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filewritestream.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_FILEWRITESTREAM_H_
16#define RAPIDJSON_FILEWRITESTREAM_H_
17
18#include "stream.h"
19#include <cstdio>
20
21#ifdef __clang__
22RAPIDJSON_DIAG_PUSH
23RAPIDJSON_DIAG_OFF(unreachable-code)
24#endif
25
26RAPIDJSON_NAMESPACE_BEGIN
27
28//! Wrapper of C file stream for input using fread().
29/*!
30 \note implements Stream concept
31*/
32 class FileWriteStream {
33 public:
34 typedef char Ch; //!< Character type. Only support char.
35
36 FileWriteStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferEnd_(buffer + bufferSize), current_(buffer_) {
37 RAPIDJSON_ASSERT(fp_ != 0);
38 }
39
40 void Put(char c) {
41 if (current_ >= bufferEnd_)
42 Flush();
43
44 *current_++ = c;
45 }
46
47 void PutN(char c, size_t n) {
48 size_t avail = static_cast<size_t>(bufferEnd_ - current_);
49 while (n > avail) {
50 std::memset(current_, c, avail);
51 current_ += avail;
52 Flush();
53 n -= avail;
54 avail = static_cast<size_t>(bufferEnd_ - current_);
55 }
56
57 if (n > 0) {
58 std::memset(current_, c, n);
59 current_ += n;
60 }
61 }
62
63 void Flush() {
64 if (current_ != buffer_) {
65 size_t result = fwrite(buffer_, 1, static_cast<size_t>(current_ - buffer_), fp_);
66 if (result < static_cast<size_t>(current_ - buffer_)) {
67 // failure deliberately ignored at this time
68 // added to avoid warn_unused_result build errors
69 }
70 current_ = buffer_;
71 }
72 }
73
74 // Not implemented
75 char Peek() const { RAPIDJSON_ASSERT(false); return 0; }
76 char Take() { RAPIDJSON_ASSERT(false); return 0; }
77 size_t Tell() const { RAPIDJSON_ASSERT(false); return 0; }
78 char* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
79 size_t PutEnd(char*) { RAPIDJSON_ASSERT(false); return 0; }
80
81 private:
82 // Prohibit copy constructor & assignment operator.
83 FileWriteStream(const FileWriteStream&);
84 FileWriteStream& operator=(const FileWriteStream&);
85
86 std::FILE* fp_;
87 char *buffer_;
88 char *bufferEnd_;
89 char *current_;
90};
91
92//! Implement specialized version of PutN() with memset() for better performance.
93 template<>
94 inline void PutN(FileWriteStream& stream, char c, size_t n) {
95 stream.PutN(c, n);
96}
97
98RAPIDJSON_NAMESPACE_END
99
100#ifdef __clang__
101RAPIDJSON_DIAG_POP
102#endif
103
104#endif // RAPIDJSON_FILESTREAM_H_
rapidjson::FileWriteStream
Wrapper of C file stream for input using fread().
定义 filewritestream.h:32
rapidjson::FileWriteStream::Ch
char Ch
Character type. Only support char.
定义 filewritestream.h:34
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
定义 rapidjson.h:402
rapidjson::PutN
void PutN(FileWriteStream &stream, char c, size_t n)
Implement specialized version of PutN() with memset() for better performance.
定义 filewritestream.h:94