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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_DEQUE
11#define _LIBCPP_DEQUE
12
13/*
14    deque synopsis
15
16namespace std
17{
18
19template <class T, class Allocator = allocator<T> >
20class deque
21{
22public:
23    // types:
24    typedef T value_type;
25    typedef Allocator allocator_type;
26
27    typedef typename allocator_type::reference       reference;
28    typedef typename allocator_type::const_reference const_reference;
29    typedef implementation-defined                   iterator;
30    typedef implementation-defined                   const_iterator;
31    typedef typename allocator_type::size_type       size_type;
32    typedef typename allocator_type::difference_type difference_type;
33
34    typedef typename allocator_type::pointer         pointer;
35    typedef typename allocator_type::const_pointer   const_pointer;
36    typedef std::reverse_iterator<iterator>          reverse_iterator;
37    typedef std::reverse_iterator<const_iterator>    const_reverse_iterator;
38
39    // construct/copy/destroy:
40    deque() noexcept(is_nothrow_default_constructible<allocator_type>::value);
41    explicit deque(const allocator_type& a);
42    explicit deque(size_type n);
43    explicit deque(size_type n, const allocator_type& a); // C++14
44    deque(size_type n, const value_type& v);
45    deque(size_type n, const value_type& v, const allocator_type& a);
46    template <class InputIterator>
47        deque(InputIterator f, InputIterator l);
48    template <class InputIterator>
49        deque(InputIterator f, InputIterator l, const allocator_type& a);
50    deque(const deque& c);
51    deque(deque&& c)
52        noexcept(is_nothrow_move_constructible<allocator_type>::value);
53    deque(initializer_list<value_type> il, const Allocator& a = allocator_type());
54    deque(const deque& c, const allocator_type& a);
55    deque(deque&& c, const allocator_type& a);
56    ~deque();
57
58    deque& operator=(const deque& c);
59    deque& operator=(deque&& c)
60        noexcept(
61             allocator_type::propagate_on_container_move_assignment::value &&
62             is_nothrow_move_assignable<allocator_type>::value);
63    deque& operator=(initializer_list<value_type> il);
64
65    template <class InputIterator>
66        void assign(InputIterator f, InputIterator l);
67    void assign(size_type n, const value_type& v);
68    void assign(initializer_list<value_type> il);
69
70    allocator_type get_allocator() const noexcept;
71
72    // iterators:
73
74    iterator       begin() noexcept;
75    const_iterator begin() const noexcept;
76    iterator       end() noexcept;
77    const_iterator end() const noexcept;
78
79    reverse_iterator       rbegin() noexcept;
80    const_reverse_iterator rbegin() const noexcept;
81    reverse_iterator       rend() noexcept;
82    const_reverse_iterator rend() const noexcept;
83
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    // capacity:
90    size_type size() const noexcept;
91    size_type max_size() const noexcept;
92    void resize(size_type n);
93    void resize(size_type n, const value_type& v);
94    void shrink_to_fit();
95    bool empty() const noexcept;
96
97    // element access:
98    reference operator[](size_type i);
99    const_reference operator[](size_type i) const;
100    reference at(size_type i);
101    const_reference at(size_type i) const;
102    reference front();
103    const_reference front() const;
104    reference back();
105    const_reference back() const;
106
107    // modifiers:
108    void push_front(const value_type& v);
109    void push_front(value_type&& v);
110    void push_back(const value_type& v);
111    void push_back(value_type&& v);
112    template <class... Args> reference emplace_front(Args&&... args);  // reference in C++17
113    template <class... Args> reference emplace_back(Args&&... args);   // reference in C++17
114    template <class... Args> iterator emplace(const_iterator p, Args&&... args);
115    iterator insert(const_iterator p, const value_type& v);
116    iterator insert(const_iterator p, value_type&& v);
117    iterator insert(const_iterator p, size_type n, const value_type& v);
118    template <class InputIterator>
119        iterator insert(const_iterator p, InputIterator f, InputIterator l);
120    iterator insert(const_iterator p, initializer_list<value_type> il);
121    void pop_front();
122    void pop_back();
123    iterator erase(const_iterator p);
124    iterator erase(const_iterator f, const_iterator l);
125    void swap(deque& c)
126        noexcept(allocator_traits<allocator_type>::is_always_equal::value);  // C++17
127    void clear() noexcept;
128};
129
130template <class InputIterator, class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
131   deque(InputIterator, InputIterator, Allocator = Allocator())
132   -> deque<typename iterator_traits<InputIterator>::value_type, Allocator>; // C++17
133
134template <class T, class Allocator>
135    bool operator==(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
136template <class T, class Allocator>
137    bool operator< (const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
138template <class T, class Allocator>
139    bool operator!=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
140template <class T, class Allocator>
141    bool operator> (const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
142template <class T, class Allocator>
143    bool operator>=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
144template <class T, class Allocator>
145    bool operator<=(const deque<T,Allocator>& x, const deque<T,Allocator>& y); // removed in C++20
146template<class T, class Allocator>
147    synth-three-way-result<T> operator<=>(const deque<T, Allocator>& x,
148                                          const deque<T, Allocator>& y);       // since C++20
149
150// specialized algorithms:
151template <class T, class Allocator>
152    void swap(deque<T,Allocator>& x, deque<T,Allocator>& y)
153         noexcept(noexcept(x.swap(y)));
154
155template <class T, class Allocator, class U>
156    typename deque<T, Allocator>::size_type
157    erase(deque<T, Allocator>& c, const U& value);       // C++20
158template <class T, class Allocator, class Predicate>
159    typename deque<T, Allocator>::size_type
160    erase_if(deque<T, Allocator>& c, Predicate pred);    // C++20
161
162}  // std
163
164*/
165
166#include <__algorithm/copy.h>
167#include <__algorithm/copy_backward.h>
168#include <__algorithm/equal.h>
169#include <__algorithm/fill_n.h>
170#include <__algorithm/lexicographical_compare.h>
171#include <__algorithm/lexicographical_compare_three_way.h>
172#include <__algorithm/min.h>
173#include <__algorithm/remove.h>
174#include <__algorithm/remove_if.h>
175#include <__algorithm/unwrap_iter.h>
176#include <__assert> // all public C++ headers provide the assertion handler
177#include <__config>
178#include <__format/enable_insertable.h>
179#include <__iterator/iterator_traits.h>
180#include <__iterator/next.h>
181#include <__iterator/prev.h>
182#include <__iterator/reverse_iterator.h>
183#include <__iterator/segmented_iterator.h>
184#include <__memory/addressof.h>
185#include <__memory/allocator_destructor.h>
186#include <__memory/pointer_traits.h>
187#include <__memory/temp_value.h>
188#include <__memory/unique_ptr.h>
189#include <__memory_resource/polymorphic_allocator.h>
190#include <__split_buffer>
191#include <__type_traits/is_allocator.h>
192#include <__type_traits/is_convertible.h>
193#include <__type_traits/is_same.h>
194#include <__type_traits/type_identity.h>
195#include <__utility/forward.h>
196#include <__utility/move.h>
197#include <__utility/swap.h>
198#include <limits>
199#include <stdexcept>
200#include <version>
201
202// standard-mandated includes
203
204// [iterator.range]
205#include <__iterator/access.h>
206#include <__iterator/data.h>
207#include <__iterator/empty.h>
208#include <__iterator/reverse_access.h>
209#include <__iterator/size.h>
210
211// [deque.syn]
212#include <compare>
213#include <initializer_list>
214
215#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
216#  pragma GCC system_header
217#endif
218
219_LIBCPP_PUSH_MACROS
220#include <__undef_macros>
221
222
223_LIBCPP_BEGIN_NAMESPACE_STD
224
225template <class _Tp, class _Allocator = allocator<_Tp> > class _LIBCPP_TEMPLATE_VIS deque;
226
227template <class _ValueType, class _DiffType>
228struct __deque_block_size {
229  static const _DiffType value = sizeof(_ValueType) < 256 ? 4096 / sizeof(_ValueType) : 16;
230};
231
232template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
233          class _DiffType, _DiffType _BS =
234#ifdef _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
235// Keep template parameter to avoid changing all template declarations thoughout
236// this file.
