and field not registered with TreatAsList
   void TreatAsSet(const FieldDescriptor* field);
 
+  // The elements of the given repeated field will be treated as a list for
+  // diffing purposes, so different orderings of the same elements will NOT be
+  // considered equal.
+  //
+  // REQUIRED: field->is_repeated() and field not registered with TreatAsSet
+  void TreatAsList(const FieldDescriptor* field);
+
   // The elements of the given repeated field will be treated as a map for
   // diffing purposes, with |key| being the map key.  Thus, elements with the
   // same key will be compared even if they do not appear at the same index.
@@ -791,6 +798,7 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
   RepeatedFieldComparison repeated_field_comparison_;
 
   FieldSet set_fields_;
+  FieldSet list_fields_;
   // Keeps track of MapKeyComparators that are created within
   // MessageDifferencer. These MapKeyComparators should be deleted
   // before MessageDifferencer is destroyed.
diff --git a/src/google/protobuf/util/message_differencer_unittest.cc b/src/google/protobuf/util/message_differencer_unittest.cc
index 701b94ae..4e9ca348 100755
--- a/src/google/protobuf/util/message_differencer_unittest.cc
+++ b/src/google/protobuf/util/message_differencer_unittest.cc
@@ -1103,12 +1103,19 @@ TEST(MessageDifferencerTest, RepeatedFieldSetTest_Combination) {
   msg1.add_rw("change"); msg2.add_rw("change");
 
   // Compare
-  util::MessageDifferencer differencer;
-  differencer.TreatAsMap(msg1.GetDescriptor()->FindFieldByName("item"),
-                         item->GetDescriptor()->FindFieldByName("a"));
-  differencer.TreatAsSet(msg1.GetDescriptor()->FindFieldByName("rv"));
-  differencer.TreatAsSet(item->GetDescriptor()->FindFieldByName("ra"));
-  EXPECT_TRUE(differencer.Compare(msg1, msg2));
+  util::MessageDifferencer differencer1;
+  differencer1.TreatAsMap(msg1.GetDescriptor()->FindFieldByName("item"),
+                          item->GetDescriptor()->FindFieldByName("a"));
+  differencer1.TreatAsSet(msg1.GetDescriptor()->FindFieldByName("rv"));
+  differencer1.TreatAsSet(item->GetDescriptor()->FindFieldByName("ra"));
+  EXPECT_TRUE(differencer1.Compare(msg1, msg2));
+
+  util::MessageDifferencer differencer2;
+  differencer2.TreatAsMap(msg1.GetDescriptor()->FindFieldByName("item"),
+                          item->GetDescriptor()->FindFieldByName("a"));
+  differencer2.set_repeated_field_comparison(util::MessageDifferencer::AS_SET);
+  differencer2.TreatAsList(msg1.GetDescriptor()->FindFieldByName("rw"));
+  EXPECT_TRUE(differencer2.Compare(msg1, msg2));
 }
 
 TEST(MessageDifferencerTest, RepeatedFieldMapTest_Partial) {
@@ -1168,6 +1175,11 @@ TEST(MessageDifferencerTest, RepeatedFieldSetTest_Duplicates) {
   differencer.TreatAsSet(GetFieldDescriptor(a, "rv"));
   EXPECT_TRUE(differencer.Compare(b, a));
   EXPECT_FALSE(differencer.Compare(c, a));
+
+  util::MessageDifferencer differencer1;
+  differencer1.set_repeated_field_comparison(util::MessageDifferencer::AS_SET);
+  EXPECT_TRUE(differencer1.Compare(b, a));
+  EXPECT_FALSE(differencer1.Compare(c, a));
 }
 
 TEST(MessageDifferencerTest, RepeatedFieldSetTest_PartialSimple) {
diff --git a/src/google/protobuf/util/type_resolver_util.cc b/src/google/protobuf/util/type_resolver_util.cc
index a0996954..96393903 100644
--- a/src/google/protobuf/util/type_resolver_util.cc
+++ b/src/google/protobuf/util/type_resolver_util.cc
@@ -159,7 +159,10 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     }
     field->set_number(descriptor->number());
     field->set_name(descriptor->name());
-    field->set_json_name(converter::ToCamelCase(descriptor->name()));
+    field->set_json_name(descriptor->json_name());
+    if (descriptor->has_default_value()) {
+      field->set_default_value(DefaultValueAsString(descriptor));
+    }
     if (descriptor->type() == FieldDescriptor::TYPE_MESSAGE) {
       field->set_type_url(GetTypeUrl(descriptor->message_type()));
     } else if (descriptor->type() == FieldDescriptor::TYPE_ENUM) {
@@ -200,6 +203,46 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     return url_prefix_ + "/" + descriptor->full_name();
   }
 
