// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___CXX03_LIST
#define _LIBCPP___CXX03_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);
    explicit list(size_type n, const allocator_type& a); // C++14
    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);
    template<container-compatible-range<T> R>
      list(from_range_t, R&& rg, const Allocator& = Allocator()); // C++23
    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);
    template<container-compatible-range<T> R>
      void assign_range(R&& rg); // C++23
    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>
        reference emplace_front(Args&&... args); // reference in C++17
    void pop_front();
    template <class... Args>
        reference emplace_back(Args&&... args);  // reference in C++17
    void pop_back();
    void push_front(const value_type& x);
    void push_front(value_type&& x);
    template<container-compatible-range<T> R>
      void prepend_range(R&& rg); // C++23
    void push_back(const value_type& x);
    void push_back(value_type&& x);
    template<container-compatible-range<T> R>
      void append_range(R&& rg); // C++23
    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);
    template<container-compatible-range<T> R>
      iterator insert_range(const_iterator position, R&& rg); // C++23
    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_traits<allocator_type>::is_always_equal::value);  // C++17
    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);

    size_type remove(const value_type& value);       // void before C++20
    template <class Pred>
      size_type remove_if(Pred pred);                // void before C++20
    size_type unique();                              // void before C++20
    template <class BinaryPredicate>
      size_type unique(BinaryPredicate binary_pred); // void before C++20
    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 InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
    list(InputIterator, InputIterator, Allocator = Allocator())
    -> list<typename iterator_traits<InputIterator>::value_type, Allocator>;  // C++17

template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
  list(from_range_t, R&&, Allocator = Allocator())
    -> list<ranges::range_value_t<R>, Allocator>; // C++23

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);     // removed in C++20
template <class T, class Alloc>
    bool operator!=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
template <class T, class Alloc>
    bool operator> (const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
template <class T, class Alloc>
    bool operator>=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
template <class T, class Alloc>
    bool operator<=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
template<class T, class Allocator>
  synth-three-way-result<T> operator<=>(const list<T, Allocator>& x,
                                        const list<T, Allocator>& y);    // since C++20

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

template <class T, class Allocator, class U>
    typename list<T, Allocator>::size_type
    erase(list<T, Allocator>& c, const U& value);       // since C++20
template <class T, class Allocator, class Predicate>
    typename list<T, Allocator>::size_type
    erase_if(list<T, Allocator>& c, Predicate pred);    // since C++20

}  // std

*/

#include <__cxx03/__algorithm/comp.h>
#include <__cxx03/__algorithm/equal.h>
#include <__cxx03/__algorithm/lexicographical_compare.h>
#include <__cxx03/__algorithm/min.h>
#include <__cxx03/__assert>
#include <__cxx03/__config>
#include <__cxx03/__iterator/distance.h>
#include <__cxx03/__iterator/iterator_traits.h>
#include <__cxx03/__iterator/move_iterator.h>
#include <__cxx03/__iterator/next.h>
#include <__cxx03/__iterator/prev.h>
#include <__cxx03/__iterator/reverse_iterator.h>
#include <__cxx03/__memory/addressof.h>
#include <__cxx03/__memory/allocation_guard.h>
#include <__cxx03/__memory/allocator.h>
#include <__cxx03/__memory/allocator_traits.h>
#include <__cxx03/__memory/compressed_pair.h>
#include <__cxx03/__memory/construct_at.h>
#include <__cxx03/__memory/pointer_traits.h>
#include <__cxx03/__memory/swap_allocator.h>
#include <__cxx03/__type_traits/conditional.h>
#include <__cxx03/__type_traits/is_allocator.h>
#include <__cxx03/__type_traits/is_nothrow_assignable.h>
#include <__cxx03/__type_traits/is_nothrow_constructible.h>
#include <__cxx03/__type_traits/is_pointer.h>
#include <__cxx03/__type_traits/is_same.h>
#include <__cxx03/__type_traits/type_identity.h>
#include <__cxx03/__utility/forward.h>
#include <__cxx03/__utility/move.h>
#include <__cxx03/__utility/swap.h>
#include <__cxx03/cstring>
#include <__cxx03/limits>
#include <__cxx03/new> // __launder
#include <__cxx03/version>

