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_MEMORYSTREAM_H_
  #define RAPIDJSON_MEMORYSTREAM_H_
  
  #include "stream.h"
  
  #ifdef __clang__
  RAPIDJSON_DIAG_PUSH
  RAPIDJSON_DIAG_OFF(unreachable-code)
  RAPIDJSON_DIAG_OFF(missing-noreturn)
  #endif
  
  RAPIDJSON_NAMESPACE_BEGIN
  
  //! Represents an in-memory input byte stream.
  /*!
      This class is mainly for being wrapped by EncodedInputStream or AutoUTFInputStream.
  
      It is similar to FileReadBuffer but the source is an in-memory buffer instead of a file.
  
      Differences between MemoryStream and StringStream:
      1. StringStream has encoding but MemoryStream is a byte stream.
      2. MemoryStream needs size of the source buffer and the buffer don't need to be null terminated. StringStream assume null-terminated string as source.
      3. MemoryStream supports Peek4() for encoding detection. StringStream is specified with an encoding so it should not have Peek4().
      \note implements Stream concept
  */
  struct MemoryStream {
      typedef char Ch; // byte
  
      MemoryStream(const Ch *src, size_t size) : src_(src), begin_(src), end_(src + size), size_(size) {}
  
      Ch Peek() const { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_; }
      Ch Take() { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_++; }
      size_t Tell() const { return static_cast<size_t>(src_ - begin_); }
  
      Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
      void Put(Ch) { RAPIDJSON_ASSERT(false); }
      void Flush() { RAPIDJSON_ASSERT(false); }
      size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
  
      // For encoding detection only.
      const Ch* Peek4() const {
          return Tell() + 4 <= size_ ? src_ : 0;
      }
  
      const Ch* src_;     //!< Current read position.
      const Ch* begin_;   //!< Original head of the string.
      const Ch* end_;     //!< End of stream.
      size_t size_;       //!< Size of the stream.
  };
  
  RAPIDJSON_NAMESPACE_END
  
  #ifdef __clang__
  RAPIDJSON_DIAG_POP
  #endif
  
  #endif // RAPIDJSON_MEMORYBUFFER_H_
  