1 // Queue implementation -*- C++ -*-
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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}
59 #define _STL_QUEUE_H 1
61 #include <bits/concept_check.h>
62 #include <debug/debug.h>
64 namespace std _GLIBCXX_VISIBILITY(default)
66 _GLIBCXX_BEGIN_NAMESPACE_VERSION
69 * @brief A standard container giving FIFO behavior.
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.
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.
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.
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.
91 template<typename _Tp, typename _Sequence = deque<_Tp> >
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)
101 template<typename _Tp1, typename _Seq1>
103 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
105 template<typename _Tp1, typename _Seq1>
107 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
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;
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.)
129 * @brief Default constructor creates no elements.
131 #ifndef __GXX_EXPERIMENTAL_CXX0X__
133 queue(const _Sequence& __c = _Sequence())
137 queue(const _Sequence& __c)
141 queue(_Sequence&& __c = _Sequence())
142 : c(std::move(__c)) { }
146 * Returns true if the %queue is empty.
150 { return c.empty(); }
152 /** Returns the number of elements in the %queue. */
158 * Returns a read/write reference to the data at the first
159 * element of the %queue.
164 __glibcxx_requires_nonempty();
169 * Returns a read-only (constant) reference to the data at the first
170 * element of the %queue.
175 __glibcxx_requires_nonempty();
180 * Returns a read/write reference to the data at the last
181 * element of the %queue.
186 __glibcxx_requires_nonempty();
191 * Returns a read-only (constant) reference to the data at the last
192 * element of the %queue.
197 __glibcxx_requires_nonempty();
202 * @brief Add data to the end of the %queue.
203 * @param __x Data to be added.
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.
211 push(const value_type& __x)
212 { c.push_back(__x); }
214 #ifdef __GXX_EXPERIMENTAL_CXX0X__
216 push(value_type&& __x)
217 { c.push_back(std::move(__x)); }
219 template<typename... _Args>
221 emplace(_Args&&... __args)
222 { c.emplace_back(std::forward<_Args>(__args)...); }
226 * @brief Removes first element.
228 * This is a typical %queue operation. It shrinks the %queue by one.
229 * The time complexity of the operation depends on the underlying
232 * Note that no data is returned, and if the first element's
233 * data is needed, it should be retrieved before pop() is
239 __glibcxx_requires_nonempty();
243 #ifdef __GXX_EXPERIMENTAL_CXX0X__
246 noexcept(noexcept(swap(c, __q.c)))
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.
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.
265 template<typename _Tp, typename _Seq>
267 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
268 { return __x.c == __y.c; }
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.
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
283 template<typename _Tp, typename _Seq>
285 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
286 { return __x.c < __y.c; }
288 /// Based on operator==
289 template<typename _Tp, typename _Seq>
291 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
292 { return !(__x == __y); }
294 /// Based on operator<
295 template<typename _Tp, typename _Seq>
297 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
298 { return __y < __x; }
300 /// Based on operator<
301 template<typename _Tp, typename _Seq>
303 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
304 { return !(__y < __x); }
306 /// Based on operator<
307 template<typename _Tp, typename _Seq>
309 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
310 { return !(__x < __y); }
312 #ifdef __GXX_EXPERIMENTAL_CXX0X__
313 template<typename _Tp, typename _Seq>
315 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
316 noexcept(noexcept(__x.swap(__y)))
319 template<typename _Tp, typename _Seq, typename _Alloc>
320 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
321 : public uses_allocator<_Seq, _Alloc>::type { };
325 * @brief A standard container automatically sorting its contents.
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).
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.
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.
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.
349 * @note No equality/comparison operators are provided for
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?)
359 template<typename _Tp, typename _Sequence = vector<_Tp>,
360 typename _Compare = less<typename _Sequence::value_type> >
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)
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;
380 // See queue::c for notes on these names.
386 * @brief Default constructor creates no elements.
388 #ifndef __GXX_EXPERIMENTAL_CXX0X__
390 priority_queue(const _Compare& __x = _Compare(),
391 const _Sequence& __s = _Sequence())
393 { std::make_heap(c.begin(), c.end(), comp); }
396 priority_queue(const _Compare& __x,
397 const _Sequence& __s)
399 { std::make_heap(c.begin(), c.end(), comp); }
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); }
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.
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.
419 * For more information on function objects, see the
420 * documentation on @link functors functor base
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())
430 __glibcxx_requires_valid_range(__first, __last);
431 c.insert(c.end(), __first, __last);
432 std::make_heap(c.begin(), c.end(), comp);
435 template<typename _InputIterator>
436 priority_queue(_InputIterator __first, _InputIterator __last,
438 const _Sequence& __s)
441 __glibcxx_requires_valid_range(__first, __last);
442 c.insert(c.end(), __first, __last);
443 std::make_heap(c.begin(), c.end(), comp);
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)
452 __glibcxx_requires_valid_range(__first, __last);
453 c.insert(c.end(), __first, __last);
454 std::make_heap(c.begin(), c.end(), comp);
459 * Returns true if the %queue is empty.
463 { return c.empty(); }
465 /** Returns the number of elements in the %queue. */
471 * Returns a read-only (constant) reference to the data at the first
472 * element of the %queue.
477 __glibcxx_requires_nonempty();
482 * @brief Add data to the %queue.
483 * @param __x Data to be added.
485 * This is a typical %queue operation.
486 * The time complexity of the operation depends on the underlying
490 push(const value_type& __x)
493 std::push_heap(c.begin(), c.end(), comp);
496 #ifdef __GXX_EXPERIMENTAL_CXX0X__
498 push(value_type&& __x)
500 c.push_back(std::move(__x));
501 std::push_heap(c.begin(), c.end(), comp);
504 template<typename... _Args>
506 emplace(_Args&&... __args)
508 c.emplace_back(std::forward<_Args>(__args)...);
509 std::push_heap(c.begin(), c.end(), comp);
514 * @brief Removes first element.
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.
520 * Note that no data is returned, and if the first element's
521 * data is needed, it should be retrieved before pop() is
527 __glibcxx_requires_nonempty();
528 std::pop_heap(c.begin(), c.end(), comp);
532 #ifdef __GXX_EXPERIMENTAL_CXX0X__
534 swap(priority_queue& __pq)
535 noexcept(noexcept(swap(c, __pq.c)) && noexcept(swap(comp, __pq.comp)))
539 swap(comp, __pq.comp);
544 // No equality/comparison operators are provided for priority_queue.
546 #ifdef __GXX_EXPERIMENTAL_CXX0X__
547 template<typename _Tp, typename _Sequence, typename _Compare>
549 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
550 priority_queue<_Tp, _Sequence, _Compare>& __y)
551 noexcept(noexcept(__x.swap(__y)))
554 template<typename _Tp, typename _Sequence, typename _Compare,
556 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
557 : public uses_allocator<_Sequence, _Alloc>::type { };
560 _GLIBCXX_END_NAMESPACE_VERSION
563 #endif /* _STL_QUEUE_H */