// standard-mandated includes

// [iterator.range]
#include <__cxx03/__iterator/access.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__cxx03/__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp, class _VoidPtr>
struct __list_node;
template <class _Tp, class _VoidPtr>
struct __list_node_base;

template <class _Tp, class _VoidPtr>
struct __list_node_pointer_traits {
  typedef __rebind_pointer_t<_VoidPtr, __list_node<_Tp, _VoidPtr> > __node_pointer;
  typedef __rebind_pointer_t<_VoidPtr, __list_node_base<_Tp, _VoidPtr> > __base_pointer;

#if defined(_LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB)
  typedef __base_pointer __link_pointer;
#else
  typedef __conditional_t<is_pointer<_VoidPtr>::value, __base_pointer, __node_pointer> __link_pointer;
#endif

  typedef __conditional_t<is_same<__link_pointer, __node_pointer>::value, __base_pointer, __node_pointer>
      __non_link_pointer;

  static _LIBCPP_HIDE_FROM_ABI __link_pointer __unsafe_link_pointer_cast(__link_pointer __p) { return __p; }

  static _LIBCPP_HIDE_FROM_ABI __link_pointer __unsafe_link_pointer_cast(__non_link_pointer __p) {
    return static_cast<__link_pointer>(static_cast<_VoidPtr>(__p));
  }
};

template <class _Tp, class _VoidPtr>
struct __list_node_base {
  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
  typedef typename _NodeTraits::__node_pointer __node_pointer;
  typedef typename _NodeTraits::__base_pointer __base_pointer;
  typedef typename _NodeTraits::__link_pointer __link_pointer;

  __link_pointer __prev_;
  __link_pointer __next_;

  _LIBCPP_HIDE_FROM_ABI __list_node_base()
      : __prev_(_NodeTraits::__unsafe_link_pointer_cast(__self())),
        __next_(_NodeTraits::__unsafe_link_pointer_cast(__self())) {}

  _LIBCPP_HIDE_FROM_ABI explicit __list_node_base(__link_pointer __prev, __link_pointer __next)
      : __prev_(__prev), __next_(__next) {}

  _LIBCPP_HIDE_FROM_ABI __base_pointer __self() { return pointer_traits<__base_pointer>::pointer_to(*this); }

  _LIBCPP_HIDE_FROM_ABI __node_pointer __as_node() { return static_cast<__node_pointer>(__self()); }
};

template <class _Tp, class _VoidPtr>
struct __list_node : public __list_node_base<_Tp, _VoidPtr> {
  // We allow starting the lifetime of nodes without initializing the value held by the node,
  // since that is handled by the list itself in order to be allocator-aware.

private:
  _ALIGNAS_TYPE(_Tp) char __buffer_[sizeof(_Tp)];

public:
  _LIBCPP_HIDE_FROM_ABI _Tp& __get_value() { return *std::__launder(reinterpret_cast<_Tp*>(&__buffer_)); }

  typedef __list_node_base<_Tp, _VoidPtr> __base;
  typedef typename __base::__link_pointer __link_pointer;

  _LIBCPP_HIDE_FROM_ABI explicit __list_node(__link_pointer __prev, __link_pointer __next) : __base(__prev, __next) {}
  _LIBCPP_HIDE_FROM_ABI ~__list_node() {}

  _LIBCPP_HIDE_FROM_ABI __link_pointer __as_link() { return static_cast<__link_pointer>(__base::__self()); }
};

template <class _Tp, class _Alloc = allocator<_Tp> >
class _LIBCPP_TEMPLATE_VIS list;
template <class _Tp, class _Alloc>
class __list_imp;
template <class _Tp, class _VoidPtr>
class _LIBCPP_TEMPLATE_VIS __list_const_iterator;

template <class _Tp, class _VoidPtr>
class _LIBCPP_TEMPLATE_VIS __list_iterator {
  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
  typedef typename _NodeTraits::__link_pointer __link_pointer;

