1 // Queue implementation -*- C++ -*-
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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}
57 #define _STL_QUEUE_H 1
59 #include <bits/concept_check.h>
60 #include <debug/debug.h>
61 #if __cplusplus >= 201103L
62 # include <bits/uses_allocator.h>
65 namespace std _GLIBCXX_VISIBILITY(default)
67 _GLIBCXX_BEGIN_NAMESPACE_VERSION
70 * @brief A standard container giving FIFO behavior.
74 * @tparam _Tp Type of element.
75 * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>.
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.
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.
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.
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.
95 template<typename _Tp, typename _Sequence = deque<_Tp> >
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)
104 __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
105 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
106 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
109 template<typename _Tp1, typename _Seq1>
111 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
113 template<typename _Tp1, typename _Seq1>
115 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
117 #if __cplusplus >= 201103L
118 template<typename _Alloc>
119 using _Uses = typename
120 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
124 typedef typename _Sequence::value_type value_type;
125 typedef typename _Sequence::reference reference;
126 typedef typename _Sequence::const_reference const_reference;
127 typedef typename _Sequence::size_type size_type;
128 typedef _Sequence container_type;
131 /* Maintainers wondering why this isn't uglified as per style
132 * guidelines should note that this name is specified in the standard,
134 * (Why? Presumably for the same reason that it's protected instead
135 * of private: to allow derivation. But none of the other
136 * containers allow for derivation. Odd.)
138 /// @c c is the underlying container.
143 * @brief Default constructor creates no elements.
145 #if __cplusplus < 201103L
147 queue(const _Sequence& __c = _Sequence())
150 template<typename _Seq = _Sequence, typename _Requires = typename
151 enable_if<is_default_constructible<_Seq>::value>::type>
156 queue(const _Sequence& __c)
160 queue(_Sequence&& __c)
161 : c(std::move(__c)) { }
163 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
165 queue(const _Alloc& __a)
168 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
169 queue(const _Sequence& __c, const _Alloc& __a)
172 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
173 queue(_Sequence&& __c, const _Alloc& __a)
174 : c(std::move(__c), __a) { }
176 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
177 queue(const queue& __q, const _Alloc& __a)
180 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
181 queue(queue&& __q, const _Alloc& __a)
182 : c(std::move(__q.c), __a) { }
186 * Returns true if the %queue is empty.
190 { return c.empty(); }
192 /** Returns the number of elements in the %queue. */
198 * Returns a read/write reference to the data at the first
199 * element of the %queue.
204 __glibcxx_requires_nonempty();
209 * Returns a read-only (constant) reference to the data at the first
210 * element of the %queue.
215 __glibcxx_requires_nonempty();
220 * Returns a read/write reference to the data at the last
221 * element of the %queue.
226 __glibcxx_requires_nonempty();
231 * Returns a read-only (constant) reference to the data at the last
232 * element of the %queue.
237 __glibcxx_requires_nonempty();
242 * @brief Add data to the end of the %queue.
243 * @param __x Data to be added.
245 * This is a typical %queue operation. The function creates an
246 * element at the end of the %queue and assigns the given data
247 * to it. The time complexity of the operation depends on the
248 * underlying sequence.
251 push(const value_type& __x)
252 { c.push_back(__x); }
254 #if __cplusplus >= 201103L
256 push(value_type&& __x)
257 { c.push_back(std::move(__x)); }
259 #if __cplusplus > 201402L
260 template<typename... _Args>
262 emplace(_Args&&... __args)
263 { return c.emplace_back(std::forward<_Args>(__args)...); }
265 template<typename... _Args>
267 emplace(_Args&&... __args)
268 { c.emplace_back(std::forward<_Args>(__args)...); }
273 * @brief Removes first element.
275 * This is a typical %queue operation. It shrinks the %queue by one.
