# stl_queue.h

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    00001 // Queue implementation -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006
    00004 // Free Software Foundation, Inc.
    00005 //
    00006 // This file is part of the GNU ISO C++ Library.  This library is free
    00007 // software; you can redistribute it and/or modify it under the
    00008 // terms of the GNU General Public License as published by the
    00009 // Free Software Foundation; either version 2, or (at your option)
    00010 // any later version.
    00011
    00012 // This library is distributed in the hope that it will be useful,
    00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00015 // GNU General Public License for more details.
    00016
    00017 // You should have received a copy of the GNU General Public License along
    00018 // with this library; see the file COPYING.  If not, write to the Free
    00019 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    00020 // USA.
    00021
    00022 // As a special exception, you may use this file as part of a free software
    00023 // library without restriction.  Specifically, if other files instantiate
    00024 // templates or use macros or inline functions from this file, or you compile
    00025 // this file and link it with other files to produce an executable, this
    00026 // file does not by itself cause the resulting executable to be covered by
    00027 // the GNU General Public License.  This exception does not however
    00028 // invalidate any other reasons why the executable file might be covered by
    00029 // the GNU General Public License.
    00030
    00031 /*
    00032  *
    00033  * Copyright (c) 1994
    00034  * Hewlett-Packard Company
    00035  *
    00036  * Permission to use, copy, modify, distribute and sell this software
    00037  * and its documentation for any purpose is hereby granted without fee,
    00038  * provided that the above copyright notice appear in all copies and
    00039  * that both that copyright notice and this permission notice appear
    00040  * in supporting documentation.  Hewlett-Packard Company makes no
    00041  * representations about the suitability of this software for any
    00042  * purpose.  It is provided "as is" without express or implied warranty.
    00043  *
    00044  *
    00045  * Copyright (c) 1996,1997
    00046  * Silicon Graphics Computer Systems, Inc.
    00047  *
    00048  * Permission to use, copy, modify, distribute and sell this software
    00049  * and its documentation for any purpose is hereby granted without fee,
    00050  * provided that the above copyright notice appear in all copies and
    00051  * that both that copyright notice and this permission notice appear
    00052  * in supporting documentation.  Silicon Graphics makes no
    00053  * representations about the suitability of this software for any
    00054  * purpose.  It is provided "as is" without express or implied warranty.
    00055  */
    00056
    00057 /** @file stl_queue.h
    00058  *  This is an internal header file, included by other library headers.
    00059  *  You should not attempt to use it directly.
    00060  */
    00061
    00062 #ifndef _QUEUE_H
    00063 #define _QUEUE_H 1
    00064
    00065 #include <bits/concept_check.h>
    00066 #include <debug/debug.h>
    00067
    00068 _GLIBCXX_BEGIN_NAMESPACE(std)
    00069
    00070   /**
    00071    *  @brief  A standard container giving FIFO behavior.
    00072    *
    00073    *  @ingroup Containers
    00074    *  @ingroup Sequences
    00075    *
    00076    *  Meets many of the requirements of a
    00077    *  <a href="tables.html#65">container</a>,
    00078    *  but does not define anything to do with iterators.  Very few of the
    00079    *  other standard container interfaces are defined.
    00080    *
    00081    *  This is not a true container, but an @e adaptor.  It holds another
    00082    *  container, and provides a wrapper interface to that container.  The
    00083    *  wrapper is what enforces strict first-in-first-out %queue behavior.
    00084    *
    00085    *  The second template parameter defines the type of the underlying
    00086    *  sequence/container.  It defaults to std::deque, but it can be any type
    00087    *  that supports @c front, @c back, @c push_back, and @c pop_front,
    00088    *  such as std::list or an appropriate user-defined type.
    00089    *
    00090    *  Members not found in "normal" containers are @c container_type,
    00091    *  which is a typedef for the second Sequence parameter, and @c push and
    00092    *  @c pop, which are standard %queue/FIFO operations.