237                               0
238#else
239                               __deque_block_size<_ValueType, _DiffType>::value
240#endif
241          >
242class _LIBCPP_TEMPLATE_VIS __deque_iterator
243{
244    typedef _MapPointer __map_iterator;
245public:
246    typedef _Pointer  pointer;
247    typedef _DiffType difference_type;
248private:
249    __map_iterator __m_iter_;
250    pointer        __ptr_;
251
252    static const difference_type __block_size;
253public:
254    typedef _ValueType                  value_type;
255    typedef random_access_iterator_tag  iterator_category;
256    typedef _Reference                  reference;
257
258    _LIBCPP_HIDE_FROM_ABI __deque_iterator() _NOEXCEPT
259#if _LIBCPP_STD_VER >= 14
260     : __m_iter_(nullptr), __ptr_(nullptr)
261#endif
262     {}
263
264    template <class _Pp, class _Rp, class _MP>
265    _LIBCPP_HIDE_FROM_ABI
266    __deque_iterator(const __deque_iterator<value_type, _Pp, _Rp, _MP, difference_type, _BS>& __it,
267                typename enable_if<is_convertible<_Pp, pointer>::value>::type* = 0) _NOEXCEPT
268        : __m_iter_(__it.__m_iter_), __ptr_(__it.__ptr_) {}
269
270    _LIBCPP_HIDE_FROM_ABI reference operator*() const {return *__ptr_;}
271    _LIBCPP_HIDE_FROM_ABI pointer operator->() const {return __ptr_;}
272
273    _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator++()
274    {
275        if (++__ptr_ - *__m_iter_ == __block_size)
276        {
277            ++__m_iter_;
278            __ptr_ = *__m_iter_;
279        }
280        return *this;
281    }
282
283    _LIBCPP_HIDE_FROM_ABI __deque_iterator operator++(int)
284    {
285        __deque_iterator __tmp = *this;
286        ++(*this);
287        return __tmp;
288    }
289
290    _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator--()
291    {
292        if (__ptr_ == *__m_iter_)
293        {
294            --__m_iter_;
295            __ptr_ = *__m_iter_ + __block_size;
296        }
297        --__ptr_;
298        return *this;
299    }
300
301    _LIBCPP_HIDE_FROM_ABI __deque_iterator operator--(int)
302    {
303        __deque_iterator __tmp = *this;
304        --(*this);
305        return __tmp;
306    }
307
308    _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator+=(difference_type __n)
309    {
310        if (__n != 0)
311        {
312            __n += __ptr_ - *__m_iter_;
313            if (__n > 0)
314            {
315                __m_iter_ += __n / __block_size;
316                __ptr_ = *__m_iter_ + __n % __block_size;
317            }
318            else // (__n < 0)
319            {
320                difference_type __z = __block_size - 1 - __n;
321                __m_iter_ -= __z / __block_size;
322                __ptr_ = *__m_iter_ + (__block_size - 1 - __z % __block_size);
323            }
324        }
325        return *this;
326    }
327
328    _LIBCPP_HIDE_FROM_ABI __deque_iterator& operator-=(difference_type __n)
329    {
330        return *this += -__n;
331    }
332
333    _LIBCPP_HIDE_FROM_ABI __deque_iterator operator+(difference_type __n) const
334    {
335        __deque_iterator __t(*this);
336        __t += __n;
337        return __t;
338    }
339
340    _LIBCPP_HIDE_FROM_ABI __deque_iterator operator-(difference_type __n) const
341    {
342        __deque_iterator __t(*this);
343        __t -= __n;
344        return __t;
345    }
346
347    _LIBCPP_HIDE_FROM_ABI
348    friend __deque_iterator operator+(difference_type __n, const __deque_iterator& __it)
349        {return __it + __n;}
350
351    _LIBCPP_HIDE_FROM_ABI
352    friend difference_type operator-(const __deque_iterator& __x, const __deque_iterator& __y)
353    {
354        if (__x != __y)
355            return (__x.__m_iter_ - __y.__m_iter_) * __block_size
356                 + (__x.__ptr_ - *__x.__m_iter_)
357                 - (__y.__ptr_ - *__y.__m_iter_);
358        return 0;
359    }
360
361    _LIBCPP_HIDE_FROM_ABI reference operator[](difference_type __n) const
362        {return *(*this + __n);}
363
364    _LIBCPP_HIDE_FROM_ABI friend
365        bool operator==(const __deque_iterator& __x, const __deque_iterator& __y)
366        {return __x.__ptr_ == __y.__ptr_;}
367
368    _LIBCPP_HIDE_FROM_ABI friend
369        bool operator!=(const __deque_iterator& __x, const __deque_iterator& __y)
370        {return !(__x == __y);}
371
372    _LIBCPP_HIDE_FROM_ABI friend
373        bool operator<(const __deque_iterator& __x, const __deque_iterator& __y)
374        {return __x.__m_iter_ < __y.__m_iter_ ||
375               (__x.__m_iter_ == __y.__m_iter_ && __x.__ptr_ < __y.__ptr_);}
376
377    _LIBCPP_HIDE_FROM_ABI friend
378        bool operator>(const __deque_iterator& __x, const __deque_iterator& __y)
379        {return __y < __x;}
380
381    _LIBCPP_HIDE_FROM_ABI friend
382        bool operator<=(const __deque_iterator& __x, const __deque_iterator& __y)
383        {return !(__y < __x);}
384
385    _LIBCPP_HIDE_FROM_ABI friend
386        bool operator>=(const __deque_iterator& __x, const __deque_iterator& __y)
387        {return !(__x < __y);}
388
389private:
390    _LIBCPP_HIDE_FROM_ABI explicit __deque_iterator(__map_iterator __m, pointer __p) _NOEXCEPT
391        : __m_iter_(__m), __ptr_(__p) {}
392
393    template <class _Tp, class _Ap> friend class _LIBCPP_TEMPLATE_VIS deque;
394    template <class _Vp, class _Pp, class _Rp, class _MP, class _Dp, _Dp>
395        friend class _LIBCPP_TEMPLATE_VIS __deque_iterator;
396
397    template <class>
398    friend struct __segmented_iterator_traits;
399};
400
401template <class _ValueType, class _Pointer, class _Reference, class _MapPointer, class _DiffType, _DiffType _BlockSize>
402struct __segmented_iterator_traits<
403    __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer, _DiffType, _BlockSize> > {
404private:
405  using _Iterator = __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer, _DiffType, _BlockSize>;
406
407public:
408  using __is_segmented_iterator = true_type;
409  using __segment_iterator = _MapPointer;
410  using __local_iterator = _Pointer;
411
412  static _LIBCPP_HIDE_FROM_ABI __segment_iterator __segment(_Iterator __iter) { return __iter.__m_iter_; }
413  static _LIBCPP_HIDE_FROM_ABI __local_iterator __local(_Iterator __iter) { return __iter.__ptr_; }
414  static _LIBCPP_HIDE_FROM_ABI __local_iterator __begin(__segment_iterator __iter) { return *__iter; }
415
416  static _LIBCPP_HIDE_FROM_ABI __local_iterator __end(__segment_iterator __iter) {
417        return *__iter + _Iterator::__block_size;
418  }
419
420  static _LIBCPP_HIDE_FROM_ABI _Iterator __compose(__segment_iterator __segment, __local_iterator __local) {
421        if (__local == __end(__segment)) {
422            ++__segment;
423            return _Iterator(__segment, *__segment);
424        }
425        return _Iterator(__segment, __local);
426  }
427};
428
429template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
430          class _DiffType, _DiffType _BlockSize>
431const _DiffType __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer,
432                                 _DiffType, _BlockSize>::__block_size =
433    __deque_block_size<_ValueType, _DiffType>::value;
434
435template <class _Tp, class _Allocator /*= allocator<_Tp>*/>
436class _LIBCPP_TEMPLATE_VIS deque
437{
438public:
439    // types:
440
441  using value_type = _Tp;
442
443  static_assert((is_same<typename _Allocator::value_type, value_type>::value),
444                "Allocator::value_type must be same type as value_type");
445
446  using allocator_type = _Allocator;
447  using __alloc_traits = allocator_traits<allocator_type>;
448
449  using size_type       = typename __alloc_traits::size_type;
450  using difference_type = typename __alloc_traits::difference_type;
451
452  using pointer       = typename __alloc_traits::pointer;
453  using const_pointer = typename __alloc_traits::const_pointer;
454
455  using __pointer_allocator       = __rebind_alloc<__alloc_traits, pointer>;
456  using __const_pointer_allocator = __rebind_alloc<__alloc_traits, const_pointer>;
457  using __map                     = __split_buffer<pointer, __pointer_allocator>;
458  using __map_alloc_traits        = allocator_traits<__pointer_allocator>;
459  using __map_pointer             = typename __map_alloc_traits::pointer;
460  using __map_const_pointer       = typename allocator_traits<__const_pointer_allocator>::const_pointer;
461
462  using reference       = value_type&;
463  using const_reference = const value_type&;
464
465  using iterator = __deque_iterator<value_type, pointer, reference, __map_pointer, difference_type>;
466  using const_iterator =
467      __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer, difference_type>;
468  using reverse_iterator       = std::reverse_iterator<iterator>;
469  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
470
471  static_assert(is_same<allocator_type, __rebind_alloc<__alloc_traits, value_type> >::value,
472                "[allocator.requirements] states that rebinding an allocator to the same type should result in the "
473                "original allocator");
474  static_assert(is_nothrow_default_constructible<allocator_type>::value ==
475                    is_nothrow_default_constructible<__pointer_allocator>::value,
476                "rebinding an allocator should not change excpetion guarantees");
477  static_assert(is_nothrow_move_constructible<allocator_type>::value ==
478                    is_nothrow_move_constructible<typename __map::allocator_type>::value,
479                "rebinding an allocator should not change excpetion guarantees");
480
481private:
482  struct __deque_block_range {
483    explicit _LIBCPP_HIDE_FROM_ABI
484    __deque_block_range(pointer __b, pointer __e) _NOEXCEPT : __begin_(__b), __end_(__e) {}
485    const pointer __begin_;
486    const pointer __end_;
487  };
488
489  struct __deque_range {
490    iterator __pos_;
491    const iterator __end_;
492
493    _LIBCPP_HIDE_FROM_ABI __deque_range(iterator __pos, iterator __e) _NOEXCEPT
494      : __pos_(__pos), __end_(__e) {}
495
496    explicit _LIBCPP_HIDE_FROM_ABI operator bool() const _NOEXCEPT {
497      return __pos_ != __end_;
498    }
499
500    _LIBCPP_HIDE_FROM_ABI __deque_range begin() const {
501      return *this;
502    }
503
504    _LIBCPP_HIDE_FROM_ABI __deque_range end() const {
505      return __deque_range(__end_, __end_);
506    }
507    _LIBCPP_HIDE_FROM_ABI __deque_block_range operator*() const _NOEXCEPT {
508        if (__pos_.__m_iter_ == __end_.__m_iter_) {
509        return __deque_block_range(__pos_.__ptr_, __end_.__ptr_);
510      }
511      return __deque_block_range(__pos_.__ptr_, *__pos_.__m_iter_ + __block_size);
512    }
513
514    _LIBCPP_HIDE_FROM_ABI __deque_range& operator++() _NOEXCEPT {
515      if (__pos_.__m_iter_ == __end_.__m_iter_) {
516        __pos_ = __end_;
517      } else {
518        ++__pos_.__m_iter_;
519        __pos_.__ptr_ = *__pos_.__m_iter_;
520      }
521      return *this;
522    }
523
524
525    _LIBCPP_HIDE_FROM_ABI friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) {
526      return __lhs.__pos_ == __rhs.__pos_;
527    }
528    _LIBCPP_HIDE_FROM_ABI friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) {
529      return !(__lhs == __rhs);
530    }
531  };
532
533  struct _ConstructTransaction {
534    _LIBCPP_HIDE_FROM_ABI _ConstructTransaction(deque* __db, __deque_block_range& __r)
535      : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {}
536
537
538    _LIBCPP_HIDE_FROM_ABI ~_ConstructTransaction() {
539      __base_->__size() += (__pos_ - __begin_);
540    }
541
542    pointer __pos_;
543    const pointer __end_;
544  private:
545    const pointer __begin_;
546    deque* const __base_;
547  };
548
549  static const difference_type __block_size;
550
551  __map __map_;
552  size_type __start_;
553  __compressed_pair<size_type, allocator_type> __size_;
554
555public:
556
557    // construct/copy/destroy:
558    _LIBCPP_HIDE_FROM_ABI
559    deque() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
