diff --git a/src/google/protobuf/message.h b/src/google/protobuf/message.h
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+// 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: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// Defines Message, the abstract interface implemented by non-lite
+// protocol message objects.  Although it's possible to implement this
+// interface manually, most users will use the protocol compiler to
+// generate implementations.
+//
+// Example usage:
+//
+// Say you have a message defined as:
+//
+//   message Foo {
+//     optional string text = 1;
+//     repeated int32 numbers = 2;
+//   }
+//
+// Then, if you used the protocol compiler to generate a class from the above
+// definition, you could use it like so:
+//
+//   string data;  // Will store a serialized version of the message.
+//
+//   {
+//     // Create a message and serialize it.
+//     Foo foo;
+//     foo.set_text("Hello World!");
+//     foo.add_numbers(1);
+//     foo.add_numbers(5);
+//     foo.add_numbers(42);
+//
+//     foo.SerializeToString(&data);
+//   }
+//
+//   {
+//     // Parse the serialized message and check that it contains the
+//     // correct data.
+//     Foo foo;
+//     foo.ParseFromString(data);
+//
+//     assert(foo.text() == "Hello World!");
+//     assert(foo.numbers_size() == 3);
+//     assert(foo.numbers(0) == 1);
+//     assert(foo.numbers(1) == 5);
+//     assert(foo.numbers(2) == 42);
+//   }
+//
+//   {
+//     // Same as the last block, but do it dynamically via the Message
+//     // reflection interface.
+//     Message* foo = new Foo;
+//     const Descriptor* descriptor = foo->GetDescriptor();
+//
+//     // Get the descriptors for the fields we're interested in and verify
+//     // their types.
+//     const FieldDescriptor* text_field = descriptor->FindFieldByName("text");
+//     assert(text_field != NULL);
+//     assert(text_field->type() == FieldDescriptor::TYPE_STRING);
+//     assert(text_field->label() == FieldDescriptor::LABEL_OPTIONAL);
+//     const FieldDescriptor* numbers_field = descriptor->
+//                                            FindFieldByName("numbers");
+//     assert(numbers_field != NULL);
+//     assert(numbers_field->type() == FieldDescriptor::TYPE_INT32);
+//     assert(numbers_field->label() == FieldDescriptor::LABEL_REPEATED);
+//
+//     // Parse the message.
+//     foo->ParseFromString(data);
+//
+//     // Use the reflection interface to examine the contents.
+//     const Reflection* reflection = foo->GetReflection();
+//     assert(reflection->GetString(*foo, text_field) == "Hello World!");
+//     assert(reflection->FieldSize(*foo, numbers_field) == 3);
+//     assert(reflection->GetRepeatedInt32(*foo, numbers_field, 0) == 1);
+//     assert(reflection->GetRepeatedInt32(*foo, numbers_field, 1) == 5);
+//     assert(reflection->GetRepeatedInt32(*foo, numbers_field, 2) == 42);
+//
+//     delete foo;
+//   }
+
+#ifndef GOOGLE_PROTOBUF_MESSAGE_H__
+#define GOOGLE_PROTOBUF_MESSAGE_H__
+
+#include <iosfwd>
+#include <string>
+#include <google/protobuf/stubs/type_traits.h>
+#include <vector>
+
+#include <google/protobuf/arena.h>
+#include <google/protobuf/message_lite.h>
+
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/descriptor.h>
+
+
+#define GOOGLE_PROTOBUF_HAS_ONEOF
+#define GOOGLE_PROTOBUF_HAS_ARENAS
+
+namespace google {
+namespace protobuf {
+
+// Defined in this file.
+class Message;
+class Reflection;
+class MessageFactory;
+
+// Defined in other files.
+class MapKey;
+class MapValueRef;
+class MapIterator;
+class MapReflectionTester;
+
+namespace internal {
+class MapFieldBase;
+}
+class UnknownFieldSet;         // unknown_field_set.h
+namespace io {
+class ZeroCopyInputStream;     // zero_copy_stream.h
+class ZeroCopyOutputStream;    // zero_copy_stream.h
+class CodedInputStream;        // coded_stream.h
+class CodedOutputStream;       // coded_stream.h
+}
+namespace python {
+class MapReflectionFriend;     // scalar_map_container.h
+}
+
+
+template<typename T>
+class RepeatedField;     // repeated_field.h
+
+template<typename T>
+class RepeatedPtrField;  // repeated_field.h
+
+// A container to hold message metadata.
+struct Metadata {
+  const Descriptor* descriptor;
+  const Reflection* reflection;
+};
+
+// Abstract interface for protocol messages.
+//
+// See also MessageLite, which contains most every-day operations.  Message
+// adds descriptors and reflection on top of that.
+//
+// The methods of this class that are virtual but not pure-virtual have
+// default implementations based on reflection.  Message classes which are
+// optimized for speed will want to override these with faster implementations,
+// but classes optimized for code size may be happy with keeping them.  See
+// the optimize_for option in descriptor.proto.
+class LIBPROTOBUF_EXPORT Message : public MessageLite {
+ public:
+  inline Message() {}
+  virtual ~Message();
+
+  // Basic Operations ------------------------------------------------
+
+  // Construct a new instance of the same type.  Ownership is passed to the
+  // caller.  (This is also defined in MessageLite, but is defined again here
+  // for return-type covariance.)
+  virtual Message* New() const = 0;
+
+  // Construct a new instance on the arena. Ownership is passed to the caller
+  // if arena is a NULL. Default implementation allows for API compatibility
+  // during the Arena transition.
+  virtual Message* New(::google::protobuf::Arena* arena) const {
+    Message* message = New();
+    if (arena != NULL) {
+      arena->Own(message);
+    }
+    return message;
+  }
+
+  // Make this message into a copy of the given message.  The given message
+  // must have the same descriptor, but need not necessarily be the same class.
