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1 | // |
2 | // detail/consuming_buffers.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2017 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_DETAIL_CONSUMING_BUFFERS_HPP | |
12 | #define BOOST_ASIO_DETAIL_CONSUMING_BUFFERS_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/buffer.hpp> | |
21 | #include <boost/asio/detail/buffer_sequence_adapter.hpp> | |
22 | #include <boost/asio/detail/limits.hpp> | |
23 | ||
24 | #include <boost/asio/detail/push_options.hpp> | |
25 | ||
26 | namespace boost { | |
27 | namespace asio { | |
28 | namespace detail { | |
29 | ||
30 | // Helper template to determine the maximum number of prepared buffers. | |
31 | template <typename Buffers> | |
32 | struct prepared_buffers_max | |
33 | { | |
34 | enum { value = buffer_sequence_adapter_base::max_buffers }; | |
35 | }; | |
36 | ||
37 | template <typename Elem, std::size_t N> | |
38 | struct prepared_buffers_max<boost::array<Elem, N> > | |
39 | { | |
40 | enum { value = N }; | |
41 | }; | |
42 | ||
43 | #if defined(BOOST_ASIO_HAS_STD_ARRAY) | |
44 | ||
45 | template <typename Elem, std::size_t N> | |
46 | struct prepared_buffers_max<std::array<Elem, N> > | |
47 | { | |
48 | enum { value = N }; | |
49 | }; | |
50 | ||
51 | #endif // defined(BOOST_ASIO_HAS_STD_ARRAY) | |
52 | ||
53 | // A buffer sequence used to represent a subsequence of the buffers. | |
54 | template <typename Buffer, std::size_t MaxBuffers> | |
55 | struct prepared_buffers | |
56 | { | |
57 | typedef Buffer value_type; | |
58 | typedef const Buffer* const_iterator; | |
59 | ||
60 | enum { max_buffers = MaxBuffers < 16 ? MaxBuffers : 16 }; | |
61 | ||
62 | prepared_buffers() : count(0) {} | |
63 | const_iterator begin() const { return elems; } | |
64 | const_iterator end() const { return elems + count; } | |
65 | ||
66 | Buffer elems[max_buffers]; | |
67 | std::size_t count; | |
68 | }; | |
69 | ||
70 | // A proxy for a sub-range in a list of buffers. | |
71 | template <typename Buffer, typename Buffers, typename Buffer_Iterator> | |
72 | class consuming_buffers | |
73 | { | |
74 | public: | |
75 | typedef prepared_buffers<Buffer, prepared_buffers_max<Buffers>::value> | |
76 | prepared_buffers_type; | |
77 | ||
78 | // Construct to represent the entire list of buffers. | |
79 | explicit consuming_buffers(const Buffers& buffers) | |
80 | : buffers_(buffers), | |
81 | total_consumed_(0), | |
82 | next_elem_(0), | |
83 | next_elem_offset_(0) | |
84 | { | |
85 | using boost::asio::buffer_size; | |
86 | total_size_ = buffer_size(buffers); | |
87 | } | |
88 | ||
89 | // Determine if we are at the end of the buffers. | |
90 | bool empty() const | |
91 | { | |
92 | return total_consumed_ >= total_size_; | |
93 | } | |
94 | ||
95 | // Get the buffer for a single transfer, with a size. | |
96 | prepared_buffers_type prepare(std::size_t max_size) | |
97 | { | |
98 | prepared_buffers_type result; | |
99 | ||
100 | Buffer_Iterator next = boost::asio::buffer_sequence_begin(buffers_); | |
101 | Buffer_Iterator end = boost::asio::buffer_sequence_end(buffers_); | |
102 | ||
103 | std::advance(next, next_elem_); | |
104 | std::size_t elem_offset = next_elem_offset_; | |
105 | while (next != end && max_size > 0 && result.count < result.max_buffers) | |
106 | { | |
107 | Buffer next_buf = Buffer(*next) + elem_offset; | |
108 | result.elems[result.count] = boost::asio::buffer(next_buf, max_size); | |
109 | max_size -= result.elems[result.count].size(); | |
110 | elem_offset = 0; | |
111 | if (result.elems[result.count].size() > 0) | |
112 | ++result.count; | |
113 | ++next; | |
114 | } | |
115 | ||
116 | return result; | |
117 | } | |
118 | ||
119 | // Consume the specified number of bytes from the buffers. | |
120 | void consume(std::size_t size) | |
121 | { | |
122 | total_consumed_ += size; | |
123 | ||
124 | Buffer_Iterator next = boost::asio::buffer_sequence_begin(buffers_); | |
125 | Buffer_Iterator end = boost::asio::buffer_sequence_end(buffers_); | |
126 | ||
127 | std::advance(next, next_elem_); | |
128 | while (next != end && size > 0) | |
129 | { | |
130 | Buffer next_buf = Buffer(*next) + next_elem_offset_; | |
131 | if (size < next_buf.size()) | |
132 | { | |
133 | next_elem_offset_ += size; | |
134 | size = 0; | |
135 | } | |
136 | else | |
137 | { | |
138 | size -= next_buf.size(); | |
139 | next_elem_offset_ = 0; | |
140 | ++next_elem_; | |
141 | ++next; | |
142 | } | |
143 | } | |
