libstdc++: stl_queue.h Source File

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stl_queue.h
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1// Queue implementation -*- C++ -*-
2
3// Copyright (C) 2001-2026 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#if __glibcxx_containers_ranges // C++ >= 23
65# include <ranges> // ranges::to
66# include <bits/ranges_algobase.h> // ranges::copy
67#endif
68
69namespace std _GLIBCXX_VISIBILITY(default)
70{
71_GLIBCXX_BEGIN_NAMESPACE_VERSION
72
73#if __glibcxx_format_ranges
74 template<typename, typename> class formatter;
75#endif
76
77 /**
78 * @brief A standard container giving FIFO behavior.
79 *
80 * @ingroup sequences
81 *
82 * @tparam _Tp Type of element.
83 * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>.
84 *
85 * Meets many of the requirements of a
86 * <a href="tables.html#65">container</a>,
87 * but does not define anything to do with iterators. Very few of the
88 * other standard container interfaces are defined.
89 *
90 * This is not a true container, but an @e adaptor. It holds another
91 * container, and provides a wrapper interface to that container. The
92 * wrapper is what enforces strict first-in-first-out %queue behavior.
93 *
94 * The second template parameter defines the type of the underlying
95 * sequence/container. It defaults to std::deque, but it can be any type
96 * that supports @c front, @c back, @c push_back, and @c pop_front,
97 * such as std::list or an appropriate user-defined type.
98 *
99 * Members not found in @a normal containers are @c container_type,
100 * which is a typedef for the second Sequence parameter, and @c push and
101 * @c pop, which are standard %queue/FIFO operations.
102 */
103 template<typename _Tp, typename _Sequence = deque<_Tp> >
104 class queue
105 {
106#ifdef _GLIBCXX_CONCEPT_CHECKS
107 // concept requirements
108 typedef typename _Sequence::value_type _Sequence_value_type;
109# if __cplusplus < 201103L
110 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
111# endif
112 __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
113 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
114 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
115#endif
116
117 template<typename _Tp1, typename _Seq1>
118 friend bool
119 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
120
121 template<typename _Tp1, typename _Seq1>
122 friend bool
123 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
124
125#if __cpp_lib_three_way_comparison
126 template<typename _Tp1, three_way_comparable _Seq1>
127 friend compare_three_way_result_t<_Seq1>
128 operator<=>(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
129#endif
130
131#if __cplusplus >= 201103L
132 template<typename _Alloc>
133 using _Uses = typename
134 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
135
136#if __cplusplus >= 201703L
137 // _GLIBCXX_RESOLVE_LIB_DEFECTS
138 // 2566. Requirements on the first template parameter of container
139 // adaptors
140 static_assert(is_same<_Tp, typename _Sequence::value_type>::value,
141 "value_type must be the same as the underlying container");
142#endif // C++17
143#endif // C++11
144
145 public:
146 typedef typename _Sequence::value_type value_type;
147 typedef typename _Sequence::reference reference;
148 typedef typename _Sequence::const_reference const_reference;
149 typedef typename _Sequence::size_type size_type;
150 typedef _Sequence container_type;
151
152 protected:
153 /* Maintainers wondering why this isn't uglified as per style
154 * guidelines should note that this name is specified in the standard,
155 * C++98 [23.2.3.1].
156 * (Why? Presumably for the same reason that it's protected instead
157 * of private: to allow derivation. But none of the other
158 * containers allow for derivation. Odd.)
159 */
160 /// @c c is the underlying container.
161 _Sequence c;
162
163 public:
164 /**
165 * @brief Default constructor creates no elements.
