libstdc++

stl_queue.h
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1 // Queue implementation -*- C++ -*-
2
3 // Copyright (C) 2001-2013 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
62 namespace std _GLIBCXX_VISIBILITY(default)
63 {
64 _GLIBCXX_BEGIN_NAMESPACE_VERSION
65
66 /**
67 * @brief A standard container giving FIFO behavior.
68 *
69 * @ingroup sequences
70 *
71 * @tparam _Tp Type of element.
72 * @tparam _Sequence Type of underlying sequence, defaults to deque<_Tp>.
73 *
74 * Meets many of the requirements of a
75 * <a href="tables.html#65">container</a>,
76 * but does not define anything to do with iterators. Very few of the
77 * other standard container interfaces are defined.
78 *
79 * This is not a true container, but an @e adaptor. It holds another
80 * container, and provides a wrapper interface to that container. The
81 * wrapper is what enforces strict first-in-first-out %queue behavior.
82 *
83 * The second template parameter defines the type of the underlying
84 * sequence/container. It defaults to std::deque, but it can be any type
85 * that supports @c front, @c back, @c push_back, and @c pop_front,
86 * such as std::list or an appropriate user-defined type.
87 *
88 * Members not found in @a normal containers are @c container_type,
89 * which is a typedef for the second Sequence parameter, and @c push and
90 * @c pop, which are standard %queue/FIFO operations.
91 */
92 template<typename _Tp, typename _Sequence = deque<_Tp> >
93 class queue
94 {
95 // concept requirements
96 typedef typename _Sequence::value_type _Sequence_value_type;
97 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
98 __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
99 __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
100 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
101
102 template<typename _Tp1, typename _Seq1>
103 friend bool
104 operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
105
106 template<typename _Tp1, typename _Seq1>
107 friend bool
108 operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
109
110 public:
111 typedef typename _Sequence::value_type value_type;
112 typedef typename _Sequence::reference reference;
113 typedef typename _Sequence::const_reference const_reference;
114 typedef typename _Sequence::size_type size_type;
115 typedef _Sequence container_type;
116
117 protected:
118 /**
119 * 'c' is the underlying container. Maintainers wondering why
120 * this isn't uglified as per style guidelines should note that
121 * this name is specified in the standard, [23.2.3.1]. (Why?
122 * Presumably for the same reason that it's protected instead
123 * of private: to allow derivation. But none of the other
124 * containers allow for derivation. Odd.)
125 */
126 _Sequence c;
127
128 public:
129 /**
130 * @brief Default constructor creates no elements.
131 */
132 #if __cplusplus < 201103L
133 explicit
134 queue(const _Sequence& __c = _Sequence())
135 : c(__c) { }
136 #else
137 explicit
138 queue(const _Sequence& __c)
139 : c(__c) { }
140
141 explicit
142 queue(_Sequence&& __c = _Sequence())
143 : c(std::move(__c)) { }
144 #endif
145
146 /**
147 * Returns true if the %queue is empty.
148 */
149 bool
150 empty() const
151 { return c.empty(); }
152
153 /** Returns the number of elements in the %queue. */
154 size_type
155 size() const
156 { return c.size(); }
157
158 /**
159 * Returns a read/write reference to the data at the first
160 * element of the %queue.
161 */
162 reference
163 front()
164 {
165 __glibcxx_requires_nonempty();
166 return c.front();
167 }
168
169 /**
170 * Returns a read-only (constant) reference to the data at the first
171 * element of the %queue.
172 */
173 const_reference
174 front() const
175 {
176 __glibcxx_requires_nonempty();
177 return c.front();
178 }
179
180 /**
181 * Returns a read/write reference to the data at the last
182 * element of the %queue.
183 */
184 reference
185 back()
186 {
187 __glibcxx_requires_nonempty();
188 return c.back();
189 }
190
191 /**
192 * Returns a read-only (constant) reference to the data at the last
193 * element of the %queue.
