Restructuring protobuf to multiple modules

protobuf/java will become a parent pom that will contain two modules:

core - contains all of the code for the protobuf-java artifact
util - contains all of the code for the protobuf-java-util artifact

Also cleaned up various Maven warnings.

1 files changed, 889 insertions, 0 deletions

diff --git a/java/core/src/main/java/com/google/protobuf/FieldSet.java b/java/core/src/main/java/com/google/protobuf/FieldSet.java
new file mode 100644
index 00000000..47924b65
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/FieldSet.java
@@ -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.
+
+package com.google.protobuf;
+
+import com.google.protobuf.LazyField.LazyIterator;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A class which represents an arbitrary set of fields of some message type.
+ * This is used to implement {@link DynamicMessage}, and also to represent
+ * extensions in {@link GeneratedMessage}.  This class is package-private,
+ * since outside users should probably be using {@link DynamicMessage}.
+ *
+ * @author kenton@google.com Kenton Varda
+ */
+final class FieldSet<FieldDescriptorType extends
+      FieldSet.FieldDescriptorLite<FieldDescriptorType>> {
+  /**
+   * Interface for a FieldDescriptor or lite extension descriptor.  This
+   * prevents FieldSet from depending on {@link Descriptors.FieldDescriptor}.
+   */
+  public interface FieldDescriptorLite<T extends FieldDescriptorLite<T>>
+      extends Comparable<T> {
+    int getNumber();
+    WireFormat.FieldType getLiteType();
+    WireFormat.JavaType getLiteJavaType();
+    boolean isRepeated();
+    boolean isPacked();
+    Internal.EnumLiteMap<?> getEnumType();
+
+    // If getLiteJavaType() == MESSAGE, this merges a message object of the
+    // type into a builder of the type.  Returns {@code to}.
+    MessageLite.Builder internalMergeFrom(
+        MessageLite.Builder to, MessageLite from);
+  }
+
+  private final SmallSortedMap<FieldDescriptorType, Object> fields;
+  private boolean isImmutable;
+  private boolean hasLazyField = false;
+
+  /** Construct a new FieldSet. */
+  private FieldSet() {
+    this.fields = SmallSortedMap.newFieldMap(16);
+  }
+
+  /**
+   * Construct an empty FieldSet.  This is only used to initialize
+   * DEFAULT_INSTANCE.
+   */
+  private FieldSet(final boolean dummy) {
+    this.fields = SmallSortedMap.newFieldMap(0);
+    makeImmutable();
+  }
+
+  /** Construct a new FieldSet. */
+  public static <T extends FieldSet.FieldDescriptorLite<T>>
+      FieldSet<T> newFieldSet() {
+    return new FieldSet<T>();
+  }
+
+  /** Get an immutable empty FieldSet. */
+  @SuppressWarnings("unchecked")
+  public static <T extends FieldSet.FieldDescriptorLite<T>>
+      FieldSet<T> emptySet() {
+    return DEFAULT_INSTANCE;
+  }
+  @SuppressWarnings("rawtypes")
+  private static final FieldSet DEFAULT_INSTANCE = new FieldSet(true);
+
+  /** Make this FieldSet immutable from this point forward. */
+  @SuppressWarnings("unchecked")
+  public void makeImmutable() {
+    if (isImmutable) {
+      return;
+    }
+    fields.makeImmutable();
+    isImmutable = true;
+  }
+
+  /**
+   * Returns whether the FieldSet is immutable. This is true if it is the
+   * {@link #emptySet} or if {@link #makeImmutable} were called.
+   *
+   * @return whether the FieldSet is immutable.
+   */
+  public boolean isImmutable() {
+    return isImmutable;
+  }
+
+  /**
+   * Clones the FieldSet. The returned FieldSet will be mutable even if the
+   * original FieldSet was immutable.
+   *
+   * @return the newly cloned FieldSet
+   */
+  @Override
+  public FieldSet<FieldDescriptorType> clone() {
+    // We can't just call fields.clone because List objects in the map
+    // should not be shared.
