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24 | </div> | |
25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h4 class="title"> | |
27 | <a name="fiber.synchronization.futures.promise"></a><a name="class_promise"></a><a class="link" href="promise.html" title="Template promise<>">Template | |
28 | <code class="computeroutput"><span class="identifier">promise</span><span class="special"><></span></code></a> | |
29 | </h4></div></div></div> | |
30 | <p> | |
31 | A <a class="link" href="promise.html#class_promise"><code class="computeroutput">promise<></code></a> provides a mechanism to store a value (or | |
32 | exception) that can later be retrieved from the corresponding <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a> object. | |
33 | <code class="computeroutput"><span class="identifier">promise</span><span class="special"><></span></code> | |
34 | and <code class="computeroutput"><span class="identifier">future</span><span class="special"><></span></code> | |
35 | communicate via their underlying <a class="link" href="future.html#shared_state">shared state</a>. | |
36 | </p> | |
37 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fiber</span><span class="special">/</span><span class="identifier">future</span><span class="special">/</span><span class="identifier">promise</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> | |
38 | ||
39 | <span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> | |
40 | <span class="keyword">namespace</span> <span class="identifier">fibers</span> <span class="special">{</span> | |
41 | ||
42 | <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> | |
43 | <span class="keyword">class</span> <span class="identifier">promise</span> <span class="special">{</span> | |
44 | <span class="keyword">public</span><span class="special">:</span> | |
45 | <span class="identifier">promise</span><span class="special">();</span> | |
46 | ||
47 | <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a href="http://en.cppreference.com/w/cpp/concept/Allocator" target="_top"><code class="computeroutput"><span class="identifier">Allocator</span></code></a> <span class="special">></span> | |
48 | <span class="identifier">promise</span><span class="special">(</span> <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a><span class="special">,</span> <span class="identifier">Allocator</span><span class="special">);</span> | |
49 | ||
50 | <span class="identifier">promise</span><span class="special">(</span> <span class="identifier">promise</span> <span class="special">&&)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
51 | ||
52 | <span class="identifier">promise</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">promise</span> <span class="special">&&)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
53 | ||
54 | <span class="identifier">promise</span><span class="special">(</span> <span class="identifier">promise</span> <span class="keyword">const</span><span class="special">&)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span> | |
55 | ||
56 | <span class="identifier">promise</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">promise</span> <span class="keyword">const</span><span class="special">&)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span> | |
57 | ||
58 | <span class="special">~</span><span class="identifier">promise</span><span class="special">();</span> | |
59 | ||
60 | <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">promise</span> <span class="special">&)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
61 | ||
62 | <span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="identifier">get_future</span><span class="special">();</span> | |
63 | ||
64 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="keyword">const</span><span class="special">&);</span> <span class="comment">// member only of generic promise template</span> | |
65 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="special">&&);</span> <span class="comment">// member only of generic promise template</span> | |
66 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="special">&);</span> <span class="comment">// member only of promise< R & > template</span> | |
67 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">();</span> <span class="comment">// member only of promise< void > template</span> | |
68 | ||
69 | <span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">p</span><span class="special">);</span> | |
70 | <span class="special">};</span> | |
71 | ||
72 | <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> | |