+  // By default this is just implemented as "Clear(); MergeFrom(from);".
+  virtual void CopyFrom(const Message& from);
+
+  // Merge the fields from the given message into this message.  Singular
+  // fields will be overwritten, if specified in from, except for embedded
+  // messages which will be merged.  Repeated fields will be concatenated.
+  // The given message must be of the same type as this message (i.e. the
+  // exact same class).
+  virtual void MergeFrom(const Message& from);
+
+  // Verifies that IsInitialized() returns true.  GOOGLE_CHECK-fails otherwise, with
+  // a nice error message.
+  void CheckInitialized() const;
+
+  // Slowly build a list of all required fields that are not set.
+  // This is much, much slower than IsInitialized() as it is implemented
+  // purely via reflection.  Generally, you should not call this unless you
+  // have already determined that an error exists by calling IsInitialized().
+  void FindInitializationErrors(std::vector<string>* errors) const;
+
+  // Like FindInitializationErrors, but joins all the strings, delimited by
+  // commas, and returns them.
+  string InitializationErrorString() const;
+
+  // Clears all unknown fields from this message and all embedded messages.
+  // Normally, if unknown tag numbers are encountered when parsing a message,
+  // the tag and value are stored in the message's UnknownFieldSet and
+  // then written back out when the message is serialized.  This allows servers
+  // which simply route messages to other servers to pass through messages
+  // that have new field definitions which they don't yet know about.  However,
+  // this behavior can have security implications.  To avoid it, call this
+  // method after parsing.
+  //
+  // See Reflection::GetUnknownFields() for more on unknown fields.
+  virtual void DiscardUnknownFields();
+
+  // Computes (an estimate of) the total number of bytes currently used for
+  // storing the message in memory.  The default implementation calls the
+  // Reflection object's SpaceUsed() method.
+  //
+  // SpaceUsed() is noticeably slower than ByteSize(), as it is implemented
+  // using reflection (rather than the generated code implementation for
+  // ByteSize()). Like ByteSize(), its CPU time is linear in the number of
+  // fields defined for the proto.
+  virtual int SpaceUsed() const;
+
+  // Debugging & Testing----------------------------------------------
+
+  // Generates a human readable form of this message, useful for debugging
+  // and other purposes.
+  string DebugString() const;
+  // Like DebugString(), but with less whitespace.
+  string ShortDebugString() const;
+  // Like DebugString(), but do not escape UTF-8 byte sequences.
+  string Utf8DebugString() const;
+  // Convenience function useful in GDB.  Prints DebugString() to stdout.
+  void PrintDebugString() const;
+
+  // Heavy I/O -------------------------------------------------------
+  // Additional parsing and serialization methods not implemented by
+  // MessageLite because they are not supported by the lite library.
+
+  // Parse a protocol buffer from a file descriptor.  If successful, the entire
+  // input will be consumed.
+  bool ParseFromFileDescriptor(int file_descriptor);
+  // Like ParseFromFileDescriptor(), but accepts messages that are missing
+  // required fields.
+  bool ParsePartialFromFileDescriptor(int file_descriptor);
+  // Parse a protocol buffer from a C++ istream.  If successful, the entire
+  // input will be consumed.
+  bool ParseFromIstream(istream* input);
+  // Like ParseFromIstream(), but accepts messages that are missing
+  // required fields.
+  bool ParsePartialFromIstream(istream* input);
+
+  // Serialize the message and write it to the given file descriptor.  All
+  // required fields must be set.
+  bool SerializeToFileDescriptor(int file_descriptor) const;
+  // Like SerializeToFileDescriptor(), but allows missing required fields.
+  bool SerializePartialToFileDescriptor(int file_descriptor) const;
+  // Serialize the message and write it to the given C++ ostream.  All
+  // required fields must be set.
+  bool SerializeToOstream(ostream* output) const;
+  // Like SerializeToOstream(), but allows missing required fields.
+  bool SerializePartialToOstream(ostream* output) const;
+
+
+  // Reflection-based methods ----------------------------------------
+  // These methods are pure-virtual in MessageLite, but Message provides
+  // reflection-based default implementations.
+
+  virtual string GetTypeName() const;
+  virtual void Clear();
+  virtual bool IsInitialized() const;
+  virtual void CheckTypeAndMergeFrom(const MessageLite& other);
+  virtual bool MergePartialFromCodedStream(io::CodedInputStream* input);
+  virtual int ByteSize() const;
+  virtual void SerializeWithCachedSizes(io::CodedOutputStream* output) const;
+
+ private:
+  // This is called only by the default implementation of ByteSize(), to
+  // update the cached size.  If you override ByteSize(), you do not need
+  // to override this.  If you do not override ByteSize(), you MUST override
+  // this; the default implementation will crash.
+  //
+  // The method is private because subclasses should never call it; only
+  // override it.  Yes, C++ lets you do that.  Crazy, huh?
+  virtual void SetCachedSize(int size) const;
+
+ public:
+
+  // Introspection ---------------------------------------------------
+
+  // Typedef for backwards-compatibility.
+  typedef google::protobuf::Reflection Reflection;
+
+  // Get a Descriptor for this message's type.  This describes what
+  // fields the message contains, the types of those fields, etc.
+  const Descriptor* GetDescriptor() const { return GetMetadata().descriptor; }
+
+  // Get the Reflection interface for this Message, which can be used to
+  // read and modify the fields of the Message dynamically (in other words,
+  // without knowing the message type at compile time).  This object remains
+  // property of the Message.
+  //
+  // This method remains virtual in case a subclass does not implement
+  // reflection and wants to override the default behavior.
