// -*- C++ -*-
//===---------------------------- list ------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_LIST
#define _LIBCPP_LIST

/*
    list synopsis

namespace std
{

template <class T, class Alloc = allocator<T> >
class list
{
public:

    // types:
    typedef T value_type;
    typedef Alloc allocator_type;
    typedef typename allocator_type::reference reference;
    typedef typename allocator_type::const_reference const_reference;
    typedef typename allocator_type::pointer pointer;
    typedef typename allocator_type::const_pointer const_pointer;
    typedef implementation-defined iterator;
    typedef implementation-defined const_iterator;
    typedef implementation-defined size_type;
    typedef implementation-defined difference_type;
    typedef reverse_iterator<iterator> reverse_iterator;
    typedef reverse_iterator<const_iterator> const_reverse_iterator;

    list()
        noexcept(is_nothrow_default_constructible<allocator_type>::value);
    explicit list(const allocator_type& a);
    explicit list(size_type n);
    list(size_type n, const value_type& value);
    list(size_type n, const value_type& value, const allocator_type& a);
    template <class Iter>
        list(Iter first, Iter last);
    template <class Iter>
        list(Iter first, Iter last, const allocator_type& a);
    list(const list& x);
    list(const list&, const allocator_type& a);
    list(list&& x)
        noexcept(is_nothrow_move_constructible<allocator_type>::value);
    list(list&&, const allocator_type& a);
    list(initializer_list<value_type>);
    list(initializer_list<value_type>, const allocator_type& a);

    ~list();

    list& operator=(const list& x);
    list& operator=(list&& x)
        noexcept(
             allocator_type::propagate_on_container_move_assignment::value &&
             is_nothrow_move_assignable<allocator_type>::value);
    list& operator=(initializer_list<value_type>);
    template <class Iter>
        void assign(Iter first, Iter last);
    void assign(size_type n, const value_type& t);
    void assign(initializer_list<value_type>);

    allocator_type get_allocator() const noexcept;

    iterator begin() noexcept;
    const_iterator begin() const noexcept;
    iterator end() noexcept;
    const_iterator end() const noexcept;
    reverse_iterator rbegin() noexcept;
    const_reverse_iterator rbegin() const noexcept;
    reverse_iterator rend() noexcept;
    const_reverse_iterator rend() const noexcept;
    const_iterator cbegin() const noexcept;
    const_iterator cend() const noexcept;
    const_reverse_iterator crbegin() const noexcept;
    const_reverse_iterator crend() const noexcept;

    reference front();
    const_reference front() const;
    reference back();
    const_reference back() const;

    bool empty() const noexcept;
    size_type size() const noexcept;
    size_type max_size() const noexcept;

    template <class... Args>
        void emplace_front(Args&&... args);
    void pop_front();
    template <class... Args>
        void emplace_back(Args&&... args);
    void pop_back();
    void push_front(const value_type& x);
    void push_front(value_type&& x);
    void push_back(const value_type& x);
    void push_back(value_type&& x);
    template <class... Args>
        iterator emplace(const_iterator position, Args&&... args);
    iterator insert(const_iterator position, const value_type& x);
    iterator insert(const_iterator position, value_type&& x);
    iterator insert(const_iterator position, size_type n, const value_type& x);
    template <class Iter>
        iterator insert(const_iterator position, Iter first, Iter last);
    iterator insert(const_iterator position, initializer_list<value_type> il);

    iterator erase(const_iterator position);
    iterator erase(const_iterator position, const_iterator last);

    void resize(size_type sz);
    void resize(size_type sz, const value_type& c);

    void swap(list&)
        noexcept(!allocator_type::propagate_on_container_swap::value ||
                 __is_nothrow_swappable<allocator_type>::value);
    void clear() noexcept;

    void splice(const_iterator position, list& x);
    void splice(const_iterator position, list&& x);
    void splice(const_iterator position, list& x, const_iterator i);
    void splice(const_iterator position, list&& x, const_iterator i);
    void splice(const_iterator position, list& x, const_iterator first,
                                                  const_iterator last);
    void splice(const_iterator position, list&& x, const_iterator first,
                                                  const_iterator last);

    void remove(const value_type& value);
    template <class Pred> void remove_if(Pred pred);
    void unique();
    template <class BinaryPredicate>
        void unique(BinaryPredicate binary_pred);
    void merge(list& x);
    void merge(list&& x);
    template <class Compare>
        void merge(list& x, Compare comp);
    template <class Compare>
        void merge(list&& x, Compare comp);
    void sort();
    template <class Compare>
        void sort(Compare comp);
    void reverse() noexcept;
};

template <class T, class Alloc>
    bool operator==(const list<T,Alloc>& x, const list<T,Alloc>& y);
template <class T, class Alloc>
    bool operator< (const list<T,Alloc>& x, const list<T,Alloc>& y);
template <class T, class Alloc>
    bool operator!=(const list<T,Alloc>& x, const list<T,Alloc>& y);
template <class T, class Alloc>
    bool operator> (const list<T,Alloc>& x, const list<T,Alloc>& y);
template <class T, class Alloc>
    bool operator>=(const list<T,Alloc>& x, const list<T,Alloc>& y);
template <class T, class Alloc>
    bool operator<=(const list<T,Alloc>& x, const list<T,Alloc>& y);

template <class T, class Alloc>
    void swap(list<T,Alloc>& x, list<T,Alloc>& y)
         noexcept(noexcept(x.swap(y)));

}  // std

*/

#include <__config>

#include <memory>
#include <limits>
#include <initializer_list>
#include <iterator>
#include <algorithm>

#pragma GCC system_header

_LIBCPP_BEGIN_NAMESPACE_STD

template <class, class> struct __list_node;

template <class _Tp, class _VoidPtr>
struct __list_node_base
{
    typedef typename pointer_traits<_VoidPtr>::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
        rebind<__list_node<_Tp, _VoidPtr> > pointer;
#else
        rebind<__list_node<_Tp, _VoidPtr> >::other pointer;
#endif

    pointer __prev_;
    pointer __next_;

