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 */

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