filewritestream.h

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// 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_FILEWRITESTREAM_H_
#define RAPIDJSON_FILEWRITESTREAM_H_

#include "stream.h"
#include <cstdio>

#if __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(unreachable - code)
#endif

RAPIDJSON_NAMESPACE_BEGIN


class FileWriteStream
{
public:
  typedef char Ch;  

  FileWriteStream(std::FILE* fp, char* buffer, size_t bufferSize)
    : fp_(fp), buffer_(buffer), bufferEnd_(buffer + bufferSize), current_(buffer_)
  {
    RAPIDJSON_ASSERT(fp_ != 0);
  }

  void Put(char c)
  {
    if (current_ >= bufferEnd_)
      Flush();

    *current_++ = c;
  }

  void PutN(char c, size_t n)
  {
    size_t avail = static_cast<size_t>(bufferEnd_ - current_);
    while (n > avail)
    {
      std::memset(current_, c, avail);
      current_ += avail;
      Flush();
      n -= avail;
      avail = static_cast<size_t>(bufferEnd_ - current_);
    }

    if (n > 0)
    {
      std::memset(current_, c, n);
      current_ += n;
    }
  }

  void Flush()
  {
    if (current_ != buffer_)
    {
      size_t result = std::fwrite(buffer_, 1, static_cast<size_t>(current_ - buffer_), fp_);
      if (result < static_cast<size_t>(current_ - buffer_))
      {
        // failure deliberately ignored at this time
        // added to avoid warn_unused_result build errors
      }
      current_ = buffer_;
    }
  }

  // Not implemented
  char Peek() const
  {
    RAPIDJSON_ASSERT(false);
    return 0;
  }
  char Take()
  {
    RAPIDJSON_ASSERT(false);
    return 0;
  }
  size_t Tell() const
  {
    RAPIDJSON_ASSERT(false);
    return 0;
  }
  char* PutBegin()
  {
    RAPIDJSON_ASSERT(false);
    return 0;
  }
  size_t PutEnd(char*)
  {
    RAPIDJSON_ASSERT(false);
    return 0;
  }

private:
  // Prohibit copy constructor & assignment operator.
  FileWriteStream(const FileWriteStream&);
  FileWriteStream& operator=(const FileWriteStream&);

  std::FILE* fp_;
  char* buffer_;
  char* bufferEnd_;
  char* current_;
};

template <>
inline void PutN(FileWriteStream& stream, char c, size_t n)
{
  stream.PutN(c, n);
}

RAPIDJSON_NAMESPACE_END

#if __clang__
RAPIDJSON_DIAG_POP
#endif

#endif  // RAPIDJSON_FILESTREAM_H_