  __link_pointer __ptr_;

  _LIBCPP_HIDE_FROM_ABI explicit __list_iterator(__link_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 __rebind_pointer_t<_VoidPtr, value_type> pointer;
  typedef typename pointer_traits<pointer>::difference_type difference_type;

  _LIBCPP_HIDE_FROM_ABI __list_iterator() _NOEXCEPT : __ptr_(nullptr) {}

  _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __ptr_->__as_node()->__get_value(); }
  _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
    return pointer_traits<pointer>::pointer_to(__ptr_->__as_node()->__get_value());
  }

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

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

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

template <class _Tp, class _VoidPtr>
class _LIBCPP_TEMPLATE_VIS __list_const_iterator {
  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
  typedef typename _NodeTraits::__link_pointer __link_pointer;

  __link_pointer __ptr_;

  _LIBCPP_HIDE_FROM_ABI explicit __list_const_iterator(__link_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 __rebind_pointer_t<_VoidPtr, const value_type> pointer;
  typedef typename pointer_traits<pointer>::difference_type difference_type;

  _LIBCPP_HIDE_FROM_ABI __list_const_iterator() _NOEXCEPT : __ptr_(nullptr) {}
  _LIBCPP_HIDE_FROM_ABI __list_const_iterator(const __list_iterator<_Tp, _VoidPtr>& __p) _NOEXCEPT
      : __ptr_(__p.__ptr_) {}

  _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __ptr_->__as_node()->__get_value(); }
  _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
    return pointer_traits<pointer>::pointer_to(__ptr_->__as_node()->__get_value());
  }

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

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

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

template <class _Tp, class _Alloc>
class __list_imp {
public:
  __list_imp(const __list_imp&)            = delete;
  __list_imp& operator=(const __list_imp&) = delete;

  typedef _Alloc allocator_type;
  typedef allocator_traits<allocator_type> __alloc_traits;
  typedef typename __alloc_traits::size_type size_type;

protected:
  typedef _Tp value_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_type;
  typedef __rebind_alloc<__alloc_traits, __node_type> __node_allocator;
  typedef allocator_traits<__node_allocator> __node_alloc_traits;
  typedef typename __node_alloc_traits::pointer __node_pointer;
  typedef typename __node_alloc_traits::pointer __node_const_pointer;
  typedef __list_node_pointer_traits<value_type, __void_pointer> __node_pointer_traits;
  typedef typename __node_pointer_traits::__link_pointer __link_pointer;
  typedef __link_pointer __link_const_pointer;
  typedef typename __alloc_traits::pointer pointer;
  typedef typename __alloc_traits::const_pointer const_pointer;
  typedef typename __alloc_traits::difference_type difference_type;

  typedef __rebind_alloc<__alloc_traits, __node_base> __node_base_allocator;
  typedef typename allocator_traits<__node_base_allocator>::pointer __node_base_pointer;
  static_assert(!is_same<allocator_type, __node_allocator>::value,
                "internal allocator type must differ from user-specified type; otherwise overload resolution breaks");

  __node_base __end_;
  __compressed_pair<size_type, __node_allocator> __size_alloc_;

  _LIBCPP_HIDE_FROM_ABI __link_pointer __end_as_link() const _NOEXCEPT {
    return __node_pointer_traits::__unsafe_link_pointer_cast(const_cast<__node_base&>(__end_).__self());
  }

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

  _LIBCPP_HIDE_FROM_ABI size_type __node_alloc_max_size() const _NOEXCEPT {
    return __node_alloc_traits::max_size(__node_alloc());
  }
  _LIBCPP_HIDE_FROM_ABI static void __unlink_nodes(__link_pointer __f, __link_pointer __l) _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI __list_imp();
  _LIBCPP_HIDE_FROM_ABI __list_imp(const allocator_type& __a);
  _LIBCPP_HIDE_FROM_ABI __list_imp(const __node_allocator& __a);
  _LIBCPP_HIDE_FROM_ABI ~__list_imp();
  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __sz() == 0; }