+  string DefaultValueAsString(const FieldDescriptor* descriptor) {
+    switch (descriptor->cpp_type()) {
+      case FieldDescriptor::CPPTYPE_INT32:
+        return SimpleItoa(descriptor->default_value_int32());
+        break;
+      case FieldDescriptor::CPPTYPE_INT64:
+        return SimpleItoa(descriptor->default_value_int64());
+        break;
+      case FieldDescriptor::CPPTYPE_UINT32:
+        return SimpleItoa(descriptor->default_value_uint32());
+        break;
+      case FieldDescriptor::CPPTYPE_UINT64:
+        return SimpleItoa(descriptor->default_value_uint64());
+        break;
+      case FieldDescriptor::CPPTYPE_FLOAT:
+        return SimpleFtoa(descriptor->default_value_float());
+        break;
+      case FieldDescriptor::CPPTYPE_DOUBLE:
+        return SimpleDtoa(descriptor->default_value_double());
+        break;
+      case FieldDescriptor::CPPTYPE_BOOL:
+        return descriptor->default_value_bool() ? "true" : "false";
+        break;
+      case FieldDescriptor::CPPTYPE_STRING:
+        if (descriptor->type() == FieldDescriptor::TYPE_BYTES) {
+          return CEscape(descriptor->default_value_string());
+        } else {
+          return descriptor->default_value_string();
+        }
+        break;
+      case FieldDescriptor::CPPTYPE_ENUM:
+        return descriptor->default_value_enum()->name();
+        break;
+      case FieldDescriptor::CPPTYPE_MESSAGE:
+        GOOGLE_LOG(DFATAL) << "Messages can't have default values!";
+        break;
+    }
+    return "";
+  }
+
   string url_prefix_;
   const DescriptorPool* pool_;
 };
diff --git a/src/google/protobuf/util/type_resolver_util_test.cc b/src/google/protobuf/util/type_resolver_util_test.cc
index 74b2d0da..8a0bf652 100644
--- a/src/google/protobuf/util/type_resolver_util_test.cc
+++ b/src/google/protobuf/util/type_resolver_util_test.cc
@@ -43,6 +43,7 @@
 #include <google/protobuf/map_unittest.pb.h>
 #include <google/protobuf/test_util.h>
 #include <google/protobuf/unittest.pb.h>
+#include <google/protobuf/util/json_format_proto3.pb.h>
 #include <google/protobuf/util/type_resolver.h>
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
@@ -332,6 +333,19 @@ TEST_F(DescriptorPoolTypeResolverTest, TestEnum) {
   EnumHasValue(type, "NEG", -1);
 }
 
+TEST_F(DescriptorPoolTypeResolverTest, TestJsonName) {
+  Type type;
+  ASSERT_TRUE(resolver_->ResolveMessageType(
+                           GetTypeUrl<protobuf_unittest::TestAllTypes>(), &type)
+                  .ok());
+  EXPECT_EQ("optionalInt32", FindField(type, "optional_int32")->json_name());
+
+  ASSERT_TRUE(resolver_->ResolveMessageType(
+                           GetTypeUrl<proto3::TestCustomJsonName>(), &type)
+                  .ok());
+  EXPECT_EQ("@value", FindField(type, "value")->json_name());
+}
+
 }  // namespace
 }  // namespace util
 }  // namespace protobuf
diff --git a/src/google/protobuf/wrappers.pb.cc b/src/google/protobuf/wrappers.pb.cc
index e153687b..212dd219 100644
--- a/src/google/protobuf/wrappers.pb.cc
+++ b/src/google/protobuf/wrappers.pb.cc
@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/stubs/once.h>
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/wire_format_lite_inl.h>
@@ -262,10 +263,10 @@ void protobuf_AddDesc_google_2fprotobuf_2fwrappers_2eproto() {
     "e\030\001 \001(\004\"\033\n\nInt32Value\022\r\n\005value\030\001 \001(\005\"\034\n\013"
     "UInt32Value\022\r\n\005value\030\001 \001(\r\"\032\n\tBoolValue\022"
     "\r\n\005value\030\001 \001(\010\"\034\n\013StringValue\022\r\n\005value\030\001"
-    " \001(\t\"\033\n\nBytesValue\022\r\n\005value\030\001 \001(\014BP\n\023com"
-    ".google.protobufB\rWrappersProtoP\001\240\001\001\242\002\003G"
-    "PB\252\002\036Google.Protobuf.WellKnownTypesb\006pro"
-    "to3", 403);
+    " \001(\t\"\033\n\nBytesValue\022\r\n\005value\030\001 \001(\014BS\n\023com"
+    ".google.protobufB\rWrappersProtoP\001\240\001\001\370\001\001\242"
+    "\002\003GPB\252\002\036Google.Protobuf.WellKnownTypesb\006"
+    "proto3", 406);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/wrappers.proto", &protobuf_RegisterTypes);
   DoubleValue::default_instance_ = new DoubleValue();
@@ -318,6 +319,14 @@ DoubleValue::DoubleValue()
   // @@protoc_insertion_point(constructor:google.protobuf.DoubleValue)
 }
 