    00093   */
    00094   template<typename _Tp, typename _Sequence = deque<_Tp> >
    00095     class queue
    00096     {
    00097       // concept requirements
    00098       typedef typename _Sequence::value_type _Sequence_value_type;
    00099       __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
    00100       __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)
    00101       __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)
    00102       __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
    00103
    00104       template<typename _Tp1, typename _Seq1>
    00105         friend bool
    00106         operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
    00107
    00108       template<typename _Tp1, typename _Seq1>
    00109         friend bool
    00110         operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);
    00111
    00112     public:
    00113       typedef typename _Sequence::value_type                value_type;
    00114       typedef typename _Sequence::reference                 reference;
    00115       typedef typename _Sequence::const_reference           const_reference;
    00116       typedef typename _Sequence::size_type                 size_type;
    00117       typedef          _Sequence                            container_type;
    00118
    00119     protected:
    00120       /**
    00121        *  'c' is the underlying container.  Maintainers wondering why
    00122        *  this isn't uglified as per style guidelines should note that
    00123        *  this name is specified in the standard, [23.2.3.1].  (Why?
    00124        *  Presumably for the same reason that it's protected instead
    00125        *  of private: to allow derivation.  But none of the other
    00126        *  containers allow for derivation.  Odd.)
    00127        */
    00128       _Sequence c;
    00129
    00130     public:
    00131       /**
    00132        *  @brief  Default constructor creates no elements.
    00133        */
    00134       explicit
    00135       queue(const _Sequence& __c = _Sequence()) : c(__c) {}
    00136
    00137       /**
    00138        *  Returns true if the %queue is empty.
    00139        */
    00140       bool
    00141       empty() const
    00142       { return c.empty(); }
    00143
    00144       /**  Returns the number of elements in the %queue.  */
    00145       size_type
    00146       size() const
    00147       { return c.size(); }
    00148
    00149       /**
    00150        *  Returns a read/write reference to the data at the first
    00151        *  element of the %queue.
    00152        */
    00153       reference
    00154       front()
    00155       {
    00156     __glibcxx_requires_nonempty();
    00157     return c.front();
    00158       }
    00159
    00160       /**
    00161        *  Returns a read-only (constant) reference to the data at the first
    00162        *  element of the %queue.
    00163        */
    00164       const_reference
    00165       front() const
    00166       {
    00167     __glibcxx_requires_nonempty();
    00168     return c.front();
    00169       }
    00170
    00171       /**
    00172        *  Returns a read/write reference to the data at the last
    00173        *  element of the %queue.
    00174        */
    00175       reference
    00176       back()
    00177       {
    00178     __glibcxx_requires_nonempty();
    00179     return c.back();
    00180       }
    00181
    00182       /**
    00183        *  Returns a read-only (constant) reference to the data at the last
    00184        *  element of the %queue.
    00185        */
    00186       const_reference
    00187       back() const
    00188       {
    00189     __glibcxx_requires_nonempty();
    00190     return c.back();
    00191       }
    00192
    00193       /**
    00194        *  @brief  Add data to the end of the %queue.
    00195        *  @param  x  Data to be added.
    00196        *
    00197        *  This is a typical %queue operation.  The function creates an
    00198        *  element at the end of the %queue and assigns the given data
    00199        *  to it.  The time complexity of the operation depends on the
    00200        *  underlying sequence.
    00201        */
    00202       void
    00203       push(const value_type& __x)
    00204       { c.push_back(__x); }
    00205
    00206       /**
    00207        *  @brief  Removes first element.
    00208        *
    00209        *  This is a typical %queue operation.  It shrinks the %queue by one.
    00210        *  The time complexity of the operation depends on the underlying
    00211        *  sequence.
    00212        *
    00213        *  Note that no data is returned, and if the first element's
    00214        *  data is needed, it should be retrieved before pop() is
    00215        *  called.
    00216        */
    00217       void
    00218       pop()
    00219       {
    00220     __glibcxx_requires_nonempty();
    00221     c.pop_front();
    00222       }
    00223     };
    00224
    00225
    00226   /**
    00227    *  @brief  Queue equality comparison.
    00228    *  @param  x  A %queue.
    00229    *  @param  y  A %queue of the same type as @a x.
    00230    *  @return  True iff the size and elements of the queues are equal.