  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return iterator(__end_.__next_); }
  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return const_iterator(__end_.__next_); }
  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return iterator(__end_as_link()); }
  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return const_iterator(__end_as_link()); }

  _LIBCPP_HIDE_FROM_ABI void swap(__list_imp& __c);

  _LIBCPP_HIDE_FROM_ABI 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_HIDE_FROM_ABI void __move_assign_alloc(__list_imp& __c) {
    __move_assign_alloc(
        __c, integral_constant<bool, __node_alloc_traits::propagate_on_container_move_assignment::value>());
  }

  template <class... _Args>
  _LIBCPP_HIDE_FROM_ABI __node_pointer __create_node(__link_pointer __prev, __link_pointer __next, _Args&&... __args) {
    __node_allocator& __alloc = __node_alloc();
    __allocation_guard<__node_allocator> __guard(__alloc, 1);
    // Begin the lifetime of the node itself. Note that this doesn't begin the lifetime of the value
    // held inside the node, since we need to use the allocator's construct() method for that.
    //
    // We don't use the allocator's construct() method to construct the node itself since the
    // Cpp17FooInsertable named requirements don't require the allocator's construct() method
    // to work on anything other than the value_type.
    std::__construct_at(std::addressof(*__guard.__get()), __prev, __next);

    // Now construct the value_type using the allocator's construct() method.
    __node_alloc_traits::construct(
        __alloc, std::addressof(__guard.__get()->__get_value()), std::forward<_Args>(__args)...);
    return __guard.__release_ptr();
  }

  _LIBCPP_HIDE_FROM_ABI void __delete_node(__node_pointer __node) {
    // For the same reason as above, we use the allocator's destroy() method for the value_type,
    // but not for the node itself.
    __node_allocator& __alloc = __node_alloc();
    __node_alloc_traits::destroy(__alloc, std::addressof(__node->__get_value()));
    std::__destroy_at(std::addressof(*__node));
    __node_alloc_traits::deallocate(__alloc, __node, 1);
  }

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

  _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __list_imp&, false_type) {}

  _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__list_imp& __c, true_type) {
    __node_alloc() = std::move(__c.__node_alloc());
  }

  _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__list_imp&, false_type) _NOEXCEPT {}
};

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

template <class _Tp, class _Alloc>
inline __list_imp<_Tp, _Alloc>::__list_imp() : __size_alloc_(0, __default_init_tag()) {}

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

template <class _Tp, class _Alloc>
inline __list_imp<_Tp, _Alloc>::__list_imp(const __node_allocator& __a) : __size_alloc_(0, __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()) {
    __link_pointer __f = __end_.__next_;
    __link_pointer __l = __end_as_link();
    __unlink_nodes(__f, __l->__prev_);
    __sz() = 0;
    while (__f != __l) {
      __node_pointer __np = __f->__as_node();
      __f                 = __f->__next_;
      __delete_node(__np);
    }
  }
}

template <class _Tp, class _Alloc>
void __list_imp<_Tp, _Alloc>::swap(__list_imp& __c) {
  _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
      __alloc_traits::propagate_on_container_swap::value || this->__node_alloc() == __c.__node_alloc(),
      "list::swap: Either propagate_on_container_swap must be true"
      " or the allocators must compare equal");
  using std::swap;
  std::__swap_allocator(__node_alloc(), __c.__node_alloc());
  swap(__sz(), __c.__sz());
  swap(__end_, __c.__end_);
  if (__sz() == 0)
    __end_.__next_ = __end_.__prev_ = __end_as_link();
  else
    __end_.__prev_->__next_ = __end_.__next_->__prev_ = __end_as_link();
  if (__c.__sz() == 0)
    __c.__end_.__next_ = __c.__end_.__prev_ = __c.__end_as_link();
  else
    __c.__end_.__prev_->__next_ = __c.__end_.__next_->__prev_ = __c.__end_as_link();
}

