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include/boost/capy/read.hpp

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read.hpp
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boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::mutable_buffer>(boost::capy::test::read_stream&, boost::capy::mutable_buffer) :91 22x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, std::array<boost::capy::mutable_buffer, 2ul> >(boost::capy::test::read_stream&, std::array<boost::capy::mutable_buffer, 2ul>) :91 34x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::stream, boost::capy::mutable_buffer>(boost::capy::test::stream&, boost::capy::mutable_buffer) :91 38x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&>(boost::capy::test::read_stream&, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&, unsigned long) :165 50x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_stream, boost::capy::circular_dynamic_buffer&>(boost::capy::test::read_stream&, boost::capy::circular_dynamic_buffer&, unsigned long) :165 30x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_source, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&>(boost::capy::test::read_source&, boost::capy::basic_string_dynamic_buffer<char, std::char_traits<char>, std::allocator<char> >&, unsigned long) :246 30x 100.0% 44.0% boost::capy::task<boost::capy::io_result<unsigned long> > boost::capy::read<boost::capy::test::read_source, boost::capy::circular_dynamic_buffer&>(boost::capy::test::read_source&, boost::capy::circular_dynamic_buffer&, unsigned long) :246 24x 100.0% 44.0%
Line TLA Hits Source Code
1 //
2 // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // Official repository: https://github.com/cppalliance/capy
8 //
9
10 #ifndef BOOST_CAPY_READ_HPP
11 #define BOOST_CAPY_READ_HPP
12
13 #include <boost/capy/detail/config.hpp>
14 #include <boost/capy/cond.hpp>
15 #include <boost/capy/io_task.hpp>
16 #include <boost/capy/buffers.hpp>
17 #include <boost/capy/buffers/buffer_slice.hpp>
18 #include <boost/capy/concept/dynamic_buffer.hpp>
19 #include <boost/capy/concept/read_source.hpp>
20 #include <boost/capy/concept/read_stream.hpp>
21 #include <system_error>
22
23 #include <cstddef>
24
25 namespace boost {
26 namespace capy {
27
28 /** Read data from a stream until the buffer sequence is full.
29
30 @par Await-effects
31
32 Reads data from `stream` via awaiting `stream.read_some` repeatedly
33 until:
34
35 @li either the entire buffer sequence @c buffers is filled,
36 @li or a contingency occurs.
37
38 If `buffer_size(buffers) == 0` then no awaiting `stream.read_some`
39 is performed. This is not a contingency.
40
41 @par Await-returns
42 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
43
44 Upon a contingency, `n` represents the number of bytes read so far,
45 inclusive of the last partial read.
46
47 Contingencies:
48
49 @li The first contingency reported from awaiting @c stream.read_some .
50
51 Notable conditions:
52
53 @li @c cond::canceled — Operation was cancelled,
54 @li @c cond::eof — Stream reached end before `buffers` was filled.
55
56 @par Await-postcondition
57 `ec || n == buffer_size(buffers)`.
58
59 @param stream The stream to read from. If the lifetime of `stream` ends
60 before the coroutine finishes, the behavior is undefined.
61
62 @param buffers The buffer sequence to fill. If the lifetime of the buffer
63 sequence represented by `buffers` ends before the coroutine finishes, the behavior is undefined.
64
65
66 @par Remarks
67 Supports _IoAwaitable cancellation_.
68
69
70 @par Example
71
72 @code
73 capy::task<> process_message(capy::ReadStream auto& stream)
74 {
75 std::vector<char> header(16); // known header size for some protocol
76 auto [ec, n] = co_await capy::read(stream, capy::mutable_buffer(header));
77 if (ec == capy::cond::eof)
78 co_return; // Connection closed
79 if (ec)
80 throw std::system_error(ec);
81
82 // at this point `header` contains exactly 16 bytes
83 }
84 @endcode
85
86 @see ReadStream, MutableBufferSequence
87 */
88 template <typename S, typename MB>
89 requires ReadStream<S> && MutableBufferSequence<MB>
90 auto
91 94x read(S& stream, MB buffers) ->
92 io_task<std::size_t>
93 {
94 auto consuming = buffer_slice(buffers);
95 std::size_t const total_size = buffer_size(buffers);
96 std::size_t total_read = 0;
97
98 while(total_read < total_size)
99 {
100 auto [ec, n] = co_await stream.read_some(consuming.data());
101 consuming.remove_prefix(n);
102 total_read += n;
103 if(ec)
104 co_return {ec, total_read};
105 }
106
107 co_return {{}, total_read};
108 188x }
109
110 /** Read all data from a stream into a dynamic buffer.