    00231    *
    00232    *  This is an equivalence relation.  Complexity and semantics depend on the
    00233    *  underlying sequence type, but the expected rules are:  this relation is
    00234    *  linear in the size of the sequences, and queues are considered equivalent
    00235    *  if their sequences compare equal.
    00236   */
    00237   template<typename _Tp, typename _Seq>
    00238     inline bool
    00239     operator==(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00240     { return __x.c == __y.c; }
    00241
    00242   /**
    00243    *  @brief  Queue ordering relation.
    00244    *  @param  x  A %queue.
    00245    *  @param  y  A %queue of the same type as @a x.
    00246    *  @return  True iff @a x is lexicographically less than @a y.
    00247    *
    00248    *  This is an total ordering relation.  Complexity and semantics
    00249    *  depend on the underlying sequence type, but the expected rules
    00250    *  are: this relation is linear in the size of the sequences, the
    00251    *  elements must be comparable with @c <, and
    00252    *  std::lexicographical_compare() is usually used to make the
    00253    *  determination.
    00254   */
    00255   template<typename _Tp, typename _Seq>
    00256     inline bool
    00257     operator<(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00258     { return __x.c < __y.c; }
    00259
    00260   /// Based on operator==
    00261   template<typename _Tp, typename _Seq>
    00262     inline bool
    00263     operator!=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00264     { return !(__x == __y); }
    00265
    00266   /// Based on operator<
    00267   template<typename _Tp, typename _Seq>
    00268     inline bool
    00269     operator>(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00270     { return __y < __x; }
    00271
    00272   /// Based on operator<
    00273   template<typename _Tp, typename _Seq>
    00274     inline bool
    00275     operator<=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00276     { return !(__y < __x); }
    00277
    00278   /// Based on operator<
    00279   template<typename _Tp, typename _Seq>
    00280     inline bool
    00281     operator>=(const queue<_Tp, _Seq>& __x, const queue<_Tp, _Seq>& __y)
    00282     { return !(__x < __y); }
    00283
    00284   /**
    00285    *  @brief  A standard container automatically sorting its contents.
    00286    *
    00287    *  @ingroup Containers
    00288    *  @ingroup Sequences
    00289    *
    00290    *  This is not a true container, but an @e adaptor.  It holds
    00291    *  another container, and provides a wrapper interface to that
    00292    *  container.  The wrapper is what enforces priority-based sorting
    00293    *  and %queue behavior.  Very few of the standard container/sequence
    00294    *  interface requirements are met (e.g., iterators).
    00295    *
    00296    *  The second template parameter defines the type of the underlying
    00297    *  sequence/container.  It defaults to std::vector, but it can be
    00298    *  any type that supports @c front(), @c push_back, @c pop_back,
    00299    *  and random-access iterators, such as std::deque or an
    00300    *  appropriate user-defined type.
    00301    *
    00302    *  The third template parameter supplies the means of making
    00303    *  priority comparisons.  It defaults to @c less<value_type> but
    00304    *  can be anything defining a strict weak ordering.
    00305    *
    00306    *  Members not found in "normal" containers are @c container_type,
    00307    *  which is a typedef for the second Sequence parameter, and @c
    00308    *  push, @c pop, and @c top, which are standard %queue operations.
    00309    *
    00310    *  @note No equality/comparison operators are provided for
    00311    *  %priority_queue.
    00312    *
    00313    *  @note Sorting of the elements takes place as they are added to,
    00314    *  and removed from, the %priority_queue using the
    00315    *  %priority_queue's member functions.  If you access the elements
    00316    *  by other means, and change their data such that the sorting
    00317    *  order would be different, the %priority_queue will not re-sort
    00318    *  the elements for you.  (How could it know to do so?)
