RapidJSON: include/rapidjson/filereadstream.h Source File

filereadstream.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_FILEREADSTREAM_H_
16 #define RAPIDJSON_FILEREADSTREAM_H_
17
18 #include "stream.h"
19 #include <cstdio>
20
21 #ifdef __clang__
22 RAPIDJSON_DIAG_PUSH
23 RAPIDJSON_DIAG_OFF(padded)
24 RAPIDJSON_DIAG_OFF(unreachable-code)
25 RAPIDJSON_DIAG_OFF(missing-noreturn)
26 #endif
27
28 RAPIDJSON_NAMESPACE_BEGIN
29
30 //! File byte stream for input using fread().
31 /*!
32 \note implements Stream concept
33 */
34 class FileReadStream {
35 public:
36 typedef char Ch; //!< Character type (byte).
37
38 //! Constructor.
39 /*!
40 \param fp File pointer opened for read.
41 \param buffer user-supplied buffer.
42 \param bufferSize size of buffer in bytes. Must >=4 bytes.
43 */
44 FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
45 RAPIDJSON_ASSERT(fp_ != 0);
46 RAPIDJSON_ASSERT(bufferSize >= 4);
47 Read();
48 }
49
50 Ch Peek() const { return *current_; }
51 Ch Take() { Ch c = *current_; Read(); return c; }
52 size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
53
54 // Not implemented
55 void Put(Ch) { RAPIDJSON_ASSERT(false); }
56 void Flush() { RAPIDJSON_ASSERT(false); }
57 Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
58 size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
59
60 // For encoding detection only.
61 const Ch* Peek4() const {
62 return (current_ + 4 - !eof_ <= bufferLast_) ? current_ : 0;
63 }
64
65 private:
66 void Read() {
67 if (current_ < bufferLast_)
68 ++current_;
69 else if (!eof_) {
70 count_ += readCount_;
71 readCount_ = std::fread(buffer_, 1, bufferSize_, fp_);
72 bufferLast_ = buffer_ + readCount_ - 1;
73 current_ = buffer_;
74
75 if (readCount_ < bufferSize_) {
76 buffer_[readCount_] = '\0';
77 ++bufferLast_;
78 eof_ = true;
79 }
80 }
81 }
82
83 std::FILE* fp_;
84 Ch *buffer_;
85 size_t bufferSize_;
86 Ch *bufferLast_;
87 Ch *current_;
88 size_t readCount_;
89 size_t count_; //!< Number of characters read
90 bool eof_;
91 };
92
93 RAPIDJSON_NAMESPACE_END
94
95 #ifdef __clang__
96 RAPIDJSON_DIAG_POP
97 #endif
98
99 #endif // RAPIDJSON_FILESTREAM_H_
rapidjson::FileReadStream::Ch
char Ch
Character type (byte).
Definition: filereadstream.h:36
rapidjson::FileReadStream::FileReadStream
FileReadStream(std::FILE *fp, char *buffer, size_t bufferSize)
Constructor.
Definition: filereadstream.h:44
rapidjson::FileReadStream
File byte stream for input using fread().
Definition: filereadstream.h:34
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406