RapidJSON: include/rapidjson/istreamwrapper.h Source File

istreamwrapper.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_ISTREAMWRAPPER_H_
16 #define RAPIDJSON_ISTREAMWRAPPER_H_
17
18 #include "stream.h"
19 #include <iosfwd>
20 #include <ios>
21
22 #ifdef __clang__
23 RAPIDJSON_DIAG_PUSH
24 RAPIDJSON_DIAG_OFF(padded)
25 #elif defined(_MSC_VER)
26 RAPIDJSON_DIAG_PUSH
27 RAPIDJSON_DIAG_OFF(4351) // new behavior: elements of array 'array' will be default initialized
28 #endif
29
30 RAPIDJSON_NAMESPACE_BEGIN
31
32 //! Wrapper of \c std::basic_istream into RapidJSON's Stream concept.
33 /*!
34 The classes can be wrapped including but not limited to:
35
36 - \c std::istringstream
37 - \c std::stringstream
38 - \c std::wistringstream
39 - \c std::wstringstream
40 - \c std::ifstream
41 - \c std::fstream
42 - \c std::wifstream
43 - \c std::wfstream
44
45 \tparam StreamType Class derived from \c std::basic_istream.
46 */
47
48 template <typename StreamType>
49 class BasicIStreamWrapper {
50 public:
51 typedef typename StreamType::char_type Ch;
52
53 //! Constructor.
54 /*!
55 \param stream stream opened for read.
56 */
57 BasicIStreamWrapper(StreamType &stream) : stream_(stream), buffer_(peekBuffer_), bufferSize_(4), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
58 Read();
59 }
60
61 //! Constructor.
62 /*!
63 \param stream stream opened for read.
64 \param buffer user-supplied buffer.
65 \param bufferSize size of buffer in bytes. Must >=4 bytes.
66 */
67 BasicIStreamWrapper(StreamType &stream, char* buffer, size_t bufferSize) : stream_(stream), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) {
68 RAPIDJSON_ASSERT(bufferSize >= 4);
69 Read();
70 }
71
72 Ch Peek() const { return *current_; }
73 Ch Take() { Ch c = *current_; Read(); return c; }
74 size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }
75
76 // Not implemented
77 void Put(Ch) { RAPIDJSON_ASSERT(false); }
78 void Flush() { RAPIDJSON_ASSERT(false); }
79 Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
80 size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
81
82 // For encoding detection only.
83 const Ch* Peek4() const {
84 return (current_ + 4 - !eof_ <= bufferLast_) ? current_ : 0;
85 }
86
87 private:
88 BasicIStreamWrapper();
89 BasicIStreamWrapper(const BasicIStreamWrapper&);
90 BasicIStreamWrapper& operator=(const BasicIStreamWrapper&);
91
92 void Read() {
93 if (current_ < bufferLast_)
94 ++current_;
95 else if (!eof_) {
96 count_ += readCount_;
97 readCount_ = bufferSize_;
98 bufferLast_ = buffer_ + readCount_ - 1;
99 current_ = buffer_;
100
101 if (!stream_.read(buffer_, static_cast<std::streamsize>(bufferSize_))) {
102 readCount_ = static_cast<size_t>(stream_.gcount());
103 *(bufferLast_ = buffer_ + readCount_) = '\0';
104 eof_ = true;
105 }
106 }
107 }
108
109 StreamType &stream_;
110 Ch peekBuffer_[4], *buffer_;
111 size_t bufferSize_;
112 Ch *bufferLast_;
113 Ch *current_;
114 size_t readCount_;
115 size_t count_; //!< Number of characters read
116 bool eof_;
117 };
118
119 typedef BasicIStreamWrapper<std::istream> IStreamWrapper;
120 typedef BasicIStreamWrapper<std::wistream> WIStreamWrapper;
121
122 #if defined(__clang__) || defined(_MSC_VER)
123 RAPIDJSON_DIAG_POP
124 #endif
125
126 RAPIDJSON_NAMESPACE_END
127
128 #endif // RAPIDJSON_ISTREAMWRAPPER_H_
rapidjson::BasicIStreamWrapper
Wrapper of std::basic_istream into RapidJSON's Stream concept.
Definition: istreamwrapper.h:49
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406
rapidjson::BasicIStreamWrapper::BasicIStreamWrapper
BasicIStreamWrapper(StreamType &stream)
Constructor.
Definition: istreamwrapper.h:57
rapidjson::BasicIStreamWrapper::BasicIStreamWrapper
BasicIStreamWrapper(StreamType &stream, char *buffer, size_t bufferSize)
Constructor.
Definition: istreamwrapper.h:67