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// std::list utilities implementation -*- C++ -*-

// Copyright (C) 2003 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.

 */

#include <list>

namespace _GLIBCXX_STD

{

  void

  _List_node_base::swap(_List_node_base& __x, _List_node_base& __y)

  {

    if ( __x._M_next != &__x )

    {

      if ( __y._M_next != &__y )

      {

        // Both __x and __y are not empty.

        std::swap(__x._M_next,__y._M_next);

        std::swap(__x._M_prev,__y._M_prev);

        __x._M_next->_M_prev = __x._M_prev->_M_next = &__x;

        __y._M_next->_M_prev = __y._M_prev->_M_next = &__y;

      }

      else

      {

        // __x is not empty, __y is empty.

        __y._M_next = __x._M_next;

        __y._M_prev = __x._M_prev;

        __y._M_next->_M_prev = __y._M_prev->_M_next = &__y;

        __x._M_next = __x._M_prev = &__x;

      }

    }

    else if ( __y._M_next != &__y )

    {

      // __x is empty, __y is not empty.

      __x._M_next = __y._M_next;

      __x._M_prev = __y._M_prev;

      __x._M_next->_M_prev = __x._M_prev->_M_next = &__x;

      __y._M_next = __y._M_prev = &__y;

    }

  }

  void

  _List_node_base::transfer(_List_node_base * const __first,

                            _List_node_base * const __last)

  {

    if (this != __last)

    {

      // Remove [first, last) from its old position.

      __last->_M_prev->_M_next  = this;

      __first->_M_prev->_M_next = __last;

      this->_M_prev->_M_next    = __first;

      // Splice [first, last) into its new position.

      _List_node_base* const __tmp = this->_M_prev;

      this->_M_prev                = __last->_M_prev;

      __last->_M_prev              = __first->_M_prev;

      __first->_M_prev             = __tmp;

    }

  }

  void

  _List_node_base::reverse()

  {

    _List_node_base* __tmp = this;

    do

    {

      std::swap(__tmp->_M_next, __tmp->_M_prev);

      __tmp = __tmp->_M_prev;     // Old next node is now prev.

    }

    while (__tmp != this);

  }

  void

  _List_node_base::hook(_List_node_base* const __position)

  {

    this->_M_next = __position;

    this->_M_prev = __position->_M_prev;

    __position->_M_prev->_M_next = this;

    __position->_M_prev = this;

  }

  void

  _List_node_base::unhook()

  {

    _List_node_base* const __next_node = this->_M_next;

    _List_node_base* const __prev_node = this->_M_prev;

    __prev_node->_M_next = __next_node;

    __next_node->_M_prev = __prev_node;

  }

} // namespace std