+DoubleValue::DoubleValue(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.DoubleValue)
+}
+
 void DoubleValue::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -342,10 +351,20 @@ DoubleValue::~DoubleValue() {
 }
 
 void DoubleValue::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void DoubleValue::ArenaDtor(void* object) {
+  DoubleValue* _this = reinterpret_cast< DoubleValue* >(object);
+  (void)_this;
+}
+void DoubleValue::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void DoubleValue::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -364,11 +383,7 @@ const DoubleValue& DoubleValue::default_instance() {
 DoubleValue* DoubleValue::default_instance_ = NULL;
 
 DoubleValue* DoubleValue::New(::google::protobuf::Arena* arena) const {
-  DoubleValue* n = new DoubleValue;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<DoubleValue>(arena);
 }
 
 void DoubleValue::Clear() {
@@ -495,6 +510,18 @@ bool DoubleValue::IsInitialized() const {
 
 void DoubleValue::Swap(DoubleValue* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    DoubleValue temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void DoubleValue::UnsafeArenaSwap(DoubleValue* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void DoubleValue::InternalSwap(DoubleValue* other) {
@@ -542,6 +569,14 @@ FloatValue::FloatValue()
   // @@protoc_insertion_point(constructor:google.protobuf.FloatValue)
 }
 
+FloatValue::FloatValue(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.FloatValue)
+}
+
 void FloatValue::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -566,10 +601,20 @@ FloatValue::~FloatValue() {
 }
 
 void FloatValue::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void FloatValue::ArenaDtor(void* object) {
+  FloatValue* _this = reinterpret_cast< FloatValue* >(object);
+  (void)_this;
+}
+void FloatValue::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void FloatValue::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -588,11 +633,7 @@ const FloatValue& FloatValue::default_instance() {
 FloatValue* FloatValue::default_instance_ = NULL;
 
 FloatValue* FloatValue::New(::google::protobuf::Arena* arena) const {
-  FloatValue* n = new FloatValue;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<FloatValue>(arena);
 }
 
 void FloatValue::Clear() {
@@ -719,6 +760,18 @@ bool FloatValue::IsInitialized() const {
 
 void FloatValue::Swap(FloatValue* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    FloatValue temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void FloatValue::UnsafeArenaSwap(FloatValue* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void FloatValue::InternalSwap(FloatValue* other) {
@@ -766,6 +819,14 @@ Int64Value::Int64Value()
   // @@protoc_insertion_point(constructor:google.protobuf.Int64Value)
 }
 
+Int64Value::Int64Value(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.Int64Value)
+}
+
 void Int64Value::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -790,10 +851,20 @@ Int64Value::~Int64Value() {
 }
 
 void Int64Value::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void Int64Value::ArenaDtor(void* object) {
+  Int64Value* _this = reinterpret_cast< Int64Value* >(object);
+  (void)_this;
+}
+void Int64Value::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void Int64Value::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -812,11 +883,7 @@ const Int64Value& Int64Value::default_instance() {
 Int64Value* Int64Value::default_instance_ = NULL;
 
 Int64Value* Int64Value::New(::google::protobuf::Arena* arena) const {
-  Int64Value* n = new Int64Value;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<Int64Value>(arena);
 }
 
 void Int64Value::Clear() {
@@ -945,6 +1012,18 @@ bool Int64Value::IsInitialized() const {
 
 void Int64Value::Swap(Int64Value* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    Int64Value temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void Int64Value::UnsafeArenaSwap(Int64Value* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void Int64Value::InternalSwap(Int64Value* other) {
@@ -992,6 +1071,14 @@ UInt64Value::UInt64Value()
   // @@protoc_insertion_point(constructor:google.protobuf.UInt64Value)
 }
 
+UInt64Value::UInt64Value(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.UInt64Value)
+}
+
 void UInt64Value::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -1016,10 +1103,20 @@ UInt64Value::~UInt64Value() {
 }
 
 void UInt64Value::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void UInt64Value::ArenaDtor(void* object) {
+  UInt64Value* _this = reinterpret_cast< UInt64Value* >(object);
+  (void)_this;
+}
+void UInt64Value::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void UInt64Value::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -1038,11 +1135,7 @@ const UInt64Value& UInt64Value::default_instance() {
 UInt64Value* UInt64Value::default_instance_ = NULL;
 
 UInt64Value* UInt64Value::New(::google::protobuf::Arena* arena) const {
-  UInt64Value* n = new UInt64Value;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<UInt64Value>(arena);
 }
 
 void UInt64Value::Clear() {
@@ -1171,6 +1264,18 @@ bool UInt64Value::IsInitialized() const {
 
 void UInt64Value::Swap(UInt64Value* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    UInt64Value temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void UInt64Value::UnsafeArenaSwap(UInt64Value* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void UInt64Value::InternalSwap(UInt64Value* other) {
@@ -1218,6 +1323,14 @@ Int32Value::Int32Value()
   // @@protoc_insertion_point(constructor:google.protobuf.Int32Value)
 }
 