    _LIBCPP_INLINE_VISIBILITY
    __list_node_base()
        : __prev_(static_cast<pointer>(this)),
          __next_(static_cast<pointer>(this))
          {}
};

template <class _Tp, class _VoidPtr>
struct __list_node
    : public __list_node_base<_Tp, _VoidPtr>
{
    _Tp __value_;
};

template <class, class> class list;
template <class, class> class __list_imp;
template <class, class> class __list_const_iterator;

template <class _Tp, class _VoidPtr>
class _LIBCPP_VISIBLE __list_iterator
{
    typedef typename pointer_traits<_VoidPtr>::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
        rebind<__list_node<_Tp, _VoidPtr> > __node_pointer;
#else
        rebind<__list_node<_Tp, _VoidPtr> >::other __node_pointer;
#endif

    __node_pointer __ptr_;

    _LIBCPP_INLINE_VISIBILITY
    explicit __list_iterator(__node_pointer __p) _NOEXCEPT : __ptr_(__p) {}

    template<class, class> friend class list;
    template<class, class> friend class __list_imp;
    template<class, class> friend class __list_const_iterator;
public:
    typedef bidirectional_iterator_tag       iterator_category;
    typedef _Tp                              value_type;
    typedef value_type&                      reference;
    typedef typename pointer_traits<_VoidPtr>::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
            rebind<value_type>
#else
            rebind<value_type>::other
#endif
                                             pointer;
    typedef typename pointer_traits<pointer>::difference_type difference_type;

    _LIBCPP_INLINE_VISIBILITY
    __list_iterator() _NOEXCEPT {}
    _LIBCPP_INLINE_VISIBILITY
    reference operator*() const {return __ptr_->__value_;}
    _LIBCPP_INLINE_VISIBILITY
    pointer operator->() const {return &(operator*());}

    _LIBCPP_INLINE_VISIBILITY
    __list_iterator& operator++() {__ptr_ = __ptr_->__next_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __list_iterator operator++(int) {__list_iterator __t(*this); ++(*this); return __t;}

    _LIBCPP_INLINE_VISIBILITY
    __list_iterator& operator--() {__ptr_ = __ptr_->__prev_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __list_iterator operator--(int) {__list_iterator __t(*this); --(*this); return __t;}

    friend _LIBCPP_INLINE_VISIBILITY
    bool operator==(const __list_iterator& __x, const __list_iterator& __y)
        {return __x.__ptr_ == __y.__ptr_;}
    friend _LIBCPP_INLINE_VISIBILITY
     bool operator!=(const __list_iterator& __x, const __list_iterator& __y)
        {return !(__x == __y);}
};

template <class _Tp, class _VoidPtr>
class _LIBCPP_VISIBLE __list_const_iterator
{
    typedef typename pointer_traits<_VoidPtr>::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
        rebind<const __list_node<_Tp, _VoidPtr> > __node_pointer;
#else
        rebind<const __list_node<_Tp, _VoidPtr> >::other __node_pointer;
#endif

    __node_pointer __ptr_;

    _LIBCPP_INLINE_VISIBILITY
    explicit __list_const_iterator(__node_pointer __p) _NOEXCEPT : __ptr_(__p) {}

    template<class, class> friend class list;
    template<class, class> friend class __list_imp;
public:
    typedef bidirectional_iterator_tag       iterator_category;
    typedef _Tp                              value_type;
    typedef const value_type&                reference;
    typedef typename pointer_traits<_VoidPtr>::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
            rebind<const value_type>
#else
            rebind<const value_type>::other
#endif
                                             pointer;
    typedef typename pointer_traits<pointer>::difference_type difference_type;

    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator() _NOEXCEPT {}
    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator(__list_iterator<_Tp, _VoidPtr> __p) _NOEXCEPT
        : __ptr_(__p.__ptr_) {}

    _LIBCPP_INLINE_VISIBILITY
    reference operator*() const {return __ptr_->__value_;}
    _LIBCPP_INLINE_VISIBILITY
    pointer operator->() const {return &(operator*());}

    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator& operator++() {__ptr_ = __ptr_->__next_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator operator++(int) {__list_const_iterator __t(*this); ++(*this); return __t;}

    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator& operator--() {__ptr_ = __ptr_->__prev_; return *this;}
    _LIBCPP_INLINE_VISIBILITY
    __list_const_iterator operator--(int) {__list_const_iterator __t(*this); --(*this); return __t;}

    friend _LIBCPP_INLINE_VISIBILITY
    bool operator==(const __list_const_iterator& __x, const __list_const_iterator& __y)
        {return __x.__ptr_ == __y.__ptr_;}
    friend _LIBCPP_INLINE_VISIBILITY
    bool operator!=(const __list_const_iterator& __x, const __list_const_iterator& __y)
        {return !(__x == __y);}
};

template <class _Tp, class _Alloc>
class __list_imp
{
    __list_imp(const __list_imp&);
    __list_imp& operator=(const __list_imp&);
protected:
    typedef _Tp                                                     value_type;
    typedef _Alloc                                                  allocator_type;
    typedef allocator_traits<allocator_type>                        __alloc_traits;
    typedef typename __alloc_traits::size_type                      size_type;
    typedef typename __alloc_traits::void_pointer                   __void_pointer;
    typedef __list_iterator<value_type, __void_pointer>             iterator;
    typedef __list_const_iterator<value_type, __void_pointer>       const_iterator;
    typedef __list_node_base<value_type, __void_pointer>            __node_base;
    typedef __list_node<value_type, __void_pointer>                 __node;
    typedef typename __alloc_traits::template
#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
                rebind_alloc<__node>
#else
                rebind_alloc<__node>::other
#endif
                                                                     __node_allocator;
    typedef allocator_traits<__node_allocator>                       __node_alloc_traits;
    typedef typename __node_alloc_traits::pointer                    __node_pointer;
    typedef typename __node_alloc_traits::const_pointer              __node_const_pointer;
    typedef typename __alloc_traits::pointer                         pointer;
    typedef typename __alloc_traits::const_pointer                   const_pointer;
    typedef typename __alloc_traits::difference_type                 difference_type;