+    FieldSet<FieldDescriptorType> clone = FieldSet.newFieldSet();
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      Map.Entry<FieldDescriptorType, Object> entry = fields.getArrayEntryAt(i);
+      FieldDescriptorType descriptor = entry.getKey();
+      clone.setField(descriptor, entry.getValue());
+    }
+    for (Map.Entry<FieldDescriptorType, Object> entry :
+             fields.getOverflowEntries()) {
+      FieldDescriptorType descriptor = entry.getKey();
+      clone.setField(descriptor, entry.getValue());
+    }
+    clone.hasLazyField = hasLazyField;
+    return clone;
+  }
+
+
+  // =================================================================
+
+  /** See {@link Message.Builder#clear()}. */
+  public void clear() {
+    fields.clear();
+    hasLazyField = false;
+  }
+
+  /**
+   * Get a simple map containing all the fields.
+   */
+  public Map<FieldDescriptorType, Object> getAllFields() {
+    if (hasLazyField) {
+      SmallSortedMap<FieldDescriptorType, Object> result =
+          SmallSortedMap.newFieldMap(16);
+      for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+        cloneFieldEntry(result, fields.getArrayEntryAt(i));
+      }
+      for (Map.Entry<FieldDescriptorType, Object> entry :
+          fields.getOverflowEntries()) {
+        cloneFieldEntry(result, entry);
+      }
+      if (fields.isImmutable()) {
+        result.makeImmutable();
+      }
+      return result;
+    }
+    return fields.isImmutable() ? fields : Collections.unmodifiableMap(fields);
+  }
+
+  private void cloneFieldEntry(Map<FieldDescriptorType, Object> map,
+      Map.Entry<FieldDescriptorType, Object> entry) {
+    FieldDescriptorType key = entry.getKey();
+    Object value = entry.getValue();
+    if (value instanceof LazyField) {
+      map.put(key, ((LazyField) value).getValue());
+    } else {
+      map.put(key, value);
+    }
+  }
+
+  /**
+   * Get an iterator to the field map. This iterator should not be leaked out
+   * of the protobuf library as it is not protected from mutation when fields
+   * is not immutable.
+   */
+  public Iterator<Map.Entry<FieldDescriptorType, Object>> iterator() {
+    if (hasLazyField) {
+      return new LazyIterator<FieldDescriptorType>(
+          fields.entrySet().iterator());
+    }
+    return fields.entrySet().iterator();
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message#hasField(Descriptors.FieldDescriptor)}.
+   */
+  public boolean hasField(final FieldDescriptorType descriptor) {
+    if (descriptor.isRepeated()) {
+      throw new IllegalArgumentException(
+        "hasField() can only be called on non-repeated fields.");
+    }
+
+    return fields.get(descriptor) != null;
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message#getField(Descriptors.FieldDescriptor)}.  This method
+   * returns {@code null} if the field is not set; in this case it is up
+   * to the caller to fetch the field's default value.
+   */
+  public Object getField(final FieldDescriptorType descriptor) {
+    Object o = fields.get(descriptor);
+    if (o instanceof LazyField) {
+      return ((LazyField) o).getValue();
+    }
+    return o;
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message.Builder#setField(Descriptors.FieldDescriptor,Object)}.
+   */
+  @SuppressWarnings({"unchecked", "rawtypes"})
+  public void setField(final FieldDescriptorType descriptor,
+                       Object value) {
+    if (descriptor.isRepeated()) {
+      if (!(value instanceof List)) {
+        throw new IllegalArgumentException(
+          "Wrong object type used with protocol message reflection.");
+      }
+
+      // Wrap the contents in a new list so that the caller cannot change
+      // the list's contents after setting it.
+      final List newList = new ArrayList();
+      newList.addAll((List) value);
+      for (final Object element : newList) {
+        verifyType(descriptor.getLiteType(), element);
+      }
+      value = newList;
+    } else {
+      verifyType(descriptor.getLiteType(), value);
+    }
+
+    if (value instanceof LazyField) {
+      hasLazyField = true;
+    }
+    fields.put(descriptor, value);
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message.Builder#clearField(Descriptors.FieldDescriptor)}.
+   */
+  public void clearField(final FieldDescriptorType descriptor) {
+    fields.remove(descriptor);
+    if (fields.isEmpty()) {
+      hasLazyField = false;
+    }
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message#getRepeatedFieldCount(Descriptors.FieldDescriptor)}.
+   */
+  public int getRepeatedFieldCount(final FieldDescriptorType descriptor) {
+    if (!descriptor.isRepeated()) {
+      throw new IllegalArgumentException(
+        "getRepeatedField() can only be called on repeated fields.");
+    }
+
+    final Object value = getField(descriptor);
+    if (value == null) {
+      return 0;
+    } else {
+      return ((List<?>) value).size();
+    }
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message#getRepeatedField(Descriptors.FieldDescriptor,int)}.
