// List implementation -*- C++ -*-
	
	// Copyright (C) 2001-2013 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
	// <http://www.gnu.org/licenses/>.
	
	/*
	 *
	 * 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 bits/stl_list.h
	 *  This is an internal header file, included by other library headers.
	 *  Do not attempt to use it directly. @headername{list}
	 */
	
	#ifndef _STL_LIST_H
	#define _STL_LIST_H 1
	
	#include <bits/concept_check.h>
	#if __cplusplus >= 201103L
	#include <initializer_list>
	#endif
	
	namespace std _GLIBCXX_VISIBILITY(default)
	{
	  namespace __detail
	  {
	  _GLIBCXX_BEGIN_NAMESPACE_VERSION
	
	    // Supporting structures are split into common and templated
	    // types; the latter publicly inherits from the former in an
	    // effort to reduce code duplication.  This results in some
	    // "needless" static_cast'ing later on, but it's all safe
	    // downcasting.
	
	    /// Common part of a node in the %list. 
	    struct _List_node_base
	    {
	      _List_node_base* _M_next;
	      _List_node_base* _M_prev;
	
	      static void
	      swap(_List_node_base& __x, _List_node_base& __y) _GLIBCXX_USE_NOEXCEPT;
	
	      void
	      _M_transfer(_List_node_base* const __first,
			  _List_node_base* const __last) _GLIBCXX_USE_NOEXCEPT;
	
	      void
	      _M_reverse() _GLIBCXX_USE_NOEXCEPT;
	
	      void
	      _M_hook(_List_node_base* const __position) _GLIBCXX_USE_NOEXCEPT;
	
	      void
	      _M_unhook() _GLIBCXX_USE_NOEXCEPT;
	    };
	
	  _GLIBCXX_END_NAMESPACE_VERSION
	  } // namespace detail
	
	_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
	
	  /// An actual node in the %list.
	  template<typename _Tp>
	    struct _List_node : public __detail::_List_node_base
	    {
	      ///< User's data.
	      _Tp _M_data;
	
	#if __cplusplus >= 201103L
	      template<typename... _Args>
	        _List_node(_Args&&... __args)
		: __detail::_List_node_base(), _M_data(std::forward<_Args>(__args)...) 
	        { }
	#endif
	    };
	
	  /**
	   *  @brief A list::iterator.
	   *
	   *  All the functions are op overloads.
	  */
	  template<typename _Tp>
	    struct _List_iterator
	    {
	      typedef _List_iterator<_Tp>                _Self;
	      typedef _List_node<_Tp>                    _Node;
	
	      typedef ptrdiff_t                          difference_type;
	      typedef std::bidirectional_iterator_tag    iterator_category;
	      typedef _Tp                                value_type;
	      typedef _Tp*                               pointer;
	      typedef _Tp&                               reference;
	
	      _List_iterator()
	      : _M_node() { }
	
	      explicit
	      _List_iterator(__detail::_List_node_base* __x)
	      : _M_node(__x) { }
	
	      // Must downcast from _List_node_base to _List_node to get to _M_data.
	      reference
	      operator*() const
	      { return static_cast<_Node*>(_M_node)->_M_data; }
	
	      pointer
	      operator->() const
	      { return std::__addressof(static_cast<_Node*>(_M_node)->_M_data); }
	
	      _Self&
	      operator++()
	      {
		_M_node = _M_node->_M_next;
		return *this;
	      }
	
	      _Self
	      operator++(int)
	      {
		_Self __tmp = *this;
		_M_node = _M_node->_M_next;
		return __tmp;
	      }
	
	      _Self&
	      operator--()
	      {
		_M_node = _M_node->_M_prev;
		return *this;
	      }
	
	      _Self
	      operator--(int)
	      {
		_Self __tmp = *this;
		_M_node = _M_node->_M_prev;
		return __tmp;
	      }
	
	      bool
	      operator==(const _Self& __x) const
	      { return _M_node == __x._M_node; }
	
	      bool
	      operator!=(const _Self& __x) const
	      { return _M_node != __x._M_node; }
	
	      // The only member points to the %list element.
	      __detail::_List_node_base* _M_node;
	    };
	
	  /**
	   *  @brief A list::const_iterator.
	   *
	   *  All the functions are op overloads.
	  */
	  template<typename _Tp>
	    struct _List_const_iterator
	    {
	      typedef _List_const_iterator<_Tp>          _Self;
	      typedef const _List_node<_Tp>              _Node;
	      typedef _List_iterator<_Tp>                iterator;
	
	      typedef ptrdiff_t                          difference_type;
	      typedef std::bidirectional_iterator_tag    iterator_category;
	      typedef _Tp                                value_type;
	      typedef const _Tp*                         pointer;
	      typedef const _Tp&                         reference;
	
	      _List_const_iterator()
	      : _M_node() { }
	
	      explicit
	      _List_const_iterator(const __detail::_List_node_base* __x)
	      : _M_node(__x) { }
	
	      _List_const_iterator(const iterator& __x)
	      : _M_node(__x._M_node) { }
	
	      // Must downcast from List_node_base to _List_node to get to
	      // _M_data.
	      reference
	      operator*() const
	      { return static_cast<_Node*>(_M_node)->_M_data; }
	
	      pointer
	      operator->() const
	      { return std::__addressof(static_cast<_Node*>(_M_node)->_M_data); }
	
	      _Self&
	      operator++()
	      {
		_M_node = _M_node->_M_next;
		return *this;
	      }
	
	      _Self
	      operator++(int)
	      {
		_Self __tmp = *this;
		_M_node = _M_node->_M_next;
		return __tmp;
	      }
	
	      _Self&
	      operator--()
	      {
		_M_node = _M_node->_M_prev;
		return *this;
	      }
	
	      _Self
	      operator--(int)
	      {
		_Self __tmp = *this;
		_M_node = _M_node->_M_prev;
		return __tmp;
	      }
	
	      bool
	      operator==(const _Self& __x) const
	      { return _M_node == __x._M_node; }
	
	      bool
	      operator!=(const _Self& __x) const
	      { return _M_node != __x._M_node; }
	
	      // The only member points to the %list element.
	      const __detail::_List_node_base* _M_node;
	    };
	
	  template<typename _Val>
	    inline bool
	    operator==(const _List_iterator<_Val>& __x,
		       const _List_const_iterator<_Val>& __y)
	    { return __x._M_node == __y._M_node; }
	
	  template<typename _Val>
	    inline bool
	    operator!=(const _List_iterator<_Val>& __x,
	               const _List_const_iterator<_Val>& __y)
	    { return __x._M_node != __y._M_node; }
	