+Int32Value::Int32Value(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.Int32Value)
+}
+
 void Int32Value::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -1242,10 +1355,20 @@ Int32Value::~Int32Value() {
 }
 
 void Int32Value::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void Int32Value::ArenaDtor(void* object) {
+  Int32Value* _this = reinterpret_cast< Int32Value* >(object);
+  (void)_this;
+}
+void Int32Value::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void Int32Value::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -1264,11 +1387,7 @@ const Int32Value& Int32Value::default_instance() {
 Int32Value* Int32Value::default_instance_ = NULL;
 
 Int32Value* Int32Value::New(::google::protobuf::Arena* arena) const {
-  Int32Value* n = new Int32Value;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<Int32Value>(arena);
 }
 
 void Int32Value::Clear() {
@@ -1397,6 +1516,18 @@ bool Int32Value::IsInitialized() const {
 
 void Int32Value::Swap(Int32Value* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    Int32Value temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void Int32Value::UnsafeArenaSwap(Int32Value* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void Int32Value::InternalSwap(Int32Value* other) {
@@ -1444,6 +1575,14 @@ UInt32Value::UInt32Value()
   // @@protoc_insertion_point(constructor:google.protobuf.UInt32Value)
 }
 
+UInt32Value::UInt32Value(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.UInt32Value)
+}
+
 void UInt32Value::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -1468,10 +1607,20 @@ UInt32Value::~UInt32Value() {
 }
 
 void UInt32Value::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void UInt32Value::ArenaDtor(void* object) {
+  UInt32Value* _this = reinterpret_cast< UInt32Value* >(object);
+  (void)_this;
+}
+void UInt32Value::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void UInt32Value::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -1490,11 +1639,7 @@ const UInt32Value& UInt32Value::default_instance() {
 UInt32Value* UInt32Value::default_instance_ = NULL;
 
 UInt32Value* UInt32Value::New(::google::protobuf::Arena* arena) const {
-  UInt32Value* n = new UInt32Value;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<UInt32Value>(arena);
 }
 
 void UInt32Value::Clear() {
@@ -1623,6 +1768,18 @@ bool UInt32Value::IsInitialized() const {
 
 void UInt32Value::Swap(UInt32Value* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    UInt32Value temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void UInt32Value::UnsafeArenaSwap(UInt32Value* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void UInt32Value::InternalSwap(UInt32Value* other) {
@@ -1670,6 +1827,14 @@ BoolValue::BoolValue()
   // @@protoc_insertion_point(constructor:google.protobuf.BoolValue)
 }
 
+BoolValue::BoolValue(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.BoolValue)
+}
+
 void BoolValue::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -1694,10 +1859,20 @@ BoolValue::~BoolValue() {
 }
 
 void BoolValue::SharedDtor() {
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
   if (this != default_instance_) {
   }
 }
 
+void BoolValue::ArenaDtor(void* object) {
+  BoolValue* _this = reinterpret_cast< BoolValue* >(object);
+  (void)_this;
+}
+void BoolValue::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void BoolValue::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -1716,11 +1891,7 @@ const BoolValue& BoolValue::default_instance() {
 BoolValue* BoolValue::default_instance_ = NULL;
 
 BoolValue* BoolValue::New(::google::protobuf::Arena* arena) const {
-  BoolValue* n = new BoolValue;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<BoolValue>(arena);
 }
 
 void BoolValue::Clear() {
@@ -1847,6 +2018,18 @@ bool BoolValue::IsInitialized() const {
 
 void BoolValue::Swap(BoolValue* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    BoolValue temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void BoolValue::UnsafeArenaSwap(BoolValue* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void BoolValue::InternalSwap(BoolValue* other) {
@@ -1894,6 +2077,14 @@ StringValue::StringValue()
   // @@protoc_insertion_point(constructor:google.protobuf.StringValue)
 }
 
+StringValue::StringValue(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.StringValue)
+}
+
 void StringValue::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -1919,11 +2110,21 @@ StringValue::~StringValue() {
 }
 
 void StringValue::SharedDtor() {
-  value_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
+  value_.Destroy(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
   if (this != default_instance_) {
   }
 }
 
+void StringValue::ArenaDtor(void* object) {
+  StringValue* _this = reinterpret_cast< StringValue* >(object);
+  (void)_this;
+}
+void StringValue::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void StringValue::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -1942,15 +2143,11 @@ const StringValue& StringValue::default_instance() {
 StringValue* StringValue::default_instance_ = NULL;
 
 StringValue* StringValue::New(::google::protobuf::Arena* arena) const {
-  StringValue* n = new StringValue;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<StringValue>(arena);
 }
 
 void StringValue::Clear() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 
 bool StringValue::MergePartialFromCodedStream(
@@ -2065,8 +2262,7 @@ void StringValue::MergeFrom(const ::google::protobuf::Message& from) {
 void StringValue::MergeFrom(const StringValue& from) {
   if (GOOGLE_PREDICT_FALSE(&from == this)) MergeFromFail(__LINE__);
   if (from.value().size() > 0) {
-
-    value_.AssignWithDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), from.value_);
+    set_value(from.value());
   }
 }
 
