ceph/src/s3select/rapidjson/include/rapidjson/memorybuffer.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.
   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_MEMORYBUFFER_H_
  16 #define RAPIDJSON_MEMORYBUFFER_H_
  17
  18 #include "stream.h"
  19 #include "internal/stack.h"
  20
  21 RAPIDJSON_NAMESPACE_BEGIN
  22
  23 //! Represents an in-memory output byte stream.
  24 /*!
  25     This class is mainly for being wrapped by EncodedOutputStream or AutoUTFOutputStream.
  26
  27     It is similar to FileWriteBuffer but the destination is an in-memory buffer instead of a file.
  28
  29     Differences between MemoryBuffer and StringBuffer:
  30     1. StringBuffer has Encoding but MemoryBuffer is only a byte buffer.
  31     2. StringBuffer::GetString() returns a null-terminated string. MemoryBuffer::GetBuffer() returns a buffer without terminator.
  32
  33     \tparam Allocator type for allocating memory buffer.
  34     \note implements Stream concept
  35 */
  36 template <typename Allocator = CrtAllocator>
  37 struct GenericMemoryBuffer {
  38     typedef char Ch; // byte
  39
  40     GenericMemoryBuffer(Allocator* allocator = 0, size_t capacity = kDefaultCapacity) : stack_(allocator, capacity) {}
  41
  42     void Put(Ch c) { *stack_.template Push<Ch>() = c; }
  43     void Flush() {}
  44
  45     void Clear() { stack_.Clear(); }
  46     void ShrinkToFit() { stack_.ShrinkToFit(); }
  47     Ch* Push(size_t count) { return stack_.template Push<Ch>(count); }
  48     void Pop(size_t count) { stack_.template Pop<Ch>(count); }
  49
  50     const Ch* GetBuffer() const {
  51         return stack_.template Bottom<Ch>();
  52     }
  53
  54     size_t GetSize() const { return stack_.GetSize(); }
  55
  56     static const size_t kDefaultCapacity = 256;
  57     mutable internal::Stack<Allocator> stack_;
  58 };
  59
  60 typedef GenericMemoryBuffer<> MemoryBuffer;
  61
  62 //! Implement specialized version of PutN() with memset() for better performance.
  63 template<>
  64 inline void PutN(MemoryBuffer& memoryBuffer, char c, size_t n) {
  65     std::memset(memoryBuffer.stack_.Push<char>(n), c, n * sizeof(c));
  66 }
  67
  68 RAPIDJSON_NAMESPACE_END
  69
  70 #endif // RAPIDJSON_MEMORYBUFFER_H_