144 | } | |
145 | ||
146 | // Get the total number of bytes consumed from the buffers. | |
147 | std::size_t total_consumed() const | |
148 | { | |
149 | return total_consumed_; | |
150 | } | |
151 | ||
152 | private: | |
153 | Buffers buffers_; | |
154 | std::size_t total_size_; | |
155 | std::size_t total_consumed_; | |
156 | std::size_t next_elem_; | |
157 | std::size_t next_elem_offset_; | |
158 | }; | |
159 | ||
160 | // Base class of all consuming_buffers specialisations for single buffers. | |
161 | template <typename Buffer> | |
162 | class consuming_single_buffer | |
163 | { | |
164 | public: | |
165 | // Construct to represent the entire list of buffers. | |
166 | template <typename Buffer1> | |
167 | explicit consuming_single_buffer(const Buffer1& buffer) | |
168 | : buffer_(buffer), | |
169 | total_consumed_(0) | |
170 | { | |
171 | } | |
172 | ||
173 | // Determine if we are at the end of the buffers. | |
174 | bool empty() const | |
175 | { | |
176 | return total_consumed_ >= buffer_.size(); | |
177 | } | |
178 | ||
179 | // Get the buffer for a single transfer, with a size. | |
180 | Buffer prepare(std::size_t max_size) | |
181 | { | |
182 | return boost::asio::buffer(buffer_ + total_consumed_, max_size); | |
183 | } | |
184 | ||
185 | // Consume the specified number of bytes from the buffers. | |
186 | void consume(std::size_t size) | |
187 | { | |
188 | total_consumed_ += size; | |
189 | } | |
190 | ||
191 | // Get the total number of bytes consumed from the buffers. | |
192 | std::size_t total_consumed() const | |
193 | { | |
194 | return total_consumed_; | |
195 | } | |
196 | ||
197 | private: | |
198 | Buffer buffer_; | |
199 | std::size_t total_consumed_; | |
200 | }; | |
201 | ||
202 | template <> | |
203 | class consuming_buffers<mutable_buffer, mutable_buffer, const mutable_buffer*> | |
204 | : public consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER> | |
205 | { | |
206 | public: | |
207 | explicit consuming_buffers(const mutable_buffer& buffer) | |
208 | : consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>(buffer) | |
209 | { | |
210 | } | |
211 | }; | |
212 | ||
213 | template <> | |
214 | class consuming_buffers<const_buffer, mutable_buffer, const mutable_buffer*> | |
215 | : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER> | |
216 | { | |
217 | public: | |
218 | explicit consuming_buffers(const mutable_buffer& buffer) | |
219 | : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer) | |
220 | { | |
221 | } | |
222 | }; | |
223 | ||
224 | template <> | |
225 | class consuming_buffers<const_buffer, const_buffer, const const_buffer*> | |
226 | : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER> | |
227 | { | |
228 | public: | |
229 | explicit consuming_buffers(const const_buffer& buffer) | |
230 | : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer) | |
231 | { | |
232 | } | |
233 | }; | |
234 | ||
235 | #if !defined(BOOST_ASIO_NO_DEPRECATED) | |
236 | ||
237 | template <> | |
238 | class consuming_buffers<mutable_buffer, | |
239 | mutable_buffers_1, const mutable_buffer*> | |
240 | : public consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER> | |
241 | { | |
242 | public: | |
243 | explicit consuming_buffers(const mutable_buffers_1& buffer) | |
244 | : consuming_single_buffer<BOOST_ASIO_MUTABLE_BUFFER>(buffer) | |
245 | { | |
246 | } | |
247 | }; | |
248 | ||
249 | template <> | |
250 | class consuming_buffers<const_buffer, mutable_buffers_1, const mutable_buffer*> | |
251 | : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER> | |
252 | { | |
253 | public: | |
254 | explicit consuming_buffers(const mutable_buffers_1& buffer) | |
255 | : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer) | |
256 | { | |
257 | } | |
258 | }; | |
259 | ||
260 | template <> | |
261 | class consuming_buffers<const_buffer, const_buffers_1, const const_buffer*> | |
262 | : public consuming_single_buffer<BOOST_ASIO_CONST_BUFFER> | |
263 | { | |
264 | public: | |
265 | explicit consuming_buffers(const const_buffers_1& buffer) | |
266 | : consuming_single_buffer<BOOST_ASIO_CONST_BUFFER>(buffer) | |
267 | { | |
268 | } | |
269 | }; | |
270 | ||
271 | #endif // !defined(BOOST_ASIO_NO_DEPRECATED) | |
272 | ||
273 | template <typename Buffer, typename Elem> | |
274 | class consuming_buffers<Buffer, boost::array<Elem, 2>, | |
275 | typename boost::array<Elem, 2>::const_iterator> | |
276 | { | |
277 | public: | |