+   */
+  public Object getRepeatedField(final FieldDescriptorType descriptor,
+                                 final int index) {
+    if (!descriptor.isRepeated()) {
+      throw new IllegalArgumentException(
+        "getRepeatedField() can only be called on repeated fields.");
+    }
+
+    final Object value = getField(descriptor);
+
+    if (value == null) {
+      throw new IndexOutOfBoundsException();
+    } else {
+      return ((List<?>) value).get(index);
+    }
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message.Builder#setRepeatedField(Descriptors.FieldDescriptor,int,Object)}.
+   */
+  @SuppressWarnings("unchecked")
+  public void setRepeatedField(final FieldDescriptorType descriptor,
+                               final int index,
+                               final Object value) {
+    if (!descriptor.isRepeated()) {
+      throw new IllegalArgumentException(
+        "getRepeatedField() can only be called on repeated fields.");
+    }
+
+    final Object list = getField(descriptor);
+    if (list == null) {
+      throw new IndexOutOfBoundsException();
+    }
+
+    verifyType(descriptor.getLiteType(), value);
+    ((List<Object>) list).set(index, value);
+  }
+
+  /**
+   * Useful for implementing
+   * {@link Message.Builder#addRepeatedField(Descriptors.FieldDescriptor,Object)}.
+   */
+  @SuppressWarnings("unchecked")
+  public void addRepeatedField(final FieldDescriptorType descriptor,
+                               final Object value) {
+    if (!descriptor.isRepeated()) {
+      throw new IllegalArgumentException(
+        "addRepeatedField() can only be called on repeated fields.");
+    }
+
+    verifyType(descriptor.getLiteType(), value);
+
+    final Object existingValue = getField(descriptor);
+    List<Object> list;
+    if (existingValue == null) {
+      list = new ArrayList<Object>();
+      fields.put(descriptor, list);
+    } else {
+      list = (List<Object>) existingValue;
+    }
+
+    list.add(value);
+  }
+
+  /**
+   * Verifies that the given object is of the correct type to be a valid
+   * value for the given field.  (For repeated fields, this checks if the
+   * object is the right type to be one element of the field.)
+   *
+   * @throws IllegalArgumentException The value is not of the right type.
+   */
+  private static void verifyType(final WireFormat.FieldType type,
+                                 final Object value) {
+    if (value == null) {
+      throw new NullPointerException();
+    }
+
+    boolean isValid = false;
+    switch (type.getJavaType()) {
+      case INT:          isValid = value instanceof Integer   ; break;
+      case LONG:         isValid = value instanceof Long      ; break;
+      case FLOAT:        isValid = value instanceof Float     ; break;
+      case DOUBLE:       isValid = value instanceof Double    ; break;
+      case BOOLEAN:      isValid = value instanceof Boolean   ; break;
+      case STRING:       isValid = value instanceof String    ; break;
+      case BYTE_STRING:
+        isValid = value instanceof ByteString || value instanceof byte[];
+        break;
+      case ENUM:
+        // TODO(kenton):  Caller must do type checking here, I guess.
+        isValid =
+            (value instanceof Integer || value instanceof Internal.EnumLite);
+        break;
+      case MESSAGE:
+        // TODO(kenton):  Caller must do type checking here, I guess.
+        isValid =
+            (value instanceof MessageLite) || (value instanceof LazyField);
+        break;
+    }
+
+    if (!isValid) {
+      // TODO(kenton):  When chaining calls to setField(), it can be hard to
+      //   tell from the stack trace which exact call failed, since the whole
+      //   chain is considered one line of code.  It would be nice to print
+      //   more information here, e.g. naming the field.  We used to do that.
+      //   But we can't now that FieldSet doesn't use descriptors.  Maybe this
+      //   isn't a big deal, though, since it would only really apply when using
+      //   reflection and generally people don't chain reflection setters.
+      throw new IllegalArgumentException(
+        "Wrong object type used with protocol message reflection.");
+    }
+  }
+
+  // =================================================================
+  // Parsing and serialization
+
+  /**
+   * See {@link Message#isInitialized()}.  Note:  Since {@code FieldSet}
+   * itself does not have any way of knowing about required fields that
+   * aren't actually present in the set, it is up to the caller to check
+   * that all required fields are present.