111
112 @par Await-effects
113
114 Reads data from `stream` via awaiting `stream.read_some` repeatedly
115 and appending the results to `dynbuf`,
116 until a contingency occurs.
117
118 Data is appended using prepare/commit semantics.
119 The buffer grows with 1.5x factor when filled.
120
121 @par Await-returns
122
123 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
124
125 `n` represents the total number of bytes read,
126 inclusive of the last partial read.
127
128 Contingencies:
129
130 @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
131
132 @par Await-throws
133 `std::bad_alloc` when append to `dynbuf` fails.
134
135 @param stream The stream to read from. If the lifetime of `stream` ends
136 before the coroutine finishes, the behavior is undefined.
137
138 @param dynbuf The dynamic buffer to append data to. If the lifetime of the buffer
139 sequence represented by `dynbuf` ends before the coroutine finishes, the behavior is undefined.
140
141 @param initial_amount Initial bytes to prepare (default 2048).
142
143
144 @par Remarks
145 Supports _IoAwaitable cancellation_.
146
147 @par Example
148
149 @code
150 capy::task<std::string> read_body(capy::ReadStream auto& stream)
151 {
152 std::string body;
153 auto [ec, n] = co_await capy::read(stream, capy::dynamic_buffer(body));
154 if (ec)
155 throw std::system_error(ec);
156 return body;
157 }
158 @endcode
159
160 @see read_some, ReadStream, DynamicBufferParam
161 */
162 template <typename S, typename DB>
163 requires ReadStream<S> && DynamicBufferParam<DB>
164 auto
165 80x read(
166 S& stream,
167 DB&& dynbuf,
168 std::size_t initial_amount = 2048) ->
169 io_task<std::size_t>
170 {
171 std::size_t amount = initial_amount;
172 std::size_t total_read = 0;
173 for(;;)
174 {
175 auto mb = dynbuf.prepare(amount);
176 auto const mb_size = buffer_size(mb);
177 auto [ec, n] = co_await stream.read_some(mb);
178 dynbuf.commit(n);
179 total_read += n;
180 if(ec == cond::eof)
181 co_return {{}, total_read};
182 if(ec)
183 co_return {ec, total_read};
184 if(n == mb_size)
185 amount = amount / 2 + amount;
186 }
187 160x }
188
189 /** Read all data from a source into a dynamic buffer.
190
191 @par Await-effects
192
193 Reads data from `stream` by calling `source.read` repeatedly
194 and appending it to `dynbuf` until a contingency occurs.
195 The last, potenitally partial, read is also appended.
196
197 Data is appended using prepare/commit semantics.
198 The buffer grows with 1.5x factor when filled.
199
200 @par Await-returns
201
202 An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
203
204 `n` represents the total number of bytes read,
205 inclusive of the last partial read.
206
207
208 Contingencies:
209
210 @li The first contingency, other than one matching to @c cond::eof, reported from awaiting @c stream.read_some .
211
212 @par Await-throws
213
214 `std::bad_alloc` when append to `dynbuf` fails.
215
216 @param source The source to read from. If the lifetime of `source` ends
217 before the coroutine finishes, the behavior is undefined.
218
219 @param dynbuf The dynamic buffer to append data to. If the lifetime of the
220 buffer sequence represented by `dynbuf` ends before the coroutine finishes,
221 the behavior is undefined.
222
223 @param initial_amount Initial bytes to prepare (default 2048).
224
225 @par Remarks
226 Supports _IoAwaitable cancellation_.
227
228 @par Example
229
230 @code
231 capy::task<std::string> read_body(capy::ReadSource auto& source)
232 {
233 std::string body;
234 auto [ec, n] = co_await capy::read(source, capy::dynamic_buffer(body));
235 if (ec)
236 throw std::system_error(ec);
237 return body;
238 }
239 @endcode
240
241 @see ReadSource, DynamicBufferParam
242 */
243 template <typename S, typename DB>
244 requires ReadSource<S> && DynamicBufferParam<DB>
245 auto
246 54x read(
247 S& source,
248 DB&& dynbuf,
249 std::size_t initial_amount = 2048) ->
250 io_task<std::size_t>
251 {
252 std::size_t amount = initial_amount;
253 std::size_t total_read = 0;
254 for(;;)
255 {
256 auto mb = dynbuf.prepare(amount);
257 auto const mb_size = buffer_size(mb);
258 auto [ec, n] = co_await source.read(mb);
259 dynbuf.commit(n);
260 total_read += n;
261 if(ec == cond::eof)
262 co_return {{}, total_read};
263 if(ec)
264 co_return {ec, total_read};
265 if(n == mb_size)
266 amount = amount / 2 + amount; // 1.5x growth
267 }
268 108x }
269
270 } // namespace capy
271 } // namespace boost
272
273 #endif
274