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1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_LIST
11#define _LIBCPP_LIST
12
13/*
14    list synopsis
15
16namespace std
17{
18
19template <class T, class Alloc = allocator<T> >
20class list
21{
22public:
23
24    // types:
25    typedef T value_type;
26    typedef Alloc allocator_type;
27    typedef typename allocator_type::reference reference;
28    typedef typename allocator_type::const_reference const_reference;
29    typedef typename allocator_type::pointer pointer;
30    typedef typename allocator_type::const_pointer const_pointer;
31    typedef implementation-defined iterator;
32    typedef implementation-defined const_iterator;
33    typedef implementation-defined size_type;
34    typedef implementation-defined difference_type;
35    typedef reverse_iterator<iterator> reverse_iterator;
36    typedef reverse_iterator<const_iterator> const_reverse_iterator;
37
38    list()
39        noexcept(is_nothrow_default_constructible<allocator_type>::value);
40    explicit list(const allocator_type& a);
41    explicit list(size_type n);
42    explicit list(size_type n, const allocator_type& a); // C++14
43    list(size_type n, const value_type& value);
44    list(size_type n, const value_type& value, const allocator_type& a);
45    template <class Iter>
46        list(Iter first, Iter last);
47    template <class Iter>
48        list(Iter first, Iter last, const allocator_type& a);
49    template<container-compatible-range<T> R>
50      list(from_range_t, R&& rg, const Allocator& = Allocator()); // C++23
51    list(const list& x);
52    list(const list&, const allocator_type& a);
53    list(list&& x)
54        noexcept(is_nothrow_move_constructible<allocator_type>::value);
55    list(list&&, const allocator_type& a);
56    list(initializer_list<value_type>);
57    list(initializer_list<value_type>, const allocator_type& a);
58
59    ~list();
60
61    list& operator=(const list& x);
62    list& operator=(list&& x)
63        noexcept(
64             allocator_type::propagate_on_container_move_assignment::value &&
65             is_nothrow_move_assignable<allocator_type>::value);
66    list& operator=(initializer_list<value_type>);
67    template <class Iter>
68        void assign(Iter first, Iter last);
69    template<container-compatible-range<T> R>
70      void assign_range(R&& rg); // C++23
71    void assign(size_type n, const value_type& t);
72    void assign(initializer_list<value_type>);
73
74    allocator_type get_allocator() const noexcept;
75
76    iterator begin() noexcept;
77    const_iterator begin() const noexcept;
78    iterator end() noexcept;
79    const_iterator end() const noexcept;
80    reverse_iterator rbegin() noexcept;
81    const_reverse_iterator rbegin() const noexcept;
82    reverse_iterator rend() noexcept;
83    const_reverse_iterator rend() const noexcept;
84    const_iterator cbegin() const noexcept;
85    const_iterator cend() const noexcept;
86    const_reverse_iterator crbegin() const noexcept;
87    const_reverse_iterator crend() const noexcept;
88
89    reference front();
90    const_reference front() const;
91    reference back();
92    const_reference back() const;
93
94    bool empty() const noexcept;
95    size_type size() const noexcept;
96    size_type max_size() const noexcept;
97
98    template <class... Args>
99        reference emplace_front(Args&&... args); // reference in C++17
100    void pop_front();
101    template <class... Args>
102        reference emplace_back(Args&&... args);  // reference in C++17
103    void pop_back();
104    void push_front(const value_type& x);
105    void push_front(value_type&& x);
106    template<container-compatible-range<T> R>
107      void prepend_range(R&& rg); // C++23
108    void push_back(const value_type& x);
109    void push_back(value_type&& x);
110    template<container-compatible-range<T> R>
111      void append_range(R&& rg); // C++23
112    template <class... Args>
113        iterator emplace(const_iterator position, Args&&... args);
114    iterator insert(const_iterator position, const value_type& x);
115    iterator insert(const_iterator position, value_type&& x);
116    iterator insert(const_iterator position, size_type n, const value_type& x);
117    template <class Iter>
118        iterator insert(const_iterator position, Iter first, Iter last);
119    template<container-compatible-range<T> R>
120      iterator insert_range(const_iterator position, R&& rg); // C++23
121    iterator insert(const_iterator position, initializer_list<value_type> il);
122
123    iterator erase(const_iterator position);
124    iterator erase(const_iterator position, const_iterator last);
125
126    void resize(size_type sz);
127    void resize(size_type sz, const value_type& c);
128
129    void swap(list&)
130        noexcept(allocator_traits<allocator_type>::is_always_equal::value);  // C++17
131    void clear() noexcept;
132
133    void splice(const_iterator position, list& x);
134    void splice(const_iterator position, list&& x);
135    void splice(const_iterator position, list& x, const_iterator i);
136    void splice(const_iterator position, list&& x, const_iterator i);
137    void splice(const_iterator position, list& x, const_iterator first,
138                                                  const_iterator last);
139    void splice(const_iterator position, list&& x, const_iterator first,
140                                                  const_iterator last);
141
142    size_type remove(const value_type& value);       // void before C++20
143    template <class Pred>
144      size_type remove_if(Pred pred);                // void before C++20
145    size_type unique();                              // void before C++20
146    template <class BinaryPredicate>
147      size_type unique(BinaryPredicate binary_pred); // void before C++20
148    void merge(list& x);
149    void merge(list&& x);
150    template <class Compare>
151        void merge(list& x, Compare comp);
152    template <class Compare>
153        void merge(list&& x, Compare comp);
154    void sort();
155    template <class Compare>
156        void sort(Compare comp);
157    void reverse() noexcept;
158};
159
160
161template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
162    list(InputIterator, InputIterator, Allocator = Allocator())
163    -> list<typename iterator_traits<InputIterator>::value_type, Allocator>;  // C++17
164
165template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
166  list(from_range_t, R&&, Allocator = Allocator())
167    -> list<ranges::range_value_t<R>, Allocator>; // C++23
168
169template <class T, class Alloc>
170    bool operator==(const list<T,Alloc>& x, const list<T,Alloc>& y);
171template <class T, class Alloc>
172    bool operator< (const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
173template <class T, class Alloc>
174    bool operator!=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
175template <class T, class Alloc>
176    bool operator> (const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
177template <class T, class Alloc>
178    bool operator>=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
179template <class T, class Alloc>
180    bool operator<=(const list<T,Alloc>& x, const list<T,Alloc>& y);     // removed in C++20
181template<class T, class Allocator>
182  synth-three-way-result<T> operator<=>(const list<T, Allocator>& x,
183                                        const list<T, Allocator>& y);    // since C++20
184
185template <class T, class Alloc>
186    void swap(list<T,Alloc>& x, list<T,Alloc>& y)
187         noexcept(noexcept(x.swap(y)));
188
189template <class T, class Allocator, class U>
190    typename list<T, Allocator>::size_type
191    erase(list<T, Allocator>& c, const U& value);       // since C++20
192template <class T, class Allocator, class Predicate>
193    typename list<T, Allocator>::size_type
194    erase_if(list<T, Allocator>& c, Predicate pred);    // since C++20
195
196}  // std
197
198*/
199
200#include <__algorithm/comp.h>
201#include <__algorithm/equal.h>
202#include <__algorithm/lexicographical_compare.h>
203#include <__algorithm/lexicographical_compare_three_way.h>
204#include <__algorithm/min.h>
205#include <__assert>
206#include <__availability>
207#include <__config>
208#include <__format/enable_insertable.h>
209#include <__iterator/distance.h>
210#include <__iterator/iterator_traits.h>
211#include <__iterator/move_iterator.h>
212#include <__iterator/next.h>
213#include <__iterator/prev.h>
214#include <__iterator/reverse_iterator.h>
215#include <__memory/addressof.h>
216#include <__memory/allocation_guard.h>
