RapidJSON: include/rapidjson/stream.h Source File

stream.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 #include "rapidjson.h"
16
17 #ifndef RAPIDJSON_STREAM_H_
18 #define RAPIDJSON_STREAM_H_
19
20 #include "encodings.h"
21
22 RAPIDJSON_NAMESPACE_BEGIN
23
24 ///////////////////////////////////////////////////////////////////////////////
25 // Stream
26
27 /*! \class rapidjson::Stream
28 \brief Concept for reading and writing characters.
29
30 For read-only stream, no need to implement PutBegin(), Put(), Flush() and PutEnd().
31
32 For write-only stream, only need to implement Put() and Flush().
33
34 \code
35 concept Stream {
36 typename Ch; //!< Character type of the stream.
37
38 //! Read the current character from stream without moving the read cursor.
39 Ch Peek() const;
40
41 //! Read the current character from stream and moving the read cursor to next character.
42 Ch Take();
43
44 //! Get the current read cursor.
45 //! \return Number of characters read from start.
46 size_t Tell();
47
48 //! Begin writing operation at the current read pointer.
49 //! \return The begin writer pointer.
50 Ch* PutBegin();
51
52 //! Write a character.
53 void Put(Ch c);
54
55 //! Flush the buffer.
56 void Flush();
57
58 //! End the writing operation.
59 //! \param begin The begin write pointer returned by PutBegin().
60 //! \return Number of characters written.
61 size_t PutEnd(Ch* begin);
62 }
63 \endcode
64 */
65
66 //! Provides additional information for stream.
67 /*!
68 By using traits pattern, this type provides a default configuration for stream.
69 For custom stream, this type can be specialized for other configuration.
70 See TEST(Reader, CustomStringStream) in readertest.cpp for example.
71 */
72 template<typename Stream>
73 struct StreamTraits {
74 //! Whether to make local copy of stream for optimization during parsing.
75 /*!
76 By default, for safety, streams do not use local copy optimization.
77 Stream that can be copied fast should specialize this, like StreamTraits<StringStream>.
78 */
79 enum { copyOptimization = 0 };
80 };
81
82 //! Reserve n characters for writing to a stream.
83 template<typename Stream>
84 inline void PutReserve(Stream& stream, size_t count) {
85 (void)stream;
86 (void)count;
87 }
88
89 //! Write character to a stream, presuming buffer is reserved.
90 template<typename Stream>
91 inline void PutUnsafe(Stream& stream, typename Stream::Ch c) {
92 stream.Put(c);
93 }
94
95 //! Put N copies of a character to a stream.
96 template<typename Stream, typename Ch>
97 inline void PutN(Stream& stream, Ch c, size_t n) {
98 PutReserve(stream, n);
99 for (size_t i = 0; i < n; i++)
100 PutUnsafe(stream, c);
101 }
102
103 ///////////////////////////////////////////////////////////////////////////////
104 // GenericStreamWrapper
105
106 //! A Stream Wrapper
107 /*! \tThis string stream is a wrapper for any stream by just forwarding any
108 \treceived message to the origin stream.
109 \note implements Stream concept
110 */
111
112 #if defined(_MSC_VER) && _MSC_VER <= 1800
113 RAPIDJSON_DIAG_PUSH
114 RAPIDJSON_DIAG_OFF(4702) // unreachable code
115 RAPIDJSON_DIAG_OFF(4512) // assignment operator could not be generated
116 #endif
117
118 template <typename InputStream, typename Encoding = UTF8<> >
119 class GenericStreamWrapper {
120 public:
121 typedef typename Encoding::Ch Ch;
122 GenericStreamWrapper(InputStream& is): is_(is) {}
123
124 Ch Peek() const { return is_.Peek(); }
125 Ch Take() { return is_.Take(); }
126 size_t Tell() { return is_.Tell(); }
127 Ch* PutBegin() { return is_.PutBegin(); }
128 void Put(Ch ch) { is_.Put(ch); }
129 void Flush() { is_.Flush(); }
130 size_t PutEnd(Ch* ch) { return is_.PutEnd(ch); }
131
132 // wrapper for MemoryStream
133 const Ch* Peek4() const { return is_.Peek4(); }
134
135 // wrapper for AutoUTFInputStream
136 UTFType GetType() const { return is_.GetType(); }
137 bool HasBOM() const { return is_.HasBOM(); }
138
139 protected:
140 InputStream& is_;
141 };
142
143 #if defined(_MSC_VER) && _MSC_VER <= 1800
144 RAPIDJSON_DIAG_POP
145 #endif
146
147 ///////////////////////////////////////////////////////////////////////////////
148 // StringStream
149
150 //! Read-only string stream.