166 */
167#if __cplusplus < 201103L
168 explicit
169 queue(const _Sequence& __c = _Sequence())
170 : c(__c) { }
171#else
172 template<typename _Seq = _Sequence, typename _Requires = typename
173 enable_if<is_default_constructible<_Seq>::value>::type>
174 queue()
175 : c() { }
176
177 explicit
178 queue(const _Sequence& __c)
179 : c(__c) { }
180
181 explicit
182 queue(_Sequence&& __c)
183 : c(std::move(__c)) { }
184
185 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
186 explicit
187 queue(const _Alloc& __a)
188 : c(__a) { }
189
190 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
191 queue(const _Sequence& __c, const _Alloc& __a)
192 : c(__c, __a) { }
193
194 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
195 queue(_Sequence&& __c, const _Alloc& __a)
196 : c(std::move(__c), __a) { }
197
198 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
199 queue(const queue& __q, const _Alloc& __a)
200 : c(__q.c, __a) { }
201
202 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
203 queue(queue&& __q, const _Alloc& __a)
204 : c(std::move(__q.c), __a) { }
205#endif
206
207#ifdef __glibcxx_adaptor_iterator_pair_constructor // C++ >= 23 && HOSTED
208 template<typename _InputIterator,
209 typename = _RequireInputIter<_InputIterator>>
210 queue(_InputIterator __first, _InputIterator __last)
211 : c(__first, __last) { }
212
213 template<typename _InputIterator, typename _Alloc,
214 typename = _RequireInputIter<_InputIterator>,
215 typename = _Uses<_Alloc>>
216 queue(_InputIterator __first, _InputIterator __last, const _Alloc& __a)
217 : c(__first, __last, __a) { }
218#endif
219
220#if __glibcxx_containers_ranges // C++ >= 23
221 /**
222 * @brief Construct a queue from a range.
223 * @since C++23
224 */
225 template<__detail::__container_compatible_range<_Tp> _Rg>
226 queue(from_range_t, _Rg&& __rg)
227 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg)))
228 { }
229
230 /**
231 * @brief Construct a queue from a range.
232 * @since C++23
233 */
234 template<__detail::__container_compatible_range<_Tp> _Rg,
235 typename _Alloc>
236 queue(from_range_t, _Rg&& __rg, const _Alloc& __a)
237 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a))
238 { }
239#endif
240
241 /**
242 * Returns true if the %queue is empty.
243 */
244 _GLIBCXX_NODISCARD bool
245 empty() const
246 { return c.empty(); }
247
248 /** Returns the number of elements in the %queue. */
249 _GLIBCXX_NODISCARD
250 size_type
251 size() const
252 { return c.size(); }
253
254 /**
255 * Returns a read/write reference to the data at the first
256 * element of the %queue.
257 */
258 _GLIBCXX_NODISCARD
259 reference
260 front()
261 {
262 __glibcxx_requires_nonempty();
263 return c.front();
264 }
265
266 /**
267 * Returns a read-only (constant) reference to the data at the first
268 * element of the %queue.
269 */
270 _GLIBCXX_NODISCARD
271 const_reference
272 front() const
273 {
274 __glibcxx_requires_nonempty();
275 return c.front();
276 }
277
278 /**
279 * Returns a read/write reference to the data at the last
280 * element of the %queue.
281 */
282 _GLIBCXX_NODISCARD
283 reference
284 back()
285 {
286 __glibcxx_requires_nonempty();
287 return c.back();
288 }
289
290 /**
291 * Returns a read-only (constant) reference to the data at the last
292 * element of the %queue.
293 */
294 _GLIBCXX_NODISCARD
295 const_reference
296 back() const
297 {
298 __glibcxx_requires_nonempty();
299 return c.back();
300 }
301
302 /**
303 * @brief Add data to the end of the %queue.
304 * @param __x Data to be added.
305 *
306 * This is a typical %queue operation. The function creates an
307 * element at the end of the %queue and assigns the given data
308 * to it. The time complexity of the operation depends on the
309 * underlying sequence.
310 */
311 void
312 push(const value_type& __x)
313 { c.push_back(__x); }
314
315#if __cplusplus >= 201103L
316 void
317 push(value_type&& __x)
318 { c.push_back(std::move(__x)); }
319
320#if __cplusplus > 201402L
321 template<typename... _Args>
322 decltype(auto)
323 emplace(_Args&&... __args)
324 { return c.emplace_back(std::forward<_Args>(__args)...); }
325#else
326 template<typename... _Args>
327 void
328 emplace(_Args&&... __args)
329 { c.emplace_back(std::forward<_Args>(__args)...); }
330#endif
331#endif
332
333#if __glibcxx_containers_ranges // C++ >= 23
334 template<__detail::__container_compatible_range<_Tp> _Rg>
335 void
336 push_range(_Rg&& __rg)
337 {
338 if constexpr (requires { c.append_range(std::forward<_Rg>(__rg)); })
339 c.append_range(std::forward<_Rg>(__rg));
340 else
341 ranges::copy(__rg, std::back_inserter(c));
342 }
343#endif
344
345 /**
346 * @brief Removes first element.
347 *
348 * This is a typical %queue operation. It shrinks the %queue by one.
349 * The time complexity of the operation depends on the underlying
350 * sequence.
351 *
352 * Note that no data is returned, and if the first element's
353 * data is needed, it should be retrieved before pop() is
354 * called.