+  virtual const Reflection* GetReflection() const {
+    return GetMetadata().reflection;
+  }
+
+ protected:
+  // Get a struct containing the metadata for the Message. Most subclasses only
+  // need to implement this method, rather than the GetDescriptor() and
+  // GetReflection() wrappers.
+  virtual Metadata GetMetadata() const  = 0;
+
+
+ private:
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Message);
+};
+
+namespace internal {
+// Forward-declare interfaces used to implement RepeatedFieldRef.
+// These are protobuf internals that users shouldn't care about.
+class RepeatedFieldAccessor;
+}  // namespace internal
+
+// Forward-declare RepeatedFieldRef templates. The second type parameter is
+// used for SFINAE tricks. Users should ignore it.
+template<typename T, typename Enable = void>
+class RepeatedFieldRef;
+
+template<typename T, typename Enable = void>
+class MutableRepeatedFieldRef;
+
+// This interface contains methods that can be used to dynamically access
+// and modify the fields of a protocol message.  Their semantics are
+// similar to the accessors the protocol compiler generates.
+//
+// To get the Reflection for a given Message, call Message::GetReflection().
+//
+// This interface is separate from Message only for efficiency reasons;
+// the vast majority of implementations of Message will share the same
+// implementation of Reflection (GeneratedMessageReflection,
+// defined in generated_message.h), and all Messages of a particular class
+// should share the same Reflection object (though you should not rely on
+// the latter fact).
+//
+// There are several ways that these methods can be used incorrectly.  For
+// example, any of the following conditions will lead to undefined
+// results (probably assertion failures):
+// - The FieldDescriptor is not a field of this message type.
+// - The method called is not appropriate for the field's type.  For
+//   each field type in FieldDescriptor::TYPE_*, there is only one
+//   Get*() method, one Set*() method, and one Add*() method that is
+//   valid for that type.  It should be obvious which (except maybe
+//   for TYPE_BYTES, which are represented using strings in C++).
+// - A Get*() or Set*() method for singular fields is called on a repeated
+//   field.
+// - GetRepeated*(), SetRepeated*(), or Add*() is called on a non-repeated
+//   field.
+// - The Message object passed to any method is not of the right type for
+//   this Reflection object (i.e. message.GetReflection() != reflection).
+//
+// You might wonder why there is not any abstract representation for a field
+// of arbitrary type.  E.g., why isn't there just a "GetField()" method that
+// returns "const Field&", where "Field" is some class with accessors like
+// "GetInt32Value()".  The problem is that someone would have to deal with
+// allocating these Field objects.  For generated message classes, having to
+// allocate space for an additional object to wrap every field would at least
+// double the message's memory footprint, probably worse.  Allocating the
+// objects on-demand, on the other hand, would be expensive and prone to
+// memory leaks.  So, instead we ended up with this flat interface.
+//
+// TODO(kenton):  Create a utility class which callers can use to read and
+//   write fields from a Reflection without paying attention to the type.
+class LIBPROTOBUF_EXPORT Reflection {
+ public:
+  inline Reflection() {}
+  virtual ~Reflection();
+
+  // Get the UnknownFieldSet for the message.  This contains fields which
+  // were seen when the Message was parsed but were not recognized according
+  // to the Message's definition. For proto3 protos, this method will always
+  // return an empty UnknownFieldSet.
+  virtual const UnknownFieldSet& GetUnknownFields(
+      const Message& message) const = 0;
+  // Get a mutable pointer to the UnknownFieldSet for the message.  This
+  // contains fields which were seen when the Message was parsed but were not
+  // recognized according to the Message's definition. For proto3 protos, this
+  // method will return a valid mutable UnknownFieldSet pointer but modifying
+  // it won't affect the serialized bytes of the message.
+  virtual UnknownFieldSet* MutableUnknownFields(Message* message) const = 0;
+
+  // Estimate the amount of memory used by the message object.
+  virtual int SpaceUsed(const Message& message) const = 0;
+
+  // Check if the given non-repeated field is set.
+  virtual bool HasField(const Message& message,
+                        const FieldDescriptor* field) const = 0;
+
+  // Get the number of elements of a repeated field.
+  virtual int FieldSize(const Message& message,
+                        const FieldDescriptor* field) const = 0;
+
+  // Clear the value of a field, so that HasField() returns false or
+  // FieldSize() returns zero.
+  virtual void ClearField(Message* message,
+                          const FieldDescriptor* field) const = 0;
+
+  // Check if the oneof is set. Returns true if any field in oneof
+  // is set, false otherwise.
+  // TODO(jieluo) - make it pure virtual after updating all
+  // the subclasses.
+  virtual bool HasOneof(const Message& /*message*/,
+                        const OneofDescriptor* /*oneof_descriptor*/) const {
+    return false;
+  }
+
+  virtual void ClearOneof(Message* /*message*/,
+                          const OneofDescriptor* /*oneof_descriptor*/) const {}
+
+  // Returns the field descriptor if the oneof is set. NULL otherwise.
+  // TODO(jieluo) - make it pure virtual.
+  virtual const FieldDescriptor* GetOneofFieldDescriptor(
+      const Message& /*message*/,
+      const OneofDescriptor* /*oneof_descriptor*/) const {
+    return NULL;
+  }
+
+  // Removes the last element of a repeated field.
+  // We don't provide a way to remove any element other than the last
+  // because it invites inefficient use, such as O(n^2) filtering loops
+  // that should have been O(n).  If you want to remove an element other
+  // than the last, the best way to do it is to re-arrange the elements
+  // (using Swap()) so that the one you want removed is at the end, then
+  // call RemoveLast().
+  virtual void RemoveLast(Message* message,
+                          const FieldDescriptor* field) const = 0;
+  // Removes the last element of a repeated message field, and returns the
+  // pointer to the caller.  Caller takes ownership of the returned pointer.