	
	  /// See bits/stl_deque.h's _Deque_base for an explanation.
	  template<typename _Tp, typename _Alloc>
	    class _List_base
	    {
	    protected:
	      // NOTA BENE
	      // The stored instance is not actually of "allocator_type"'s
	      // type.  Instead we rebind the type to
	      // Allocator<List_node<Tp>>, which according to [20.1.5]/4
	      // should probably be the same.  List_node<Tp> is not the same
	      // size as Tp (it's two pointers larger), and specializations on
	      // Tp may go unused because List_node<Tp> is being bound
	      // instead.
	      //
	      // We put this to the test in the constructors and in
	      // get_allocator, where we use conversions between
	      // allocator_type and _Node_alloc_type. The conversion is
	      // required by table 32 in [20.1.5].
	      typedef typename _Alloc::template rebind<_List_node<_Tp> >::other
	        _Node_alloc_type;
	
	      typedef typename _Alloc::template rebind<_Tp>::other _Tp_alloc_type;
	
	      struct _List_impl
	      : public _Node_alloc_type
	      {
		__detail::_List_node_base _M_node;
	
		_List_impl()
		: _Node_alloc_type(), _M_node()
		{ }
	
		_List_impl(const _Node_alloc_type& __a)
		: _Node_alloc_type(__a), _M_node()
		{ }
	
	#if __cplusplus >= 201103L
		_List_impl(_Node_alloc_type&& __a)
		: _Node_alloc_type(std::move(__a)), _M_node()
		{ }
	#endif
	      };
	
	      _List_impl _M_impl;
	
	      _List_node<_Tp>*
	      _M_get_node()
	      { return _M_impl._Node_alloc_type::allocate(1); }
	
	      void
	      _M_put_node(_List_node<_Tp>* __p)
	      { _M_impl._Node_alloc_type::deallocate(__p, 1); }
	
	  public:
	      typedef _Alloc allocator_type;
	
	      _Node_alloc_type&
	      _M_get_Node_allocator() _GLIBCXX_NOEXCEPT
	      { return *static_cast<_Node_alloc_type*>(&_M_impl); }
	
	      const _Node_alloc_type&
	      _M_get_Node_allocator() const _GLIBCXX_NOEXCEPT
	      { return *static_cast<const _Node_alloc_type*>(&_M_impl); }
	
	      _Tp_alloc_type
	      _M_get_Tp_allocator() const _GLIBCXX_NOEXCEPT
	      { return _Tp_alloc_type(_M_get_Node_allocator()); }
	
	      allocator_type
	      get_allocator() const _GLIBCXX_NOEXCEPT
	      { return allocator_type(_M_get_Node_allocator()); }
	
	      _List_base()
	      : _M_impl()
	      { _M_init(); }
	
	      _List_base(const _Node_alloc_type& __a)
	      : _M_impl(__a)
	      { _M_init(); }
	
	#if __cplusplus >= 201103L
	      _List_base(_List_base&& __x)
	      : _M_impl(std::move(__x._M_get_Node_allocator()))
	      {
		_M_init();
		__detail::_List_node_base::swap(_M_impl._M_node, __x._M_impl._M_node);
	      }
	#endif
	
	      // This is what actually destroys the list.
	      ~_List_base() _GLIBCXX_NOEXCEPT
	      { _M_clear(); }
	
	      void
	      _M_clear();
	
	      void
	      _M_init()
	      {
	        this->_M_impl._M_node._M_next = &this->_M_impl._M_node;
	        this->_M_impl._M_node._M_prev = &this->_M_impl._M_node;
	      }
	    };
	
	  /**
	   *  @brief A standard container with linear time access to elements,
	   *  and fixed time insertion/deletion at any point in the sequence.
	   *
	   *  @ingroup sequences
	   *
	   *  @tparam _Tp  Type of element.
	   *  @tparam _Alloc  Allocator type, defaults to allocator<_Tp>.
	   *
	   *  Meets the requirements of a <a href="tables.html#65">container</a>, a
	   *  <a href="tables.html#66">reversible container</a>, and a
	   *  <a href="tables.html#67">sequence</a>, including the
	   *  <a href="tables.html#68">optional sequence requirements</a> with the
	   *  %exception of @c at and @c operator[].
	   *
	   *  This is a @e doubly @e linked %list.  Traversal up and down the
	   *  %list requires linear time, but adding and removing elements (or
	   *  @e nodes) is done in constant time, regardless of where the
	   *  change takes place.  Unlike std::vector and std::deque,
	   *  random-access iterators are not provided, so subscripting ( @c
	   *  [] ) access is not allowed.  For algorithms which only need
	   *  sequential access, this lack makes no difference.
	   *
	   *  Also unlike the other standard containers, std::list provides
	   *  specialized algorithms %unique to linked lists, such as
	   *  splicing, sorting, and in-place reversal.
	   *
	   *  A couple points on memory allocation for list<Tp>:
	   *
	   *  First, we never actually allocate a Tp, we allocate
	   *  List_node<Tp>'s and trust [20.1.5]/4 to DTRT.  This is to ensure
	   *  that after elements from %list<X,Alloc1> are spliced into
	   *  %list<X,Alloc2>, destroying the memory of the second %list is a
	   *  valid operation, i.e., Alloc1 giveth and Alloc2 taketh away.
	   *
	   *  Second, a %list conceptually represented as
	   *  @code
	   *    A <---> B <---> C <---> D
	   *  @endcode
	   *  is actually circular; a link exists between A and D.  The %list
	   *  class holds (as its only data member) a private list::iterator
	   *  pointing to @e D, not to @e A!  To get to the head of the %list,
	   *  we start at the tail and move forward by one.  When this member
	   *  iterator's next/previous pointers refer to itself, the %list is
	   *  %empty. 
	  */
	  template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
	    class list : protected _List_base<_Tp, _Alloc>
	    {
	      // concept requirements
	      typedef typename _Alloc::value_type                _Alloc_value_type;
	      __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
	      __glibcxx_class_requires2(_Tp, _Alloc_value_type, _SameTypeConcept)
	
	      typedef _List_base<_Tp, _Alloc>                    _Base;
	      typedef typename _Base::_Tp_alloc_type		 _Tp_alloc_type;
	      typedef typename _Base::_Node_alloc_type		 _Node_alloc_type;
	