template <class _Tp, class _Alloc /*= allocator<_Tp>*/>
class _LIBCPP_TEMPLATE_VIS list : private __list_imp<_Tp, _Alloc> {
  typedef __list_imp<_Tp, _Alloc> __base;
  typedef typename __base::__node_type __node_type;
  typedef typename __base::__node_allocator __node_allocator;
  typedef typename __base::__node_pointer __node_pointer;
  typedef typename __base::__node_alloc_traits __node_alloc_traits;
  typedef typename __base::__node_base __node_base;
  typedef typename __base::__node_base_pointer __node_base_pointer;
  typedef typename __base::__link_pointer __link_pointer;

public:
  typedef _Tp value_type;
  typedef _Alloc allocator_type;
  static_assert(__check_valid_allocator<allocator_type>::value);
  static_assert(is_same<value_type, typename allocator_type::value_type>::value,
                "Allocator::value_type must be same type as 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;
  typedef void __remove_return_type;

  _LIBCPP_HIDE_FROM_ABI list() {}
  _LIBCPP_HIDE_FROM_ABI explicit list(const allocator_type& __a) : __base(__a) {}
  _LIBCPP_HIDE_FROM_ABI explicit list(size_type __n);
  _LIBCPP_HIDE_FROM_ABI list(size_type __n, const value_type& __x);
  template <__enable_if_t<__is_allocator<_Alloc>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI list(size_type __n, const value_type& __x, const allocator_type& __a) : __base(__a) {
    for (; __n > 0; --__n)
      push_back(__x);
  }

  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI list(_InpIter __f, _InpIter __l);

  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI list(_InpIter __f, _InpIter __l, const allocator_type& __a);

  _LIBCPP_HIDE_FROM_ABI list(const list& __c);
  _LIBCPP_HIDE_FROM_ABI list(const list& __c, const __type_identity_t<allocator_type>& __a);
  _LIBCPP_HIDE_FROM_ABI list& operator=(const list& __c);

  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI void assign(_InpIter __f, _InpIter __l);

  _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __x);

  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __base::__sz(); }
  _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __base::empty(); }
  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
    return std::min<size_type>(__base::__node_alloc_max_size(), numeric_limits<difference_type >::max());
  }

  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return __base::begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return __base::begin(); }
  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return __base::end(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return __base::end(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return __base::begin(); }
  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return __base::end(); }

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

  _LIBCPP_HIDE_FROM_ABI reference front() {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
    return __base::__end_.__next_->__as_node()->__get_value();
  }
  _LIBCPP_HIDE_FROM_ABI const_reference front() const {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
    return __base::__end_.__next_->__as_node()->__get_value();
  }
  _LIBCPP_HIDE_FROM_ABI reference back() {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
    return __base::__end_.__prev_->__as_node()->__get_value();
  }
  _LIBCPP_HIDE_FROM_ABI const_reference back() const {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
    return __base::__end_.__prev_->__as_node()->__get_value();
  }

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

  _LIBCPP_HIDE_FROM_ABI void __emplace_back(value_type const& __arg) { push_back(__arg); }

  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __x);
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, size_type __n, const value_type& __x);

  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _InpIter __f, _InpIter __l);

  _LIBCPP_HIDE_FROM_ABI void swap(list& __c) { __base::swap(__c); }
  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { __base::clear(); }

  _LIBCPP_HIDE_FROM_ABI void pop_front();
  _LIBCPP_HIDE_FROM_ABI void pop_back();

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

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

  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c);
  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c, const_iterator __i);
  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c, const_iterator __f, const_iterator __l);

  _LIBCPP_HIDE_FROM_ABI __remove_return_type remove(const value_type& __x);
  template <class _Pred>
  _LIBCPP_HIDE_FROM_ABI __remove_return_type remove_if(_Pred __pred);
  _LIBCPP_HIDE_FROM_ABI __remove_return_type unique() { return unique(__equal_to()); }
  template <class _BinaryPred>
  _LIBCPP_HIDE_FROM_ABI __remove_return_type unique(_BinaryPred __binary_pred);
  _LIBCPP_HIDE_FROM_ABI void merge(list& __c);
  template <class _Comp>
  _LIBCPP_HIDE_FROM_ABI void merge(list& __c, _Comp __comp);

