libstdc++
stl_queue.h
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1 // Queue implementation -*- C++ -*-
2 
3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 // 2010, 2011
5 // Free Software Foundation, Inc.
6 //
7 // This file is part of the GNU ISO C++ Library. This library is free
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9 // terms of the GNU General Public License as published by the
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12 
13 // This library is distributed in the hope that it will be useful,
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15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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17 
18 // Under Section 7 of GPL version 3, you are granted additional
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20 // 3.1, as published by the Free Software Foundation.
21 
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26 
27 /*
28  *
29  * Copyright (c) 1994
30  * Hewlett-Packard Company
31  *
32  * Permission to use, copy, modify, distribute and sell this software
33  * and its documentation for any purpose is hereby granted without fee,
34  * provided that the above copyright notice appear in all copies and
35  * that both that copyright notice and this permission notice appear
36  * in supporting documentation. Hewlett-Packard Company makes no
37  * representations about the suitability of this software for any
38  * purpose. It is provided "as is" without express or implied warranty.
39  *
40  *
41  * Copyright (c) 1996,1997
42  * Silicon Graphics Computer Systems, Inc.
43  *
44  * Permission to use, copy, modify, distribute and sell this software
45  * and its documentation for any purpose is hereby granted without fee,
46  * provided that the above copyright notice appear in all copies and
47  * that both that copyright notice and this permission notice appear
48  * in supporting documentation. Silicon Graphics makes no
49  * representations about the suitability of this software for any
50  * purpose. It is provided "as is" without express or implied warranty.
51  */
52 
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}
56  */
57 
58 #ifndef _STL_QUEUE_H
59 #define _STL_QUEUE_H 1
60 
61 #include <bits/concept_check.h>
62 #include <debug/debug.h>
63 
64 namespace std _GLIBCXX_VISIBILITY(default)
65 {
66 _GLIBCXX_BEGIN_NAMESPACE_VERSION
67 
68  /**
69  * @brief A standard container giving FIFO behavior.
70  *
71  * @ingroup sequences
72  *
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.
77  *
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.
81  *
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.
86  *
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.
90  */
91  template<typename _Tp, typename _Sequence = deque<_Tp> >
92  class queue
93  {
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)
100 
101  template<typename _Tp1, typename _Seq1>
102  friend bool
103  operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
104 
105  template<typename _Tp1, typename _Seq1>
106  friend bool
107  operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
108 
109  public:
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;
115 
116  protected:
117  /**
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.)
124  */
125  _Sequence c;
126 
127  public:
128  /**
129  * @brief Default constructor creates no elements.
130  */
131 #ifndef __GXX_EXPERIMENTAL_CXX0X__
132  explicit
133  queue(const _Sequence& __c = _Sequence())
134  : c(__c) { }
135 #else
136  explicit
137  queue(const _Sequence& __c)
138  : c(__c) { }
139 
140  explicit
141  queue(_Sequence&& __c = _Sequence())
142  : c(std::move(__c)) { }
143 #endif
144 
145  /**
146  * Returns true if the %queue is empty.
147  */
148  bool
149  empty() const
150  { return c.empty(); }
151 
152  /** Returns the number of elements in the %queue. */
153  size_type
154  size() const
155  { return c.size(); }
156 
157  /**
158  * Returns a read/write reference to the data at the first
159  * element of the %queue.
160  */
161  reference
163  {
164  __glibcxx_requires_nonempty();
165  return c.front();
166  }
167 
168  /**
169  * Returns a read-only (constant) reference to the data at the first
170  * element of the %queue.
171  */
172  const_reference
173  front() const
174  {
175  __glibcxx_requires_nonempty();
176  return c.front();
177  }
178 
179  /**
180  * Returns a read/write reference to the data at the last
181  * element of the %queue.
182  */
183  reference
185  {
186  __glibcxx_requires_nonempty();
187  return c.back();
188  }
189 
190  /**
191  * Returns a read-only (constant) reference to the data at the last
192  * element of the %queue.
193  */
194  const_reference
195  back() const
196  {
197  __glibcxx_requires_nonempty();
198  return c.back();
199  }
200 
201  /**
202  * @brief Add data to the end of the %queue.