	    public:
	      typedef _Tp                                        value_type;
	      typedef typename _Tp_alloc_type::pointer           pointer;
	      typedef typename _Tp_alloc_type::const_pointer     const_pointer;
	      typedef typename _Tp_alloc_type::reference         reference;
	      typedef typename _Tp_alloc_type::const_reference   const_reference;
	      typedef _List_iterator<_Tp>                        iterator;
	      typedef _List_const_iterator<_Tp>                  const_iterator;
	      typedef std::reverse_iterator<const_iterator>      const_reverse_iterator;
	      typedef std::reverse_iterator<iterator>            reverse_iterator;
	      typedef size_t                                     size_type;
	      typedef ptrdiff_t                                  difference_type;
	      typedef _Alloc                                     allocator_type;
	
	    protected:
	      // Note that pointers-to-_Node's can be ctor-converted to
	      // iterator types.
	      typedef _List_node<_Tp>				 _Node;
	
	      using _Base::_M_impl;
	      using _Base::_M_put_node;
	      using _Base::_M_get_node;
	      using _Base::_M_get_Tp_allocator;
	      using _Base::_M_get_Node_allocator;
	
	      /**
	       *  @param  __args  An instance of user data.
	       *
	       *  Allocates space for a new node and constructs a copy of
	       *  @a __args in it.
	       */
	#if __cplusplus < 201103L
	      _Node*
	      _M_create_node(const value_type& __x)
	      {
		_Node* __p = this->_M_get_node();
		__try
		  {
		    _M_get_Tp_allocator().construct
		      (std::__addressof(__p->_M_data), __x);
		  }
		__catch(...)
		  {
		    _M_put_node(__p);
		    __throw_exception_again;
		  }
		return __p;
	      }
	#else
	      template<typename... _Args>
	        _Node*
	        _M_create_node(_Args&&... __args)
		{
		  _Node* __p = this->_M_get_node();
		  __try
		    {
		      _M_get_Node_allocator().construct(__p,
							std::forward<_Args>(__args)...);
		    }
		  __catch(...)
		    {
		      _M_put_node(__p);
		      __throw_exception_again;
		    }
		  return __p;
		}
	#endif
	
	    public:
	      // [23.2.2.1] construct/copy/destroy
	      // (assign() and get_allocator() are also listed in this section)
	      /**
	       *  @brief  Default constructor creates no elements.
	       */
	      list()
	      : _Base() { }
	
	      /**
	       *  @brief  Creates a %list with no elements.
	       *  @param  __a  An allocator object.
	       */
	      explicit
	      list(const allocator_type& __a)
	      : _Base(_Node_alloc_type(__a)) { }
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  Creates a %list with default constructed elements.
	       *  @param  __n  The number of elements to initially create.
	       *
	       *  This constructor fills the %list with @a __n default
	       *  constructed elements.
	       */
	      explicit
	      list(size_type __n)
	      : _Base()
	      { _M_default_initialize(__n); }
	
	      /**
	       *  @brief  Creates a %list with copies of an exemplar element.
	       *  @param  __n  The number of elements to initially create.
	       *  @param  __value  An element to copy.
	       *  @param  __a  An allocator object.
	       *
	       *  This constructor fills the %list with @a __n copies of @a __value.
	       */
	      list(size_type __n, const value_type& __value,
		   const allocator_type& __a = allocator_type())
	      : _Base(_Node_alloc_type(__a))
	      { _M_fill_initialize(__n, __value); }
	#else
	      /**
	       *  @brief  Creates a %list with copies of an exemplar element.
	       *  @param  __n  The number of elements to initially create.
	       *  @param  __value  An element to copy.
	       *  @param  __a  An allocator object.
	       *
	       *  This constructor fills the %list with @a __n copies of @a __value.
	       */
	      explicit
	      list(size_type __n, const value_type& __value = value_type(),
		   const allocator_type& __a = allocator_type())
	      : _Base(_Node_alloc_type(__a))
	      { _M_fill_initialize(__n, __value); }
	#endif
	
	      /**
	       *  @brief  %List copy constructor.
	       *  @param  __x  A %list of identical element and allocator types.
	       *
	       *  The newly-created %list uses a copy of the allocation object used
	       *  by @a __x.
	       */
	      list(const list& __x)
	      : _Base(__x._M_get_Node_allocator())
	      { _M_initialize_dispatch(__x.begin(), __x.end(), __false_type()); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  %List move constructor.
	       *  @param  __x  A %list of identical element and allocator types.
	       *
	       *  The newly-created %list contains the exact contents of @a __x.
	       *  The contents of @a __x are a valid, but unspecified %list.
	       */
	      list(list&& __x) noexcept
	      : _Base(std::move(__x)) { }
	
	      /**
	       *  @brief  Builds a %list from an initializer_list
	       *  @param  __l  An initializer_list of value_type.
	       *  @param  __a  An allocator object.
	       *
	       *  Create a %list consisting of copies of the elements in the
	       *  initializer_list @a __l.  This is linear in __l.size().
	       */
	      list(initializer_list<value_type> __l,
	           const allocator_type& __a = allocator_type())
	      : _Base(_Node_alloc_type(__a))
	      { _M_initialize_dispatch(__l.begin(), __l.end(), __false_type()); }
	#endif
	
	      /**
	       *  @brief  Builds a %list from a range.
	       *  @param  __first  An input iterator.
	       *  @param  __last  An input iterator.
	       *  @param  __a  An allocator object.
	       *
	       *  Create a %list consisting of copies of the elements from
	       *  [@a __first,@a __last).  This is linear in N (where N is
	       *  distance(@a __first,@a __last)).
	       */
	#if __cplusplus >= 201103L
	      template<typename _InputIterator,
		       typename = std::_RequireInputIter<_InputIterator>>
	        list(_InputIterator __first, _InputIterator __last,
		     const allocator_type& __a = allocator_type())
		: _Base(_Node_alloc_type(__a))
	        { _M_initialize_dispatch(__first, __last, __false_type()); }
	#else
	      template<typename _InputIterator>
	        list(_InputIterator __first, _InputIterator __last,
		     const allocator_type& __a = allocator_type())
		: _Base(_Node_alloc_type(__a))
	        { 
		  // Check whether it's an integral type.  If so, it's not an iterator.
		  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
		  _M_initialize_dispatch(__first, __last, _Integral());
		}
	#endif
	