@@ -2089,6 +2285,18 @@ bool StringValue::IsInitialized() const {
 
 void StringValue::Swap(StringValue* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    StringValue temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void StringValue::UnsafeArenaSwap(StringValue* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void StringValue::InternalSwap(StringValue* other) {
@@ -2110,36 +2318,44 @@ void StringValue::InternalSwap(StringValue* other) {
 
 // optional string value = 1;
 void StringValue::clear_value() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
  const ::std::string& StringValue::value() const {
   // @@protoc_insertion_point(field_get:google.protobuf.StringValue.value)
-  return value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Get(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 }
  void StringValue::set_value(const ::std::string& value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set:google.protobuf.StringValue.value)
 }
  void StringValue::set_value(const char* value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value),
+              GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_char:google.protobuf.StringValue.value)
 }
- void StringValue::set_value(const char* value, size_t size) {
+ void StringValue::set_value(const char* value,
+    size_t size) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
-      ::std::string(reinterpret_cast<const char*>(value), size));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(
+      reinterpret_cast<const char*>(value), size), GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_pointer:google.protobuf.StringValue.value)
 }
  ::std::string* StringValue::mutable_value() {
   
   // @@protoc_insertion_point(field_mutable:google.protobuf.StringValue.value)
-  return value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Mutable(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
  ::std::string* StringValue::release_value() {
   
-  return value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Release(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
+}
+ ::std::string* StringValue::unsafe_arena_release_value() {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  
+  return value_.UnsafeArenaRelease(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      GetArenaNoVirtual());
 }
  void StringValue::set_allocated_value(::std::string* value) {
   if (value != NULL) {
@@ -2147,7 +2363,20 @@ void StringValue::clear_value() {
   } else {
     
   }
-  value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.SetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value,
+      GetArenaNoVirtual());
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.StringValue.value)
+}
+ void StringValue::unsafe_arena_set_allocated_value(
+    ::std::string* value) {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  if (value != NULL) {
+    
+  } else {
+    
+  }
+  value_.UnsafeArenaSetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.StringValue.value)
 }
 
@@ -2165,6 +2394,14 @@ BytesValue::BytesValue()
   // @@protoc_insertion_point(constructor:google.protobuf.BytesValue)
 }
 
+BytesValue::BytesValue(::google::protobuf::Arena* arena)
+  : ::google::protobuf::Message(),
+  _internal_metadata_(arena) {
+  SharedCtor();
+  RegisterArenaDtor(arena);
+  // @@protoc_insertion_point(arena_constructor:google.protobuf.BytesValue)
+}
+
 void BytesValue::InitAsDefaultInstance() {
   _is_default_instance_ = true;
 }
@@ -2190,11 +2427,21 @@ BytesValue::~BytesValue() {
 }
 
 void BytesValue::SharedDtor() {
-  value_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  if (GetArenaNoVirtual() != NULL) {
+    return;
+  }
+
+  value_.Destroy(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
   if (this != default_instance_) {
   }
 }
 
+void BytesValue::ArenaDtor(void* object) {
+  BytesValue* _this = reinterpret_cast< BytesValue* >(object);
+  (void)_this;
+}
+void BytesValue::RegisterArenaDtor(::google::protobuf::Arena* arena) {
+}
 void BytesValue::SetCachedSize(int size) const {
   GOOGLE_SAFE_CONCURRENT_WRITES_BEGIN();
   _cached_size_ = size;
@@ -2213,15 +2460,11 @@ const BytesValue& BytesValue::default_instance() {
 BytesValue* BytesValue::default_instance_ = NULL;
 
 BytesValue* BytesValue::New(::google::protobuf::Arena* arena) const {
-  BytesValue* n = new BytesValue;
-  if (arena != NULL) {
-    arena->Own(n);
-  }
-  return n;
+  return ::google::protobuf::Arena::CreateMessage<BytesValue>(arena);
 }
 
 void BytesValue::Clear() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 
 bool BytesValue::MergePartialFromCodedStream(
@@ -2324,8 +2567,7 @@ void BytesValue::MergeFrom(const ::google::protobuf::Message& from) {
 void BytesValue::MergeFrom(const BytesValue& from) {
   if (GOOGLE_PREDICT_FALSE(&from == this)) MergeFromFail(__LINE__);
   if (from.value().size() > 0) {
-
-    value_.AssignWithDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), from.value_);
+    set_value(from.value());
   }
 }
 