73 | <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">promise</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&,</span> <span class="identifier">promise</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
74 | ||
75 | <span class="special">}</span> | |
76 | </pre> | |
77 | <h6> | |
78 | <a name="fiber.synchronization.futures.promise.h0"></a> | |
79 | <span><a name="fiber.synchronization.futures.promise.default_constructor"></a></span><a class="link" href="promise.html#fiber.synchronization.futures.promise.default_constructor">Default | |
80 | constructor</a> | |
81 | </h6> | |
82 | <pre class="programlisting"><span class="identifier">promise</span><span class="special">();</span> | |
83 | </pre> | |
84 | <div class="variablelist"> | |
85 | <p class="title"><b></b></p> | |
86 | <dl> | |
87 | <dt><span class="term">Effects:</span></dt> | |
88 | <dd><p> | |
89 | Creates a promise with an empty <a class="link" href="future.html#shared_state">shared | |
90 | state</a>. | |
91 | </p></dd> | |
92 | <dt><span class="term">Throws:</span></dt> | |
93 | <dd><p> | |
94 | Exceptions caused by memory allocation. | |
95 | </p></dd> | |
96 | </dl> | |
97 | </div> | |
98 | <h6> | |
99 | <a name="fiber.synchronization.futures.promise.h1"></a> | |
100 | <span><a name="fiber.synchronization.futures.promise.constructor"></a></span><a class="link" href="promise.html#fiber.synchronization.futures.promise.constructor">Constructor</a> | |
101 | </h6> | |
102 | <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a href="http://en.cppreference.com/w/cpp/concept/Allocator" target="_top"><code class="computeroutput"><span class="identifier">Allocator</span></code></a> <span class="special">></span> | |
103 | <span class="identifier">promise</span><span class="special">(</span> <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">alloc</span><span class="special">);</span> | |
104 | </pre> | |
105 | <div class="variablelist"> | |
106 | <p class="title"><b></b></p> | |
107 | <dl> | |
108 | <dt><span class="term">Effects:</span></dt> | |
109 | <dd><p> | |
110 | Creates a promise with an empty <a class="link" href="future.html#shared_state">shared | |
111 | state</a> by using <code class="computeroutput"><span class="identifier">alloc</span></code>. | |
112 | </p></dd> | |
113 | <dt><span class="term">Throws:</span></dt> | |
114 | <dd><p> | |
115 | Exceptions caused by memory allocation. | |
116 | </p></dd> | |
117 | <dt><span class="term">See also:</span></dt> | |
118 | <dd><p> | |
119 | <a href="http://en.cppreference.com/w/cpp/memory/allocator_arg_t" target="_top"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">allocator_arg_t</span></code></a> | |
120 | </p></dd> | |
121 | </dl> | |
122 | </div> | |
123 | <h6> | |
124 | <a name="fiber.synchronization.futures.promise.h2"></a> | |
125 | <span><a name="fiber.synchronization.futures.promise.move_constructor"></a></span><a class="link" href="promise.html#fiber.synchronization.futures.promise.move_constructor">Move constructor</a> | |
126 | </h6> | |
127 | <pre class="programlisting"><span class="identifier">promise</span><span class="special">(</span> <span class="identifier">promise</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
128 | </pre> | |
129 | <div class="variablelist"> | |
130 | <p class="title"><b></b></p> | |
131 | <dl> | |
132 | <dt><span class="term">Effects:</span></dt> | |
133 | <dd><p> | |
134 | Creates a promise by moving the <a class="link" href="future.html#shared_state">shared | |
135 | state</a> from <code class="computeroutput"><span class="identifier">other</span></code>. | |
136 | </p></dd> | |
137 | <dt><span class="term">Postcondition:</span></dt> | |
138 | <dd><p> | |
139 | <code class="computeroutput"><span class="identifier">other</span></code> contains no | |
140 | valid shared state. | |
141 | </p></dd> | |
142 | <dt><span class="term">Throws:</span></dt> | |
143 | <dd><p> | |
144 | Nothing. | |
145 | </p></dd> | |
146 | </dl> | |
147 | </div> | |
148 | <h6> | |
149 | <a name="fiber.synchronization.futures.promise.h3"></a> | |
150 | <span><a name="fiber.synchronization.futures.promise.destructor"></a></span><a class="link" href="promise.html#fiber.synchronization.futures.promise.destructor">Destructor</a> | |
151 | </h6> | |
152 | <pre class="programlisting"><span class="special">~</span><span class="identifier">promise</span><span class="special">();</span> | |
153 | </pre> | |
154 | <div class="variablelist"> | |
155 | <p class="title"><b></b></p> | |
156 | <dl> | |
