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// Singly-linked list implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 2004, 2005, 2007, 2008, 2009

// 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 3, 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.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

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

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// .

/*

 * Copyright (c) 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 ext/slist

 *  This file is a GNU extension to the Standard C++ Library (possibly

 *  containing extensions from the HP/SGI STL subset).

 */

#ifndef _SLIST

#define _SLIST 1

#include 

#include 

#include 

#include 

#include 

_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)

  using std::size_t;

  using std::ptrdiff_t;

  using std::_Construct;

  using std::_Destroy;

  using std::allocator;

  using std::__true_type;

  using std::__false_type;

  struct _Slist_node_base

  {

    _Slist_node_base* _M_next;

  };

  inline _Slist_node_base*

  __slist_make_link(_Slist_node_base* __prev_node,

                    _Slist_node_base* __new_node)

  {

    __new_node->_M_next = __prev_node->_M_next;

    __prev_node->_M_next = __new_node;

    return __new_node;

  }

  inline _Slist_node_base*

  __slist_previous(_Slist_node_base* __head,

                   const _Slist_node_base* __node)

  {

    while (__head && __head->_M_next != __node)

      __head = __head->_M_next;

    return __head;

  }

  inline const _Slist_node_base*

  __slist_previous(const _Slist_node_base* __head,

                   const _Slist_node_base* __node)

  {

    while (__head && __head->_M_next != __node)

      __head = __head->_M_next;

    return __head;

  }

  inline void

  __slist_splice_after(_Slist_node_base* __pos,

                       _Slist_node_base* __before_first,

                       _Slist_node_base* __before_last)

  {

    if (__pos != __before_first && __pos != __before_last)

      {

        _Slist_node_base* __first = __before_first->_M_next;

        _Slist_node_base* __after = __pos->_M_next;

        __before_first->_M_next = __before_last->_M_next;

        __pos->_M_next = __first;

        __before_last->_M_next = __after;

      }

  }

  inline void

  __slist_splice_after(_Slist_node_base* __pos, _Slist_node_base* __head)

  {

    _Slist_node_base* __before_last = __slist_previous(__head, 0);

    if (__before_last != __head)

      {

        _Slist_node_base* __after = __pos->_M_next;

        __pos->_M_next = __head->_M_next;

        __head->_M_next = 0;

        __before_last->_M_next = __after;

      }

  }

  inline _Slist_node_base*

  __slist_reverse(_Slist_node_base* __node)

  {

    _Slist_node_base* __result = __node;

    __node = __node->_M_next;

    __result->_M_next = 0;

    while(__node)

      {

        _Slist_node_base* __next = __node->_M_next;

        __node->_M_next = __result;

        __result = __node;

        __node = __next;

      }

    return __result;

  }

  inline size_t

  __slist_size(_Slist_node_base* __node)

  {

    size_t __result = 0;

    for (; __node != 0; __node = __node->_M_next)

      ++__result;

    return __result;

  }

  template 

    struct _Slist_node : public _Slist_node_base

    {

      _Tp _M_data;

    };

  struct _Slist_iterator_base

  {

    typedef size_t                    size_type;

    typedef ptrdiff_t                 difference_type;

    typedef std::forward_iterator_tag iterator_category;

    _Slist_node_base* _M_node;

    _Slist_iterator_base(_Slist_node_base* __x)

    : _M_node(__x) {}

    void

    _M_incr()

    { _M_node = _M_node->_M_next; }

    bool

    operator==(const _Slist_iterator_base& __x) const

    { return _M_node == __x._M_node; }

    bool

    operator!=(const _Slist_iterator_base& __x) const

    { return _M_node != __x._M_node; }

  };

  template 

    struct _Slist_iterator : public _Slist_iterator_base

    {

      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;

      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;

      typedef _Slist_iterator<_Tp, _Ref, _Ptr>             _Self;

      typedef _Tp              value_type;

      typedef _Ptr             pointer;

      typedef _Ref             reference;

      typedef _Slist_node<_Tp> _Node;

      explicit

      _Slist_iterator(_Node* __x)

