1// Queue implementation -*- C++ -*-
2
3// Copyright (C) 2001-2024 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
24
25/*
26 *
27 * Copyright (c) 1994
28 * Hewlett-Packard Company
29 *
30 * Permission to use, copy, modify, distribute and sell this software
31 * and its documentation for any purpose is hereby granted without fee,
32 * provided that the above copyright notice appear in all copies and
33 * that both that copyright notice and this permission notice appear
34 * in supporting documentation. Hewlett-Packard Company makes no
35 * representations about the suitability of this software for any
36 * purpose. It is provided "as is" without express or implied warranty.
37 *
38 *
39 * Copyright (c) 1996,1997
40 * Silicon Graphics Computer Systems, Inc.
41 *
42 * Permission to use, copy, modify, distribute and sell this software
43 * and its documentation for any purpose is hereby granted without fee,
44 * provided that the above copyright notice appear in all copies and
45 * that both that copyright notice and this permission notice appear
46 * in supporting documentation. Silicon Graphics makes no
47 * representations about the suitability of this software for any
48 * purpose. It is provided "as is" without express or implied warranty.
49 */
50
51/** @file bits/stl_queue.h
52 * This is an internal header file, included by other library headers.
53 * Do not attempt to use it directly. @headername{queue}
54 */
55
56#ifndef _STL_QUEUE_H
57#define _STL_QUEUE_H 1
58
59#include <bits/concept_check.h>
60#include <debug/debug.h>
61#if __cplusplus >= 201103L
62# include <bits/uses_allocator.h>
63#endif
64
65namespace std _GLIBCXX_VISIBILITY(default)
66{
67_GLIBCXX_BEGIN_NAMESPACE_VERSION
68
69 /**
70 * @brief A standard container giving FIFO behavior.
71 *
72 * @ingroup sequences
73 *
74 * @tparam _Tp Type of element.
75 * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>.
76 *
77 * Meets many of the requirements of a
78 * <a href="tables.html#65">container</a>,
79 * but does not define anything to do with iterators. Very few of the
80 * other standard container interfaces are defined.
81 *
82 * This is not a true container, but an @e adaptor. It holds another
83 * container, and provides a wrapper interface to that container. The
84 * wrapper is what enforces strict first-in-first-out %queue behavior.
85 *
86 * The second template parameter defines the type of the underlying
87 * sequence/container. It defaults to std::deque, but it can be any type
88 * that supports @c front, @c back, @c push_back, and @c pop_front,
89 * such as std::list or an appropriate user-defined type.
90 *
91 * Members not found in @a normal containers are @c container_type,
92 * which is a typedef for the second Sequence parameter, and @c push and
93 * @c pop, which are standard %queue/FIFO operations.
94 */
95 template<typename _Tp, typename _Sequence = deque<_Tp> >
96 class queue
97 {
98#ifdef _GLIBCXX_CONCEPT_CHECKS
99 // concept requirements
100 typedef typename _Sequence::value_type _Sequence_value_type;
101# if __cplusplus < 201103L
102 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
103# endif
104 __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
105 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
106 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
107#endif
108
109 template<typename _Tp1, typename _Seq1>
110 friend bool
111 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
112
113 template<typename _Tp1, typename _Seq1>
114 friend bool
115 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
116
117#if __cpp_lib_three_way_comparison
118 template<typename _Tp1, three_way_comparable _Seq1>
119 friend compare_three_way_result_t<_Seq1>
120 operator<=>(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
121#endif
122
123#if __cplusplus >= 201103L
124 template<typename _Alloc>
125 using _Uses = typename
126 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
127
128#if __cplusplus >= 201703L
129 // _GLIBCXX_RESOLVE_LIB_DEFECTS
130 // 2566. Requirements on the first template parameter of container
131 // adaptors
132 static_assert(is_same<_Tp, typename _Sequence::value_type>::value,
133 "value_type must be the same as the underlying container");
134#endif // C++17
135#endif // C++11
136
137 public:
138 typedef typename _Sequence::value_type value_type;
139 typedef typename _Sequence::reference reference;
140 typedef typename _Sequence::const_reference const_reference;
141 typedef typename _Sequence::size_type size_type;
142 typedef _Sequence container_type;
143
144 protected:
145 /* Maintainers wondering why this isn't uglified as per style
146 * guidelines should note that this name is specified in the standard,
147 * C++98 [23.2.3.1].