+  virtual Message* ReleaseLast(Message* message,
+                               const FieldDescriptor* field) const = 0;
+
+  // Swap the complete contents of two messages.
+  virtual void Swap(Message* message1, Message* message2) const = 0;
+
+  // Swap fields listed in fields vector of two messages.
+  virtual void SwapFields(Message* message1,
+                          Message* message2,
+                          const std::vector<const FieldDescriptor*>& fields)
+      const = 0;
+
+  // Swap two elements of a repeated field.
+  virtual void SwapElements(Message* message,
+                            const FieldDescriptor* field,
+                            int index1,
+                            int index2) const = 0;
+
+  // List all fields of the message which are currently set.  This includes
+  // extensions.  Singular fields will only be listed if HasField(field) would
+  // return true and repeated fields will only be listed if FieldSize(field)
+  // would return non-zero.  Fields (both normal fields and extension fields)
+  // will be listed ordered by field number.
+  virtual void ListFields(
+      const Message& message,
+      std::vector<const FieldDescriptor*>* output) const = 0;
+
+  // Singular field getters ------------------------------------------
+  // These get the value of a non-repeated field.  They return the default
+  // value for fields that aren't set.
+
+  virtual int32  GetInt32 (const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual int64  GetInt64 (const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual uint32 GetUInt32(const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual uint64 GetUInt64(const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual float  GetFloat (const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual double GetDouble(const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual bool   GetBool  (const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual string GetString(const Message& message,
+                           const FieldDescriptor* field) const = 0;
+  virtual const EnumValueDescriptor* GetEnum(
+      const Message& message, const FieldDescriptor* field) const = 0;
+
+  // GetEnumValue() returns an enum field's value as an integer rather than
+  // an EnumValueDescriptor*. If the integer value does not correspond to a
+  // known value descriptor, a new value descriptor is created. (Such a value
+  // will only be present when the new unknown-enum-value semantics are enabled
+  // for a message.)
+  virtual int GetEnumValue(
+      const Message& message, const FieldDescriptor* field) const;
+
+  // See MutableMessage() for the meaning of the "factory" parameter.
+  virtual const Message& GetMessage(const Message& message,
+                                    const FieldDescriptor* field,
+                                    MessageFactory* factory = NULL) const = 0;
+
+  // Get a string value without copying, if possible.
+  //
+  // GetString() necessarily returns a copy of the string.  This can be
+  // inefficient when the string is already stored in a string object in the
+  // underlying message.  GetStringReference() will return a reference to the
+  // underlying string in this case.  Otherwise, it will copy the string into
+  // *scratch and return that.
+  //
+  // Note:  It is perfectly reasonable and useful to write code like:
+  //     str = reflection->GetStringReference(field, &str);
+  //   This line would ensure that only one copy of the string is made
+  //   regardless of the field's underlying representation.  When initializing
+  //   a newly-constructed string, though, it's just as fast and more readable
+  //   to use code like:
+  //     string str = reflection->GetString(message, field);
+  virtual const string& GetStringReference(const Message& message,
+                                           const FieldDescriptor* field,
+                                           string* scratch) const = 0;
+
+
+  // Singular field mutators -----------------------------------------
+  // These mutate the value of a non-repeated field.
+
+  virtual void SetInt32 (Message* message,
+                         const FieldDescriptor* field, int32  value) const = 0;
+  virtual void SetInt64 (Message* message,
+                         const FieldDescriptor* field, int64  value) const = 0;
+  virtual void SetUInt32(Message* message,
+                         const FieldDescriptor* field, uint32 value) const = 0;
+  virtual void SetUInt64(Message* message,
+                         const FieldDescriptor* field, uint64 value) const = 0;
+  virtual void SetFloat (Message* message,
+                         const FieldDescriptor* field, float  value) const = 0;
+  virtual void SetDouble(Message* message,
+                         const FieldDescriptor* field, double value) const = 0;
+  virtual void SetBool  (Message* message,
+                         const FieldDescriptor* field, bool   value) const = 0;
+  virtual void SetString(Message* message,
+                         const FieldDescriptor* field,
+                         const string& value) const = 0;
+  virtual void SetEnum  (Message* message,
+                         const FieldDescriptor* field,
+                         const EnumValueDescriptor* value) const = 0;
+  // Set an enum field's value with an integer rather than EnumValueDescriptor.
+  // If the value does not correspond to a known enum value, either behavior is
+  // undefined (for proto2 messages), or the value is accepted silently for
+  // messages with new unknown-enum-value semantics.
+  virtual void SetEnumValue(Message* message,
+                            const FieldDescriptor* field,
+                            int value) const;
+
+  // Get a mutable pointer to a field with a message type.  If a MessageFactory
+  // is provided, it will be used to construct instances of the sub-message;
+  // otherwise, the default factory is used.  If the field is an extension that
+  // does not live in the same pool as the containing message's descriptor (e.g.
+  // it lives in an overlay pool), then a MessageFactory must be provided.
+  // If you have no idea what that meant, then you probably don't need to worry
+  // about it (don't provide a MessageFactory).  WARNING:  If the
+  // FieldDescriptor is for a compiled-in extension, then
+  // factory->GetPrototype(field->message_type() MUST return an instance of the
+  // compiled-in class for this type, NOT DynamicMessage.
+  virtual Message* MutableMessage(Message* message,
+                                  const FieldDescriptor* field,
+                                  MessageFactory* factory = NULL) const = 0;
+  // Replaces the message specified by 'field' with the already-allocated object
+  // sub_message, passing ownership to the message.  If the field contained a
+  // message, that message is deleted.  If sub_message is NULL, the field is
+  // cleared.
+  virtual void SetAllocatedMessage(Message* message,
+                                   Message* sub_message,
+                                   const FieldDescriptor* field) const = 0;
+  // Releases the message specified by 'field' and returns the pointer,
+  // ReleaseMessage() will return the message the message object if it exists.