      : _Slist_iterator_base(__x) {}

      _Slist_iterator()

      : _Slist_iterator_base(0) {}

      _Slist_iterator(const iterator& __x)

      : _Slist_iterator_base(__x._M_node) {}

      reference

      operator*() const

      { return ((_Node*) _M_node)->_M_data; }

      pointer

      operator->() const

      { return &(operator*()); }

      _Self&

      operator++()

      {

        _M_incr();

        return *this;

      }

      _Self

      operator++(int)

      {

        _Self __tmp = *this;

        _M_incr();

        return __tmp;

      }

    };

  template 

    struct _Slist_base

    : public _Alloc::template rebind<_Slist_node<_Tp> >::other

    {

      typedef typename _Alloc::template rebind<_Slist_node<_Tp> >::other

        _Node_alloc;

      typedef _Alloc allocator_type;

      allocator_type

      get_allocator() const

      { return *static_cast(this); }

      _Slist_base(const allocator_type& __a)

      : _Node_alloc(__a)

      { this->_M_head._M_next = 0; }

      ~_Slist_base()

      { _M_erase_after(&this->_M_head, 0); }

    protected:

      _Slist_node_base _M_head;

      _Slist_node<_Tp>*

      _M_get_node()

      { return _Node_alloc::allocate(1); }

      void

      _M_put_node(_Slist_node<_Tp>* __p)

      { _Node_alloc::deallocate(__p, 1); }

    protected:

      _Slist_node_base* _M_erase_after(_Slist_node_base* __pos)

      {

        _Slist_node<_Tp>* __next = (_Slist_node<_Tp>*) (__pos->_M_next);

        _Slist_node_base* __next_next = __next->_M_next;

        __pos->_M_next = __next_next;

        get_allocator().destroy(&__next->_M_data);

        _M_put_node(__next);

        return __next_next;

      }

      _Slist_node_base* _M_erase_after(_Slist_node_base*, _Slist_node_base*);

    };

  template 

    _Slist_node_base*

    _Slist_base<_Tp,_Alloc>::_M_erase_after(_Slist_node_base* __before_first,

                                            _Slist_node_base* __last_node)

    {

      _Slist_node<_Tp>* __cur = (_Slist_node<_Tp>*) (__before_first->_M_next);

      while (__cur != __last_node)

        {

          _Slist_node<_Tp>* __tmp = __cur;

          __cur = (_Slist_node<_Tp>*) __cur->_M_next;

          get_allocator().destroy(&__tmp->_M_data);

          _M_put_node(__tmp);

        }

      __before_first->_M_next = __last_node;

      return __last_node;

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

   */

  template  >

    class slist : private _Slist_base<_Tp,_Alloc>

    {

      // concept requirements

      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)

    private:

      typedef _Slist_base<_Tp,_Alloc> _Base;

    public:

      typedef _Tp               value_type;

      typedef value_type*       pointer;

      typedef const value_type* const_pointer;

      typedef value_type&       reference;

      typedef const value_type& const_reference;

      typedef size_t            size_type;

      typedef ptrdiff_t         difference_type;

      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;

      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;

      typedef typename _Base::allocator_type allocator_type;

      allocator_type

      get_allocator() const

      { return _Base::get_allocator(); }

    private:

      typedef _Slist_node<_Tp>      _Node;

      typedef _Slist_node_base      _Node_base;

      typedef _Slist_iterator_base  _Iterator_base;

      _Node*

      _M_create_node(const value_type& __x)

      {

        _Node* __node = this->_M_get_node();

        __try

          {

            get_allocator().construct(&__node->_M_data, __x);

            __node->_M_next = 0;

          }

        __catch(...)

          {

            this->_M_put_node(__node);

            __throw_exception_again;

          }

        return __node;

      }

      _Node*

      _M_create_node()

      {

        _Node* __node = this->_M_get_node();

        __try

          {

            get_allocator().construct(&__node->_M_data, value_type());

            __node->_M_next = 0;

          }

        __catch(...)

          {

            this->_M_put_node(__node);

            __throw_exception_again;

          }

        return __node;