276 * The time complexity of the operation depends on the underlying
279 * Note that no data is returned, and if the first element's
280 * data is needed, it should be retrieved before pop() is
286 __glibcxx_requires_nonempty();
290 #if __cplusplus >= 201103L
293 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
294 noexcept(__is_nothrow_swappable<_Sequence>::value)
296 noexcept(__is_nothrow_swappable<_Tp>::value)
302 #endif // __cplusplus >= 201103L
305 #if __cpp_deduction_guides >= 201606
306 template<typename _Container,
307 typename = enable_if_t<!__is_allocator<_Container>::value>>
308 queue(_Container) -> queue<typename _Container::value_type, _Container>;
310 template<typename _Container, typename _Allocator,
311 typename = enable_if_t<!__is_allocator<_Container>::value>,
312 typename = enable_if_t<__is_allocator<_Allocator>::value>>
313 queue(_Container, _Allocator)
314 -> queue<typename _Container::value_type, _Container>;
318 * @brief Queue equality comparison.
319 * @param __x A %queue.
320 * @param __y A %queue of the same type as @a __x.
321 * @return True iff the size and elements of the queues are equal.
323 * This is an equivalence relation. Complexity and semantics depend on the
324 * underlying sequence type, but the expected rules are: this relation is
325 * linear in the size of the sequences, and queues are considered equivalent
326 * if their sequences compare equal.
328 template<typename _Tp, typename _Seq>
330 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
331 { return __x.c == __y.c; }
334 * @brief Queue ordering relation.
335 * @param __x A %queue.
336 * @param __y A %queue of the same type as @a x.
337 * @return True iff @a __x is lexicographically less than @a __y.
339 * This is an total ordering relation. Complexity and semantics
340 * depend on the underlying sequence type, but the expected rules
341 * are: this relation is linear in the size of the sequences, the
342 * elements must be comparable with @c <, and
343 * std::lexicographical_compare() is usually used to make the
346 template<typename _Tp, typename _Seq>
348 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
349 { return __x.c < __y.c; }
351 /// Based on operator==
352 template<typename _Tp, typename _Seq>
354 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
355 { return !(__x == __y); }
357 /// Based on operator<
358 template<typename _Tp, typename _Seq>
360 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
361 { return __y < __x; }
363 /// Based on operator<
364 template<typename _Tp, typename _Seq>
366 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
367 { return !(__y < __x); }
369 /// Based on operator<
370 template<typename _Tp, typename _Seq>
372 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
373 { return !(__x < __y); }
375 #if __cplusplus >= 201103L
376 template<typename _Tp, typename _Seq>
378 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
379 // Constrained free swap overload, see p0185r1
380 typename enable_if<__is_swappable<_Seq>::value>::type
384 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
385 noexcept(noexcept(__x.swap(__y)))
388 template<typename _Tp, typename _Seq, typename _Alloc>
389 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
390 : public uses_allocator<_Seq, _Alloc>::type { };
391 #endif // __cplusplus >= 201103L
394 * @brief A standard container automatically sorting its contents.
398 * @tparam _Tp Type of element.
399 * @tparam _Sequence Type of underlying sequence, defaults to vector<_Tp>.
400 * @tparam _Compare Comparison function object type, defaults to
401 * less<_Sequence::value_type>.
403 * This is not a true container, but an @e adaptor. It holds
404 * another container, and provides a wrapper interface to that
405 * container. The wrapper is what enforces priority-based sorting
406 * and %queue behavior. Very few of the standard container/sequence
407 * interface requirements are met (e.g., iterators).
409 * The second template parameter defines the type of the underlying
410 * sequence/container. It defaults to std::vector, but it can be
411 * any type that supports @c front(), @c push_back, @c pop_back,
412 * and random-access iterators, such as std::deque or an
413 * appropriate user-defined type.
415 * The third template parameter supplies the means of making
416 * priority comparisons. It defaults to @c less<value_type> but
417 * can be anything defining a strict weak ordering.
419 * Members not found in @a normal containers are @c container_type,
420 * which is a typedef for the second Sequence parameter, and @c
421 * push, @c pop, and @c top, which are standard %queue operations.
423 * @note No equality/comparison operators are provided for
426 * @note Sorting of the elements takes place as they are added to,
427 * and removed from, the %priority_queue using the
428 * %priority_queue's member functions. If you access the elements
429 * by other means, and change their data such that the sorting
430 * order would be different, the %priority_queue will not re-sort
431 * the elements for you. (How could it know to do so?)