  _LIBCPP_HIDE_FROM_ABI void sort();
  template <class _Comp>
  _LIBCPP_HIDE_FROM_ABI void sort(_Comp __comp);

  _LIBCPP_HIDE_FROM_ABI void reverse() _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI bool __invariants() const;

private:
  template <class _Iterator, class _Sentinel>
  _LIBCPP_HIDE_FROM_ABI void __assign_with_sentinel(_Iterator __f, _Sentinel __l);

  template <class _Iterator, class _Sentinel>
  _LIBCPP_HIDE_FROM_ABI iterator __insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l);

  _LIBCPP_HIDE_FROM_ABI static void __link_nodes(__link_pointer __p, __link_pointer __f, __link_pointer __l);
  _LIBCPP_HIDE_FROM_ABI void __link_nodes_at_front(__link_pointer __f, __link_pointer __l);
  _LIBCPP_HIDE_FROM_ABI void __link_nodes_at_back(__link_pointer __f, __link_pointer __l);
  _LIBCPP_HIDE_FROM_ABI iterator __iterator(size_type __n);
  // TODO: Make this _LIBCPP_HIDE_FROM_ABI
  template <class _Comp>
  _LIBCPP_HIDDEN static iterator __sort(iterator __f1, iterator __e2, size_type __n, _Comp& __comp);

  _LIBCPP_HIDE_FROM_ABI void __move_assign(list& __c, true_type);
  _LIBCPP_HIDE_FROM_ABI void __move_assign(list& __c, false_type);
};

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

// Link in nodes [__f, __l] at the front of the list
template <class _Tp, class _Alloc>
inline void list<_Tp, _Alloc>::__link_nodes_at_front(__link_pointer __f, __link_pointer __l) {
  __f->__prev_           = __base::__end_as_link();
  __l->__next_           = __base::__end_.__next_;
  __l->__next_->__prev_  = __l;
  __base::__end_.__next_ = __f;
}

// Link in nodes [__f, __l] at the back of the list
template <class _Tp, class _Alloc>
inline void list<_Tp, _Alloc>::__link_nodes_at_back(__link_pointer __f, __link_pointer __l) {
  __l->__next_           = __base::__end_as_link();
  __f->__prev_           = __base::__end_.__prev_;
  __f->__prev_->__next_  = __f;
  __base::__end_.__prev_ = __l;
}

template <class _Tp, class _Alloc>
inline 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)
    push_back(value_type());
}

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>
template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l) {
  for (; __f != __l; ++__f)
    __emplace_back(*__f);
}

template <class _Tp, class _Alloc>
template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l, const allocator_type& __a) : __base(__a) {
  for (; __f != __l; ++__f)
    __emplace_back(*__f);
}

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

template <class _Tp, class _Alloc>
template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
void list<_Tp, _Alloc>::assign(_InpIter __f, _InpIter __l) {
  __assign_with_sentinel(__f, __l);
}

template <class _Tp, class _Alloc>
template <class _Iterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI void list<_Tp, _Alloc>::__assign_with_sentinel(_Iterator __f, _Sentinel __l) {
  iterator __i = begin();
  iterator __e = end();
  for (; __f != __l && __i != __e; ++__f, (void)++__i)
    *__i = *__f;
  if (__i == __e)
    __insert_with_sentinel(__e, std::move(__f), std::move(__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, (void)++__i)
    *__i = __x;
  if (__i == __e)
    insert(__e, __n, __x);
  else
    erase(__i, __e);
}

template <class _Tp, class _Alloc>
inline _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_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
  __link_nodes(__p.__ptr_, __node->__as_link(), __node->__as_link());
  ++__base::__sz();
  return iterator(__node->__as_link());
}