560        : __start_(0), __size_(0, __default_init_tag()) {}
561
562    _LIBCPP_HIDE_FROM_ABI ~deque() {
563      clear();
564      typename __map::iterator __i = __map_.begin();
565      typename __map::iterator __e = __map_.end();
566      for (; __i != __e; ++__i)
567          __alloc_traits::deallocate(__alloc(), *__i, __block_size);
568    }
569
570    _LIBCPP_HIDE_FROM_ABI explicit deque(const allocator_type& __a)
571        : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {}
572
573    explicit _LIBCPP_HIDE_FROM_ABI deque(size_type __n);
574#if _LIBCPP_STD_VER >= 14
575    explicit _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const _Allocator& __a);
576#endif
577    _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const value_type& __v);
578
579    template <class = __enable_if_t<__is_allocator<_Allocator>::value> >
580    _LIBCPP_HIDE_FROM_ABI deque(size_type __n, const value_type& __v, const allocator_type& __a)
581        : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a)
582    {
583        if (__n > 0)
584            __append(__n, __v);
585    }
586
587    template <class _InputIter>
588    _LIBCPP_HIDE_FROM_ABI deque(_InputIter __f, _InputIter __l,
589              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0);
590    template <class _InputIter>
591    _LIBCPP_HIDE_FROM_ABI deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
592              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0);
593    _LIBCPP_HIDE_FROM_ABI deque(const deque& __c);
594    _LIBCPP_HIDE_FROM_ABI deque(const deque& __c, const __type_identity_t<allocator_type>& __a);
595
596    _LIBCPP_HIDE_FROM_ABI deque& operator=(const deque& __c);
597
598#ifndef _LIBCPP_CXX03_LANG
599    _LIBCPP_HIDE_FROM_ABI deque(initializer_list<value_type> __il);
600    _LIBCPP_HIDE_FROM_ABI deque(initializer_list<value_type> __il, const allocator_type& __a);
601
602    _LIBCPP_HIDE_FROM_ABI
603    deque& operator=(initializer_list<value_type> __il) {assign(__il); return *this;}
604
605    _LIBCPP_HIDE_FROM_ABI
606    deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
607    _LIBCPP_HIDE_FROM_ABI
608    deque(deque&& __c, const __type_identity_t<allocator_type>& __a);
609    _LIBCPP_HIDE_FROM_ABI
610    deque& operator=(deque&& __c)
611        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
612                   is_nothrow_move_assignable<allocator_type>::value);
613
614    _LIBCPP_HIDE_FROM_ABI
615    void assign(initializer_list<value_type> __il) {assign(__il.begin(), __il.end());}
616#endif // _LIBCPP_CXX03_LANG
617
618    template <class _InputIter>
619    _LIBCPP_HIDE_FROM_ABI void assign(_InputIter __f, _InputIter __l,
620                    typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
621                                      !__is_cpp17_random_access_iterator<_InputIter>::value>::type* = 0);
622    template <class _RAIter>
623    _LIBCPP_HIDE_FROM_ABI void assign(_RAIter __f, _RAIter __l,
624                    typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
625    _LIBCPP_HIDE_FROM_ABI void assign(size_type __n, const value_type& __v);
626
627    _LIBCPP_HIDE_FROM_ABI
628    allocator_type get_allocator() const _NOEXCEPT;
629  _LIBCPP_HIDE_FROM_ABI allocator_type& __alloc() _NOEXCEPT { return __size_.second(); }
630  _LIBCPP_HIDE_FROM_ABI const allocator_type& __alloc() const _NOEXCEPT { return __size_.second(); }
631
632  // iterators:
633
634  _LIBCPP_HIDE_FROM_ABI iterator begin() _NOEXCEPT {
635      __map_pointer __mp = __map_.begin() + __start_ / __block_size;
636      return iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
637  }
638
639  _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT {
640      __map_const_pointer __mp =
641          static_cast<__map_const_pointer>(__map_.begin() + __start_ / __block_size);
642      return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
643  }
644
645  _LIBCPP_HIDE_FROM_ABI iterator end() _NOEXCEPT {
646      size_type __p      = size() + __start_;
647      __map_pointer __mp = __map_.begin() + __p / __block_size;
648      return iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
649  }
650
651  _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT {
652      size_type __p            = size() + __start_;
653      __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __p / __block_size);
654      return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
655  }
656
657    _LIBCPP_HIDE_FROM_ABI
658    reverse_iterator       rbegin() _NOEXCEPT
659        {return       reverse_iterator(end());}
660    _LIBCPP_HIDE_FROM_ABI
661    const_reverse_iterator rbegin() const _NOEXCEPT
662        {return const_reverse_iterator(end());}
663    _LIBCPP_HIDE_FROM_ABI
664    reverse_iterator       rend() _NOEXCEPT
665        {return       reverse_iterator(begin());}
666    _LIBCPP_HIDE_FROM_ABI
667    const_reverse_iterator rend()   const _NOEXCEPT
668        {return const_reverse_iterator(begin());}
669
670    _LIBCPP_HIDE_FROM_ABI
671    const_iterator         cbegin()  const _NOEXCEPT
672        {return begin();}
673    _LIBCPP_HIDE_FROM_ABI
674    const_iterator         cend()    const _NOEXCEPT
675        {return end();}
676    _LIBCPP_HIDE_FROM_ABI
677    const_reverse_iterator crbegin() const _NOEXCEPT
678        {return const_reverse_iterator(end());}
679    _LIBCPP_HIDE_FROM_ABI
680    const_reverse_iterator crend()   const _NOEXCEPT
681        {return const_reverse_iterator(begin());}
682
683    // capacity:
684    _LIBCPP_HIDE_FROM_ABI
685    size_type size() const _NOEXCEPT {return __size();}
686
687  _LIBCPP_HIDE_FROM_ABI size_type& __size() _NOEXCEPT { return __size_.first(); }
688  _LIBCPP_HIDE_FROM_ABI const size_type& __size() const _NOEXCEPT { return __size_.first(); }
689
690    _LIBCPP_HIDE_FROM_ABI
691    size_type max_size() const _NOEXCEPT
692        {return _VSTD::min<size_type>(
693            __alloc_traits::max_size(__alloc()),
694            numeric_limits<difference_type>::max());}
695    _LIBCPP_HIDE_FROM_ABI void resize(size_type __n);
696    _LIBCPP_HIDE_FROM_ABI void resize(size_type __n, const value_type& __v);
697    _LIBCPP_HIDE_FROM_ABI void shrink_to_fit() _NOEXCEPT;
698    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI
699    bool empty() const _NOEXCEPT {return size() == 0;}
700
701    // element access:
702    _LIBCPP_HIDE_FROM_ABI
703    reference operator[](size_type __i) _NOEXCEPT;
704    _LIBCPP_HIDE_FROM_ABI
705    const_reference operator[](size_type __i) const _NOEXCEPT;
706    _LIBCPP_HIDE_FROM_ABI
707    reference at(size_type __i);
708    _LIBCPP_HIDE_FROM_ABI
709    const_reference at(size_type __i) const;
710    _LIBCPP_HIDE_FROM_ABI
711    reference front() _NOEXCEPT;
712    _LIBCPP_HIDE_FROM_ABI
713    const_reference front() const _NOEXCEPT;
714    _LIBCPP_HIDE_FROM_ABI
715    reference back() _NOEXCEPT;
716    _LIBCPP_HIDE_FROM_ABI
717    const_reference back() const _NOEXCEPT;
718
719    // 23.2.2.3 modifiers:
720    _LIBCPP_HIDE_FROM_ABI void push_front(const value_type& __v);
721    _LIBCPP_HIDE_FROM_ABI void push_back(const value_type& __v);
722#ifndef _LIBCPP_CXX03_LANG
723#if _LIBCPP_STD_VER >= 17
724    template <class... _Args> _LIBCPP_HIDE_FROM_ABI reference emplace_front(_Args&&... __args);
725    template <class... _Args> _LIBCPP_HIDE_FROM_ABI reference emplace_back (_Args&&... __args);
726#else
727    template <class... _Args> _LIBCPP_HIDE_FROM_ABI void      emplace_front(_Args&&... __args);
728    template <class... _Args> _LIBCPP_HIDE_FROM_ABI void      emplace_back (_Args&&... __args);
729#endif
730    template <class... _Args> _LIBCPP_HIDE_FROM_ABI iterator emplace(const_iterator __p, _Args&&... __args);
731
732    _LIBCPP_HIDE_FROM_ABI void push_front(value_type&& __v);
733    _LIBCPP_HIDE_FROM_ABI void push_back(value_type&& __v);
734    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, value_type&& __v);
735
736    _LIBCPP_HIDE_FROM_ABI
737    iterator insert(const_iterator __p, initializer_list<value_type> __il)
738        {return insert(__p, __il.begin(), __il.end());}
739#endif // _LIBCPP_CXX03_LANG
740    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, const value_type& __v);
741    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, size_type __n, const value_type& __v);
742    template <class _InputIter>
743    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _InputIter __f, _InputIter __l,
744                         typename enable_if<__is_exactly_cpp17_input_iterator<_InputIter>::value>::type* = 0);
745    template <class _ForwardIterator>
746    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
747                        typename enable_if<__is_exactly_cpp17_forward_iterator<_ForwardIterator>::value>::type* = 0);
748    template <class _BiIter>
749    _LIBCPP_HIDE_FROM_ABI iterator insert(const_iterator __p, _BiIter __f, _BiIter __l,
750                         typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type* = 0);
751
752    _LIBCPP_HIDE_FROM_ABI void pop_front();
753    _LIBCPP_HIDE_FROM_ABI void pop_back();
754    _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __p);
755    _LIBCPP_HIDE_FROM_ABI iterator erase(const_iterator __f, const_iterator __l);
756
757    _LIBCPP_HIDE_FROM_ABI
758    void swap(deque& __c)
759#if _LIBCPP_STD_VER >= 14
760        _NOEXCEPT;
761#else
762        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
763                   __is_nothrow_swappable<allocator_type>::value);
764#endif
765    _LIBCPP_HIDE_FROM_ABI
766    void clear() _NOEXCEPT;
767
768    _LIBCPP_HIDE_FROM_ABI
769    bool __invariants() const {
770        if (!__map_.__invariants())
771            return false;
772        if (__map_.size() >= size_type(-1) / __block_size)
773            return false;
774        for (typename __map::const_iterator __i = __map_.begin(), __e = __map_.end();
775            __i != __e; ++__i)
776            if (*__i == nullptr)
777                return false;
778        if (__map_.size() != 0)
779        {
780            if (size() >= __map_.size() * __block_size)
781                return false;
782            if (__start_ >= __map_.size() * __block_size - size())
783                return false;
784        }
785        else
786        {
787            if (size() != 0)
788                return false;
789            if (__start_ != 0)
790                return false;
791        }
792        return true;
793    }
794
795    _LIBCPP_HIDE_FROM_ABI
796    void __move_assign_alloc(deque& __c)
797        _NOEXCEPT_(!__alloc_traits::propagate_on_container_move_assignment::value ||
798                   is_nothrow_move_assignable<allocator_type>::value)
799        {__move_assign_alloc(__c, integral_constant<bool,
800                      __alloc_traits::propagate_on_container_move_assignment::value>());}
801
802    _LIBCPP_HIDE_FROM_ABI
803    void __move_assign_alloc(deque& __c, true_type)
804        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
805        {
806            __alloc() = _VSTD::move(__c.__alloc());
807        }
808
809    _LIBCPP_HIDE_FROM_ABI
810    void __move_assign_alloc(deque&, false_type) _NOEXCEPT
811        {}
812
813    _LIBCPP_HIDE_FROM_ABI
814    void __move_assign(deque& __c)
815        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
816                   is_nothrow_move_assignable<allocator_type>::value)
817    {
818        __map_ = _VSTD::move(__c.__map_);
819        __start_ = __c.__start_;
820        __size() = __c.size();
821        __move_assign_alloc(__c);
822        __c.__start_ = __c.__size() = 0;
823    }
824
825    _LIBCPP_HIDE_FROM_ABI
826    static size_type __recommend_blocks(size_type __n)
827    {
828        return __n / __block_size + (__n % __block_size != 0);
829    }
830    _LIBCPP_HIDE_FROM_ABI
831    size_type __capacity() const
832    {
833        return __map_.size() == 0 ? 0 : __map_.size() * __block_size - 1;
834    }
835    _LIBCPP_HIDE_FROM_ABI
836    size_type __block_count() const
837    {