355 */
356 void
357 pop()
358 {
359 __glibcxx_requires_nonempty();
360 c.pop_front();
361 }
362
363#if __cplusplus >= 201103L
364 void
365 swap(queue& __q)
366#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
367 noexcept(__is_nothrow_swappable<_Sequence>::value)
368#else
369 noexcept(__is_nothrow_swappable<_Tp>::value)
370#endif
371 {
372 using std::swap;
373 swap(c, __q.c);
374 }
375#endif // __cplusplus >= 201103L
376
377#if __glibcxx_format_ranges
378 friend class formatter<queue<_Tp, _Sequence>, char>;
379 friend class formatter<queue<_Tp, _Sequence>, wchar_t>;
380#endif
381 };
382
383#if __cpp_deduction_guides >= 201606
384 template<typename _Container,
385 typename = _RequireNotAllocator<_Container>>
386 queue(_Container) -> queue<typename _Container::value_type, _Container>;
387
388 template<typename _Container, typename _Allocator,
389 typename = _RequireNotAllocator<_Container>>
390 queue(_Container, _Allocator)
391 -> queue<typename _Container::value_type, _Container>;
392
393#ifdef __glibcxx_adaptor_iterator_pair_constructor
394 template<typename _InputIterator,
395 typename _ValT
396 = typename iterator_traits<_InputIterator>::value_type,
397 typename = _RequireInputIter<_InputIterator>>
398 queue(_InputIterator, _InputIterator) -> queue<_ValT>;
399
400 template<typename _InputIterator, typename _Allocator,
401 typename _ValT
402 = typename iterator_traits<_InputIterator>::value_type,
403 typename = _RequireInputIter<_InputIterator>,
404 typename = _RequireAllocator<_Allocator>>
405 queue(_InputIterator, _InputIterator, _Allocator)
406 -> queue<_ValT, deque<_ValT, _Allocator>>;
407#endif
408
409#if __glibcxx_containers_ranges // C++ >= 23
410 template<ranges::input_range _Rg>
411 queue(from_range_t, _Rg&&) -> queue<ranges::range_value_t<_Rg>>;
412
413 template<ranges::input_range _Rg, __allocator_like _Alloc>
414 queue(from_range_t, _Rg&&, _Alloc)
415 -> queue<ranges::range_value_t<_Rg>,
416 deque<ranges::range_value_t<_Rg>, _Alloc>>;
417#endif
418#endif
419
420 /**
421 * @brief Queue equality comparison.
422 * @param __x A %queue.
423 * @param __y A %queue of the same type as @a __x.
424 * @return True iff the size and elements of the queues are equal.
425 *
426 * This is an equivalence relation. Complexity and semantics depend on the
427 * underlying sequence type, but the expected rules are: this relation is
428 * linear in the size of the sequences, and queues are considered equivalent
429 * if their sequences compare equal.
430 */
431 template<typename _Tp, typename _Seq>
432 _GLIBCXX_NODISCARD
433 inline bool
434 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
435 { return __x.c == __y.c; }
436
437 /**
438 * @brief Queue ordering relation.
439 * @param __x A %queue.
440 * @param __y A %queue of the same type as @a x.
441 * @return True iff @a __x is lexicographically less than @a __y.
442 *
443 * This is an total ordering relation. Complexity and semantics
444 * depend on the underlying sequence type, but the expected rules
445 * are: this relation is linear in the size of the sequences, the
446 * elements must be comparable with @c <, and
447 * std::lexicographical_compare() is usually used to make the
448 * determination.
449 */
450 template<typename _Tp, typename _Seq>
451 _GLIBCXX_NODISCARD
452 inline bool
453 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
454 { return __x.c < __y.c; }
455
456 /// Based on operator==
457 template<typename _Tp, typename _Seq>
458 _GLIBCXX_NODISCARD
459 inline bool
460 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
461 { return !(__x == __y); }
462
463 /// Based on operator<
464 template<typename _Tp, typename _Seq>
465 _GLIBCXX_NODISCARD
466 inline bool
467 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
468 { return __y < __x; }
469
470 /// Based on operator<
471 template<typename _Tp, typename _Seq>
472 _GLIBCXX_NODISCARD
473 inline bool
474 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
475 { return !(__y < __x); }
476
477 /// Based on operator<
478 template<typename _Tp, typename _Seq>
479 _GLIBCXX_NODISCARD
480 inline bool
481 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
482 { return !(__x < __y); }
483
484#if __cpp_lib_three_way_comparison
485 template<typename _Tp, three_way_comparable _Seq>
486 [[nodiscard]]
487 inline compare_three_way_result_t<_Seq>
488 operator<=>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
489 { return __x.c <=> __y.c; }
490#endif
491
492#if __cplusplus >= 201103L
493 template<typename _Tp, typename _Seq>
494 inline
495#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
496 // Constrained free swap overload, see p0185r1
497 typename enable_if<__is_swappable<_Seq>::value>::type
498#else
499 void
500#endif
501 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
502 noexcept(noexcept(__x.swap(__y)))
503 { __x.swap(__y); }
504
505 template<typename _Tp, typename _Seq, typename _Alloc>
506 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
507 : public uses_allocator<_Seq, _Alloc>::type { };
508#endif // __cplusplus >= 201103L
509
510 /**
511 * @brief A standard container automatically sorting its contents.