148 * (Why? Presumably for the same reason that it's protected instead
149 * of private: to allow derivation. But none of the other
150 * containers allow for derivation. Odd.)
151 */
152 /// @c c is the underlying container.
153 _Sequence c;
154
155 public:
156 /**
157 * @brief Default constructor creates no elements.
158 */
159#if __cplusplus < 201103L
160 explicit
161 queue(const _Sequence& __c = _Sequence())
162 : c(__c) { }
163#else
164 template<typename _Seq = _Sequence, typename _Requires = typename
165 enable_if<is_default_constructible<_Seq>::value>::type>
166 queue()
167 : c() { }
168
169 explicit
170 queue(const _Sequence& __c)
171 : c(__c) { }
172
173 explicit
174 queue(_Sequence&& __c)
175 : c(std::move(__c)) { }
176
177 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
178 explicit
179 queue(const _Alloc& __a)
180 : c(__a) { }
181
182 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
183 queue(const _Sequence& __c, const _Alloc& __a)
184 : c(__c, __a) { }
185
186 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
187 queue(_Sequence&& __c, const _Alloc& __a)
188 : c(std::move(__c), __a) { }
189
190 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
191 queue(const queue& __q, const _Alloc& __a)
192 : c(__q.c, __a) { }
193
194 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
195 queue(queue&& __q, const _Alloc& __a)
196 : c(std::move(__q.c), __a) { }
197#endif
198
199#ifdef __glibcxx_adaptor_iterator_pair_constructor // C++ >= 23 && HOSTED
200 template<typename _InputIterator,
201 typename = _RequireInputIter<_InputIterator>>
202 queue(_InputIterator __first, _InputIterator __last)
203 : c(__first, __last) { }
204
205 template<typename _InputIterator, typename _Alloc,
206 typename = _RequireInputIter<_InputIterator>,
207 typename = _Uses<_Alloc>>
208 queue(_InputIterator __first, _InputIterator __last, const _Alloc& __a)
209 : c(__first, __last, __a) { }
210#endif
211
212 /**
213 * Returns true if the %queue is empty.
214 */
215 _GLIBCXX_NODISCARD bool
216 empty() const
217 { return c.empty(); }
218
219 /** Returns the number of elements in the %queue. */
220 _GLIBCXX_NODISCARD
221 size_type
222 size() const
223 { return c.size(); }
224
225 /**
226 * Returns a read/write reference to the data at the first
227 * element of the %queue.
228 */
229 _GLIBCXX_NODISCARD
230 reference
231 front()
232 {
233 __glibcxx_requires_nonempty();
234 return c.front();
235 }
236
237 /**
238 * Returns a read-only (constant) reference to the data at the first
239 * element of the %queue.
240 */
241 _GLIBCXX_NODISCARD
242 const_reference
243 front() const
244 {
245 __glibcxx_requires_nonempty();
246 return c.front();
247 }
248
249 /**
250 * Returns a read/write reference to the data at the last
251 * element of the %queue.
252 */
253 _GLIBCXX_NODISCARD
254 reference
255 back()
256 {
257 __glibcxx_requires_nonempty();
258 return c.back();
259 }
260
261 /**
262 * Returns a read-only (constant) reference to the data at the last
263 * element of the %queue.
264 */
265 _GLIBCXX_NODISCARD
266 const_reference
267 back() const
268 {
269 __glibcxx_requires_nonempty();
270 return c.back();
271 }
272
273 /**
274 * @brief Add data to the end of the %queue.
275 * @param __x Data to be added.
276 *
277 * This is a typical %queue operation. The function creates an
278 * element at the end of the %queue and assigns the given data
279 * to it. The time complexity of the operation depends on the
280 * underlying sequence.