203  * @param __x Data to be added.
204  *
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.
209  */
210  void
211  push(const value_type& __x)
212  { c.push_back(__x); }
213 
214 #ifdef __GXX_EXPERIMENTAL_CXX0X__
215  void
216  push(value_type&& __x)
217  { c.push_back(std::move(__x)); }
218 
219  template<typename... _Args>
220  void
221  emplace(_Args&&... __args)
222  { c.emplace_back(std::forward<_Args>(__args)...); }
223 #endif
224 
225  /**
226  * @brief Removes first element.
227  *
228  * This is a typical %queue operation. It shrinks the %queue by one.
229  * The time complexity of the operation depends on the underlying
230  * sequence.
231  *
232  * Note that no data is returned, and if the first element's
233  * data is needed, it should be retrieved before pop() is
234  * called.
235  */
236  void
237  pop()
238  {
239  __glibcxx_requires_nonempty();
240  c.pop_front();
241  }
242 
243 #ifdef __GXX_EXPERIMENTAL_CXX0X__
244  void
245  swap(queue& __q)
246  noexcept(noexcept(swap(c, __q.c)))
247  {
248  using std::swap;
249  swap(c, __q.c);
250  }
251 #endif
252  };
253 
254  /**
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.
259  *
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.
264  */
265  template<typename _Tp, typename _Seq>
266  inline bool
267  operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
268  { return __x.c == __y.c; }
269 
270  /**
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.
275  *
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
281  * determination.
282  */
283  template<typename _Tp, typename _Seq>
284  inline bool
285  operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
286  { return __x.c < __y.c; }
287 
288  /// Based on operator==
289  template<typename _Tp, typename _Seq>
290  inline bool
291  operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
292  { return !(__x == __y); }
293 
294  /// Based on operator<
295  template<typename _Tp, typename _Seq>
296  inline bool
297  operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
298  { return __y < __x; }
299 
300  /// Based on operator<
301  template<typename _Tp, typename _Seq>
302  inline bool
303  operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
304  { return !(__y < __x); }
305 
306  /// Based on operator<
307  template<typename _Tp, typename _Seq>
308  inline bool
309  operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
310  { return !(__x < __y); }
311 
312 #ifdef __GXX_EXPERIMENTAL_CXX0X__
313  template<typename _Tp, typename _Seq>
314  inline void
315  swap(queue<_Tp, _Seq>& __x, queue<_Tp, _Seq>& __y)
316  noexcept(noexcept(__x.swap(__y)))
317  { __x.swap(__y); }
318 
319  template<typename _Tp, typename _Seq, typename _Alloc>
320  struct uses_allocator<queue<_Tp, _Seq>, _Alloc>
321  : public uses_allocator<_Seq, _Alloc>::type { };
322 #endif
323 
324  /**
325  * @brief A standard container automatically sorting its contents.
326  *
327  * @ingroup sequences
328  *
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).
334  *
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.
340  *
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.
344  *
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.
348  *
349  * @note No equality/comparison operators are provided for
350  * %priority_queue.
351  *
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?)
358  */
359  template<typename _Tp, typename _Sequence = vector<_Tp>,
360  typename _Compare = less<typename _Sequence::value_type> >
362  {
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)
371 
372  public:
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;
378 
379  protected:
380  // See queue::c for notes on these names.
381  _Sequence c;
382  _Compare comp;
383 
384  public:
385  /**
386  * @brief Default constructor creates no elements.
387  */
388 #ifndef __GXX_EXPERIMENTAL_CXX0X__
389  explicit
390  priority_queue(const _Compare& __x = _Compare(),
391  const _Sequence& __s = _Sequence())
392  : c(__s), comp(__x)
393  { std::make_heap(c.begin(), c.end(), comp); }
394 #else
395  explicit
396  priority_queue(const _Compare& __x,
397  const _Sequence& __s)
398  : c(__s), comp(__x)
399  { std::make_heap(c.begin(), c.end(), comp); }
400 
401  explicit
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); }
406 #endif
407 
408  /**
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.