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(__p.__ptr_);
  if (__n > 0) {
    size_type __ds        = 0;
    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
    ++__ds;
    __r          = iterator(__node->__as_link());
    iterator __e = __r;
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, __x)->__as_link();
      }
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    } catch (...) {
      while (true) {
        __link_pointer __prev    = __e.__ptr_->__prev_;
        __node_pointer __current = __e.__ptr_->__as_node();
        this->__delete_node(__current);
        if (__prev == 0)
          break;
        __e = iterator(__prev);
      }
      throw;
    }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    __link_nodes(__p.__ptr_, __r.__ptr_, __e.__ptr_);
    __base::__sz() += __ds;
  }
  return __r;
}

template <class _Tp, class _Alloc>
template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::insert(const_iterator __p, _InpIter __f, _InpIter __l) {
  return __insert_with_sentinel(__p, __f, __l);
}

template <class _Tp, class _Alloc>
template <class _Iterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI typename list<_Tp, _Alloc>::iterator
list<_Tp, _Alloc>::__insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l) {
  iterator __r(__p.__ptr_);
  if (__f != __l) {
    size_type __ds        = 0;
    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, *__f);
    ++__ds;
    __r          = iterator(__node->__as_link());
    iterator __e = __r;
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
      for (++__f; __f != __l; ++__f, (void)++__e, ++__ds) {
        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, *__f)->__as_link();
      }
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    } catch (...) {
      while (true) {
        __link_pointer __prev    = __e.__ptr_->__prev_;
        __node_pointer __current = __e.__ptr_->__as_node();
        this->__delete_node(__current);
        if (__prev == 0)
          break;
        __e = iterator(__prev);
      }
      throw;
    }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    __link_nodes(__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_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
  __link_pointer __nl   = __node->__as_link();
  __link_nodes_at_front(__nl, __nl);
  ++__base::__sz();
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::push_back(const value_type& __x) {
  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
  __link_pointer __nl   = __node->__as_link();
  __link_nodes_at_back(__nl, __nl);
  ++__base::__sz();
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::pop_front() {
  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::pop_front() called with empty list");
  __link_pointer __n = __base::__end_.__next_;
  __base::__unlink_nodes(__n, __n);
  --__base::__sz();
  this->__delete_node(__n->__as_node());
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::pop_back() {
  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::pop_back() called on an empty list");
  __link_pointer __n = __base::__end_.__prev_;
  __base::__unlink_nodes(__n, __n);
  --__base::__sz();
  this->__delete_node(__n->__as_node());
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::erase(const_iterator __p) {
  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p != end(), "list::erase(iterator) called with a non-dereferenceable iterator");
  __link_pointer __n = __p.__ptr_;
  __link_pointer __r = __n->__next_;
  __base::__unlink_nodes(__n, __n);
  --__base::__sz();
  this->__delete_node(__n->__as_node());
  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) {
    __base::__unlink_nodes(__f.__ptr_, __l.__ptr_->__prev_);
    while (__f != __l) {
      __link_pointer __n = __f.__ptr_;
      ++__f;
      --__base::__sz();
      this->__delete_node(__n->__as_node());
    }
  }
  return iterator(__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_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr);
    ++__ds;
    iterator __r = iterator(__node->__as_link());
    iterator __e = __r;
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr)->__as_link();
      }
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    } catch (...) {
      while (true) {
        __link_pointer __prev    = __e.__ptr_->__prev_;
        __node_pointer __current = __e.__ptr_->__as_node();
        this->__delete_node(__current);
        if (__prev == 0)
          break;
        __e = iterator(__prev);
      }
      throw;
    }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    __link_nodes_at_back(__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_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
    ++__ds;
    __link_pointer __nl = __node->__as_link();
    iterator __r        = iterator(__nl);
    iterator __e        = __r;
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, __x)->__as_link();
      }
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
    } catch (...) {
      while (true) {
        __link_pointer __prev    = __e.__ptr_->__prev_;
        __node_pointer __current = __e.__ptr_->__as_node();
        this->__delete_node(__current);
        if (__prev == 0)
          break;
        __e = iterator(__prev);
      }
      throw;
    }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    __link_nodes(__base::__end_as_link(), __r.__ptr_, __e.__ptr_);
    __base::__sz() += __ds;
  }
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::splice(const_iterator __p, list& __c) {
  _LIBCPP_ASSERT_VALID_INPUT_RANGE(
      this != std::addressof(__c), "list::splice(iterator, list) called with this == &list");
  if (!__c.empty()) {
    __link_pointer __f = __c.__end_.__next_;
    __link_pointer __l = __c.__end_.__prev_;
    __base::__unlink_nodes(__f, __l);
    __link_nodes(__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.__ptr_ != __i.__ptr_ && __p.__ptr_ != __i.__ptr_->__next_) {
    __link_pointer __f = __i.__ptr_;
    __base::__unlink_nodes(__f, __f);
    __link_nodes(__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) {
    __link_pointer __first = __f.__ptr_;
    --__l;
    __link_pointer __last = __l.__ptr_;
    if (this != std::addressof(__c)) {
      size_type __s = std::distance(__f, __l) + 1;
      __c.__sz() -= __s;
      __base::__sz() += __s;
    }
    __base::__unlink_nodes(__first, __last);
    __link_nodes(__p.__ptr_, __first, __last);
  }
}