217#include <__memory/allocator.h>
218#include <__memory/allocator_traits.h>
219#include <__memory/compressed_pair.h>
220#include <__memory/construct_at.h>
221#include <__memory/pointer_traits.h>
222#include <__memory/swap_allocator.h>
223#include <__memory_resource/polymorphic_allocator.h>
224#include <__ranges/access.h>
225#include <__ranges/concepts.h>
226#include <__ranges/container_compatible_range.h>
227#include <__ranges/from_range.h>
228#include <__type_traits/conditional.h>
229#include <__type_traits/is_allocator.h>
230#include <__type_traits/is_nothrow_default_constructible.h>
231#include <__type_traits/is_nothrow_move_assignable.h>
232#include <__type_traits/is_nothrow_move_constructible.h>
233#include <__type_traits/is_pointer.h>
234#include <__type_traits/is_same.h>
235#include <__type_traits/type_identity.h>
236#include <__utility/forward.h>
237#include <__utility/move.h>
238#include <__utility/swap.h>
239#include <cstring>
240#include <limits>
241#include <new> // __launder
242#include <version>
243
244// standard-mandated includes
245
246// [iterator.range]
247#include <__iterator/access.h>
248#include <__iterator/data.h>
249#include <__iterator/empty.h>
250#include <__iterator/reverse_access.h>
251#include <__iterator/size.h>
252
253// [list.syn]
254#include <compare>
255#include <initializer_list>
256
257#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
258#  pragma GCC system_header
259#endif
260
261_LIBCPP_PUSH_MACROS
262#include <__undef_macros>
263
264_LIBCPP_BEGIN_NAMESPACE_STD
265
266template <class _Tp, class _VoidPtr>
267struct __list_node;
268template <class _Tp, class _VoidPtr>
269struct __list_node_base;
270
271template <class _Tp, class _VoidPtr>
272struct __list_node_pointer_traits {
273  typedef __rebind_pointer_t<_VoidPtr, __list_node<_Tp, _VoidPtr> > __node_pointer;
274  typedef __rebind_pointer_t<_VoidPtr, __list_node_base<_Tp, _VoidPtr> > __base_pointer;
275
276#if defined(_LIBCPP_ABI_LIST_REMOVE_NODE_POINTER_UB)
277  typedef __base_pointer __link_pointer;
278#else
279  typedef __conditional_t<is_pointer<_VoidPtr>::value, __base_pointer, __node_pointer> __link_pointer;
280#endif
281
282  typedef __conditional_t<is_same<__link_pointer, __node_pointer>::value, __base_pointer, __node_pointer>
283      __non_link_pointer;
284
285  static _LIBCPP_HIDE_FROM_ABI __link_pointer __unsafe_link_pointer_cast(__link_pointer __p) { return __p; }
286
287  static _LIBCPP_HIDE_FROM_ABI __link_pointer __unsafe_link_pointer_cast(__non_link_pointer __p) {
288    return static_cast<__link_pointer>(static_cast<_VoidPtr>(__p));
289  }
290};
291
292template <class _Tp, class _VoidPtr>
293struct __list_node_base {
294  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
295  typedef typename _NodeTraits::__node_pointer __node_pointer;
296  typedef typename _NodeTraits::__base_pointer __base_pointer;
297  typedef typename _NodeTraits::__link_pointer __link_pointer;
298
299  __link_pointer __prev_;
300  __link_pointer __next_;
301
302  _LIBCPP_HIDE_FROM_ABI __list_node_base()
303      : __prev_(_NodeTraits::__unsafe_link_pointer_cast(__self())),
304        __next_(_NodeTraits::__unsafe_link_pointer_cast(__self())) {}
305
306  _LIBCPP_HIDE_FROM_ABI explicit __list_node_base(__link_pointer __prev, __link_pointer __next)
307      : __prev_(__prev), __next_(__next) {}
308
309  _LIBCPP_HIDE_FROM_ABI __base_pointer __self() { return pointer_traits<__base_pointer>::pointer_to(*this); }
310
311  _LIBCPP_HIDE_FROM_ABI __node_pointer __as_node() { return static_cast<__node_pointer>(__self()); }
312};
313
314template <class _Tp, class _VoidPtr>
315struct __list_node : public __list_node_base<_Tp, _VoidPtr> {
316  // We allow starting the lifetime of nodes without initializing the value held by the node,
317  // since that is handled by the list itself in order to be allocator-aware.
318#ifndef _LIBCPP_CXX03_LANG
319
320private:
321  union {
322    _Tp __value_;
323  };
324
325public:
326  _LIBCPP_HIDE_FROM_ABI _Tp& __get_value() { return __value_; }
327#else
328
329private:
330  _ALIGNAS_TYPE(_Tp) char __buffer_[sizeof(_Tp)];
331
332public:
333  _LIBCPP_HIDE_FROM_ABI _Tp& __get_value() { return *std::__launder(reinterpret_cast<_Tp*>(&__buffer_)); }
334#endif
335
336  typedef __list_node_base<_Tp, _VoidPtr> __base;
337  typedef typename __base::__link_pointer __link_pointer;
338
339  _LIBCPP_HIDE_FROM_ABI explicit __list_node(__link_pointer __prev, __link_pointer __next) : __base(__prev, __next) {}
340  _LIBCPP_HIDE_FROM_ABI ~__list_node() {}
341
342  _LIBCPP_HIDE_FROM_ABI __link_pointer __as_link() { return static_cast<__link_pointer>(__base::__self()); }
343};
344
345template <class _Tp, class _Alloc = allocator<_Tp> >
346class _LIBCPP_TEMPLATE_VIS list;
347template <class _Tp, class _Alloc>
348class __list_imp;
349template <class _Tp, class _VoidPtr>
350class _LIBCPP_TEMPLATE_VIS __list_const_iterator;
351
352template <class _Tp, class _VoidPtr>
353class _LIBCPP_TEMPLATE_VIS __list_iterator {
354  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
355  typedef typename _NodeTraits::__link_pointer __link_pointer;
356
357  __link_pointer __ptr_;
358
359  _LIBCPP_HIDE_FROM_ABI explicit __list_iterator(__link_pointer __p) _NOEXCEPT : __ptr_(__p) {}
360
361  template <class, class>
362  friend class list;
363  template <class, class>
364  friend class __list_imp;
365  template <class, class>
366  friend class __list_const_iterator;
367
368public:
369  typedef bidirectional_iterator_tag iterator_category;
370  typedef _Tp value_type;
371  typedef value_type& reference;
372  typedef __rebind_pointer_t<_VoidPtr, value_type> pointer;
373  typedef typename pointer_traits<pointer>::difference_type difference_type;
374
375  _LIBCPP_HIDE_FROM_ABI __list_iterator() _NOEXCEPT : __ptr_(nullptr) {}
376
377  _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __ptr_->__as_node()->__get_value(); }
378  _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
379    return pointer_traits<pointer>::pointer_to(__ptr_->__as_node()->__get_value());
380  }
381
382  _LIBCPP_HIDE_FROM_ABI __list_iterator& operator++() {
383    __ptr_ = __ptr_->__next_;
384    return *this;
385  }
386  _LIBCPP_HIDE_FROM_ABI __list_iterator operator++(int) {
387    __list_iterator __t(*this);
388    ++(*this);
389    return __t;
390  }
391
392  _LIBCPP_HIDE_FROM_ABI __list_iterator& operator--() {
393    __ptr_ = __ptr_->__prev_;
394    return *this;
395  }
396  _LIBCPP_HIDE_FROM_ABI __list_iterator operator--(int) {
397    __list_iterator __t(*this);
398    --(*this);
399    return __t;
400  }
401
402  friend _LIBCPP_HIDE_FROM_ABI bool operator==(const __list_iterator& __x, const __list_iterator& __y) {
403    return __x.__ptr_ == __y.__ptr_;
404  }
405  friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const __list_iterator& __x, const __list_iterator& __y) {
406    return !(__x == __y);
407  }
408};
409
410template <class _Tp, class _VoidPtr>
411class _LIBCPP_TEMPLATE_VIS __list_const_iterator {
412  typedef __list_node_pointer_traits<_Tp, _VoidPtr> _NodeTraits;
413  typedef typename _NodeTraits::__link_pointer __link_pointer;
414
415  __link_pointer __ptr_;
416
417  _LIBCPP_HIDE_FROM_ABI explicit __list_const_iterator(__link_pointer __p) _NOEXCEPT : __ptr_(__p) {}
418
419  template <class, class>
420  friend class list;
421  template <class, class>
422  friend class __list_imp;
423
424public:
425  typedef bidirectional_iterator_tag iterator_category;
426  typedef _Tp value_type;
427  typedef const value_type& reference;
428  typedef __rebind_pointer_t<_VoidPtr, const value_type> pointer;
429  typedef typename pointer_traits<pointer>::difference_type difference_type;
430
431  _LIBCPP_HIDE_FROM_ABI __list_const_iterator() _NOEXCEPT : __ptr_(nullptr) {}
432  _LIBCPP_HIDE_FROM_ABI __list_const_iterator(const __list_iterator<_Tp, _VoidPtr>& __p) _NOEXCEPT
433      : __ptr_(__p.__ptr_) {}
434
435  _LIBCPP_HIDE_FROM_ABI reference operator*() const { return __ptr_->__as_node()->__get_value(); }
436  _LIBCPP_HIDE_FROM_ABI pointer operator->() const {
437    return pointer_traits<pointer>::pointer_to(__ptr_->__as_node()->__get_value());
438  }
439
440  _LIBCPP_HIDE_FROM_ABI __list_const_iterator& operator++() {
441    __ptr_ = __ptr_->__next_;
442    return *this;
443  }
444  _LIBCPP_HIDE_FROM_ABI __list_const_iterator operator++(int) {
445    __list_const_iterator __t(*this);
446    ++(*this);
447    return __t;
448  }
449
450  _LIBCPP_HIDE_FROM_ABI __list_const_iterator& operator--() {
451    __ptr_ = __ptr_->__prev_;
452    return *this;
453  }
454  _LIBCPP_HIDE_FROM_ABI __list_const_iterator operator--(int) {
455    __list_const_iterator __t(*this);
