xref: /freebsd/contrib/llvm-project/libcxx/include/deque (revision c66ec88fed842fbaad62c30d510644ceb7bd2d71)
1// -*- C++ -*-
2//===---------------------------- deque -----------------------------------===//
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>;
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);
138template <class T, class Allocator>
139    bool operator!=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
140template <class T, class Allocator>
141    bool operator> (const deque<T,Allocator>& x, const deque<T,Allocator>& y);
142template <class T, class Allocator>
143    bool operator>=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
144template <class T, class Allocator>
145    bool operator<=(const deque<T,Allocator>& x, const deque<T,Allocator>& y);
146
147// specialized algorithms:
148template <class T, class Allocator>
149    void swap(deque<T,Allocator>& x, deque<T,Allocator>& y)
150         noexcept(noexcept(x.swap(y)));
151
152template <class T, class Allocator, class U>
153    typename deque<T, Allocator>::size_type
154    erase(deque<T, Allocator>& c, const U& value);       // C++20
155template <class T, class Allocator, class Predicate>
156    typename deque<T, Allocator>::size_type
157    erase_if(deque<T, Allocator>& c, Predicate pred);    // C++20
158
159}  // std
160
161*/
162
163#include <__config>
164#include <__split_buffer>
165#include <type_traits>
166#include <initializer_list>
167#include <iterator>
168#include <algorithm>
169#include <stdexcept>
170#include <version>
171
172#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
173#pragma GCC system_header
174#endif
175
176_LIBCPP_PUSH_MACROS
177#include <__undef_macros>
178
179
180_LIBCPP_BEGIN_NAMESPACE_STD
181
182template <class _Tp, class _Allocator> class __deque_base;
183template <class _Tp, class _Allocator = allocator<_Tp> > class _LIBCPP_TEMPLATE_VIS deque;
184
185template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
186          class _DiffType, _DiffType _BlockSize>
187class _LIBCPP_TEMPLATE_VIS __deque_iterator;
188
189template <class _RAIter,
190          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
191__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
192copy(_RAIter __f,
193     _RAIter __l,
194     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
195     typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
196
197template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
198          class _OutputIterator>
199_OutputIterator
200copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
201     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
202     _OutputIterator __r);
203
204template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
205          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
206__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
207copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
208     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
209     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
210
211template <class _RAIter,
212          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
213__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
214copy_backward(_RAIter __f,
215              _RAIter __l,
216              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
217              typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
218
219template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
220          class _OutputIterator>
221_OutputIterator
222copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
223              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
224              _OutputIterator __r);
225
226template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
227          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
228__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
229copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
230              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
231              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
232
233template <class _RAIter,
234          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
235__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
236move(_RAIter __f,
237     _RAIter __l,
238     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
239     typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
240
241template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
242          class _OutputIterator>
243_OutputIterator
244move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
245     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
246     _OutputIterator __r);
247
248template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
249          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
250__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
251move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
252     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
253     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
254
255template <class _RAIter,
256          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
257__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
258move_backward(_RAIter __f,
259              _RAIter __l,
260              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
261              typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
262
263template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
264          class _OutputIterator>
265_OutputIterator
266move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
267              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
268              _OutputIterator __r);
269
270template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
271          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
272__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
273move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
274              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
275              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
276
277template <class _ValueType, class _DiffType>
278struct __deque_block_size {
279  static const _DiffType value = sizeof(_ValueType) < 256 ? 4096 / sizeof(_ValueType) : 16;
280};
281
282template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
283          class _DiffType, _DiffType _BS =
284#ifdef _LIBCPP_ABI_INCOMPLETE_TYPES_IN_DEQUE
285// Keep template parameter to avoid changing all template declarations thoughout
286// this file.
287                               0
288#else
289                               __deque_block_size<_ValueType, _DiffType>::value
290#endif
291          >
292class _LIBCPP_TEMPLATE_VIS __deque_iterator
293{
294    typedef _MapPointer __map_iterator;
295public:
296    typedef _Pointer  pointer;
297    typedef _DiffType difference_type;
298private:
299    __map_iterator __m_iter_;
300    pointer        __ptr_;
301
302    static const difference_type __block_size;
303public:
304    typedef _ValueType                  value_type;
305    typedef random_access_iterator_tag  iterator_category;
306    typedef _Reference                  reference;
307
308    _LIBCPP_INLINE_VISIBILITY __deque_iterator() _NOEXCEPT
309#if _LIBCPP_STD_VER > 11
310     : __m_iter_(nullptr), __ptr_(nullptr)
311#endif
312     {}
313
314    template <class _Pp, class _Rp, class _MP>
315    _LIBCPP_INLINE_VISIBILITY
