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[gcc.git] / libstdc++-v3 / include / bits / stl_queue.h
1 // Queue implementation -*- C++ -*-
2
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 // 2010, 2011
5 // Free Software Foundation, Inc.
6 //
7 // This file is part of the GNU ISO C++ Library. This library is free
8 // software; you can redistribute it and/or modify it under the
9 // terms of the GNU General Public License as published by the
10 // Free Software Foundation; either version 3, or (at your option)
11 // any later version.
12
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17
18 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
21
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
26
27 /*
28 *
29 * Copyright (c) 1994
30 * Hewlett-Packard Company
31 *
32 * Permission to use, copy, modify, distribute and sell this software
33 * and its documentation for any purpose is hereby granted without fee,
34 * provided that the above copyright notice appear in all copies and
35 * that both that copyright notice and this permission notice appear
36 * in supporting documentation. Hewlett-Packard Company makes no
37 * representations about the suitability of this software for any
38 * purpose. It is provided "as is" without express or implied warranty.
39 *
40 *
41 * Copyright (c) 1996,1997
42 * Silicon Graphics Computer Systems, Inc.
43 *
44 * Permission to use, copy, modify, distribute and sell this software
45 * and its documentation for any purpose is hereby granted without fee,
46 * provided that the above copyright notice appear in all copies and
47 * that both that copyright notice and this permission notice appear
48 * in supporting documentation. Silicon Graphics makes no
49 * representations about the suitability of this software for any
50 * purpose. It is provided "as is" without express or implied warranty.
51 */
52
53 /** @file bits/stl_queue.h
54 * This is an internal header file, included by other library headers.
55 * Do not attempt to use it directly. @headername{queue}
56 */
57
58 #ifndef _STL_QUEUE_H
59 #define _STL_QUEUE_H 1
60
61 #include <bits/concept_check.h>
62 #include <debug/debug.h>
63
64 namespace std _GLIBCXX_VISIBILITY(default)
65 {
66 _GLIBCXX_BEGIN_NAMESPACE_VERSION
67
68 /**
69 * @brief A standard container giving FIFO behavior.
70 *
71 * @ingroup sequences
72 *
73 * Meets many of the requirements of a
74 * <a href="tables.html#65">container</a>,
75 * but does not define anything to do with iterators. Very few of the
76 * other standard container interfaces are defined.
77 *
78 * This is not a true container, but an @e adaptor. It holds another
79 * container, and provides a wrapper interface to that container. The
80 * wrapper is what enforces strict first-in-first-out %queue behavior.
81 *
82 * The second template parameter defines the type of the underlying
83 * sequence/container. It defaults to std::deque, but it can be any type
84 * that supports @c front, @c back, @c push_back, and @c pop_front,
85 * such as std::list or an appropriate user-defined type.
86 *
87 * Members not found in @a normal containers are @c container_type,
88 * which is a typedef for the second Sequence parameter, and @c push and
89 * @c pop, which are standard %queue/FIFO operations.
90 */
91 template<typename _Tp, typename _Sequence = deque<_Tp> >
92 class queue
93 {
94 // concept requirements
95 typedef typename _Sequence::value_type _Sequence_value_type;
96 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
97 __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
98 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
99 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
100
101 template<typename _Tp1, typename _Seq1>
102 friend bool
103 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
104
105 template<typename _Tp1, typename _Seq1>
106 friend bool
107 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
108
109 public:
110 typedef typename _Sequence::value_type value_type;
111 typedef typename _Sequence::reference reference;
112 typedef typename _Sequence::const_reference const_reference;
113 typedef typename _Sequence::size_type size_type;
114 typedef _Sequence container_type;
115
116 protected:
117 /**
118 * 'c' is the underlying container. Maintainers wondering why
119 * this isn't uglified as per style guidelines should note that
120 * this name is specified in the standard, [23.2.3.1]. (Why?
121 * Presumably for the same reason that it's protected instead
122 * of private: to allow derivation. But none of the other
123 * containers allow for derivation. Odd.)
124 */
125 _Sequence c;
126
127 public:
128 /**
129 * @brief Default constructor creates no elements.
