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

// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006
// 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>

_GLIBCXX_BEGIN_NAMESPACE(std)

  /**
   *  @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 = deque<_Tp> >
    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); }

_GLIBCXX_END_NAMESPACE

#endif /* _STACK_H */