	      /**
	       *  No explicit dtor needed as the _Base dtor takes care of
	       *  things.  The _Base dtor only erases the elements, and note
	       *  that if the elements themselves are pointers, the pointed-to
	       *  memory is not touched in any way.  Managing the pointer is
	       *  the user's responsibility.
	       */
	
	      /**
	       *  @brief  %List assignment operator.
	       *  @param  __x  A %list of identical element and allocator types.
	       *
	       *  All the elements of @a __x are copied, but unlike the copy
	       *  constructor, the allocator object is not copied.
	       */
	      list&
	      operator=(const list& __x);
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  %List move assignment operator.
	       *  @param  __x  A %list of identical element and allocator types.
	       *
	       *  The contents of @a __x are moved into this %list (without copying).
	       *  @a __x is a valid, but unspecified %list
	       */
	      list&
	      operator=(list&& __x)
	      {
		// NB: DR 1204.
		// NB: DR 675.
		this->clear();
		this->swap(__x);
		return *this;
	      }
	
	      /**
	       *  @brief  %List initializer list assignment operator.
	       *  @param  __l  An initializer_list of value_type.
	       *
	       *  Replace the contents of the %list with copies of the elements
	       *  in the initializer_list @a __l.  This is linear in l.size().
	       */
	      list&
	      operator=(initializer_list<value_type> __l)
	      {
		this->assign(__l.begin(), __l.end());
		return *this;
	      }
	#endif
	
	      /**
	       *  @brief  Assigns a given value to a %list.
	       *  @param  __n  Number of elements to be assigned.
	       *  @param  __val  Value to be assigned.
	       *
	       *  This function fills a %list with @a __n copies of the given
	       *  value.  Note that the assignment completely changes the %list
	       *  and that the resulting %list's size is the same as the number
	       *  of elements assigned.  Old data may be lost.
	       */
	      void
	      assign(size_type __n, const value_type& __val)
	      { _M_fill_assign(__n, __val); }
	
	      /**
	       *  @brief  Assigns a range to a %list.
	       *  @param  __first  An input iterator.
	       *  @param  __last   An input iterator.
	       *
	       *  This function fills a %list with copies of the elements in the
	       *  range [@a __first,@a __last).
	       *
	       *  Note that the assignment completely changes the %list and
	       *  that the resulting %list's size is the same as the number of
	       *  elements assigned.  Old data may be lost.
	       */
	#if __cplusplus >= 201103L
	      template<typename _InputIterator,
		       typename = std::_RequireInputIter<_InputIterator>>
	        void
	        assign(_InputIterator __first, _InputIterator __last)
	        { _M_assign_dispatch(__first, __last, __false_type()); }
	#else
	      template<typename _InputIterator>
	        void
	        assign(_InputIterator __first, _InputIterator __last)
	        {
		  // Check whether it's an integral type.  If so, it's not an iterator.
		  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
		  _M_assign_dispatch(__first, __last, _Integral());
		}
	#endif
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  Assigns an initializer_list to a %list.
	       *  @param  __l  An initializer_list of value_type.
	       *
	       *  Replace the contents of the %list with copies of the elements
	       *  in the initializer_list @a __l.  This is linear in __l.size().
	       */
	      void
	      assign(initializer_list<value_type> __l)
	      { this->assign(__l.begin(), __l.end()); }
	#endif
	
	      /// Get a copy of the memory allocation object.
	      allocator_type
	      get_allocator() const _GLIBCXX_NOEXCEPT
	      { return _Base::get_allocator(); }
	
	      // iterators
	      /**
	       *  Returns a read/write iterator that points to the first element in the
	       *  %list.  Iteration is done in ordinary element order.
	       */
	      iterator
	      begin() _GLIBCXX_NOEXCEPT
	      { return iterator(this->_M_impl._M_node._M_next); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points to the
	       *  first element in the %list.  Iteration is done in ordinary
	       *  element order.
	       */
	      const_iterator
	      begin() const _GLIBCXX_NOEXCEPT
	      { return const_iterator(this->_M_impl._M_node._M_next); }
	
	      /**
	       *  Returns a read/write iterator that points one past the last
	       *  element in the %list.  Iteration is done in ordinary element
	       *  order.
	       */
	      iterator
	      end() _GLIBCXX_NOEXCEPT
	      { return iterator(&this->_M_impl._M_node); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points one past
	       *  the last element in the %list.  Iteration is done in ordinary
	       *  element order.
	       */
	      const_iterator
	      end() const _GLIBCXX_NOEXCEPT
	      { return const_iterator(&this->_M_impl._M_node); }
	
	      /**
	       *  Returns a read/write reverse iterator that points to the last
	       *  element in the %list.  Iteration is done in reverse element
	       *  order.
	       */
	      reverse_iterator
	      rbegin() _GLIBCXX_NOEXCEPT
	      { return reverse_iterator(end()); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to
	       *  the last element in the %list.  Iteration is done in reverse
	       *  element order.
	       */
	      const_reverse_iterator
	      rbegin() const _GLIBCXX_NOEXCEPT
	      { return const_reverse_iterator(end()); }
	
	      /**
	       *  Returns a read/write reverse iterator that points to one
	       *  before the first element in the %list.  Iteration is done in
	       *  reverse element order.
	       */
	      reverse_iterator
	      rend() _GLIBCXX_NOEXCEPT
	      { return reverse_iterator(begin()); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to one
	       *  before the first element in the %list.  Iteration is done in reverse
	       *  element order.
	       */
	      const_reverse_iterator
	      rend() const _GLIBCXX_NOEXCEPT
	      { return const_reverse_iterator(begin()); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  Returns a read-only (constant) iterator that points to the
	       *  first element in the %list.  Iteration is done in ordinary
	       *  element order.
	       */
	      const_iterator
	      cbegin() const noexcept
	      { return const_iterator(this->_M_impl._M_node._M_next); }
	
	      /**
	       *  Returns a read-only (constant) iterator that points one past
	       *  the last element in the %list.  Iteration is done in ordinary
	       *  element order.
	       */
	      const_iterator
	      cend() const noexcept
	      { return const_iterator(&this->_M_impl._M_node); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to
	       *  the last element in the %list.  Iteration is done in reverse
	       *  element order.
	       */
	      const_reverse_iterator
	      crbegin() const noexcept
	      { return const_reverse_iterator(end()); }
	