838        return __map_.size();
839    }
840
841    _LIBCPP_HIDE_FROM_ABI
842    size_type __front_spare() const
843    {
844        return __start_;
845    }
846    _LIBCPP_HIDE_FROM_ABI
847    size_type __front_spare_blocks() const {
848      return __front_spare() / __block_size;
849    }
850    _LIBCPP_HIDE_FROM_ABI
851    size_type __back_spare() const
852    {
853        return __capacity() - (__start_ + size());
854    }
855    _LIBCPP_HIDE_FROM_ABI
856    size_type __back_spare_blocks() const {
857      return __back_spare() / __block_size;
858    }
859
860 private:
861    _LIBCPP_HIDE_FROM_ABI
862    bool __maybe_remove_front_spare(bool __keep_one = true) {
863      if (__front_spare_blocks() >= 2 || (!__keep_one && __front_spare_blocks())) {
864        __alloc_traits::deallocate(__alloc(), __map_.front(),
865                                   __block_size);
866        __map_.pop_front();
867        __start_ -= __block_size;
868        return true;
869      }
870      return false;
871    }
872
873    _LIBCPP_HIDE_FROM_ABI
874    bool __maybe_remove_back_spare(bool __keep_one = true) {
875      if (__back_spare_blocks() >= 2 || (!__keep_one && __back_spare_blocks())) {
876        __alloc_traits::deallocate(__alloc(), __map_.back(),
877                                   __block_size);
878        __map_.pop_back();
879        return true;
880      }
881      return false;
882    }
883
884    template <class _InpIter>
885    _LIBCPP_HIDE_FROM_ABI void __append(_InpIter __f, _InpIter __l,
886                 typename enable_if<__is_exactly_cpp17_input_iterator<_InpIter>::value>::type* = 0);
887    template <class _ForIter>
888    _LIBCPP_HIDE_FROM_ABI void __append(_ForIter __f, _ForIter __l,
889                      typename enable_if<__is_cpp17_forward_iterator<_ForIter>::value>::type* = 0);
890    _LIBCPP_HIDE_FROM_ABI void __append(size_type __n);
891    _LIBCPP_HIDE_FROM_ABI void __append(size_type __n, const value_type& __v);
892    _LIBCPP_HIDE_FROM_ABI void __erase_to_end(const_iterator __f);
893    _LIBCPP_HIDE_FROM_ABI void __add_front_capacity();
894    _LIBCPP_HIDE_FROM_ABI void __add_front_capacity(size_type __n);
895    _LIBCPP_HIDE_FROM_ABI void __add_back_capacity();
896    _LIBCPP_HIDE_FROM_ABI void __add_back_capacity(size_type __n);
897    _LIBCPP_HIDE_FROM_ABI iterator __move_and_check(iterator __f, iterator __l, iterator __r,
898                              const_pointer& __vt);
899    _LIBCPP_HIDE_FROM_ABI iterator __move_backward_and_check(iterator __f, iterator __l, iterator __r,
900                                       const_pointer& __vt);
901    _LIBCPP_HIDE_FROM_ABI void __move_construct_and_check(iterator __f, iterator __l,
902                                    iterator __r, const_pointer& __vt);
903    _LIBCPP_HIDE_FROM_ABI void __move_construct_backward_and_check(iterator __f, iterator __l,
904                                             iterator __r, const_pointer& __vt);
905
906    _LIBCPP_HIDE_FROM_ABI
907    void __copy_assign_alloc(const deque& __c)
908        {__copy_assign_alloc(__c, integral_constant<bool,
909                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
910
911    _LIBCPP_HIDE_FROM_ABI
912    void __copy_assign_alloc(const deque& __c, true_type)
913        {
914            if (__alloc() != __c.__alloc())
915            {
916                clear();
917                shrink_to_fit();
918            }
919            __alloc() = __c.__alloc();
920            __map_.__alloc() = __c.__map_.__alloc();
921        }
922
923    _LIBCPP_HIDE_FROM_ABI
924    void __copy_assign_alloc(const deque&, false_type)
925        {}
926
927    _LIBCPP_HIDE_FROM_ABI void __move_assign(deque& __c, true_type)
928        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
929    _LIBCPP_HIDE_FROM_ABI void __move_assign(deque& __c, false_type);
930};
931
932template <class _Tp, class _Alloc>
933_LIBCPP_CONSTEXPR const typename allocator_traits<_Alloc>::difference_type deque<_Tp, _Alloc>::__block_size =
934    __deque_block_size<value_type, difference_type>::value;
935
936#if _LIBCPP_STD_VER >= 17
937template<class _InputIterator,
938         class _Alloc = allocator<__iter_value_type<_InputIterator>>,
939         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
940         class = enable_if_t<__is_allocator<_Alloc>::value>
941         >
942deque(_InputIterator, _InputIterator)
943  -> deque<__iter_value_type<_InputIterator>, _Alloc>;
944
945template<class _InputIterator,
946         class _Alloc,
947         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
948         class = enable_if_t<__is_allocator<_Alloc>::value>
949         >
950deque(_InputIterator, _InputIterator, _Alloc)
951  -> deque<__iter_value_type<_InputIterator>, _Alloc>;
952#endif
953
954template <class _Tp, class _Allocator>
955deque<_Tp, _Allocator>::deque(size_type __n)
956    : __start_(0), __size_(0, __default_init_tag())
957{
958    if (__n > 0)
959        __append(__n);
960}
961
962#if _LIBCPP_STD_VER >= 14
963template <class _Tp, class _Allocator>
964deque<_Tp, _Allocator>::deque(size_type __n, const _Allocator& __a)
965    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a)
966{
967    if (__n > 0)
968        __append(__n);
969}
970#endif
971
972template <class _Tp, class _Allocator>
973deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v)
974    : __start_(0), __size_(0, __default_init_tag())
975{
976    if (__n > 0)
977        __append(__n, __v);
978}
979
980template <class _Tp, class _Allocator>
981template <class _InputIter>
982deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l,
983              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type*)
984    : __start_(0), __size_(0, __default_init_tag())
985{
986    __append(__f, __l);
987}
988
989template <class _Tp, class _Allocator>
990template <class _InputIter>
991deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
992              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type*)
993    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a)
994{
995    __append(__f, __l);
996}
997
998template <class _Tp, class _Allocator>
999deque<_Tp, _Allocator>::deque(const deque& __c)
1000    : __map_(__pointer_allocator(__alloc_traits::select_on_container_copy_construction(__c.__alloc()))),
1001      __start_(0),
1002      __size_(0, __map_.__alloc())
1003{
1004    __append(__c.begin(), __c.end());
1005}
1006
1007template <class _Tp, class _Allocator>
1008deque<_Tp, _Allocator>::deque(const deque& __c, const __type_identity_t<allocator_type>& __a)
1009    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a)
1010{
1011    __append(__c.begin(), __c.end());
1012}
1013
1014template <class _Tp, class _Allocator>
1015deque<_Tp, _Allocator>&
1016deque<_Tp, _Allocator>::operator=(const deque& __c)
1017{
1018    if (this != _VSTD::addressof(__c))
1019    {
1020        __copy_assign_alloc(__c);
1021        assign(__c.begin(), __c.end());
1022    }
1023    return *this;
1024}
1025
1026#ifndef _LIBCPP_CXX03_LANG
1027
1028template <class _Tp, class _Allocator>
1029deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il)
1030    : __start_(0), __size_(0, __default_init_tag())
1031{
1032    __append(__il.begin(), __il.end());
1033}
1034
1035template <class _Tp, class _Allocator>
1036deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il, const allocator_type& __a)
1037    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a)
1038{
1039    __append(__il.begin(), __il.end());
1040}
1041
1042template <class _Tp, class _Allocator>
1043inline
1044deque<_Tp, _Allocator>::deque(deque&& __c)
1045    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1046    : __map_(std::move(__c.__map_)), __start_(std::move(__c.__start_)), __size_(std::move(__c.__size_))
1047{
1048  __c.__start_ = 0;
1049  __c.__size() = 0;
1050}
1051
1052template <class _Tp, class _Allocator>
1053inline
1054deque<_Tp, _Allocator>::deque(deque&& __c, const __type_identity_t<allocator_type>& __a)
1055    : __map_(std::move(__c.__map_), __pointer_allocator(__a)),
1056      __start_(std::move(__c.__start_)),
1057      __size_(std::move(__c.__size()), __a)
1058{
1059    if (__a == __c.__alloc())
1060    {
1061        __c.__start_ = 0;
1062        __c.__size() = 0;
1063    }
1064    else
1065    {
1066        __map_.clear();
1067        __start_ = 0;
1068        __size() = 0;
1069        typedef move_iterator<iterator> _Ip;
1070        assign(_Ip(__c.begin()), _Ip(__c.end()));
1071    }
1072}
1073
1074template <class _Tp, class _Allocator>
1075inline
1076deque<_Tp, _Allocator>&
1077deque<_Tp, _Allocator>::operator=(deque&& __c)
1078        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
1079                   is_nothrow_move_assignable<allocator_type>::value)
1080{
1081    __move_assign(__c, integral_constant<bool,
1082          __alloc_traits::propagate_on_container_move_assignment::value>());
1083    return *this;
1084}
1085
1086template <class _Tp, class _Allocator>
1087void
1088deque<_Tp, _Allocator>::__move_assign(deque& __c, false_type)
1089{
1090    if (__alloc() != __c.__alloc())
1091    {
1092        typedef move_iterator<iterator> _Ip;
1093        assign(_Ip(__c.begin()), _Ip(__c.end()));
1094    }
1095    else
1096        __move_assign(__c, true_type());
1097}
1098
1099template <class _Tp, class _Allocator>
1100void
1101deque<_Tp, _Allocator>::__move_assign(deque& __c, true_type)
1102    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1103{
1104    clear();
1105    shrink_to_fit();
1106    __move_assign(__c);
1107}
1108
1109#endif // _LIBCPP_CXX03_LANG
1110
1111template <class _Tp, class _Allocator>
1112template <class _InputIter>
1113void
1114deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l,
1115                               typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
1116                                                 !__is_cpp17_random_access_iterator<_InputIter>::value>::type*)
1117{
1118    iterator __i = begin();
1119    iterator __e = end();
1120    for (; __f != __l && __i != __e; ++__f, (void) ++__i)
1121        *__i = *__f;
1122    if (__f != __l)
1123        __append(__f, __l);
1124    else
1125        __erase_to_end(__i);
1126}
1127
1128template <class _Tp, class _Allocator>
1129template <class _RAIter>
1130void
1131deque<_Tp, _Allocator>::assign(_RAIter __f, _RAIter __l,
1132                               typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
1133{
1134    if (static_cast<size_type>(__l - __f) > size())
1135    {
1136        _RAIter __m = __f + size();
1137        _VSTD::copy(__f, __m, begin());
1138        __append(__m, __l);
1139    }
1140    else
1141        __erase_to_end(_VSTD::copy(__f, __l, begin()));
1142}
1143
1144template <class _Tp, class _Allocator>
1145void
1146deque<_Tp, _Allocator>::assign(size_type __n, const value_type& __v)
1147{
1148    if (__n > size())
1149    {
1150        _VSTD::fill_n(begin(), size(), __v);
1151        __n -= size();
1152        __append(__n, __v);
1153    }
1154    else
1155        __erase_to_end(_VSTD::fill_n(begin(), __n, __v));
1156}
1157
1158template <class _Tp, class _Allocator>
1159inline
1160_Allocator
1161deque<_Tp, _Allocator>::get_allocator() const _NOEXCEPT
1162{
1163    return __alloc();
1164}
1165
1166template <class _Tp, class _Allocator>
1167void
1168deque<_Tp, _Allocator>::resize(size_type __n)
1169{
1170    if (__n > size())
1171        __append(__n - size());
1172    else if (__n < size())
1173        __erase_to_end(begin() + __n);
1174}
1175
1176template <class _Tp, class _Allocator>
1177void
1178deque<_Tp, _Allocator>::resize(size_type __n, const value_type& __v)
1179{
1180    if (__n > size())
1181        __append(__n - size(), __v);
1182    else if (__n < size())
1183        __erase_to_end(begin() + __n);
1184}
1185
1186template <class _Tp, class _Allocator>
1187void
1188deque<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
1189{
1190    allocator_type& __a = __alloc();
1191    if (empty())
1192    {
1193        while (__map_.size() > 0)