      }

    public:

      explicit

      slist(const allocator_type& __a = allocator_type())

      : _Base(__a) {}

      slist(size_type __n, const value_type& __x,

            const allocator_type& __a =  allocator_type())

      : _Base(__a)

      { _M_insert_after_fill(&this->_M_head, __n, __x); }

      explicit

      slist(size_type __n)

      : _Base(allocator_type())

      { _M_insert_after_fill(&this->_M_head, __n, value_type()); }

      // We don't need any dispatching tricks here, because

      // _M_insert_after_range already does them.

      template 

        slist(_InputIterator __first, _InputIterator __last,

              const allocator_type& __a =  allocator_type())

        : _Base(__a)

        { _M_insert_after_range(&this->_M_head, __first, __last); }

      slist(const slist& __x)

      : _Base(__x.get_allocator())

      { _M_insert_after_range(&this->_M_head, __x.begin(), __x.end()); }

      slist&

      operator= (const slist& __x);

      ~slist() {}

    public:

      // assign(), a generalized assignment member function.  Two

      // versions: one that takes a count, and one that takes a range.

      // The range version is a member template, so we dispatch on whether

      // or not the type is an integer.

      void

      assign(size_type __n, const _Tp& __val)

      { _M_fill_assign(__n, __val); }

      void

      _M_fill_assign(size_type __n, const _Tp& __val);

      template 

        void

        assign(_InputIterator __first, _InputIterator __last)

        {

          typedef typename std::__is_integer<_InputIterator>::__type _Integral;

          _M_assign_dispatch(__first, __last, _Integral());

        }

      template 

      void

      _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)

      { _M_fill_assign((size_type) __n, (_Tp) __val); }

      template 

      void

      _M_assign_dispatch(_InputIterator __first, _InputIterator __last,

                         __false_type);

    public:

      iterator

      begin()

      { return iterator((_Node*)this->_M_head._M_next); }

      const_iterator

      begin() const

      { return const_iterator((_Node*)this->_M_head._M_next);}

      iterator

      end()

      { return iterator(0); }

      const_iterator

      end() const

      { return const_iterator(0); }

      // Experimental new feature: before_begin() returns a

      // non-dereferenceable iterator that, when incremented, yields

      // begin().  This iterator may be used as the argument to

      // insert_after, erase_after, etc.  Note that even for an empty

      // slist, before_begin() is not the same iterator as end().  It

      // is always necessary to increment before_begin() at least once to

      // obtain end().

      iterator

      before_begin()

      { return iterator((_Node*) &this->_M_head); }

      const_iterator

      before_begin() const

      { return const_iterator((_Node*) &this->_M_head); }

      size_type

      size() const

      { return __slist_size(this->_M_head._M_next); }

      size_type

      max_size() const

      { return size_type(-1); }

      bool

      empty() const

      { return this->_M_head._M_next == 0; }

      void

      swap(slist& __x)

      { std::swap(this->_M_head._M_next, __x._M_head._M_next); }

    public:

      reference

      front()

      { return ((_Node*) this->_M_head._M_next)->_M_data; }

      const_reference

      front() const

      { return ((_Node*) this->_M_head._M_next)->_M_data; }

      void

      push_front(const value_type& __x)

      { __slist_make_link(&this->_M_head, _M_create_node(__x)); }

      void

      push_front()

      { __slist_make_link(&this->_M_head, _M_create_node()); }

      void

      pop_front()

      {

        _Node* __node = (_Node*) this->_M_head._M_next;

        this->_M_head._M_next = __node->_M_next;

        get_allocator().destroy(&__node->_M_data);

        this->_M_put_node(__node);

      }

      iterator

      previous(const_iterator __pos)

      { return iterator((_Node*) __slist_previous(&this->_M_head,

                                                  __pos._M_node)); }

      const_iterator

      previous(const_iterator __pos) const

      { return const_iterator((_Node*) __slist_previous(&this->_M_head,

                                                        __pos._M_node)); }

    private:

      _Node*

      _M_insert_after(_Node_base* __pos, const value_type& __x)

