repeated_field.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: [email protected] (Kenton Varda)
// Based on original Protocol Buffers design by
// Sanjay Ghemawat, Jeff Dean, and others.
//
// RepeatedField and RepeatedPtrField are used by generated protocol message
// classes to manipulate repeated fields. These classes are very similar to
// STL's vector, but include a number of optimizations found to be useful
// specifically in the case of Protocol Buffers. RepeatedPtrField is
// particularly different from STL vector as it manages ownership of the
// pointers that it contains.
//
// Typically, clients should not need to access RepeatedField objects directly,
// but should instead use the accessor functions generated automatically by the
// protocol compiler.

#ifndef GOOGLE_PROTOBUF_REPEATED_FIELD_H__
#define GOOGLE_PROTOBUF_REPEATED_FIELD_H__

#ifdef _MSC_VER
// This is required for min/max on VS2013 only.
#include <algorithm>
#endif

#include <string>
#include <iterator>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/type_traits.h>
#include <google/protobuf/generated_message_util.h>
#include <google/protobuf/message_lite.h>

namespace google {

namespace upb {
namespace google_opensource {
class GMR_Handlers;
} // namespace google_opensource
} // namespace upb

namespace protobuf {

class Message;

namespace internal {

static const int kMinRepeatedFieldAllocationSize = 4;

// A utility function for logging that doesn't need any template types.
void LogIndexOutOfBounds(int index, int size);

template <typename Iter>
inline int CalculateReserve(Iter begin, Iter end, std::forward_iterator_tag) {
 return std::distance(begin, end);
}

template <typename Iter>
inline int CalculateReserve(Iter /*begin*/, Iter /*end*/, std::input_iterator_tag) {
 return -1;
}

template <typename Iter>
inline int CalculateReserve(Iter begin, Iter end) {
 typedef typename std::iterator_traits<Iter>::iterator_category Category;
 return CalculateReserve(begin, end, Category());
}
} // namespace internal


// RepeatedField is used to represent repeated fields of a primitive type (in
// other words, everything except strings and nested Messages). Most users will
// not ever use a RepeatedField directly; they will use the get-by-index,
// set-by-index, and add accessors that are generated for all repeated fields.
template <typename Element>
class RepeatedField {
 public:
 RepeatedField();
 RepeatedField(const RepeatedField& other);
 template <typename Iter>
 RepeatedField(Iter begin, const Iter& end);
 ~RepeatedField();

 RepeatedField& operator=(const RepeatedField& other);

 bool empty() const;
 int size() const;

 const Element& Get(int index) const;
 Element* Mutable(int index);
 void Set(int index, const Element& value);
 void Add(const Element& value);
 Element* Add();
 // Remove the last element in the array.
 void RemoveLast();

 // Extract elements with indices in "[start .. start+num-1]".
 // Copy them into "elements[0 .. num-1]" if "elements" is not NULL.
 // Caution: implementation also moves elements with indices [start+num ..].
 // Calling this routine inside a loop can cause quadratic behavior.
 void ExtractSubrange(int start, int num, Element* elements);

 void Clear();
 void MergeFrom(const RepeatedField& other);
 void CopyFrom(const RepeatedField& other);

 // Reserve space to expand the field to at least the given size. If the
 // array is grown, it will always be at least doubled in size.
 void Reserve(int new_size);

 // Resize the RepeatedField to a new, smaller size. This is O(1).
 void Truncate(int new_size);

 void AddAlreadyReserved(const Element& value);
 Element* AddAlreadyReserved();
 int Capacity() const;

 // Like STL resize. Uses value to fill appended elements.
 // Like Truncate() if new_size <= size(), otherwise this is
 // O(new_size - size()).
 void Resize(int new_size, const Element& value);

 // Gets the underlying array. This pointer is possibly invalidated by
 // any add or remove operation.
 Element* mutable_data();
 const Element* data() const;

 // Swap entire contents with "other".
 void Swap(RepeatedField* other);

 // Swap two elements.
 void SwapElements(int index1, int index2);

 // STL-like iterator support
 typedef Element* iterator;
 typedef const Element* const_iterator;
 typedef Element value_type;
 typedef value_type& reference;
 typedef const value_type& const_reference;
 typedef value_type* pointer;
 typedef const value_type* const_pointer;
 typedef int size_type;
 typedef ptrdiff_t difference_type;

 iterator begin();
 const_iterator begin() const;
 iterator end();
 const_iterator end() const;

 // Reverse iterator support
 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
 typedef std::reverse_iterator<iterator> reverse_iterator;
 reverse_iterator rbegin() {
 return reverse_iterator(end());
 }
 const_reverse_iterator rbegin() const {
 return const_reverse_iterator(end());
 }
 reverse_iterator rend() {
 return reverse_iterator(begin());
 }
 const_reverse_iterator rend() const {
 return const_reverse_iterator(begin());
 }

 // Returns the number of bytes used by the repeated field, excluding
 // sizeof(*this)
 int SpaceUsedExcludingSelf() const;

 private:
 static const int kInitialSize = 0;

 Element* elements_;
 int current_size_;
 int total_size_;

 // Move the contents of |from| into |to|, possibly clobbering |from| in the
 // process. For primitive types this is just a memcpy(), but it could be
 // specialized for non-primitive types to, say, swap each element instead.
 void MoveArray(Element to[], Element from[], int size);

 // Copy the elements of |from| into |to|.
 void CopyArray(Element to[], const Element from[], int size);
};

namespace internal {
template <typename It> class RepeatedPtrIterator;
template <typename It, typename VoidPtr> class RepeatedPtrOverPtrsIterator;
} // namespace internal

namespace internal {

// This is a helper template to copy an array of elements effeciently when they
// have a trivial copy constructor, and correctly otherwise. This really
// shouldn't be necessary, but our compiler doesn't optimize std::copy very
// effectively.
template <typename Element,
 bool HasTrivialCopy = has_trivial_copy<Element>::value>
struct ElementCopier {
 void operator()(Element to[], const Element from[], int array_size);
};

} // namespace internal

namespace internal {

// This is the common base class for RepeatedPtrFields. It deals only in void*
// pointers. Users should not use this interface directly.
//
// The methods of this interface correspond to the methods of RepeatedPtrField,
// but may have a template argument called TypeHandler. Its signature is:
// class TypeHandler {
// public:
// typedef MyType Type;
// static Type* New();
// static void Delete(Type*);
// static void Clear(Type*);
// static void Merge(const Type& from, Type* to);
//
// // Only needs to be implemented if SpaceUsedExcludingSelf() is called.
// static int SpaceUsed(const Type&);
// };
class LIBPROTOBUF_EXPORT RepeatedPtrFieldBase {
 protected:
 // The reflection implementation needs to call protected methods directly,
 // reinterpreting pointers as being to Message instead of a specific Message
 // subclass.
 friend class GeneratedMessageReflection;