278 | // Construct to represent the entire list of buffers. | |
279 | explicit consuming_buffers(const boost::array<Elem, 2>& buffers) | |
280 | : buffers_(buffers), | |
281 | total_consumed_(0) | |
282 | { | |
283 | } | |
284 | ||
285 | // Determine if we are at the end of the buffers. | |
286 | bool empty() const | |
287 | { | |
288 | return total_consumed_ >= | |
289 | Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size(); | |
290 | } | |
291 | ||
292 | // Get the buffer for a single transfer, with a size. | |
293 | boost::array<Buffer, 2> prepare(std::size_t max_size) | |
294 | { | |
295 | boost::array<Buffer, 2> result = {{ | |
296 | Buffer(buffers_[0]), Buffer(buffers_[1]) }}; | |
297 | std::size_t buffer0_size = result[0].size(); | |
298 | result[0] = boost::asio::buffer(result[0] + total_consumed_, max_size); | |
299 | result[1] = boost::asio::buffer( | |
300 | result[1] + (total_consumed_ < buffer0_size | |
301 | ? 0 : total_consumed_ - buffer0_size), | |
302 | max_size - result[0].size()); | |
303 | return result; | |
304 | } | |
305 | ||
306 | // Consume the specified number of bytes from the buffers. | |
307 | void consume(std::size_t size) | |
308 | { | |
309 | total_consumed_ += size; | |
310 | } | |
311 | ||
312 | // Get the total number of bytes consumed from the buffers. | |
313 | std::size_t total_consumed() const | |
314 | { | |
315 | return total_consumed_; | |
316 | } | |
317 | ||
318 | private: | |
319 | boost::array<Elem, 2> buffers_; | |
320 | std::size_t total_consumed_; | |
321 | }; | |
322 | ||
323 | #if defined(BOOST_ASIO_HAS_STD_ARRAY) | |
324 | ||
325 | template <typename Buffer, typename Elem> | |
326 | class consuming_buffers<Buffer, std::array<Elem, 2>, | |
327 | typename std::array<Elem, 2>::const_iterator> | |
328 | { | |
329 | public: | |
330 | // Construct to represent the entire list of buffers. | |
331 | explicit consuming_buffers(const std::array<Elem, 2>& buffers) | |
332 | : buffers_(buffers), | |
333 | total_consumed_(0) | |
334 | { | |
335 | } | |
336 | ||
337 | // Determine if we are at the end of the buffers. | |
338 | bool empty() const | |
339 | { | |
340 | return total_consumed_ >= | |
341 | Buffer(buffers_[0]).size() + Buffer(buffers_[1]).size(); | |
342 | } | |
343 | ||
344 | // Get the buffer for a single transfer, with a size. | |
345 | std::array<Buffer, 2> prepare(std::size_t max_size) | |
346 | { | |
347 | std::array<Buffer, 2> result = {{ | |
348 | Buffer(buffers_[0]), Buffer(buffers_[1]) }}; | |
349 | std::size_t buffer0_size = result[0].size(); | |
350 | result[0] = boost::asio::buffer(result[0] + total_consumed_, max_size); | |
351 | result[1] = boost::asio::buffer( | |
352 | result[1] + (total_consumed_ < buffer0_size | |
353 | ? 0 : total_consumed_ - buffer0_size), | |
354 | max_size - result[0].size()); | |
355 | return result; | |
356 | } | |
357 | ||
358 | // Consume the specified number of bytes from the buffers. | |
359 | void consume(std::size_t size) | |
360 | { | |
361 | total_consumed_ += size; | |
362 | } | |
363 | ||
364 | // Get the total number of bytes consumed from the buffers. | |
365 | std::size_t total_consumed() const | |
366 | { | |
367 | return total_consumed_; | |
368 | } | |
369 | ||
370 | private: | |
371 | std::array<Elem, 2> buffers_; | |
372 | std::size_t total_consumed_; | |
373 | }; | |
374 | ||
375 | #endif // defined(BOOST_ASIO_HAS_STD_ARRAY) | |
376 | ||
377 | // Specialisation for null_buffers to ensure that the null_buffers type is | |
378 | // always passed through to the underlying read or write operation. | |
379 | template <typename Buffer> | |
380 | class consuming_buffers<Buffer, null_buffers, const mutable_buffer*> | |
381 | : public boost::asio::null_buffers | |
382 | { | |
383 | public: | |
384 | consuming_buffers(const null_buffers&) | |
385 | { | |
386 | // No-op. | |
387 | } | |
388 | ||
389 | bool empty() | |
390 | { | |
391 | return false; | |
392 | } | |
393 | ||
394 | null_buffers prepare(std::size_t) | |
395 | { | |
396 | return null_buffers(); | |
397 | } | |
398 | ||
399 | void consume(std::size_t) | |
400 | { | |
401 | // No-op. | |
402 | } | |
403 | ||
404 | std::size_t total_consume() const | |
405 | { | |
406 | return 0; | |
407 | } | |
408 | }; | |
409 | ||
410 | } // namespace detail | |
411 | } // namespace asio | |
412 | } // namespace boost | |
413 | ||
414 | #include <boost/asio/detail/pop_options.hpp> | |
415 | ||
416 | #endif // BOOST_ASIO_DETAIL_CONSUMING_BUFFERS_HPP |