512 *
513 * @ingroup sequences
514 *
515 * @tparam _Tp Type of element.
516 * @tparam _Sequence Type of underlying sequence, defaults to vector<_Tp>.
517 * @tparam _Compare Comparison function object type, defaults to
518 * less<_Sequence::value_type>.
519 *
520 * This is not a true container, but an @e adaptor. It holds
521 * another container, and provides a wrapper interface to that
522 * container. The wrapper is what enforces priority-based sorting
523 * and %queue behavior. Very few of the standard container/sequence
524 * interface requirements are met (e.g., iterators).
525 *
526 * The second template parameter defines the type of the underlying
527 * sequence/container. It defaults to std::vector, but it can be
528 * any type that supports @c front(), @c push_back, @c pop_back,
529 * and random-access iterators, such as std::deque or an
530 * appropriate user-defined type.
531 *
532 * The third template parameter supplies the means of making
533 * priority comparisons. It defaults to @c less<value_type> but
534 * can be anything defining a strict weak ordering.
535 *
536 * Members not found in @a normal containers are @c container_type,
537 * which is a typedef for the second Sequence parameter, and @c
538 * push, @c pop, and @c top, which are standard %queue operations.
539 *
540 * @note No equality/comparison operators are provided for
541 * %priority_queue.
542 *
543 * @note Sorting of the elements takes place as they are added to,
544 * and removed from, the %priority_queue using the
545 * %priority_queue's member functions. If you access the elements
546 * by other means, and change their data such that the sorting
547 * order would be different, the %priority_queue will not re-sort
548 * the elements for you. (How could it know to do so?)
549 */
550 template<typename _Tp, typename _Sequence = vector<_Tp>,
551 typename _Compare = less<typename _Sequence::value_type> >
552 class priority_queue
553 {
554#ifdef _GLIBCXX_CONCEPT_CHECKS
555 // concept requirements
556 typedef typename _Sequence::value_type _Sequence_value_type;
557# if __cplusplus < 201103L
558 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
559# endif
560 __glibcxx_class_requires(_Sequence, _SequenceConcept)
561 __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
562 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
563 __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
564 _BinaryFunctionConcept)
565#endif
566
567#if __cplusplus >= 201103L
568 template<typename _Alloc>
569 using _Uses = typename
570 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
571
572#if __cplusplus >= 201703L
573 // _GLIBCXX_RESOLVE_LIB_DEFECTS
574 // 2566. Requirements on the first template parameter of container
575 // adaptors
576 static_assert(is_same<_Tp, typename _Sequence::value_type>::value,
577 "value_type must be the same as the underlying container");
578#endif // C++17
579#endif // C++11
580
581 public:
582 typedef typename _Sequence::value_type value_type;
583 typedef typename _Sequence::reference reference;
584 typedef typename _Sequence::const_reference const_reference;
585 typedef typename _Sequence::size_type size_type;
586 typedef _Sequence container_type;
587 // _GLIBCXX_RESOLVE_LIB_DEFECTS
588 // DR 2684. priority_queue lacking comparator typedef
589 typedef _Compare value_compare;
590
591 protected:
592 // See queue::c for notes on these names.
593 _Sequence c;
594 _Compare comp;
595
596 public:
597 /**
598 * @brief Default constructor creates no elements.