    __node_base __end_;
    __compressed_pair<size_type, __node_allocator> __size_alloc_;

    _LIBCPP_INLINE_VISIBILITY
          size_type& __sz() _NOEXCEPT {return __size_alloc_.first();}
    _LIBCPP_INLINE_VISIBILITY
    const size_type& __sz() const _NOEXCEPT
        {return __size_alloc_.first();}
    _LIBCPP_INLINE_VISIBILITY
          __node_allocator& __node_alloc() _NOEXCEPT
          {return __size_alloc_.second();}
    _LIBCPP_INLINE_VISIBILITY
    const __node_allocator& __node_alloc() const _NOEXCEPT
        {return __size_alloc_.second();}

    static void __unlink_nodes(__node_base& __f, __node_base& __l) _NOEXCEPT;

    __list_imp()
        _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value);
    __list_imp(const allocator_type& __a);
    ~__list_imp();
    void clear() _NOEXCEPT;
    _LIBCPP_INLINE_VISIBILITY
    bool empty() const _NOEXCEPT {return __sz() == 0;}

    _LIBCPP_INLINE_VISIBILITY
          iterator begin() _NOEXCEPT
            {return       iterator(__end_.__next_);}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator begin() const  _NOEXCEPT
        {return const_iterator(__end_.__next_);}
    _LIBCPP_INLINE_VISIBILITY
          iterator end() _NOEXCEPT
            {return       iterator(static_cast<__node_pointer>      (&__end_));}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator end() const _NOEXCEPT
        {return const_iterator(static_cast<__node_const_pointer>(&__end_));}

    void swap(__list_imp& __c)
        _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_swap::value ||
                   __is_nothrow_swappable<__node_allocator>::value);

    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __list_imp& __c)
        {__copy_assign_alloc(__c, integral_constant<bool,
                      __node_alloc_traits::propagate_on_container_copy_assignment::value>());}

    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(__list_imp& __c)
        _NOEXCEPT_(
            !__node_alloc_traits::propagate_on_container_move_assignment::value ||
            is_nothrow_move_assignable<__node_allocator>::value)
        {__move_assign_alloc(__c, integral_constant<bool,
                      __node_alloc_traits::propagate_on_container_move_assignment::value>());}

private:
    _LIBCPP_INLINE_VISIBILITY
    static void __swap_alloc(__node_allocator& __x, __node_allocator& __y)
        _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_swap::value ||
                   __is_nothrow_swappable<__node_allocator>::value)
        {__swap_alloc(__x, __y, integral_constant<bool,
                      __node_alloc_traits::propagate_on_container_swap::value>());}
    _LIBCPP_INLINE_VISIBILITY
    static void __swap_alloc(__node_allocator& __x, __node_allocator& __y, true_type)
        _NOEXCEPT_(__is_nothrow_swappable<__node_allocator>::value)
        {
            using _STD::swap;
            swap(__x, __y);
        }
    _LIBCPP_INLINE_VISIBILITY
    static void __swap_alloc(__node_allocator& __x, __node_allocator& __y, false_type)
        _NOEXCEPT
        {}

    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __list_imp& __c, true_type)
        {
            if (__node_alloc() != __c.__node_alloc())
                clear();
            __node_alloc() = __c.__node_alloc();
        }

    _LIBCPP_INLINE_VISIBILITY
    void __copy_assign_alloc(const __list_imp& __c, false_type)
        {}

    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(const __list_imp& __c, true_type)
        _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value)
        {
            __node_alloc() = _STD::move(__c.__node_alloc());
        }

    _LIBCPP_INLINE_VISIBILITY
    void __move_assign_alloc(const __list_imp& __c, false_type)
        _NOEXCEPT
        {}
};

// Unlink nodes [__f, __l]
template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
__list_imp<_Tp, _Alloc>::__unlink_nodes(__node_base& __f, __node_base& __l)
    _NOEXCEPT
{
    __f.__prev_->__next_ = __l.__next_;
    __l.__next_->__prev_ = __f.__prev_;
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
__list_imp<_Tp, _Alloc>::__list_imp()
        _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value)
    : __size_alloc_(0)
{
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
__list_imp<_Tp, _Alloc>::__list_imp(const allocator_type& __a)
    : __size_alloc_(0, __node_allocator(__a))
{
}

template <class _Tp, class _Alloc>
__list_imp<_Tp, _Alloc>::~__list_imp()
{
    clear();
}

template <class _Tp, class _Alloc>
void
__list_imp<_Tp, _Alloc>::clear() _NOEXCEPT
{
    if (!empty())
    {
        __node_allocator& __na = __node_alloc();
        iterator __f = begin();
        iterator __l = end();
        __unlink_nodes(*__f.__ptr_, *__l.__ptr_->__prev_);
        __sz() = 0;
        while (__f != __l)
        {
            __node& __n = *__f.__ptr_;
            ++__f;
            __node_alloc_traits::destroy(__na, _STD::addressof(__n.__value_));
            __node_alloc_traits::deallocate(__na, _STD::addressof(__n), 1);
        }
    }
}

template <class _Tp, class _Alloc>
void
__list_imp<_Tp, _Alloc>::swap(__list_imp& __c)
        _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_swap::value ||
                   __is_nothrow_swappable<__node_allocator>::value)
{
    using _STD::swap;
    __swap_alloc(__node_alloc(), __c.__node_alloc());
    swap(__sz(), __c.__sz());
    swap(__end_, __c.__end_);
    if (__sz() == 0)
        __end_.__next_ = __end_.__prev_ = &static_cast<__node&>(__end_);
    else
        __end_.__prev_->__next_ = __end_.__next_->__prev_
                                = &static_cast<__node&>(__end_);
    if (__c.__sz() == 0)
        __c.__end_.__next_ = __c.__end_.__prev_
                           = &static_cast<__node&>(__c.__end_);
    else
        __c.__end_.__prev_->__next_ = __c.__end_.__next_->__prev_
                                    = &static_cast<__node&>(__c.__end_);
}

template <class _Tp, class _Alloc = allocator<_Tp> >
class _LIBCPP_VISIBLE list
    : private __list_imp<_Tp, _Alloc>
{
    typedef __list_imp<_Tp, _Alloc> base;
    typedef typename base::__node              __node;
    typedef typename base::__node_allocator    __node_allocator;
    typedef typename base::__node_pointer      __node_pointer;
    typedef typename base::__node_alloc_traits __node_alloc_traits;

public:
    typedef _Tp                                      value_type;
    typedef _Alloc                                   allocator_type;
    static_assert((is_same<value_type, typename allocator_type::value_type>::value),
                  "Invalid allocator::value_type");
    typedef value_type&                              reference;
    typedef const value_type&                        const_reference;
    typedef typename base::pointer                   pointer;
    typedef typename base::const_pointer             const_pointer;
    typedef typename base::size_type                 size_type;
    typedef typename base::difference_type           difference_type;
    typedef typename base::iterator                  iterator;
    typedef typename base::const_iterator            const_iterator;
    typedef _STD::reverse_iterator<iterator>         reverse_iterator;
    typedef _STD::reverse_iterator<const_iterator>   const_reverse_iterator;

