RapidJSON: include/rapidjson/filewritestream.h Source File

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.
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__
22 RAPIDJSON_DIAG_PUSH
23 RAPIDJSON_DIAG_OFF(unreachable-code)
24 #endif
25
26 RAPIDJSON_NAMESPACE_BEGIN
27
28 //! Wrapper of C file stream for output using fwrite().
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 = std::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
98 RAPIDJSON_NAMESPACE_END
99
100 #ifdef __clang__
101 RAPIDJSON_DIAG_POP
102 #endif
103
104 #endif // RAPIDJSON_FILESTREAM_H_
rapidjson::FileWriteStream
Wrapper of C file stream for output using fwrite().
Definition: filewritestream.h:32
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406
rapidjson::FileWriteStream::Ch
char Ch
Character type. Only support char.
Definition: filewritestream.h:34
rapidjson::PutN
void PutN(FileWriteStream &stream, char c, size_t n)
Implement specialized version of PutN() with memset() for better performance.
Definition: filewritestream.h:94