456    --(*this);
457    return __t;
458  }
459
460  friend _LIBCPP_HIDE_FROM_ABI bool operator==(const __list_const_iterator& __x, const __list_const_iterator& __y) {
461    return __x.__ptr_ == __y.__ptr_;
462  }
463  friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const __list_const_iterator& __x, const __list_const_iterator& __y) {
464    return !(__x == __y);
465  }
466};
467
468template <class _Tp, class _Alloc>
469class __list_imp {
470  __list_imp(const __list_imp&);
471  __list_imp& operator=(const __list_imp&);
472
473public:
474  typedef _Alloc allocator_type;
475  typedef allocator_traits<allocator_type> __alloc_traits;
476  typedef typename __alloc_traits::size_type size_type;
477
478protected:
479  typedef _Tp value_type;
480  typedef typename __alloc_traits::void_pointer __void_pointer;
481  typedef __list_iterator<value_type, __void_pointer> iterator;
482  typedef __list_const_iterator<value_type, __void_pointer> const_iterator;
483  typedef __list_node_base<value_type, __void_pointer> __node_base;
484  typedef __list_node<value_type, __void_pointer> __node_type;
485  typedef __rebind_alloc<__alloc_traits, __node_type> __node_allocator;
486  typedef allocator_traits<__node_allocator> __node_alloc_traits;
487  typedef typename __node_alloc_traits::pointer __node_pointer;
488  typedef typename __node_alloc_traits::pointer __node_const_pointer;
489  typedef __list_node_pointer_traits<value_type, __void_pointer> __node_pointer_traits;
490  typedef typename __node_pointer_traits::__link_pointer __link_pointer;
491  typedef __link_pointer __link_const_pointer;
492  typedef typename __alloc_traits::pointer pointer;
493  typedef typename __alloc_traits::const_pointer const_pointer;
494  typedef typename __alloc_traits::difference_type difference_type;
495
496  typedef __rebind_alloc<__alloc_traits, __node_base> __node_base_allocator;
497  typedef typename allocator_traits<__node_base_allocator>::pointer __node_base_pointer;
498  static_assert((!is_same<allocator_type, __node_allocator>::value),
499                "internal allocator type must differ from user-specified "
500                "type; otherwise overload resolution breaks");
501
502  __node_base __end_;
503  __compressed_pair<size_type, __node_allocator> __size_alloc_;
504
505  _LIBCPP_HIDE_FROM_ABI __link_pointer __end_as_link() const _NOEXCEPT {
506    return __node_pointer_traits::__unsafe_link_pointer_cast(const_cast<__node_base&>(__end_).__self());
507  }
508
509  _LIBCPP_HIDE_FROM_ABI size_type& __sz() _NOEXCEPT { return __size_alloc_.first(); }
510  _LIBCPP_HIDE_FROM_ABI const size_type& __sz() const _NOEXCEPT { return __size_alloc_.first(); }
511  _LIBCPP_HIDE_FROM_ABI __node_allocator& __node_alloc() _NOEXCEPT { return __size_alloc_.second(); }
512  _LIBCPP_HIDE_FROM_ABI const __node_allocator& __node_alloc() const _NOEXCEPT { return __size_alloc_.second(); }
513
514  _LIBCPP_HIDE_FROM_ABI size_type __node_alloc_max_size() const _NOEXCEPT {
515    return __node_alloc_traits::max_size(__node_alloc());
516  }
517  _LIBCPP_HIDE_FROM_ABI static void __unlink_nodes(__link_pointer __f, __link_pointer __l) _NOEXCEPT;
518
519  _LIBCPP_HIDE_FROM_ABI __list_imp() _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value);
520  _LIBCPP_HIDE_FROM_ABI __list_imp(const allocator_type& __a);
521  _LIBCPP_HIDE_FROM_ABI __list_imp(const __node_allocator& __a);
522#ifndef _LIBCPP_CXX03_LANG
523  _LIBCPP_HIDE_FROM_ABI __list_imp(__node_allocator&& __a) _NOEXCEPT;
524#endif
525  _LIBCPP_HIDE_FROM_ABI ~__list_imp();
526  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT;
527  _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return __sz() == 0; }
528
529  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return iterator(__end_.__next_); }
530  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return const_iterator(__end_.__next_); }
531  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return iterator(__end_as_link()); }
532  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return const_iterator(__end_as_link()); }
533
534  _LIBCPP_HIDE_FROM_ABI void swap(__list_imp& __c)
535#if _LIBCPP_STD_VER >= 14
536      _NOEXCEPT;
537#else
538      _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable<allocator_type>::value);
539#endif
540
541  _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __list_imp& __c) {
542    __copy_assign_alloc(
543        __c, integral_constant<bool, __node_alloc_traits::propagate_on_container_copy_assignment::value>());
544  }
545
546  _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__list_imp& __c)
547      _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_move_assignment::value ||
548                 is_nothrow_move_assignable<__node_allocator>::value) {
549    __move_assign_alloc(
550        __c, integral_constant<bool, __node_alloc_traits::propagate_on_container_move_assignment::value>());
551  }
552
553  template <class... _Args>
554  _LIBCPP_HIDE_FROM_ABI __node_pointer __create_node(__link_pointer __prev, __link_pointer __next, _Args&&... __args) {
555    __node_allocator& __alloc = __node_alloc();
556    __allocation_guard<__node_allocator> __guard(__alloc, 1);
557    // Begin the lifetime of the node itself. Note that this doesn't begin the lifetime of the value
558    // held inside the node, since we need to use the allocator's construct() method for that.
559    //
560    // We don't use the allocator's construct() method to construct the node itself since the
561    // Cpp17FooInsertable named requirements don't require the allocator's construct() method
562    // to work on anything other than the value_type.
563    std::__construct_at(std::addressof(*__guard.__get()), __prev, __next);
564
565    // Now construct the value_type using the allocator's construct() method.
566    __node_alloc_traits::construct(
567        __alloc, std::addressof(__guard.__get()->__get_value()), std::forward<_Args>(__args)...);
568    return __guard.__release_ptr();
569  }
570
571  template <class... _Args>
572  _LIBCPP_HIDE_FROM_ABI void __delete_node(__node_pointer __node) {
573    // For the same reason as above, we use the allocator's destroy() method for the value_type,
574    // but not for the node itself.
575    __node_allocator& __alloc = __node_alloc();
576    __node_alloc_traits::destroy(__alloc, std::addressof(__node->__get_value()));
577    std::__destroy_at(std::addressof(*__node));
578    __node_alloc_traits::deallocate(__alloc, __node, 1);
579  }
580
581private:
582  _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __list_imp& __c, true_type) {
583    if (__node_alloc() != __c.__node_alloc())
584      clear();
585    __node_alloc() = __c.__node_alloc();
586  }
587
588  _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const __list_imp&, false_type) {}
589
590  _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__list_imp& __c, true_type)
591      _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value) {
592    __node_alloc() = std::move(__c.__node_alloc());
593  }
594
595  _LIBCPP_HIDE_FROM_ABI void __move_assign_alloc(__list_imp&, false_type) _NOEXCEPT {}
596};
597
598// Unlink nodes [__f, __l]
599template <class _Tp, class _Alloc>
600inline void __list_imp<_Tp, _Alloc>::__unlink_nodes(__link_pointer __f, __link_pointer __l) _NOEXCEPT {
601  __f->__prev_->__next_ = __l->__next_;
602  __l->__next_->__prev_ = __f->__prev_;
603}
604
605template <class _Tp, class _Alloc>
606inline __list_imp<_Tp, _Alloc>::__list_imp() _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value)
607    : __size_alloc_(0, __default_init_tag()) {}
608
609template <class _Tp, class _Alloc>
610inline __list_imp<_Tp, _Alloc>::__list_imp(const allocator_type& __a) : __size_alloc_(0, __node_allocator(__a)) {}
611
612template <class _Tp, class _Alloc>
613inline __list_imp<_Tp, _Alloc>::__list_imp(const __node_allocator& __a) : __size_alloc_(0, __a) {}
614
615#ifndef _LIBCPP_CXX03_LANG
616template <class _Tp, class _Alloc>
617inline __list_imp<_Tp, _Alloc>::__list_imp(__node_allocator&& __a) _NOEXCEPT : __size_alloc_(0, std::move(__a)) {}
618#endif
619
620template <class _Tp, class _Alloc>
621__list_imp<_Tp, _Alloc>::~__list_imp() {
622  clear();
623}
624
625template <class _Tp, class _Alloc>
626void __list_imp<_Tp, _Alloc>::clear() _NOEXCEPT {
627  if (!empty()) {
628    __link_pointer __f = __end_.__next_;
629    __link_pointer __l = __end_as_link();
630    __unlink_nodes(__f, __l->__prev_);
631    __sz() = 0;
632    while (__f != __l) {
633      __node_pointer __np = __f->__as_node();
634      __f                 = __f->__next_;
635      __delete_node(__np);
636    }