    _LIBCPP_INLINE_VISIBILITY
    list()
        _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value)
        {}
    _LIBCPP_INLINE_VISIBILITY
    list(const allocator_type& __a) : base(__a) {}
    list(size_type __n);
    list(size_type __n, const value_type& __x);
    list(size_type __n, const value_type& __x, const allocator_type& __a);
    template <class _InpIter>
        list(_InpIter __f, _InpIter __l,
             typename enable_if<__is_input_iterator<_InpIter>::value>::type* = 0);
    template <class _InpIter>
        list(_InpIter __f, _InpIter __l, const allocator_type& __a,
             typename enable_if<__is_input_iterator<_InpIter>::value>::type* = 0);

    list(const list& __c);
    list(const list& __c, const allocator_type& __a);
    list& operator=(const list& __c);
    list(initializer_list<value_type> __il);
    list(initializer_list<value_type> __il, const allocator_type& __a);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    list(list&& __c)
        _NOEXCEPT_(is_nothrow_move_constructible<__node_allocator>::value);
    list(list&& __c, const allocator_type& __a);
    list& operator=(list&& __c)
        _NOEXCEPT_(
            __node_alloc_traits::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<__node_allocator>::value);
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    _LIBCPP_INLINE_VISIBILITY
    list& operator=(initializer_list<value_type> __il)
        {assign(__il.begin(), __il.end()); return *this;}

    template <class _InpIter>
        void assign(_InpIter __f, _InpIter __l,
             typename enable_if<__is_input_iterator<_InpIter>::value>::type* = 0);
    void assign(size_type __n, const value_type& __x);
    _LIBCPP_INLINE_VISIBILITY
    void assign(initializer_list<value_type> __il)
        {assign(__il.begin(), __il.end());}

    allocator_type get_allocator() const _NOEXCEPT;

    _LIBCPP_INLINE_VISIBILITY
    size_type size() const _NOEXCEPT     {return base::__sz();}
    _LIBCPP_INLINE_VISIBILITY
    bool empty() const _NOEXCEPT         {return base::empty();}
    _LIBCPP_INLINE_VISIBILITY
    size_type max_size() const _NOEXCEPT
        {return numeric_limits<difference_type>::max();}

    _LIBCPP_INLINE_VISIBILITY
          iterator begin() _NOEXCEPT        {return base::begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator begin()  const _NOEXCEPT {return base::begin();}
    _LIBCPP_INLINE_VISIBILITY
          iterator end() _NOEXCEPT          {return base::end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator end()    const _NOEXCEPT {return base::end();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cbegin() const _NOEXCEPT {return base::begin();}
    _LIBCPP_INLINE_VISIBILITY
    const_iterator cend()   const _NOEXCEPT {return base::end();}

    _LIBCPP_INLINE_VISIBILITY
          reverse_iterator rbegin() _NOEXCEPT
            {return       reverse_iterator(end());}
    _LIBCPP_INLINE_VISIBILITY
    const_reverse_iterator rbegin()  const _NOEXCEPT
        {return const_reverse_iterator(end());}
    _LIBCPP_INLINE_VISIBILITY
          reverse_iterator rend() _NOEXCEPT
            {return       reverse_iterator(begin());}
    _LIBCPP_INLINE_VISIBILITY
    const_reverse_iterator rend()    const _NOEXCEPT
        {return const_reverse_iterator(begin());}
    _LIBCPP_INLINE_VISIBILITY
    const_reverse_iterator crbegin() const _NOEXCEPT
        {return const_reverse_iterator(end());}
    _LIBCPP_INLINE_VISIBILITY
    const_reverse_iterator crend()   const _NOEXCEPT
        {return const_reverse_iterator(begin());}

    _LIBCPP_INLINE_VISIBILITY
          reference front()        {return base::__end_.__next_->__value_;}
    _LIBCPP_INLINE_VISIBILITY
    const_reference front() const  {return base::__end_.__next_->__value_;}
    _LIBCPP_INLINE_VISIBILITY
          reference back()         {return base::__end_.__prev_->__value_;}
    _LIBCPP_INLINE_VISIBILITY
    const_reference back()  const  {return base::__end_.__prev_->__value_;}

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    void push_front(value_type&& __x);
    void push_back(value_type&& __x);
#ifndef _LIBCPP_HAS_NO_VARIADICS
    template <class... _Args>
       void emplace_front(_Args&&... __args);
    template <class... _Args>
        void emplace_back(_Args&&... __args);
    template <class... _Args>
        iterator emplace(const_iterator __p, _Args&&... __args);
#endif  // _LIBCPP_HAS_NO_VARIADICS
    iterator insert(const_iterator __p, value_type&& __x);
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES

    void push_front(const value_type& __x);
    void push_back(const value_type& __x);

    iterator insert(const_iterator __p, const value_type& __x);
    iterator insert(const_iterator __p, size_type __n, const value_type& __x);
    template <class _InpIter>
        iterator insert(const_iterator __p, _InpIter __f, _InpIter __l,
             typename enable_if<__is_input_iterator<_InpIter>::value>::type* = 0);
    _LIBCPP_INLINE_VISIBILITY
    iterator insert(const_iterator __p, initializer_list<value_type> __il)
        {return insert(__p, __il.begin(), __il.end());}

