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// Queue implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library is free

// software; you can redistribute it and/or modify it under the

// terms of the GNU General Public License as published by the

// Free Software Foundation; either version 2, or (at your option)

// any later version.

// This library is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996,1997

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/** @file stl_queue.h

 *  This is an internal header file, included by other library headers.

 *  You should not attempt to use it directly.

 */

#ifndef _QUEUE_H

#define _QUEUE_H 1

#include <bits/concept_check.h>

#include <debug/debug.h>

namespace std

{

  // Forward declarations of operators < and ==, needed for friend declaration.

  template<typename _Tp, typename _Sequence = deque<_Tp> >

    class queue;

  template<typename _Tp, typename _Seq>

    inline bool

    operator==(const queue<_Tp,_Seq>&, const queue<_Tp,_Seq>&);

  template<typename _Tp, typename _Seq>

    inline bool

    operator<(const queue<_Tp,_Seq>&, const queue<_Tp,_Seq>&);

  /**

   *  @brief  A standard container giving FIFO behavior.

   *

   *  @ingroup Containers

   *  @ingroup Sequences

   *

   *  Meets many of the requirements of a

   *  <a href="tables.html#65">container</a>,

   *  but does not define anything to do with iterators.  Very few of the

   *  other standard container interfaces are defined.

   *

   *  This is not a true container, but an @e adaptor.  It holds another

   *  container, and provides a wrapper interface to that container.  The

   *  wrapper is what enforces strict first-in-first-out %queue behavior.

   *

   *  The second template parameter defines the type of the underlying

   *  sequence/container.  It defaults to std::deque, but it can be any type

   *  that supports @c front, @c back, @c push_back, and @c pop_front,

   *  such as std::list or an appropriate user-defined type.

   *

   *  Members not found in "normal" containers are @c container_type,

   *  which is a typedef for the second Sequence parameter, and @c push and

   *  @c pop, which are standard %queue/FIFO operations.

  */

  template<typename _Tp, typename _Sequence>

    class queue

    {

      // concept requirements

      typedef typename _Sequence::value_type _Sequence_value_type;

      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)

      __glibcxx_class_requires(_Sequence, _FrontInsertionSequenceConcept)

      __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)

      __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)

      template<typename _Tp1, typename _Seq1>

        friend bool

        operator==(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);

      template<typename _Tp1, typename _Seq1>

        friend bool

        operator<(const queue<_Tp1, _Seq1>&, const queue<_Tp1, _Seq1>&);

    public:

      typedef typename _Sequence::value_type                value_type;

      typedef typename _Sequence::reference                 reference;

      typedef typename _Sequence::const_reference           const_reference;

      typedef typename _Sequence::size_type                 size_type;

      typedef          _Sequence                            container_type;

    protected:

      /**

       *  'c' is the underlying container.  Maintainers wondering why

       *  this isn't uglified as per style guidelines should note that

       *  this name is specified in the standard, [23.2.3.1].  (Why?

       *  Presumably for the same reason that it's protected instead

       *  of private: to allow derivation.  But none of the other

       *  containers allow for derivation.  Odd.)

       */

      _Sequence c;

    public:

      /**

       *  @brief  Default constructor creates no elements.

       */

      explicit

      queue(const _Sequence& __c = _Sequence()) : c(__c) {}

      /**

       *  Returns true if the %queue is empty.

       */

      bool

      empty() const

      { return c.empty(); }

      /**  Returns the number of elements in the %queue.  */

      size_type

      size() const

      { return c.size(); }

      /**

       *  Returns a read/write reference to the data at the first

       *  element of the %queue.

       */

      reference

      front()

      {

        __glibcxx_requires_nonempty();

        return c.front();

      }

      /**

       *  Returns a read-only (constant) reference to the data at the first

       *  element of the %queue.

       */

      const_reference

      front() const

      {

        __glibcxx_requires_nonempty();

        return c.front();

      }

      /**

       *  Returns a read/write reference to the data at the last

       *  element of the %queue.

       */

      reference

      back()

      {

        __glibcxx_requires_nonempty();

        return c.back();

      }

      /**

       *  Returns a read-only (constant) reference to the data at the last

       *  element of the %queue.