637  }
638}
639
640template <class _Tp, class _Alloc>
641void __list_imp<_Tp, _Alloc>::swap(__list_imp& __c)
642#if _LIBCPP_STD_VER >= 14
643    _NOEXCEPT
644#else
645    _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable<allocator_type>::value)
646#endif
647{
648  _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
649      __alloc_traits::propagate_on_container_swap::value || this->__node_alloc() == __c.__node_alloc(),
650      "list::swap: Either propagate_on_container_swap must be true"
651      " or the allocators must compare equal");
652  using std::swap;
653  std::__swap_allocator(__node_alloc(), __c.__node_alloc());
654  swap(__sz(), __c.__sz());
655  swap(__end_, __c.__end_);
656  if (__sz() == 0)
657    __end_.__next_ = __end_.__prev_ = __end_as_link();
658  else
659    __end_.__prev_->__next_ = __end_.__next_->__prev_ = __end_as_link();
660  if (__c.__sz() == 0)
661    __c.__end_.__next_ = __c.__end_.__prev_ = __c.__end_as_link();
662  else
663    __c.__end_.__prev_->__next_ = __c.__end_.__next_->__prev_ = __c.__end_as_link();
664}
665
666template <class _Tp, class _Alloc /*= allocator<_Tp>*/>
667class _LIBCPP_TEMPLATE_VIS list : private __list_imp<_Tp, _Alloc> {
668  typedef __list_imp<_Tp, _Alloc> base;
669  typedef typename base::__node_type __node_type;
670  typedef typename base::__node_allocator __node_allocator;
671  typedef typename base::__node_pointer __node_pointer;
672  typedef typename base::__node_alloc_traits __node_alloc_traits;
673  typedef typename base::__node_base __node_base;
674  typedef typename base::__node_base_pointer __node_base_pointer;
675  typedef typename base::__link_pointer __link_pointer;
676
677public:
678  typedef _Tp value_type;
679  typedef _Alloc allocator_type;
680  static_assert((is_same<value_type, typename allocator_type::value_type>::value),
681                "Allocator::value_type must be same type as value_type");
682  typedef value_type& reference;
683  typedef const value_type& const_reference;
684  typedef typename base::pointer pointer;
685  typedef typename base::const_pointer const_pointer;
686  typedef typename base::size_type size_type;
687  typedef typename base::difference_type difference_type;
688  typedef typename base::iterator iterator;
689  typedef typename base::const_iterator const_iterator;
690  typedef std::reverse_iterator<iterator> reverse_iterator;
691  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
692#if _LIBCPP_STD_VER >= 20
693  typedef size_type __remove_return_type;
694#else
695  typedef void __remove_return_type;
696#endif
697
698  static_assert(is_same<allocator_type, __rebind_alloc<allocator_traits<allocator_type>, value_type> >::value,
699                "[allocator.requirements] states that rebinding an allocator to the same type should result in the "
700                "original allocator");
701
702  _LIBCPP_HIDE_FROM_ABI list() _NOEXCEPT_(is_nothrow_default_constructible<__node_allocator>::value) {}
703  _LIBCPP_HIDE_FROM_ABI explicit list(const allocator_type& __a) : base(__a) {}
704  _LIBCPP_HIDE_FROM_ABI explicit list(size_type __n);
705#if _LIBCPP_STD_VER >= 14
706  _LIBCPP_HIDE_FROM_ABI explicit list(size_type __n, const allocator_type& __a);
707#endif
708  _LIBCPP_HIDE_FROM_ABI list(size_type __n, const value_type& __x);
709  template <__enable_if_t<__is_allocator<_Alloc>::value, int> = 0>
710  _LIBCPP_HIDE_FROM_ABI list(size_type __n, const value_type& __x, const allocator_type& __a) : base(__a) {
711    for (; __n > 0; --__n)
712      push_back(__x);
713  }
714
715  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
716  _LIBCPP_HIDE_FROM_ABI list(_InpIter __f, _InpIter __l);
717
718  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
719  _LIBCPP_HIDE_FROM_ABI list(_InpIter __f, _InpIter __l, const allocator_type& __a);
720
721#if _LIBCPP_STD_VER >= 23
722  template <_ContainerCompatibleRange<_Tp> _Range>
723  _LIBCPP_HIDE_FROM_ABI list(from_range_t, _Range&& __range, const allocator_type& __a = allocator_type()) : base(__a) {
724    prepend_range(std::forward<_Range>(__range));
725  }
726#endif
727
728  _LIBCPP_HIDE_FROM_ABI list(const list& __c);
729  _LIBCPP_HIDE_FROM_ABI list(const list& __c, const __type_identity_t<allocator_type>& __a);
730  _LIBCPP_HIDE_FROM_ABI list& operator=(const list& __c);
731#ifndef _LIBCPP_CXX03_LANG
732  _LIBCPP_HIDE_FROM_ABI list(initializer_list<value_type> __il);
733  _LIBCPP_HIDE_FROM_ABI list(initializer_list<value_type> __il, const allocator_type& __a);
734
735  _LIBCPP_HIDE_FROM_ABI list(list&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__node_allocator>::value);
736  _LIBCPP_HIDE_FROM_ABI list(list&& __c, const __type_identity_t<allocator_type>& __a);
737  _LIBCPP_HIDE_FROM_ABI list& operator=(list&& __c)
738      _NOEXCEPT_(__node_alloc_traits::propagate_on_container_move_assignment::value&&
739                     is_nothrow_move_assignable<__node_allocator>::value);
740
741  _LIBCPP_HIDE_FROM_ABI list& operator=(initializer_list<value_type> __il) {
742    assign(__il.begin(), __il.end());
743    return *this;
744  }
745
746  _LIBCPP_HIDE_FROM_ABI void assign(initializer_list<value_type> __il) { assign(__il.begin(), __il.end()); }
747#endif // _LIBCPP_CXX03_LANG
748
749  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
750  _LIBCPP_HIDE_FROM_ABI void assign(_InpIter __f, _InpIter __l);
751
752#if _LIBCPP_STD_VER >= 23
753  template <_ContainerCompatibleRange<_Tp> _Range>
754  _LIBCPP_HIDE_FROM_ABI void assign_range(_Range&& __range) {
755    __assign_with_sentinel(ranges::begin(__range), ranges::end(__range));
756  }
757#endif
758
759  _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __x);
760
761  _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const _NOEXCEPT;
762
763  _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return base::__sz(); }
764  _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI bool empty() const _NOEXCEPT { return base::empty(); }
765  _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
766    return std::min<size_type>(base::__node_alloc_max_size(), numeric_limits<difference_type >::max());
767  }
768
769  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT { return base::begin(); }
770  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return base::begin(); }
771  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT { return base::end(); }
772  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return base::end(); }
773  _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT { return base::begin(); }
774  _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT { return base::end(); }
775
776  _LIBCPP_HIDE_FROM_ABI reverse_iterator rbegin() _NOEXCEPT { return reverse_iterator(end()); }
777  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
778  _LIBCPP_HIDE_FROM_ABI reverse_iterator rend() _NOEXCEPT { return reverse_iterator(begin()); }
779  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT { return const_reverse_iterator(begin()); }
780  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT { return const_reverse_iterator(end()); }
781  _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT { return const_reverse_iterator(begin()); }
782
783  _LIBCPP_HIDE_FROM_ABI reference front() {
784    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
785    return base::__end_.__next_->__as_node()->__get_value();
786  }
787  _LIBCPP_HIDE_FROM_ABI const_reference front() const {
788    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::front called on empty list");
789    return base::__end_.__next_->__as_node()->__get_value();
790  }
791  _LIBCPP_HIDE_FROM_ABI reference back() {
792    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
793    return base::__end_.__prev_->__as_node()->__get_value();
794  }
795  _LIBCPP_HIDE_FROM_ABI const_reference back() const {
796    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::back called on empty list");
797    return base::__end_.__prev_->__as_node()->__get_value();
798  }
799
800#ifndef _LIBCPP_CXX03_LANG
801  _LIBCPP_HIDE_FROM_ABI void push_front(value_type&& __x);
802  _LIBCPP_HIDE_FROM_ABI void push_back(value_type&& __x);
803
804#  if _LIBCPP_STD_VER >= 23
805  template <_ContainerCompatibleRange<_Tp> _Range>
806  _LIBCPP_HIDE_FROM_ABI void prepend_range(_Range&& __range) {
807    insert_range(begin(), std::forward<_Range>(__range));
808  }
809
810  template <_ContainerCompatibleRange<_Tp> _Range>
811  _LIBCPP_HIDE_FROM_ABI void append_range(_Range&& __range) {
812    insert_range(end(), std::forward<_Range>(__range));
813  }
814#  endif
815
816  template <class... _Args>
817#  if _LIBCPP_STD_VER >= 17