@@ -2348,6 +2590,18 @@ bool BytesValue::IsInitialized() const {
 
 void BytesValue::Swap(BytesValue* other) {
   if (other == this) return;
+  if (GetArenaNoVirtual() == other->GetArenaNoVirtual()) {
+    InternalSwap(other);
+  } else {
+    BytesValue temp;
+    temp.MergeFrom(*this);
+    CopyFrom(*other);
+    other->CopyFrom(temp);
+  }
+}
+void BytesValue::UnsafeArenaSwap(BytesValue* other) {
+  if (other == this) return;
+  GOOGLE_DCHECK(GetArenaNoVirtual() == other->GetArenaNoVirtual());
   InternalSwap(other);
 }
 void BytesValue::InternalSwap(BytesValue* other) {
@@ -2369,36 +2623,44 @@ void BytesValue::InternalSwap(BytesValue* other) {
 
 // optional bytes value = 1;
 void BytesValue::clear_value() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
  const ::std::string& BytesValue::value() const {
   // @@protoc_insertion_point(field_get:google.protobuf.BytesValue.value)
-  return value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Get(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 }
  void BytesValue::set_value(const ::std::string& value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set:google.protobuf.BytesValue.value)
 }
  void BytesValue::set_value(const char* value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value),
+              GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_char:google.protobuf.BytesValue.value)
 }
- void BytesValue::set_value(const void* value, size_t size) {
+ void BytesValue::set_value(const void* value,
+    size_t size) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
-      ::std::string(reinterpret_cast<const char*>(value), size));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(
+      reinterpret_cast<const char*>(value), size), GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_pointer:google.protobuf.BytesValue.value)
 }
  ::std::string* BytesValue::mutable_value() {
   
   // @@protoc_insertion_point(field_mutable:google.protobuf.BytesValue.value)
-  return value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Mutable(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
  ::std::string* BytesValue::release_value() {
   
-  return value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Release(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
+}
+ ::std::string* BytesValue::unsafe_arena_release_value() {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  
+  return value_.UnsafeArenaRelease(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      GetArenaNoVirtual());
 }
  void BytesValue::set_allocated_value(::std::string* value) {
   if (value != NULL) {
@@ -2406,7 +2668,20 @@ void BytesValue::clear_value() {
   } else {
     
   }
-  value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.SetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value,
+      GetArenaNoVirtual());
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.BytesValue.value)
+}
+ void BytesValue::unsafe_arena_set_allocated_value(
+    ::std::string* value) {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  if (value != NULL) {
+    
+  } else {
+    
+  }
+  value_.UnsafeArenaSetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.BytesValue.value)
 }
 
diff --git a/src/google/protobuf/wrappers.pb.h b/src/google/protobuf/wrappers.pb.h
index 15bcc7a2..7dca938c 100644
--- a/src/google/protobuf/wrappers.pb.h
+++ b/src/google/protobuf/wrappers.pb.h
@@ -61,9 +61,14 @@ class LIBPROTOBUF_EXPORT DoubleValue : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const DoubleValue& default_instance();
 
+  void UnsafeArenaSwap(DoubleValue* other);
   void Swap(DoubleValue* other);
 
   // implements Message ----------------------------------------------
@@ -90,6 +95,11 @@ class LIBPROTOBUF_EXPORT DoubleValue : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(DoubleValue* other);
+  protected:
+  explicit DoubleValue(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -115,6 +125,9 @@ class LIBPROTOBUF_EXPORT DoubleValue : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   double value_;
   mutable int _cached_size_;
@@ -139,9 +152,14 @@ class LIBPROTOBUF_EXPORT FloatValue : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const FloatValue& default_instance();
 
+  void UnsafeArenaSwap(FloatValue* other);
   void Swap(FloatValue* other);
 
   // implements Message ----------------------------------------------
@@ -168,6 +186,11 @@ class LIBPROTOBUF_EXPORT FloatValue : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(FloatValue* other);
+  protected:
+  explicit FloatValue(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -193,6 +216,9 @@ class LIBPROTOBUF_EXPORT FloatValue : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   float value_;
   mutable int _cached_size_;
@@ -217,9 +243,14 @@ class LIBPROTOBUF_EXPORT Int64Value : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const Int64Value& default_instance();
 
+  void UnsafeArenaSwap(Int64Value* other);
   void Swap(Int64Value* other);
 
   // implements Message ----------------------------------------------
@@ -246,6 +277,11 @@ class LIBPROTOBUF_EXPORT Int64Value : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(Int64Value* other);
+  protected:
+  explicit Int64Value(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -271,6 +307,9 @@ class LIBPROTOBUF_EXPORT Int64Value : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::int64 value_;
   mutable int _cached_size_;
@@ -295,9 +334,14 @@ class LIBPROTOBUF_EXPORT UInt64Value : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const UInt64Value& default_instance();
 
+  void UnsafeArenaSwap(UInt64Value* other);
   void Swap(UInt64Value* other);
 