+   */
+  public boolean isInitialized() {
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      if (!isInitialized(fields.getArrayEntryAt(i))) {
+        return false;
+      }
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+             fields.getOverflowEntries()) {
+      if (!isInitialized(entry)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @SuppressWarnings("unchecked")
+  private boolean isInitialized(
+      final Map.Entry<FieldDescriptorType, Object> entry) {
+    final FieldDescriptorType descriptor = entry.getKey();
+    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE) {
+      if (descriptor.isRepeated()) {
+        for (final MessageLite element:
+                 (List<MessageLite>) entry.getValue()) {
+          if (!element.isInitialized()) {
+            return false;
+          }
+        }
+      } else {
+        Object value = entry.getValue();
+        if (value instanceof MessageLite) {
+          if (!((MessageLite) value).isInitialized()) {
+            return false;
+          }
+        } else if (value instanceof LazyField) {
+          return true;
+        } else {
+          throw new IllegalArgumentException(
+              "Wrong object type used with protocol message reflection.");
+        }
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Given a field type, return the wire type.
+   *
+   * @returns One of the {@code WIRETYPE_} constants defined in
+   *          {@link WireFormat}.
+   */
+  static int getWireFormatForFieldType(final WireFormat.FieldType type,
+                                       boolean isPacked) {
+    if (isPacked) {
+      return WireFormat.WIRETYPE_LENGTH_DELIMITED;
+    } else {
+      return type.getWireType();
+    }
+  }
+
+  /**
+   * Like {@link Message.Builder#mergeFrom(Message)}, but merges from another 
+   * {@link FieldSet}.
+   */
+  public void mergeFrom(final FieldSet<FieldDescriptorType> other) {
+    for (int i = 0; i < other.fields.getNumArrayEntries(); i++) {
+      mergeFromField(other.fields.getArrayEntryAt(i));
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+             other.fields.getOverflowEntries()) {
+      mergeFromField(entry);
+    }
+  }
+
+  private Object cloneIfMutable(Object value) {
+    if (value instanceof byte[]) {
+      byte[] bytes = (byte[]) value;
+      byte[] copy = new byte[bytes.length];
+      System.arraycopy(bytes, 0, copy, 0, bytes.length);
+      return copy;
+    } else {
+      return value;
+    }
+  }
+
+  @SuppressWarnings({"unchecked", "rawtypes"})
+  private void mergeFromField(
+      final Map.Entry<FieldDescriptorType, Object> entry) {
+    final FieldDescriptorType descriptor = entry.getKey();
+    Object otherValue = entry.getValue();
+    if (otherValue instanceof LazyField) {
+      otherValue = ((LazyField) otherValue).getValue();
+    }
+
+    if (descriptor.isRepeated()) {
+      Object value = getField(descriptor);
+      if (value == null) {
+        value = new ArrayList();
+      }
+      for (Object element : (List) otherValue) {
+        ((List) value).add(cloneIfMutable(element));
+      }
+      fields.put(descriptor, value);
+    } else if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE) {
+      Object value = getField(descriptor);
+      if (value == null) {
+        fields.put(descriptor, cloneIfMutable(otherValue));
+      } else {
+        // Merge the messages.
+          value = descriptor.internalMergeFrom(
+                ((MessageLite) value).toBuilder(), (MessageLite) otherValue)
+                .build();
+
+        fields.put(descriptor, value);
+      }
+    } else {
+      fields.put(descriptor, cloneIfMutable(otherValue));
+    }
+  }
+
+  // TODO(kenton):  Move static parsing and serialization methods into some
+  //   other class.  Probably WireFormat.
+
+  /**
+   * Read a field of any primitive type for immutable messages from a
+   * CodedInputStream. Enums, groups, and embedded messages are not handled by
+   * this method.
+   *
+   * @param input The stream from which to read.
+   * @param type Declared type of the field.
+   * @param checkUtf8 When true, check that the input is valid utf8.
+   * @return An object representing the field's value, of the exact
+   *         type which would be returned by
+   *         {@link Message#getField(Descriptors.FieldDescriptor)} for
+   *         this field.
