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1 | // |
2 | // read.hpp | |
3 | // ~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com) | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_READ_HPP | |
12 | #define BOOST_ASIO_READ_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | #include <cstddef> | |
20 | #include <boost/asio/async_result.hpp> | |
21 | #include <boost/asio/basic_streambuf_fwd.hpp> | |
22 | #include <boost/asio/error.hpp> | |
23 | ||
24 | #include <boost/asio/detail/push_options.hpp> | |
25 | ||
26 | namespace boost { | |
27 | namespace asio { | |
28 | ||
29 | /** | |
30 | * @defgroup read boost::asio::read | |
31 | * | |
32 | * @brief Attempt to read a certain amount of data from a stream before | |
33 | * returning. | |
34 | */ | |
35 | /*@{*/ | |
36 | ||
37 | /// Attempt to read a certain amount of data from a stream before returning. | |
38 | /** | |
39 | * This function is used to read a certain number of bytes of data from a | |
40 | * stream. The call will block until one of the following conditions is true: | |
41 | * | |
42 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
43 | * the sum of the buffer sizes. | |
44 | * | |
45 | * @li An error occurred. | |
46 | * | |
47 | * This operation is implemented in terms of zero or more calls to the stream's | |
48 | * read_some function. | |
49 | * | |
50 | * @param s The stream from which the data is to be read. The type must support | |
51 | * the SyncReadStream concept. | |
52 | * | |
53 | * @param buffers One or more buffers into which the data will be read. The sum | |
54 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
55 | * stream. | |
56 | * | |
57 | * @returns The number of bytes transferred. | |
58 | * | |
59 | * @throws boost::system::system_error Thrown on failure. | |
60 | * | |
61 | * @par Example | |
62 | * To read into a single data buffer use the @ref buffer function as follows: | |
63 | * @code boost::asio::read(s, boost::asio::buffer(data, size)); @endcode | |
64 | * See the @ref buffer documentation for information on reading into multiple | |
65 | * buffers in one go, and how to use it with arrays, boost::array or | |
66 | * std::vector. | |
67 | * | |
68 | * @note This overload is equivalent to calling: | |
69 | * @code boost::asio::read( | |
70 | * s, buffers, | |
71 | * boost::asio::transfer_all()); @endcode | |
72 | */ | |
73 | template <typename SyncReadStream, typename MutableBufferSequence> | |
74 | std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers); | |
75 | ||
76 | /// Attempt to read a certain amount of data from a stream before returning. | |
77 | /** | |
78 | * This function is used to read a certain number of bytes of data from a | |
79 | * stream. The call will block until one of the following conditions is true: | |
80 | * | |
81 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
82 | * the sum of the buffer sizes. | |
83 | * | |
84 | * @li An error occurred. | |
85 | * | |
86 | * This operation is implemented in terms of zero or more calls to the stream's | |
87 | * read_some function. | |
88 | * | |
89 | * @param s The stream from which the data is to be read. The type must support | |
90 | * the SyncReadStream concept. | |
91 | * | |
92 | * @param buffers One or more buffers into which the data will be read. The sum | |
93 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
94 | * stream. | |
95 | * | |
96 | * @param ec Set to indicate what error occurred, if any. | |
97 | * | |
98 | * @returns The number of bytes transferred. | |
99 | * | |
100 | * @par Example | |
101 | * To read into a single data buffer use the @ref buffer function as follows: | |
102 | * @code boost::asio::read(s, boost::asio::buffer(data, size), ec); @endcode | |
103 | * See the @ref buffer documentation for information on reading into multiple | |
104 | * buffers in one go, and how to use it with arrays, boost::array or | |
105 | * std::vector. | |
106 | * | |
107 | * @note This overload is equivalent to calling: | |
108 | * @code boost::asio::read( | |
109 | * s, buffers, | |
110 | * boost::asio::transfer_all(), ec); @endcode | |
111 | */ | |
112 | template <typename SyncReadStream, typename MutableBufferSequence> | |
113 | std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, | |
114 | boost::system::error_code& ec); | |
115 | ||
116 | /// Attempt to read a certain amount of data from a stream before returning. | |
117 | /** | |
118 | * This function is used to read a certain number of bytes of data from a | |
119 | * stream. The call will block until one of the following conditions is true: | |
120 | * | |
121 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
122 | * the sum of the buffer sizes. | |
123 | * | |
124 | * @li The completion_condition function object returns 0. | |
125 | * | |
126 | * This operation is implemented in terms of zero or more calls to the stream's | |
127 | * read_some function. | |