   // implements Message ----------------------------------------------
@@ -324,6 +368,11 @@ class LIBPROTOBUF_EXPORT UInt64Value : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(UInt64Value* other);
+  protected:
+  explicit UInt64Value(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -349,6 +398,9 @@ class LIBPROTOBUF_EXPORT UInt64Value : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::uint64 value_;
   mutable int _cached_size_;
@@ -373,9 +425,14 @@ class LIBPROTOBUF_EXPORT Int32Value : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const Int32Value& default_instance();
 
+  void UnsafeArenaSwap(Int32Value* other);
   void Swap(Int32Value* other);
 
   // implements Message ----------------------------------------------
@@ -402,6 +459,11 @@ class LIBPROTOBUF_EXPORT Int32Value : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(Int32Value* other);
+  protected:
+  explicit Int32Value(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -427,6 +489,9 @@ class LIBPROTOBUF_EXPORT Int32Value : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::int32 value_;
   mutable int _cached_size_;
@@ -451,9 +516,14 @@ class LIBPROTOBUF_EXPORT UInt32Value : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const UInt32Value& default_instance();
 
+  void UnsafeArenaSwap(UInt32Value* other);
   void Swap(UInt32Value* other);
 
   // implements Message ----------------------------------------------
@@ -480,6 +550,11 @@ class LIBPROTOBUF_EXPORT UInt32Value : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(UInt32Value* other);
+  protected:
+  explicit UInt32Value(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -505,6 +580,9 @@ class LIBPROTOBUF_EXPORT UInt32Value : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::uint32 value_;
   mutable int _cached_size_;
@@ -529,9 +607,14 @@ class LIBPROTOBUF_EXPORT BoolValue : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const BoolValue& default_instance();
 
+  void UnsafeArenaSwap(BoolValue* other);
   void Swap(BoolValue* other);
 
   // implements Message ----------------------------------------------
@@ -558,6 +641,11 @@ class LIBPROTOBUF_EXPORT BoolValue : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(BoolValue* other);
+  protected:
+  explicit BoolValue(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -583,6 +671,9 @@ class LIBPROTOBUF_EXPORT BoolValue : public ::google::protobuf::Message {
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   bool value_;
   mutable int _cached_size_;
@@ -607,9 +698,14 @@ class LIBPROTOBUF_EXPORT StringValue : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const StringValue& default_instance();
 
+  void UnsafeArenaSwap(StringValue* other);
   void Swap(StringValue* other);
 
   // implements Message ----------------------------------------------
@@ -636,6 +732,11 @@ class LIBPROTOBUF_EXPORT StringValue : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(StringValue* other);
+  protected:
+  explicit StringValue(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -661,11 +762,17 @@ class LIBPROTOBUF_EXPORT StringValue : public ::google::protobuf::Message {
   ::std::string* mutable_value();
   ::std::string* release_value();
   void set_allocated_value(::std::string* value);
+  ::std::string* unsafe_arena_release_value();
+  void unsafe_arena_set_allocated_value(
+      ::std::string* value);
 
   // @@protoc_insertion_point(class_scope:google.protobuf.StringValue)
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::internal::ArenaStringPtr value_;
   mutable int _cached_size_;
@@ -690,9 +797,14 @@ class LIBPROTOBUF_EXPORT BytesValue : public ::google::protobuf::Message {
     return *this;
   }
 
+  inline ::google::protobuf::Arena* GetArena() const { return GetArenaNoVirtual(); }
+  inline void* GetMaybeArenaPointer() const {
+    return MaybeArenaPtr();
+  }
   static const ::google::protobuf::Descriptor* descriptor();
   static const BytesValue& default_instance();
 
+  void UnsafeArenaSwap(BytesValue* other);
   void Swap(BytesValue* other);
 
   // implements Message ----------------------------------------------
@@ -719,6 +831,11 @@ class LIBPROTOBUF_EXPORT BytesValue : public ::google::protobuf::Message {
   void SharedDtor();
   void SetCachedSize(int size) const;
   void InternalSwap(BytesValue* other);
+  protected:
+  explicit BytesValue(::google::protobuf::Arena* arena);
+  private:
+  static void ArenaDtor(void* object);
+  inline void RegisterArenaDtor(::google::protobuf::Arena* arena);
   private:
   inline ::google::protobuf::Arena* GetArenaNoVirtual() const {
     return _internal_metadata_.arena();
@@ -744,11 +861,17 @@ class LIBPROTOBUF_EXPORT BytesValue : public ::google::protobuf::Message {
   ::std::string* mutable_value();
   ::std::string* release_value();
   void set_allocated_value(::std::string* value);
+  ::std::string* unsafe_arena_release_value();
+  void unsafe_arena_set_allocated_value(
+      ::std::string* value);
 
   // @@protoc_insertion_point(class_scope:google.protobuf.BytesValue)
  private:
 
   ::google::protobuf::internal::InternalMetadataWithArena _internal_metadata_;
+  friend class ::google::protobuf::Arena;
+  typedef void InternalArenaConstructable_;
+  typedef void DestructorSkippable_;
   bool _is_default_instance_;
   ::google::protobuf::internal::ArenaStringPtr value_;
   mutable int _cached_size_;
@@ -895,36 +1018,44 @@ inline void BoolValue::set_value(bool value) {
 