	      /**
	       *  Returns a read-only (constant) reverse iterator that points to one
	       *  before the first element in the %list.  Iteration is done in reverse
	       *  element order.
	       */
	      const_reverse_iterator
	      crend() const noexcept
	      { return const_reverse_iterator(begin()); }
	#endif
	
	      // [23.2.2.2] capacity
	      /**
	       *  Returns true if the %list is empty.  (Thus begin() would equal
	       *  end().)
	       */
	      bool
	      empty() const _GLIBCXX_NOEXCEPT
	      { return this->_M_impl._M_node._M_next == &this->_M_impl._M_node; }
	
	      /**  Returns the number of elements in the %list.  */
	      size_type
	      size() const _GLIBCXX_NOEXCEPT
	      { return std::distance(begin(), end()); }
	
	      /**  Returns the size() of the largest possible %list.  */
	      size_type
	      max_size() const _GLIBCXX_NOEXCEPT
	      { return _M_get_Node_allocator().max_size(); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief Resizes the %list to the specified number of elements.
	       *  @param __new_size Number of elements the %list should contain.
	       *
	       *  This function will %resize the %list to the specified number
	       *  of elements.  If the number is smaller than the %list's
	       *  current size the %list is truncated, otherwise default
	       *  constructed elements are appended.
	       */
	      void
	      resize(size_type __new_size);
	
	      /**
	       *  @brief Resizes the %list to the specified number of elements.
	       *  @param __new_size Number of elements the %list should contain.
	       *  @param __x Data with which new elements should be populated.
	       *
	       *  This function will %resize the %list to the specified number
	       *  of elements.  If the number is smaller than the %list's
	       *  current size the %list is truncated, otherwise the %list is
	       *  extended and new elements are populated with given data.
	       */
	      void
	      resize(size_type __new_size, const value_type& __x);
	#else
	      /**
	       *  @brief Resizes the %list to the specified number of elements.
	       *  @param __new_size Number of elements the %list should contain.
	       *  @param __x Data with which new elements should be populated.
	       *
	       *  This function will %resize the %list to the specified number
	       *  of elements.  If the number is smaller than the %list's
	       *  current size the %list is truncated, otherwise the %list is
	       *  extended and new elements are populated with given data.
	       */
	      void
	      resize(size_type __new_size, value_type __x = value_type());
	#endif
	
	      // element access
	      /**
	       *  Returns a read/write reference to the data at the first
	       *  element of the %list.
	       */
	      reference
	      front()
	      { return *begin(); }
	
	      /**
	       *  Returns a read-only (constant) reference to the data at the first
	       *  element of the %list.
	       */
	      const_reference
	      front() const
	      { return *begin(); }
	
	      /**
	       *  Returns a read/write reference to the data at the last element
	       *  of the %list.
	       */
	      reference
	      back()
	      { 
		iterator __tmp = end();
		--__tmp;
		return *__tmp;
	      }
	
	      /**
	       *  Returns a read-only (constant) reference to the data at the last
	       *  element of the %list.
	       */
	      const_reference
	      back() const
	      { 
		const_iterator __tmp = end();
		--__tmp;
		return *__tmp;
	      }
	
	      // [23.2.2.3] modifiers
	      /**
	       *  @brief  Add data to the front of the %list.
	       *  @param  __x  Data to be added.
	       *
	       *  This is a typical stack operation.  The function creates an
	       *  element at the front of the %list and assigns the given data
	       *  to it.  Due to the nature of a %list this operation can be
	       *  done in constant time, and does not invalidate iterators and
	       *  references.
	       */
	      void
	      push_front(const value_type& __x)
	      { this->_M_insert(begin(), __x); }
	
	#if __cplusplus >= 201103L
	      void
	      push_front(value_type&& __x)
	      { this->_M_insert(begin(), std::move(__x)); }
	
	      template<typename... _Args>
	        void
	        emplace_front(_Args&&... __args)
	        { this->_M_insert(begin(), std::forward<_Args>(__args)...); }
	#endif
	
	      /**
	       *  @brief  Removes first element.
	       *
	       *  This is a typical stack operation.  It shrinks the %list by
	       *  one.  Due to the nature of a %list this operation can be done
	       *  in constant time, and only invalidates iterators/references to
	       *  the element being removed.
	       *
	       *  Note that no data is returned, and if the first element's data
	       *  is needed, it should be retrieved before pop_front() is
	       *  called.
	       */
	      void
	      pop_front()
	      { this->_M_erase(begin()); }
	
	      /**
	       *  @brief  Add data to the end of the %list.
	       *  @param  __x  Data to be added.
	       *
	       *  This is a typical stack operation.  The function creates an
	       *  element at the end of the %list and assigns the given data to
	       *  it.  Due to the nature of a %list this operation can be done
	       *  in constant time, and does not invalidate iterators and
	       *  references.
	       */
	      void
	      push_back(const value_type& __x)
	      { this->_M_insert(end(), __x); }
	
	#if __cplusplus >= 201103L
	      void
	      push_back(value_type&& __x)
	      { this->_M_insert(end(), std::move(__x)); }
	
	      template<typename... _Args>
	        void
	        emplace_back(_Args&&... __args)
	        { this->_M_insert(end(), std::forward<_Args>(__args)...); }
	#endif
	
	      /**
	       *  @brief  Removes last element.
	       *
	       *  This is a typical stack operation.  It shrinks the %list by
	       *  one.  Due to the nature of a %list this operation can be done
	       *  in constant time, and only invalidates iterators/references to
	       *  the element being removed.
	       *
	       *  Note that no data is returned, and if the last element's data
	       *  is needed, it should be retrieved before pop_back() is called.
	       */
	      void
	      pop_back()
	      { this->_M_erase(iterator(this->_M_impl._M_node._M_prev)); }
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  Constructs object in %list before specified iterator.
	       *  @param  __position  A const_iterator into the %list.
	       *  @param  __args  Arguments.
	       *  @return  An iterator that points to the inserted data.
	       *
	       *  This function will insert an object of type T constructed
	       *  with T(std::forward<Args>(args)...) before the specified
	       *  location.  Due to the nature of a %list this operation can
	       *  be done in constant time, and does not invalidate iterators
	       *  and references.
	       */
	      template<typename... _Args>
	        iterator
	        emplace(iterator __position, _Args&&... __args);
	#endif
	
