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authorGravatar kenton@google.com <kenton@google.com@630680e5-0e50-0410-840e-4b1c322b438d>2009-07-29 01:13:20 +0000
committerGravatar kenton@google.com <kenton@google.com@630680e5-0e50-0410-840e-4b1c322b438d>2009-07-29 01:13:20 +0000
commit80b1d62bfcea65c59e2160da71dad84b1bd19cef (patch)
tree5423b830c53174fec83a7ea01ff0877e11c1ddb6 /src/google/protobuf/wire_format_lite.h
parentd2fd0638c309113ccae3731a58e30419f522269a (diff)
Submit recent changes from internal branch, including "lite mode" for
C++ and Java. See CHANGES.txt for more details.
Diffstat (limited to 'src/google/protobuf/wire_format_lite.h')
-rw-r--r--src/google/protobuf/wire_format_lite.h558
1 files changed, 558 insertions, 0 deletions
diff --git a/src/google/protobuf/wire_format_lite.h b/src/google/protobuf/wire_format_lite.h
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+++ b/src/google/protobuf/wire_format_lite.h
@@ -0,0 +1,558 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc. All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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: kenton@google.com (Kenton Varda)
+// atenasio@google.com (Chris Atenasio) (ZigZag transform)
+// wink@google.com (Wink Saville) (refactored from wire_format.h)
+// Based on original Protocol Buffers design by
+// Sanjay Ghemawat, Jeff Dean, and others.
+//
+// This header is logically internal, but is made public because it is used
+// from protocol-compiler-generated code, which may reside in other components.
+
+#ifndef GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__
+#define GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__
+
+#include <string>
+#include <google/protobuf/message_lite.h>
+
+namespace google {
+
+namespace protobuf {
+ namespace io {
+ class CodedInputStream; // coded_stream.h
+ class CodedOutputStream; // coded_stream.h
+ }
+}
+
+namespace protobuf {
+namespace internal {
+
+// This class is for internal use by the protocol buffer library and by
+// protocol-complier-generated message classes. It must not be called
+// directly by clients.
+//
+// This class contains helpers for implementing the binary protocol buffer
+// wire format without the need for reflection. Use WireFormat when using
+// reflection.
+//
+// This class is really a namespace that contains only static methods.
+class LIBPROTOBUF_EXPORT WireFormatLite {
+ public:
+
+ // -----------------------------------------------------------------
+ // Helper constants and functions related to the format. These are
+ // mostly meant for internal and generated code to use.
+
+ // The wire format is composed of a sequence of tag/value pairs, each
+ // of which contains the value of one field (or one element of a repeated
+ // field). Each tag is encoded as a varint. The lower bits of the tag
+ // identify its wire type, which specifies the format of the data to follow.
+ // The rest of the bits contain the field number. Each type of field (as
+ // declared by FieldDescriptor::Type, in descriptor.h) maps to one of
+ // these wire types. Immediately following each tag is the field's value,
+ // encoded in the format specified by the wire type. Because the tag
+ // identifies the encoding of this data, it is possible to skip
+ // unrecognized fields for forwards compatibility.
+
+ enum WireType {
+ WIRETYPE_VARINT = 0,
+ WIRETYPE_FIXED64 = 1,
+ WIRETYPE_LENGTH_DELIMITED = 2,
+ WIRETYPE_START_GROUP = 3,
+ WIRETYPE_END_GROUP = 4,
+ WIRETYPE_FIXED32 = 5,
+ };
+
+ // Lite alternative to FieldDescriptor::Type. Must be kept in sync.
+ enum FieldType {
+ TYPE_DOUBLE = 1,
+ TYPE_FLOAT = 2,
+ TYPE_INT64 = 3,
+ TYPE_UINT64 = 4,
+ TYPE_INT32 = 5,
+ TYPE_FIXED64 = 6,
+ TYPE_FIXED32 = 7,
+ TYPE_BOOL = 8,
+ TYPE_STRING = 9,
+ TYPE_GROUP = 10,
+ TYPE_MESSAGE = 11,
+ TYPE_BYTES = 12,
+ TYPE_UINT32 = 13,
+ TYPE_ENUM = 14,
+ TYPE_SFIXED32 = 15,
+ TYPE_SFIXED64 = 16,
+ TYPE_SINT32 = 17,
+ TYPE_SINT64 = 18,
+ MAX_FIELD_TYPE = 18,
+ };
+
+ // Lite alternative to FieldDescriptor::CppType. Must be kept in sync.