599 */
600#if __cplusplus < 201103L
601 explicit
602 priority_queue(const _Compare& __x = _Compare(),
603 const _Sequence& __s = _Sequence())
604 : c(__s), comp(__x)
605 { std::make_heap(c.begin(), c.end(), comp); }
606#else
607 template<typename _Seq = _Sequence, typename _Requires = typename
608 enable_if<__and_<is_default_constructible<_Compare>,
609 is_default_constructible<_Seq>>::value>::type>
610 priority_queue()
611 : c(), comp() { }
612
613 explicit
614 priority_queue(const _Compare& __x, const _Sequence& __s)
615 : c(__s), comp(__x)
616 { std::make_heap(c.begin(), c.end(), comp); }
617
618 explicit
619 priority_queue(const _Compare& __x, _Sequence&& __s = _Sequence())
620 : c(std::move(__s)), comp(__x)
621 { std::make_heap(c.begin(), c.end(), comp); }
622
623 priority_queue(const priority_queue&) = default;
624 priority_queue& operator=(const priority_queue&) = default;
625
626 priority_queue(priority_queue&& __q)
627 noexcept(__and_<is_nothrow_move_constructible<_Sequence>,
628 is_nothrow_move_constructible<_Compare>>::value)
629 : c(std::move(__q.c)), comp(std::move(__q.comp))
630 { __q.c.clear(); }
631
632 priority_queue&
633 operator=(priority_queue&& __q)
634 noexcept(__and_<is_nothrow_move_assignable<_Sequence>,
635 is_nothrow_move_assignable<_Compare>>::value)
636 {
637 c = std::move(__q.c);
638 __q.c.clear();
639 comp = std::move(__q.comp);
640 return *this;
641 }
642
643 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
644 explicit
645 priority_queue(const _Alloc& __a)
646 : c(__a), comp() { }
647
648 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
649 priority_queue(const _Compare& __x, const _Alloc& __a)
650 : c(__a), comp(__x) { }
651
652 // _GLIBCXX_RESOLVE_LIB_DEFECTS
653 // 2537. Constructors [...] taking allocators should call make_heap
654 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
655 priority_queue(const _Compare& __x, const _Sequence& __c,
656 const _Alloc& __a)
657 : c(__c, __a), comp(__x)
658 { std::make_heap(c.begin(), c.end(), comp); }
659
660 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
661 priority_queue(const _Compare& __x, _Sequence&& __c, const _Alloc& __a)
662 : c(std::move(__c), __a), comp(__x)
663 { std::make_heap(c.begin(), c.end(), comp); }
664
665 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
666 priority_queue(const priority_queue& __q, const _Alloc& __a)
667 : c(__q.c, __a), comp(__q.comp) { }
668
669 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
670 priority_queue(priority_queue&& __q, const _Alloc& __a)
671 : c(std::move(__q.c), __a), comp(std::move(__q.comp))
672 { __q.c.clear(); }
673#endif
674
675 /**
676 * @brief Builds a %queue from a range.
677 * @param __first An input iterator.
678 * @param __last An input iterator.
679 * @param __x A comparison functor describing a strict weak ordering.
680 * @param __s An initial sequence with which to start.
681 *
682 * Begins by copying @a __s, inserting a copy of the elements
683 * from @a [first,last) into the copy of @a __s, then ordering
684 * the copy according to @a __x.
685 *
686 * For more information on function objects, see the
687 * documentation on @link functors functor base classes@endlink.
688 *
689 * @{
690 */
691#if __cplusplus < 201103L
692 template<typename _InputIterator>
693 priority_queue(_InputIterator __first, _InputIterator __last,
694 const _Compare& __x = _Compare(),
695 const _Sequence& __s = _Sequence())
696 : c(__s), comp(__x)
697 {
698 __glibcxx_requires_valid_range(__first, __last);
699 c.insert(c.end(), __first, __last);
700 std::make_heap(c.begin(), c.end(), comp);
701 }
702#else
703 // _GLIBCXX_RESOLVE_LIB_DEFECTS
704 // 3529. priority_queue(first, last) should construct c with (first, last)
705 template<typename _InputIterator,
706 typename = std::_RequireInputIter<_InputIterator>>
707 priority_queue(_InputIterator __first, _InputIterator __last,
708 const _Compare& __x = _Compare())
709 : c(__first, __last), comp(__x)
710 { std::make_heap(c.begin(), c.end(), comp); }
711
712 // _GLIBCXX_RESOLVE_LIB_DEFECTS