 // ExtensionSet stores repeated message extensions as
 // RepeatedPtrField<MessageLite>, but non-lite ExtensionSets need to
 // implement SpaceUsed(), and thus need to call SpaceUsedExcludingSelf()
 // reinterpreting MessageLite as Message. ExtensionSet also needs to make
 // use of AddFromCleared(), which is not part of the public interface.
 friend class ExtensionSet;

 // To parse directly into a proto2 generated class, the upb class GMR_Handlers
 // needs to be able to modify a RepeatedPtrFieldBase directly.
 friend class LIBPROTOBUF_EXPORT upb::google_opensource::GMR_Handlers;

 RepeatedPtrFieldBase();

 // Must be called from destructor.
 template <typename TypeHandler>
 void Destroy();

 bool empty() const;
 int size() const;

 template <typename TypeHandler>
 const typename TypeHandler::Type& Get(int index) const;
 template <typename TypeHandler>
 typename TypeHandler::Type* Mutable(int index);
 template <typename TypeHandler>
 typename TypeHandler::Type* Add();
 template <typename TypeHandler>
 void RemoveLast();
 template <typename TypeHandler>
 void Clear();
 template <typename TypeHandler>
 void MergeFrom(const RepeatedPtrFieldBase& other);
 template <typename TypeHandler>
 void CopyFrom(const RepeatedPtrFieldBase& other);

 void CloseGap(int start, int num) {
 // Close up a gap of "num" elements starting at offset "start".
 for (int i = start + num; i < allocated_size_; ++i)
 elements_[i - num] = elements_[i];
 current_size_ -= num;
 allocated_size_ -= num;
 }

 void Reserve(int new_size);

 int Capacity() const;

 // Used for constructing iterators.
 void* const* raw_data() const;
 void** raw_mutable_data() const;

 template <typename TypeHandler>
 typename TypeHandler::Type** mutable_data();
 template <typename TypeHandler>
 const typename TypeHandler::Type* const* data() const;

 void Swap(RepeatedPtrFieldBase* other);

 void SwapElements(int index1, int index2);

 template <typename TypeHandler>
 int SpaceUsedExcludingSelf() const;


 // Advanced memory management --------------------------------------

 // Like Add(), but if there are no cleared objects to use, returns NULL.
 template <typename TypeHandler>
 typename TypeHandler::Type* AddFromCleared();

 template <typename TypeHandler>
 void AddAllocated(typename TypeHandler::Type* value);
 template <typename TypeHandler>
 typename TypeHandler::Type* ReleaseLast();

 int ClearedCount() const;
 template <typename TypeHandler>
 void AddCleared(typename TypeHandler::Type* value);
 template <typename TypeHandler>
 typename TypeHandler::Type* ReleaseCleared();

 private:
 static const int kInitialSize = 0;

 void** elements_;
 int current_size_;
 int allocated_size_;
 int total_size_;

 template <typename TypeHandler>
 static inline typename TypeHandler::Type* cast(void* element) {
 return reinterpret_cast<typename TypeHandler::Type*>(element);
 }
 template <typename TypeHandler>
 static inline const typename TypeHandler::Type* cast(const void* element) {
 return reinterpret_cast<const typename TypeHandler::Type*>(element);
 }

 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(RepeatedPtrFieldBase);
};

template <typename GenericType>
class GenericTypeHandler {
 public:
 typedef GenericType Type;
 static GenericType* New() { return new GenericType; }
 static void Delete(GenericType* value) { delete value; }
 static void Clear(GenericType* value) { value->Clear(); }
 static void Merge(const GenericType& from, GenericType* to) {
 to->MergeFrom(from);
 }
 static int SpaceUsed(const GenericType& value) { return value.SpaceUsed(); }
 static const Type& default_instance() { return Type::default_instance(); }
};

template <>
inline void GenericTypeHandler<MessageLite>::Merge(
 const MessageLite& from, MessageLite* to) {
 to->CheckTypeAndMergeFrom(from);
}

template <>
inline const MessageLite& GenericTypeHandler<MessageLite>::default_instance() {
 // Yes, the behavior of the code is undefined, but this function is only
 // called when we're already deep into the world of undefined, because the
 // caller called Get(index) out of bounds.
 MessageLite* null = NULL;
 return *null;
}

template <>
inline const Message& GenericTypeHandler<Message>::default_instance() {
 // Yes, the behavior of the code is undefined, but this function is only
 // called when we're already deep into the world of undefined, because the
 // caller called Get(index) out of bounds.
 Message* null = NULL;
 return *null;
}


// HACK: If a class is declared as DLL-exported in MSVC, it insists on
// generating copies of all its methods -- even inline ones -- to include
// in the DLL. But SpaceUsed() calls StringSpaceUsedExcludingSelf() which
// isn't in the lite library, therefore the lite library cannot link if
// StringTypeHandler is exported. So, we factor out StringTypeHandlerBase,
// export that, then make StringTypeHandler be a subclass which is NOT
// exported.
// TODO(kenton): There has to be a better way.
class LIBPROTOBUF_EXPORT StringTypeHandlerBase {
 public:
 typedef string Type;
 static string* New();
 static void Delete(string* value);
 static void Clear(string* value) { value->clear(); }
 static void Merge(const string& from, string* to) { *to = from; }
 static const Type& default_instance() {
 return ::google::protobuf::internal::GetEmptyString();
 }
};

class StringTypeHandler : public StringTypeHandlerBase {
 public:
 static int SpaceUsed(const string& value) {
 return sizeof(value) + StringSpaceUsedExcludingSelf(value);
 }
};


} // namespace internal

// RepeatedPtrField is like RepeatedField, but used for repeated strings or
// Messages.
template <typename Element>
class RepeatedPtrField : public internal::RepeatedPtrFieldBase {
 public:
 RepeatedPtrField();
 RepeatedPtrField(const RepeatedPtrField& other);
 template <typename Iter>
 RepeatedPtrField(Iter begin, const Iter& end);
 ~RepeatedPtrField();