818  _LIBCPP_HIDE_FROM_ABI reference emplace_front(_Args&&... __args);
819#  else
820  _LIBCPP_HIDE_FROM_ABI void emplace_front(_Args&&... __args);
821#  endif
822  template <class... _Args>
823#  if _LIBCPP_STD_VER >= 17
824  _LIBCPP_HIDE_FROM_ABI reference emplace_back(_Args&&... __args);
825#  else
826  _LIBCPP_HIDE_FROM_ABI void emplace_back(_Args&&... __args);
827#  endif
828  template <class... _Args>
829  _LIBCPP_HIDE_FROM_ABI iterator emplace(const_iterator __p, _Args&&... __args);
830
831  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __x);
832
833  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, initializer_list<value_type> __il) {
834    return insert(__p, __il.begin(), __il.end());
835  }
836#endif // _LIBCPP_CXX03_LANG
837
838  _LIBCPP_HIDE_FROM_ABI void push_front(const value_type& __x);
839  _LIBCPP_HIDE_FROM_ABI void push_back(const value_type& __x);
840
841#ifndef _LIBCPP_CXX03_LANG
842  template <class _Arg>
843  _LIBCPP_HIDE_FROM_ABI void __emplace_back(_Arg&& __arg) {
844    emplace_back(std::forward<_Arg>(__arg));
845  }
846#else
847  _LIBCPP_HIDE_FROM_ABI void __emplace_back(value_type const& __arg) { push_back(__arg); }
848#endif
849
850  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __x);
851  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, size_type __n, const value_type& __x);
852
853  template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> = 0>
854  _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _InpIter __f, _InpIter __l);
855
856#if _LIBCPP_STD_VER >= 23
857  template <_ContainerCompatibleRange<_Tp> _Range>
858  _LIBCPP_HIDE_FROM_ABI iterator insert_range(const_iterator __position, _Range&& __range) {
859    return __insert_with_sentinel(__position, ranges::begin(__range), ranges::end(__range));
860  }
861#endif
862
863  _LIBCPP_HIDE_FROM_ABI void swap(list& __c)
864#if _LIBCPP_STD_VER >= 14
865      _NOEXCEPT
866#else
867      _NOEXCEPT_(!__node_alloc_traits::propagate_on_container_swap::value ||
868                 __is_nothrow_swappable<__node_allocator>::value)
869#endif
870  {
871    base::swap(__c);
872  }
873  _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT { base::clear(); }
874
875  _LIBCPP_HIDE_FROM_ABI void pop_front();
876  _LIBCPP_HIDE_FROM_ABI void pop_back();
877
878  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p);
879  _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l);
880
881  _LIBCPP_HIDE_FROM_ABI void resize(size_type __n);
882  _LIBCPP_HIDE_FROM_ABI void resize(size_type __n, const value_type& __x);
883
884  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c);
885#ifndef _LIBCPP_CXX03_LANG
886  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list&& __c) { splice(__p, __c); }
887  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list&& __c, const_iterator __i) { splice(__p, __c, __i); }
888  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list&& __c, const_iterator __f, const_iterator __l) {
889    splice(__p, __c, __f, __l);
890  }
891#endif
892  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c, const_iterator __i);
893  _LIBCPP_HIDE_FROM_ABI void splice(const_iterator __p, list& __c, const_iterator __f, const_iterator __l);
894
895  _LIBCPP_HIDE_FROM_ABI __remove_return_type remove(const value_type& __x);
896  template <class _Pred>
897  _LIBCPP_HIDE_FROM_ABI __remove_return_type remove_if(_Pred __pred);
898  _LIBCPP_HIDE_FROM_ABI __remove_return_type unique() { return unique(__equal_to()); }
899  template <class _BinaryPred>
900  _LIBCPP_HIDE_FROM_ABI __remove_return_type unique(_BinaryPred __binary_pred);
901  _LIBCPP_HIDE_FROM_ABI void merge(list& __c);
902#ifndef _LIBCPP_CXX03_LANG
903  _LIBCPP_HIDE_FROM_ABI void merge(list&& __c) { merge(__c); }
904
905  template <class _Comp>
906  _LIBCPP_HIDE_FROM_ABI void merge(list&& __c, _Comp __comp) {
907    merge(__c, __comp);
908  }
909#endif
910  template <class _Comp>
911  _LIBCPP_HIDE_FROM_ABI void merge(list& __c, _Comp __comp);
912
913  _LIBCPP_HIDE_FROM_ABI void sort();
914  template <class _Comp>
915  _LIBCPP_HIDE_FROM_ABI void sort(_Comp __comp);
916
917  _LIBCPP_HIDE_FROM_ABI void reverse() _NOEXCEPT;
918
919  _LIBCPP_HIDE_FROM_ABI bool __invariants() const;
920
921private:
922  template <class _Iterator, class _Sentinel>
923  _LIBCPP_HIDE_FROM_ABI void __assign_with_sentinel(_Iterator __f, _Sentinel __l);
924
925  template <class _Iterator, class _Sentinel>
926  _LIBCPP_HIDE_FROM_ABI iterator __insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l);
927
928  _LIBCPP_HIDE_FROM_ABI static void __link_nodes(__link_pointer __p, __link_pointer __f, __link_pointer __l);
929  _LIBCPP_HIDE_FROM_ABI void __link_nodes_at_front(__link_pointer __f, __link_pointer __l);
930  _LIBCPP_HIDE_FROM_ABI void __link_nodes_at_back(__link_pointer __f, __link_pointer __l);
931  _LIBCPP_HIDE_FROM_ABI iterator __iterator(size_type __n);
932  // TODO: Make this _LIBCPP_HIDE_FROM_ABI
933  template <class _Comp>
934  _LIBCPP_HIDDEN static iterator __sort(iterator __f1, iterator __e2, size_type __n, _Comp& __comp);
935
936  _LIBCPP_HIDE_FROM_ABI void __move_assign(list& __c, true_type)
937      _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value);
938  _LIBCPP_HIDE_FROM_ABI void __move_assign(list& __c, false_type);
939};
940
941#if _LIBCPP_STD_VER >= 17
942template <class _InputIterator,
943          class _Alloc = allocator<__iter_value_type<_InputIterator>>,
944          class        = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
945          class        = enable_if_t<__is_allocator<_Alloc>::value> >
946list(_InputIterator, _InputIterator) -> list<__iter_value_type<_InputIterator>, _Alloc>;
947
948template <class _InputIterator,
949          class _Alloc,
950          class = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
951          class = enable_if_t<__is_allocator<_Alloc>::value> >
952list(_InputIterator, _InputIterator, _Alloc) -> list<__iter_value_type<_InputIterator>, _Alloc>;
953#endif
954
955#if _LIBCPP_STD_VER >= 23
956template <ranges::input_range _Range,
957          class _Alloc = allocator<ranges::range_value_t<_Range>>,
958          class        = enable_if_t<__is_allocator<_Alloc>::value> >
959list(from_range_t, _Range&&, _Alloc = _Alloc()) -> list<ranges::range_value_t<_Range>, _Alloc>;
960#endif
961
962// Link in nodes [__f, __l] just prior to __p
963template <class _Tp, class _Alloc>
964inline void list<_Tp, _Alloc>::__link_nodes(__link_pointer __p, __link_pointer __f, __link_pointer __l) {
965  __p->__prev_->__next_ = __f;
966  __f->__prev_          = __p->__prev_;
967  __p->__prev_          = __l;
968  __l->__next_          = __p;
969}
970
971// Link in nodes [__f, __l] at the front of the list
972template <class _Tp, class _Alloc>
973inline void list<_Tp, _Alloc>::__link_nodes_at_front(__link_pointer __f, __link_pointer __l) {
974  __f->__prev_          = base::__end_as_link();
975  __l->__next_          = base::__end_.__next_;
976  __l->__next_->__prev_ = __l;
977  base::__end_.__next_  = __f;
978}
979
980// Link in nodes [__f, __l] at the back of the list
981template <class _Tp, class _Alloc>
982inline void list<_Tp, _Alloc>::__link_nodes_at_back(__link_pointer __f, __link_pointer __l) {
983  __l->__next_          = base::__end_as_link();
984  __f->__prev_          = base::__end_.__prev_;
985  __f->__prev_->__next_ = __f;
986  base::__end_.__prev_  = __l;
987}
988
989template <class _Tp, class _Alloc>
990inline typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::__iterator(size_type __n) {
991  return __n <= base::__sz() / 2 ? std::next(begin(), __n) : std::prev(end(), base::__sz() - __n);
992}
993
994template <class _Tp, class _Alloc>
995list<_Tp, _Alloc>::list(size_type __n) {
996  for (; __n > 0; --__n)
997#ifndef _LIBCPP_CXX03_LANG
998    emplace_back();
999#else
1000    push_back(value_type());
1001#endif
1002}
1003
1004#if _LIBCPP_STD_VER >= 14
1005template <class _Tp, class _Alloc>
1006list<_Tp, _Alloc>::list(size_type __n, const allocator_type& __a) : base(__a) {
1007  for (; __n > 0; --__n)
1008    emplace_back();
1009}
1010#endif
1011
1012template <class _Tp, class _Alloc>
1013list<_Tp, _Alloc>::list(size_type __n, const value_type& __x) {
1014  for (; __n > 0; --__n)
1015    push_back(__x);
1016}
1017
1018template <class _Tp, class _Alloc>
1019template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
1020list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l) {
1021  for (; __f != __l; ++__f)
1022    __emplace_back(*__f);
1023}
1024
1025template <class _Tp, class _Alloc>
1026template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