194 */
195 const_reference
196 back() const
197 {
198 __glibcxx_requires_nonempty();
199 return c.back();
200 }
201
202 /**
203 * @brief Add data to the end of the %queue.
204 * @param __x Data to be added.
205 *
206 * This is a typical %queue operation. The function creates an
207 * element at the end of the %queue and assigns the given data
208 * to it. The time complexity of the operation depends on the
209 * underlying sequence.
210 */
211 void
212 push(const value_type& __x)
213 { c.push_back(__x); }
214
215 #if __cplusplus >= 201103L
216 void
217 push(value_type&& __x)
218 { c.push_back(std::move(__x)); }
219
220 template<typename... _Args>
221 void
222 emplace(_Args&&... __args)
223 { c.emplace_back(std::forward<_Args>(__args)...); }
224 #endif
225
226 /**
227 * @brief Removes first element.
228 *
229 * This is a typical %queue operation. It shrinks the %queue by one.
230 * The time complexity of the operation depends on the underlying
231 * sequence.
232 *
233 * Note that no data is returned, and if the first element's
234 * data is needed, it should be retrieved before pop() is
235 * called.
236 */
237 void
238 pop()
239 {
240 __glibcxx_requires_nonempty();
241 c.pop_front();
242 }
243
244 #if __cplusplus >= 201103L
245 void
246 swap(queue& __q)
247 noexcept(noexcept(swap(c, __q.c)))
248 {
249 using std::swap;
250 swap(c, __q.c);
251 }
252 #endif
253 };
254
255 /**
256 * @brief Queue equality comparison.
257 * @param __x A %queue.
258 * @param __y A %queue of the same type as @a __x.
259 * @return True iff the size and elements of the queues are equal.
260 *
261 * This is an equivalence relation. Complexity and semantics depend on the
262 * underlying sequence type, but the expected rules are: this relation is
263 * linear in the size of the sequences, and queues are considered equivalent
264 * if their sequences compare equal.
265 */
266 template<typename _Tp, typename _Seq>
267 inline bool
268 operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
269 { return __x.c == __y.c; }
270
271 /**
272 * @brief Queue ordering relation.
273 * @param __x A %queue.
274 * @param __y A %queue of the same type as @a x.
275 * @return True iff @a __x is lexicographically less than @a __y.
276 *
277 * This is an total ordering relation. Complexity and semantics
278 * depend on the underlying sequence type, but the expected rules
279 * are: this relation is linear in the size of the sequences, the
280 * elements must be comparable with @c <, and
281 * std::lexicographical_compare() is usually used to make the
282 * determination.
283 */
284 template<typename _Tp, typename _Seq>
285 inline bool
286 operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
287 { return __x.c < __y.c; }
288
289 /// Based on operator==
290 template<typename _Tp, typename _Seq>
291 inline bool
292 operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
293 { return !(__x == __y); }
294
295 /// Based on operator<
296 template<typename _Tp, typename _Seq>
297 inline bool
298 operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
299 { return __y < __x; }
300
301 /// Based on operator<
302 template<typename _Tp, typename _Seq>
303 inline bool
304 operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
305 { return !(__y < __x); }
306
307 /// Based on operator<
308 template<typename _Tp, typename _Seq>
309 inline bool
310 operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
311 { return !(__x < __y); }
312
313 #if __cplusplus >= 201103L
314 template<typename _Tp, typename _Seq>
315 inline void
316 swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
317 noexcept(noexcept(__x.swap(__y)))
318 { __x.swap(__y); }
319
320 template<typename _Tp, typename _Seq, typename _Alloc>
321 struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
322 : public uses_allocator<_Seq, _Alloc>::type { };
323 #endif
324
325 /**
326 * @brief A standard container automatically sorting its contents.
327 *
328 * @ingroup sequences
329 *
330 * @tparam _Tp Type of element.
331 * @tparam _Sequence Type of underlying sequence, defaults to vector<_Tp>.