128 | * | |
129 | * @param s The stream from which the data is to be read. The type must support | |
130 | * the SyncReadStream concept. | |
131 | * | |
132 | * @param buffers One or more buffers into which the data will be read. The sum | |
133 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
134 | * stream. | |
135 | * | |
136 | * @param completion_condition The function object to be called to determine | |
137 | * whether the read operation is complete. The signature of the function object | |
138 | * must be: | |
139 | * @code std::size_t completion_condition( | |
140 | * // Result of latest read_some operation. | |
141 | * const boost::system::error_code& error, | |
142 | * | |
143 | * // Number of bytes transferred so far. | |
144 | * std::size_t bytes_transferred | |
145 | * ); @endcode | |
146 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
147 | * return value indicates the maximum number of bytes to be read on the next | |
148 | * call to the stream's read_some function. | |
149 | * | |
150 | * @returns The number of bytes transferred. | |
151 | * | |
152 | * @throws boost::system::system_error Thrown on failure. | |
153 | * | |
154 | * @par Example | |
155 | * To read into a single data buffer use the @ref buffer function as follows: | |
156 | * @code boost::asio::read(s, boost::asio::buffer(data, size), | |
157 | * boost::asio::transfer_at_least(32)); @endcode | |
158 | * See the @ref buffer documentation for information on reading into multiple | |
159 | * buffers in one go, and how to use it with arrays, boost::array or | |
160 | * std::vector. | |
161 | */ | |
162 | template <typename SyncReadStream, typename MutableBufferSequence, | |
163 | typename CompletionCondition> | |
164 | std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, | |
165 | CompletionCondition completion_condition); | |
166 | ||
167 | /// Attempt to read a certain amount of data from a stream before returning. | |
168 | /** | |
169 | * This function is used to read a certain number of bytes of data from a | |
170 | * stream. The call will block until one of the following conditions is true: | |
171 | * | |
172 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
173 | * the sum of the buffer sizes. | |
174 | * | |
175 | * @li The completion_condition function object returns 0. | |
176 | * | |
177 | * This operation is implemented in terms of zero or more calls to the stream's | |
178 | * read_some function. | |
179 | * | |
180 | * @param s The stream from which the data is to be read. The type must support | |
181 | * the SyncReadStream concept. | |
182 | * | |
183 | * @param buffers One or more buffers into which the data will be read. The sum | |
184 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
185 | * stream. | |
186 | * | |
187 | * @param completion_condition The function object to be called to determine | |
188 | * whether the read operation is complete. The signature of the function object | |
189 | * must be: | |
190 | * @code std::size_t completion_condition( | |
191 | * // Result of latest read_some operation. | |
192 | * const boost::system::error_code& error, | |
193 | * | |
194 | * // Number of bytes transferred so far. | |
195 | * std::size_t bytes_transferred | |
196 | * ); @endcode | |
197 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
198 | * return value indicates the maximum number of bytes to be read on the next | |
199 | * call to the stream's read_some function. | |
200 | * | |
201 | * @param ec Set to indicate what error occurred, if any. | |
202 | * | |
203 | * @returns The number of bytes read. If an error occurs, returns the total | |
204 | * number of bytes successfully transferred prior to the error. | |
205 | */ | |
206 | template <typename SyncReadStream, typename MutableBufferSequence, | |
207 | typename CompletionCondition> | |
208 | std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers, | |
209 | CompletionCondition completion_condition, boost::system::error_code& ec); | |
210 | ||
211 | #if !defined(BOOST_ASIO_NO_IOSTREAM) | |
212 | ||
213 | /// Attempt to read a certain amount of data from a stream before returning. | |
214 | /** | |
215 | * This function is used to read a certain number of bytes of data from a | |
216 | * stream. The call will block until one of the following conditions is true: | |
217 | * | |
218 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
219 | * | |
220 | * @li An error occurred. | |
221 | * | |
222 | * This operation is implemented in terms of zero or more calls to the stream's | |
223 | * read_some function. | |
224 | * | |
225 | * @param s The stream from which the data is to be read. The type must support | |
226 | * the SyncReadStream concept. | |
227 | * | |
228 | * @param b The basic_streambuf object into which the data will be read. | |
229 | * | |
230 | * @returns The number of bytes transferred. | |
231 | * | |