 RepeatedPtrField& operator=(const RepeatedPtrField& other);

 bool empty() const;
 int size() const;

 const Element& Get(int index) const;
 Element* Mutable(int index);
 Element* Add();

 // Remove the last element in the array.
 // Ownership of the element is retained by the array.
 void RemoveLast();

 // Delete elements with indices in the range [start .. start+num-1].
 // Caution: implementation moves all elements with indices [start+num .. ].
 // Calling this routine inside a loop can cause quadratic behavior.
 void DeleteSubrange(int start, int num);

 void Clear();
 void MergeFrom(const RepeatedPtrField& other);
 void CopyFrom(const RepeatedPtrField& other);

 // Reserve space to expand the field to at least the given size. This only
 // resizes the pointer array; it doesn't allocate any objects. If the
 // array is grown, it will always be at least doubled in size.
 void Reserve(int new_size);

 int Capacity() const;

 // Gets the underlying array. This pointer is possibly invalidated by
 // any add or remove operation.
 Element** mutable_data();
 const Element* const* data() const;

 // Swap entire contents with "other".
 void Swap(RepeatedPtrField* other);

 // Swap two elements.
 void SwapElements(int index1, int index2);

 // STL-like iterator support
 typedef internal::RepeatedPtrIterator<Element> iterator;
 typedef internal::RepeatedPtrIterator<const Element> const_iterator;
 typedef Element value_type;
 typedef value_type& reference;
 typedef const value_type& const_reference;
 typedef value_type* pointer;
 typedef const value_type* const_pointer;
 typedef int size_type;
 typedef ptrdiff_t difference_type;

 iterator begin();
 const_iterator begin() const;
 iterator end();
 const_iterator end() const;

 // Reverse iterator support
 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
 typedef std::reverse_iterator<iterator> reverse_iterator;
 reverse_iterator rbegin() {
 return reverse_iterator(end());
 }
 const_reverse_iterator rbegin() const {
 return const_reverse_iterator(end());
 }
 reverse_iterator rend() {
 return reverse_iterator(begin());
 }
 const_reverse_iterator rend() const {
 return const_reverse_iterator(begin());
 }

 // Custom STL-like iterator that iterates over and returns the underlying
 // pointers to Element rather than Element itself.
 typedef internal::RepeatedPtrOverPtrsIterator<Element, void*>
 pointer_iterator;
 typedef internal::RepeatedPtrOverPtrsIterator<const Element, const void*>
 const_pointer_iterator;
 pointer_iterator pointer_begin();
 const_pointer_iterator pointer_begin() const;
 pointer_iterator pointer_end();
 const_pointer_iterator pointer_end() const;

 // Returns (an estimate of) the number of bytes used by the repeated field,
 // excluding sizeof(*this).
 int SpaceUsedExcludingSelf() const;

 // Advanced memory management --------------------------------------
 // When hardcore memory management becomes necessary -- as it sometimes
 // does here at Google -- the following methods may be useful.

 // Add an already-allocated object, passing ownership to the
 // RepeatedPtrField.
 void AddAllocated(Element* value);
 // Remove the last element and return it, passing ownership to the caller.
 // Requires: size() > 0
 Element* ReleaseLast();

 // Extract elements with indices in the range "[start .. start+num-1]".
 // The caller assumes ownership of the extracted elements and is responsible
 // for deleting them when they are no longer needed.
 // If "elements" is non-NULL, then pointers to the extracted elements
 // are stored in "elements[0 .. num-1]" for the convenience of the caller.
 // If "elements" is NULL, then the caller must use some other mechanism
 // to perform any further operations (like deletion) on these elements.
 // Caution: implementation also moves elements with indices [start+num ..].
 // Calling this routine inside a loop can cause quadratic behavior.
 void ExtractSubrange(int start, int num, Element** elements);

 // When elements are removed by calls to RemoveLast() or Clear(), they
 // are not actually freed. Instead, they are cleared and kept so that
 // they can be reused later. This can save lots of CPU time when
 // repeatedly reusing a protocol message for similar purposes.
 //
 // Hardcore programs may choose to manipulate these cleared objects
 // to better optimize memory management using the following routines.

 // Get the number of cleared objects that are currently being kept
 // around for reuse.
 int ClearedCount() const;
 // Add an element to the pool of cleared objects, passing ownership to
 // the RepeatedPtrField. The element must be cleared prior to calling
 // this method.
 void AddCleared(Element* value);
 // Remove a single element from the cleared pool and return it, passing
 // ownership to the caller. The element is guaranteed to be cleared.
 // Requires: ClearedCount() > 0
 Element* ReleaseCleared();

 protected:
 // Note: RepeatedPtrField SHOULD NOT be subclassed by users. We only
 // subclass it in one place as a hack for compatibility with proto1. The
 // subclass needs to know about TypeHandler in order to call protected
 // methods on RepeatedPtrFieldBase.
 class TypeHandler;

};

// implementation ====================================================

template <typename Element>
inline RepeatedField<Element>::RepeatedField()
 : elements_(NULL),
 current_size_(0),
 total_size_(kInitialSize) {
}

template <typename Element>
inline RepeatedField<Element>::RepeatedField(const RepeatedField& other)
 : elements_(NULL),
 current_size_(0),
 total_size_(kInitialSize) {
 CopyFrom(other);
}

template <typename Element>
template <typename Iter>
inline RepeatedField<Element>::RepeatedField(Iter begin, const Iter& end)
 : elements_(NULL),
 current_size_(0),
 total_size_(kInitialSize) {
 int reserve = internal::CalculateReserve(begin, end);
 if (reserve != -1) {
 Reserve(reserve);
 for (; begin != end; ++begin) {
 AddAlreadyReserved(*begin);
 }
 } else {
 for (; begin != end; ++begin) {
 Add(*begin);
 }
 }
}

template <typename Element>
RepeatedField<Element>::~RepeatedField() {
 delete [] elements_;
}

template <typename Element>
inline RepeatedField<Element>&
RepeatedField<Element>::operator=(const RepeatedField& other) {
 if (this != &other)
 CopyFrom(other);
 return *this;
}

template <typename Element>
inline bool RepeatedField<Element>::empty() const {
 return current_size_ == 0;
}

template <typename Element>
inline int RepeatedField<Element>::size() const {
 return current_size_;
}

template <typename Element>
inline int RepeatedField<Element>::Capacity() const {
 return total_size_;
}