414  *
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.
418  *
419  * For more information on function objects, see the
420  * documentation on @link functors functor base
421  * classes@endlink.
422  */
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())
428  : c(__s), comp(__x)
429  {
430  __glibcxx_requires_valid_range(__first, __last);
431  c.insert(c.end(), __first, __last);
432  std::make_heap(c.begin(), c.end(), comp);
433  }
434 #else
435  template<typename _InputIterator>
436  priority_queue(_InputIterator __first, _InputIterator __last,
437  const _Compare& __x,
438  const _Sequence& __s)
439  : c(__s), comp(__x)
440  {
441  __glibcxx_requires_valid_range(__first, __last);
442  c.insert(c.end(), __first, __last);
443  std::make_heap(c.begin(), c.end(), comp);
444  }
445 
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)
451  {
452  __glibcxx_requires_valid_range(__first, __last);
453  c.insert(c.end(), __first, __last);
454  std::make_heap(c.begin(), c.end(), comp);
455  }
456 #endif
457 
458  /**
459  * Returns true if the %queue is empty.
460  */
461  bool
462  empty() const
463  { return c.empty(); }
464 
465  /** Returns the number of elements in the %queue. */
466  size_type
467  size() const
468  { return c.size(); }
469 
470  /**
471  * Returns a read-only (constant) reference to the data at the first
472  * element of the %queue.
473  */
474  const_reference
475  top() const
476  {
477  __glibcxx_requires_nonempty();
478  return c.front();
479  }
480 
481  /**
482  * @brief Add data to the %queue.
483  * @param __x Data to be added.
484  *
485  * This is a typical %queue operation.
486  * The time complexity of the operation depends on the underlying
487  * sequence.
488  */
489  void
490  push(const value_type& __x)
491  {
492  c.push_back(__x);
493  std::push_heap(c.begin(), c.end(), comp);
494  }
495 
496 #ifdef __GXX_EXPERIMENTAL_CXX0X__
497  void
498  push(value_type&& __x)
499  {
500  c.push_back(std::move(__x));
501  std::push_heap(c.begin(), c.end(), comp);
502  }
503 
504  template<typename... _Args>
505  void
506  emplace(_Args&&... __args)
507  {
508  c.emplace_back(std::forward<_Args>(__args)...);
509  std::push_heap(c.begin(), c.end(), comp);
510  }
511 #endif
512 
513  /**
514  * @brief Removes first element.
515  *
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.
519  *
520  * Note that no data is returned, and if the first element's
521  * data is needed, it should be retrieved before pop() is
522  * called.
523  */
524  void
525  pop()
526  {
527  __glibcxx_requires_nonempty();
528  std::pop_heap(c.begin(), c.end(), comp);
529  c.pop_back();
530  }
531 
532 #ifdef __GXX_EXPERIMENTAL_CXX0X__
533  void
534  swap(priority_queue& __pq)
535  noexcept(noexcept(swap(c, __pq.c)) && noexcept(swap(comp, __pq.comp)))
536  {
537  using std::swap;
538  swap(c, __pq.c);
539  swap(comp, __pq.comp);
540  }
541 #endif
542  };
543 
544  // No equality/comparison operators are provided for priority_queue.
545 
546 #ifdef __GXX_EXPERIMENTAL_CXX0X__
547  template<typename _Tp, typename _Sequence, typename _Compare>
548  inline void
549  swap(priority_queue<_Tp, _Sequence, _Compare>& __x,
550  priority_queue<_Tp, _Sequence, _Compare>& __y)
551  noexcept(noexcept(__x.swap(__y)))
552  { __x.swap(__y); }
553 
554  template<typename _Tp, typename _Sequence, typename _Compare,
555  typename _Alloc>
556  struct uses_allocator<priority_queue<_Tp, _Sequence, _Compare>, _Alloc>
557  : public uses_allocator<_Sequence, _Alloc>::type { };
558 #endif
559 
560 _GLIBCXX_END_NAMESPACE_VERSION
561 } // namespace
562 
563 #endif /* _STL_QUEUE_H */