+  // Otherwise, it may or may not return NULL.  In any case, if the return value
+  // is non-NULL, the caller takes ownership of the pointer.
+  // If the field existed (HasField() is true), then the returned pointer will
+  // be the same as the pointer returned by MutableMessage().
+  // This function has the same effect as ClearField().
+  virtual Message* ReleaseMessage(Message* message,
+                                  const FieldDescriptor* field,
+                                  MessageFactory* factory = NULL) const = 0;
+
+
+  // Repeated field getters ------------------------------------------
+  // These get the value of one element of a repeated field.
+
+  virtual int32  GetRepeatedInt32 (const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual int64  GetRepeatedInt64 (const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual uint32 GetRepeatedUInt32(const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual uint64 GetRepeatedUInt64(const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual float  GetRepeatedFloat (const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual double GetRepeatedDouble(const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual bool   GetRepeatedBool  (const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual string GetRepeatedString(const Message& message,
+                                   const FieldDescriptor* field,
+                                   int index) const = 0;
+  virtual const EnumValueDescriptor* GetRepeatedEnum(
+      const Message& message,
+      const FieldDescriptor* field, int index) const = 0;
+  // GetRepeatedEnumValue() returns an enum field's value as an integer rather
+  // than an EnumValueDescriptor*. If the integer value does not correspond to a
+  // known value descriptor, a new value descriptor is created. (Such a value
+  // will only be present when the new unknown-enum-value semantics are enabled
+  // for a message.)
+  virtual int GetRepeatedEnumValue(
+      const Message& message,
+      const FieldDescriptor* field, int index) const;
+  virtual const Message& GetRepeatedMessage(
+      const Message& message,
+      const FieldDescriptor* field, int index) const = 0;
+
+  // See GetStringReference(), above.
+  virtual const string& GetRepeatedStringReference(
+      const Message& message, const FieldDescriptor* field,
+      int index, string* scratch) const = 0;
+
+
+  // Repeated field mutators -----------------------------------------
+  // These mutate the value of one element of a repeated field.
+
+  virtual void SetRepeatedInt32 (Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, int32  value) const = 0;
+  virtual void SetRepeatedInt64 (Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, int64  value) const = 0;
+  virtual void SetRepeatedUInt32(Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, uint32 value) const = 0;
+  virtual void SetRepeatedUInt64(Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, uint64 value) const = 0;
+  virtual void SetRepeatedFloat (Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, float  value) const = 0;
+  virtual void SetRepeatedDouble(Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, double value) const = 0;
+  virtual void SetRepeatedBool  (Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, bool   value) const = 0;
+  virtual void SetRepeatedString(Message* message,
+                                 const FieldDescriptor* field,
+                                 int index, const string& value) const = 0;
+  virtual void SetRepeatedEnum(Message* message,
+                               const FieldDescriptor* field, int index,
+                               const EnumValueDescriptor* value) const = 0;
+  // Set an enum field's value with an integer rather than EnumValueDescriptor.
+  // If the value does not correspond to a known enum value, either behavior is
+  // undefined (for proto2 messages), or the value is accepted silently for
+  // messages with new unknown-enum-value semantics.
+  virtual void SetRepeatedEnumValue(Message* message,
+                                    const FieldDescriptor* field, int index,
+                                    int value) const;
+  // Get a mutable pointer to an element of a repeated field with a message
+  // type.
+  virtual Message* MutableRepeatedMessage(
+      Message* message, const FieldDescriptor* field, int index) const = 0;
+
+
+  // Repeated field adders -------------------------------------------
+  // These add an element to a repeated field.
+
+  virtual void AddInt32 (Message* message,
+                         const FieldDescriptor* field, int32  value) const = 0;
+  virtual void AddInt64 (Message* message,
+                         const FieldDescriptor* field, int64  value) const = 0;
+  virtual void AddUInt32(Message* message,
+                         const FieldDescriptor* field, uint32 value) const = 0;
+  virtual void AddUInt64(Message* message,
+                         const FieldDescriptor* field, uint64 value) const = 0;
+  virtual void AddFloat (Message* message,
+                         const FieldDescriptor* field, float  value) const = 0;
+  virtual void AddDouble(Message* message,
+                         const FieldDescriptor* field, double value) const = 0;
+  virtual void AddBool  (Message* message,
+                         const FieldDescriptor* field, bool   value) const = 0;
+  virtual void AddString(Message* message,
+                         const FieldDescriptor* field,
+                         const string& value) const = 0;
+  virtual void AddEnum  (Message* message,
+                         const FieldDescriptor* field,
+                         const EnumValueDescriptor* value) const = 0;
+  // Set an enum field's value with an integer rather than EnumValueDescriptor.
+  // If the value does not correspond to a known enum value, either behavior is
+  // undefined (for proto2 messages), or the value is accepted silently for
+  // messages with new unknown-enum-value semantics.
+  virtual void AddEnumValue(Message* message,
+                            const FieldDescriptor* field,
+                            int value) const;
+  // See MutableMessage() for comments on the "factory" parameter.
+  virtual Message* AddMessage(Message* message,
+                              const FieldDescriptor* field,
+                              MessageFactory* factory = NULL) const = 0;
+
+  // Appends an already-allocated object 'new_entry' to the repeated field
+  // specifyed by 'field' passing ownership to the message.
+  // TODO(tmarek): Make virtual after all subclasses have been
+  // updated.
+  virtual void AddAllocatedMessage(Message* /* message */,
+                                   const FieldDescriptor* /*field */,
+                                   Message* /* new_entry */) const {}
+
+
+  // Get a RepeatedFieldRef object that can be used to read the underlying
+  // repeated field. The type parameter T must be set according to the
+  // field's cpp type. The following table shows the mapping from cpp type
+  // to acceptable T.