1194        {
1195            __alloc_traits::deallocate(__a, __map_.back(), __block_size);
1196            __map_.pop_back();
1197        }
1198        __start_ = 0;
1199    }
1200    else
1201    {
1202      __maybe_remove_front_spare(/*__keep_one=*/false);
1203      __maybe_remove_back_spare(/*__keep_one=*/false);
1204    }
1205    __map_.shrink_to_fit();
1206}
1207
1208template <class _Tp, class _Allocator>
1209inline
1210typename deque<_Tp, _Allocator>::reference
1211deque<_Tp, _Allocator>::operator[](size_type __i) _NOEXCEPT
1212{
1213    size_type __p = __start_ + __i;
1214    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1215}
1216
1217template <class _Tp, class _Allocator>
1218inline
1219typename deque<_Tp, _Allocator>::const_reference
1220deque<_Tp, _Allocator>::operator[](size_type __i) const _NOEXCEPT
1221{
1222    size_type __p = __start_ + __i;
1223    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1224}
1225
1226template <class _Tp, class _Allocator>
1227inline
1228typename deque<_Tp, _Allocator>::reference
1229deque<_Tp, _Allocator>::at(size_type __i)
1230{
1231    if (__i >= size())
1232        _VSTD::__throw_out_of_range("deque");
1233    size_type __p = __start_ + __i;
1234    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1235}
1236
1237template <class _Tp, class _Allocator>
1238inline
1239typename deque<_Tp, _Allocator>::const_reference
1240deque<_Tp, _Allocator>::at(size_type __i) const
1241{
1242    if (__i >= size())
1243        _VSTD::__throw_out_of_range("deque");
1244    size_type __p = __start_ + __i;
1245    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1246}
1247
1248template <class _Tp, class _Allocator>
1249inline
1250typename deque<_Tp, _Allocator>::reference
1251deque<_Tp, _Allocator>::front() _NOEXCEPT
1252{
1253    return *(*(__map_.begin() + __start_ / __block_size)
1254                                    + __start_ % __block_size);
1255}
1256
1257template <class _Tp, class _Allocator>
1258inline
1259typename deque<_Tp, _Allocator>::const_reference
1260deque<_Tp, _Allocator>::front() const _NOEXCEPT
1261{
1262    return *(*(__map_.begin() + __start_ / __block_size)
1263                                      + __start_ % __block_size);
1264}
1265
1266template <class _Tp, class _Allocator>
1267inline
1268typename deque<_Tp, _Allocator>::reference
1269deque<_Tp, _Allocator>::back() _NOEXCEPT
1270{
1271    size_type __p = size() + __start_ - 1;
1272    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1273}
1274
1275template <class _Tp, class _Allocator>
1276inline
1277typename deque<_Tp, _Allocator>::const_reference
1278deque<_Tp, _Allocator>::back() const _NOEXCEPT
1279{
1280    size_type __p = size() + __start_ - 1;
1281    return *(*(__map_.begin() + __p / __block_size) + __p % __block_size);
1282}
1283
1284template <class _Tp, class _Allocator>
1285void
1286deque<_Tp, _Allocator>::push_back(const value_type& __v)
1287{
1288    allocator_type& __a = __alloc();
1289    if (__back_spare() == 0)
1290        __add_back_capacity();
1291    // __back_spare() >= 1
1292    __alloc_traits::construct(__a, _VSTD::addressof(*end()), __v);
1293    ++__size();
1294}
1295
1296template <class _Tp, class _Allocator>
1297void
1298deque<_Tp, _Allocator>::push_front(const value_type& __v)
1299{
1300    allocator_type& __a = __alloc();
1301    if (__front_spare() == 0)
1302        __add_front_capacity();
1303    // __front_spare() >= 1
1304    __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), __v);
1305    --__start_;
1306    ++__size();
1307}
1308
1309#ifndef _LIBCPP_CXX03_LANG
1310template <class _Tp, class _Allocator>
1311void
1312deque<_Tp, _Allocator>::push_back(value_type&& __v)
1313{
1314    allocator_type& __a = __alloc();
1315    if (__back_spare() == 0)
1316        __add_back_capacity();
1317    // __back_spare() >= 1
1318    __alloc_traits::construct(__a, _VSTD::addressof(*end()), _VSTD::move(__v));
1319    ++__size();
1320}
1321
1322template <class _Tp, class _Allocator>
1323template <class... _Args>
1324#if _LIBCPP_STD_VER >= 17
1325typename deque<_Tp, _Allocator>::reference
1326#else
1327void
1328#endif
1329deque<_Tp, _Allocator>::emplace_back(_Args&&... __args)
1330{
1331    allocator_type& __a = __alloc();
1332    if (__back_spare() == 0)
1333        __add_back_capacity();
1334    // __back_spare() >= 1
1335    __alloc_traits::construct(__a, _VSTD::addressof(*end()),
1336                              _VSTD::forward<_Args>(__args)...);
1337    ++__size();
1338#if _LIBCPP_STD_VER >= 17
1339    return *--end();
1340#endif
1341}
1342
1343template <class _Tp, class _Allocator>
1344void
1345deque<_Tp, _Allocator>::push_front(value_type&& __v)
1346{
1347    allocator_type& __a = __alloc();
1348    if (__front_spare() == 0)
1349        __add_front_capacity();
1350    // __front_spare() >= 1
1351    __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), _VSTD::move(__v));
1352    --__start_;
1353    ++__size();
1354}
1355
1356
1357template <class _Tp, class _Allocator>
1358template <class... _Args>
1359#if _LIBCPP_STD_VER >= 17
1360typename deque<_Tp, _Allocator>::reference
1361#else
1362void
1363#endif
1364deque<_Tp, _Allocator>::emplace_front(_Args&&... __args)
1365{
1366    allocator_type& __a = __alloc();
1367    if (__front_spare() == 0)
1368        __add_front_capacity();
1369    // __front_spare() >= 1
1370    __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), _VSTD::forward<_Args>(__args)...);
1371    --__start_;
1372    ++__size();
1373#if _LIBCPP_STD_VER >= 17
1374    return *begin();
1375#endif
1376}
1377
1378template <class _Tp, class _Allocator>
1379typename deque<_Tp, _Allocator>::iterator
1380deque<_Tp, _Allocator>::insert(const_iterator __p, value_type&& __v)
1381{
1382    size_type __pos = __p - begin();
1383    size_type __to_end = size() - __pos;
1384    allocator_type& __a = __alloc();
1385    if (__pos < __to_end)
1386    {   // insert by shifting things backward
1387        if (__front_spare() == 0)
1388            __add_front_capacity();
1389        // __front_spare() >= 1
1390        if (__pos == 0)
1391        {
1392            __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), _VSTD::move(__v));
1393            --__start_;
1394            ++__size();
1395        }
1396        else
1397        {
1398            iterator __b = begin();
1399            iterator __bm1 = _VSTD::prev(__b);
1400            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
1401            --__start_;
1402            ++__size();
1403            if (__pos > 1)
1404                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
1405            *__b = _VSTD::move(__v);
1406        }
1407    }
1408    else
1409    {   // insert by shifting things forward
1410        if (__back_spare() == 0)
1411            __add_back_capacity();
1412        // __back_capacity >= 1
1413        size_type __de = size() - __pos;
1414        if (__de == 0)
1415        {
1416            __alloc_traits::construct(__a, _VSTD::addressof(*end()), _VSTD::move(__v));
1417            ++__size();
1418        }
1419        else
1420        {
1421            iterator __e = end();
1422            iterator __em1 = _VSTD::prev(__e);
1423            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
1424            ++__size();
1425            if (__de > 1)
1426                __e = _VSTD::move_backward(__e - __de, __em1, __e);
1427            *--__e = _VSTD::move(__v);
1428        }
1429    }
1430    return begin() + __pos;
1431}
1432
1433template <class _Tp, class _Allocator>
1434template <class... _Args>
1435typename deque<_Tp, _Allocator>::iterator
1436deque<_Tp, _Allocator>::emplace(const_iterator __p, _Args&&... __args)
1437{
1438    size_type __pos = __p - begin();
1439    size_type __to_end = size() - __pos;
1440    allocator_type& __a = __alloc();
1441    if (__pos < __to_end)
1442    {   // insert by shifting things backward
1443        if (__front_spare() == 0)
1444            __add_front_capacity();
1445        // __front_spare() >= 1
1446        if (__pos == 0)
1447        {
1448            __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), _VSTD::forward<_Args>(__args)...);
1449            --__start_;
1450            ++__size();
1451        }
1452        else
1453        {
1454            __temp_value<value_type, _Allocator> __tmp(__alloc(), _VSTD::forward<_Args>(__args)...);
1455            iterator __b = begin();
1456            iterator __bm1 = _VSTD::prev(__b);
1457            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
1458            --__start_;
1459            ++__size();
1460            if (__pos > 1)
1461                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
1462            *__b = _VSTD::move(__tmp.get());
1463        }
1464    }
1465    else
1466    {   // insert by shifting things forward
1467        if (__back_spare() == 0)
1468            __add_back_capacity();
1469        // __back_capacity >= 1
1470        size_type __de = size() - __pos;
1471        if (__de == 0)
1472        {
1473            __alloc_traits::construct(__a, _VSTD::addressof(*end()), _VSTD::forward<_Args>(__args)...);
1474            ++__size();
1475        }
1476        else
1477        {
1478            __temp_value<value_type, _Allocator> __tmp(__alloc(), _VSTD::forward<_Args>(__args)...);
1479            iterator __e = end();
1480            iterator __em1 = _VSTD::prev(__e);
1481            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
1482            ++__size();
1483            if (__de > 1)
1484                __e = _VSTD::move_backward(__e - __de, __em1, __e);
1485            *--__e = _VSTD::move(__tmp.get());
1486        }
1487    }
1488    return begin() + __pos;
1489}
1490
1491#endif // _LIBCPP_CXX03_LANG
1492
1493
1494template <class _Tp, class _Allocator>
1495typename deque<_Tp, _Allocator>::iterator
1496deque<_Tp, _Allocator>::insert(const_iterator __p, const value_type& __v)
1497{
1498    size_type __pos = __p - begin();
1499    size_type __to_end = size() - __pos;
1500    allocator_type& __a = __alloc();
1501    if (__pos < __to_end)
1502    {   // insert by shifting things backward
1503        if (__front_spare() == 0)
1504            __add_front_capacity();
1505        // __front_spare() >= 1
1506        if (__pos == 0)
1507        {
1508            __alloc_traits::construct(__a, _VSTD::addressof(*--begin()), __v);
1509            --__start_;
1510            ++__size();
1511        }
1512        else
1513        {
1514            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
1515            iterator __b = begin();
1516            iterator __bm1 = _VSTD::prev(__b);
1517            if (__vt == pointer_traits<const_pointer>::pointer_to(*__b))
1518                __vt = pointer_traits<const_pointer>::pointer_to(*__bm1);
1519            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
1520            --__start_;
1521            ++__size();
1522            if (__pos > 1)
1523                __b = __move_and_check(_VSTD::next(__b), __b + __pos, __b, __vt);
1524            *__b = *__vt;
1525        }
1526    }
1527    else
1528    {   // insert by shifting things forward
1529        if (__back_spare() == 0)
1530            __add_back_capacity();
1531        // __back_capacity >= 1
1532        size_type __de = size() - __pos;
1533        if (__de == 0)
1534        {
1535            __alloc_traits::construct(__a, _VSTD::addressof(*end()), __v);
1536            ++__size();
1537        }
1538        else
1539        {
1540            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
1541            iterator __e = end();
1542            iterator __em1 = _VSTD::prev(__e);
1543            if (__vt == pointer_traits<const_pointer>::pointer_to(*__em1))
1544                __vt = pointer_traits<const_pointer>::pointer_to(*__e);
1545            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
1546            ++__size();
1547            if (__de > 1)
1548                __e = __move_backward_and_check(__e - __de, __em1, __e, __vt);