1027list<_Tp, _Alloc>::list(_InpIter __f, _InpIter __l, const allocator_type& __a) : base(__a) {
1028  for (; __f != __l; ++__f)
1029    __emplace_back(*__f);
1030}
1031
1032template <class _Tp, class _Alloc>
1033list<_Tp, _Alloc>::list(const list& __c)
1034    : base(__node_alloc_traits::select_on_container_copy_construction(__c.__node_alloc())) {
1035  for (const_iterator __i = __c.begin(), __e = __c.end(); __i != __e; ++__i)
1036    push_back(*__i);
1037}
1038
1039template <class _Tp, class _Alloc>
1040list<_Tp, _Alloc>::list(const list& __c, const __type_identity_t<allocator_type>& __a) : base(__a) {
1041  for (const_iterator __i = __c.begin(), __e = __c.end(); __i != __e; ++__i)
1042    push_back(*__i);
1043}
1044
1045#ifndef _LIBCPP_CXX03_LANG
1046
1047template <class _Tp, class _Alloc>
1048list<_Tp, _Alloc>::list(initializer_list<value_type> __il, const allocator_type& __a) : base(__a) {
1049  for (typename initializer_list<value_type>::const_iterator __i = __il.begin(), __e = __il.end(); __i != __e; ++__i)
1050    push_back(*__i);
1051}
1052
1053template <class _Tp, class _Alloc>
1054list<_Tp, _Alloc>::list(initializer_list<value_type> __il) {
1055  for (typename initializer_list<value_type>::const_iterator __i = __il.begin(), __e = __il.end(); __i != __e; ++__i)
1056    push_back(*__i);
1057}
1058
1059template <class _Tp, class _Alloc>
1060inline list<_Tp, _Alloc>::list(list&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__node_allocator>::value)
1061    : base(std::move(__c.__node_alloc())) {
1062  splice(end(), __c);
1063}
1064
1065template <class _Tp, class _Alloc>
1066inline list<_Tp, _Alloc>::list(list&& __c, const __type_identity_t<allocator_type>& __a) : base(__a) {
1067  if (__a == __c.get_allocator())
1068    splice(end(), __c);
1069  else {
1070    typedef move_iterator<iterator> _Ip;
1071    assign(_Ip(__c.begin()), _Ip(__c.end()));
1072  }
1073}
1074
1075template <class _Tp, class _Alloc>
1076inline list<_Tp, _Alloc>& list<_Tp, _Alloc>::operator=(list&& __c)
1077    _NOEXCEPT_(__node_alloc_traits::propagate_on_container_move_assignment::value&&
1078                   is_nothrow_move_assignable<__node_allocator>::value) {
1079  __move_assign(__c, integral_constant<bool, __node_alloc_traits::propagate_on_container_move_assignment::value>());
1080  return *this;
1081}
1082
1083template <class _Tp, class _Alloc>
1084void list<_Tp, _Alloc>::__move_assign(list& __c, false_type) {
1085  if (base::__node_alloc() != __c.__node_alloc()) {
1086    typedef move_iterator<iterator> _Ip;
1087    assign(_Ip(__c.begin()), _Ip(__c.end()));
1088  } else
1089    __move_assign(__c, true_type());
1090}
1091
1092template <class _Tp, class _Alloc>
1093void list<_Tp, _Alloc>::__move_assign(list& __c, true_type)
1094    _NOEXCEPT_(is_nothrow_move_assignable<__node_allocator>::value) {
1095  clear();
1096  base::__move_assign_alloc(__c);
1097  splice(end(), __c);
1098}
1099
1100#endif // _LIBCPP_CXX03_LANG
1101
1102template <class _Tp, class _Alloc>
1103inline list<_Tp, _Alloc>& list<_Tp, _Alloc>::operator=(const list& __c) {
1104  if (this != std::addressof(__c)) {
1105    base::__copy_assign_alloc(__c);
1106    assign(__c.begin(), __c.end());
1107  }
1108  return *this;
1109}
1110
1111template <class _Tp, class _Alloc>
1112template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
1113void list<_Tp, _Alloc>::assign(_InpIter __f, _InpIter __l) {
1114  __assign_with_sentinel(__f, __l);
1115}
1116
1117template <class _Tp, class _Alloc>
1118template <class _Iterator, class _Sentinel>
1119_LIBCPP_HIDE_FROM_ABI void list<_Tp, _Alloc>::__assign_with_sentinel(_Iterator __f, _Sentinel __l) {
1120  iterator __i = begin();
1121  iterator __e = end();
1122  for (; __f != __l && __i != __e; ++__f, (void)++__i)
1123    *__i = *__f;
1124  if (__i == __e)
1125    __insert_with_sentinel(__e, std::move(__f), std::move(__l));
1126  else
1127    erase(__i, __e);
1128}
1129
1130template <class _Tp, class _Alloc>
1131void list<_Tp, _Alloc>::assign(size_type __n, const value_type& __x) {
1132  iterator __i = begin();
1133  iterator __e = end();
1134  for (; __n > 0 && __i != __e; --__n, (void)++__i)
1135    *__i = __x;
1136  if (__i == __e)
1137    insert(__e, __n, __x);
1138  else
1139    erase(__i, __e);
1140}
1141
1142template <class _Tp, class _Alloc>
1143inline _Alloc list<_Tp, _Alloc>::get_allocator() const _NOEXCEPT {
1144  return allocator_type(base::__node_alloc());
1145}
1146
1147template <class _Tp, class _Alloc>
1148typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::insert(const_iterator __p, const value_type& __x) {
1149  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
1150  __link_nodes(__p.__ptr_, __node->__as_link(), __node->__as_link());
1151  ++base::__sz();
1152  return iterator(__node->__as_link());
1153}
1154
1155template <class _Tp, class _Alloc>
1156typename list<_Tp, _Alloc>::iterator
1157list<_Tp, _Alloc>::insert(const_iterator __p, size_type __n, const value_type& __x) {
1158  iterator __r(__p.__ptr_);
1159  if (__n > 0) {
1160    size_type __ds        = 0;
1161    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
1162    ++__ds;
1163    __r          = iterator(__node->__as_link());
1164    iterator __e = __r;
1165#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1166    try {
1167#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1168      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
1169        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, __x)->__as_link();
1170      }
1171#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1172    } catch (...) {
1173      while (true) {
1174        __link_pointer __prev    = __e.__ptr_->__prev_;
1175        __node_pointer __current = __e.__ptr_->__as_node();
1176        this->__delete_node(__current);
1177        if (__prev == 0)
1178          break;
1179        __e = iterator(__prev);
1180      }
1181      throw;
1182    }
1183#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1184    __link_nodes(__p.__ptr_, __r.__ptr_, __e.__ptr_);
1185    base::__sz() += __ds;
1186  }
1187  return __r;
1188}
1189
1190template <class _Tp, class _Alloc>
1191template <class _InpIter, __enable_if_t<__has_input_iterator_category<_InpIter>::value, int> >
1192typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::insert(const_iterator __p, _InpIter __f, _InpIter __l) {
1193  return __insert_with_sentinel(__p, __f, __l);
1194}
1195
1196template <class _Tp, class _Alloc>
1197template <class _Iterator, class _Sentinel>
1198_LIBCPP_HIDE_FROM_ABI typename list<_Tp, _Alloc>::iterator
1199list<_Tp, _Alloc>::__insert_with_sentinel(const_iterator __p, _Iterator __f, _Sentinel __l) {
1200  iterator __r(__p.__ptr_);
1201  if (__f != __l) {
1202    size_type __ds        = 0;
1203    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, *__f);
1204    ++__ds;
1205    __r          = iterator(__node->__as_link());
1206    iterator __e = __r;
1207#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1208    try {
1209#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1210      for (++__f; __f != __l; ++__f, (void)++__e, ++__ds) {
1211        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, *__f)->__as_link();
1212      }
1213#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1214    } catch (...) {
1215      while (true) {
1216        __link_pointer __prev    = __e.__ptr_->__prev_;
1217        __node_pointer __current = __e.__ptr_->__as_node();
1218        this->__delete_node(__current);
1219        if (__prev == 0)
1220          break;
1221        __e = iterator(__prev);
1222      }
1223      throw;
1224    }
1225#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1226    __link_nodes(__p.__ptr_, __r.__ptr_, __e.__ptr_);
1227    base::__sz() += __ds;
1228  }
1229  return __r;
1230}
1231
1232template <class _Tp, class _Alloc>
1233void list<_Tp, _Alloc>::push_front(const value_type& __x) {
1234  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
1235  __link_pointer __nl   = __node->__as_link();
1236  __link_nodes_at_front(__nl, __nl);
1237  ++base::__sz();
1238}
1239
1240template <class _Tp, class _Alloc>
1241void list<_Tp, _Alloc>::push_back(const value_type& __x) {
1242  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
1243  __link_pointer __nl   = __node->__as_link();
1244  __link_nodes_at_back(__nl, __nl);
1245  ++base::__sz();
1246}
1247
1248#ifndef _LIBCPP_CXX03_LANG
1249
1250template <class _Tp, class _Alloc>
1251void list<_Tp, _Alloc>::push_front(value_type&& __x) {
1252  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::move(__x));
1253  __link_pointer __nl   = __node->__as_link();
1254  __link_nodes_at_front(__nl, __nl);
1255  ++base::__sz();
1256}
1257