+  //
+  //   field->cpp_type()      T
+  //   CPPTYPE_INT32        int32
+  //   CPPTYPE_UINT32       uint32
+  //   CPPTYPE_INT64        int64
+  //   CPPTYPE_UINT64       uint64
+  //   CPPTYPE_DOUBLE       double
+  //   CPPTYPE_FLOAT        float
+  //   CPPTYPE_BOOL         bool
+  //   CPPTYPE_ENUM         generated enum type or int32
+  //   CPPTYPE_STRING       string
+  //   CPPTYPE_MESSAGE      generated message type or google::protobuf::Message
+  //
+  // A RepeatedFieldRef object can be copied and the resulted object will point
+  // to the same repeated field in the same message. The object can be used as
+  // long as the message is not destroyed.
+  //
+  // Note that to use this method users need to include the header file
+  // "google/protobuf/reflection.h" (which defines the RepeatedFieldRef
+  // class templates).
+  template<typename T>
+  RepeatedFieldRef<T> GetRepeatedFieldRef(
+      const Message& message, const FieldDescriptor* field) const;
+
+  // Like GetRepeatedFieldRef() but return an object that can also be used
+  // manipulate the underlying repeated field.
+  template<typename T>
+  MutableRepeatedFieldRef<T> GetMutableRepeatedFieldRef(
+      Message* message, const FieldDescriptor* field) const;
+
+  // DEPRECATED. Please use Get(Mutable)RepeatedFieldRef() for repeated field
+  // access. The following repeated field accesors will be removed in the
+  // future.
+  //
+  // Repeated field accessors  -------------------------------------------------
+  // The methods above, e.g. GetRepeatedInt32(msg, fd, index), provide singular
+  // access to the data in a RepeatedField.  The methods below provide aggregate
+  // access by exposing the RepeatedField object itself with the Message.
+  // Applying these templates to inappropriate types will lead to an undefined
+  // reference at link time (e.g. GetRepeatedField<***double>), or possibly a
+  // template matching error at compile time (e.g. GetRepeatedPtrField<File>).
+  //
+  // Usage example: my_doubs = refl->GetRepeatedField<double>(msg, fd);
+
+  // DEPRECATED. Please use GetRepeatedFieldRef().
+  //
+  // for T = Cord and all protobuf scalar types except enums.
+  template<typename T>
+  const RepeatedField<T>& GetRepeatedField(
+      const Message&, const FieldDescriptor*) const;
+
+  // DEPRECATED. Please use GetMutableRepeatedFieldRef().
+  //
+  // for T = Cord and all protobuf scalar types except enums.
+  template<typename T>
+  RepeatedField<T>* MutableRepeatedField(
+      Message*, const FieldDescriptor*) const;
+
+  // DEPRECATED. Please use GetRepeatedFieldRef().
+  //
+  // for T = string, google::protobuf::internal::StringPieceField
+  //         google::protobuf::Message & descendants.
+  template<typename T>
+  const RepeatedPtrField<T>& GetRepeatedPtrField(
+      const Message&, const FieldDescriptor*) const;
+
+  // DEPRECATED. Please use GetMutableRepeatedFieldRef().
+  //
+  // for T = string, google::protobuf::internal::StringPieceField
+  //         google::protobuf::Message & descendants.
+  template<typename T>
+  RepeatedPtrField<T>* MutableRepeatedPtrField(
+      Message*, const FieldDescriptor*) const;
+
+  // Extensions ----------------------------------------------------------------
+
+  // Try to find an extension of this message type by fully-qualified field
+  // name.  Returns NULL if no extension is known for this name or number.
+  virtual const FieldDescriptor* FindKnownExtensionByName(
+      const string& name) const = 0;
+
+  // Try to find an extension of this message type by field number.
+  // Returns NULL if no extension is known for this name or number.
+  virtual const FieldDescriptor* FindKnownExtensionByNumber(
+      int number) const = 0;
+
+  // Feature Flags -------------------------------------------------------------
+
+  // Does this message support storing arbitrary integer values in enum fields?
+  // If |true|, GetEnumValue/SetEnumValue and associated repeated-field versions
+  // take arbitrary integer values, and the legacy GetEnum() getter will
+  // dynamically create an EnumValueDescriptor for any integer value without
+  // one. If |false|, setting an unknown enum value via the integer-based
+  // setters results in undefined behavior (in practice, GOOGLE_DCHECK-fails).
+  //
+  // Generic code that uses reflection to handle messages with enum fields
+  // should check this flag before using the integer-based setter, and either
+  // downgrade to a compatible value or use the UnknownFieldSet if not. For
+  // example:
+  //
+  // int new_value = GetValueFromApplicationLogic();
+  // if (reflection->SupportsUnknownEnumValues()) {
+  //     reflection->SetEnumValue(message, field, new_value);
+  // } else {
+  //     if (field_descriptor->enum_type()->
+  //             FindValueByNumver(new_value) != NULL) {
+  //         reflection->SetEnumValue(message, field, new_value);
+  //     } else if (emit_unknown_enum_values) {
+  //         reflection->MutableUnknownFields(message)->AddVarint(
+  //             field->number(),
+  //             new_value);
+  //     } else {
+  //         // convert value to a compatible/default value.
+  //         new_value = CompatibleDowngrade(new_value);
+  //         reflection->SetEnumValue(message, field, new_value);
+  //     }
+  // }
+  virtual bool SupportsUnknownEnumValues() const { return false; }
+
+  // Returns the MessageFactory associated with this message.  This can be
+  // useful for determining if a message is a generated message or not, for
+  // example:
+  //
+  // if (message->GetReflection()->GetMessageFactory() ==
+  //     google::protobuf::MessageFactory::generated_factory()) {
+  //   // This is a generated message.