+ enum CppType {
+ CPPTYPE_INT32 = 1,
+ CPPTYPE_INT64 = 2,
+ CPPTYPE_UINT32 = 3,
+ CPPTYPE_UINT64 = 4,
+ CPPTYPE_DOUBLE = 5,
+ CPPTYPE_FLOAT = 6,
+ CPPTYPE_BOOL = 7,
+ CPPTYPE_ENUM = 8,
+ CPPTYPE_STRING = 9,
+ CPPTYPE_MESSAGE = 10,
+ MAX_CPPTYPE = 10,
+ };
+
+ // Helper method to get the CppType for a particular Type.
+ static CppType FieldTypeToCppType(FieldType type);
+
+ // Given a FieldSescriptor::Type return its WireType
+ static inline WireFormatLite::WireType WireTypeForFieldType(
+ WireFormatLite::FieldType type) {
+ return kWireTypeForFieldType[type];
+ }
+
+ // Number of bits in a tag which identify the wire type.
+ static const int kTagTypeBits = 3;
+ // Mask for those bits.
+ static const uint32 kTagTypeMask = (1 << kTagTypeBits) - 1;
+
+ // Helper functions for encoding and decoding tags. (Inlined below and in
+ // _inl.h)
+ //
+ // This is different from MakeTag(field->number(), field->type()) in the case
+ // of packed repeated fields.
+ static uint32 MakeTag(int field_number, WireType type);
+ static WireType GetTagWireType(uint32 tag);
+ static int GetTagFieldNumber(uint32 tag);
+
+ // Compute the byte size of a tag. For groups, this includes both the start
+ // and end tags.
+ static inline int TagSize(int field_number, WireFormatLite::FieldType type);
+
+ // Skips a field value with the given tag. The input should start
+ // positioned immediately after the tag. Skipped values are simply discarded,
+ // not recorded anywhere. See WireFormat::SkipField() for a version that
+ // records to an UnknownFieldSet.
+ static bool SkipField(io::CodedInputStream* input, uint32 tag);
+
+ // Reads and ignores a message from the input. Skipped values are simply
+ // discarded, not recorded anywhere. See WireFormat::SkipMessage() for a
+ // version that records to an UnknownFieldSet.
+ static bool SkipMessage(io::CodedInputStream* input);
+
+// This macro does the same thing as WireFormatLite::MakeTag(), but the
+// result is usable as a compile-time constant, which makes it usable
+// as a switch case or a template input. WireFormatLite::MakeTag() is more
+// type-safe, though, so prefer it if possible.
+#define GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(FIELD_NUMBER, TYPE) \
+ static_cast<uint32>( \
+ ((FIELD_NUMBER) << ::google::protobuf::internal::WireFormatLite::kTagTypeBits) \
+ | (TYPE))
+
+ // These are the tags for the old MessageSet format, which was defined as:
+ // message MessageSet {
+ // repeated group Item = 1 {
+ // required int32 type_id = 2;
+ // required string message = 3;
+ // }
+ // }
+ static const int kMessageSetItemStartTag =
+ GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(1, WireFormatLite::WIRETYPE_START_GROUP);
+ static const int kMessageSetItemEndTag =
+ GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(1, WireFormatLite::WIRETYPE_END_GROUP);
+ static const int kMessageSetTypeIdTag =
+ GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(2, WireFormatLite::WIRETYPE_VARINT);
+ static const int kMessageSetMessageTag =
+ GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(3, WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+
+ // Byte size of all tags of a MessageSet::Item combined.
