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.
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.
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 */