+  // }
+  //
+  // It can also be used to create more messages of this type, though
+  // Message::New() is an easier way to accomplish this.
+  virtual MessageFactory* GetMessageFactory() const;
+
+  // ---------------------------------------------------------------------------
+
+ protected:
+  // Obtain a pointer to a Repeated Field Structure and do some type checking:
+  //   on field->cpp_type(),
+  //   on field->field_option().ctype() (if ctype >= 0)
+  //   of field->message_type() (if message_type != NULL).
+  // We use 2 routine rather than 4 (const vs mutable) x (scalar vs pointer).
+  virtual void* MutableRawRepeatedField(
+      Message* message, const FieldDescriptor* field, FieldDescriptor::CppType,
+      int ctype, const Descriptor* message_type) const = 0;
+
+  // TODO(jieluo) - make it pure virtual after updating all the subclasses.
+  virtual const void* GetRawRepeatedField(
+      const Message& message, const FieldDescriptor* field,
+      FieldDescriptor::CppType cpptype, int ctype,
+      const Descriptor* message_type) const {
+    return MutableRawRepeatedField(
+        const_cast<Message*>(&message), field, cpptype, ctype, message_type);
+  }
+
+  // The following methods are used to implement (Mutable)RepeatedFieldRef.
+  // A Ref object will store a raw pointer to the repeated field data (obtained
+  // from RepeatedFieldData()) and a pointer to a Accessor (obtained from
+  // RepeatedFieldAccessor) which will be used to access the raw data.
+  //
+  // TODO(xiaofeng): Make these methods pure-virtual.
+
+  // Returns a raw pointer to the repeated field
+  //
+  // "cpp_type" and "message_type" are decuded from the type parameter T passed
+  // to Get(Mutable)RepeatedFieldRef. If T is a generated message type,
+  // "message_type" should be set to its descriptor. Otherwise "message_type"
+  // should be set to NULL. Implementations of this method should check whether
+  // "cpp_type"/"message_type" is consistent with the actual type of the field.
+  // We use 1 routine rather than 2 (const vs mutable) because it is protected
+  // and it doesn't change the message.
+  virtual void* RepeatedFieldData(
+      Message* message, const FieldDescriptor* field,
+      FieldDescriptor::CppType cpp_type,
+      const Descriptor* message_type) const;
+
+  // The returned pointer should point to a singleton instance which implements
+  // the RepeatedFieldAccessor interface.
+  virtual const internal::RepeatedFieldAccessor* RepeatedFieldAccessor(
+      const FieldDescriptor* field) const;
+
+ private:
+  template<typename T, typename Enable>
+  friend class RepeatedFieldRef;
+  template<typename T, typename Enable>
+  friend class MutableRepeatedFieldRef;
+  friend class ::google::protobuf::python::MapReflectionFriend;
+
+  // Special version for specialized implementations of string.  We can't call
+  // MutableRawRepeatedField directly here because we don't have access to
+  // FieldOptions::* which are defined in descriptor.pb.h.  Including that
+  // file here is not possible because it would cause a circular include cycle.
+  // We use 1 routine rather than 2 (const vs mutable) because it is private
+  // and mutable a repeated string field doesn't change the message.
+  void* MutableRawRepeatedString(
+      Message* message, const FieldDescriptor* field, bool is_string) const;
+
+  friend class MapReflectionTester;
+  // TODO(jieluo) - make the map APIs pure virtual after updating
+  // all the subclasses.
+  // Returns true if key is in map. Returns false if key is not in map field.
+  virtual bool ContainsMapKey(const Message& /* message*/,
+                              const FieldDescriptor* /* field */,
+                              const MapKey& /* key */) const {
+    return false;
+  }
+
+  // If key is in map field: Saves the value pointer to val and returns
+  // false. If key in not in map field: Insert the key into map, saves
+  // value pointer to val and retuns true.
+  virtual bool InsertOrLookupMapValue(Message* /* message */,
+                                      const FieldDescriptor* /* field */,
+                                      const MapKey& /* key */,
+                                      MapValueRef* /* val */) const {
+    return false;
+  }
+
+  // Delete and returns true if key is in the map field. Returns false
+  // otherwise.
+  virtual bool DeleteMapValue(Message* /* mesage */,
+                              const FieldDescriptor* /* field */,
+                              const MapKey& /* key */) const {
+    return false;
+  }
+
+  // Returns a MapIterator referring to the first element in the map field.
+  // If the map field is empty, this function returns the same as
+  // reflection::MapEnd. Mutation to the field may invalidate the iterator.
+  virtual MapIterator MapBegin(
+      Message* message,
+      const FieldDescriptor* field) const;
+
+  // Returns a MapIterator referring to the theoretical element that would
+  // follow the last element in the map field. It does not point to any
+  // real element. Mutation to the field may invalidate the iterator.
+  virtual MapIterator MapEnd(
+      Message* message,
+      const FieldDescriptor* field) const;
+
+  // Get the number of <key, value> pair of a map field. The result may be
+  // different from FieldSize which can have duplicate keys.
+  virtual int MapSize(const Message& /* message */,
+                      const FieldDescriptor* /* field */) const {
+    return 0;
+  }
+
+  // Help method for MapIterator.
+  friend class MapIterator;
+  virtual internal::MapFieldBase* MapData(
+      Message* /* message */, const FieldDescriptor* /* field */) const {
+    return NULL;
+  }
+
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Reflection);
+};
+
+// Abstract interface for a factory for message objects.
+class LIBPROTOBUF_EXPORT MessageFactory {
+ public:
+  inline MessageFactory() {}
+  virtual ~MessageFactory();
+
+  // Given a Descriptor, gets or constructs the default (prototype) Message
+  // of that type.  You can then call that message's New() method to construct
+  // a mutable message of that type.