template<typename Element>
inline void RepeatedField<Element>::AddAlreadyReserved(const Element& value) {
 GOOGLE_DCHECK_LT(size(), Capacity());
 elements_[current_size_++] = value;
}

template<typename Element>
inline Element* RepeatedField<Element>::AddAlreadyReserved() {
 GOOGLE_DCHECK_LT(size(), Capacity());
 return &elements_[current_size_++];
}

template<typename Element>
inline void RepeatedField<Element>::Resize(int new_size, const Element& value) {
 GOOGLE_DCHECK_GE(new_size, 0);
 if (new_size > size()) {
 Reserve(new_size);
 std::fill(&elements_[current_size_], &elements_[new_size], value);
 }
 current_size_ = new_size;
}

template <typename Element>
inline const Element& RepeatedField<Element>::Get(int index) const {
 GOOGLE_DCHECK_GE(index, 0);
 GOOGLE_DCHECK_LT(index, size());
 return elements_[index];
}

template <typename Element>
inline Element* RepeatedField<Element>::Mutable(int index) {
 GOOGLE_DCHECK_GE(index, 0);
 GOOGLE_DCHECK_LT(index, size());
 return elements_ + index;
}

template <typename Element>
inline void RepeatedField<Element>::Set(int index, const Element& value) {
 GOOGLE_DCHECK_GE(index, 0);
 GOOGLE_DCHECK_LT(index, size());
 elements_[index] = value;
}

template <typename Element>
inline void RepeatedField<Element>::Add(const Element& value) {
 if (current_size_ == total_size_) Reserve(total_size_ + 1);
 elements_[current_size_++] = value;
}

template <typename Element>
inline Element* RepeatedField<Element>::Add() {
 if (current_size_ == total_size_) Reserve(total_size_ + 1);
 return &elements_[current_size_++];
}

template <typename Element>
inline void RepeatedField<Element>::RemoveLast() {
 GOOGLE_DCHECK_GT(current_size_, 0);
 --current_size_;
}

template <typename Element>
void RepeatedField<Element>::ExtractSubrange(
 int start, int num, Element* elements) {
 GOOGLE_DCHECK_GE(start, 0);
 GOOGLE_DCHECK_GE(num, 0);
 GOOGLE_DCHECK_LE(start + num, this->size());

 // Save the values of the removed elements if requested.
 if (elements != NULL) {
 for (int i = 0; i < num; ++i)
 elements[i] = this->Get(i + start);
 }

 // Slide remaining elements down to fill the gap.
 if (num > 0) {
 for (int i = start + num; i < this->size(); ++i)
 this->Set(i - num, this->Get(i));
 this->Truncate(this->size() - num);
 }
}

template <typename Element>
inline void RepeatedField<Element>::Clear() {
 current_size_ = 0;
}

template <typename Element>
inline void RepeatedField<Element>::MergeFrom(const RepeatedField& other) {
 GOOGLE_CHECK_NE(&other, this);
 if (other.current_size_ != 0) {
 Reserve(current_size_ + other.current_size_);
 CopyArray(elements_ + current_size_, other.elements_, other.current_size_);
 current_size_ += other.current_size_;
 }
}

template <typename Element>
inline void RepeatedField<Element>::CopyFrom(const RepeatedField& other) {
 if (&other == this) return;
 Clear();
 MergeFrom(other);
}

template <typename Element>
inline Element* RepeatedField<Element>::mutable_data() {
 return elements_;
}

template <typename Element>
inline const Element* RepeatedField<Element>::data() const {
 return elements_;
}


template <typename Element>
void RepeatedField<Element>::Swap(RepeatedField* other) {
 if (this == other) return;
 Element* swap_elements = elements_;
 int swap_current_size = current_size_;
 int swap_total_size = total_size_;

 elements_ = other->elements_;
 current_size_ = other->current_size_;
 total_size_ = other->total_size_;

 other->elements_ = swap_elements;
 other->current_size_ = swap_current_size;
 other->total_size_ = swap_total_size;
}

template <typename Element>
void RepeatedField<Element>::SwapElements(int index1, int index2) {
 using std::swap; // enable ADL with fallback
 swap(elements_[index1], elements_[index2]);
}

template <typename Element>
inline typename RepeatedField<Element>::iterator
RepeatedField<Element>::begin() {
 return elements_;
}
template <typename Element>
inline typename RepeatedField<Element>::const_iterator
RepeatedField<Element>::begin() const {
 return elements_;
}
template <typename Element>
inline typename RepeatedField<Element>::iterator
RepeatedField<Element>::end() {
 return elements_ + current_size_;
}
template <typename Element>
inline typename RepeatedField<Element>::const_iterator
RepeatedField<Element>::end() const {
 return elements_ + current_size_;
}

template <typename Element>
inline int RepeatedField<Element>::SpaceUsedExcludingSelf() const {
 return (elements_ != NULL) ? total_size_ * sizeof(elements_[0]) : 0;
}

// Avoid inlining of Reserve(): new, copy, and delete[] lead to a significant
// amount of code bloat.
template <typename Element>
void RepeatedField<Element>::Reserve(int new_size) {
 if (total_size_ >= new_size) return;

 Element* old_elements = elements_;
 total_size_ = max(google::protobuf::internal::kMinRepeatedFieldAllocationSize,
 max(total_size_ * 2, new_size));
 elements_ = new Element[total_size_];
 if (old_elements != NULL) {
 MoveArray(elements_, old_elements, current_size_);
 delete [] old_elements;
 }
}

template <typename Element>
inline void RepeatedField<Element>::Truncate(int new_size) {
 GOOGLE_DCHECK_LE(new_size, current_size_);
 current_size_ = new_size;
}

template <typename Element>
inline void RepeatedField<Element>::MoveArray(
 Element to[], Element from[], int array_size) {
 CopyArray(to, from, array_size);
}

template <typename Element>
inline void RepeatedField<Element>::CopyArray(
 Element to[], const Element from[], int array_size) {
 internal::ElementCopier<Element>()(to, from, array_size);
}

namespace internal {

template <typename Element, bool HasTrivialCopy>
void ElementCopier<Element, HasTrivialCopy>::operator()(
 Element to[], const Element from[], int array_size) {
 std::copy(from, from + array_size, to);
}

template <typename Element>
struct ElementCopier<Element, true> {
 void operator()(Element to[], const Element from[], int array_size) {
 memcpy(to, from, array_size * sizeof(Element));
 }
};