281 */
282 void
283 push(const value_type& __x)
284 { c.push_back(__x); }
285
286#if __cplusplus >= 201103L
287 void
288 push(value_type&& __x)
289 { c.push_back(std::move(__x)); }
290
291#if __cplusplus > 201402L
292 template<typename... _Args>
293 decltype(auto)
294 emplace(_Args&&... __args)
295 { return c.emplace_back(std::forward<_Args>(__args)...); }
296#else
297 template<typename... _Args>
298 void
299 emplace(_Args&&... __args)
300 { c.emplace_back(std::forward<_Args>(__args)...); }
301#endif
302#endif
303
304 /**
305 * @brief Removes first element.
306 *
307 * This is a typical %queue operation. It shrinks the %queue by one.
308 * The time complexity of the operation depends on the underlying
309 * sequence.
310 *
311 * Note that no data is returned, and if the first element's
312 * data is needed, it should be retrieved before pop() is
313 * called.
314 */
315 void
316 pop()
317 {
318 __glibcxx_requires_nonempty();
319 c.pop_front();
320 }
321
322#if __cplusplus >= 201103L
323 void
324 swap(queue& __q)
325#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
326 noexcept(__is_nothrow_swappable<_Sequence>::value)
327#else
328 noexcept(__is_nothrow_swappable<_Tp>::value)
329#endif
330 {
331 using std::swap;
332 swap(c, __q.c);
333 }
334#endif // __cplusplus >= 201103L
335 };
336
337#if __cpp_deduction_guides >= 201606
338 template<typename _Container,
339 typename = _RequireNotAllocator<_Container>>
340 queue(_Container) -> queue<typename _Container::value_type, _Container>;
341
342 template<typename _Container, typename _Allocator,
343 typename = _RequireNotAllocator<_Container>>
344 queue(_Container, _Allocator)
345 -> queue<typename _Container::value_type, _Container>;
346
347#ifdef __glibcxx_adaptor_iterator_pair_constructor
348 template<typename _InputIterator,
349 typename _ValT
350 = typename iterator_traits<_InputIterator>::value_type,
351 typename = _RequireInputIter<_InputIterator>>
352 queue(_InputIterator, _InputIterator) -> queue<_ValT>;
353
354 template<typename _InputIterator, typename _Allocator,
355 typename _ValT
356 = typename iterator_traits<_InputIterator>::value_type,
357 typename = _RequireInputIter<_InputIterator>,
358 typename = _RequireAllocator<_Allocator>>
359 queue(_InputIterator, _InputIterator, _Allocator)
360 -> queue<_ValT, deque<_ValT, _Allocator>>;
361#endif
362#endif
363
364 /**
365 * @brief Queue equality comparison.
366 * @param __x A %queue.
367 * @param __y A %queue of the same type as @a __x.
368 * @return True iff the size and elements of the queues are equal.
369 *
370 * This is an equivalence relation. Complexity and semantics depend on the
371 * underlying sequence type, but the expected rules are: this relation is
372 * linear in the size of the sequences, and queues are considered equivalent
373 * if their sequences compare equal.
374 */
375 template<typename _Tp, typename _Seq>
376 _GLIBCXX_NODISCARD
377 inline bool
378 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
379 { return __x.c == __y.c; }
380
381 /**
382 * @brief Queue ordering relation.
383 * @param __x A %queue.
384 * @param __y A %queue of the same type as @a x.
385 * @return True iff @a __x is lexicographically less than @a __y.
386 *
387 * This is an total ordering relation. Complexity and semantics
388 * depend on the underlying sequence type, but the expected rules
389 * are: this relation is linear in the size of the sequences, the
390 * elements must be comparable with @c <, and
391 * std::lexicographical_compare() is usually used to make the
392 * determination.