+ static const int kMessageSetItemTagsSize;
+
+ // Helper functions for converting between floats/doubles and IEEE-754
+ // uint32s/uint64s so that they can be written. (Assumes your platform
+ // uses IEEE-754 floats.)
+ static uint32 EncodeFloat(float value);
+ static float DecodeFloat(uint32 value);
+ static uint64 EncodeDouble(double value);
+ static double DecodeDouble(uint64 value);
+
+ // Helper functions for mapping signed integers to unsigned integers in
+ // such a way that numbers with small magnitudes will encode to smaller
+ // varints. If you simply static_cast a negative number to an unsigned
+ // number and varint-encode it, it will always take 10 bytes, defeating
+ // the purpose of varint. So, for the "sint32" and "sint64" field types,
+ // we ZigZag-encode the values.
+ static uint32 ZigZagEncode32(int32 n);
+ static int32 ZigZagDecode32(uint32 n);
+ static uint64 ZigZagEncode64(int64 n);
+ static int64 ZigZagDecode64(uint64 n);
+
+ // =================================================================
+ // Methods for reading/writing individual field. The implementations
+ // of these methods are defined in wire_format_lite_inl.h; you must #include
+ // that file to use these.
+
+// Avoid ugly line wrapping
+#define input io::CodedInputStream* input
+#define output io::CodedOutputStream* output
+#define field_number int field_number
+#define INL GOOGLE_ATTRIBUTE_ALWAYS_INLINE
+
+ // Read fields, not including tags. The assumption is that you already
+ // read the tag to determine what field to read.
+ static inline bool ReadInt32 (input, int32* value);
+ static inline bool ReadInt64 (input, int64* value);
+ static inline bool ReadUInt32 (input, uint32* value);
+ static inline bool ReadUInt64 (input, uint64* value);
+ static inline bool ReadSInt32 (input, int32* value);
+ static inline bool ReadSInt64 (input, int64* value);
+ static inline bool ReadFixed32 (input, uint32* value);
+ static inline bool ReadFixed64 (input, uint64* value);
+ static inline bool ReadSFixed32(input, int32* value);
+ static inline bool ReadSFixed64(input, int64* value);
+ static inline bool ReadFloat (input, float* value);
+ static inline bool ReadDouble (input, double* value);
+ static inline bool ReadBool (input, bool* value);
+ static inline bool ReadEnum (input, int* value);
+
+ static inline bool ReadString(input, string* value);
+ static inline bool ReadBytes (input, string* value);
+
+ static inline bool ReadGroup (field_number, input, MessageLite* value);
+ static inline bool ReadMessage(input, MessageLite* value);
+
+ // Like above, but de-virtualize the call to MergePartialFromCodedStream().
+ // The pointer must point at an instance of MessageType, *not* a subclass (or
+ // the subclass must not override MergePartialFromCodedStream()).
+ template<typename MessageType>
+ static inline bool ReadGroupNoVirtual(field_number, input,
+ MessageType* value);
+ template<typename MessageType>
+ static inline bool ReadMessageNoVirtual(input, MessageType* value);
+
+ // Write a tag. The Write*() functions typically include the tag, so
+ // normally there's no need to call this unless using the Write*NoTag()
+ // variants.
+ static inline void WriteTag(field_number, WireType type, output) INL;
+
+ // Write fields, without tags.
+ static inline void WriteInt32NoTag (int32 value, output) INL;
+ static inline void WriteInt64NoTag (int64 value, output) INL;
+ static inline void WriteUInt32NoTag (uint32 value, output) INL;
+ static inline void WriteUInt64NoTag (uint64 value, output) INL;
+ static inline void WriteSInt32NoTag (int32 value, output) INL;
+ static inline void WriteSInt64NoTag (int64 value, output) INL;
+ static inline void WriteFixed32NoTag (uint32 value, output) INL;
+ static inline void WriteFixed64NoTag (uint64 value, output) INL;
+ static inline void WriteSFixed32NoTag(int32 value, output) INL;
+ static inline void WriteSFixed64NoTag(int64 value, output) INL;
+ static inline void WriteFloatNoTag (float value, output) INL;
+ static inline void WriteDoubleNoTag (double value, output) INL;
+ static inline void WriteBoolNoTag (bool value, output) INL;
+ static inline void WriteEnumNoTag (int value, output) INL;
+
+ // Write fields, including tags.