      { return (_Node*) (__slist_make_link(__pos, _M_create_node(__x))); }

      _Node*

      _M_insert_after(_Node_base* __pos)

      { return (_Node*) (__slist_make_link(__pos, _M_create_node())); }

      void

      _M_insert_after_fill(_Node_base* __pos,

                           size_type __n, const value_type& __x)

      {

        for (size_type __i = 0; __i < __n; ++__i)

          __pos = __slist_make_link(__pos, _M_create_node(__x));

      }

      // Check whether it's an integral type.  If so, it's not an iterator.

      template 

        void

        _M_insert_after_range(_Node_base* __pos,

                              _InIterator __first, _InIterator __last)

        {

          typedef typename std::__is_integer<_InIterator>::__type _Integral;

          _M_insert_after_range(__pos, __first, __last, _Integral());

        }

      template 

        void

        _M_insert_after_range(_Node_base* __pos, _Integer __n, _Integer __x,

                              __true_type)

        { _M_insert_after_fill(__pos, __n, __x); }

      template 

        void

        _M_insert_after_range(_Node_base* __pos,

                              _InIterator __first, _InIterator __last,

                              __false_type)

        {

          while (__first != __last)

            {

              __pos = __slist_make_link(__pos, _M_create_node(*__first));

              ++__first;

            }

        }

    public:

      iterator

      insert_after(iterator __pos, const value_type& __x)

      { return iterator(_M_insert_after(__pos._M_node, __x)); }

      iterator

      insert_after(iterator __pos)

      { return insert_after(__pos, value_type()); }

      void

      insert_after(iterator __pos, size_type __n, const value_type& __x)

      { _M_insert_after_fill(__pos._M_node, __n, __x); }

      // We don't need any dispatching tricks here, because

      // _M_insert_after_range already does them.

      template 

        void

        insert_after(iterator __pos, _InIterator __first, _InIterator __last)

        { _M_insert_after_range(__pos._M_node, __first, __last); }

      iterator

      insert(iterator __pos, const value_type& __x)

      { return iterator(_M_insert_after(__slist_previous(&this->_M_head,

                                                         __pos._M_node),

                                        __x)); }

      iterator

      insert(iterator __pos)

      { return iterator(_M_insert_after(__slist_previous(&this->_M_head,

                                                         __pos._M_node),

                                        value_type())); }

      void

      insert(iterator __pos, size_type __n, const value_type& __x)

      { _M_insert_after_fill(__slist_previous(&this->_M_head, __pos._M_node),

                             __n, __x); }

      // We don't need any dispatching tricks here, because

      // _M_insert_after_range already does them.

      template 

        void

        insert(iterator __pos, _InIterator __first, _InIterator __last)

        { _M_insert_after_range(__slist_previous(&this->_M_head, __pos._M_node),

                                __first, __last); }

    public:

      iterator

      erase_after(iterator __pos)

      { return iterator((_Node*) this->_M_erase_after(__pos._M_node)); }

      iterator

      erase_after(iterator __before_first, iterator __last)

      {

        return iterator((_Node*) this->_M_erase_after(__before_first._M_node,

                                                      __last._M_node));

      }

      iterator

      erase(iterator __pos)

      {

        return iterator((_Node*) this->_M_erase_after

                        (__slist_previous(&this->_M_head, __pos._M_node)));

      }

      iterator

      erase(iterator __first, iterator __last)

      {

        return iterator((_Node*) this->_M_erase_after

                        (__slist_previous(&this->_M_head, __first._M_node),

                         __last._M_node));

      }

      void

      resize(size_type new_size, const _Tp& __x);

      void

      resize(size_type new_size)

      { resize(new_size, _Tp()); }

      void

      clear()

      { this->_M_erase_after(&this->_M_head, 0); }

    public:

      // Moves the range [__before_first + 1, __before_last + 1) to *this,

      //  inserting it immediately after __pos.  This is constant time.

      void

      splice_after(iterator __pos,

                   iterator __before_first, iterator __before_last)

      {

        if (__before_first != __before_last)