713 // 3522. Missing requirement on InputIterator template parameter
714 template<typename _InputIterator,
715 typename = std::_RequireInputIter<_InputIterator>>
716 priority_queue(_InputIterator __first, _InputIterator __last,
717 const _Compare& __x, const _Sequence& __s)
718 : c(__s), comp(__x)
719 {
720 __glibcxx_requires_valid_range(__first, __last);
721 c.insert(c.end(), __first, __last);
722 std::make_heap(c.begin(), c.end(), comp);
723 }
724
725 template<typename _InputIterator,
726 typename = std::_RequireInputIter<_InputIterator>>
727 priority_queue(_InputIterator __first, _InputIterator __last,
728 const _Compare& __x, _Sequence&& __s)
729 : c(std::move(__s)), comp(__x)
730 {
731 __glibcxx_requires_valid_range(__first, __last);
732 c.insert(c.end(), __first, __last);
733 std::make_heap(c.begin(), c.end(), comp);
734 }
735#endif // C++11
736 /// @}
737
738#if __cplusplus >= 201103L
739 // _GLIBCXX_RESOLVE_LIB_DEFECTS
740 // 3506. Missing allocator-extended constructors for priority_queue
741 template<typename _InputIterator, typename _Alloc,
742 typename = std::_RequireInputIter<_InputIterator>,
743 typename _Requires = _Uses<_Alloc>>
744 priority_queue(_InputIterator __first, _InputIterator __last,
745 const _Alloc& __alloc)
746 : c(__first, __last, __alloc), comp()
747 { std::make_heap(c.begin(), c.end(), comp); }
748
749 template<typename _InputIterator, typename _Alloc,
750 typename = std::_RequireInputIter<_InputIterator>,
751 typename _Requires = _Uses<_Alloc>>
752 priority_queue(_InputIterator __first, _InputIterator __last,
753 const _Compare& __x, const _Alloc& __alloc)
754 : c(__first, __last, __alloc), comp(__x)
755 { std::make_heap(c.begin(), c.end(), comp); }
756
757 template<typename _InputIterator, typename _Alloc,
758 typename = std::_RequireInputIter<_InputIterator>,
759 typename _Requires = _Uses<_Alloc>>
760 priority_queue(_InputIterator __first, _InputIterator __last,
761 const _Compare& __x, const _Sequence& __s,
762 const _Alloc& __alloc)
763 : c(__s, __alloc), comp(__x)
764 {
765 __glibcxx_requires_valid_range(__first, __last);
766 c.insert(c.end(), __first, __last);
767 std::make_heap(c.begin(), c.end(), comp);
768 }
769
770 template<typename _InputIterator, typename _Alloc,
771 typename _Requires = _Uses<_Alloc>>
772 priority_queue(_InputIterator __first, _InputIterator __last,
773 const _Compare& __x, _Sequence&& __s,
774 const _Alloc& __alloc)
775 : c(std::move(__s), __alloc), comp(__x)
776 {
777 __glibcxx_requires_valid_range(__first, __last);
778 c.insert(c.end(), __first, __last);
779 std::make_heap(c.begin(), c.end(), comp);
780 }
781#endif // C++11
782
783#if __glibcxx_containers_ranges // C++ >= 23
784 /**
785 * @brief Construct a priority_queue from a range.
786 * @since C++23
787 *
788 * @{
789 */
790 template<__detail::__container_compatible_range<_Tp> _Rg>
791 priority_queue(from_range_t, _Rg&& __rg,
792 const _Compare& __x = _Compare())
793 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg))), comp(__x)
794 { std::make_heap(c.begin(), c.end(), comp); }
795
796 template<__detail::__container_compatible_range<_Tp> _Rg, typename _Alloc>
797 priority_queue(from_range_t, _Rg&& __rg, const _Compare& __x,
798 const _Alloc& __a)
799 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a)), comp(__x)
800 { std::make_heap(c.begin(), c.end(), comp); }
801
802 template<__detail::__container_compatible_range<_Tp> _Rg, typename _Alloc>
803 priority_queue(from_range_t, _Rg&& __rg, const _Alloc& __a)
804 : c(ranges::to<_Sequence>(std::forward<_Rg>(__rg), __a)), comp()
805 { std::make_heap(c.begin(), c.end(), comp); }
806 /// @}
807#endif
808
809 /**
810 * Returns true if the %queue is empty.
811 */
812 _GLIBCXX_NODISCARD bool
813 empty() const
814 { return c.empty(); }
815
816 /** Returns the number of elements in the %queue. */
817 _GLIBCXX_NODISCARD
818 size_type
819 size() const
820 { return c.size(); }
821
822 /**
823 * Returns a read-only (constant) reference to the data at the first
824 * element of the %queue.