1549            *--__e = *__vt;
1550        }
1551    }
1552    return begin() + __pos;
1553}
1554
1555template <class _Tp, class _Allocator>
1556typename deque<_Tp, _Allocator>::iterator
1557deque<_Tp, _Allocator>::insert(const_iterator __p, size_type __n, const value_type& __v)
1558{
1559    size_type __pos = __p - begin();
1560    size_type __to_end = __size() - __pos;
1561    allocator_type& __a = __alloc();
1562    if (__pos < __to_end)
1563    {   // insert by shifting things backward
1564        if (__n > __front_spare())
1565            __add_front_capacity(__n - __front_spare());
1566        // __n <= __front_spare()
1567        iterator __old_begin = begin();
1568        iterator __i = __old_begin;
1569        if (__n > __pos)
1570        {
1571            for (size_type __m = __n - __pos; __m; --__m, --__start_, ++__size())
1572                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), __v);
1573            __n = __pos;
1574        }
1575        if (__n > 0)
1576        {
1577            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
1578            iterator __obn = __old_begin + __n;
1579            __move_construct_backward_and_check(__old_begin, __obn, __i, __vt);
1580            if (__n < __pos)
1581                __old_begin = __move_and_check(__obn, __old_begin + __pos, __old_begin, __vt);
1582            _VSTD::fill_n(__old_begin, __n, *__vt);
1583        }
1584    }
1585    else
1586    {   // insert by shifting things forward
1587        size_type __back_capacity = __back_spare();
1588        if (__n > __back_capacity)
1589            __add_back_capacity(__n - __back_capacity);
1590        // __n <= __back_capacity
1591        iterator __old_end = end();
1592        iterator __i = __old_end;
1593        size_type __de = size() - __pos;
1594        if (__n > __de)
1595        {
1596            for (size_type __m = __n - __de; __m; --__m, (void) ++__i, ++__size())
1597                __alloc_traits::construct(__a, _VSTD::addressof(*__i), __v);
1598            __n = __de;
1599        }
1600        if (__n > 0)
1601        {
1602            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
1603            iterator __oen = __old_end - __n;
1604            __move_construct_and_check(__oen, __old_end, __i, __vt);
1605            if (__n < __de)
1606                __old_end = __move_backward_and_check(__old_end - __de, __oen, __old_end, __vt);
1607            _VSTD::fill_n(__old_end - __n, __n, *__vt);
1608        }
1609    }
1610    return begin() + __pos;
1611}
1612
1613template <class _Tp, class _Allocator>
1614template <class _InputIter>
1615typename deque<_Tp, _Allocator>::iterator
1616deque<_Tp, _Allocator>::insert(const_iterator __p, _InputIter __f, _InputIter __l,
1617                               typename enable_if<__is_exactly_cpp17_input_iterator<_InputIter>::value>::type*)
1618{
1619    __split_buffer<value_type, allocator_type&> __buf(__alloc());
1620    __buf.__construct_at_end(__f, __l);
1621    typedef typename __split_buffer<value_type, allocator_type&>::iterator __bi;
1622    return insert(__p, move_iterator<__bi>(__buf.begin()), move_iterator<__bi>(__buf.end()));
1623}
1624
1625template <class _Tp, class _Allocator>
1626template <class _ForwardIterator>
1627typename deque<_Tp, _Allocator>::iterator
1628deque<_Tp, _Allocator>::insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
1629                               typename enable_if<__is_exactly_cpp17_forward_iterator<_ForwardIterator>::value>::type*)
1630{
1631    size_type __n = _VSTD::distance(__f, __l);
1632    __split_buffer<value_type, allocator_type&> __buf(__n, 0, __alloc());
1633    __buf.__construct_at_end(__f, __l);
1634    typedef typename __split_buffer<value_type, allocator_type&>::iterator __fwd;
1635    return insert(__p, move_iterator<__fwd>(__buf.begin()), move_iterator<__fwd>(__buf.end()));
1636}
1637
1638template <class _Tp, class _Allocator>
1639template <class _BiIter>
1640typename deque<_Tp, _Allocator>::iterator
1641deque<_Tp, _Allocator>::insert(const_iterator __p, _BiIter __f, _BiIter __l,
1642                               typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type*)
1643{
1644    size_type __n = _VSTD::distance(__f, __l);
1645    size_type __pos = __p - begin();
1646    size_type __to_end = size() - __pos;
1647    allocator_type& __a = __alloc();
1648    if (__pos < __to_end)
1649    {   // insert by shifting things backward
1650        if (__n > __front_spare())
1651            __add_front_capacity(__n - __front_spare());
1652        // __n <= __front_spare()
1653        iterator __old_begin = begin();
1654        iterator __i = __old_begin;
1655        _BiIter __m = __f;
1656        if (__n > __pos)
1657        {
1658            __m = __pos < __n / 2 ? _VSTD::prev(__l, __pos) : _VSTD::next(__f, __n - __pos);
1659            for (_BiIter __j = __m; __j != __f; --__start_, ++__size())
1660                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), *--__j);
1661            __n = __pos;
1662        }
1663        if (__n > 0)
1664        {
1665            iterator __obn = __old_begin + __n;
1666            for (iterator __j = __obn; __j != __old_begin;)
1667            {
1668                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), _VSTD::move(*--__j));
1669                --__start_;
1670                ++__size();
1671            }
1672            if (__n < __pos)
1673                __old_begin = _VSTD::move(__obn, __old_begin + __pos, __old_begin);
1674            _VSTD::copy(__m, __l, __old_begin);
1675        }
1676    }
1677    else
1678    {   // insert by shifting things forward
1679        size_type __back_capacity = __back_spare();
1680        if (__n > __back_capacity)
1681            __add_back_capacity(__n - __back_capacity);
1682        // __n <= __back_capacity
1683        iterator __old_end = end();
1684        iterator __i = __old_end;
1685        _BiIter __m = __l;
1686        size_type __de = size() - __pos;
1687        if (__n > __de)
1688        {
1689            __m = __de < __n / 2 ? _VSTD::next(__f, __de) : _VSTD::prev(__l, __n - __de);
1690            for (_BiIter __j = __m; __j != __l; ++__i, (void) ++__j, ++__size())
1691                __alloc_traits::construct(__a, _VSTD::addressof(*__i), *__j);
1692            __n = __de;
1693        }
1694        if (__n > 0)
1695        {
1696            iterator __oen = __old_end - __n;
1697            for (iterator __j = __oen; __j != __old_end; ++__i, (void) ++__j, ++__size())
1698                __alloc_traits::construct(__a, _VSTD::addressof(*__i), _VSTD::move(*__j));
1699            if (__n < __de)
1700                __old_end = _VSTD::move_backward(__old_end - __de, __oen, __old_end);
1701            _VSTD::copy_backward(__f, __m, __old_end);
1702        }
1703    }
1704    return begin() + __pos;
1705}
1706
1707template <class _Tp, class _Allocator>
1708template <class _InpIter>
1709void
1710deque<_Tp, _Allocator>::__append(_InpIter __f, _InpIter __l,
1711                                 typename enable_if<__is_exactly_cpp17_input_iterator<_InpIter>::value>::type*)
1712{
1713    for (; __f != __l; ++__f)
1714#ifdef _LIBCPP_CXX03_LANG
1715        push_back(*__f);
1716#else
1717        emplace_back(*__f);
1718#endif
1719}
1720
1721template <class _Tp, class _Allocator>
1722template <class _ForIter>
1723void
1724deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l,
1725                                 typename enable_if<__is_cpp17_forward_iterator<_ForIter>::value>::type*)
1726{
1727    size_type __n = _VSTD::distance(__f, __l);
1728    allocator_type& __a = __alloc();
1729    size_type __back_capacity = __back_spare();
1730    if (__n > __back_capacity)
1731        __add_back_capacity(__n - __back_capacity);
1732    // __n <= __back_capacity
1733    for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
1734      _ConstructTransaction __tx(this, __br);
1735      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) {
1736        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), *__f);
1737      }
1738    }
1739}
1740
1741template <class _Tp, class _Allocator>
1742void
1743deque<_Tp, _Allocator>::__append(size_type __n)
1744{
1745    allocator_type& __a = __alloc();
1746    size_type __back_capacity = __back_spare();
1747    if (__n > __back_capacity)
1748        __add_back_capacity(__n - __back_capacity);
1749    // __n <= __back_capacity
1750    for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
1751      _ConstructTransaction __tx(this, __br);
1752      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
1753        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_));
1754      }
1755    }
1756}
1757
1758template <class _Tp, class _Allocator>
1759void
1760deque<_Tp, _Allocator>::__append(size_type __n, const value_type& __v)
1761{
1762    allocator_type& __a = __alloc();
1763    size_type __back_capacity = __back_spare();
1764    if (__n > __back_capacity)
1765        __add_back_capacity(__n - __back_capacity);
1766    // __n <= __back_capacity
1767    for (__deque_block_range __br : __deque_range(end(), end() + __n)) {
1768      _ConstructTransaction __tx(this, __br);
1769      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
1770        __alloc_traits::construct(__a, _VSTD::__to_address(__tx.__pos_), __v);
1771      }
1772    }
1773
1774}
1775
1776// Create front capacity for one block of elements.
1777// Strong guarantee.  Either do it or don't touch anything.
1778template <class _Tp, class _Allocator>
1779void
1780deque<_Tp, _Allocator>::__add_front_capacity()
1781{
1782    allocator_type& __a = __alloc();
1783    if (__back_spare() >= __block_size)
1784    {
1785        __start_ += __block_size;
1786        pointer __pt = __map_.back();
1787        __map_.pop_back();
1788        __map_.push_front(__pt);
1789    }
1790    // Else if __map_.size() < __map_.capacity() then we need to allocate 1 buffer
1791    else if (__map_.size() < __map_.capacity())
1792    {   // we can put the new buffer into the map, but don't shift things around
1793        // until all buffers are allocated.  If we throw, we don't need to fix
1794        // anything up (any added buffers are undetectible)
1795        if (__map_.__front_spare() > 0)
1796            __map_.push_front(__alloc_traits::allocate(__a, __block_size));
1797        else
1798        {
1799            __map_.push_back(__alloc_traits::allocate(__a, __block_size));
1800            // Done allocating, reorder capacity
1801            pointer __pt = __map_.back();
1802            __map_.pop_back();
1803            __map_.push_front(__pt);
1804        }
1805        __start_ = __map_.size() == 1 ?
1806                               __block_size / 2 :
1807                               __start_ + __block_size;
1808    }
1809    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
1810    else
1811    {
1812        __split_buffer<pointer, __pointer_allocator&>
1813            __buf(std::max<size_type>(2 * __map_.capacity(), 1),
1814                  0, __map_.__alloc());
1815
1816        typedef __allocator_destructor<_Allocator> _Dp;
1817        unique_ptr<pointer, _Dp> __hold(
1818            __alloc_traits::allocate(__a, __block_size),
1819                _Dp(__a, __block_size));
1820        __buf.push_back(__hold.get());
1821        __hold.release();
1822
1823        for (__map_pointer __i = __map_.begin();
1824                __i != __map_.end(); ++__i)
1825            __buf.push_back(*__i);
1826        _VSTD::swap(__map_.__first_, __buf.__first_);
1827        _VSTD::swap(__map_.__begin_, __buf.__begin_);
1828        _VSTD::swap(__map_.__end_, __buf.__end_);
1829        _VSTD::swap(__map_.__end_cap(), __buf.__end_cap());
1830        __start_ = __map_.size() == 1 ?
1831                               __block_size / 2 :
1832                               __start_ + __block_size;
1833    }
1834}
1835
1836// Create front capacity for __n elements.
1837// Strong guarantee.  Either do it or don't touch anything.