+ static inline void WriteInt32 (field_number, int32 value, output) INL;
+ static inline void WriteInt64 (field_number, int64 value, output) INL;
+ static inline void WriteUInt32 (field_number, uint32 value, output) INL;
+ static inline void WriteUInt64 (field_number, uint64 value, output) INL;
+ static inline void WriteSInt32 (field_number, int32 value, output) INL;
+ static inline void WriteSInt64 (field_number, int64 value, output) INL;
+ static inline void WriteFixed32 (field_number, uint32 value, output) INL;
+ static inline void WriteFixed64 (field_number, uint64 value, output) INL;
+ static inline void WriteSFixed32(field_number, int32 value, output) INL;
+ static inline void WriteSFixed64(field_number, int64 value, output) INL;
+ static inline void WriteFloat (field_number, float value, output) INL;
+ static inline void WriteDouble (field_number, double value, output) INL;
+ static inline void WriteBool (field_number, bool value, output) INL;
+ static inline void WriteEnum (field_number, int value, output) INL;
+
+ static inline void WriteString(field_number, const string& value, output) INL;
+ static inline void WriteBytes (field_number, const string& value, output) INL;
+
+ static inline void WriteGroup(
+ field_number, const MessageLite& value, output) INL;
+ static inline void WriteMessage(
+ field_number, const MessageLite& value, output) INL;
+
+ // Like above, but de-virtualize the call to SerializeWithCachedSizes(). The
+ // pointer must point at an instance of MessageType, *not* a subclass (or
+ // the subclass must not override SerializeWithCachedSizes()).
+ template<typename MessageType>
+ static inline void WriteGroupNoVirtual(
+ field_number, const MessageType& value, output) INL;
+ template<typename MessageType>
+ static inline void WriteMessageNoVirtual(
+ field_number, const MessageType& value, output) INL;
+
+#undef output
+#define output uint8* target
+
+ // Like above, but use only *ToArray methods of CodedOutputStream.
+ static inline uint8* WriteTagToArray(field_number, WireType type, output) INL;
+
+ // Write fields, without tags.
+ static inline uint8* WriteInt32NoTagToArray (int32 value, output) INL;
+ static inline uint8* WriteInt64NoTagToArray (int64 value, output) INL;
+ static inline uint8* WriteUInt32NoTagToArray (uint32 value, output) INL;
+ static inline uint8* WriteUInt64NoTagToArray (uint64 value, output) INL;
+ static inline uint8* WriteSInt32NoTagToArray (int32 value, output) INL;
+ static inline uint8* WriteSInt64NoTagToArray (int64 value, output) INL;
+ static inline uint8* WriteFixed32NoTagToArray (uint32 value, output) INL;
+ static inline uint8* WriteFixed64NoTagToArray (uint64 value, output) INL;
+ static inline uint8* WriteSFixed32NoTagToArray(int32 value, output) INL;
+ static inline uint8* WriteSFixed64NoTagToArray(int64 value, output) INL;
+ static inline uint8* WriteFloatNoTagToArray (float value, output) INL;
+ static inline uint8* WriteDoubleNoTagToArray (double value, output) INL;
+ static inline uint8* WriteBoolNoTagToArray (bool value, output) INL;
+ static inline uint8* WriteEnumNoTagToArray (int value, output) INL;
+
+ // Write fields, including tags.