    00319   */
    00320   template<typename _Tp, typename _Sequence = vector<_Tp>,
    00321        typename _Compare  = less<typename _Sequence::value_type> >
    00322     class priority_queue
    00323     {
    00324       // concept requirements
    00325       typedef typename _Sequence::value_type _Sequence_value_type;
    00326       __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
    00327       __glibcxx_class_requires(_Sequence, _SequenceConcept)
    00328       __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)
    00329       __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)
    00330       __glibcxx_class_requires4(_Compare, bool, _Tp, _Tp,
    00331                 _BinaryFunctionConcept)
    00332
    00333     public:
    00334       typedef typename _Sequence::value_type                value_type;
    00335       typedef typename _Sequence::reference                 reference;
    00336       typedef typename _Sequence::const_reference           const_reference;
    00337       typedef typename _Sequence::size_type                 size_type;
    00338       typedef          _Sequence                            container_type;
    00339
    00340     protected:
    00341       //  See queue::c for notes on these names.
    00342       _Sequence  c;
    00343       _Compare   comp;
    00344
    00345     public:
    00346       /**
    00347        *  @brief  Default constructor creates no elements.
    00348        */
    00349       explicit
    00350       priority_queue(const _Compare& __x = _Compare(),
    00351              const _Sequence& __s = _Sequence())
    00352       : c(__s), comp(__x)
    00353       { std::make_heap(c.begin(), c.end(), comp); }
    00354
    00355       /**
    00356        *  @brief  Builds a %queue from a range.
    00357        *  @param  first  An input iterator.
    00358        *  @param  last  An input iterator.
    00359        *  @param  x  A comparison functor describing a strict weak ordering.
    00360        *  @param  s  An initial sequence with which to start.
    00361        *
    00362        *  Begins by copying @a s, inserting a copy of the elements
    00363        *  from @a [first,last) into the copy of @a s, then ordering
    00364        *  the copy according to @a x.
    00365        *
    00366        *  For more information on function objects, see the
    00367        *  documentation on @link s20_3_1_base functor base
    00368        *  classes@endlink.
    00369        */
    00370       template<typename _InputIterator>
    00371         priority_queue(_InputIterator __first, _InputIterator __last,
    00372                const _Compare& __x = _Compare(),
    00373                const _Sequence& __s = _Sequence())
    00374     : c(__s), comp(__x)
    00375         {
    00376       __glibcxx_requires_valid_range(__first, __last);
    00377       c.insert(c.end(), __first, __last);
    00378       std::make_heap(c.begin(), c.end(), comp);
    00379     }
    00380
    00381       /**
    00382        *  Returns true if the %queue is empty.
    00383        */
    00384       bool
    00385       empty() const
    00386       { return c.empty(); }
    00387
    00388       /**  Returns the number of elements in the %queue.  */
    00389       size_type
    00390       size() const
    00391       { return c.size(); }
    00392
    00393       /**
    00394        *  Returns a read-only (constant) reference to the data at the first
    00395        *  element of the %queue.
    00396        */
    00397       const_reference
    00398       top() const
    00399       {
    00400     __glibcxx_requires_nonempty();
    00401     return c.front();
    00402       }
    00403
    00404       /**
    00405        *  @brief  Add data to the %queue.
    00406        *  @param  x  Data to be added.
    00407        *
    00408        *  This is a typical %queue operation.
    00409        *  The time complexity of the operation depends on the underlying
    00410        *  sequence.
    00411        */
    00412       void
    00413       push(const value_type& __x)
    00414       {
    00415     c.push_back(__x);
    00416     std::push_heap(c.begin(), c.end(), comp);
    00417       }
    00418
    00419       /**
    00420        *  @brief  Removes first element.
    00421        *
    00422        *  This is a typical %queue operation.  It shrinks the %queue
    00423        *  by one.  The time complexity of the operation depends on the
    00424        *  underlying sequence.
    00425        *
    00426        *  Note that no data is returned, and if the first element's
    00427        *  data is needed, it should be retrieved before pop() is
    00428        *  called.
    00429        */
    00430       void
    00431       pop()
    00432       {
    00433     __glibcxx_requires_nonempty();
    00434     std::pop_heap(c.begin(), c.end(), comp);
    00435     c.pop_back();
    00436       }
    00437     };
    00438
    00439   // No equality/comparison operators are provided for priority_queue.
    00440
    00441 _GLIBCXX_END_NAMESPACE
    00442
    00443 #endif /* _QUEUE_H */