+   */
+  public static Object readPrimitiveField(
+      CodedInputStream input,
+      final WireFormat.FieldType type,
+      boolean checkUtf8) throws IOException {
+    if (checkUtf8) {
+      return WireFormat.readPrimitiveField(input, type,
+          WireFormat.Utf8Validation.STRICT);
+    } else {
+      return WireFormat.readPrimitiveField(input, type,
+          WireFormat.Utf8Validation.LOOSE);
+    }
+  }
+
+
+  /** See {@link Message#writeTo(CodedOutputStream)}. */
+  public void writeTo(final CodedOutputStream output)
+                      throws IOException {
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      final Map.Entry<FieldDescriptorType, Object> entry =
+          fields.getArrayEntryAt(i);
+      writeField(entry.getKey(), entry.getValue(), output);
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+         fields.getOverflowEntries()) {
+      writeField(entry.getKey(), entry.getValue(), output);
+    }
+  }
+
+  /**
+   * Like {@link #writeTo} but uses MessageSet wire format.
+   */
+  public void writeMessageSetTo(final CodedOutputStream output)
+                                throws IOException {
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      writeMessageSetTo(fields.getArrayEntryAt(i), output);
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+             fields.getOverflowEntries()) {
+      writeMessageSetTo(entry, output);
+    }
+  }
+
+  private void writeMessageSetTo(
+      final Map.Entry<FieldDescriptorType, Object> entry,
+      final CodedOutputStream output) throws IOException {
+    final FieldDescriptorType descriptor = entry.getKey();
+    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE &&
+        !descriptor.isRepeated() && !descriptor.isPacked()) {
+      Object value = entry.getValue();
+      if (value instanceof LazyField) {
+        value = ((LazyField) value).getValue();
+      }
+      output.writeMessageSetExtension(entry.getKey().getNumber(),
+                                      (MessageLite) value);
+    } else {
+      writeField(descriptor, entry.getValue(), output);
+    }
+  }
+
+  /**
+   * Write a single tag-value pair to the stream.
+   *
+   * @param output The output stream.
+   * @param type   The field's type.
+   * @param number The field's number.
+   * @param value  Object representing the field's value.  Must be of the exact
+   *               type which would be returned by
+   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
+   *               this field.
+   */
+  private static void writeElement(final CodedOutputStream output,
+                                   final WireFormat.FieldType type,
+                                   final int number,
+                                   final Object value) throws IOException {
+    // Special case for groups, which need a start and end tag; other fields
+    // can just use writeTag() and writeFieldNoTag().
+    if (type == WireFormat.FieldType.GROUP) {
+        output.writeGroup(number, (MessageLite) value);
+    } else {
+      output.writeTag(number, getWireFormatForFieldType(type, false));
+      writeElementNoTag(output, type, value);
+    }
+  }
+
+  /**
+   * Write a field of arbitrary type, without its tag, to the stream.
+   *
+   * @param output The output stream.
+   * @param type The field's type.
+   * @param value  Object representing the field's value.  Must be of the exact
+   *               type which would be returned by
+   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
+   *               this field.
+   */
+  static void writeElementNoTag(
+      final CodedOutputStream output,
+      final WireFormat.FieldType type,
+      final Object value) throws IOException {
+    switch (type) {
+      case DOUBLE  : output.writeDoubleNoTag  ((Double     ) value); break;
+      case FLOAT   : output.writeFloatNoTag   ((Float      ) value); break;
+      case INT64   : output.writeInt64NoTag   ((Long       ) value); break;
+      case UINT64  : output.writeUInt64NoTag  ((Long       ) value); break;
+      case INT32   : output.writeInt32NoTag   ((Integer    ) value); break;
+      case FIXED64 : output.writeFixed64NoTag ((Long       ) value); break;
+      case FIXED32 : output.writeFixed32NoTag ((Integer    ) value); break;
+      case BOOL    : output.writeBoolNoTag    ((Boolean    ) value); break;
+      case GROUP   : output.writeGroupNoTag   ((MessageLite) value); break;
+      case MESSAGE : output.writeMessageNoTag ((MessageLite) value); break;
+      case STRING:
+        if (value instanceof ByteString) {
+          output.writeBytesNoTag((ByteString) value);
+        } else {
+          output.writeStringNoTag((String) value);
+        }
+        break;
+      case BYTES:
+        if (value instanceof ByteString) {