       */

      const_reference

      back() const

      {

        __glibcxx_requires_nonempty();

        return c.back();

      }

      /**

       *  @brief  Add data to the end of the %queue.

       *  @param  x  Data to be added.

       *

       *  This is a typical %queue operation.  The function creates an

       *  element at the end of the %queue and assigns the given data

       *  to it.  The time complexity of the operation depends on the

       *  underlying sequence.

       */

      void

      push(const value_type& __x)

      { c.push_back(__x); }

      /**

       *  @brief  Removes first element.

       *

       *  This is a typical %queue operation.  It shrinks the %queue by one.

       *  The time complexity of the operation depends on the underlying

       *  sequence.

       *

       *  Note that no data is returned, and if the first element's

       *  data is needed, it should be retrieved before pop() is

       *  called.

       */

      void

      pop()

      {

        __glibcxx_requires_nonempty();

        c.pop_front();

      }

    };

  /**

   *  @brief  Queue equality comparison.

   *  @param  x  A %queue.

   *  @param  y  A %queue of the same type as @a x.

   *  @return  True iff the size and elements of the queues are equal.

   *

   *  This is an equivalence relation.  Complexity and semantics depend on the

   *  underlying sequence type, but the expected rules are:  this relation is

   *  linear in the size of the sequences, and queues are considered equivalent

   *  if their sequences compare equal.

  */

  template<typename _Tp, typename _Sequence>

    inline bool

    operator==(const queue<_Tp,_Sequence>& __x,

               const queue<_Tp,_Sequence>& __y)

    { return __x.c == __y.c; }

  /**

   *  @brief  Queue ordering relation.

   *  @param  x  A %queue.

   *  @param  y  A %queue of the same type as @a x.

   *  @return  True iff @a x is lexicographically less than @a y.

   *

   *  This is an total ordering relation.  Complexity and semantics

   *  depend on the underlying sequence type, but the expected rules

   *  are: this relation is linear in the size of the sequences, the

   *  elements must be comparable with @c <, and

   *  std::lexicographical_compare() is usually used to make the

   *  determination.

  */

  template<typename _Tp, typename _Sequence>

    inline bool

    operator<(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y)

    { return __x.c < __y.c; }

  /// Based on operator==

  template<typename _Tp, typename _Sequence>

    inline bool

    operator!=(const queue<_Tp,_Sequence>& __x,

               const queue<_Tp,_Sequence>& __y)

    { return !(__x == __y); }

  /// Based on operator<

  template<typename _Tp, typename _Sequence>

    inline bool

    operator>(const queue<_Tp,_Sequence>& __x, const queue<_Tp,_Sequence>& __y)

    { return __y < __x; }

  /// Based on operator<

  template<typename _Tp, typename _Sequence>

    inline bool

    operator<=(const queue<_Tp,_Sequence>& __x,

               const queue<_Tp,_Sequence>& __y)

    { return !(__y < __x); }

  /// Based on operator<

  template<typename _Tp, typename _Sequence>

    inline bool

    operator>=(const queue<_Tp,_Sequence>& __x,

               const queue<_Tp,_Sequence>& __y)

    { return !(__x < __y); }

  /**

   *  @brief  A standard container automatically sorting its contents.

   *

   *  @ingroup Containers

   *  @ingroup Sequences

   *

   *  This is not a true container, but an @e adaptor.  It holds

   *  another container, and provides a wrapper interface to that

   *  container.  The wrapper is what enforces priority-based sorting

   *  and %queue behavior.  Very few of the standard container/sequence

   *  interface requirements are met (e.g., iterators).

   *

   *  The second template parameter defines the type of the underlying

   *  sequence/container.  It defaults to std::vector, but it can be

   *  any type that supports @c front(), @c push_back, @c pop_back,

   *  and random-access iterators, such as std::deque or an

   *  appropriate user-defined type.

   *

   *  The third template parameter supplies the means of making

   *  priority comparisons.  It defaults to @c less<value_type> but

   *  can be anything defining a strict weak ordering.

   *

   *  Members not found in "normal" containers are @c container_type,

   *  which is a typedef for the second Sequence parameter, and @c

   *  push, @c pop, and @c top, which are standard %queue operations.