130 */
131 #ifndef __GXX_EXPERIMENTAL_CXX0X__
132 explicit
133 queue(const _Sequence& __c = _Sequence())
134 : c(__c) { }
135 #else
136 explicit
137 queue(const _Sequence& __c)
138 : c(__c) { }
139
140 explicit
141 queue(_Sequence&& __c = _Sequence())
142 : c(std::move(__c)) { }
143 #endif
144
145 /**
146 * Returns true if the %queue is empty.
147 */
148 bool
149 empty() const
150 { return c.empty(); }
151
152 /** Returns the number of elements in the %queue. */
153 size_type
154 size() const
155 { return c.size(); }
156
157 /**
158 * Returns a read/write reference to the data at the first
159 * element of the %queue.
160 */
161 reference
162 front()
163 {
164 __glibcxx_requires_nonempty();
165 return c.front();
166 }
167
168 /**
169 * Returns a read-only (constant) reference to the data at the first
170 * element of the %queue.
171 */
172 const_reference
173 front() const
174 {
175 __glibcxx_requires_nonempty();
176 return c.front();
177 }
178
179 /**
180 * Returns a read/write reference to the data at the last
181 * element of the %queue.
182 */
183 reference
184 back()
185 {
186 __glibcxx_requires_nonempty();
187 return c.back();
188 }
189
190 /**
191 * Returns a read-only (constant) reference to the data at the last
192 * element of the %queue.
193 */
194 const_reference
195 back() const
196 {
197 __glibcxx_requires_nonempty();
198 return c.back();
199 }
200
201 /**
202 * @brief Add data to the end of the %queue.
203 * @param x Data to be added.
204 *
205 * This is a typical %queue operation. The function creates an
206 * element at the end of the %queue and assigns the given data
207 * to it. The time complexity of the operation depends on the
208 * underlying sequence.
209 */
210 void
211 push(const value_type& __x)
212 { c.push_back(__x); }
213
214 #ifdef __GXX_EXPERIMENTAL_CXX0X__
215 void
216 push(value_type&& __x)
217 { c.push_back(std::move(__x)); }
218
219 template<typename... _Args>
220 void
221 emplace(_Args&&... __args)
222 { c.emplace_back(std::forward<_Args>(__args)...); }
223 #endif
224
225 /**
226 * @brief Removes first element.
227 *
228 * This is a typical %queue operation. It shrinks the %queue by one.
229 * The time complexity of the operation depends on the underlying
230 * sequence.
231 *
232 * Note that no data is returned, and if the first element's
233 * data is needed, it should be retrieved before pop() is
234 * called.
235 */
236 void
237 pop()
238 {
239 __glibcxx_requires_nonempty();
240 c.pop_front();
241 }
242
243 #ifdef __GXX_EXPERIMENTAL_CXX0X__
244 void
245 swap(queue& __q)
246 noexcept(noexcept(swap(c, __q.c)))
247 {
248 using std::swap;
249 swap(c, __q.c);
250 }
251 #endif
252 };
253
254 /**
255 * @brief Queue equality comparison.
256 * @param x A %queue.
257 * @param y A %queue of the same type as @a x.
258 * @return True iff the size and elements of the queues are equal.
259 *
260 * This is an equivalence relation. Complexity and semantics depend on the
261 * underlying sequence type, but the expected rules are: this relation is
262 * linear in the size of the sequences, and queues are considered equivalent
263 * if their sequences compare equal.
264 */
265 template<typename _Tp, typename _Seq>
266 inline bool
267 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
268 { return __x.c == __y.c; }
269
270 /**
271 * @brief Queue ordering relation.
272 * @param x A %queue.
273 * @param y A %queue of the same type as @a x.
274 * @return True iff @a x is lexicographically less than @a y.
275 *
276 * This is an total ordering relation. Complexity and semantics
277 * depend on the underlying sequence type, but the expected rules
278 * are: this relation is linear in the size of the sequences, the
279 * elements must be comparable with @c <, and
280 * std::lexicographical_compare() is usually used to make the
281 * determination.
