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// Stack implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 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_stack.h

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

 *  You should not attempt to use it directly.

 */

#ifndef _STACK_H

#define _STACK_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 stack;

  template<typename _Tp, typename _Seq>

    inline bool

    operator==(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y);

  template<typename _Tp, typename _Seq>

    inline bool

    operator<(const stack<_Tp,_Seq>& __x, const stack<_Tp,_Seq>& __y);

  /**

   *  @brief  A standard container giving FILO 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-last-out %stack 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 back, @c push_back, and @c pop_front,

   *  such as std::list, std::vector, 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, @c pop, and @c top, which are standard %stack/FILO

   *  operations.

  */

  template<typename _Tp, typename _Sequence>

    class stack

    {

      // concept requirements

      typedef typename _Sequence::value_type _Sequence_value_type;

      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)

      __glibcxx_class_requires(_Sequence, _BackInsertionSequenceConcept)

      __glibcxx_class_requires2(_Tp, _Sequence_value_type, _SameTypeConcept)

      template<typename _Tp1, typename _Seq1>

        friend bool

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

      template<typename _Tp1, typename _Seq1>

        friend bool

        operator<(const stack<_Tp1, _Seq1>&, const stack<_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:

      //  See queue::c for notes on this name.

      _Sequence c;

    public:

      // XXX removed old def ctor, added def arg to this one to match 14882

      /**

       *  @brief  Default constructor creates no elements.

       */

      explicit

      stack(const _Sequence& __c = _Sequence())

      : c(__c) {}

      /**

       *  Returns true if the %stack is empty.

       */

      bool

      empty() const

      { return c.empty(); }

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

      size_type

      size() const

      { return c.size(); }

      /**

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

       *  element of the %stack.

       */

      reference

      top()

      {

        __glibcxx_requires_nonempty();

        return c.back();

      }

      /**

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

       *  element of the %stack.

       */

      const_reference

      top() const

      {

        __glibcxx_requires_nonempty();

        return c.back();

      }

      /**

       *  @brief  Add data to the top of the %stack.

       *  @param  x  Data to be added.

       *

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

       *  element at the top of the %stack 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 %stack operation.  It shrinks the %stack

       *  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_back();

      }

    };

  /**

   *  @brief  Stack equality comparison.

   *  @param  x  A %stack.

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

   *  @return  True iff the size and elements of the stacks 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

   *  stacks are considered equivalent if their sequences compare

   *  equal.

  */

  template<typename _Tp, typename _Seq>

    inline bool

    operator==(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

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

  /**

   *  @brief  Stack ordering relation.

   *  @param  x  A %stack.

   *  @param  y  A %stack 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 _Seq>

    inline bool

    operator<(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

    { return __x.c < __y.c; }

  /// Based on operator==

  template<typename _Tp, typename _Seq>

    inline bool

    operator!=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

    { return !(__x == __y); }

  /// Based on operator<

  template<typename _Tp, typename _Seq>

    inline bool

    operator>(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

    { return __y < __x; }

  /// Based on operator<

  template<typename _Tp, typename _Seq>

    inline bool

    operator<=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

    { return !(__y < __x); }

  /// Based on operator<

  template<typename _Tp, typename _Seq>

    inline bool

    operator>=(const stack<_Tp, _Seq>& __x, const stack<_Tp, _Seq>& __y)

    { return !(__x < __y); }

} // namespace std

#endif /* _STACK_H */