157 | <dt><span class="term">Effects:</span></dt> | |
158 | <dd><p> | |
159 | Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> | |
160 | and abandons the <a class="link" href="future.html#shared_state">shared state</a> | |
161 | if shared state is ready; otherwise stores <code class="computeroutput"><span class="identifier">future_error</span></code> | |
162 | with error condition <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span></code> | |
163 | as if by <a class="link" href="promise.html#promise_set_exception"><code class="computeroutput">promise::set_exception()</code></a>: the shared | |
164 | state is set ready. | |
165 | </p></dd> | |
166 | </dl> | |
167 | </div> | |
168 | <p> | |
169 | </p> | |
170 | <h5> | |
171 | <a name="promise_operator_assign_bridgehead"></a> | |
172 | <span><a name="promise_operator_assign"></a></span> | |
173 | <a class="link" href="promise.html#promise_operator_assign">Member | |
174 | function <code class="computeroutput">operator=</code>()</a> | |
175 | </h5> | |
176 | <p> | |
177 | </p> | |
178 | <pre class="programlisting"><span class="identifier">promise</span> <span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">promise</span> <span class="special">&&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
179 | </pre> | |
180 | <div class="variablelist"> | |
181 | <p class="title"><b></b></p> | |
182 | <dl> | |
183 | <dt><span class="term">Effects:</span></dt> | |
184 | <dd><p> | |
185 | Transfers the ownership of <a class="link" href="future.html#shared_state">shared state</a> | |
186 | to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. | |
187 | </p></dd> | |
188 | <dt><span class="term">Postcondition:</span></dt> | |
189 | <dd><p> | |
190 | <code class="computeroutput"><span class="identifier">other</span></code> contains no | |
191 | valid shared state. | |
192 | </p></dd> | |
193 | <dt><span class="term">Throws:</span></dt> | |
194 | <dd><p> | |
195 | Nothing. | |
196 | </p></dd> | |
197 | </dl> | |
198 | </div> | |
199 | <p> | |
200 | </p> | |
201 | <h5> | |
202 | <a name="promise_swap_bridgehead"></a> | |
203 | <span><a name="promise_swap"></a></span> | |
204 | <a class="link" href="promise.html#promise_swap">Member function <code class="computeroutput">swap</code>()</a> | |
205 | </h5> | |
206 | <p> | |
207 | </p> | |
208 | <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">promise</span> <span class="special">&</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
209 | </pre> | |
210 | <div class="variablelist"> | |
211 | <p class="title"><b></b></p> | |
212 | <dl> | |
213 | <dt><span class="term">Effects:</span></dt> | |
214 | <dd><p> | |
215 | Swaps the <a class="link" href="future.html#shared_state">shared state</a> between | |
216 | other and <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. | |
217 | </p></dd> | |
218 | <dt><span class="term">Throws:</span></dt> | |
219 | <dd><p> | |
220 | Nothing. | |
221 | </p></dd> | |
222 | </dl> | |
223 | </div> | |
224 | <p> | |
225 | </p> | |
226 | <h5> | |
227 | <a name="promise_get_future_bridgehead"></a> | |
228 | <span><a name="promise_get_future"></a></span> | |
229 | <a class="link" href="promise.html#promise_get_future">Member | |
230 | function <code class="computeroutput">get_future</code>()</a> | |
231 | </h5> | |
232 | <p> | |
233 | </p> | |
234 | <pre class="programlisting"><span class="identifier">future</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="identifier">get_future</span><span class="special">();</span> | |
235 | </pre> | |
236 | <div class="variablelist"> | |
237 | <p class="title"><b></b></p> | |
238 | <dl> | |
239 | <dt><span class="term">Returns:</span></dt> | |
240 | <dd><p> | |
241 | A <a class="link" href="future.html#class_future"><code class="computeroutput">future<></code></a> with the same <a class="link" href="future.html#shared_state">shared | |
242 | state</a>. | |
243 | </p></dd> | |
244 | <dt><span class="term">Throws:</span></dt> | |
245 | <dd><p> | |
246 | <code class="computeroutput"><span class="identifier">future_error</span></code> with | |
247 | <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">future_already_retrieved</span></code> or <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. | |
248 | </p></dd> | |
249 | </dl> | |
250 | </div> | |
251 | <p> | |
252 | </p> | |
253 | <h5> | |
254 | <a name="promise_set_value_bridgehead"></a> | |
255 | <span><a name="promise_set_value"></a></span> | |
256 | <a class="link" href="promise.html#promise_set_value">Member function | |
257 | <code class="computeroutput">set_value</code>()</a> | |