433 template<typename _Tp, typename _Sequence = vector<_Tp>,
434 typename _Compare = less<typename _Sequence::value_type> >
437 #ifdef _GLIBCXX_CONCEPT_CHECKS
438 // concept requirements
439 typedef typename _Sequence::value_type _Sequence_value_type;
440 # if __cplusplus < 201103L
441 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
443 __glibcxx_class_requires(_Sequence, _SequenceConcept)
444 __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
445 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
446 __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
447 _BinaryFunctionConcept)
450 #if __cplusplus >= 201103L
451 template<typename _Alloc>
452 using _Uses = typename
453 enable_if<uses_allocator<_Sequence, _Alloc>::value>::type;
457 typedef typename _Sequence::value_type value_type;
458 typedef typename _Sequence::reference reference;
459 typedef typename _Sequence::const_reference const_reference;
460 typedef typename _Sequence::size_type size_type;
461 typedef _Sequence container_type;
462 // _GLIBCXX_RESOLVE_LIB_DEFECTS
463 // DR 2684. priority_queue lacking comparator typedef
464 typedef _Compare value_compare;
467 // See queue::c for notes on these names.
473 * @brief Default constructor creates no elements.
475 #if __cplusplus < 201103L
477 priority_queue(const _Compare& __x = _Compare(),
478 const _Sequence& __s = _Sequence())
480 { std::make_heap(c.begin(), c.end(), comp); }
482 template<typename _Seq = _Sequence, typename _Requires = typename
483 enable_if<__and_<is_default_constructible<_Compare>,
484 is_default_constructible<_Seq>>::value>::type>
489 priority_queue(const _Compare& __x, const _Sequence& __s)
491 { std::make_heap(c.begin(), c.end(), comp); }
494 priority_queue(const _Compare& __x, _Sequence&& __s = _Sequence())
495 : c(std::move(__s)), comp(__x)
496 { std::make_heap(c.begin(), c.end(), comp); }
498 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
500 priority_queue(const _Alloc& __a)
503 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
504 priority_queue(const _Compare& __x, const _Alloc& __a)
505 : c(__a), comp(__x) { }
507 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
508 priority_queue(const _Compare& __x, const _Sequence& __c,
510 : c(__c, __a), comp(__x) { }
512 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
513 priority_queue(const _Compare& __x, _Sequence&& __c, const _Alloc& __a)
514 : c(std::move(__c), __a), comp(__x) { }
516 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
517 priority_queue(const priority_queue& __q, const _Alloc& __a)
518 : c(__q.c, __a), comp(__q.comp) { }
520 template<typename _Alloc, typename _Requires = _Uses<_Alloc>>
521 priority_queue(priority_queue&& __q, const _Alloc& __a)
522 : c(std::move(__q.c), __a), comp(std::move(__q.comp)) { }
526 * @brief Builds a %queue from a range.
527 * @param __first An input iterator.
528 * @param __last An input iterator.
529 * @param __x A comparison functor describing a strict weak ordering.
530 * @param __s An initial sequence with which to start.
532 * Begins by copying @a __s, inserting a copy of the elements
533 * from @a [first,last) into the copy of @a __s, then ordering
534 * the copy according to @a __x.
536 * For more information on function objects, see the
537 * documentation on @link functors functor base
540 #if __cplusplus < 201103L
541 template<typename _InputIterator>
542 priority_queue(_InputIterator __first, _InputIterator __last,
543 const _Compare& __x = _Compare(),
544 const _Sequence& __s = _Sequence())
547 __glibcxx_requires_valid_range(__first, __last);
548 c.insert(c.end(), __first, __last);
549 std::make_heap(c.begin(), c.end(), comp);
552 template<typename _InputIterator>
553 priority_queue(_InputIterator __first, _InputIterator __last,
555 const _Sequence& __s)
558 __glibcxx_requires_valid_range(__first, __last);
559 c.insert(c.end(), __first, __last);
560 std::make_heap(c.begin(), c.end(), comp);
563 template<typename _InputIterator>
564 priority_queue(_InputIterator __first, _InputIterator __last,
565 const _Compare& __x = _Compare(),
566 _Sequence&& __s = _Sequence())
567 : c(std::move(__s)), comp(__x)
569 __glibcxx_requires_valid_range(__first, __last);
570 c.insert(c.end(), __first, __last);
571 std::make_heap(c.begin(), c.end(), comp);
576 * Returns true if the %queue is empty.