232 | * @throws boost::system::system_error Thrown on failure. | |
233 | * | |
234 | * @note This overload is equivalent to calling: | |
235 | * @code boost::asio::read( | |
236 | * s, b, | |
237 | * boost::asio::transfer_all()); @endcode | |
238 | */ | |
239 | template <typename SyncReadStream, typename Allocator> | |
240 | std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b); | |
241 | ||
242 | /// Attempt to read a certain amount of data from a stream before returning. | |
243 | /** | |
244 | * This function is used to read a certain number of bytes of data from a | |
245 | * stream. The call will block until one of the following conditions is true: | |
246 | * | |
247 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
248 | * | |
249 | * @li An error occurred. | |
250 | * | |
251 | * This operation is implemented in terms of zero or more calls to the stream's | |
252 | * read_some function. | |
253 | * | |
254 | * @param s The stream from which the data is to be read. The type must support | |
255 | * the SyncReadStream concept. | |
256 | * | |
257 | * @param b The basic_streambuf object into which the data will be read. | |
258 | * | |
259 | * @param ec Set to indicate what error occurred, if any. | |
260 | * | |
261 | * @returns The number of bytes transferred. | |
262 | * | |
263 | * @note This overload is equivalent to calling: | |
264 | * @code boost::asio::read( | |
265 | * s, b, | |
266 | * boost::asio::transfer_all(), ec); @endcode | |
267 | */ | |
268 | template <typename SyncReadStream, typename Allocator> | |
269 | std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, | |
270 | boost::system::error_code& ec); | |
271 | ||
272 | /// Attempt to read a certain amount of data from a stream before returning. | |
273 | /** | |
274 | * This function is used to read a certain number of bytes of data from a | |
275 | * stream. The call will block until one of the following conditions is true: | |
276 | * | |
277 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
278 | * | |
279 | * @li The completion_condition function object returns 0. | |
280 | * | |
281 | * This operation is implemented in terms of zero or more calls to the stream's | |
282 | * read_some function. | |
283 | * | |
284 | * @param s The stream from which the data is to be read. The type must support | |
285 | * the SyncReadStream concept. | |
286 | * | |
287 | * @param b The basic_streambuf object into which the data will be read. | |
288 | * | |
289 | * @param completion_condition The function object to be called to determine | |
290 | * whether the read operation is complete. The signature of the function object | |
291 | * must be: | |
292 | * @code std::size_t completion_condition( | |
293 | * // Result of latest read_some operation. | |
294 | * const boost::system::error_code& error, | |
295 | * | |
296 | * // Number of bytes transferred so far. | |
297 | * std::size_t bytes_transferred | |
298 | * ); @endcode | |
299 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
300 | * return value indicates the maximum number of bytes to be read on the next | |
301 | * call to the stream's read_some function. | |
302 | * | |
303 | * @returns The number of bytes transferred. | |
304 | * | |
305 | * @throws boost::system::system_error Thrown on failure. | |
306 | */ | |
307 | template <typename SyncReadStream, typename Allocator, | |
308 | typename CompletionCondition> | |
309 | std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, | |
310 | CompletionCondition completion_condition); | |
311 | ||
312 | /// Attempt to read a certain amount of data from a stream before returning. | |
313 | /** | |
314 | * This function is used to read a certain number of bytes of data from a | |
315 | * stream. The call will block until one of the following conditions is true: | |
316 | * | |
317 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
318 | * | |
319 | * @li The completion_condition function object returns 0. | |
320 | * | |
321 | * This operation is implemented in terms of zero or more calls to the stream's | |
322 | * read_some function. | |
323 | * | |
324 | * @param s The stream from which the data is to be read. The type must support | |
325 | * the SyncReadStream concept. | |
326 | * | |
327 | * @param b The basic_streambuf object into which the data will be read. | |
328 | * | |
329 | * @param completion_condition The function object to be called to determine | |
330 | * whether the read operation is complete. The signature of the function object | |
331 | * must be: | |
332 | * @code std::size_t completion_condition( | |
333 | * // Result of latest read_some operation. | |
334 | * const boost::system::error_code& error, | |
335 | * | |
336 | * // Number of bytes transferred so far. | |
337 | * std::size_t bytes_transferred | |
338 | * ); @endcode | |
339 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
340 | * return value indicates the maximum number of bytes to be read on the next | |