    _LIBCPP_INLINE_VISIBILITY
    void swap(list& __c)
        _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_swap::value ||
                   __is_nothrow_swappable<__node_allocator>::value)
        {base::swap(__c);}
    _LIBCPP_INLINE_VISIBILITY
    void clear() _NOEXCEPT {base::clear();}

    void pop_front();
    void pop_back();

    iterator erase(const_iterator __p);
    iterator erase(const_iterator __f, const_iterator __l);

    void resize(size_type __n);
    void resize(size_type __n, const value_type& __x);

    void splice(const_iterator __p, list& __c);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    _LIBCPP_INLINE_VISIBILITY
    void splice(const_iterator __p, list&& __c) {splice(__p, __c);}
#endif
    void splice(const_iterator __p, list& __c, const_iterator __i);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    _LIBCPP_INLINE_VISIBILITY
    void splice(const_iterator __p, list&& __c, const_iterator __i)
        {splice(__p, __c, __i);}
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    void splice(const_iterator __p, list& __c, const_iterator __f, const_iterator __l);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    _LIBCPP_INLINE_VISIBILITY
    void splice(const_iterator __p, list&& __c, const_iterator __f, const_iterator __l)
        {splice(__p, __c, __f, __l);}
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES

    void remove(const value_type& __x);
    template <class _Pred> void remove_if(_Pred __pred);
    void unique();
    template <class _BinaryPred>
        void unique(_BinaryPred __binary_pred);
    void merge(list& __c);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    _LIBCPP_INLINE_VISIBILITY
    void merge(list&& __c) {merge(__c);}
#endif
    template <class _Comp>
        void merge(list& __c, _Comp __comp);
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    template <class _Comp>
    _LIBCPP_INLINE_VISIBILITY
        void merge(list&& __c, _Comp __comp) {merge(__c, __comp);}
#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    void sort();
    template <class _Comp>
        void sort(_Comp __comp);

    void reverse() _NOEXCEPT;

private:
    static void __link_nodes(__node& __p, __node& __f, __node& __l);
    iterator __iterator(size_type __n);
    template <class _Comp>
        static iterator __sort(iterator __f1, iterator __e2, size_type __n, _Comp& __comp);

    void __move_assign(list& __c, true_type)
        _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value);
    void __move_assign(list& __c, false_type);
};

// Link in nodes [__f, __l] just prior to __p
template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
list<_Tp, _Alloc>::__link_nodes(__node& __p, __node& __f, __node& __l)
{
    __p.__prev_->__next_ = &__f;
    __f.__prev_ = __p.__prev_;
    __p.__prev_ = &__l;
    __l.__next_ = &__p;
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::__iterator(size_type __n)
{
    return __n <= base::__sz() / 2 ? _STD::next(begin(), __n)
                                   : _STD::prev(end(), base::__sz() - __n);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(size_type __n)
{
    for (; __n > 0; --__n)
#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
        emplace_back();
#else
        push_back(value_type());
#endif
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(size_type __n, const value_type& __x)
{
    for (; __n > 0; --__n)
        push_back(__x);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(size_type __n, const value_type& __x, const allocator_type& __a)
    : base(__a)
{
    for (; __n > 0; --__n)
        push_back(__x);
}

template <class _Tp, class _Alloc>
template <class _InpIter>
list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l,
                        typename enable_if<__is_input_iterator<_InpIter>::value>::type*)
{
    for (; __f != __l; ++__f)
        push_back(*__f);
}

template <class _Tp, class _Alloc>
template <class _InpIter>
list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l, const allocator_type& __a,
                        typename enable_if<__is_input_iterator<_InpIter>::value>::type*)
    : base(__a)
{
    for (; __f != __l; ++__f)
        push_back(*__f);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(const list& __c)
    : base(allocator_type(
           __node_alloc_traits::select_on_container_copy_construction(
                __c.__node_alloc())))
{
    for (const_iterator __i = __c.begin(), __e = __c.end(); __i != __e; ++__i)
        push_back(*__i);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(const list& __c, const allocator_type& __a)
    : base(__a)
{
    for (const_iterator __i = __c.begin(), __e = __c.end(); __i != __e; ++__i)
        push_back(*__i);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(initializer_list<value_type> __il, const allocator_type& __a)
    : base(__a)
{
    for (typename initializer_list<value_type>::const_iterator __i = __il.begin(),
            __e = __il.end(); __i != __e; ++__i)
        push_back(*__i);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>::list(initializer_list<value_type> __il)
{
    for (typename initializer_list<value_type>::const_iterator __i = __il.begin(),
            __e = __il.end(); __i != __e; ++__i)
        push_back(*__i);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
list<_Tp, _Alloc>&
list<_Tp, _Alloc>::operator=(const list& __c)
{
    if (this != &__c)
    {
        base::__copy_assign_alloc(__c);
        assign(__c.begin(), __c.end());
    }
    return *this;
}

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
list<_Tp, _Alloc>::list(list&& __c)
    _NOEXCEPT_(is_nothrow_move_constructible<__node_allocator>::value)
    : base(allocator_type(_STD::move(__c.__node_alloc())))
{
    splice(end(), __c);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
list<_Tp, _Alloc>::list(list&& __c, const allocator_type& __a)
    : base(__a)
{
    if (__a == __c.get_allocator())
        splice(end(), __c);
    else
    {
        typedef move_iterator<iterator> _I;
        assign(_I(__c.begin()), _I(__c.end()));
    }
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
list<_Tp, _Alloc>&
list<_Tp, _Alloc>::operator=(list&& __c)
        _NOEXCEPT_(
            __node_alloc_traits::propagate_on_container_move_assignment::value &&
            is_nothrow_move_assignable<__node_allocator>::value)
{
    __move_assign(__c, integral_constant<bool,
          __node_alloc_traits::propagate_on_container_move_assignment::value>());
    return *this;
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::__move_assign(list& __c, false_type)
{
    if (base::__node_alloc() != __c.__node_alloc())
    {
        typedef move_iterator<iterator> _I;
        assign(_I(__c.begin()), _I(__c.end()));
    }
    else
        __move_assign(__c, true_type());
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::__move_assign(list& __c, true_type)
        _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value)
{
    clear();
    base::__move_assign_alloc(__c);
    splice(end(), __c);
}