332 * @tparam _Compare Comparison function object type, defaults to
333 * less<_Sequence::value_type>.
334 *
335 * This is not a true container, but an @e adaptor. It holds
336 * another container, and provides a wrapper interface to that
337 * container. The wrapper is what enforces priority-based sorting
338 * and %queue behavior. Very few of the standard container/sequence
339 * interface requirements are met (e.g., iterators).
340 *
341 * The second template parameter defines the type of the underlying
342 * sequence/container. It defaults to std::vector, but it can be
343 * any type that supports @c front(), @c push_back, @c pop_back,
344 * and random-access iterators, such as std::deque or an
345 * appropriate user-defined type.
346 *
347 * The third template parameter supplies the means of making
348 * priority comparisons. It defaults to @c less<value_type> but
349 * can be anything defining a strict weak ordering.
350 *
351 * Members not found in @a normal containers are @c container_type,
352 * which is a typedef for the second Sequence parameter, and @c
353 * push, @c pop, and @c top, which are standard %queue operations.
354 *
355 * @note No equality/comparison operators are provided for
356 * %priority_queue.
357 *
358 * @note Sorting of the elements takes place as they are added to,
359 * and removed from, the %priority_queue using the
360 * %priority_queue's member functions. If you access the elements
361 * by other means, and change their data such that the sorting
362 * order would be different, the %priority_queue will not re-sort
363 * the elements for you. (How could it know to do so?)
364 */
365 template<typename _Tp, typename _Sequence = vector<_Tp>,
366 typename _Compare = less<typename _Sequence::value_type> >
367 class priority_queue
368 {
369 // concept requirements
370 typedef typename _Sequence::value_type _Sequence_value_type;
371 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
372 __glibcxx_class_requires(_Sequence, _SequenceConcept)
373 __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
374 __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
375 __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
376 _BinaryFunctionConcept)
377
378 public:
379 typedef typename _Sequence::value_type value_type;
380 typedef typename _Sequence::reference reference;
381 typedef typename _Sequence::const_reference const_reference;
382 typedef typename _Sequence::size_type size_type;
383 typedef _Sequence container_type;
384
385 protected:
386 // See queue::c for notes on these names.
387 _Sequence c;
388 _Compare comp;
389
390 public:
391 /**
392 * @brief Default constructor creates no elements.
393 */
394 #if __cplusplus < 201103L
395 explicit
396 priority_queue(const _Compare& __x = _Compare(),
397 const _Sequence& __s = _Sequence())
398 : c(__s), comp(__x)
399 { std::make_heap(c.begin(), c.end(), comp); }
400 #else
401 explicit
402 priority_queue(const _Compare& __x,
403 const _Sequence& __s)
404 : c(__s), comp(__x)
405 { std::make_heap(c.begin(), c.end(), comp); }
406
407 explicit
408 priority_queue(const _Compare& __x = _Compare(),
409 _Sequence&& __s = _Sequence())
410 : c(std::move(__s)), comp(__x)
411 { std::make_heap(c.begin(), c.end(), comp); }
412 #endif
413
414 /**
415 * @brief Builds a %queue from a range.
416 * @param __first An input iterator.
417 * @param __last An input iterator.
418 * @param __x A comparison functor describing a strict weak ordering.
419 * @param __s An initial sequence with which to start.
420 *
421 * Begins by copying @a __s, inserting a copy of the elements
422 * from @a [first,last) into the copy of @a __s, then ordering
423 * the copy according to @a __x.
424 *
425 * For more information on function objects, see the
426 * documentation on @link functors functor base
427 * classes@endlink.
