lio-cpp/livox/common/rapidjson/memorybuffer.h

// 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_