258 | </h5> | |
259 | <p> | |
260 | </p> | |
261 | <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">value</span><span class="special">);</span> <span class="comment">// member only of generic promise template</span> | |
262 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="special">&&</span> <span class="identifier">value</span><span class="special">);</span> <span class="comment">// member only of generic promise template</span> | |
263 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span> <span class="identifier">R</span> <span class="special">&</span> <span class="identifier">value</span><span class="special">);</span> <span class="comment">// member only of promise< R & > template</span> | |
264 | <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">();</span> <span class="comment">// member only of promise< void > template</span> | |
265 | </pre> | |
266 | <div class="variablelist"> | |
267 | <p class="title"><b></b></p> | |
268 | <dl> | |
269 | <dt><span class="term">Effects:</span></dt> | |
270 | <dd><p> | |
271 | Store the result in the <a class="link" href="future.html#shared_state">shared state</a> | |
272 | and marks the state as ready. | |
273 | </p></dd> | |
274 | <dt><span class="term">Throws:</span></dt> | |
275 | <dd><p> | |
276 | <code class="computeroutput"><span class="identifier">future_error</span></code> with | |
277 | <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">future_already_satisfied</span></code> or <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. | |
278 | </p></dd> | |
279 | </dl> | |
280 | </div> | |
281 | <p> | |
282 | </p> | |
283 | <h5> | |
284 | <a name="promise_set_exception_bridgehead"></a> | |
285 | <span><a name="promise_set_exception"></a></span> | |
286 | <a class="link" href="promise.html#promise_set_exception">Member | |
287 | function <code class="computeroutput">set_exception</code>()</a> | |
288 | </h5> | |
289 | <p> | |
290 | </p> | |
291 | <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span><span class="special">);</span> | |
292 | </pre> | |
293 | <div class="variablelist"> | |
294 | <p class="title"><b></b></p> | |
295 | <dl> | |
296 | <dt><span class="term">Effects:</span></dt> | |
297 | <dd><p> | |
298 | Store an exception pointer in the <a class="link" href="future.html#shared_state">shared | |
299 | state</a> and marks the state as ready. | |
300 | </p></dd> | |
301 | <dt><span class="term">Throws:</span></dt> | |
302 | <dd><p> | |
303 | <code class="computeroutput"><span class="identifier">future_error</span></code> with | |
304 | <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">future_already_satisfied</span></code> or <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">no_state</span></code>. | |
305 | </p></dd> | |
306 | </dl> | |
307 | </div> | |
308 | <p> | |
309 | </p> | |
310 | <h5> | |
311 | <a name="swap_for_promise_bridgehead"></a> | |
312 | <span><a name="swap_for_promise"></a></span> | |
313 | <a class="link" href="promise.html#swap_for_promise">Non-member function | |
314 | <code class="computeroutput">swap()</code></a> | |
315 | </h5> | |
316 | <p> | |
317 | </p> | |
318 | <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> | |
319 | <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <span class="identifier">promise</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">l</span><span class="special">,</span> <span class="identifier">promise</span><span class="special"><</span> <span class="identifier">R</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">r</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> | |
320 | </pre> | |
321 | <div class="variablelist"> | |
322 | <p class="title"><b></b></p> | |
323 | <dl> | |
324 | <dt><span class="term">Effects:</span></dt> | |
325 | <dd><p> | |
326 | Same as <code class="computeroutput"><span class="identifier">l</span><span class="special">.</span><span class="identifier">swap</span><span class="special">(</span> | |
327 | <span class="identifier">r</span><span class="special">)</span></code>. | |
328 | </p></dd> | |
329 | </dl> | |
330 | </div> | |
331 | </div> | |
332 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
333 | <td align="left"></td> | |
334 | <td align="right"><div class="copyright-footer">Copyright © 2013 Oliver Kowalke<p> | |
335 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
336 | file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) | |
337 | </p> | |
338 | </div></td> | |
339 | </tr></table> | |
340 | <hr> | |
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