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_MEMORYBUFFER_H_
16#define RAPIDJSON_MEMORYBUFFER_H_
17
18#include "stream.h"
19#include "internal/stack.h"
20
21RAPIDJSON_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*/
36template <typename Allocator = CrtAllocator>
37struct 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
60typedef GenericMemoryBuffer<> MemoryBuffer;
61
62//! Implement specialized version of PutN() with memset() for better performance.
63template<>
64inline void PutN(MemoryBuffer& memoryBuffer, char c, size_t n) {
65    std::memset(memoryBuffer.stack_.Push<char>(n), c, n * sizeof(c));
66}
67
68RAPIDJSON_NAMESPACE_END
69
70#endif // RAPIDJSON_MEMORYBUFFER_H_