} // namespace internal


// -------------------------------------------------------------------

namespace internal {

inline RepeatedPtrFieldBase::RepeatedPtrFieldBase()
 : elements_(NULL),
 current_size_(0),
 allocated_size_(0),
 total_size_(kInitialSize) {
}

template <typename TypeHandler>
void RepeatedPtrFieldBase::Destroy() {
 for (int i = 0; i < allocated_size_; i++) {
 TypeHandler::Delete(cast<TypeHandler>(elements_[i]));
 }
 delete [] elements_;
}

inline bool RepeatedPtrFieldBase::empty() const {
 return current_size_ == 0;
}

inline int RepeatedPtrFieldBase::size() const {
 return current_size_;
}

template <typename TypeHandler>
inline const typename TypeHandler::Type&
RepeatedPtrFieldBase::Get(int index) const {
 GOOGLE_DCHECK_GE(index, 0);
 GOOGLE_DCHECK_LT(index, size());
 return *cast<TypeHandler>(elements_[index]);
}


template <typename TypeHandler>
inline typename TypeHandler::Type*
RepeatedPtrFieldBase::Mutable(int index) {
 GOOGLE_DCHECK_GE(index, 0);
 GOOGLE_DCHECK_LT(index, size());
 return cast<TypeHandler>(elements_[index]);
}

template <typename TypeHandler>
inline typename TypeHandler::Type* RepeatedPtrFieldBase::Add() {
 if (current_size_ < allocated_size_) {
 return cast<TypeHandler>(elements_[current_size_++]);
 }
 if (allocated_size_ == total_size_) Reserve(total_size_ + 1);
 typename TypeHandler::Type* result = TypeHandler::New();
 ++allocated_size_;
 elements_[current_size_++] = result;
 return result;
}

template <typename TypeHandler>
inline void RepeatedPtrFieldBase::RemoveLast() {
 GOOGLE_DCHECK_GT(current_size_, 0);
 TypeHandler::Clear(cast<TypeHandler>(elements_[--current_size_]));
}

template <typename TypeHandler>
void RepeatedPtrFieldBase::Clear() {
 for (int i = 0; i < current_size_; i++) {
 TypeHandler::Clear(cast<TypeHandler>(elements_[i]));
 }
 current_size_ = 0;
}

template <typename TypeHandler>
inline void RepeatedPtrFieldBase::MergeFrom(const RepeatedPtrFieldBase& other) {
 GOOGLE_CHECK_NE(&other, this);
 Reserve(current_size_ + other.current_size_);
 for (int i = 0; i < other.current_size_; i++) {
 TypeHandler::Merge(other.template Get<TypeHandler>(i), Add<TypeHandler>());
 }
}

template <typename TypeHandler>
inline void RepeatedPtrFieldBase::CopyFrom(const RepeatedPtrFieldBase& other) {
 if (&other == this) return;
 RepeatedPtrFieldBase::Clear<TypeHandler>();
 RepeatedPtrFieldBase::MergeFrom<TypeHandler>(other);
}

inline int RepeatedPtrFieldBase::Capacity() const {
 return total_size_;
}

inline void* const* RepeatedPtrFieldBase::raw_data() const {
 return elements_;
}

inline void** RepeatedPtrFieldBase::raw_mutable_data() const {
 return elements_;
}

template <typename TypeHandler>
inline typename TypeHandler::Type** RepeatedPtrFieldBase::mutable_data() {
 // TODO(kenton): Breaks C++ aliasing rules. We should probably remove this
 // method entirely.
 return reinterpret_cast<typename TypeHandler::Type**>(elements_);
}

template <typename TypeHandler>
inline const typename TypeHandler::Type* const*
RepeatedPtrFieldBase::data() const {
 // TODO(kenton): Breaks C++ aliasing rules. We should probably remove this
 // method entirely.
 return reinterpret_cast<const typename TypeHandler::Type* const*>(elements_);
}

inline void RepeatedPtrFieldBase::SwapElements(int index1, int index2) {
 using std::swap; // enable ADL with fallback
 swap(elements_[index1], elements_[index2]);
}

template <typename TypeHandler>
inline int RepeatedPtrFieldBase::SpaceUsedExcludingSelf() const {
 int allocated_bytes =
 (elements_ != NULL) ? total_size_ * sizeof(elements_[0]) : 0;
 for (int i = 0; i < allocated_size_; ++i) {
 allocated_bytes += TypeHandler::SpaceUsed(*cast<TypeHandler>(elements_[i]));
 }
 return allocated_bytes;
}

template <typename TypeHandler>
inline typename TypeHandler::Type* RepeatedPtrFieldBase::AddFromCleared() {
 if (current_size_ < allocated_size_) {
 return cast<TypeHandler>(elements_[current_size_++]);
 } else {
 return NULL;
 }
}

template <typename TypeHandler>
void RepeatedPtrFieldBase::AddAllocated(
 typename TypeHandler::Type* value) {
 // Make room for the new pointer.
 if (current_size_ == total_size_) {
 // The array is completely full with no cleared objects, so grow it.
 Reserve(total_size_ + 1);
 ++allocated_size_;
 } else if (allocated_size_ == total_size_) {
 // There is no more space in the pointer array because it contains some
 // cleared objects awaiting reuse. We don't want to grow the array in this
 // case because otherwise a loop calling AddAllocated() followed by Clear()
 // would leak memory.
 TypeHandler::Delete(cast<TypeHandler>(elements_[current_size_]));
 } else if (current_size_ < allocated_size_) {
 // We have some cleared objects. We don't care about their order, so we
 // can just move the first one to the end to make space.
 elements_[allocated_size_] = elements_[current_size_];
 ++allocated_size_;
 } else {
 // There are no cleared objects.
 ++allocated_size_;
 }

 elements_[current_size_++] = value;
}

template <typename TypeHandler>
inline typename TypeHandler::Type* RepeatedPtrFieldBase::ReleaseLast() {
 GOOGLE_DCHECK_GT(current_size_, 0);
 typename TypeHandler::Type* result =
 cast<TypeHandler>(elements_[--current_size_]);
 --allocated_size_;
 if (current_size_ < allocated_size_) {
 // There are cleared elements on the end; replace the removed element
 // with the last allocated element.
 elements_[current_size_] = elements_[allocated_size_];
 }
 return result;
}

inline int RepeatedPtrFieldBase::ClearedCount() const {
 return allocated_size_ - current_size_;
}

template <typename TypeHandler>
inline void RepeatedPtrFieldBase::AddCleared(
 typename TypeHandler::Type* value) {
 if (allocated_size_ == total_size_) Reserve(total_size_ + 1);
 elements_[allocated_size_++] = value;
}

template <typename TypeHandler>
inline typename TypeHandler::Type* RepeatedPtrFieldBase::ReleaseCleared() {
 GOOGLE_DCHECK_GT(allocated_size_, current_size_);
 return cast<TypeHandler>(elements_[--allocated_size_]);
}