393 */
394 template<typename _Tp, typename _Seq>
395 _GLIBCXX_NODISCARD
396 inline bool
397 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
398 { return __x.c < __y.c; }
399
400 /// Based on operator==
401 template<typename _Tp, typename _Seq>
402 _GLIBCXX_NODISCARD
403 inline bool
404 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
405 { return !(__x == __y); }
406
407 /// Based on operator<
408 template<typename _Tp, typename _Seq>
409 _GLIBCXX_NODISCARD
410 inline bool
411 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
412 { return __y < __x; }
413
414 /// Based on operator<
415 template<typename _Tp, typename _Seq>
416 _GLIBCXX_NODISCARD
417 inline bool
418 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
419 { return !(__y < __x); }
420
421 /// Based on operator<
422 template<typename _Tp, typename _Seq>
423 _GLIBCXX_NODISCARD
424 inline bool
425 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
426 { return !(__x < __y); }
427
428#if __cpp_lib_three_way_comparison
429 template<typename _Tp, three_way_comparable _Seq>
430 [[nodiscard]]
431 inline compare_three_way_result_t<_Seq>
432 operator<=>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
433 { return __x.c <=> __y.c; }
434#endif
435
436#if __cplusplus >= 201103L
437 template<typename _Tp, typename _Seq>
438 inline
439#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
440 // Constrained free swap overload, see p0185r1
441 typename enable_if<__is_swappable<_Seq>::value>::type
442#else
443 void
444#endif
445 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
446 noexcept(noexcept(__x.swap(__y)))
447 { __x.swap(__y); }
448
449 template<typename _Tp, typename _Seq, typename _Alloc>
450 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
451 : public uses_allocator<_Seq, _Alloc>::type { };
452#endif // __cplusplus >= 201103L
453
454 /**
455 * @brief A standard container automatically sorting its contents.
456 *
457 * @ingroup sequences
458 *
459 * @tparam _Tp Type of element.
460 * @tparam _Sequence Type of underlying sequence, defaults to vector<_Tp>.
461 * @tparam _Compare Comparison function object type, defaults to
462 * less<_Sequence::value_type>.
463 *
464 * This is not a true container, but an @e adaptor. It holds
465 * another container, and provides a wrapper interface to that
466 * container. The wrapper is what enforces priority-based sorting
467 * and %queue behavior. Very few of the standard container/sequence
468 * interface requirements are met (e.g., iterators).
469 *
470 * The second template parameter defines the type of the underlying
471 * sequence/container. It defaults to std::vector, but it can be
472 * any type that supports @c front(), @c push_back, @c pop_back,
473 * and random-access iterators, such as std::deque or an
474 * appropriate user-defined type.
475 *
476 * The third template parameter supplies the means of making
477 * priority comparisons. It defaults to @c less<value_type> but
478 * can be anything defining a strict weak ordering.
479 *
480 * Members not found in @a normal containers are @c container_type,
481 * which is a typedef for the second Sequence parameter, and @c
482 * push, @c pop, and @c top, which are standard %queue operations.
483 *
484 * @note No equality/comparison operators are provided for
485 * %priority_queue.
486 *
487 * @note Sorting of the elements takes place as they are added to,
488 * and removed from, the %priority_queue using the
489 * %priority_queue's member functions. If you access the elements
490 * by other means, and change their data such that the sorting
491 * order would be different, the %priority_queue will not re-sort
492 * the elements for you. (How could it know to do so?)
493 */
494 template<typename _Tp, typename _Sequence = vector<_Tp>,
495 typename _Compare = less<typename _Sequence::value_type> >
496 class priority_queue
497 {
498#ifdef _GLIBCXX_CONCEPT_CHECKS
499 // concept requirements
500 typedef typename _Sequence::value_type _Sequence_value_type;
501# if __cplusplus < 201103L
502 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
503# endif
504 __glibcxx_class_requires(_Sequence, _SequenceConcept)
505 __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
506 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
507 __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
508 _BinaryFunctionConcept)
509#endif
510
511#if __cplusplus >= 201103L
512 template<typename _Alloc>
513 using _Uses = typename
514 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
515
516#if __cplusplus >= 201703L
517 // _GLIBCXX_RESOLVE_LIB_DEFECTS
518 // 2566. Requirements on the first template parameter of container
519 // adaptors
520 static_assert(is_same<_Tp, typename _Sequence::value_type>::value,
521 "value_type must be the same as the underlying container");
522#endif // C++17
523#endif // C++11
524
525 public:
526 typedef typename _Sequence::value_type value_type;
527 typedef typename _Sequence::reference reference;
528 typedef typename _Sequence::const_reference const_reference;
529 typedef typename _Sequence::size_type size_type;
530 typedef _Sequence container_type;
531 // _GLIBCXX_RESOLVE_LIB_DEFECTS
532 // DR 2684. priority_queue lacking comparator typedef
533 typedef _Compare value_compare;
534
535 protected:
536 // See queue::c for notes on these names.