282 */
283 template<typename _Tp, typename _Seq>
284 inline bool
285 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
286 { return __x.c < __y.c; }
287
288 /// Based on operator==
289 template<typename _Tp, typename _Seq>
290 inline bool
291 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
292 { return !(__x == __y); }
293
294 /// Based on operator<
295 template<typename _Tp, typename _Seq>
296 inline bool
297 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
298 { return __y < __x; }
299
300 /// Based on operator<
301 template<typename _Tp, typename _Seq>
302 inline bool
303 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
304 { return !(__y < __x); }
305
306 /// Based on operator<
307 template<typename _Tp, typename _Seq>
308 inline bool
309 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
310 { return !(__x < __y); }
311
312 #ifdef __GXX_EXPERIMENTAL_CXX0X__
313 template<typename _Tp, typename _Seq>
314 inline void
315 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
316 noexcept(noexcept(__x.swap(__y)))
317 { __x.swap(__y); }
318
319 template<typename _Tp, typename _Seq, typename _Alloc>
320 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
321 : public uses_allocator<_Seq, _Alloc>::type { };
322 #endif
323
324 /**
325 * @brief A standard container automatically sorting its contents.
326 *
327 * @ingroup sequences
328 *
329 * This is not a true container, but an @e adaptor. It holds
330 * another container, and provides a wrapper interface to that
331 * container. The wrapper is what enforces priority-based sorting
332 * and %queue behavior. Very few of the standard container/sequence
333 * interface requirements are met (e.g., iterators).
334 *
335 * The second template parameter defines the type of the underlying
336 * sequence/container. It defaults to std::vector, but it can be
337 * any type that supports @c front(), @c push_back, @c pop_back,
338 * and random-access iterators, such as std::deque or an
339 * appropriate user-defined type.
340 *
341 * The third template parameter supplies the means of making
342 * priority comparisons. It defaults to @c less<value_type> but
343 * can be anything defining a strict weak ordering.
344 *
345 * Members not found in @a normal containers are @c container_type,
346 * which is a typedef for the second Sequence parameter, and @c
347 * push, @c pop, and @c top, which are standard %queue operations.
348 *
349 * @note No equality/comparison operators are provided for
350 * %priority_queue.
351 *
352 * @note Sorting of the elements takes place as they are added to,
353 * and removed from, the %priority_queue using the
354 * %priority_queue's member functions. If you access the elements
355 * by other means, and change their data such that the sorting
356 * order would be different, the %priority_queue will not re-sort
357 * the elements for you. (How could it know to do so?)
358 */
359 template<typename _Tp, typename _Sequence = vector<_Tp>,
360 typename _Compare = less<typename _Sequence::value_type> >
361 class priority_queue
362 {
363 // concept requirements
364 typedef typename _Sequence::value_type _Sequence_value_type;
365 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
366 __glibcxx_class_requires(_Sequence, _SequenceConcept)
367 __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
368 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
369 __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
370 _BinaryFunctionConcept)
371
372 public:
373 typedef typename _Sequence::value_type value_type;
374 typedef typename _Sequence::reference reference;
375 typedef typename _Sequence::const_reference const_reference;
376 typedef typename _Sequence::size_type size_type;
377 typedef _Sequence container_type;
378
379 protected:
380 // See queue::c for notes on these names.
381 _Sequence c;
382 _Compare comp;
383
384 public:
385 /**
386 * @brief Default constructor creates no elements.
387 */
388 #ifndef __GXX_EXPERIMENTAL_CXX0X__
389 explicit
390 priority_queue(const _Compare& __x = _Compare(),
391 const _Sequence& __s = _Sequence())
392 : c(__s), comp(__x)
393 { std::make_heap(c.begin(), c.end(), comp); }
394 #else
395 explicit
396 priority_queue(const _Compare& __x,
397 const _Sequence& __s)
398 : c(__s), comp(__x)
399 { std::make_heap(c.begin(), c.end(), comp); }
400
401 explicit
402 priority_queue(const _Compare& __x = _Compare(),
403 _Sequence&& __s = _Sequence())
404 : c(std::move(__s)), comp(__x)
405 { std::make_heap(c.begin(), c.end(), comp); }
406 #endif
407
408 /**
409 * @brief Builds a %queue from a range.
410 * @param first An input iterator.
411 * @param last An input iterator.
412 * @param x A comparison functor describing a strict weak ordering.
413 * @param s An initial sequence with which to start.
414 *
415 * Begins by copying @a s, inserting a copy of the elements
416 * from @a [first,last) into the copy of @a s, then ordering
417 * the copy according to @a x.
418 *
419 * For more information on function objects, see the
420 * documentation on @link functors functor base
421 * classes@endlink.