#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES

template <class _Tp, class _Alloc>
template <class _InpIter>
void
list<_Tp, _Alloc>::assign(_InpIter __f, _InpIter __l,
                          typename enable_if<__is_input_iterator<_InpIter>::value>::type*)
{
    iterator __i = begin();
    iterator __e = end();
    for (; __f != __l && __i != __e; ++__f, ++__i)
        *__i = *__f;
    if (__i == __e)
        insert(__e, __f, __l);
    else
        erase(__i, __e);
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::assign(size_type __n, const value_type& __x)
{
    iterator __i = begin();
    iterator __e = end();
    for (; __n > 0 && __i != __e; --__n, ++__i)
        *__i = __x;
    if (__i == __e)
        insert(__e, __n, __x);
    else
        erase(__i, __e);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
_Alloc
list<_Tp, _Alloc>::get_allocator() const _NOEXCEPT
{
    return allocator_type(base::__node_alloc());
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::insert(const_iterator __p, const value_type& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __hold->__prev_ = 0;
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
    __link_nodes(const_cast<__node&>(*__p.__ptr_), *__hold, *__hold);
    ++base::__sz();
    return iterator(__hold.release());
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::insert(const_iterator __p, size_type __n, const value_type& __x)
{
    iterator __r(const_cast<__node_pointer>(__p.__ptr_));
    if (__n > 0)
    {
        size_type __ds = 0;
        __node_allocator& __na = base::__node_alloc();
        typedef __allocator_destructor<__node_allocator> _D;
        unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
        __hold->__prev_ = 0;
        __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
        ++__ds;
        __r = iterator(__hold.get());
        __hold.release();
        iterator __e = __r;
#ifndef _LIBCPP_NO_EXCEPTIONS
        try
        {
#endif  // _LIBCPP_NO_EXCEPTIONS
            for (--__n; __n != 0; --__n, ++__e, ++__ds)
            {
                __hold.reset(__node_alloc_traits::allocate(__na, 1));
                __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
                __e.__ptr_->__next_ = __hold.get();
                __hold->__prev_ = __e.__ptr_;
                __hold.release();
            }
#ifndef _LIBCPP_NO_EXCEPTIONS
        }
        catch (...)
        {
            while (true)
            {
                __node_alloc_traits::destroy(__na, _STD::addressof(*__e));
                __node_pointer __prev = __e.__ptr_->__prev_;
                __node_alloc_traits::deallocate(__na, __e.__ptr_, 1);
                if (__prev == 0)
                    break;
                __e = iterator(__prev);
            }
            throw;
        }
#endif  // _LIBCPP_NO_EXCEPTIONS
        __link_nodes(const_cast<__node&>(*__p.__ptr_), *__r.__ptr_, *__e.__ptr_);
        base::__sz() += __ds;
    }
    return __r;
}

template <class _Tp, class _Alloc>
template <class _InpIter>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::insert(const_iterator __p, _InpIter __f, _InpIter __l,
             typename enable_if<__is_input_iterator<_InpIter>::value>::type*)
{
    iterator __r(const_cast<__node_pointer>(__p.__ptr_));
    if (__f != __l)
    {
        size_type __ds = 0;
        __node_allocator& __na = base::__node_alloc();
        typedef __allocator_destructor<__node_allocator> _D;
        unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
        __hold->__prev_ = 0;
        __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), *__f);
        ++__ds;
        __r = iterator(__hold.get());
        __hold.release();
        iterator __e = __r;
#ifndef _LIBCPP_NO_EXCEPTIONS
        try
        {
#endif  // _LIBCPP_NO_EXCEPTIONS
            for (++__f; __f != __l; ++__f, ++__e, ++__ds)
            {
                __hold.reset(__node_alloc_traits::allocate(__na, 1));
                __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), *__f);
                __e.__ptr_->__next_ = __hold.get();
                __hold->__prev_ = __e.__ptr_;
                __hold.release();
            }
#ifndef _LIBCPP_NO_EXCEPTIONS
        }
        catch (...)
        {
            while (true)
            {
                __node_alloc_traits::destroy(__na, _STD::addressof(*__e));
                __node_pointer __prev = __e.__ptr_->__prev_;
                __node_alloc_traits::deallocate(__na, __e.__ptr_, 1);
                if (__prev == 0)
                    break;
                __e = iterator(__prev);
            }
            throw;
        }
#endif  // _LIBCPP_NO_EXCEPTIONS
        __link_nodes(const_cast<__node&>(*__p.__ptr_), *__r.__ptr_, *__e.__ptr_);
        base::__sz() += __ds;
    }
    return __r;
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::push_front(const value_type& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
    __link_nodes(*base::__end_.__next_, *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::push_back(const value_type& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
    __link_nodes(static_cast<__node&>(base::__end_), *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::push_front(value_type&& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::move(__x));
    __link_nodes(*base::__end_.__next_, *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::push_back(value_type&& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::move(__x));
    __link_nodes(static_cast<__node&>(base::__end_), *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

#ifndef _LIBCPP_HAS_NO_VARIADICS

template <class _Tp, class _Alloc>
template <class... _Args>
void
list<_Tp, _Alloc>::emplace_front(_Args&&... __args)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::forward<_Args>(__args)...);
    __link_nodes(*base::__end_.__next_, *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

template <class _Tp, class _Alloc>
template <class... _Args>
void
list<_Tp, _Alloc>::emplace_back(_Args&&... __args)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::forward<_Args>(__args)...);
    __link_nodes(static_cast<__node&>(base::__end_), *__hold, *__hold);
    ++base::__sz();
    __hold.release();
}

template <class _Tp, class _Alloc>
template <class... _Args>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::emplace(const_iterator __p, _Args&&... __args)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __hold->__prev_ = 0;
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::forward<_Args>(__args)...);
    __link_nodes(const_cast<__node&>(*__p.__ptr_), *__hold, *__hold);
    ++base::__sz();
    return iterator(__hold.release());
}

#endif  // _LIBCPP_HAS_NO_VARIADICS

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::insert(const_iterator __p, value_type&& __x)
{
    __node_allocator& __na = base::__node_alloc();
    typedef __allocator_destructor<__node_allocator> _D;
    unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
    __hold->__prev_ = 0;
    __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), _STD::move(__x));
    __link_nodes(const_cast<__node&>(*__p.__ptr_), *__hold, *__hold);
    ++base::__sz();
    return iterator(__hold.release());
}