537 _Sequence c;
538 _Compare comp;
539
540 public:
541 /**
542 * @brief Default constructor creates no elements.
543 */
544#if __cplusplus < 201103L
545 explicit
546 priority_queue(const _Compare& __x = _Compare(),
547 const _Sequence& __s = _Sequence())
548 : c(__s), comp(__x)
549 { std::make_heap(c.begin(), c.end(), comp); }
550#else
551 template<typename _Seq = _Sequence, typename _Requires = typename
552 enable_if<__and_<is_default_constructible<_Compare>,
553 is_default_constructible<_Seq>>::value>::type>
554 priority_queue()
555 : c(), comp() { }
556
557 explicit
558 priority_queue(const _Compare& __x, const _Sequence& __s)
559 : c(__s), comp(__x)
560 { std::make_heap(c.begin(), c.end(), comp); }
561
562 explicit
563 priority_queue(const _Compare& __x, _Sequence&& __s = _Sequence())
564 : c(std::move(__s)), comp(__x)
565 { std::make_heap(c.begin(), c.end(), comp); }
566
567 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
568 explicit
569 priority_queue(const _Alloc& __a)
570 : c(__a), comp() { }
571
572 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
573 priority_queue(const _Compare& __x, const _Alloc& __a)
574 : c(__a), comp(__x) { }
575
576 // _GLIBCXX_RESOLVE_LIB_DEFECTS
577 // 2537. Constructors [...] taking allocators should call make_heap
578 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
579 priority_queue(const _Compare& __x, const _Sequence& __c,
580 const _Alloc& __a)
581 : c(__c, __a), comp(__x)
582 { std::make_heap(c.begin(), c.end(), comp); }
583
584 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
585 priority_queue(const _Compare& __x, _Sequence&& __c, const _Alloc& __a)
586 : c(std::move(__c), __a), comp(__x)
587 { std::make_heap(c.begin(), c.end(), comp); }
588
589 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
590 priority_queue(const priority_queue& __q, const _Alloc& __a)
591 : c(__q.c, __a), comp(__q.comp) { }
592
593 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
594 priority_queue(priority_queue&& __q, const _Alloc& __a)
595 : c(std::move(__q.c), __a), comp(std::move(__q.comp)) { }
596#endif
597
598 /**
599 * @brief Builds a %queue from a range.
600 * @param __first An input iterator.
601 * @param __last An input iterator.
602 * @param __x A comparison functor describing a strict weak ordering.
603 * @param __s An initial sequence with which to start.
604 *
605 * Begins by copying @a __s, inserting a copy of the elements
606 * from @a [first,last) into the copy of @a __s, then ordering
607 * the copy according to @a __x.
608 *
609 * For more information on function objects, see the
610 * documentation on @link functors functor base
611 * classes@endlink.