 // optional string value = 1;
 inline void StringValue::clear_value() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 inline const ::std::string& StringValue::value() const {
   // @@protoc_insertion_point(field_get:google.protobuf.StringValue.value)
-  return value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Get(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 }
 inline void StringValue::set_value(const ::std::string& value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set:google.protobuf.StringValue.value)
 }
 inline void StringValue::set_value(const char* value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value),
+              GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_char:google.protobuf.StringValue.value)
 }
-inline void StringValue::set_value(const char* value, size_t size) {
+inline void StringValue::set_value(const char* value,
+    size_t size) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
-      ::std::string(reinterpret_cast<const char*>(value), size));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(
+      reinterpret_cast<const char*>(value), size), GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_pointer:google.protobuf.StringValue.value)
 }
 inline ::std::string* StringValue::mutable_value() {
   
   // @@protoc_insertion_point(field_mutable:google.protobuf.StringValue.value)
-  return value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Mutable(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 inline ::std::string* StringValue::release_value() {
   
-  return value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Release(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
+}
+inline ::std::string* StringValue::unsafe_arena_release_value() {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  
+  return value_.UnsafeArenaRelease(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      GetArenaNoVirtual());
 }
 inline void StringValue::set_allocated_value(::std::string* value) {
   if (value != NULL) {
@@ -932,7 +1063,20 @@ inline void StringValue::set_allocated_value(::std::string* value) {
   } else {
     
   }
-  value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.SetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value,
+      GetArenaNoVirtual());
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.StringValue.value)
+}
+inline void StringValue::unsafe_arena_set_allocated_value(
+    ::std::string* value) {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  if (value != NULL) {
+    
+  } else {
+    
+  }
+  value_.UnsafeArenaSetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.StringValue.value)
 }
 
@@ -942,36 +1086,44 @@ inline void StringValue::set_allocated_value(::std::string* value) {
 
 // optional bytes value = 1;
 inline void BytesValue::clear_value() {
-  value_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  value_.ClearToEmpty(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 inline const ::std::string& BytesValue::value() const {
   // @@protoc_insertion_point(field_get:google.protobuf.BytesValue.value)
-  return value_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Get(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
 }
 inline void BytesValue::set_value(const ::std::string& value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set:google.protobuf.BytesValue.value)
 }
 inline void BytesValue::set_value(const char* value) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value),
+              GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_char:google.protobuf.BytesValue.value)
 }
-inline void BytesValue::set_value(const void* value, size_t size) {
+inline void BytesValue::set_value(const void* value,
+    size_t size) {
   
-  value_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
-      ::std::string(reinterpret_cast<const char*>(value), size));
+  value_.Set(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(
+      reinterpret_cast<const char*>(value), size), GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_pointer:google.protobuf.BytesValue.value)
 }
 inline ::std::string* BytesValue::mutable_value() {
   
   // @@protoc_insertion_point(field_mutable:google.protobuf.BytesValue.value)
-  return value_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Mutable(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
 }
 inline ::std::string* BytesValue::release_value() {
   
-  return value_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  return value_.Release(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), GetArenaNoVirtual());
+}
+inline ::std::string* BytesValue::unsafe_arena_release_value() {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  
+  return value_.UnsafeArenaRelease(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      GetArenaNoVirtual());
 }
 inline void BytesValue::set_allocated_value(::std::string* value) {
   if (value != NULL) {
@@ -979,7 +1131,20 @@ inline void BytesValue::set_allocated_value(::std::string* value) {
   } else {
     
   }
-  value_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  value_.SetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value,
+      GetArenaNoVirtual());
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.BytesValue.value)
+}
+inline void BytesValue::unsafe_arena_set_allocated_value(
+    ::std::string* value) {
+  GOOGLE_DCHECK(GetArenaNoVirtual() != NULL);
+  if (value != NULL) {
+    
+  } else {
+    
+  }
+  value_.UnsafeArenaSetAllocated(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      value, GetArenaNoVirtual());
   // @@protoc_insertion_point(field_set_allocated:google.protobuf.BytesValue.value)
 }
 
diff --git a/src/google/protobuf/wrappers.proto b/src/google/protobuf/wrappers.proto
index a1d6e446..040d8a24 100644
--- a/src/google/protobuf/wrappers.proto
+++ b/src/google/protobuf/wrappers.proto
@@ -37,11 +37,12 @@ syntax = "proto3";
 
 package google.protobuf;
 
-option java_generate_equals_and_hash = true;
-option java_multiple_files = true;
-option java_outer_classname = "WrappersProto";
-option java_package = "com.google.protobuf";
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
+option cc_enable_arenas = true;
+option java_package = "com.google.protobuf";
+option java_outer_classname = "WrappersProto";
+option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
 // Wrapper message for `double`.