          __slist_splice_after(__pos._M_node, __before_first._M_node,

                               __before_last._M_node);

      }

      // Moves the element that follows __prev to *this, inserting it

      // immediately after __pos.  This is constant time.

      void

      splice_after(iterator __pos, iterator __prev)

      { __slist_splice_after(__pos._M_node,

                             __prev._M_node, __prev._M_node->_M_next); }

      // Removes all of the elements from the list __x to *this, inserting

      // them immediately after __pos.  __x must not be *this.  Complexity:

      // linear in __x.size().

      void

      splice_after(iterator __pos, slist& __x)

      { __slist_splice_after(__pos._M_node, &__x._M_head); }

      // Linear in distance(begin(), __pos), and linear in __x.size().

      void

      splice(iterator __pos, slist& __x)

      {

        if (__x._M_head._M_next)

          __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),

                               &__x._M_head,

                               __slist_previous(&__x._M_head, 0)); }

      // Linear in distance(begin(), __pos), and in distance(__x.begin(), __i).

      void

      splice(iterator __pos, slist& __x, iterator __i)

      { __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),

                             __slist_previous(&__x._M_head, __i._M_node),

                             __i._M_node); }

      // Linear in distance(begin(), __pos), in distance(__x.begin(), __first),

      // and in distance(__first, __last).

      void

      splice(iterator __pos, slist& __x, iterator __first, iterator __last)

      {

        if (__first != __last)

          __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),

                               __slist_previous(&__x._M_head, __first._M_node),

                               __slist_previous(__first._M_node,

                                                __last._M_node));

      }

    public:

      void

      reverse()

      {

        if (this->_M_head._M_next)

          this->_M_head._M_next = __slist_reverse(this->_M_head._M_next);

      }

      void

      remove(const _Tp& __val);

      void

      unique();

      void

      merge(slist& __x);

      void

      sort();

      template 

        void

        remove_if(_Predicate __pred);

      template 

        void

        unique(_BinaryPredicate __pred);

      template 

        void

        merge(slist&, _StrictWeakOrdering);

      template 

        void

        sort(_StrictWeakOrdering __comp);

    };

  template 

    slist<_Tp, _Alloc>&

    slist<_Tp, _Alloc>::operator=(const slist<_Tp, _Alloc>& __x)

    {

      if (&__x != this)

        {

          _Node_base* __p1 = &this->_M_head;

          _Node* __n1 = (_Node*) this->_M_head._M_next;

          const _Node* __n2 = (const _Node*) __x._M_head._M_next;

          while (__n1 && __n2)

            {

              __n1->_M_data = __n2->_M_data;

              __p1 = __n1;

              __n1 = (_Node*) __n1->_M_next;

              __n2 = (const _Node*) __n2->_M_next;

            }

          if (__n2 == 0)

            this->_M_erase_after(__p1, 0);

          else

            _M_insert_after_range(__p1, const_iterator((_Node*)__n2),

                                  const_iterator(0));

        }

      return *this;

    }

  template 

    void

    slist<_Tp, _Alloc>::_M_fill_assign(size_type __n, const _Tp& __val)

    {

      _Node_base* __prev = &this->_M_head;

      _Node* __node = (_Node*) this->_M_head._M_next;

      for (; __node != 0 && __n > 0; --__n)

        {

          __node->_M_data = __val;

          __prev = __node;

          __node = (_Node*) __node->_M_next;

        }

      if (__n > 0)

        _M_insert_after_fill(__prev, __n, __val);

      else

        this->_M_erase_after(__prev, 0);

    }

  template 

    template 

      void

      slist<_Tp, _Alloc>::_M_assign_dispatch(_InputIterator __first,

                                             _InputIterator __last,

                                             __false_type)

      {

        _Node_base* __prev = &this->_M_head;

        _Node* __node = (_Node*) this->_M_head._M_next;

        while (__node != 0 && __first != __last)

          {

            __node->_M_data = *__first;

            __prev = __node;

            __node = (_Node*) __node->_M_next;

            ++__first;

          }

        if (__first != __last)

          _M_insert_after_range(__prev, __first, __last);

        else

          this->_M_erase_after(__prev, 0);