612 */
613#if __cplusplus < 201103L
614 template<typename _InputIterator>
615 priority_queue(_InputIterator __first, _InputIterator __last,
616 const _Compare& __x = _Compare(),
617 const _Sequence& __s = _Sequence())
618 : c(__s), comp(__x)
619 {
620 __glibcxx_requires_valid_range(__first, __last);
621 c.insert(c.end(), __first, __last);
622 std::make_heap(c.begin(), c.end(), comp);
623 }
624#else
625 // _GLIBCXX_RESOLVE_LIB_DEFECTS
626 // 3529. priority_queue(first, last) should construct c with (first, last)
627 template<typename _InputIterator,
628 typename = std::_RequireInputIter<_InputIterator>>
629 priority_queue(_InputIterator __first, _InputIterator __last,
630 const _Compare& __x = _Compare())
631 : c(__first, __last), comp(__x)
632 { std::make_heap(c.begin(), c.end(), comp); }
633
634 // _GLIBCXX_RESOLVE_LIB_DEFECTS
635 // 3522. Missing requirement on InputIterator template parameter
636 template<typename _InputIterator,
637 typename = std::_RequireInputIter<_InputIterator>>
638 priority_queue(_InputIterator __first, _InputIterator __last,
639 const _Compare& __x, const _Sequence& __s)
640 : c(__s), comp(__x)
641 {
642 __glibcxx_requires_valid_range(__first, __last);
643 c.insert(c.end(), __first, __last);
644 std::make_heap(c.begin(), c.end(), comp);
645 }
646
647 template<typename _InputIterator,
648 typename = std::_RequireInputIter<_InputIterator>>
649 priority_queue(_InputIterator __first, _InputIterator __last,
650 const _Compare& __x, _Sequence&& __s)
651 : c(std::move(__s)), comp(__x)
652 {
653 __glibcxx_requires_valid_range(__first, __last);
654 c.insert(c.end(), __first, __last);
655 std::make_heap(c.begin(), c.end(), comp);
656 }
657
658 // _GLIBCXX_RESOLVE_LIB_DEFECTS
659 // 3506. Missing allocator-extended constructors for priority_queue
660 template<typename _InputIterator, typename _Alloc,
661 typename = std::_RequireInputIter<_InputIterator>,
662 typename _Requires = _Uses<_Alloc>>
663 priority_queue(_InputIterator __first, _InputIterator __last,
664 const _Alloc& __alloc)
665 : c(__first, __last, __alloc), comp()
666 { std::make_heap(c.begin(), c.end(), comp); }
667
668 template<typename _InputIterator, typename _Alloc,
669 typename = std::_RequireInputIter<_InputIterator>,
670 typename _Requires = _Uses<_Alloc>>
671 priority_queue(_InputIterator __first, _InputIterator __last,
672 const _Compare& __x, const _Alloc& __alloc)
673 : c(__first, __last, __alloc), comp(__x)
674 { std::make_heap(c.begin(), c.end(), comp); }
675
676 template<typename _InputIterator, typename _Alloc,
677 typename = std::_RequireInputIter<_InputIterator>,
678 typename _Requires = _Uses<_Alloc>>
679 priority_queue(_InputIterator __first, _InputIterator __last,
680 const _Compare& __x, const _Sequence& __s,
681 const _Alloc& __alloc)
682 : c(__s, __alloc), comp(__x)
683 {
684 __glibcxx_requires_valid_range(__first, __last);
685 c.insert(c.end(), __first, __last);
686 std::make_heap(c.begin(), c.end(), comp);
687 }
688
689 template<typename _InputIterator, typename _Alloc,
690 typename _Requires = _Uses<_Alloc>>
691 priority_queue(_InputIterator __first, _InputIterator __last,
692 const _Compare& __x, _Sequence&& __s,
693 const _Alloc& __alloc)
694 : c(std::move(__s), __alloc), comp(__x)
695 {
696 __glibcxx_requires_valid_range(__first, __last);
697 c.insert(c.end(), __first, __last);
698 std::make_heap(c.begin(), c.end(), comp);
699 }
700#endif
701
702 /**
703 * Returns true if the %queue is empty.
704 */
705 _GLIBCXX_NODISCARD bool
706 empty() const
707 { return c.empty(); }
708
709 /** Returns the number of elements in the %queue. */
710 _GLIBCXX_NODISCARD
711 size_type
712 size() const
713 { return c.size(); }
714
715 /**
716 * Returns a read-only (constant) reference to the data at the first
717 * element of the %queue.
