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 "rapidjson.h"
19
20RAPIDJSON_NAMESPACE_BEGIN
21
22//! Represents an in-memory input byte stream.
23/*!
24    This class is mainly for being wrapped by EncodedInputStream or AutoUTFInputStream.
25
26    It is similar to FileReadBuffer but the source is an in-memory buffer instead of a file.
27
28    Differences between MemoryStream and StringStream:
29    1. StringStream has encoding but MemoryStream is a byte stream.
30    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.
31    3. MemoryStream supports Peek4() for encoding detection. StringStream is specified with an encoding so it should not have Peek4().
32    \note implements Stream concept
33*/
34struct MemoryStream {
35    typedef char Ch; // byte
36
37    MemoryStream(const Ch *src, size_t size) : src_(src), begin_(src), end_(src + size), size_(size) {}
38
39    Ch Peek() const { return (src_ == end_) ? '\0' : *src_; }
40    Ch Take() { return (src_ == end_) ? '\0' : *src_++; }
41    size_t Tell() const { return static_cast<size_t>(src_ - begin_); }
42
43    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
44    void Put(Ch) { RAPIDJSON_ASSERT(false); }
45    void Flush() { RAPIDJSON_ASSERT(false); }
46    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
47
48    // For encoding detection only.
49    const Ch* Peek4() const {
50        return Tell() + 4 <= size_ ? src_ : 0;
51    }
52
53    const Ch* src_;     //!< Current read position.
54    const Ch* begin_;   //!< Original head of the string.
55    const Ch* end_;     //!< End of stream.
56    size_t size_;       //!< Size of the stream.
57};
58
59RAPIDJSON_NAMESPACE_END
60
61#endif // RAPIDJSON_MEMORYBUFFER_H_
62