151 /*! \note implements Stream concept
152 */
153 template <typename Encoding>
154 struct GenericStringStream {
155 typedef typename Encoding::Ch Ch;
156
157 GenericStringStream(const Ch *src) : src_(src), head_(src) {}
158
159 Ch Peek() const { return *src_; }
160 Ch Take() { return *src_++; }
161 size_t Tell() const { return static_cast<size_t>(src_ - head_); }
162
163 Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
164 void Put(Ch) { RAPIDJSON_ASSERT(false); }
165 void Flush() { RAPIDJSON_ASSERT(false); }
166 size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }
167
168 const Ch* src_; //!< Current read position.
169 const Ch* head_; //!< Original head of the string.
170 };
171
172 template <typename Encoding>
173 struct StreamTraits<GenericStringStream<Encoding> > {
174 enum { copyOptimization = 1 };
175 };
176
177 //! String stream with UTF8 encoding.
178 typedef GenericStringStream<UTF8<> > StringStream;
179
180 ///////////////////////////////////////////////////////////////////////////////
181 // InsituStringStream
182
183 //! A read-write string stream.
184 /*! This string stream is particularly designed for in-situ parsing.
185 \note implements Stream concept
186 */
187 template <typename Encoding>
188 struct GenericInsituStringStream {
189 typedef typename Encoding::Ch Ch;
190
191 GenericInsituStringStream(Ch *src) : src_(src), dst_(0), head_(src) {}
192
193 // Read
194 Ch Peek() { return *src_; }
195 Ch Take() { return *src_++; }
196 size_t Tell() { return static_cast<size_t>(src_ - head_); }
197
198 // Write
199 void Put(Ch c) { RAPIDJSON_ASSERT(dst_ != 0); *dst_++ = c; }
200
201 Ch* PutBegin() { return dst_ = src_; }
202 size_t PutEnd(Ch* begin) { return static_cast<size_t>(dst_ - begin); }
203 void Flush() {}
204
205 Ch* Push(size_t count) { Ch* begin = dst_; dst_ += count; return begin; }
206 void Pop(size_t count) { dst_ -= count; }
207
208 Ch* src_;
209 Ch* dst_;
210 Ch* head_;
211 };
212
213 template <typename Encoding>
214 struct StreamTraits<GenericInsituStringStream<Encoding> > {
215 enum { copyOptimization = 1 };
216 };
217
218 //! Insitu string stream with UTF8 encoding.
219 typedef GenericInsituStringStream<UTF8<> > InsituStringStream;
220
221 RAPIDJSON_NAMESPACE_END
222
223 #endif // RAPIDJSON_STREAM_H_
Stream
Concept for reading and writing characters.
rapidjson::GenericInsituStringStream
A read-write string stream.
Definition: stream.h:188
rapidjson.h
common definitions and configuration
rapidjson::StreamTraits
Provides additional information for stream.
Definition: stream.h:73
rapidjson::GenericStringStream
Read-only string stream.
Definition: stream.h:154
rapidjson::GenericStreamWrapper
A Stream Wrapper.
Definition: stream.h:119
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406
rapidjson::PutUnsafe
void PutUnsafe(Stream &stream, typename Stream::Ch c)
Write character to a stream, presuming buffer is reserved.
Definition: stream.h:91
rapidjson::UTFType
UTFType
Runtime-specified UTF encoding type of a stream.
Definition: encodings.h:603
rapidjson::PutReserve
void PutReserve(Stream &stream, size_t count)
Reserve n characters for writing to a stream.
Definition: stream.h:84
rapidjson::GenericStringStream::head_
const Ch * head_
Original head of the string.
Definition: stream.h:169
Encoding
Concept for encoding of Unicode characters.
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
rapidjson::GenericStringStream::src_
const Ch * src_
Current read position.
Definition: stream.h:168