428 */
429 #if __cplusplus < 201103L
430 template<typename _InputIterator>
431 priority_queue(_InputIterator __first, _InputIterator __last,
432 const _Compare& __x = _Compare(),
433 const _Sequence& __s = _Sequence())
434 : c(__s), comp(__x)
435 {
436 __glibcxx_requires_valid_range(__first, __last);
437 c.insert(c.end(), __first, __last);
438 std::make_heap(c.begin(), c.end(), comp);
439 }
440 #else
441 template<typename _InputIterator>
442 priority_queue(_InputIterator __first, _InputIterator __last,
443 const _Compare& __x,
444 const _Sequence& __s)
445 : c(__s), comp(__x)
446 {
447 __glibcxx_requires_valid_range(__first, __last);
448 c.insert(c.end(), __first, __last);
449 std::make_heap(c.begin(), c.end(), comp);
450 }
451
452 template<typename _InputIterator>
453 priority_queue(_InputIterator __first, _InputIterator __last,
454 const _Compare& __x = _Compare(),
455 _Sequence&& __s = _Sequence())
456 : c(std::move(__s)), comp(__x)
457 {
458 __glibcxx_requires_valid_range(__first, __last);
459 c.insert(c.end(), __first, __last);
460 std::make_heap(c.begin(), c.end(), comp);
461 }
462 #endif
463
464 /**
465 * Returns true if the %queue is empty.
466 */
467 bool
468 empty() const
469 { return c.empty(); }
470
471 /** Returns the number of elements in the %queue. */
472 size_type
473 size() const
474 { return c.size(); }
475
476 /**
477 * Returns a read-only (constant) reference to the data at the first
478 * element of the %queue.
479 */
480 const_reference
481 top() const
482 {
483 __glibcxx_requires_nonempty();
484 return c.front();
485 }
486
487 /**
488 * @brief Add data to the %queue.
489 * @param __x Data to be added.
490 *
491 * This is a typical %queue operation.
492 * The time complexity of the operation depends on the underlying
493 * sequence.
494 */
495 void
496 push(const value_type& __x)
497 {
498 c.push_back(__x);
499 std::push_heap(c.begin(), c.end(), comp);
500 }
501
502 #if __cplusplus >= 201103L
503 void
504 push(value_type&& __x)
505 {
506 c.push_back(std::move(__x));
507 std::push_heap(c.begin(), c.end(), comp);
508 }
509
510 template<typename... _Args>
511 void
512 emplace(_Args&&... __args)
513 {
514 c.emplace_back(std::forward<_Args>(__args)...);
515 std::push_heap(c.begin(), c.end(), comp);
516 }
517 #endif
518
519 /**
520 * @brief Removes first element.
521 *
522 * This is a typical %queue operation. It shrinks the %queue
523 * by one. The time complexity of the operation depends on the
524 * underlying sequence.
525 *
526 * Note that no data is returned, and if the first element's
527 * data is needed, it should be retrieved before pop() is
528 * called.
529 */
530 void
531 pop()
532 {
533 __glibcxx_requires_nonempty();
534 std::pop_heap(c.begin(), c.end(), comp);
535 c.pop_back();
536 }
537
538 #if __cplusplus >= 201103L
539 void
540 swap(priority_queue& __pq)
541 noexcept(noexcept(swap(c, __pq.c)) && noexcept(swap(comp, __pq.comp)))
542 {
543 using std::swap;
544 swap(c, __pq.c);
545 swap(comp, __pq.comp);
546 }
547 #endif
548 };
549
550 // No equality/comparison operators are provided for priority_queue.
551
552 #if __cplusplus >= 201103L
553 template<typename _Tp, typename _Sequence, typename _Compare>
554 inline void
555 swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
556 priority_queue<_Tp, _Sequence, _Compare>& __y)
557 noexcept(noexcept(__x.swap(__y)))
558 { __x.swap(__y); }
559
560 template<typename _Tp, typename _Sequence, typename _Compare,
561 typename _Alloc>
562 struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
563 : public uses_allocator<_Sequence, _Alloc>::type { };
564 #endif
565
566 _GLIBCXX_END_NAMESPACE_VERSION
567 } // namespace
568
569 #endif /* _STL_QUEUE_H */