1838template <class _Tp, class _Allocator>
1839void
1840deque<_Tp, _Allocator>::__add_front_capacity(size_type __n)
1841{
1842    allocator_type& __a = __alloc();
1843    size_type __nb = __recommend_blocks(__n + __map_.empty());
1844    // Number of unused blocks at back:
1845    size_type __back_capacity = __back_spare() / __block_size;
1846    __back_capacity = _VSTD::min(__back_capacity, __nb);  // don't take more than you need
1847    __nb -= __back_capacity;  // number of blocks need to allocate
1848    // If __nb == 0, then we have sufficient capacity.
1849    if (__nb == 0)
1850    {
1851        __start_ += __block_size * __back_capacity;
1852        for (; __back_capacity > 0; --__back_capacity)
1853        {
1854            pointer __pt = __map_.back();
1855            __map_.pop_back();
1856            __map_.push_front(__pt);
1857        }
1858    }
1859    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
1860    else if (__nb <= __map_.capacity() - __map_.size())
1861    {   // we can put the new buffers into the map, but don't shift things around
1862        // until all buffers are allocated.  If we throw, we don't need to fix
1863        // anything up (any added buffers are undetectible)
1864        for (; __nb > 0; --__nb, __start_ += __block_size - (__map_.size() == 1))
1865        {
1866            if (__map_.__front_spare() == 0)
1867                break;
1868            __map_.push_front(__alloc_traits::allocate(__a, __block_size));
1869        }
1870        for (; __nb > 0; --__nb, ++__back_capacity)
1871            __map_.push_back(__alloc_traits::allocate(__a, __block_size));
1872        // Done allocating, reorder capacity
1873        __start_ += __back_capacity * __block_size;
1874        for (; __back_capacity > 0; --__back_capacity)
1875        {
1876            pointer __pt = __map_.back();
1877            __map_.pop_back();
1878            __map_.push_front(__pt);
1879        }
1880    }
1881    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
1882    else
1883    {
1884        size_type __ds = (__nb + __back_capacity) * __block_size - __map_.empty();
1885        __split_buffer<pointer, __pointer_allocator&>
1886            __buf(std::max<size_type>(2* __map_.capacity(),
1887                                      __nb + __map_.size()),
1888                  0, __map_.__alloc());
1889#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1890        try
1891        {
1892#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1893            for (; __nb > 0; --__nb)
1894                __buf.push_back(__alloc_traits::allocate(__a, __block_size));
1895#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
1896        }
1897        catch (...)
1898        {
1899            for (__map_pointer __i = __buf.begin();
1900                    __i != __buf.end(); ++__i)
1901                __alloc_traits::deallocate(__a, *__i, __block_size);
1902            throw;
1903        }
1904#endif // _LIBCPP_HAS_NO_EXCEPTIONS
1905        for (; __back_capacity > 0; --__back_capacity)
1906        {
1907            __buf.push_back(__map_.back());
1908            __map_.pop_back();
1909        }
1910        for (__map_pointer __i = __map_.begin();
1911                __i != __map_.end(); ++__i)
1912            __buf.push_back(*__i);
1913        _VSTD::swap(__map_.__first_, __buf.__first_);
1914        _VSTD::swap(__map_.__begin_, __buf.__begin_);
1915        _VSTD::swap(__map_.__end_, __buf.__end_);
1916        _VSTD::swap(__map_.__end_cap(), __buf.__end_cap());
1917        __start_ += __ds;
1918    }
1919}
1920
1921// Create back capacity for one block of elements.
1922// Strong guarantee.  Either do it or don't touch anything.
1923template <class _Tp, class _Allocator>
1924void
1925deque<_Tp, _Allocator>::__add_back_capacity()
1926{
1927    allocator_type& __a = __alloc();
1928    if (__front_spare() >= __block_size)
1929    {
1930        __start_ -= __block_size;
1931        pointer __pt = __map_.front();
1932        __map_.pop_front();
1933        __map_.push_back(__pt);
1934    }
1935    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
1936    else if (__map_.size() < __map_.capacity())
1937    {   // we can put the new buffer into the map, but don't shift things around
1938        // until it is allocated.  If we throw, we don't need to fix
1939        // anything up (any added buffers are undetectible)
1940        if (__map_.__back_spare() != 0)
1941            __map_.push_back(__alloc_traits::allocate(__a, __block_size));
1942        else
1943        {
1944            __map_.push_front(__alloc_traits::allocate(__a, __block_size));
1945            // Done allocating, reorder capacity
1946            pointer __pt = __map_.front();
1947            __map_.pop_front();
1948            __map_.push_back(__pt);
1949        }
1950    }
1951    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
1952    else
1953    {
1954        __split_buffer<pointer, __pointer_allocator&>
1955            __buf(std::max<size_type>(2* __map_.capacity(), 1),
1956                  __map_.size(),
1957                  __map_.__alloc());
1958
1959        typedef __allocator_destructor<_Allocator> _Dp;
1960        unique_ptr<pointer, _Dp> __hold(
1961            __alloc_traits::allocate(__a, __block_size),
1962                _Dp(__a, __block_size));
1963        __buf.push_back(__hold.get());
1964        __hold.release();
1965
1966        for (__map_pointer __i = __map_.end();
1967                __i != __map_.begin();)
1968            __buf.push_front(*--__i);
1969        _VSTD::swap(__map_.__first_, __buf.__first_);
1970        _VSTD::swap(__map_.__begin_, __buf.__begin_);
1971        _VSTD::swap(__map_.__end_, __buf.__end_);
1972        _VSTD::swap(__map_.__end_cap(), __buf.__end_cap());
1973    }
1974}
1975
1976// Create back capacity for __n elements.
1977// Strong guarantee.  Either do it or don't touch anything.
1978template <class _Tp, class _Allocator>
1979void
1980deque<_Tp, _Allocator>::__add_back_capacity(size_type __n)
1981{
1982    allocator_type& __a = __alloc();
1983    size_type __nb = __recommend_blocks(__n + __map_.empty());
1984    // Number of unused blocks at front:
1985    size_type __front_capacity = __front_spare() / __block_size;
1986    __front_capacity = _VSTD::min(__front_capacity, __nb);  // don't take more than you need
1987    __nb -= __front_capacity;  // number of blocks need to allocate
1988    // If __nb == 0, then we have sufficient capacity.
1989    if (__nb == 0)
1990    {
1991        __start_ -= __block_size * __front_capacity;
1992        for (; __front_capacity > 0; --__front_capacity)
1993        {
1994            pointer __pt = __map_.front();
1995            __map_.pop_front();
1996            __map_.push_back(__pt);
1997        }
1998    }
1999    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
2000    else if (__nb <= __map_.capacity() - __map_.size())
2001    {   // we can put the new buffers into the map, but don't shift things around
2002        // until all buffers are allocated.  If we throw, we don't need to fix
2003        // anything up (any added buffers are undetectible)
2004        for (; __nb > 0; --__nb)
2005        {
2006            if (__map_.__back_spare() == 0)
2007                break;
2008            __map_.push_back(__alloc_traits::allocate(__a, __block_size));
2009        }
2010        for (; __nb > 0; --__nb, ++__front_capacity, __start_ +=
2011                                 __block_size - (__map_.size() == 1))
2012            __map_.push_front(__alloc_traits::allocate(__a, __block_size));
2013        // Done allocating, reorder capacity
2014        __start_ -= __block_size * __front_capacity;
2015        for (; __front_capacity > 0; --__front_capacity)
2016        {
2017            pointer __pt = __map_.front();
2018            __map_.pop_front();
2019            __map_.push_back(__pt);
2020        }
2021    }
2022    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
2023    else
2024    {
2025        size_type __ds = __front_capacity * __block_size;
2026        __split_buffer<pointer, __pointer_allocator&>
2027            __buf(std::max<size_type>(2* __map_.capacity(),
2028                                      __nb + __map_.size()),
2029                  __map_.size() - __front_capacity,
2030                  __map_.__alloc());
2031#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
2032        try
2033        {
2034#endif // _LIBCPP_HAS_NO_EXCEPTIONS
2035            for (; __nb > 0; --__nb)
2036                __buf.push_back(__alloc_traits::allocate(__a, __block_size));
2037#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
2038        }
2039        catch (...)
2040        {
2041            for (__map_pointer __i = __buf.begin();
2042                    __i != __buf.end(); ++__i)
2043                __alloc_traits::deallocate(__a, *__i, __block_size);
2044            throw;
2045        }
2046#endif // _LIBCPP_HAS_NO_EXCEPTIONS
2047        for (; __front_capacity > 0; --__front_capacity)
2048        {
2049            __buf.push_back(__map_.front());
2050            __map_.pop_front();
2051        }
2052        for (__map_pointer __i = __map_.end();
2053                __i != __map_.begin();)
2054            __buf.push_front(*--__i);
2055        _VSTD::swap(__map_.__first_, __buf.__first_);
2056        _VSTD::swap(__map_.__begin_, __buf.__begin_);
2057        _VSTD::swap(__map_.__end_, __buf.__end_);
2058        _VSTD::swap(__map_.__end_cap(), __buf.__end_cap());
2059        __start_ -= __ds;
2060    }
2061}
2062
2063template <class _Tp, class _Allocator>
2064void
2065deque<_Tp, _Allocator>::pop_front()
2066{
2067    allocator_type& __a = __alloc();
2068    __alloc_traits::destroy(__a, _VSTD::__to_address(*(__map_.begin() +
2069                                                    __start_ / __block_size) +
2070                                                    __start_ % __block_size));
2071    --__size();
2072    ++__start_;
2073    __maybe_remove_front_spare();
2074}
2075
2076template <class _Tp, class _Allocator>
2077void
2078deque<_Tp, _Allocator>::pop_back()
2079{
2080    _LIBCPP_ASSERT(!empty(), "deque::pop_back called on an empty deque");
2081    allocator_type& __a = __alloc();
2082    size_type __p = size() + __start_ - 1;
2083    __alloc_traits::destroy(__a, _VSTD::__to_address(*(__map_.begin() +
2084                                                    __p / __block_size) +
2085                                                    __p % __block_size));
2086    --__size();
2087    __maybe_remove_back_spare();
2088}
2089
2090// move assign [__f, __l) to [__r, __r + (__l-__f)).
2091// If __vt points into [__f, __l), then subtract (__f - __r) from __vt.
2092template <class _Tp, class _Allocator>
2093typename deque<_Tp, _Allocator>::iterator
2094deque<_Tp, _Allocator>::__move_and_check(iterator __f, iterator __l, iterator __r,
2095                                         const_pointer& __vt)
2096{
2097    // as if
2098    //   for (; __f != __l; ++__f, ++__r)
2099    //       *__r = _VSTD::move(*__f);
2100    difference_type __n = __l - __f;
2101    while (__n > 0)
2102    {
2103        pointer __fb = __f.__ptr_;
2104        pointer __fe = *__f.__m_iter_ + __block_size;
2105        difference_type __bs = __fe - __fb;
2106        if (__bs > __n)
2107        {
2108            __bs = __n;
2109            __fe = __fb + __bs;
2110        }
2111        if (__fb <= __vt && __vt < __fe)
2112            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) -= __f - __r).__ptr_;
2113        __r = _VSTD::move(__fb, __fe, __r);
2114        __n -= __bs;
2115        __f += __bs;
2116    }
2117    return __r;
2118}
2119
2120// move assign [__f, __l) to [__r - (__l-__f), __r) backwards.
2121// If __vt points into [__f, __l), then add (__r - __l) to __vt.