	      /**
	       *  @brief  Inserts given value into %list before specified iterator.
	       *  @param  __position  An iterator into the %list.
	       *  @param  __x  Data to be inserted.
	       *  @return  An iterator that points to the inserted data.
	       *
	       *  This function will insert a copy of the given value before
	       *  the specified location.  Due to the nature of a %list this
	       *  operation can be done in constant time, and does not
	       *  invalidate iterators and references.
	       */
	      iterator
	      insert(iterator __position, const value_type& __x);
	
	#if __cplusplus >= 201103L
	      /**
	       *  @brief  Inserts given rvalue into %list before specified iterator.
	       *  @param  __position  An iterator into the %list.
	       *  @param  __x  Data to be inserted.
	       *  @return  An iterator that points to the inserted data.
	       *
	       *  This function will insert a copy of the given rvalue before
	       *  the specified location.  Due to the nature of a %list this
	       *  operation can be done in constant time, and does not
	       *  invalidate iterators and references.
	        */
	      iterator
	      insert(iterator __position, value_type&& __x)
	      { return emplace(__position, std::move(__x)); }
	
	      /**
	       *  @brief  Inserts the contents of an initializer_list into %list
	       *          before specified iterator.
	       *  @param  __p  An iterator into the %list.
	       *  @param  __l  An initializer_list of value_type.
	       *
	       *  This function will insert copies of the data in the
	       *  initializer_list @a l into the %list before the location
	       *  specified by @a p.
	       *
	       *  This operation is linear in the number of elements inserted and
	       *  does not invalidate iterators and references.
	       */
	      void
	      insert(iterator __p, initializer_list<value_type> __l)
	      { this->insert(__p, __l.begin(), __l.end()); }
	#endif
	
	      /**
	       *  @brief  Inserts a number of copies of given data into the %list.
	       *  @param  __position  An iterator into the %list.
	       *  @param  __n  Number of elements to be inserted.
	       *  @param  __x  Data to be inserted.
	       *
	       *  This function will insert a specified number of copies of the
	       *  given data before the location specified by @a position.
	       *
	       *  This operation is linear in the number of elements inserted and
	       *  does not invalidate iterators and references.
	       */
	      void
	      insert(iterator __position, size_type __n, const value_type& __x)
	      {
		list __tmp(__n, __x, get_allocator());
		splice(__position, __tmp);
	      }
	
	      /**
	       *  @brief  Inserts a range into the %list.
	       *  @param  __position  An iterator into the %list.
	       *  @param  __first  An input iterator.
	       *  @param  __last   An input iterator.
	       *
	       *  This function will insert copies of the data in the range [@a
	       *  first,@a last) into the %list before the location specified by
	       *  @a position.
	       *
	       *  This operation is linear in the number of elements inserted and
	       *  does not invalidate iterators and references.
	       */
	#if __cplusplus >= 201103L
	      template<typename _InputIterator,
		       typename = std::_RequireInputIter<_InputIterator>>
	#else
	      template<typename _InputIterator>
	#endif
	        void
	        insert(iterator __position, _InputIterator __first,
		       _InputIterator __last)
	        {
		  list __tmp(__first, __last, get_allocator());
		  splice(__position, __tmp);
		}
	
	      /**
	       *  @brief  Remove element at given position.
	       *  @param  __position  Iterator pointing to element to be erased.
	       *  @return  An iterator pointing to the next element (or end()).
	       *
	       *  This function will erase the element at the given position and thus
	       *  shorten the %list by one.
	       *
	       *  Due to the nature of a %list this operation can be done in
	       *  constant time, and only invalidates iterators/references to
	       *  the element being removed.  The user is also cautioned that
	       *  this function only erases the element, and that if the element
	       *  is itself a pointer, the pointed-to memory is not touched in
	       *  any way.  Managing the pointer is the user's responsibility.
	       */
	      iterator
	      erase(iterator __position);
	
	      /**
	       *  @brief  Remove a range of elements.
	       *  @param  __first  Iterator pointing to the first element to be erased.
	       *  @param  __last  Iterator pointing to one past the last element to be
	       *                erased.
	       *  @return  An iterator pointing to the element pointed to by @a last
	       *           prior to erasing (or end()).
	       *
	       *  This function will erase the elements in the range @a
	       *  [first,last) and shorten the %list accordingly.
	       *
	       *  This operation is linear time in the size of the range and only
	       *  invalidates iterators/references to the element being removed.
	       *  The user is also cautioned that this function only erases the
	       *  elements, and that if the elements themselves are pointers, the
	       *  pointed-to memory is not touched in any way.  Managing the pointer
	       *  is the user's responsibility.
	       */
	      iterator
	      erase(iterator __first, iterator __last)
	      {
		while (__first != __last)
		  __first = erase(__first);
		return __last;
	      }
	
	      /**
	       *  @brief  Swaps data with another %list.
	       *  @param  __x  A %list of the same element and allocator types.
	       *
	       *  This exchanges the elements between two lists in constant
	       *  time.  Note that the global std::swap() function is
	       *  specialized such that std::swap(l1,l2) will feed to this
	       *  function.
	       */
	      void
	      swap(list& __x)
	      {
		__detail::_List_node_base::swap(this->_M_impl._M_node, 
						__x._M_impl._M_node);
	
		// _GLIBCXX_RESOLVE_LIB_DEFECTS
		// 431. Swapping containers with unequal allocators.
		std::__alloc_swap<typename _Base::_Node_alloc_type>::
		  _S_do_it(_M_get_Node_allocator(), __x._M_get_Node_allocator());
	      }
	
	      /**
	       *  Erases all the elements.  Note that this function only erases
	       *  the elements, and that if the elements themselves are
	       *  pointers, the pointed-to memory is not touched in any way.
	       *  Managing the pointer is the user's responsibility.
	       */
	      void
	      clear() _GLIBCXX_NOEXCEPT
	      {
	        _Base::_M_clear();
	        _Base::_M_init();
	      }
	
	      // [23.2.2.4] list operations
	      /**
	       *  @brief  Insert contents of another %list.
	       *  @param  __position  Iterator referencing the element to insert before.
	       *  @param  __x  Source list.
	       *
	       *  The elements of @a __x are inserted in constant time in front of
	       *  the element referenced by @a __position.  @a __x becomes an empty
	       *  list.
	       *
	       *  Requires this != @a __x.
	       */
	      void
	#if __cplusplus >= 201103L
	      splice(iterator __position, list&& __x)
	#else
	      splice(iterator __position, list& __x)
	#endif
	      {
		if (!__x.empty())
		  {
		    _M_check_equal_allocators(__x);
	
		    this->_M_transfer(__position, __x.begin(), __x.end());
		  }
	      }
	
	#if __cplusplus >= 201103L
	      void
	      splice(iterator __position, list& __x)
	      { splice(__position, std::move(__x)); }
	#endif
	