+ static inline uint8* WriteInt32ToArray(
+ field_number, int32 value, output) INL;
+ static inline uint8* WriteInt64ToArray(
+ field_number, int64 value, output) INL;
+ static inline uint8* WriteUInt32ToArray(
+ field_number, uint32 value, output) INL;
+ static inline uint8* WriteUInt64ToArray(
+ field_number, uint64 value, output) INL;
+ static inline uint8* WriteSInt32ToArray(
+ field_number, int32 value, output) INL;
+ static inline uint8* WriteSInt64ToArray(
+ field_number, int64 value, output) INL;
+ static inline uint8* WriteFixed32ToArray(
+ field_number, uint32 value, output) INL;
+ static inline uint8* WriteFixed64ToArray(
+ field_number, uint64 value, output) INL;
+ static inline uint8* WriteSFixed32ToArray(
+ field_number, int32 value, output) INL;
+ static inline uint8* WriteSFixed64ToArray(
+ field_number, int64 value, output) INL;
+ static inline uint8* WriteFloatToArray(
+ field_number, float value, output) INL;
+ static inline uint8* WriteDoubleToArray(
+ field_number, double value, output) INL;
+ static inline uint8* WriteBoolToArray(
+ field_number, bool value, output) INL;
+ static inline uint8* WriteEnumToArray(
+ field_number, int value, output) INL;
+
+ static inline uint8* WriteStringToArray(
+ field_number, const string& value, output) INL;
+ static inline uint8* WriteBytesToArray(
+ field_number, const string& value, output) INL;
+
+ static inline uint8* WriteGroupToArray(
+ field_number, const MessageLite& value, output) INL;
+ static inline uint8* WriteMessageToArray(
+ field_number, const MessageLite& value, output) INL;
+
+ // Like above, but de-virtualize the call to SerializeWithCachedSizes(). The
+ // pointer must point at an instance of MessageType, *not* a subclass (or
+ // the subclass must not override SerializeWithCachedSizes()).
+ template<typename MessageType>
+ static inline uint8* WriteGroupNoVirtualToArray(
+ field_number, const MessageType& value, output) INL;
+ template<typename MessageType>
+ static inline uint8* WriteMessageNoVirtualToArray(
+ field_number, const MessageType& value, output) INL;
+
+#undef output
+#undef input
+#undef INL
+
+#undef field_number
+
+ // Compute the byte size of a field. The XxSize() functions do NOT include
+ // the tag, so you must also call TagSize(). (This is because, for repeated
+ // fields, you should only call TagSize() once and multiply it by the element
+ // count, but you may have to call XxSize() for each individual element.)
+ static inline int Int32Size ( int32 value);
+ static inline int Int64Size ( int64 value);
+ static inline int UInt32Size (uint32 value);
+ static inline int UInt64Size (uint64 value);
+ static inline int SInt32Size ( int32 value);
+ static inline int SInt64Size ( int64 value);
+ static inline int EnumSize ( int value);
+
+ // These types always have the same size.
+ static const int kFixed32Size = 4;
+ static const int kFixed64Size = 8;
+ static const int kSFixed32Size = 4;
+ static const int kSFixed64Size = 8;
+ static const int kFloatSize = 4;
+ static const int kDoubleSize = 8;
+ static const int kBoolSize = 1;
+
+ static inline int StringSize(const string& value);
+ static inline int BytesSize (const string& value);
+
+ static inline int GroupSize (const MessageLite& value);
+ static inline int MessageSize(const MessageLite& value);
+
+ // Like above, but de-virtualize the call to ByteSize(). The
+ // pointer must point at an instance of MessageType, *not* a subclass (or
+ // the subclass must not override ByteSize()).
+ template<typename MessageType>
+ static inline int GroupSizeNoVirtual (const MessageType& value);
+ template<typename MessageType>
+ static inline int MessageSizeNoVirtual(const MessageType& value);
+
+ private:
+ static const CppType kFieldTypeToCppTypeMap[];
+ static const WireFormatLite::WireType kWireTypeForFieldType[];
+
+ GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(WireFormatLite);
+};
+
+// A class which deals with unknown values. The default implementation just
+// discards them. WireFormat defines a subclass which writes to an
+// UnknownFieldSet. This class is used by ExtensionSet::ParseField(), since
+// ExtensionSet is part of the lite library but UnknownFieldSet is not.
