ceph/src/rapidjson/include/rapidjson/memorystream.h

   1 // Tencent is pleased to support the open source community by making RapidJSON available.
   2 //
   3 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
   4 //
   5 // Licensed under the MIT License (the "License"); you may not use this file except
   6 // in compliance with the License. You may obtain a copy of the License at
   7 //
   8 // http://opensource.org/licenses/MIT
   9 //
  10 // Unless required by applicable law or agreed to in writing, software distributed
  11 // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
  12 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
  13 // specific language governing permissions and limitations under the License.
  14
  15 #ifndef RAPIDJSON_MEMORYSTREAM_H_
  16 #define RAPIDJSON_MEMORYSTREAM_H_
  17
  18 #include "stream.h"
  19
  20 #ifdef __clang__
  21 RAPIDJSON_DIAG_PUSH
  22 RAPIDJSON_DIAG_OFF(unreachable-code)
  23 RAPIDJSON_DIAG_OFF(missing-noreturn)
  24 #endif
  25
  26 RAPIDJSON_NAMESPACE_BEGIN
  27
  28 //! Represents an in-memory input byte stream.
  29 /*!
  30     This class is mainly for being wrapped by EncodedInputStream or AutoUTFInputStream.
  31
  32     It is similar to FileReadBuffer but the source is an in-memory buffer instead of a file.
  33
  34     Differences between MemoryStream and StringStream:
  35     1. StringStream has encoding but MemoryStream is a byte stream.
  36     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.
  37     3. MemoryStream supports Peek4() for encoding detection. StringStream is specified with an encoding so it should not have Peek4().
  38     \note implements Stream concept
  39 */
  40 struct MemoryStream {
  41     typedef char Ch; // byte
  42
  43     MemoryStream(const Ch *src, size_t size) : src_(src), begin_(src), end_(src + size), size_(size) {}
  44
  45     Ch Peek() const { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_; }
  46     Ch Take() { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_++; }
  47     size_t Tell() const { return static_cast<size_t>(src_ - begin_); }
  48
  49     Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
  50     void Put(Ch) { RAPIDJSON_ASSERT(false); }
  51     void Flush() { RAPIDJSON_ASSERT(false); }
  52     size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
  53
  54     // For encoding detection only.
  55     const Ch* Peek4() const {
  56         return Tell() + 4 <= size_ ? src_ : 0;
  57     }
  58
  59     const Ch* src_;     //!< Current read position.
  60     const Ch* begin_;   //!< Original head of the string.
  61     const Ch* end_;     //!< End of stream.
  62     size_t size_;       //!< Size of the stream.
  63 };
  64
  65 RAPIDJSON_NAMESPACE_END
  66
  67 #ifdef __clang__
  68 RAPIDJSON_DIAG_POP
  69 #endif
  70
  71 #endif // RAPIDJSON_MEMORYBUFFER_H_