	      /**
	       *  @brief  Insert element from another %list.
	       *  @param  __position  Iterator referencing the element to insert before.
	       *  @param  __x  Source list.
	       *  @param  __i  Iterator referencing the element to move.
	       *
	       *  Removes the element in list @a __x referenced by @a __i and
	       *  inserts it into the current list before @a __position.
	       */
	      void
	#if __cplusplus >= 201103L
	      splice(iterator __position, list&& __x, iterator __i)
	#else
	      splice(iterator __position, list& __x, iterator __i)
	#endif
	      {
		iterator __j = __i;
		++__j;
		if (__position == __i || __position == __j)
		  return;
	
		if (this != &__x)
		  _M_check_equal_allocators(__x);
	
		this->_M_transfer(__position, __i, __j);
	      }
	
	#if __cplusplus >= 201103L
	      void
	      splice(iterator __position, list& __x, iterator __i)
	      { splice(__position, std::move(__x), __i); }
	#endif
	
	      /**
	       *  @brief  Insert range from another %list.
	       *  @param  __position  Iterator referencing the element to insert before.
	       *  @param  __x  Source list.
	       *  @param  __first  Iterator referencing the start of range in x.
	       *  @param  __last  Iterator referencing the end of range in x.
	       *
	       *  Removes elements in the range [__first,__last) and inserts them
	       *  before @a __position in constant time.
	       *
	       *  Undefined if @a __position is in [__first,__last).
	       */
	      void
	#if __cplusplus >= 201103L
	      splice(iterator __position, list&& __x, iterator __first,
		     iterator __last)
	#else
	      splice(iterator __position, list& __x, iterator __first,
		     iterator __last)
	#endif
	      {
		if (__first != __last)
		  {
		    if (this != &__x)
		      _M_check_equal_allocators(__x);
	
		    this->_M_transfer(__position, __first, __last);
		  }
	      }
	
	#if __cplusplus >= 201103L
	      void
	      splice(iterator __position, list& __x, iterator __first, iterator __last)
	      { splice(__position, std::move(__x), __first, __last); }
	#endif
	
	      /**
	       *  @brief  Remove all elements equal to value.
	       *  @param  __value  The value to remove.
	       *
	       *  Removes every element in the list equal to @a value.
	       *  Remaining elements stay in list order.  Note that this
	       *  function only erases the elements, and that if the elements
	       *  themselves are pointers, the pointed-to memory is not
	       *  touched in any way.  Managing the pointer is the user's
	       *  responsibility.
	       */
	      void
	      remove(const _Tp& __value);
	
	      /**
	       *  @brief  Remove all elements satisfying a predicate.
	       *  @tparam  _Predicate  Unary predicate function or object.
	       *
	       *  Removes every element in the list for which the predicate
	       *  returns true.  Remaining elements stay in list order.  Note
	       *  that this function only erases the elements, and that if the
	       *  elements themselves are pointers, the pointed-to memory is
	       *  not touched in any way.  Managing the pointer is the user's
	       *  responsibility.
	       */
	      template<typename _Predicate>
	        void
	        remove_if(_Predicate);
	
	      /**
	       *  @brief  Remove consecutive duplicate elements.
	       *
	       *  For each consecutive set of elements with the same value,
	       *  remove all but the first one.  Remaining elements stay in
	       *  list order.  Note that this function only erases the
	       *  elements, and that if the elements themselves are pointers,
	       *  the pointed-to memory is not touched in any way.  Managing
	       *  the pointer is the user's responsibility.
	       */
	      void
	      unique();
	
	      /**
	       *  @brief  Remove consecutive elements satisfying a predicate.
	       *  @tparam _BinaryPredicate  Binary predicate function or object.
	       *
	       *  For each consecutive set of elements [first,last) that
	       *  satisfy predicate(first,i) where i is an iterator in
	       *  [first,last), remove all but the first one.  Remaining
	       *  elements stay in list order.  Note that this function only
	       *  erases the elements, and that if the elements themselves are
	       *  pointers, the pointed-to memory is not touched in any way.
	       *  Managing the pointer is the user's responsibility.
	       */
	      template<typename _BinaryPredicate>
	        void
	        unique(_BinaryPredicate);
	
	      /**
	       *  @brief  Merge sorted lists.
	       *  @param  __x  Sorted list to merge.
	       *
	       *  Assumes that both @a __x and this list are sorted according to
	       *  operator<().  Merges elements of @a __x into this list in
	       *  sorted order, leaving @a __x empty when complete.  Elements in
	       *  this list precede elements in @a __x that are equal.
	       */
	#if __cplusplus >= 201103L
	      void
	      merge(list&& __x);
	
	      void
	      merge(list& __x)
	      { merge(std::move(__x)); }
	#else
	      void
	      merge(list& __x);
	#endif
	
	      /**
	       *  @brief  Merge sorted lists according to comparison function.
	       *  @tparam _StrictWeakOrdering Comparison function defining
	       *  sort order.
	       *  @param  __x  Sorted list to merge.
	       *  @param  __comp  Comparison functor.
	       *
	       *  Assumes that both @a __x and this list are sorted according to
	       *  StrictWeakOrdering.  Merges elements of @a __x into this list
	       *  in sorted order, leaving @a __x empty when complete.  Elements
	       *  in this list precede elements in @a __x that are equivalent
	       *  according to StrictWeakOrdering().
	       */
	#if __cplusplus >= 201103L
	      template<typename _StrictWeakOrdering>
	        void
	        merge(list&& __x, _StrictWeakOrdering __comp);
	
	      template<typename _StrictWeakOrdering>
	        void
	        merge(list& __x, _StrictWeakOrdering __comp)
	        { merge(std::move(__x), __comp); }
	#else
	      template<typename _StrictWeakOrdering>
	        void
	        merge(list& __x, _StrictWeakOrdering __comp);
	#endif
	
	      /**
	       *  @brief  Reverse the elements in list.
	       *
	       *  Reverse the order of elements in the list in linear time.
	       */
	      void
	      reverse() _GLIBCXX_NOEXCEPT
	      { this->_M_impl._M_node._M_reverse(); }
	
	      /**
	       *  @brief  Sort the elements.
	       *
	       *  Sorts the elements of this list in NlogN time.  Equivalent
	       *  elements remain in list order.
	       */
	      void
	      sort();
	
	      /**
	       *  @brief  Sort the elements according to comparison function.
	       *
	       *  Sorts the elements of this list in NlogN time.  Equivalent
	       *  elements remain in list order.
	       */
	      template<typename _StrictWeakOrdering>
	        void
	        sort(_StrictWeakOrdering);
	
	    protected:
	      // Internal constructor functions follow.
	