422 */
423 #ifndef __GXX_EXPERIMENTAL_CXX0X__
424 template<typename _InputIterator>
425 priority_queue(_InputIterator __first, _InputIterator __last,
426 const _Compare& __x = _Compare(),
427 const _Sequence& __s = _Sequence())
428 : c(__s), comp(__x)
429 {
430 __glibcxx_requires_valid_range(__first, __last);
431 c.insert(c.end(), __first, __last);
432 std::make_heap(c.begin(), c.end(), comp);
433 }
434 #else
435 template<typename _InputIterator>
436 priority_queue(_InputIterator __first, _InputIterator __last,
437 const _Compare& __x,
438 const _Sequence& __s)
439 : c(__s), comp(__x)
440 {
441 __glibcxx_requires_valid_range(__first, __last);
442 c.insert(c.end(), __first, __last);
443 std::make_heap(c.begin(), c.end(), comp);
444 }
445
446 template<typename _InputIterator>
447 priority_queue(_InputIterator __first, _InputIterator __last,
448 const _Compare& __x = _Compare(),
449 _Sequence&& __s = _Sequence())
450 : c(std::move(__s)), comp(__x)
451 {
452 __glibcxx_requires_valid_range(__first, __last);
453 c.insert(c.end(), __first, __last);
454 std::make_heap(c.begin(), c.end(), comp);
455 }
456 #endif
457
458 /**
459 * Returns true if the %queue is empty.
460 */
461 bool
462 empty() const
463 { return c.empty(); }
464
465 /** Returns the number of elements in the %queue. */
466 size_type
467 size() const
468 { return c.size(); }
469
470 /**
471 * Returns a read-only (constant) reference to the data at the first
472 * element of the %queue.
473 */
474 const_reference
475 top() const
476 {
477 __glibcxx_requires_nonempty();
478 return c.front();
479 }
480
481 /**
482 * @brief Add data to the %queue.
483 * @param x Data to be added.
484 *
485 * This is a typical %queue operation.
486 * The time complexity of the operation depends on the underlying
487 * sequence.
488 */
489 void
490 push(const value_type& __x)
491 {
492 c.push_back(__x);
493 std::push_heap(c.begin(), c.end(), comp);
494 }
495
496 #ifdef __GXX_EXPERIMENTAL_CXX0X__
497 void
498 push(value_type&& __x)
499 {
500 c.push_back(std::move(__x));
501 std::push_heap(c.begin(), c.end(), comp);
502 }
503
504 template<typename... _Args>
505 void
506 emplace(_Args&&... __args)
507 {
508 c.emplace_back(std::forward<_Args>(__args)...);
509 std::push_heap(c.begin(), c.end(), comp);
510 }
511 #endif
512
513 /**
514 * @brief Removes first element.
515 *
516 * This is a typical %queue operation. It shrinks the %queue
517 * by one. The time complexity of the operation depends on the
518 * underlying sequence.
519 *
520 * Note that no data is returned, and if the first element's
521 * data is needed, it should be retrieved before pop() is
522 * called.
523 */
524 void
525 pop()
526 {
527 __glibcxx_requires_nonempty();
528 std::pop_heap(c.begin(), c.end(), comp);
529 c.pop_back();
530 }
531
532 #ifdef __GXX_EXPERIMENTAL_CXX0X__
533 void
534 swap(priority_queue& __pq)
535 noexcept(noexcept(swap(c, __pq.c)) && noexcept(swap(comp, __pq.comp)))
536 {
537 using std::swap;
538 swap(c, __pq.c);
539 swap(comp, __pq.comp);
540 }
541 #endif
542 };
543
544 // No equality/comparison operators are provided for priority_queue.
545
546 #ifdef __GXX_EXPERIMENTAL_CXX0X__
547 template<typename _Tp, typename _Sequence, typename _Compare>
548 inline void
549 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
550 priority_queue<_Tp, _Sequence, _Compare>& __y)
551 noexcept(noexcept(__x.swap(__y)))
552 { __x.swap(__y); }
553
554 template<typename _Tp, typename _Sequence, typename _Compare,
555 typename _Alloc>
556 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
557 : public uses_allocator<_Sequence, _Alloc>::type { };
558 #endif
559
560 _GLIBCXX_END_NAMESPACE_VERSION
561 } // namespace
562
563 #endif /* _STL_QUEUE_H */