1258template <class _Tp, class _Alloc>
1259void list<_Tp, _Alloc>::push_back(value_type&& __x) {
1260  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::move(__x));
1261  __link_pointer __nl   = __node->__as_link();
1262  __link_nodes_at_back(__nl, __nl);
1263  ++base::__sz();
1264}
1265
1266template <class _Tp, class _Alloc>
1267template <class... _Args>
1268#  if _LIBCPP_STD_VER >= 17
1269typename list<_Tp, _Alloc>::reference
1270#  else
1271void
1272#  endif
1273list<_Tp, _Alloc>::emplace_front(_Args&&... __args) {
1274  __node_pointer __node =
1275      this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::forward<_Args>(__args)...);
1276  __link_pointer __nl = __node->__as_link();
1277  __link_nodes_at_front(__nl, __nl);
1278  ++base::__sz();
1279#  if _LIBCPP_STD_VER >= 17
1280  return __node->__get_value();
1281#  endif
1282}
1283
1284template <class _Tp, class _Alloc>
1285template <class... _Args>
1286#  if _LIBCPP_STD_VER >= 17
1287typename list<_Tp, _Alloc>::reference
1288#  else
1289void
1290#  endif
1291list<_Tp, _Alloc>::emplace_back(_Args&&... __args) {
1292  __node_pointer __node =
1293      this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::forward<_Args>(__args)...);
1294  __link_pointer __nl = __node->__as_link();
1295  __link_nodes_at_back(__nl, __nl);
1296  ++base::__sz();
1297#  if _LIBCPP_STD_VER >= 17
1298  return __node->__get_value();
1299#  endif
1300}
1301
1302template <class _Tp, class _Alloc>
1303template <class... _Args>
1304typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::emplace(const_iterator __p, _Args&&... __args) {
1305  __node_pointer __node =
1306      this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::forward<_Args>(__args)...);
1307  __link_pointer __nl = __node->__as_link();
1308  __link_nodes(__p.__ptr_, __nl, __nl);
1309  ++base::__sz();
1310  return iterator(__nl);
1311}
1312
1313template <class _Tp, class _Alloc>
1314typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::insert(const_iterator __p, value_type&& __x) {
1315  __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, std::move(__x));
1316  __link_pointer __nl   = __node->__as_link();
1317  __link_nodes(__p.__ptr_, __nl, __nl);
1318  ++base::__sz();
1319  return iterator(__nl);
1320}
1321
1322#endif // _LIBCPP_CXX03_LANG
1323
1324template <class _Tp, class _Alloc>
1325void list<_Tp, _Alloc>::pop_front() {
1326  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::pop_front() called with empty list");
1327  __link_pointer __n = base::__end_.__next_;
1328  base::__unlink_nodes(__n, __n);
1329  --base::__sz();
1330  this->__delete_node(__n->__as_node());
1331}
1332
1333template <class _Tp, class _Alloc>
1334void list<_Tp, _Alloc>::pop_back() {
1335  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "list::pop_back() called on an empty list");
1336  __link_pointer __n = base::__end_.__prev_;
1337  base::__unlink_nodes(__n, __n);
1338  --base::__sz();
1339  this->__delete_node(__n->__as_node());
1340}
1341
1342template <class _Tp, class _Alloc>
1343typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::erase(const_iterator __p) {
1344  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p != end(), "list::erase(iterator) called with a non-dereferenceable iterator");
1345  __link_pointer __n = __p.__ptr_;
1346  __link_pointer __r = __n->__next_;
1347  base::__unlink_nodes(__n, __n);
1348  --base::__sz();
1349  this->__delete_node(__n->__as_node());
1350  return iterator(__r);
1351}
1352
1353template <class _Tp, class _Alloc>
1354typename list<_Tp, _Alloc>::iterator list<_Tp, _Alloc>::erase(const_iterator __f, const_iterator __l) {
1355  if (__f != __l) {
1356    base::__unlink_nodes(__f.__ptr_, __l.__ptr_->__prev_);
1357    while (__f != __l) {
1358      __link_pointer __n = __f.__ptr_;
1359      ++__f;
1360      --base::__sz();
1361      this->__delete_node(__n->__as_node());
1362    }
1363  }
1364  return iterator(__l.__ptr_);
1365}
1366
1367template <class _Tp, class _Alloc>
1368void list<_Tp, _Alloc>::resize(size_type __n) {
1369  if (__n < base::__sz())
1370    erase(__iterator(__n), end());
1371  else if (__n > base::__sz()) {
1372    __n -= base::__sz();
1373    size_type __ds        = 0;
1374    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr);
1375    ++__ds;
1376    iterator __r = iterator(__node->__as_link());
1377    iterator __e = __r;
1378#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1379    try {
1380#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1381      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
1382        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr)->__as_link();
1383      }
1384#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1385    } catch (...) {
1386      while (true) {
1387        __link_pointer __prev    = __e.__ptr_->__prev_;
1388        __node_pointer __current = __e.__ptr_->__as_node();
1389        this->__delete_node(__current);
1390        if (__prev == 0)
1391          break;
1392        __e = iterator(__prev);
1393      }
1394      throw;
1395    }
1396#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1397    __link_nodes_at_back(__r.__ptr_, __e.__ptr_);
1398    base::__sz() += __ds;
1399  }
1400}
1401
1402template <class _Tp, class _Alloc>
1403void list<_Tp, _Alloc>::resize(size_type __n, const value_type& __x) {
1404  if (__n < base::__sz())
1405    erase(__iterator(__n), end());
1406  else if (__n > base::__sz()) {
1407    __n -= base::__sz();
1408    size_type __ds        = 0;
1409    __node_pointer __node = this->__create_node(/* prev = */ nullptr, /* next = */ nullptr, __x);
1410    ++__ds;
1411    __link_pointer __nl = __node->__as_link();
1412    iterator __r        = iterator(__nl);
1413    iterator __e        = __r;
1414#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1415    try {
1416#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1417      for (--__n; __n != 0; --__n, (void)++__e, ++__ds) {
1418        __e.__ptr_->__next_ = this->__create_node(/* prev = */ __e.__ptr_, /* next = */ nullptr, __x)->__as_link();
1419      }
1420#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1421    } catch (...) {
1422      while (true) {
1423        __link_pointer __prev    = __e.__ptr_->__prev_;
1424        __node_pointer __current = __e.__ptr_->__as_node();
1425        this->__delete_node(__current);
1426        if (__prev == 0)
1427          break;
1428        __e = iterator(__prev);
1429      }
1430      throw;
1431    }
1432#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1433    __link_nodes(base::__end_as_link(), __r.__ptr_, __e.__ptr_);
1434    base::__sz() += __ds;
1435  }
1436}
1437
1438template <class _Tp, class _Alloc>
1439void list<_Tp, _Alloc>::splice(const_iterator __p, list& __c) {
1440  _LIBCPP_ASSERT_VALID_INPUT_RANGE(
1441      this != std::addressof(__c), "list::splice(iterator, list) called with this == &list");
1442  if (!__c.empty()) {
1443    __link_pointer __f = __c.__end_.__next_;
1444    __link_pointer __l = __c.__end_.__prev_;
1445    base::__unlink_nodes(__f, __l);
1446    __link_nodes(__p.__ptr_, __f, __l);
1447    base::__sz() += __c.__sz();
1448    __c.__sz() = 0;
1449  }
1450}
1451
1452template <class _Tp, class _Alloc>
1453void list<_Tp, _Alloc>::splice(const_iterator __p, list& __c, const_iterator __i) {
1454  if (__p.__ptr_ != __i.__ptr_ && __p.__ptr_ != __i.__ptr_->__next_) {
1455    __link_pointer __f = __i.__ptr_;
1456    base::__unlink_nodes(__f, __f);
1457    __link_nodes(__p.__ptr_, __f, __f);
1458    --__c.__sz();
1459    ++base::__sz();
1460  }
1461}
1462
1463template <class _Tp, class _Alloc>
1464void list<_Tp, _Alloc>::splice(const_iterator __p, list& __c, const_iterator __f, const_iterator __l) {
1465  if (__f != __l) {
1466    __link_pointer __first = __f.__ptr_;
1467    --__l;
1468    __link_pointer __last = __l.__ptr_;
1469    if (this != std::addressof(__c)) {
1470      size_type __s = std::distance(__f, __l) + 1;
1471      __c.__sz() -= __s;
1472      base::__sz() += __s;
1473    }
1474    base::__unlink_nodes(__first, __last);
1475    __link_nodes(__p.__ptr_, __first, __last);
1476  }
1477}
1478
1479template <class _Tp, class _Alloc>
1480typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::remove(const value_type& __x) {
1481  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
1482  for (const_iterator __i = begin(), __e = end(); __i != __e;) {
1483    if (*__i == __x) {
1484      const_iterator __j = std::next(__i);
1485      for (; __j != __e && *__j == __x; ++__j)
1486        ;
1487      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
1488      __i = __j;
1489      if (__i != __e)
1490        ++__i;
