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_FILEREADSTREAM_H_
  #define RAPIDJSON_FILEREADSTREAM_H_
  
  #include "rapidjson.h"
  #include <cstdio>
  
  
  RAPIDJSON_NAMESPACE_BEGIN
  
  //! File byte stream for input using fread().
  /*!
      \note implements Stream concept
  */
  class FileReadStream {
   public:
    typedef char Ch;    //!< Character type (byte).
  
    //! Constructor.
    /*!
        \param fp File pointer opened for read.
        \param buffer user-supplied buffer.
        \param bufferSize size of buffer in bytes. Must >=4 bytes.
    */
    FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
      RAPIDJSON_ASSERT(fp_ != 0);
      RAPIDJSON_ASSERT(bufferSize >= 4);
      Read();
    }
  
    Ch Peek() const { return *current_; }
    Ch Take() {
      Ch c = *current_;
      Read();
      return c;
    }
    size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
  
    // Not implemented
    void Put(Ch) { RAPIDJSON_ASSERT(false); }
    void Flush() { RAPIDJSON_ASSERT(false); }
    Ch* PutBegin() {
      RAPIDJSON_ASSERT(false);
      return 0;
    }
    size_t PutEnd(Ch*) {
      RAPIDJSON_ASSERT(false);
      return 0;
    }
  
    // For encoding detection only.
    const Ch* Peek4() const {
      return (current_ + 4 <= bufferLast_) ? current_ : 0;
    }
  
   private:
    void Read() {
      if (current_ < bufferLast_)
        ++current_;
      else if (!eof_) {
        count_ += readCount_;
        readCount_ = fread(buffer_, 1, bufferSize_, fp_);
        bufferLast_ = buffer_ + readCount_ - 1;
        current_ = buffer_;
  
        if (readCount_ < bufferSize_) {
          buffer_[readCount_] = '\0';
          ++bufferLast_;
          eof_ = true;
        }
      }
    }
  
    std::FILE* fp_;
    Ch* buffer_;
    size_t bufferSize_;
    Ch* bufferLast_;
    Ch* current_;
    size_t readCount_;
    size_t count_;  //!< Number of characters read
    bool eof_;
  };
  
  RAPIDJSON_NAMESPACE_END
  
  #endif // RAPIDJSON_FILESTREAM_H_
  