825 */
826 _GLIBCXX_NODISCARD
827 const_reference
828 top() const
829 {
830 __glibcxx_requires_nonempty();
831 return c.front();
832 }
833
834 /**
835 * @brief Add data to the %queue.
836 * @param __x Data to be added.
837 *
838 * This is a typical %queue operation.
839 * The time complexity of the operation depends on the underlying
840 * sequence.
841 */
842 void
843 push(const value_type& __x)
844 {
845 c.push_back(__x);
846 std::push_heap(c.begin(), c.end(), comp);
847 }
848
849#if __cplusplus >= 201103L
850 void
851 push(value_type&& __x)
852 {
853 c.push_back(std::move(__x));
854 std::push_heap(c.begin(), c.end(), comp);
855 }
856
857 template<typename... _Args>
858 void
859 emplace(_Args&&... __args)
860 {
861 c.emplace_back(std::forward<_Args>(__args)...);
862 std::push_heap(c.begin(), c.end(), comp);
863 }
864#endif
865
866#if __glibcxx_containers_ranges // C++ >= 23
867 template<__detail::__container_compatible_range<_Tp> _Rg>
868 void
869 push_range(_Rg&& __rg)
870 {
871 if constexpr (requires { c.append_range(std::forward<_Rg>(__rg)); })
872 c.append_range(std::forward<_Rg>(__rg));
873 else
874 ranges::copy(__rg, std::back_inserter(c));
875 std::make_heap(c.begin(), c.end(), comp);
876 }
877#endif
878
879 /**
880 * @brief Removes first element.
881 *
882 * This is a typical %queue operation. It shrinks the %queue
883 * by one. The time complexity of the operation depends on the
884 * underlying sequence.
885 *
886 * Note that no data is returned, and if the first element's
887 * data is needed, it should be retrieved before pop() is
888 * called.
889 */
890 void
891 pop()
892 {
893 __glibcxx_requires_nonempty();
894 std::pop_heap(c.begin(), c.end(), comp);
895 c.pop_back();
896 }
897
898#if __cplusplus >= 201103L
899 void
900 swap(priority_queue& __pq)
901 noexcept(__and_<
902#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
903 __is_nothrow_swappable<_Sequence>,
904#else
905 __is_nothrow_swappable<_Tp>,
906#endif
907 __is_nothrow_swappable<_Compare>
908 >::value)
909 {
910 using std::swap;
911 swap(c, __pq.c);
912 swap(comp, __pq.comp);
913 }
914#endif // __cplusplus >= 201103L
915
916#if __glibcxx_format_ranges
917 friend class formatter<priority_queue<_Tp, _Sequence, _Compare>, char>;
918 friend class formatter<priority_queue<_Tp, _Sequence, _Compare>, wchar_t>;
919#endif
920 };
921
922#if __cpp_deduction_guides >= 201606
923 template<typename _Compare, typename _Container,
924 typename = _RequireNotAllocator<_Compare>,
925 typename = _RequireNotAllocator<_Container>>
926 priority_queue(_Compare, _Container)
927 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
928
929 template<typename _InputIterator, typename _ValT
930 = typename iterator_traits<_InputIterator>::value_type,
931 typename _Compare = less<_ValT>,
932 typename _Container = vector<_ValT>,
933 typename = _RequireInputIter<_InputIterator>,
934 typename = _RequireNotAllocator<_Compare>,
935 typename = _RequireNotAllocator<_Container>>
936 priority_queue(_InputIterator, _InputIterator, _Compare = _Compare(),
937 _Container = _Container())
938 -> priority_queue<_ValT, _Container, _Compare>;
939
940 template<typename _Compare, typename _Container, typename _Allocator,
941 typename = _RequireNotAllocator<_Compare>,
942 typename = _RequireNotAllocator<_Container>>
943 priority_queue(_Compare, _Container, _Allocator)
944 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
945
946#if __glibcxx_containers_ranges // C++ >= 23
947 template<ranges::input_range _Rg,
948 __not_allocator_like _Compare = less<ranges::range_value_t<_Rg>>,
949 __allocator_like _Alloc = std::allocator<ranges::range_value_t<_Rg>>>
950 priority_queue(from_range_t, _Rg&&, _Compare = _Compare(),
951 _Alloc = _Alloc())
952 -> priority_queue<ranges::range_value_t<_Rg>,
953 vector<ranges::range_value_t<_Rg>, _Alloc>,
954 _Compare>;
955
956 template<ranges::input_range _Rg, __allocator_like _Alloc>
957 priority_queue(from_range_t, _Rg&&, _Alloc)
958 -> priority_queue<ranges::range_value_t<_Rg>,
959 vector<ranges::range_value_t<_Rg>, _Alloc>>;
960#endif
961#endif
962
963 // No equality/comparison operators are provided for priority_queue.