+          output.writeBytesNoTag((ByteString) value);
+        } else {
+          output.writeByteArrayNoTag((byte[]) value);
+        }
+        break;
+      case UINT32  : output.writeUInt32NoTag  ((Integer    ) value); break;
+      case SFIXED32: output.writeSFixed32NoTag((Integer    ) value); break;
+      case SFIXED64: output.writeSFixed64NoTag((Long       ) value); break;
+      case SINT32  : output.writeSInt32NoTag  ((Integer    ) value); break;
+      case SINT64  : output.writeSInt64NoTag  ((Long       ) value); break;
+
+      case ENUM:
+        if (value instanceof Internal.EnumLite) {
+          output.writeEnumNoTag(((Internal.EnumLite) value).getNumber());
+        } else {
+          output.writeEnumNoTag(((Integer) value).intValue());
+        }
+        break;
+    }
+  }
+
+  /** Write a single field. */
+  public static void writeField(final FieldDescriptorLite<?> descriptor,
+                                final Object value,
+                                final CodedOutputStream output)
+                                throws IOException {
+    WireFormat.FieldType type = descriptor.getLiteType();
+    int number = descriptor.getNumber();
+    if (descriptor.isRepeated()) {
+      final List<?> valueList = (List<?>)value;
+      if (descriptor.isPacked()) {
+        output.writeTag(number, WireFormat.WIRETYPE_LENGTH_DELIMITED);
+        // Compute the total data size so the length can be written.
+        int dataSize = 0;
+        for (final Object element : valueList) {
+          dataSize += computeElementSizeNoTag(type, element);
+        }
+        output.writeRawVarint32(dataSize);
+        // Write the data itself, without any tags.
+        for (final Object element : valueList) {
+          writeElementNoTag(output, type, element);
+        }
+      } else {
+        for (final Object element : valueList) {
+          writeElement(output, type, number, element);
+        }
+      }
+    } else {
+      if (value instanceof LazyField) {
+        writeElement(output, type, number, ((LazyField) value).getValue());
+      } else {
+        writeElement(output, type, number, value);
+      }
+    }
+  }
+
+  /**
+   * See {@link Message#getSerializedSize()}.  It's up to the caller to cache
+   * the resulting size if desired.
+   */
+  public int getSerializedSize() {
+    int size = 0;
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      final Map.Entry<FieldDescriptorType, Object> entry =
+          fields.getArrayEntryAt(i);
+      size += computeFieldSize(entry.getKey(), entry.getValue());
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+         fields.getOverflowEntries()) {
+      size += computeFieldSize(entry.getKey(), entry.getValue());
+    }
+    return size;
+  }
+
+  /**
+   * Like {@link #getSerializedSize} but uses MessageSet wire format.
+   */
+  public int getMessageSetSerializedSize() {
+    int size = 0;
+    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
+      size += getMessageSetSerializedSize(fields.getArrayEntryAt(i));
+    }
+    for (final Map.Entry<FieldDescriptorType, Object> entry :
+             fields.getOverflowEntries()) {
+      size += getMessageSetSerializedSize(entry);
+    }
+    return size;
+  }
+
+  private int getMessageSetSerializedSize(
+      final Map.Entry<FieldDescriptorType, Object> entry) {
+    final FieldDescriptorType descriptor = entry.getKey();
+    Object value = entry.getValue();
+    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE
+        && !descriptor.isRepeated() && !descriptor.isPacked()) {
+      if (value instanceof LazyField) {
+        return CodedOutputStream.computeLazyFieldMessageSetExtensionSize(
+            entry.getKey().getNumber(), (LazyField) value);
+      } else {
+        return CodedOutputStream.computeMessageSetExtensionSize(
+            entry.getKey().getNumber(), (MessageLite) value);
+      }
+    } else {
+      return computeFieldSize(descriptor, value);
+    }
+  }
+
+  /**
+   * Compute the number of bytes that would be needed to encode a
+   * single tag/value pair of arbitrary type.
+   *
+   * @param type   The field's type.
+   * @param number The field's number.
+   * @param value  Object representing the field's value.  Must be of the exact
+   *               type which would be returned by
+   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
+   *               this field.
+   */
+  private static int computeElementSize(
+      final WireFormat.FieldType type,
+      final int number, final Object value) {
+    int tagSize = CodedOutputStream.computeTagSize(number);
+    if (type == WireFormat.FieldType.GROUP) {
+      // Only count the end group tag for proto2 messages as for proto1 the end
+      // group tag will be counted as a part of getSerializedSize().