} // namespace internal

// -------------------------------------------------------------------

template <typename Element>
class RepeatedPtrField<Element>::TypeHandler
 : public internal::GenericTypeHandler<Element> {
};

template <>
class RepeatedPtrField<string>::TypeHandler
 : public internal::StringTypeHandler {
};


template <typename Element>
inline RepeatedPtrField<Element>::RepeatedPtrField() {}

template <typename Element>
inline RepeatedPtrField<Element>::RepeatedPtrField(
 const RepeatedPtrField& other)
 : RepeatedPtrFieldBase() {
 CopyFrom(other);
}

template <typename Element>
template <typename Iter>
inline RepeatedPtrField<Element>::RepeatedPtrField(
 Iter begin, const Iter& end) {
 int reserve = internal::CalculateReserve(begin, end);
 if (reserve != -1) {
 Reserve(reserve);
 }
 for (; begin != end; ++begin) {
 *Add() = *begin;
 }
}

template <typename Element>
RepeatedPtrField<Element>::~RepeatedPtrField() {
 Destroy<TypeHandler>();
}

template <typename Element>
inline RepeatedPtrField<Element>& RepeatedPtrField<Element>::operator=(
 const RepeatedPtrField& other) {
 if (this != &other)
 CopyFrom(other);
 return *this;
}

template <typename Element>
inline bool RepeatedPtrField<Element>::empty() const {
 return RepeatedPtrFieldBase::empty();
}

template <typename Element>
inline int RepeatedPtrField<Element>::size() const {
 return RepeatedPtrFieldBase::size();
}

template <typename Element>
inline const Element& RepeatedPtrField<Element>::Get(int index) const {
 return RepeatedPtrFieldBase::Get<TypeHandler>(index);
}


template <typename Element>
inline Element* RepeatedPtrField<Element>::Mutable(int index) {
 return RepeatedPtrFieldBase::Mutable<TypeHandler>(index);
}

template <typename Element>
inline Element* RepeatedPtrField<Element>::Add() {
 return RepeatedPtrFieldBase::Add<TypeHandler>();
}

template <typename Element>
inline void RepeatedPtrField<Element>::RemoveLast() {
 RepeatedPtrFieldBase::RemoveLast<TypeHandler>();
}

template <typename Element>
inline void RepeatedPtrField<Element>::DeleteSubrange(int start, int num) {
 GOOGLE_DCHECK_GE(start, 0);
 GOOGLE_DCHECK_GE(num, 0);
 GOOGLE_DCHECK_LE(start + num, size());
 for (int i = 0; i < num; ++i)
 delete RepeatedPtrFieldBase::Mutable<TypeHandler>(start + i);
 ExtractSubrange(start, num, NULL);
}

template <typename Element>
inline void RepeatedPtrField<Element>::ExtractSubrange(
 int start, int num, Element** elements) {
 GOOGLE_DCHECK_GE(start, 0);
 GOOGLE_DCHECK_GE(num, 0);
 GOOGLE_DCHECK_LE(start + num, size());

 if (num > 0) {
 // Save the values of the removed elements if requested.
 if (elements != NULL) {
 for (int i = 0; i < num; ++i)
 elements[i] = RepeatedPtrFieldBase::Mutable<TypeHandler>(i + start);
 }
 CloseGap(start, num);
 }
}

template <typename Element>
inline void RepeatedPtrField<Element>::Clear() {
 RepeatedPtrFieldBase::Clear<TypeHandler>();
}

template <typename Element>
inline void RepeatedPtrField<Element>::MergeFrom(
 const RepeatedPtrField& other) {
 RepeatedPtrFieldBase::MergeFrom<TypeHandler>(other);
}

template <typename Element>
inline void RepeatedPtrField<Element>::CopyFrom(
 const RepeatedPtrField& other) {
 RepeatedPtrFieldBase::CopyFrom<TypeHandler>(other);
}

template <typename Element>
inline Element** RepeatedPtrField<Element>::mutable_data() {
 return RepeatedPtrFieldBase::mutable_data<TypeHandler>();
}

template <typename Element>
inline const Element* const* RepeatedPtrField<Element>::data() const {
 return RepeatedPtrFieldBase::data<TypeHandler>();
}

template <typename Element>
void RepeatedPtrField<Element>::Swap(RepeatedPtrField* other) {
 RepeatedPtrFieldBase::Swap(other);
}

template <typename Element>
void RepeatedPtrField<Element>::SwapElements(int index1, int index2) {
 RepeatedPtrFieldBase::SwapElements(index1, index2);
}

template <typename Element>
inline int RepeatedPtrField<Element>::SpaceUsedExcludingSelf() const {
 return RepeatedPtrFieldBase::SpaceUsedExcludingSelf<TypeHandler>();
}

template <typename Element>
inline void RepeatedPtrField<Element>::AddAllocated(Element* value) {
 RepeatedPtrFieldBase::AddAllocated<TypeHandler>(value);
}

template <typename Element>
inline Element* RepeatedPtrField<Element>::ReleaseLast() {
 return RepeatedPtrFieldBase::ReleaseLast<TypeHandler>();
}


template <typename Element>
inline int RepeatedPtrField<Element>::ClearedCount() const {
 return RepeatedPtrFieldBase::ClearedCount();
}

template <typename Element>
inline void RepeatedPtrField<Element>::AddCleared(Element* value) {
 return RepeatedPtrFieldBase::AddCleared<TypeHandler>(value);
}

template <typename Element>
inline Element* RepeatedPtrField<Element>::ReleaseCleared() {
 return RepeatedPtrFieldBase::ReleaseCleared<TypeHandler>();
}

template <typename Element>
inline void RepeatedPtrField<Element>::Reserve(int new_size) {
 return RepeatedPtrFieldBase::Reserve(new_size);
}

template <typename Element>
inline int RepeatedPtrField<Element>::Capacity() const {
 return RepeatedPtrFieldBase::Capacity();
}