964
965#if __cplusplus >= 201103L
966 template<typename _Tp, typename _Sequence, typename _Compare>
967 inline
968#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
969 // Constrained free swap overload, see p0185r1
970 typename enable_if<__and_<__is_swappable<_Sequence>,
971 __is_swappable<_Compare>>::value>::type
972#else
973 void
974#endif
975 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
976 priority_queue<_Tp, _Sequence, _Compare>& __y)
977 noexcept(noexcept(__x.swap(__y)))
978 { __x.swap(__y); }
979
980 template<typename _Tp, typename _Sequence, typename _Compare,
981 typename _Alloc>
982 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
983 : public uses_allocator<_Sequence, _Alloc>::type { };
984#endif // __cplusplus >= 201103L
985
986_GLIBCXX_END_NAMESPACE_VERSION
987} // namespace
988
989#endif /* _STL_QUEUE_H */
ranges
concept_check.h
ranges_algobase.h
debug.h
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition move.h:138
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition move.h:72
std::back_inserter
constexpr back_insert_iterator< _Container > back_inserter(_Container &__x)
Definition bits/stl_iterator.h:764
std
ISO C++ entities toplevel namespace is std.
std::compare_three_way_result_t
typename __detail::__cmp3way_res_impl< _Tp, _Up >::type compare_three_way_result_t
[cmp.result], result of three-way comparison
Definition compare:547
std::enable_if
Define a member typedef type only if a boolean constant is true.
Definition type_traits:137
std::is_same
is_same
Definition type_traits:1626
std::is_default_constructible
is_default_constructible
Definition type_traits:1251
std::size_type
std::value_type
std::uses_allocator
Declare uses_allocator so it can be specialized in <queue> etc.
Definition memoryfwd.h:76
std::deque
A standard container using fixed-size memory allocation and constant-time manipulation of elements at...
Definition stl_deque.h:791
std::less
One of the comparison functors.
Definition stl_function.h:404
std::queue
A standard container giving FIFO behavior.
Definition stl_queue.h:105
std::queue::push
void push(const value_type &__x)
Add data to the end of the queue.
Definition stl_queue.h:312
std::queue::c
_Sequence c
c is the underlying container.
Definition stl_queue.h:161
std::queue::size
size_type size() const
Definition stl_queue.h:251
std::queue::front
reference front()
Definition stl_queue.h:260
std::queue::back
const_reference back() const
Definition stl_queue.h:296
std::queue::pop
void pop()
Removes first element.
Definition stl_queue.h:357
std::queue::queue
queue()
Default constructor creates no elements.
Definition stl_queue.h:174
std::queue::front
const_reference front() const
Definition stl_queue.h:272
std::queue::empty
bool empty() const
Definition stl_queue.h:245
std::queue::back
reference back()
Definition stl_queue.h:284
std::priority_queue
A standard container automatically sorting its contents.
Definition stl_queue.h:553
std::priority_queue::size
size_type size() const
Definition stl_queue.h:819
std::priority_queue::priority_queue
priority_queue(_InputIterator __first, _InputIterator __last, const _Compare &__x, _Sequence &&__s)
Builds a queue from a range.
Definition stl_queue.h:727
std::priority_queue::empty
bool empty() const
Definition stl_queue.h:813
std::priority_queue::pop
void pop()
Removes first element.
Definition stl_queue.h:891
std::priority_queue::top
const_reference top() const
Definition stl_queue.h:828
std::priority_queue::priority_queue
priority_queue(_InputIterator __first, _InputIterator __last, const _Compare &__x, const _Sequence &__s)
Builds a queue from a range.
Definition stl_queue.h:716
std::priority_queue::priority_queue
priority_queue(_InputIterator __first, _InputIterator __last, const _Compare &__x=_Compare())
Builds a queue from a range.
Definition stl_queue.h:707
std::priority_queue::push
void push(const value_type &__x)
Add data to the queue.
Definition stl_queue.h:843
std::priority_queue::priority_queue
priority_queue()
Default constructor creates no elements.
Definition stl_queue.h:610
std::vector
A standard container which offers fixed time access to individual elements in any order.
Definition stl_vector.h:461
std::ranges::input_range
A range for which ranges::begin returns an input iterator.
Definition ranges_base.h:599