1491    } else
1492      ++__i;
1493  }
1494
1495  return (__remove_return_type)__deleted_nodes.size();
1496}
1497
1498template <class _Tp, class _Alloc>
1499template <class _Pred>
1500typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::remove_if(_Pred __pred) {
1501  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
1502  for (iterator __i = begin(), __e = end(); __i != __e;) {
1503    if (__pred(*__i)) {
1504      iterator __j = std::next(__i);
1505      for (; __j != __e && __pred(*__j); ++__j)
1506        ;
1507      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
1508      __i = __j;
1509      if (__i != __e)
1510        ++__i;
1511    } else
1512      ++__i;
1513  }
1514
1515  return (__remove_return_type)__deleted_nodes.size();
1516}
1517
1518template <class _Tp, class _Alloc>
1519template <class _BinaryPred>
1520typename list<_Tp, _Alloc>::__remove_return_type list<_Tp, _Alloc>::unique(_BinaryPred __binary_pred) {
1521  list<_Tp, _Alloc> __deleted_nodes(get_allocator()); // collect the nodes we're removing
1522  for (iterator __i = begin(), __e = end(); __i != __e;) {
1523    iterator __j = std::next(__i);
1524    for (; __j != __e && __binary_pred(*__i, *__j); ++__j)
1525      ;
1526    if (++__i != __j) {
1527      __deleted_nodes.splice(__deleted_nodes.end(), *this, __i, __j);
1528      __i = __j;
1529    }
1530  }
1531
1532  return (__remove_return_type)__deleted_nodes.size();
1533}
1534
1535template <class _Tp, class _Alloc>
1536inline void list<_Tp, _Alloc>::merge(list& __c) {
1537  merge(__c, __less<>());
1538}
1539
1540template <class _Tp, class _Alloc>
1541template <class _Comp>
1542void list<_Tp, _Alloc>::merge(list& __c, _Comp __comp) {
1543  if (this != std::addressof(__c)) {
1544    iterator __f1 = begin();
1545    iterator __e1 = end();
1546    iterator __f2 = __c.begin();
1547    iterator __e2 = __c.end();
1548    while (__f1 != __e1 && __f2 != __e2) {
1549      if (__comp(*__f2, *__f1)) {
1550        size_type __ds = 1;
1551        iterator __m2  = std::next(__f2);
1552        for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2, (void)++__ds)
1553          ;
1554        base::__sz() += __ds;
1555        __c.__sz() -= __ds;
1556        __link_pointer __f = __f2.__ptr_;
1557        __link_pointer __l = __m2.__ptr_->__prev_;
1558        __f2               = __m2;
1559        base::__unlink_nodes(__f, __l);
1560        __m2 = std::next(__f1);
1561        __link_nodes(__f1.__ptr_, __f, __l);
1562        __f1 = __m2;
1563      } else
1564        ++__f1;
1565    }
1566    splice(__e1, __c);
1567  }
1568}
1569
1570template <class _Tp, class _Alloc>
1571inline void list<_Tp, _Alloc>::sort() {
1572  sort(__less<>());
1573}
1574
1575template <class _Tp, class _Alloc>
1576template <class _Comp>
1577inline void list<_Tp, _Alloc>::sort(_Comp __comp) {
1578  __sort(begin(), end(), base::__sz(), __comp);
1579}
1580
1581template <class _Tp, class _Alloc>
1582template <class _Comp>
1583typename list<_Tp, _Alloc>::iterator
1584list<_Tp, _Alloc>::__sort(iterator __f1, iterator __e2, size_type __n, _Comp& __comp) {
1585  switch (__n) {
1586  case 0:
1587  case 1:
1588    return __f1;
1589  case 2:
1590    if (__comp(*--__e2, *__f1)) {
1591      __link_pointer __f = __e2.__ptr_;
1592      base::__unlink_nodes(__f, __f);
1593      __link_nodes(__f1.__ptr_, __f, __f);
1594      return __e2;
1595    }
1596    return __f1;
1597  }
1598  size_type __n2 = __n / 2;
1599  iterator __e1  = std::next(__f1, __n2);
1600  iterator __r = __f1 = __sort(__f1, __e1, __n2, __comp);
1601  iterator __f2 = __e1 = __sort(__e1, __e2, __n - __n2, __comp);
1602  if (__comp(*__f2, *__f1)) {
1603    iterator __m2 = std::next(__f2);
1604    for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2)
1605      ;
1606    __link_pointer __f = __f2.__ptr_;
1607    __link_pointer __l = __m2.__ptr_->__prev_;
1608    __r                = __f2;
1609    __e1 = __f2 = __m2;
1610    base::__unlink_nodes(__f, __l);
1611    __m2 = std::next(__f1);
1612    __link_nodes(__f1.__ptr_, __f, __l);
1613    __f1 = __m2;
1614  } else
1615    ++__f1;
1616  while (__f1 != __e1 && __f2 != __e2) {
1617    if (__comp(*__f2, *__f1)) {
1618      iterator __m2 = std::next(__f2);
1619      for (; __m2 != __e2 && __comp(*__m2, *__f1); ++__m2)
1620        ;
1621      __link_pointer __f = __f2.__ptr_;
1622      __link_pointer __l = __m2.__ptr_->__prev_;
1623      if (__e1 == __f2)
1624        __e1 = __m2;
1625      __f2 = __m2;
1626      base::__unlink_nodes(__f, __l);
1627      __m2 = std::next(__f1);
1628      __link_nodes(__f1.__ptr_, __f, __l);
1629      __f1 = __m2;
1630    } else
1631      ++__f1;
1632  }
1633  return __r;
1634}
1635
1636template <class _Tp, class _Alloc>
1637void list<_Tp, _Alloc>::reverse() _NOEXCEPT {
1638  if (base::__sz() > 1) {
1639    iterator __e = end();
1640    for (iterator __i = begin(); __i.__ptr_ != __e.__ptr_;) {
1641      std::swap(__i.__ptr_->__prev_, __i.__ptr_->__next_);
1642      __i.__ptr_ = __i.__ptr_->__prev_;
1643    }
1644    std::swap(__e.__ptr_->__prev_, __e.__ptr_->__next_);
1645  }
1646}
1647
1648template <class _Tp, class _Alloc>
1649bool list<_Tp, _Alloc>::__invariants() const {
1650  return size() == std::distance(begin(), end());
1651}
1652
1653template <class _Tp, class _Alloc>
1654inline _LIBCPP_HIDE_FROM_ABI bool operator==(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1655  return __x.size() == __y.size() && std::equal(__x.begin(), __x.end(), __y.begin());
1656}
1657
1658#if _LIBCPP_STD_VER <= 17
1659
1660template <class _Tp, class _Alloc>
1661inline _LIBCPP_HIDE_FROM_ABI bool operator<(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1662  return std::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
1663}
1664
1665template <class _Tp, class _Alloc>
1666inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1667  return !(__x == __y);
1668}
1669
1670template <class _Tp, class _Alloc>
1671inline _LIBCPP_HIDE_FROM_ABI bool operator>(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1672  return __y < __x;
1673}
1674
1675template <class _Tp, class _Alloc>
1676inline _LIBCPP_HIDE_FROM_ABI bool operator>=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1677  return !(__x < __y);
1678}
1679
1680template <class _Tp, class _Alloc>
1681inline _LIBCPP_HIDE_FROM_ABI bool operator<=(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y) {
1682  return !(__y < __x);
1683}
1684
1685#else // _LIBCPP_STD_VER <= 17
1686
1687template <class _Tp, class _Allocator>
1688_LIBCPP_HIDE_FROM_ABI __synth_three_way_result<_Tp>
1689operator<=>(const list<_Tp, _Allocator>& __x, const list<_Tp, _Allocator>& __y) {
1690  return std::lexicographical_compare_three_way(
1691      __x.begin(), __x.end(), __y.begin(), __y.end(), std::__synth_three_way<_Tp, _Tp>);
1692}
1693
1694#endif // _LIBCPP_STD_VER <= 17
1695
1696template <class _Tp, class _Alloc>
1697inline _LIBCPP_HIDE_FROM_ABI void swap(list<_Tp, _Alloc>& __x, list<_Tp, _Alloc>& __y)
1698    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y))) {
1699  __x.swap(__y);
1700}
1701
1702#if _LIBCPP_STD_VER >= 20
1703template <class _Tp, class _Allocator, class _Predicate>
1704inline _LIBCPP_HIDE_FROM_ABI typename list<_Tp, _Allocator>::size_type
1705erase_if(list<_Tp, _Allocator>& __c, _Predicate __pred) {
1706  return __c.remove_if(__pred);
1707}
1708
1709template <class _Tp, class _Allocator, class _Up>
1710inline _LIBCPP_HIDE_FROM_ABI typename list<_Tp, _Allocator>::size_type
1711erase(list<_Tp, _Allocator>& __c, const _Up& __v) {
1712  return std::erase_if(__c, [&](auto& __elem) { return __elem == __v; });
1713}
1714
1715template <>
1716inline constexpr bool __format::__enable_insertable<std::list<char>> = true;
1717#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1718template <>
1719inline constexpr bool __format::__enable_insertable<std::list<wchar_t>> = true;
1720#  endif
1721
1722#endif // _LIBCPP_STD_VER >= 20
1723
1724_LIBCPP_END_NAMESPACE_STD
1725
1726#if _LIBCPP_STD_VER >= 17
1727_LIBCPP_BEGIN_NAMESPACE_STD
1728namespace pmr {
1729template <class _ValueT>
1730using list _LIBCPP_AVAILABILITY_PMR = std::list<_ValueT, polymorphic_allocator<_ValueT>>;
1731} // namespace pmr
1732_LIBCPP_END_NAMESPACE_STD
1733#endif
1734
1735_LIBCPP_POP_MACROS
1736
1737#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1738#  include <algorithm>
1739#  include <atomic>
1740#  include <concepts>
1741#  include <cstdint>
1742#  include <cstdlib>
1743#  include <functional>
1744#  include <iosfwd>
1745#  include <iterator>
1746#  include <stdexcept>
1747#  include <type_traits>
1748#  include <typeinfo>
1749#endif
1750
1751#endif // _LIBCPP_LIST
1752