+  //
+  // Calling this method twice with the same Descriptor returns the same
+  // object.  The returned object remains property of the factory.  Also, any
+  // objects created by calling the prototype's New() method share some data
+  // with the prototype, so these must be destroyed before the MessageFactory
+  // is destroyed.
+  //
+  // The given descriptor must outlive the returned message, and hence must
+  // outlive the MessageFactory.
+  //
+  // Some implementations do not support all types.  GetPrototype() will
+  // return NULL if the descriptor passed in is not supported.
+  //
+  // This method may or may not be thread-safe depending on the implementation.
+  // Each implementation should document its own degree thread-safety.
+  virtual const Message* GetPrototype(const Descriptor* type) = 0;
+
+  // Gets a MessageFactory which supports all generated, compiled-in messages.
+  // In other words, for any compiled-in type FooMessage, the following is true:
+  //   MessageFactory::generated_factory()->GetPrototype(
+  //     FooMessage::descriptor()) == FooMessage::default_instance()
+  // This factory supports all types which are found in
+  // DescriptorPool::generated_pool().  If given a descriptor from any other
+  // pool, GetPrototype() will return NULL.  (You can also check if a
+  // descriptor is for a generated message by checking if
+  // descriptor->file()->pool() == DescriptorPool::generated_pool().)
+  //
+  // This factory is 100% thread-safe; calling GetPrototype() does not modify
+  // any shared data.
+  //
+  // This factory is a singleton.  The caller must not delete the object.
+  static MessageFactory* generated_factory();
+
+  // For internal use only:  Registers a .proto file at static initialization
+  // time, to be placed in generated_factory.  The first time GetPrototype()
+  // is called with a descriptor from this file, |register_messages| will be
+  // called, with the file name as the parameter.  It must call
+  // InternalRegisterGeneratedMessage() (below) to register each message type
+  // in the file.  This strange mechanism is necessary because descriptors are
+  // built lazily, so we can't register types by their descriptor until we
+  // know that the descriptor exists.  |filename| must be a permanent string.
+  static void InternalRegisterGeneratedFile(
+      const char* filename, void (*register_messages)(const string&));
+
+  // For internal use only:  Registers a message type.  Called only by the
+  // functions which are registered with InternalRegisterGeneratedFile(),
+  // above.
+  static void InternalRegisterGeneratedMessage(const Descriptor* descriptor,
+                                               const Message* prototype);
+
+
+ private:
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageFactory);
+};
+
+#define DECLARE_GET_REPEATED_FIELD(TYPE)                         \
+template<>                                                       \
+LIBPROTOBUF_EXPORT                                               \
+const RepeatedField<TYPE>& Reflection::GetRepeatedField<TYPE>(   \
+    const Message& message, const FieldDescriptor* field) const; \
+                                                                 \
+template<>                                                       \
+LIBPROTOBUF_EXPORT                                               \
+RepeatedField<TYPE>* Reflection::MutableRepeatedField<TYPE>(     \
+    Message* message, const FieldDescriptor* field) const;
+
+DECLARE_GET_REPEATED_FIELD(int32)
+DECLARE_GET_REPEATED_FIELD(int64)
+DECLARE_GET_REPEATED_FIELD(uint32)
+DECLARE_GET_REPEATED_FIELD(uint64)
+DECLARE_GET_REPEATED_FIELD(float)
+DECLARE_GET_REPEATED_FIELD(double)
+DECLARE_GET_REPEATED_FIELD(bool)
+
+#undef DECLARE_GET_REPEATED_FIELD
+
+// =============================================================================
+// Implementation details for {Get,Mutable}RawRepeatedPtrField.  We provide
+// specializations for <string>, <StringPieceField> and <Message> and handle
+// everything else with the default template which will match any type having
+// a method with signature "static const google::protobuf::Descriptor* descriptor()".
+// Such a type presumably is a descendant of google::protobuf::Message.
+
+template<>
+inline const RepeatedPtrField<string>& Reflection::GetRepeatedPtrField<string>(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<RepeatedPtrField<string>* >(
+      MutableRawRepeatedString(const_cast<Message*>(&message), field, true));
+}
+
+template<>
+inline RepeatedPtrField<string>* Reflection::MutableRepeatedPtrField<string>(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<string>* >(
+      MutableRawRepeatedString(message, field, true));
+}
+
+
+// -----
+
+template<>
+inline const RepeatedPtrField<Message>& Reflection::GetRepeatedPtrField(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<const RepeatedPtrField<Message>* >(
+      GetRawRepeatedField(message, field, FieldDescriptor::CPPTYPE_MESSAGE,
+                          -1, NULL));
+}
+
+template<>
+inline RepeatedPtrField<Message>* Reflection::MutableRepeatedPtrField(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<Message>* >(
+      MutableRawRepeatedField(message, field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          NULL));
+}
+
+template<typename PB>
+inline const RepeatedPtrField<PB>& Reflection::GetRepeatedPtrField(
+    const Message& message, const FieldDescriptor* field) const {
+  return *static_cast<const RepeatedPtrField<PB>* >(
+      GetRawRepeatedField(message, field, FieldDescriptor::CPPTYPE_MESSAGE,
+                          -1, PB::default_instance().GetDescriptor()));
+}
+
+template<typename PB>
+inline RepeatedPtrField<PB>* Reflection::MutableRepeatedPtrField(
+    Message* message, const FieldDescriptor* field) const {
+  return static_cast<RepeatedPtrField<PB>* >(
+      MutableRawRepeatedField(message, field,
+          FieldDescriptor::CPPTYPE_MESSAGE, -1,
+          PB::default_instance().GetDescriptor()));
+}
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_MESSAGE_H__