text: // Tencent is pleased to support the open source community by making RapidJSON
  // available.
  //
  // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All
  // rights reserved.
  //
  // Licensed under the MIT License (the "License"); you may not use this file
  // except in compliance with the License. You may obtain a copy of the License
  // at
  //
  // http://opensource.org/licenses/MIT
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  // License for the specific language governing permissions and limitations under
  // the License.
  
  #ifndef RAPIDJSON_MEMORYBUFFER_H_
  #define RAPIDJSON_MEMORYBUFFER_H_
  
  #include "internal/stack.h"
  #include "stream.h"
  
  RAPIDJSON_NAMESPACE_BEGIN
  
  //! Represents an in-memory output byte stream.
  /*!
      This class is mainly for being wrapped by EncodedOutputStream or
     AutoUTFOutputStream.
  
      It is similar to FileWriteBuffer but the destination is an in-memory buffer
     instead of a file.
  
      Differences between MemoryBuffer and StringBuffer:
      1. StringBuffer has Encoding but MemoryBuffer is only a byte buffer.
      2. StringBuffer::GetString() returns a null-terminated string.
     MemoryBuffer::GetBuffer() returns a buffer without terminator.
  
      \tparam Allocator type for allocating memory buffer.
      \note implements Stream concept
  */
  template <typename Allocator = CrtAllocator>
  struct GenericMemoryBuffer {
    typedef char Ch;  // byte
  
    GenericMemoryBuffer(Allocator *allocator = 0,
                        size_t capacity = kDefaultCapacity)
        : stack_(allocator, capacity) {}
  
    void Put(Ch c) { *stack_.template Push<Ch>() = c; }
    void Flush() {}
  
    void Clear() { stack_.Clear(); }
    void ShrinkToFit() { stack_.ShrinkToFit(); }
    Ch *Push(size_t count) { return stack_.template Push<Ch>(count); }
    void Pop(size_t count) { stack_.template Pop<Ch>(count); }
  
    const Ch *GetBuffer() const { return stack_.template Bottom<Ch>(); }
  
    size_t GetSize() const { return stack_.GetSize(); }
  
    static const size_t kDefaultCapacity = 256;
    mutable internal::Stack<Allocator> stack_;
  };
  
  typedef GenericMemoryBuffer<> MemoryBuffer;
  
  //! Implement specialized version of PutN() with memset() for better
  //! performance.
  template <>
  inline void PutN(MemoryBuffer &memoryBuffer, char c, size_t n) {
    std::memset(memoryBuffer.stack_.Push<char>(n), c, n * sizeof(c));
  }
  
  RAPIDJSON_NAMESPACE_END
  
  #endif  // RAPIDJSON_MEMORYBUFFER_H_
  