   *

   *  @note No equality/comparison operators are provided for

   *  %priority_queue.

   *

   *  @note Sorting of the elements takes place as they are added to,

   *  and removed from, the %priority_queue using the

   *  %priority_queue's member functions.  If you access the elements

   *  by other means, and change their data such that the sorting

   *  order would be different, the %priority_queue will not re-sort

   *  the elements for you.  (How could it know to do so?)

  */

  template<typename _Tp, typename _Sequence = vector<_Tp>,

           typename _Compare  = less<typename _Sequence::value_type> >

    class priority_queue

    {

      // concept requirements

      typedef typename _Sequence::value_type _Sequence_value_type;

      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)

      __glibcxx_class_requires(_Sequence, _SequenceConcept)

      __glibcxx_class_requires(_Sequence, _RandomAccessContainerConcept)

      __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)

      __glibcxx_class_requires4(_Compare, bool, _Tp,_Tp,_BinaryFunctionConcept)

    public:

      typedef typename _Sequence::value_type                value_type;

      typedef typename _Sequence::reference                 reference;

      typedef typename _Sequence::const_reference           const_reference;

      typedef typename _Sequence::size_type                 size_type;

      typedef          _Sequence                            container_type;

    protected:

      //  See queue::c for notes on these names.

      _Sequence  c;

      _Compare   comp;

    public:

      /**

       *  @brief  Default constructor creates no elements.

       */

      explicit

      priority_queue(const _Compare& __x = _Compare(),

                     const _Sequence& __s = _Sequence())

      : c(__s), comp(__x)

      { std::make_heap(c.begin(), c.end(), comp); }

      /**

       *  @brief  Builds a %queue from a range.

       *  @param  first  An input iterator.

       *  @param  last  An input iterator.

       *  @param  x  A comparison functor describing a strict weak ordering.

       *  @param  s  An initial sequence with which to start.

       *

       *  Begins by copying @a s, inserting a copy of the elements

       *  from @a [first,last) into the copy of @a s, then ordering

       *  the copy according to @a x.

       *

       *  For more information on function objects, see the

       *  documentation on @link s20_3_1_base functor base

       *  classes@endlink.

       */

      template<typename _InputIterator>

        priority_queue(_InputIterator __first, _InputIterator __last,

                       const _Compare& __x = _Compare(),

                       const _Sequence& __s = _Sequence())

        : c(__s), comp(__x)

        {

          __glibcxx_requires_valid_range(__first, __last);

          c.insert(c.end(), __first, __last);

          std::make_heap(c.begin(), c.end(), comp);

        }

      /**

       *  Returns true if the %queue is empty.

       */

      bool

      empty() const { return c.empty(); }

      /**  Returns the number of elements in the %queue.  */

      size_type

      size() const { return c.size(); }

      /**

       *  Returns a read-only (constant) reference to the data at the first

       *  element of the %queue.

       */

      const_reference

      top() const

      {

        __glibcxx_requires_nonempty();

        return c.front();

      }

      /**

       *  @brief  Add data to the %queue.

       *  @param  x  Data to be added.

       *

       *  This is a typical %queue operation.

       *  The time complexity of the operation depends on the underlying

       *  sequence.

       */

      void

      push(const value_type& __x)

      {

        try

        {

          c.push_back(__x);

          std::push_heap(c.begin(), c.end(), comp);

        }

        catch(...)

        {

          c.clear();

          __throw_exception_again;

        }

      }

      /**

       *  @brief  Removes first element.

       *

       *  This is a typical %queue operation.  It shrinks the %queue

       *  by one.  The time complexity of the operation depends on the

       *  underlying sequence.

       *

       *  Note that no data is returned, and if the first element's

       *  data is needed, it should be retrieved before pop() is

       *  called.

       */

      void

      pop()

      {

        __glibcxx_requires_nonempty();

        try

        {

          std::pop_heap(c.begin(), c.end(), comp);

          c.pop_back();

        }

        catch(...)

        {

          c.clear();

          __throw_exception_again;

        }

      }

    };

  // No equality/comparison operators are provided for priority_queue.

} // namespace std

#endif /* _QUEUE_H */