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. 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_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 */
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 <= 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_
FileReadStream(std::FILE *fp, char *buffer, size_t bufferSize)
Constructor.
Definition: filereadstream.h:44
File byte stream for input using fread().
Definition: filereadstream.h:34
char Ch
Character type (byte).
Definition: filereadstream.h:36
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:411