580 { return c.empty(); }
582 /** Returns the number of elements in the %queue. */
588 * Returns a read-only (constant) reference to the data at the first
589 * element of the %queue.
594 __glibcxx_requires_nonempty();
599 * @brief Add data to the %queue.
600 * @param __x Data to be added.
602 * This is a typical %queue operation.
603 * The time complexity of the operation depends on the underlying
607 push(const value_type& __x)
610 std::push_heap(c.begin(), c.end(), comp);
613 #if __cplusplus >= 201103L
615 push(value_type&& __x)
617 c.push_back(std::move(__x));
618 std::push_heap(c.begin(), c.end(), comp);
621 template<typename... _Args>
623 emplace(_Args&&... __args)
625 c.emplace_back(std::forward<_Args>(__args)...);
626 std::push_heap(c.begin(), c.end(), comp);
631 * @brief Removes first element.
633 * This is a typical %queue operation. It shrinks the %queue
634 * by one. The time complexity of the operation depends on the
635 * underlying sequence.
637 * Note that no data is returned, and if the first element's
638 * data is needed, it should be retrieved before pop() is
644 __glibcxx_requires_nonempty();
645 std::pop_heap(c.begin(), c.end(), comp);
649 #if __cplusplus >= 201103L
651 swap(priority_queue& __pq)
653 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
654 __is_nothrow_swappable<_Sequence>,
656 __is_nothrow_swappable<_Tp>,
658 __is_nothrow_swappable<_Compare>
663 swap(comp, __pq.comp);
665 #endif // __cplusplus >= 201103L
668 #if __cpp_deduction_guides >= 201606
669 template<typename _Compare, typename _Container,
670 typename = enable_if_t<!__is_allocator<_Compare>::value>,
671 typename = enable_if_t<!__is_allocator<_Container>::value>>
672 priority_queue(_Compare, _Container)
673 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
675 template<typename _InputIterator, typename _ValT
676 = typename iterator_traits<_InputIterator>::value_type,
677 typename _Compare = less<_ValT>,
678 typename _Container = vector<_ValT>,
679 typename = _RequireInputIter<_InputIterator>,
680 typename = enable_if_t<!__is_allocator<_Compare>::value>,
681 typename = enable_if_t<!__is_allocator<_Container>::value>>
682 priority_queue(_InputIterator, _InputIterator, _Compare = _Compare(),
683 _Container = _Container())
684 -> priority_queue<_ValT, _Container, _Compare>;
686 template<typename _Compare, typename _Container, typename _Allocator,
687 typename = enable_if_t<!__is_allocator<_Compare>::value>,
688 typename = enable_if_t<!__is_allocator<_Container>::value>,
689 typename = enable_if_t<__is_allocator<_Allocator>::value>>
690 priority_queue(_Compare, _Container, _Allocator)
691 -> priority_queue<typename _Container::value_type, _Container, _Compare>;
694 // No equality/comparison operators are provided for priority_queue.
696 #if __cplusplus >= 201103L
697 template<typename _Tp, typename _Sequence, typename _Compare>
699 #if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
700 // Constrained free swap overload, see p0185r1
701 typename enable_if<__and_<__is_swappable<_Sequence>,
702 __is_swappable<_Compare>>::value>::type
706 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
707 priority_queue<_Tp, _Sequence, _Compare>& __y)
708 noexcept(noexcept(__x.swap(__y)))
711 template<typename _Tp, typename _Sequence, typename _Compare,
713 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
714 : public uses_allocator<_Sequence, _Alloc>::type { };
715 #endif // __cplusplus >= 201103L
717 _GLIBCXX_END_NAMESPACE_VERSION
720 #endif /* _STL_QUEUE_H */