      }

  template 

    inline bool

    operator==(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    {

      typedef typename slist<_Tp,_Alloc>::const_iterator const_iterator;

      const_iterator __end1 = _SL1.end();

      const_iterator __end2 = _SL2.end();

      const_iterator __i1 = _SL1.begin();

      const_iterator __i2 = _SL2.begin();

      while (__i1 != __end1 && __i2 != __end2 && *__i1 == *__i2)

        {

          ++__i1;

          ++__i2;

        }

      return __i1 == __end1 && __i2 == __end2;

    }

  template 

    inline bool

    operator<(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    { return std::lexicographical_compare(_SL1.begin(), _SL1.end(),

                                          _SL2.begin(), _SL2.end()); }

  template 

    inline bool

    operator!=(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    { return !(_SL1 == _SL2); }

  template 

    inline bool

    operator>(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    { return _SL2 < _SL1; }

  template 

    inline bool

    operator<=(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    { return !(_SL2 < _SL1); }

  template 

    inline bool

    operator>=(const slist<_Tp, _Alloc>& _SL1, const slist<_Tp, _Alloc>& _SL2)

    { return !(_SL1 < _SL2); }

  template 

    inline void

    swap(slist<_Tp, _Alloc>& __x, slist<_Tp, _Alloc>& __y)

    { __x.swap(__y); }

  template 

    void

    slist<_Tp, _Alloc>::resize(size_type __len, const _Tp& __x)

    {

      _Node_base* __cur = &this->_M_head;

      while (__cur->_M_next != 0 && __len > 0)

        {

          --__len;

          __cur = __cur->_M_next;

        }

      if (__cur->_M_next)

        this->_M_erase_after(__cur, 0);

      else

        _M_insert_after_fill(__cur, __len, __x);

    }

  template 

    void

    slist<_Tp, _Alloc>::remove(const _Tp& __val)

    {

      _Node_base* __cur = &this->_M_head;

      while (__cur && __cur->_M_next)

        {

          if (((_Node*) __cur->_M_next)->_M_data == __val)

            this->_M_erase_after(__cur);

          else

            __cur = __cur->_M_next;

        }

    }

  template 

    void

    slist<_Tp, _Alloc>::unique()

    {

      _Node_base* __cur = this->_M_head._M_next;

      if (__cur)

        {

          while (__cur->_M_next)

            {

              if (((_Node*)__cur)->_M_data

                  == ((_Node*)(__cur->_M_next))->_M_data)

                this->_M_erase_after(__cur);

              else

                __cur = __cur->_M_next;

            }

        }

    }

  template 

    void

    slist<_Tp, _Alloc>::merge(slist<_Tp, _Alloc>& __x)

    {

      _Node_base* __n1 = &this->_M_head;

      while (__n1->_M_next && __x._M_head._M_next)

        {

          if (((_Node*) __x._M_head._M_next)->_M_data

              < ((_Node*) __n1->_M_next)->_M_data)

            __slist_splice_after(__n1, &__x._M_head, __x._M_head._M_next);

          __n1 = __n1->_M_next;

        }

      if (__x._M_head._M_next)

        {

          __n1->_M_next = __x._M_head._M_next;

          __x._M_head._M_next = 0;

        }

    }

  template 

    void

    slist<_Tp, _Alloc>::sort()

    {

      if (this->_M_head._M_next && this->_M_head._M_next->_M_next)

        {

          slist __carry;

          slist __counter[64];

          int __fill = 0;

          while (!empty())

            {

              __slist_splice_after(&__carry._M_head,

                                   &this->_M_head, this->_M_head._M_next);

              int __i = 0;

              while (__i < __fill && !__counter[__i].empty())

                {

                  __counter[__i].merge(__carry);

                  __carry.swap(__counter[__i]);

                  ++__i;

                }

              __carry.swap(__counter[__i]);

              if (__i == __fill)

                ++__fill;

            }

          for (int __i = 1; __i < __fill; ++__i)

            __counter[__i].merge(__counter[__i-1]);

          this->swap(__counter[__fill-1]);