template <class _Tp, class _Alloc>
typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::remove(const value_type& __x) {
  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
  for (const_iterator __i = begin(), __e = end(); __i != __e;) {
    if (*__i == __x) {
      const_iterator __j = std::next(__i);
      for (; __j != __e && *__j == __x; ++__j)
        ;
      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
      __i = __j;
      if (__i != __e)
        ++__i;
    } else
      ++__i;
  }

  return (__remove_return_type)__deleted_nodes.size();
}

template <class _Tp, class _Alloc>
template <class _Pred>
typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::remove_if(_Pred __pred) {
  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
  for (iterator __i = begin(), __e = end(); __i != __e;) {
    if (__pred(*__i)) {
      iterator __j = std::next(__i);
      for (; __j != __e && __pred(*__j); ++__j)
        ;
      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
      __i = __j;
      if (__i != __e)
        ++__i;
    } else
      ++__i;
  }

  return (__remove_return_type)__deleted_nodes.size();
}

template <class _Tp, class _Alloc>
template <class _BinaryPred>
typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::unique(_BinaryPred __binary_pred) {
  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
  for (iterator __i = begin(), __e = end(); __i != __e;) {
    iterator __j = std::next(__i);
    for (; __j != __e && __binary_pred(*__i, *__j); ++__j)
      ;
    if (++__i != __j) {
      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
      __i = __j;
    }
  }

  return (__remove_return_type)__deleted_nodes.size();
}

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

template <class _Tp, class _Alloc>
template <class _Comp>
void list<_Tp, _Alloc>::merge(list& __c, _Comp __comp) {
  if (this != std::addressof(__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, (void)++__ds)
          ;
        __base::__sz() += __ds;
        __c.__sz() -= __ds;
        __link_pointer __f = __f2.__ptr_;
        __link_pointer __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 void list<_Tp, _Alloc>::sort() {
  sort(__less<>());
}

template <class _Tp, class _Alloc>
template <class _Comp>
inline 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)) {
      __link_pointer __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)
      ;
    __link_pointer __f = __f2.__ptr_;
    __link_pointer __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)
        ;
      __link_pointer __f = __f2.__ptr_;
      __link_pointer __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.__ptr_ != __e.__ptr_;) {
      std::swap(__i.__ptr_->__prev_, __i.__ptr_->__next_);
      __i.__ptr_ = __i.__ptr_->__prev_;
    }
    std::swap(__e.__ptr_->__prev_, __e.__ptr_->__next_);
  }
}

template <class _Tp, class _Alloc>
bool list<_Tp, _Alloc>::__invariants() const {
  return size() == std::distance(begin(), end());
}

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

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

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

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

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

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES)
#  include <__cxx03/algorithm>
#  include <__cxx03/atomic>
#  include <__cxx03/cstdint>
#  include <__cxx03/cstdlib>
#  include <__cxx03/functional>
#  include <__cxx03/iosfwd>
#  include <__cxx03/iterator>
#  include <__cxx03/stdexcept>
#  include <__cxx03/type_traits>
#  include <__cxx03/typeinfo>
#endif

#endif // _LIBCPP___CXX03_LIST