	      // Called by the range constructor to implement [23.1.1]/9
	
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // 438. Ambiguity in the "do the right thing" clause
	      template<typename _Integer>
	        void
	        _M_initialize_dispatch(_Integer __n, _Integer __x, __true_type)
	        { _M_fill_initialize(static_cast<size_type>(__n), __x); }
	
	      // Called by the range constructor to implement [23.1.1]/9
	      template<typename _InputIterator>
	        void
	        _M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
				       __false_type)
	        {
		  for (; __first != __last; ++__first)
	#if __cplusplus >= 201103L
		    emplace_back(*__first);
	#else
		    push_back(*__first);
	#endif
		}
	
	      // Called by list(n,v,a), and the range constructor when it turns out
	      // to be the same thing.
	      void
	      _M_fill_initialize(size_type __n, const value_type& __x)
	      {
		for (; __n; --__n)
		  push_back(__x);
	      }
	
	#if __cplusplus >= 201103L
	      // Called by list(n).
	      void
	      _M_default_initialize(size_type __n)
	      {
		for (; __n; --__n)
		  emplace_back();
	      }
	
	      // Called by resize(sz).
	      void
	      _M_default_append(size_type __n);
	#endif
	
	      // Internal assign functions follow.
	
	      // Called by the range assign to implement [23.1.1]/9
	
	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
	      // 438. Ambiguity in the "do the right thing" clause
	      template<typename _Integer>
	        void
	        _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
	        { _M_fill_assign(__n, __val); }
	
	      // Called by the range assign to implement [23.1.1]/9
	      template<typename _InputIterator>
	        void
	        _M_assign_dispatch(_InputIterator __first, _InputIterator __last,
				   __false_type);
	
	      // Called by assign(n,t), and the range assign when it turns out
	      // to be the same thing.
	      void
	      _M_fill_assign(size_type __n, const value_type& __val);
	
	
	      // Moves the elements from [first,last) before position.
	      void
	      _M_transfer(iterator __position, iterator __first, iterator __last)
	      { __position._M_node->_M_transfer(__first._M_node, __last._M_node); }
	
	      // Inserts new element at position given and with value given.
	#if __cplusplus < 201103L
	      void
	      _M_insert(iterator __position, const value_type& __x)
	      {
	        _Node* __tmp = _M_create_node(__x);
	        __tmp->_M_hook(__position._M_node);
	      }
	#else
	     template<typename... _Args>
	       void
	       _M_insert(iterator __position, _Args&&... __args)
	       {
		 _Node* __tmp = _M_create_node(std::forward<_Args>(__args)...);
		 __tmp->_M_hook(__position._M_node);
	       }
	#endif
	
	      // Erases element at position given.
	      void
	      _M_erase(iterator __position)
	      {
	        __position._M_node->_M_unhook();
	        _Node* __n = static_cast<_Node*>(__position._M_node);
	#if __cplusplus >= 201103L
	        _M_get_Node_allocator().destroy(__n);
	#else
		_M_get_Tp_allocator().destroy(std::__addressof(__n->_M_data));
	#endif
	        _M_put_node(__n);
	      }
	
	      // To implement the splice (and merge) bits of N1599.
	      void
	      _M_check_equal_allocators(list& __x)
	      {
		if (std::__alloc_neq<typename _Base::_Node_alloc_type>::
		    _S_do_it(_M_get_Node_allocator(), __x._M_get_Node_allocator()))
		  __throw_runtime_error(__N("list::_M_check_equal_allocators"));
	      }
	    };
	
	  /**
	   *  @brief  List equality comparison.
	   *  @param  __x  A %list.
	   *  @param  __y  A %list of the same type as @a __x.
	   *  @return  True iff the size and elements of the lists are equal.
	   *
	   *  This is an equivalence relation.  It is linear in the size of
	   *  the lists.  Lists are considered equivalent if their sizes are
	   *  equal, and if corresponding elements compare equal.
	  */
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator==(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    {
	      typedef typename list<_Tp, _Alloc>::const_iterator const_iterator;
	      const_iterator __end1 = __x.end();
	      const_iterator __end2 = __y.end();
	
	      const_iterator __i1 = __x.begin();
	      const_iterator __i2 = __y.begin();
	      while (__i1 != __end1 && __i2 != __end2 && *__i1 == *__i2)
		{
		  ++__i1;
		  ++__i2;
		}
	      return __i1 == __end1 && __i2 == __end2;
	    }
	
	  /**
	   *  @brief  List ordering relation.
	   *  @param  __x  A %list.
	   *  @param  __y  A %list of the same type as @a __x.
	   *  @return  True iff @a __x is lexicographically less than @a __y.
	   *
	   *  This is a total ordering relation.  It is linear in the size of the
	   *  lists.  The elements must be comparable with @c <.
	   *
	   *  See std::lexicographical_compare() for how the determination is made.
	  */
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator<(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    { return std::lexicographical_compare(__x.begin(), __x.end(),
						  __y.begin(), __y.end()); }
	
	  /// Based on operator==
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator!=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    { return !(__x == __y); }
	
	  /// Based on operator<
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator>(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    { return __y < __x; }
	
	  /// Based on operator<
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator<=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    { return !(__y < __x); }
	
	  /// Based on operator<
	  template<typename _Tp, typename _Alloc>
	    inline bool
	    operator>=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
	    { return !(__x < __y); }
	
	  /// See std::list::swap().
	  template<typename _Tp, typename _Alloc>
	    inline void
	    swap(list<_Tp, _Alloc>& __x, list<_Tp, _Alloc>& __y)
	    { __x.swap(__y); }
	
	_GLIBCXX_END_NAMESPACE_CONTAINER
	} // namespace std
	
	#endif /* _STL_LIST_H */