#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::pop_front()
{
    __node_allocator& __na = base::__node_alloc();
    __node& __n = *base::__end_.__next_;
    base::__unlink_nodes(__n, __n);
    --base::__sz();
    __node_alloc_traits::destroy(__na, _STD::addressof(__n.__value_));
    __node_alloc_traits::deallocate(__na, _STD::addressof(__n), 1);
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::pop_back()
{
    __node_allocator& __na = base::__node_alloc();
    __node& __n = *base::__end_.__prev_;
    base::__unlink_nodes(__n, __n);
    --base::__sz();
    __node_alloc_traits::destroy(__na, _STD::addressof(__n.__value_));
    __node_alloc_traits::deallocate(__na, _STD::addressof(__n), 1);
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::erase(const_iterator __p)
{
    __node_allocator& __na = base::__node_alloc();
    __node& __n = const_cast<__node&>(*__p.__ptr_);
    __node_pointer __r = __n.__next_;
    base::__unlink_nodes(__n, __n);
    --base::__sz();
    __node_alloc_traits::destroy(__na, _STD::addressof(__n.__value_));
    __node_alloc_traits::deallocate(__na, _STD::addressof(__n), 1);
    return iterator(__r);
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::erase(const_iterator __f, const_iterator __l)
{
    if (__f != __l)
    {
        __node_allocator& __na = base::__node_alloc();
        base::__unlink_nodes(const_cast<__node&>(*__f.__ptr_), *__l.__ptr_->__prev_);
        while (__f != __l)
        {
            __node& __n = const_cast<__node&>(*__f.__ptr_);
            ++__f;
            --base::__sz();
            __node_alloc_traits::destroy(__na, _STD::addressof(__n.__value_));
            __node_alloc_traits::deallocate(__na, _STD::addressof(__n), 1);
        }
    }
    return iterator(const_cast<__node_pointer>(__l.__ptr_));
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::resize(size_type __n)
{
    if (__n < base::__sz())
        erase(__iterator(__n), end());
    else if (__n > base::__sz())
    {
        __n -= base::__sz();
        size_type __ds = 0;
        __node_allocator& __na = base::__node_alloc();
        typedef __allocator_destructor<__node_allocator> _D;
        unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
        __hold->__prev_ = 0;
        __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_));
        ++__ds;
        iterator __r = iterator(__hold.release());
        iterator __e = __r;
#ifndef _LIBCPP_NO_EXCEPTIONS
        try
        {
#endif  // _LIBCPP_NO_EXCEPTIONS
            for (--__n; __n != 0; --__n, ++__e, ++__ds)
            {
                __hold.reset(__node_alloc_traits::allocate(__na, 1));
                __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_));
                __e.__ptr_->__next_ = __hold.get();
                __hold->__prev_ = __e.__ptr_;
                __hold.release();
            }
#ifndef _LIBCPP_NO_EXCEPTIONS
        }
        catch (...)
        {
            while (true)
            {
                __node_alloc_traits::destroy(__na, _STD::addressof(*__e));
                __node_pointer __prev = __e.__ptr_->__prev_;
                __node_alloc_traits::deallocate(__na, __e.__ptr_, 1);
                if (__prev == 0)
                    break;
                __e = iterator(__prev);
            }
            throw;
        }
#endif  // _LIBCPP_NO_EXCEPTIONS
        __link_nodes(static_cast<__node&>(base::__end_), *__r.__ptr_, *__e.__ptr_);
        base::__sz() += __ds;
    }
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::resize(size_type __n, const value_type& __x)
{
    if (__n < base::__sz())
        erase(__iterator(__n), end());
    else if (__n > base::__sz())
    {
        __n -= base::__sz();
        size_type __ds = 0;
        __node_allocator& __na = base::__node_alloc();
        typedef __allocator_destructor<__node_allocator> _D;
        unique_ptr<__node, _D> __hold(__node_alloc_traits::allocate(__na, 1), _D(__na, 1));
        __hold->__prev_ = 0;
        __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
        ++__ds;
        iterator __r = iterator(__hold.release());
        iterator __e = __r;
#ifndef _LIBCPP_NO_EXCEPTIONS
        try
        {
#endif  // _LIBCPP_NO_EXCEPTIONS
            for (--__n; __n != 0; --__n, ++__e, ++__ds)
            {
                __hold.reset(__node_alloc_traits::allocate(__na, 1));
                __node_alloc_traits::construct(__na, _STD::addressof(__hold->__value_), __x);
                __e.__ptr_->__next_ = __hold.get();
                __hold->__prev_ = __e.__ptr_;
                __hold.release();
            }
#ifndef _LIBCPP_NO_EXCEPTIONS
        }
        catch (...)
        {
            while (true)
            {
                __node_alloc_traits::destroy(__na, _STD::addressof(*__e));
                __node_pointer __prev = __e.__ptr_->__prev_;
                __node_alloc_traits::deallocate(__na, __e.__ptr_, 1);
                if (__prev == 0)
                    break;
                __e = iterator(__prev);
            }
            throw;
        }
#endif  // _LIBCPP_NO_EXCEPTIONS
        __link_nodes(static_cast<__node&>(base::__end_), *__r.__ptr_, *__e.__ptr_);
        base::__sz() += __ds;
    }
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::splice(const_iterator __p, list& __c)
{
    if (!__c.empty())
    {
        __node& __f = *__c.__end_.__next_;
        __node& __l = *__c.__end_.__prev_;
        base::__unlink_nodes(__f, __l);
        __link_nodes(const_cast<__node&>(*__p.__ptr_), __f, __l);
        base::__sz() += __c.__sz();
        __c.__sz() = 0;
    }
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::splice(const_iterator __p, list& __c, const_iterator __i)
{
    if (__p != __i && __p != _STD::next(__i))
    {
        __node& __f = const_cast<__node&>(*__i.__ptr_);
        base::__unlink_nodes(__f, __f);
        __link_nodes(const_cast<__node&>(*__p.__ptr_), __f, __f);
        --__c.__sz();
        ++base::__sz();
    }
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::splice(const_iterator __p, list& __c, const_iterator __f, const_iterator __l)
{
    if (__f != __l)
    {
        if (this != &__c)
        {
            size_type __s = _STD::distance(__f, __l);
            __c.__sz() -= __s;
            base::__sz() += __s;
        }
        __node& __first = const_cast<__node&>(*__f.__ptr_);
        --__l;
        __node& __last = const_cast<__node&>(*__l.__ptr_);
        base::__unlink_nodes(__first, __last);
        __link_nodes(const_cast<__node&>(*__p.__ptr_), __first, __last);
    }
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::remove(const value_type& __x)
{
    for (iterator __i = begin(), __e = end(); __i != __e;)
    {
        if (*__i == __x)
        {
            iterator __j = _STD::next(__i);
            for (; __j != __e && *__j == __x; ++__j)
                ;
            __i = erase(__i, __j);
        }
        else
            ++__i;
    }
}