718 */
719 _GLIBCXX_NODISCARD
720 const_reference
721 top() const
722 {
723 __glibcxx_requires_nonempty();
724 return c.front();
725 }
726
727 /**
728 * @brief Add data to the %queue.
729 * @param __x Data to be added.
730 *
731 * This is a typical %queue operation.
732 * The time complexity of the operation depends on the underlying
733 * sequence.
734 */
735 void
736 push(const value_type& __x)
737 {
738 c.push_back(__x);
739 std::push_heap(c.begin(), c.end(), comp);
740 }
741
742#if __cplusplus >= 201103L
743 void
744 push(value_type&& __x)
745 {
746 c.push_back(std::move(__x));
747 std::push_heap(c.begin(), c.end(), comp);
748 }
749
750 template<typename... _Args>
751 void
752 emplace(_Args&&... __args)
753 {
754 c.emplace_back(std::forward<_Args>(__args)...);
755 std::push_heap(c.begin(), c.end(), comp);
756 }
757#endif
758
759 /**
760 * @brief Removes first element.
761 *
762 * This is a typical %queue operation. It shrinks the %queue
763 * by one. The time complexity of the operation depends on the
764 * underlying sequence.
765 *
766 * Note that no data is returned, and if the first element's
767 * data is needed, it should be retrieved before pop() is
768 * called.
769 */
770 void
771 pop()
772 {
773 __glibcxx_requires_nonempty();
774 std::pop_heap(c.begin(), c.end(), comp);
775 c.pop_back();
776 }
777
778#if __cplusplus >= 201103L
779 void
780 swap(priority_queue& __pq)
781 noexcept(__and_<
782#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
783 __is_nothrow_swappable<_Sequence>,
784#else
785 __is_nothrow_swappable<_Tp>,
786#endif
787 __is_nothrow_swappable<_Compare>
788 >::value)
789 {
790 using std::swap;
791 swap(c, __pq.c);
792 swap(comp, __pq.comp);
793 }
794#endif // __cplusplus >= 201103L
795 };
796
797#if __cpp_deduction_guides >= 201606
798 template<typename _Compare, typename _Container,
799 typename = _RequireNotAllocator<_Compare>,
800 typename = _RequireNotAllocator<_Container>>
801 priority_queue(_Compare, _Container)
802 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
803
804 template<typename _InputIterator, typename _ValT
805 = typename iterator_traits<_InputIterator>::value_type,
806 typename _Compare = less<_ValT>,
807 typename _Container = vector<_ValT>,
808 typename = _RequireInputIter<_InputIterator>,
809 typename = _RequireNotAllocator<_Compare>,
810 typename = _RequireNotAllocator<_Container>>
811 priority_queue(_InputIterator, _InputIterator, _Compare = _Compare(),
812 _Container = _Container())
813 -> priority_queue<_ValT, _Container, _Compare>;
814
815 template<typename _Compare, typename _Container, typename _Allocator,
816 typename = _RequireNotAllocator<_Compare>,
817 typename = _RequireNotAllocator<_Container>>
818 priority_queue(_Compare, _Container, _Allocator)
819 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
820#endif
821
822 // No equality/comparison operators are provided for priority_queue.
823
824#if __cplusplus >= 201103L
825 template<typename _Tp, typename _Sequence, typename _Compare>
826 inline
827#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
828 // Constrained free swap overload, see p0185r1
829 typename enable_if<__and_<__is_swappable<_Sequence>,
830 __is_swappable<_Compare>>::value>::type
831#else
832 void
833#endif
834 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
835 priority_queue<_Tp, _Sequence, _Compare>& __y)
836 noexcept(noexcept(__x.swap(__y)))
837 { __x.swap(__y); }
838
839 template<typename _Tp, typename _Sequence, typename _Compare,
840 typename _Alloc>
841 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
842 : public uses_allocator<_Sequence, _Alloc>::type { };
843#endif // __cplusplus >= 201103L
844
845_GLIBCXX_END_NAMESPACE_VERSION
846} // namespace
847
848#endif /* _STL_QUEUE_H */
849