memorystream.h

Engine/source/persistence/rapidjson/memorystream.h

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Detailed Description

 1
 2// Tencent is pleased to support the open source community by making RapidJSON available.
 3// 
 4// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
 5//
 6// Licensed under the MIT License (the "License"); you may not use this file except
 7// in compliance with the License. You may obtain a copy of the License at
 8//
 9// http://opensource.org/licenses/MIT
10//
11// Unless required by applicable law or agreed to in writing, software distributed 
12// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
13// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
14// specific language governing permissions and limitations under the License.
15
16#ifndef RAPIDJSON_MEMORYSTREAM_H_
17#define RAPIDJSON_MEMORYSTREAM_H_
18
19#include "stream.h"
20
21#ifdef __clang__
22RAPIDJSON_DIAG_PUSH
23RAPIDJSON_DIAG_OFF(unreachable-code)
24RAPIDJSON_DIAG_OFF(missing-noreturn)
25#endif
26
27RAPIDJSON_NAMESPACE_BEGIN
28
29//! Represents an in-memory input byte stream.
30/*!
31    This class is mainly for being wrapped by EncodedInputStream or AutoUTFInputStream.
32
33    It is similar to FileReadBuffer but the source is an in-memory buffer instead of a file.
34
35    Differences between MemoryStream and StringStream:
36    1. StringStream has encoding but MemoryStream is a byte stream.
37    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.
38    3. MemoryStream supports Peek4() for encoding detection. StringStream is specified with an encoding so it should not have Peek4().
39    \note implements Stream concept
40*/
41struct MemoryStream {
42    typedef char Ch; // byte
43
44    MemoryStream(const Ch *src, size_t size) : src_(src), begin_(src), end_(src + size), size_(size) {}
45
46    Ch Peek() const { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_; }
47    Ch Take() { return RAPIDJSON_UNLIKELY(src_ == end_) ? '\0' : *src_++; }
48    size_t Tell() const { return static_cast<size_t>(src_ - begin_); }
49
50    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
51    void Put(Ch) { RAPIDJSON_ASSERT(false); }
52    void Flush() { RAPIDJSON_ASSERT(false); }
53    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
54
55    // For encoding detection only.
56    const Ch* Peek4() const {
57        return Tell() + 4 <= size_ ? src_ : 0;
58    }
59
60    const Ch* src_;     //!< Current read position.
61    const Ch* begin_;   //!< Original head of the string.
62    const Ch* end_;     //!< End of stream.
63    size_t size_;       //!< Size of the stream.
64};
65
66RAPIDJSON_NAMESPACE_END
67
68#ifdef __clang__
69RAPIDJSON_DIAG_POP
70#endif
71
72#endif // RAPIDJSON_MEMORYBUFFER_H_
73