341 | * call to the stream's read_some function. | |
342 | * | |
343 | * @param ec Set to indicate what error occurred, if any. | |
344 | * | |
345 | * @returns The number of bytes read. If an error occurs, returns the total | |
346 | * number of bytes successfully transferred prior to the error. | |
347 | */ | |
348 | template <typename SyncReadStream, typename Allocator, | |
349 | typename CompletionCondition> | |
350 | std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b, | |
351 | CompletionCondition completion_condition, boost::system::error_code& ec); | |
352 | ||
353 | #endif // !defined(BOOST_ASIO_NO_IOSTREAM) | |
354 | ||
355 | /*@}*/ | |
356 | /** | |
357 | * @defgroup async_read boost::asio::async_read | |
358 | * | |
359 | * @brief Start an asynchronous operation to read a certain amount of data from | |
360 | * a stream. | |
361 | */ | |
362 | /*@{*/ | |
363 | ||
364 | /// Start an asynchronous operation to read a certain amount of data from a | |
365 | /// stream. | |
366 | /** | |
367 | * This function is used to asynchronously read a certain number of bytes of | |
368 | * data from a stream. The function call always returns immediately. The | |
369 | * asynchronous operation will continue until one of the following conditions is | |
370 | * true: | |
371 | * | |
372 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
373 | * the sum of the buffer sizes. | |
374 | * | |
375 | * @li An error occurred. | |
376 | * | |
377 | * This operation is implemented in terms of zero or more calls to the stream's | |
378 | * async_read_some function, and is known as a <em>composed operation</em>. The | |
379 | * program must ensure that the stream performs no other read operations (such | |
380 | * as async_read, the stream's async_read_some function, or any other composed | |
381 | * operations that perform reads) until this operation completes. | |
382 | * | |
383 | * @param s The stream from which the data is to be read. The type must support | |
384 | * the AsyncReadStream concept. | |
385 | * | |
386 | * @param buffers One or more buffers into which the data will be read. The sum | |
387 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
388 | * stream. Although the buffers object may be copied as necessary, ownership of | |
389 | * the underlying memory blocks is retained by the caller, which must guarantee | |
390 | * that they remain valid until the handler is called. | |
391 | * | |
392 | * @param handler The handler to be called when the read operation completes. | |
393 | * Copies will be made of the handler as required. The function signature of the | |
394 | * handler must be: | |
395 | * @code void handler( | |
396 | * const boost::system::error_code& error, // Result of operation. | |
397 | * | |
398 | * std::size_t bytes_transferred // Number of bytes copied into the | |
399 | * // buffers. If an error occurred, | |
400 | * // this will be the number of | |
401 | * // bytes successfully transferred | |
402 | * // prior to the error. | |
403 | * ); @endcode | |
404 | * Regardless of whether the asynchronous operation completes immediately or | |
405 | * not, the handler will not be invoked from within this function. Invocation of | |
406 | * the handler will be performed in a manner equivalent to using | |
407 | * boost::asio::io_service::post(). | |
408 | * | |
409 | * @par Example | |
410 | * To read into a single data buffer use the @ref buffer function as follows: | |
411 | * @code | |
412 | * boost::asio::async_read(s, boost::asio::buffer(data, size), handler); | |
413 | * @endcode | |
414 | * See the @ref buffer documentation for information on reading into multiple | |
415 | * buffers in one go, and how to use it with arrays, boost::array or | |
416 | * std::vector. | |
417 | * | |
418 | * @note This overload is equivalent to calling: | |
419 | * @code boost::asio::async_read( | |
420 | * s, buffers, | |
421 | * boost::asio::transfer_all(), | |
422 | * handler); @endcode | |
423 | */ | |
424 | template <typename AsyncReadStream, typename MutableBufferSequence, | |
425 | typename ReadHandler> | |
426 | BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler, | |
427 | void (boost::system::error_code, std::size_t)) | |
428 | async_read(AsyncReadStream& s, const MutableBufferSequence& buffers, | |
429 | BOOST_ASIO_MOVE_ARG(ReadHandler) handler); | |
430 | ||
431 | /// Start an asynchronous operation to read a certain amount of data from a | |
432 | /// stream. | |
433 | /** | |
434 | * This function is used to asynchronously read a certain number of bytes of | |
435 | * data from a stream. The function call always returns immediately. The | |
436 | * asynchronous operation will continue until one of the following conditions is | |
437 | * true: | |
438 | * | |
439 | * @li The supplied buffers are full. That is, the bytes transferred is equal to | |
440 | * the sum of the buffer sizes. | |
441 | * | |