+        tagSize *= 2;
+    }
+    return tagSize + computeElementSizeNoTag(type, value);
+  }
+
+  /**
+   * Compute the number of bytes that would be needed to encode a
+   * particular value of arbitrary type, excluding tag.
+   *
+   * @param type   The field's type.
+   * @param value  Object representing the field's value.  Must be of the exact
+   *               type which would be returned by
+   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
+   *               this field.
+   */
+  static int computeElementSizeNoTag(
+      final WireFormat.FieldType type, final Object value) {
+    switch (type) {
+      // Note:  Minor violation of 80-char limit rule here because this would
+      //   actually be harder to read if we wrapped the lines.
+      case DOUBLE  : return CodedOutputStream.computeDoubleSizeNoTag  ((Double     )value);
+      case FLOAT   : return CodedOutputStream.computeFloatSizeNoTag   ((Float      )value);
+      case INT64   : return CodedOutputStream.computeInt64SizeNoTag   ((Long       )value);
+      case UINT64  : return CodedOutputStream.computeUInt64SizeNoTag  ((Long       )value);
+      case INT32   : return CodedOutputStream.computeInt32SizeNoTag   ((Integer    )value);
+      case FIXED64 : return CodedOutputStream.computeFixed64SizeNoTag ((Long       )value);
+      case FIXED32 : return CodedOutputStream.computeFixed32SizeNoTag ((Integer    )value);
+      case BOOL    : return CodedOutputStream.computeBoolSizeNoTag    ((Boolean    )value);
+      case GROUP   : return CodedOutputStream.computeGroupSizeNoTag   ((MessageLite)value);
+      case BYTES   :
+        if (value instanceof ByteString) {
+          return CodedOutputStream.computeBytesSizeNoTag((ByteString) value);
+        } else {
+          return CodedOutputStream.computeByteArraySizeNoTag((byte[]) value);
+        }
+      case STRING  :
+        if (value instanceof ByteString) {
+          return CodedOutputStream.computeBytesSizeNoTag((ByteString) value);
+        } else {
+          return CodedOutputStream.computeStringSizeNoTag((String) value);
+        }
+      case UINT32  : return CodedOutputStream.computeUInt32SizeNoTag  ((Integer    )value);
+      case SFIXED32: return CodedOutputStream.computeSFixed32SizeNoTag((Integer    )value);
+      case SFIXED64: return CodedOutputStream.computeSFixed64SizeNoTag((Long       )value);
+      case SINT32  : return CodedOutputStream.computeSInt32SizeNoTag  ((Integer    )value);
+      case SINT64  : return CodedOutputStream.computeSInt64SizeNoTag  ((Long       )value);
+
+      case MESSAGE:
+        if (value instanceof LazyField) {
+          return CodedOutputStream.computeLazyFieldSizeNoTag((LazyField) value);
+        } else {
+          return CodedOutputStream.computeMessageSizeNoTag((MessageLite) value);
+        }
+
+      case ENUM:
+        if (value instanceof Internal.EnumLite) {
+          return CodedOutputStream.computeEnumSizeNoTag(
+              ((Internal.EnumLite) value).getNumber());
+        } else {
+          return CodedOutputStream.computeEnumSizeNoTag((Integer) value);
+        }
+    }
+
+    throw new RuntimeException(
+      "There is no way to get here, but the compiler thinks otherwise.");
+  }
+
+  /**
+   * Compute the number of bytes needed to encode a particular field.
+   */
+  public static int computeFieldSize(final FieldDescriptorLite<?> descriptor,
+                                     final Object value) {
+    WireFormat.FieldType type = descriptor.getLiteType();
+    int number = descriptor.getNumber();
+    if (descriptor.isRepeated()) {
+      if (descriptor.isPacked()) {
+        int dataSize = 0;
+        for (final Object element : (List<?>)value) {
+          dataSize += computeElementSizeNoTag(type, element);
+        }
+        return dataSize +
+            CodedOutputStream.computeTagSize(number) +
+            CodedOutputStream.computeRawVarint32Size(dataSize);
+      } else {
+        int size = 0;
+        for (final Object element : (List<?>)value) {
+          size += computeElementSize(type, number, element);
+        }
+        return size;
+      }
+    } else {
+      return computeElementSize(type, number, value);
+    }
+  }
+}