// -------------------------------------------------------------------

namespace internal {

// STL-like iterator implementation for RepeatedPtrField. You should not
// refer to this class directly; use RepeatedPtrField<T>::iterator instead.
//
// The iterator for RepeatedPtrField<T>, RepeatedPtrIterator<T>, is
// very similar to iterator_ptr<T**> in util/gtl/iterator_adaptors.h,
// but adds random-access operators and is modified to wrap a void** base
// iterator (since RepeatedPtrField stores its array as a void* array and
// casting void** to T** would violate C++ aliasing rules).
//
// This code based on net/proto/proto-array-internal.h by Jeffrey Yasskin
// ([email protected]).
template<typename Element>
class RepeatedPtrIterator
 : public std::iterator<
 std::random_access_iterator_tag, Element> {
 public:
 typedef RepeatedPtrIterator<Element> iterator;
 typedef std::iterator<
 std::random_access_iterator_tag, Element> superclass;

 // Shadow the value_type in std::iterator<> because const_iterator::value_type
 // needs to be T, not const T.
 typedef typename remove_const<Element>::type value_type;

 // Let the compiler know that these are type names, so we don't have to
 // write "typename" in front of them everywhere.
 typedef typename superclass::reference reference;
 typedef typename superclass::pointer pointer;
 typedef typename superclass::difference_type difference_type;

 RepeatedPtrIterator() : it_(NULL) {}
 explicit RepeatedPtrIterator(void* const* it) : it_(it) {}

 // Allow "upcasting" from RepeatedPtrIterator<T**> to
 // RepeatedPtrIterator<const T*const*>.
 template<typename OtherElement>
 RepeatedPtrIterator(const RepeatedPtrIterator<OtherElement>& other)
 : it_(other.it_) {
 // Force a compiler error if the other type is not convertible to ours.
 if (false) {
 implicit_cast<Element*, OtherElement*>(0);
 }
 }

 // dereferenceable
 reference operator*() const { return *reinterpret_cast<Element*>(*it_); }
 pointer operator->() const { return &(operator*()); }

 // {inc,dec}rementable
 iterator& operator++() { ++it_; return *this; }
 iterator operator++(int) { return iterator(it_++); }
 iterator& operator--() { --it_; return *this; }
 iterator operator--(int) { return iterator(it_--); }

 // equality_comparable
 bool operator==(const iterator& x) const { return it_ == x.it_; }
 bool operator!=(const iterator& x) const { return it_ != x.it_; }

 // less_than_comparable
 bool operator<(const iterator& x) const { return it_ < x.it_; }
 bool operator<=(const iterator& x) const { return it_ <= x.it_; }
 bool operator>(const iterator& x) const { return it_ > x.it_; }
 bool operator>=(const iterator& x) const { return it_ >= x.it_; }

 // addable, subtractable
 iterator& operator+=(difference_type d) {
 it_ += d;
 return *this;
 }
 friend iterator operator+(iterator it, difference_type d) {
 it += d;
 return it;
 }
 friend iterator operator+(difference_type d, iterator it) {
 it += d;
 return it;
 }
 iterator& operator-=(difference_type d) {
 it_ -= d;
 return *this;
 }
 friend iterator operator-(iterator it, difference_type d) {
 it -= d;
 return it;
 }

 // indexable
 reference operator[](difference_type d) const { return *(*this + d); }

 // random access iterator
 difference_type operator-(const iterator& x) const { return it_ - x.it_; }

 private:
 template<typename OtherElement>
 friend class RepeatedPtrIterator;

 // The internal iterator.
 void* const* it_;
};

// Provide an iterator that operates on pointers to the underlying objects
// rather than the objects themselves as RepeatedPtrIterator does.
// Consider using this when working with stl algorithms that change
// the array.
// The VoidPtr template parameter holds the type-agnostic pointer value
// referenced by the iterator. It should either be "void *" for a mutable
// iterator, or "const void *" for a constant iterator.
template<typename Element, typename VoidPtr>
class RepeatedPtrOverPtrsIterator
 : public std::iterator<std::random_access_iterator_tag, Element*> {
 public:
 typedef RepeatedPtrOverPtrsIterator<Element, VoidPtr> iterator;
 typedef std::iterator<
 std::random_access_iterator_tag, Element*> superclass;

 // Shadow the value_type in std::iterator<> because const_iterator::value_type
 // needs to be T, not const T.
 typedef typename remove_const<Element*>::type value_type;

 // Let the compiler know that these are type names, so we don't have to
 // write "typename" in front of them everywhere.
 typedef typename superclass::reference reference;
 typedef typename superclass::pointer pointer;
 typedef typename superclass::difference_type difference_type;

 RepeatedPtrOverPtrsIterator() : it_(NULL) {}
 explicit RepeatedPtrOverPtrsIterator(VoidPtr* it) : it_(it) {}

 // dereferenceable
 reference operator*() const { return *reinterpret_cast<Element**>(it_); }
 pointer operator->() const { return &(operator*()); }

 // {inc,dec}rementable
 iterator& operator++() { ++it_; return *this; }
 iterator operator++(int) { return iterator(it_++); }
 iterator& operator--() { --it_; return *this; }
 iterator operator--(int) { return iterator(it_--); }

 // equality_comparable
 bool operator==(const iterator& x) const { return it_ == x.it_; }
 bool operator!=(const iterator& x) const { return it_ != x.it_; }

 // less_than_comparable
 bool operator<(const iterator& x) const { return it_ < x.it_; }
 bool operator<=(const iterator& x) const { return it_ <= x.it_; }
 bool operator>(const iterator& x) const { return it_ > x.it_; }
 bool operator>=(const iterator& x) const { return it_ >= x.it_; }

 // addable, subtractable
 iterator& operator+=(difference_type d) {
 it_ += d;
 return *this;
 }
 friend iterator operator+(iterator it, difference_type d) {
 it += d;
 return it;
 }
 friend iterator operator+(difference_type d, iterator it) {
 it += d;
 return it;
 }
 iterator& operator-=(difference_type d) {
 it_ -= d;
 return *this;
 }
 friend iterator operator-(iterator it, difference_type d) {
 it -= d;
 return it;
 }

 // indexable
 reference operator[](difference_type d) const { return *(*this + d); }

 // random access iterator
 difference_type operator-(const iterator& x) const { return it_ - x.it_; }

 private:
 template<typename OtherElement>
 friend class RepeatedPtrIterator;

 // The internal iterator.
 VoidPtr* it_;
};