+class LIBPROTOBUF_EXPORT FieldSkipper {
+ public:
+ FieldSkipper() {}
+ virtual ~FieldSkipper() {}
+
+ // Skip a field whose tag has already been consumed.
+ virtual bool SkipField(io::CodedInputStream* input, uint32 tag);
+
+ // Skip an entire message or group, up to an end-group tag (which is consumed)
+ // or end-of-stream.
+ virtual bool SkipMessage(io::CodedInputStream* input);
+
+ // Deal with an already-parsed unrecognized enum value. The default
+ // implementation does nothing, but the UnknownFieldSet-based implementation
+ // saves it as an unknown varint.
+ virtual void SkipUnknownEnum(int field_number, int value);
+};
+
+// inline methods ====================================================
+
+inline WireFormatLite::CppType
+WireFormatLite::FieldTypeToCppType(FieldType type) {
+ return kFieldTypeToCppTypeMap[type];
+}
+
+inline uint32 WireFormatLite::MakeTag(int field_number, WireType type) {
+ return GOOGLE_PROTOBUF_WIRE_FORMAT_MAKE_TAG(field_number, type);
+}
+
+inline WireFormatLite::WireType WireFormatLite::GetTagWireType(uint32 tag) {
+ return static_cast<WireType>(tag & kTagTypeMask);
+}
+
+inline int WireFormatLite::GetTagFieldNumber(uint32 tag) {
+ return static_cast<int>(tag >> kTagTypeBits);
+}
+
+inline int WireFormatLite::TagSize(int field_number,
+ WireFormatLite::FieldType type) {
+ int result = io::CodedOutputStream::VarintSize32(
+ field_number << kTagTypeBits);
+ if (type == TYPE_GROUP) {
+ // Groups have both a start and an end tag.
+ return result * 2;
+ } else {
+ return result;
+ }
+}
+
+inline uint32 WireFormatLite::EncodeFloat(float value) {
+ union {float f; uint32 i;};
+ f = value;
+ return i;
+}
+
+inline float WireFormatLite::DecodeFloat(uint32 value) {
+ union {float f; uint32 i;};
+ i = value;
+ return f;
+}
+
+inline uint64 WireFormatLite::EncodeDouble(double value) {
+ union {double f; uint64 i;};
+ f = value;
+ return i;
+}
+
+inline double WireFormatLite::DecodeDouble(uint64 value) {
+ union {double f; uint64 i;};
+ i = value;
+ return f;
+}
+
+// ZigZag Transform: Encodes signed integers so that they can be
+// effectively used with varint encoding.
+//
+// varint operates on unsigned integers, encoding smaller numbers into
+// fewer bytes. If you try to use it on a signed integer, it will treat
+// this number as a very large unsigned integer, which means that even
+// small signed numbers like -1 will take the maximum number of bytes
+// (10) to encode. ZigZagEncode() maps signed integers to unsigned
+// in such a way that those with a small absolute value will have smaller
+// encoded values, making them appropriate for encoding using varint.
+//
+// int32 -> uint32
+// -------------------------
+// 0 -> 0
+// -1 -> 1
+// 1 -> 2
+// -2 -> 3
+// ... -> ...
+// 2147483647 -> 4294967294
+// -2147483648 -> 4294967295
+//
+// >> encode >>
+// << decode <<
+
+inline uint32 WireFormatLite::ZigZagEncode32(int32 n) {
+ // Note: the right-shift must be arithmetic
+ return (n << 1) ^ (n >> 31);
+}
+
+inline int32 WireFormatLite::ZigZagDecode32(uint32 n) {
+ return (n >> 1) ^ -static_cast<int32>(n & 1);
+}
+
+inline uint64 WireFormatLite::ZigZagEncode64(int64 n) {
+ // Note: the right-shift must be arithmetic
+ return (n << 1) ^ (n >> 63);
+}
+
+inline int64 WireFormatLite::ZigZagDecode64(uint64 n) {
+ return (n >> 1) ^ -static_cast<int64>(n & 1);
+}
+
+} // namespace internal
+} // namespace protobuf
+
+} // namespace google
+#endif // GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_H__