442 | * @li The completion_condition function object returns 0. | |
443 | * | |
444 | * @param s The stream from which the data is to be read. The type must support | |
445 | * the AsyncReadStream concept. | |
446 | * | |
447 | * @param buffers One or more buffers into which the data will be read. The sum | |
448 | * of the buffer sizes indicates the maximum number of bytes to read from the | |
449 | * stream. Although the buffers object may be copied as necessary, ownership of | |
450 | * the underlying memory blocks is retained by the caller, which must guarantee | |
451 | * that they remain valid until the handler is called. | |
452 | * | |
453 | * @param completion_condition The function object to be called to determine | |
454 | * whether the read operation is complete. The signature of the function object | |
455 | * must be: | |
456 | * @code std::size_t completion_condition( | |
457 | * // Result of latest async_read_some operation. | |
458 | * const boost::system::error_code& error, | |
459 | * | |
460 | * // Number of bytes transferred so far. | |
461 | * std::size_t bytes_transferred | |
462 | * ); @endcode | |
463 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
464 | * return value indicates the maximum number of bytes to be read on the next | |
465 | * call to the stream's async_read_some function. | |
466 | * | |
467 | * @param handler The handler to be called when the read operation completes. | |
468 | * Copies will be made of the handler as required. The function signature of the | |
469 | * handler must be: | |
470 | * @code void handler( | |
471 | * const boost::system::error_code& error, // Result of operation. | |
472 | * | |
473 | * std::size_t bytes_transferred // Number of bytes copied into the | |
474 | * // buffers. If an error occurred, | |
475 | * // this will be the number of | |
476 | * // bytes successfully transferred | |
477 | * // prior to the error. | |
478 | * ); @endcode | |
479 | * Regardless of whether the asynchronous operation completes immediately or | |
480 | * not, the handler will not be invoked from within this function. Invocation of | |
481 | * the handler will be performed in a manner equivalent to using | |
482 | * boost::asio::io_service::post(). | |
483 | * | |
484 | * @par Example | |
485 | * To read into a single data buffer use the @ref buffer function as follows: | |
486 | * @code boost::asio::async_read(s, | |
487 | * boost::asio::buffer(data, size), | |
488 | * boost::asio::transfer_at_least(32), | |
489 | * handler); @endcode | |
490 | * See the @ref buffer documentation for information on reading into multiple | |
491 | * buffers in one go, and how to use it with arrays, boost::array or | |
492 | * std::vector. | |
493 | */ | |
494 | template <typename AsyncReadStream, typename MutableBufferSequence, | |
495 | typename CompletionCondition, typename ReadHandler> | |
496 | BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler, | |
497 | void (boost::system::error_code, std::size_t)) | |
498 | async_read(AsyncReadStream& s, const MutableBufferSequence& buffers, | |
499 | CompletionCondition completion_condition, | |
500 | BOOST_ASIO_MOVE_ARG(ReadHandler) handler); | |
501 | ||
502 | #if !defined(BOOST_ASIO_NO_IOSTREAM) | |
503 | ||
504 | /// Start an asynchronous operation to read a certain amount of data from a | |
505 | /// stream. | |
506 | /** | |
507 | * This function is used to asynchronously read a certain number of bytes of | |
508 | * data from a stream. The function call always returns immediately. The | |
509 | * asynchronous operation will continue until one of the following conditions is | |
510 | * true: | |
511 | * | |
512 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
513 | * | |
514 | * @li An error occurred. | |
515 | * | |
516 | * This operation is implemented in terms of zero or more calls to the stream's | |
517 | * async_read_some function, and is known as a <em>composed operation</em>. The | |
518 | * program must ensure that the stream performs no other read operations (such | |
519 | * as async_read, the stream's async_read_some function, or any other composed | |
520 | * operations that perform reads) until this operation completes. | |
521 | * | |
522 | * @param s The stream from which the data is to be read. The type must support | |
523 | * the AsyncReadStream concept. | |
524 | * | |
525 | * @param b A basic_streambuf object into which the data will be read. Ownership | |
526 | * of the streambuf is retained by the caller, which must guarantee that it | |
527 | * remains valid until the handler is called. | |
528 | * | |
529 | * @param handler The handler to be called when the read operation completes. | |
530 | * Copies will be made of the handler as required. The function signature of the | |
531 | * handler must be: | |
532 | * @code void handler( | |
533 | * const boost::system::error_code& error, // Result of operation. | |
534 | * | |