} // namespace internal

template <typename Element>
inline typename RepeatedPtrField<Element>::iterator
RepeatedPtrField<Element>::begin() {
 return iterator(raw_data());
}
template <typename Element>
inline typename RepeatedPtrField<Element>::const_iterator
RepeatedPtrField<Element>::begin() const {
 return iterator(raw_data());
}
template <typename Element>
inline typename RepeatedPtrField<Element>::iterator
RepeatedPtrField<Element>::end() {
 return iterator(raw_data() + size());
}
template <typename Element>
inline typename RepeatedPtrField<Element>::const_iterator
RepeatedPtrField<Element>::end() const {
 return iterator(raw_data() + size());
}

template <typename Element>
inline typename RepeatedPtrField<Element>::pointer_iterator
RepeatedPtrField<Element>::pointer_begin() {
 return pointer_iterator(raw_mutable_data());
}
template <typename Element>
inline typename RepeatedPtrField<Element>::const_pointer_iterator
RepeatedPtrField<Element>::pointer_begin() const {
 return const_pointer_iterator(const_cast<const void**>(raw_mutable_data()));
}
template <typename Element>
inline typename RepeatedPtrField<Element>::pointer_iterator
RepeatedPtrField<Element>::pointer_end() {
 return pointer_iterator(raw_mutable_data() + size());
}
template <typename Element>
inline typename RepeatedPtrField<Element>::const_pointer_iterator
RepeatedPtrField<Element>::pointer_end() const {
 return const_pointer_iterator(
 const_cast<const void**>(raw_mutable_data() + size()));
}


// Iterators and helper functions that follow the spirit of the STL
// std::back_insert_iterator and std::back_inserter but are tailor-made
// for RepeatedField and RepatedPtrField. Typical usage would be:
//
// std::copy(some_sequence.begin(), some_sequence.end(),
// google::protobuf::RepeatedFieldBackInserter(proto.mutable_sequence()));
//
// Ported by johannes from util/gtl/proto-array-iterators.h

namespace internal {
// A back inserter for RepeatedField objects.
template<typename T> class RepeatedFieldBackInsertIterator
 : public std::iterator<std::output_iterator_tag, T> {
 public:
 explicit RepeatedFieldBackInsertIterator(
 RepeatedField<T>* const mutable_field)
 : field_(mutable_field) {
 }
 RepeatedFieldBackInsertIterator<T>& operator=(const T& value) {
 field_->Add(value);
 return *this;
 }
 RepeatedFieldBackInsertIterator<T>& operator*() {
 return *this;
 }
 RepeatedFieldBackInsertIterator<T>& operator++() {
 return *this;
 }
 RepeatedFieldBackInsertIterator<T>& operator++(int /* unused */) {
 return *this;
 }

 private:
 RepeatedField<T>* field_;
};

// A back inserter for RepeatedPtrField objects.
template<typename T> class RepeatedPtrFieldBackInsertIterator
 : public std::iterator<std::output_iterator_tag, T> {
 public:
 RepeatedPtrFieldBackInsertIterator(
 RepeatedPtrField<T>* const mutable_field)
 : field_(mutable_field) {
 }
 RepeatedPtrFieldBackInsertIterator<T>& operator=(const T& value) {
 *field_->Add() = value;
 return *this;
 }
 RepeatedPtrFieldBackInsertIterator<T>& operator=(
 const T* const ptr_to_value) {
 *field_->Add() = *ptr_to_value;
 return *this;
 }
 RepeatedPtrFieldBackInsertIterator<T>& operator*() {
 return *this;
 }
 RepeatedPtrFieldBackInsertIterator<T>& operator++() {
 return *this;
 }
 RepeatedPtrFieldBackInsertIterator<T>& operator++(int /* unused */) {
 return *this;
 }

 private:
 RepeatedPtrField<T>* field_;
};

// A back inserter for RepeatedPtrFields that inserts by transfering ownership
// of a pointer.
template<typename T> class AllocatedRepeatedPtrFieldBackInsertIterator
 : public std::iterator<std::output_iterator_tag, T> {
 public:
 explicit AllocatedRepeatedPtrFieldBackInsertIterator(
 RepeatedPtrField<T>* const mutable_field)
 : field_(mutable_field) {
 }
  AllocatedRepeatedPtrFieldBackInsertIterator<T>& operator=(
      T* const ptr_to_value) {
    field_->AddAllocated(ptr_to_value);
    return *this;
  }
  AllocatedRepeatedPtrFieldBackInsertIterator<T>& operator*() {
    return *this;
  }
  AllocatedRepeatedPtrFieldBackInsertIterator<T>& operator++() {
    return *this;
  }
  AllocatedRepeatedPtrFieldBackInsertIterator<T>& operator++(
      int /* unused */) {
    return *this;
  }

 private:
  RepeatedPtrField<T>* field_;
};
}  // namespace internal

// Provides a back insert iterator for RepeatedField instances,
// similar to std::back_inserter().
template<typename T> internal::RepeatedFieldBackInsertIterator<T>
RepeatedFieldBackInserter(RepeatedField<T>* const mutable_field) {
  return internal::RepeatedFieldBackInsertIterator<T>(mutable_field);
}

// Provides a back insert iterator for RepeatedPtrField instances,
// similar to std::back_inserter().
template<typename T> internal::RepeatedPtrFieldBackInsertIterator<T>
RepeatedPtrFieldBackInserter(RepeatedPtrField<T>* const mutable_field) {
  return internal::RepeatedPtrFieldBackInsertIterator<T>(mutable_field);
}

// Special back insert iterator for RepeatedPtrField instances, just in
// case someone wants to write generic template code that can access both
// RepeatedFields and RepeatedPtrFields using a common name.
template<typename T> internal::RepeatedPtrFieldBackInsertIterator<T>
RepeatedFieldBackInserter(RepeatedPtrField<T>* const mutable_field) {
  return internal::RepeatedPtrFieldBackInsertIterator<T>(mutable_field);
}

// Provides a back insert iterator for RepeatedPtrField instances
// similar to std::back_inserter() which transfers the ownership while
// copying elements.
template<typename T> internal::AllocatedRepeatedPtrFieldBackInsertIterator<T>
AllocatedRepeatedPtrFieldBackInserter(
    RepeatedPtrField<T>* const mutable_field) {
  return internal::AllocatedRepeatedPtrFieldBackInsertIterator<T>(
      mutable_field);
}

}  // namespace protobuf

}  // namespace google
#endif  // GOOGLE_PROTOBUF_REPEATED_FIELD_H__