template <class _Tp, class _Alloc>
template <class _Pred>
void
list<_Tp, _Alloc>::remove_if(_Pred __pred)
{
    for (iterator __i = begin(), __e = end(); __i != __e;)
    {
        if (__pred(*__i))
        {
            iterator __j = _STD::next(__i);
            for (; __j != __e && __pred(*__j); ++__j)
                ;
            __i = erase(__i, __j);
        }
        else
            ++__i;
    }
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
list<_Tp, _Alloc>::unique()
{
    unique(__equal_to<value_type>());
}

template <class _Tp, class _Alloc>
template <class _BinaryPred>
void
list<_Tp, _Alloc>::unique(_BinaryPred __binary_pred)
{
    for (iterator __i = begin(), __e = end(); __i != __e;)
    {
        iterator __j = _STD::next(__i);
        for (; __j != __e && __binary_pred(*__i, *__j); ++__j)
            ;
        if (++__i != __j)
            __i = erase(__i, __j);
    }
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
list<_Tp, _Alloc>::merge(list& __c)
{
    merge(__c, __less<value_type>());
}

template <class _Tp, class _Alloc>
template <class _Comp>
void
list<_Tp, _Alloc>::merge(list& __c, _Comp __comp)
{
    if (this != &__c)
    {
        iterator __f1 = begin();
        iterator __e1 = end();
        iterator __f2 = __c.begin();
        iterator __e2 = __c.end();
        while (__f1 != __e1 && __f2 != __e2)
        {
            if (__comp(*__f2, *__f1))
            {
                size_type __ds = 1;
                iterator __m2 = _STD::next(__f2);
                for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2, ++__ds)
                    ;
                base::__sz() += __ds;
                __c.__sz() -= __ds;
                __node& __f = *__f2.__ptr_;
                __node& __l = *__m2.__ptr_->__prev_;
                __f2 = __m2;
                base::__unlink_nodes(__f, __l);
                __m2 = _STD::next(__f1);
                __link_nodes(*__f1.__ptr_, __f, __l);
                __f1 = __m2;
            }
            else
                ++__f1;
        }
        splice(__e1, __c);
    }
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
list<_Tp, _Alloc>::sort()
{
    sort(__less<value_type>());
}

template <class _Tp, class _Alloc>
template <class _Comp>
inline _LIBCPP_INLINE_VISIBILITY
void
list<_Tp, _Alloc>::sort(_Comp __comp)
{
    __sort(begin(), end(), base::__sz(), __comp);
}

template <class _Tp, class _Alloc>
template <class _Comp>
typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::__sort(iterator __f1, iterator __e2, size_type __n, _Comp& __comp)
{
    switch (__n)
    {
    case 0:
    case 1:
        return __f1;
    case 2:
        if (__comp(*--__e2, *__f1))
        {
            __node& __f = *__e2.__ptr_;
            base::__unlink_nodes(__f, __f);
            __link_nodes(*__f1.__ptr_, __f, __f);
            return __e2;
        }
        return __f1;
    }
    size_type __n2 = __n / 2;
    iterator __e1 = _STD::next(__f1, __n2);
    iterator  __r = __f1 = __sort(__f1, __e1, __n2, __comp);
    iterator __f2 = __e1 = __sort(__e1, __e2, __n - __n2, __comp);
    if (__comp(*__f2, *__f1))
    {
        iterator __m2 = _STD::next(__f2);
        for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2)
            ;
        __node& __f = *__f2.__ptr_;
        __node& __l = *__m2.__ptr_->__prev_;
        __r = __f2;
        __e1 = __f2 = __m2;
        base::__unlink_nodes(__f, __l);
        __m2 = _STD::next(__f1);
        __link_nodes(*__f1.__ptr_, __f, __l);
        __f1 = __m2;
    }
    else
        ++__f1;
    while (__f1 != __e1 && __f2 != __e2)
    {
        if (__comp(*__f2, *__f1))
        {
            iterator __m2 = _STD::next(__f2);
            for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2)
                ;
            __node& __f = *__f2.__ptr_;
            __node& __l = *__m2.__ptr_->__prev_;
            if (__e1 == __f2)
                __e1 = __m2;
            __f2 = __m2;
            base::__unlink_nodes(__f, __l);
            __m2 = _STD::next(__f1);
            __link_nodes(*__f1.__ptr_, __f, __l);
            __f1 = __m2;
        }
        else
            ++__f1;
    }
    return __r;
}

template <class _Tp, class _Alloc>
void
list<_Tp, _Alloc>::reverse() _NOEXCEPT
{
    if (base::__sz() > 1)
    {
        iterator __e = end();
        for (iterator __i = begin(); __i != __e; --__i)
            _STD::swap(__i.__ptr_->__prev_, __i.__ptr_->__next_);
        _STD::swap(__e.__ptr_->__prev_, __e.__ptr_->__next_);
    }
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return __x.size() == __y.size() && _STD::equal(__x.begin(), __x.end(), __y.begin());
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator< (const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return _STD::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return !(__x == __y);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator> (const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return __y < __x;
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator>=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return !(__x < __y);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator<=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
{
    return !(__y < __x);
}

template <class _Tp, class _Alloc>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(list<_Tp, _Alloc>& __x, list<_Tp, _Alloc>& __y)
    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
{
    __x.swap(__y);
}

_LIBCPP_END_NAMESPACE_STD

#endif  // _LIBCPP_LIST