2122template <class _Tp, class _Allocator>
2123typename deque<_Tp, _Allocator>::iterator
2124deque<_Tp, _Allocator>::__move_backward_and_check(iterator __f, iterator __l, iterator __r,
2125                                                  const_pointer& __vt)
2126{
2127    // as if
2128    //   while (__f != __l)
2129    //       *--__r = _VSTD::move(*--__l);
2130    difference_type __n = __l - __f;
2131    while (__n > 0)
2132    {
2133        --__l;
2134        pointer __lb = *__l.__m_iter_;
2135        pointer __le = __l.__ptr_ + 1;
2136        difference_type __bs = __le - __lb;
2137        if (__bs > __n)
2138        {
2139            __bs = __n;
2140            __lb = __le - __bs;
2141        }
2142        if (__lb <= __vt && __vt < __le)
2143            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) += __r - __l - 1).__ptr_;
2144        __r = _VSTD::move_backward(__lb, __le, __r);
2145        __n -= __bs;
2146        __l -= __bs - 1;
2147    }
2148    return __r;
2149}
2150
2151// move construct [__f, __l) to [__r, __r + (__l-__f)).
2152// If __vt points into [__f, __l), then add (__r - __f) to __vt.
2153template <class _Tp, class _Allocator>
2154void
2155deque<_Tp, _Allocator>::__move_construct_and_check(iterator __f, iterator __l,
2156                                                   iterator __r, const_pointer& __vt)
2157{
2158    allocator_type& __a = __alloc();
2159    // as if
2160    //   for (; __f != __l; ++__r, ++__f, ++__size())
2161    //       __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__f));
2162    difference_type __n = __l - __f;
2163    while (__n > 0)
2164    {
2165        pointer __fb = __f.__ptr_;
2166        pointer __fe = *__f.__m_iter_ + __block_size;
2167        difference_type __bs = __fe - __fb;
2168        if (__bs > __n)
2169        {
2170            __bs = __n;
2171            __fe = __fb + __bs;
2172        }
2173        if (__fb <= __vt && __vt < __fe)
2174            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) += __r - __f).__ptr_;
2175        for (; __fb != __fe; ++__fb, ++__r, ++__size())
2176            __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__fb));
2177        __n -= __bs;
2178        __f += __bs;
2179    }
2180}
2181
2182// move construct [__f, __l) to [__r - (__l-__f), __r) backwards.
2183// If __vt points into [__f, __l), then subtract (__l - __r) from __vt.
2184template <class _Tp, class _Allocator>
2185void
2186deque<_Tp, _Allocator>::__move_construct_backward_and_check(iterator __f, iterator __l,
2187                                                            iterator __r, const_pointer& __vt)
2188{
2189    allocator_type& __a = __alloc();
2190    // as if
2191    //   for (iterator __j = __l; __j != __f;)
2192    //   {
2193    //       __alloc_traitsconstruct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__j));
2194    //       --__start_;
2195    //       ++__size();
2196    //   }
2197    difference_type __n = __l - __f;
2198    while (__n > 0)
2199    {
2200        --__l;
2201        pointer __lb = *__l.__m_iter_;
2202        pointer __le = __l.__ptr_ + 1;
2203        difference_type __bs = __le - __lb;
2204        if (__bs > __n)
2205        {
2206            __bs = __n;
2207            __lb = __le - __bs;
2208        }
2209        if (__lb <= __vt && __vt < __le)
2210            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) -= __l - __r + 1).__ptr_;
2211        while (__le != __lb)
2212        {
2213            __alloc_traits::construct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__le));
2214            --__start_;
2215            ++__size();
2216        }
2217        __n -= __bs;
2218        __l -= __bs - 1;
2219    }
2220}
2221
2222template <class _Tp, class _Allocator>
2223typename deque<_Tp, _Allocator>::iterator
2224deque<_Tp, _Allocator>::erase(const_iterator __f)
2225{
2226    iterator __b = begin();
2227    difference_type __pos = __f - __b;
2228    iterator __p = __b + __pos;
2229    allocator_type& __a = __alloc();
2230    if (static_cast<size_t>(__pos) <= (size() - 1) / 2)
2231    {   // erase from front
2232        _VSTD::move_backward(__b, __p, _VSTD::next(__p));
2233        __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
2234        --__size();
2235        ++__start_;
2236        __maybe_remove_front_spare();
2237    }
2238    else
2239    {   // erase from back
2240        iterator __i = _VSTD::move(_VSTD::next(__p), end(), __p);
2241        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
2242        --__size();
2243        __maybe_remove_back_spare();
2244    }
2245    return begin() + __pos;
2246}
2247
2248template <class _Tp, class _Allocator>
2249typename deque<_Tp, _Allocator>::iterator
2250deque<_Tp, _Allocator>::erase(const_iterator __f, const_iterator __l)
2251{
2252    difference_type __n = __l - __f;
2253    iterator __b = begin();
2254    difference_type __pos = __f - __b;
2255    iterator __p = __b + __pos;
2256    if (__n > 0)
2257    {
2258        allocator_type& __a = __alloc();
2259        if (static_cast<size_t>(__pos) <= (size() - __n) / 2)
2260        {   // erase from front
2261            iterator __i = _VSTD::move_backward(__b, __p, __p + __n);
2262            for (; __b != __i; ++__b)
2263                __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
2264            __size() -= __n;
2265            __start_ += __n;
2266            while (__maybe_remove_front_spare()) {
2267            }
2268        }
2269        else
2270        {   // erase from back
2271            iterator __i = _VSTD::move(__p + __n, end(), __p);
2272            for (iterator __e = end(); __i != __e; ++__i)
2273                __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
2274            __size() -= __n;
2275            while (__maybe_remove_back_spare()) {
2276            }
2277        }
2278    }
2279    return begin() + __pos;
2280}
2281
2282template <class _Tp, class _Allocator>
2283void
2284deque<_Tp, _Allocator>::__erase_to_end(const_iterator __f)
2285{
2286    iterator __e = end();
2287    difference_type __n = __e - __f;
2288    if (__n > 0)
2289    {
2290        allocator_type& __a = __alloc();
2291        iterator __b = begin();
2292        difference_type __pos = __f - __b;
2293        for (iterator __p = __b + __pos; __p != __e; ++__p)
2294            __alloc_traits::destroy(__a, _VSTD::addressof(*__p));
2295        __size() -= __n;
2296        while (__maybe_remove_back_spare()) {
2297        }
2298    }
2299}
2300
2301template <class _Tp, class _Allocator>
2302inline
2303void
2304deque<_Tp, _Allocator>::swap(deque& __c)
2305#if _LIBCPP_STD_VER >= 14
2306        _NOEXCEPT
2307#else
2308        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
2309                    __is_nothrow_swappable<allocator_type>::value)
2310#endif
2311{
2312    __map_.swap(__c.__map_);
2313    _VSTD::swap(__start_, __c.__start_);
2314    _VSTD::swap(__size(), __c.__size());
2315    _VSTD::__swap_allocator(__alloc(), __c.__alloc());
2316}
2317
2318template <class _Tp, class _Allocator>
2319inline
2320void
2321deque<_Tp, _Allocator>::clear() _NOEXCEPT
2322{
2323    allocator_type& __a = __alloc();
2324    for (iterator __i = begin(), __e = end(); __i != __e; ++__i)
2325        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
2326    __size() = 0;
2327    while (__map_.size() > 2)
2328    {
2329        __alloc_traits::deallocate(__a, __map_.front(), __block_size);
2330        __map_.pop_front();
2331    }
2332    switch (__map_.size())
2333    {
2334    case 1:
2335        __start_ = __block_size / 2;
2336        break;
2337    case 2:
2338        __start_ = __block_size;
2339        break;
2340    }
2341}
2342
2343template <class _Tp, class _Allocator>
2344inline _LIBCPP_HIDE_FROM_ABI
2345bool
2346operator==(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2347{
2348    const typename deque<_Tp, _Allocator>::size_type __sz = __x.size();
2349    return __sz == __y.size() && _VSTD::equal(__x.begin(), __x.end(), __y.begin());
2350}
2351
2352#if _LIBCPP_STD_VER <= 17
2353
2354template <class _Tp, class _Allocator>
2355inline _LIBCPP_HIDE_FROM_ABI
2356bool
2357operator!=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2358{
2359    return !(__x == __y);
2360}
2361
2362template <class _Tp, class _Allocator>
2363inline _LIBCPP_HIDE_FROM_ABI
2364bool
2365operator< (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2366{
2367    return _VSTD::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
2368}
2369
2370template <class _Tp, class _Allocator>
2371inline _LIBCPP_HIDE_FROM_ABI
2372bool
2373operator> (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2374{
2375    return __y < __x;
2376}
2377
2378template <class _Tp, class _Allocator>
2379inline _LIBCPP_HIDE_FROM_ABI
2380bool
2381operator>=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2382{
2383    return !(__x < __y);
2384}
2385
2386template <class _Tp, class _Allocator>
2387inline _LIBCPP_HIDE_FROM_ABI
2388bool
2389operator<=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2390{
2391    return !(__y < __x);
2392}
2393
2394#else // _LIBCPP_STD_VER <= 17
2395
2396template<class _Tp, class _Allocator>
2397inline _LIBCPP_HIDE_FROM_ABI
2398__synth_three_way_result<_Tp>
2399operator<=>(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2400{
2401    return std::lexicographical_compare_three_way(
2402        __x.begin(), __x.end(), __y.begin(), __y.end(), std::__synth_three_way<_Tp, _Tp>);
2403}
2404
2405#endif // _LIBCPP_STD_VER <= 17
2406
2407template <class _Tp, class _Allocator>
2408inline _LIBCPP_HIDE_FROM_ABI
2409void
2410swap(deque<_Tp, _Allocator>& __x, deque<_Tp, _Allocator>& __y)
2411    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
2412{
2413    __x.swap(__y);
2414}
2415
2416#if _LIBCPP_STD_VER >= 20
2417template <class _Tp, class _Allocator, class _Up>
2418inline _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::size_type
2419erase(deque<_Tp, _Allocator>& __c, const _Up& __v) {
2420  auto __old_size = __c.size();
2421  __c.erase(_VSTD::remove(__c.begin(), __c.end(), __v), __c.end());
2422  return __old_size - __c.size();
2423}
2424
2425template <class _Tp, class _Allocator, class _Predicate>
2426inline _LIBCPP_HIDE_FROM_ABI typename deque<_Tp, _Allocator>::size_type
2427erase_if(deque<_Tp, _Allocator>& __c, _Predicate __pred) {
2428  auto __old_size = __c.size();
2429  __c.erase(_VSTD::remove_if(__c.begin(), __c.end(), __pred), __c.end());
2430  return __old_size - __c.size();
2431}
2432
2433template <>
2434inline constexpr bool __format::__enable_insertable<std::deque<char>> = true;
2435#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
2436template <>
2437inline constexpr bool __format::__enable_insertable<std::deque<wchar_t>> = true;
2438#endif
2439
2440#endif // _LIBCPP_STD_VER >= 20
2441
2442_LIBCPP_END_NAMESPACE_STD
2443
2444#if _LIBCPP_STD_VER >= 17
2445_LIBCPP_BEGIN_NAMESPACE_STD
2446namespace pmr {
2447template <class _ValueT>
2448using deque = std::deque<_ValueT, polymorphic_allocator<_ValueT>>;
2449} // namespace pmr
2450_LIBCPP_END_NAMESPACE_STD
2451#endif
2452
2453_LIBCPP_POP_MACROS
2454
2455#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
2456#  include <algorithm>
2457#  include <atomic>
2458#  include <concepts>
2459#  include <cstdlib>
2460#  include <functional>
2461#  include <iosfwd>
2462#  include <iterator>
2463#  include <type_traits>
2464#  include <typeinfo>
2465#endif
2466
2467#endif // _LIBCPP_DEQUE
2468