535 | * std::size_t bytes_transferred // Number of bytes copied into the | |
536 | * // buffers. If an error occurred, | |
537 | * // this will be the number of | |
538 | * // bytes successfully transferred | |
539 | * // prior to the error. | |
540 | * ); @endcode | |
541 | * Regardless of whether the asynchronous operation completes immediately or | |
542 | * not, the handler will not be invoked from within this function. Invocation of | |
543 | * the handler will be performed in a manner equivalent to using | |
544 | * boost::asio::io_service::post(). | |
545 | * | |
546 | * @note This overload is equivalent to calling: | |
547 | * @code boost::asio::async_read( | |
548 | * s, b, | |
549 | * boost::asio::transfer_all(), | |
550 | * handler); @endcode | |
551 | */ | |
552 | template <typename AsyncReadStream, typename Allocator, typename ReadHandler> | |
553 | BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler, | |
554 | void (boost::system::error_code, std::size_t)) | |
555 | async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b, | |
556 | BOOST_ASIO_MOVE_ARG(ReadHandler) handler); | |
557 | ||
558 | /// Start an asynchronous operation to read a certain amount of data from a | |
559 | /// stream. | |
560 | /** | |
561 | * This function is used to asynchronously read a certain number of bytes of | |
562 | * data from a stream. The function call always returns immediately. The | |
563 | * asynchronous operation will continue until one of the following conditions is | |
564 | * true: | |
565 | * | |
566 | * @li The supplied buffer is full (that is, it has reached maximum size). | |
567 | * | |
568 | * @li The completion_condition function object returns 0. | |
569 | * | |
570 | * This operation is implemented in terms of zero or more calls to the stream's | |
571 | * async_read_some function, and is known as a <em>composed operation</em>. The | |
572 | * program must ensure that the stream performs no other read operations (such | |
573 | * as async_read, the stream's async_read_some function, or any other composed | |
574 | * operations that perform reads) until this operation completes. | |
575 | * | |
576 | * @param s The stream from which the data is to be read. The type must support | |
577 | * the AsyncReadStream concept. | |
578 | * | |
579 | * @param b A basic_streambuf object into which the data will be read. Ownership | |
580 | * of the streambuf is retained by the caller, which must guarantee that it | |
581 | * remains valid until the handler is called. | |
582 | * | |
583 | * @param completion_condition The function object to be called to determine | |
584 | * whether the read operation is complete. The signature of the function object | |
585 | * must be: | |
586 | * @code std::size_t completion_condition( | |
587 | * // Result of latest async_read_some operation. | |
588 | * const boost::system::error_code& error, | |
589 | * | |
590 | * // Number of bytes transferred so far. | |
591 | * std::size_t bytes_transferred | |
592 | * ); @endcode | |
593 | * A return value of 0 indicates that the read operation is complete. A non-zero | |
594 | * return value indicates the maximum number of bytes to be read on the next | |
595 | * call to the stream's async_read_some function. | |
596 | * | |
597 | * @param handler The handler to be called when the read operation completes. | |
598 | * Copies will be made of the handler as required. The function signature of the | |
599 | * handler must be: | |
600 | * @code void handler( | |
601 | * const boost::system::error_code& error, // Result of operation. | |
602 | * | |
603 | * std::size_t bytes_transferred // Number of bytes copied into the | |
604 | * // buffers. If an error occurred, | |
605 | * // this will be the number of | |
606 | * // bytes successfully transferred | |
607 | * // prior to the error. | |
608 | * ); @endcode | |
609 | * Regardless of whether the asynchronous operation completes immediately or | |
610 | * not, the handler will not be invoked from within this function. Invocation of | |
611 | * the handler will be performed in a manner equivalent to using | |
612 | * boost::asio::io_service::post(). | |
613 | */ | |
614 | template <typename AsyncReadStream, typename Allocator, | |
615 | typename CompletionCondition, typename ReadHandler> | |
616 | BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler, | |
617 | void (boost::system::error_code, std::size_t)) | |
618 | async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b, | |
619 | CompletionCondition completion_condition, | |
620 | BOOST_ASIO_MOVE_ARG(ReadHandler) handler); | |
621 | ||
622 | #endif // !defined(BOOST_ASIO_NO_IOSTREAM) | |
623 | ||
624 | /*@}*/ | |
625 | ||
626 | } // namespace asio | |
627 | } // namespace boost | |
628 | ||
629 | #include <boost/asio/detail/pop_options.hpp> | |
630 | ||
631 | #include <boost/asio/impl/read.hpp> | |
632 | ||
633 | #endif // BOOST_ASIO_READ_HPP |