316    __deque_iterator(const __deque_iterator<value_type, _Pp, _Rp, _MP, difference_type, _BS>& __it,
317                typename enable_if<is_convertible<_Pp, pointer>::value>::type* = 0) _NOEXCEPT
318        : __m_iter_(__it.__m_iter_), __ptr_(__it.__ptr_) {}
319
320    _LIBCPP_INLINE_VISIBILITY reference operator*() const {return *__ptr_;}
321    _LIBCPP_INLINE_VISIBILITY pointer operator->() const {return __ptr_;}
322
323    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator++()
324    {
325        if (++__ptr_ - *__m_iter_ == __block_size)
326        {
327            ++__m_iter_;
328            __ptr_ = *__m_iter_;
329        }
330        return *this;
331    }
332
333    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator++(int)
334    {
335        __deque_iterator __tmp = *this;
336        ++(*this);
337        return __tmp;
338    }
339
340    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator--()
341    {
342        if (__ptr_ == *__m_iter_)
343        {
344            --__m_iter_;
345            __ptr_ = *__m_iter_ + __block_size;
346        }
347        --__ptr_;
348        return *this;
349    }
350
351    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator--(int)
352    {
353        __deque_iterator __tmp = *this;
354        --(*this);
355        return __tmp;
356    }
357
358    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator+=(difference_type __n)
359    {
360        if (__n != 0)
361        {
362            __n += __ptr_ - *__m_iter_;
363            if (__n > 0)
364            {
365                __m_iter_ += __n / __block_size;
366                __ptr_ = *__m_iter_ + __n % __block_size;
367            }
368            else // (__n < 0)
369            {
370                difference_type __z = __block_size - 1 - __n;
371                __m_iter_ -= __z / __block_size;
372                __ptr_ = *__m_iter_ + (__block_size - 1 - __z % __block_size);
373            }
374        }
375        return *this;
376    }
377
378    _LIBCPP_INLINE_VISIBILITY __deque_iterator& operator-=(difference_type __n)
379    {
380        return *this += -__n;
381    }
382
383    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator+(difference_type __n) const
384    {
385        __deque_iterator __t(*this);
386        __t += __n;
387        return __t;
388    }
389
390    _LIBCPP_INLINE_VISIBILITY __deque_iterator operator-(difference_type __n) const
391    {
392        __deque_iterator __t(*this);
393        __t -= __n;
394        return __t;
395    }
396
397    _LIBCPP_INLINE_VISIBILITY
398    friend __deque_iterator operator+(difference_type __n, const __deque_iterator& __it)
399        {return __it + __n;}
400
401    _LIBCPP_INLINE_VISIBILITY
402    friend difference_type operator-(const __deque_iterator& __x, const __deque_iterator& __y)
403    {
404        if (__x != __y)
405            return (__x.__m_iter_ - __y.__m_iter_) * __block_size
406                 + (__x.__ptr_ - *__x.__m_iter_)
407                 - (__y.__ptr_ - *__y.__m_iter_);
408        return 0;
409    }
410
411    _LIBCPP_INLINE_VISIBILITY reference operator[](difference_type __n) const
412        {return *(*this + __n);}
413
414    _LIBCPP_INLINE_VISIBILITY friend
415        bool operator==(const __deque_iterator& __x, const __deque_iterator& __y)
416        {return __x.__ptr_ == __y.__ptr_;}
417
418    _LIBCPP_INLINE_VISIBILITY friend
419        bool operator!=(const __deque_iterator& __x, const __deque_iterator& __y)
420        {return !(__x == __y);}
421
422    _LIBCPP_INLINE_VISIBILITY friend
423        bool operator<(const __deque_iterator& __x, const __deque_iterator& __y)
424        {return __x.__m_iter_ < __y.__m_iter_ ||
425               (__x.__m_iter_ == __y.__m_iter_ && __x.__ptr_ < __y.__ptr_);}
426
427    _LIBCPP_INLINE_VISIBILITY friend
428        bool operator>(const __deque_iterator& __x, const __deque_iterator& __y)
429        {return __y < __x;}
430
431    _LIBCPP_INLINE_VISIBILITY friend
432        bool operator<=(const __deque_iterator& __x, const __deque_iterator& __y)
433        {return !(__y < __x);}
434
435    _LIBCPP_INLINE_VISIBILITY friend
436        bool operator>=(const __deque_iterator& __x, const __deque_iterator& __y)
437        {return !(__x < __y);}
438
439private:
440    _LIBCPP_INLINE_VISIBILITY __deque_iterator(__map_iterator __m, pointer __p) _NOEXCEPT
441        : __m_iter_(__m), __ptr_(__p) {}
442
443    template <class _Tp, class _Ap> friend class __deque_base;
444    template <class _Tp, class _Ap> friend class _LIBCPP_TEMPLATE_VIS deque;
445    template <class _Vp, class _Pp, class _Rp, class _MP, class _Dp, _Dp>
446        friend class _LIBCPP_TEMPLATE_VIS __deque_iterator;
447
448    template <class _RAIter,
449              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
450    friend
451    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
452    copy(_RAIter __f,
453         _RAIter __l,
454         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
455         typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*);
456
457    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
458              class _OutputIterator>
459    friend
460    _OutputIterator
461    copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
462         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
463         _OutputIterator __r);
464
465    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
466              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
467    friend
468    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
469    copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
470         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
471         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
472
473    template <class _RAIter,
474              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
475    friend
476    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
477    copy_backward(_RAIter __f,
478                  _RAIter __l,
479                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
480                  typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*);
481
482    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
483              class _OutputIterator>
484    friend
485    _OutputIterator
486    copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
487                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
488                  _OutputIterator __r);
489
490    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
491              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
492    friend
493    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
494    copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
495                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
496                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
497
498    template <class _RAIter,
499              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
500    friend
501    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
502    move(_RAIter __f,
503         _RAIter __l,
504         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
505         typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*);
506
507    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
508              class _OutputIterator>
509    friend
510    _OutputIterator
511    move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
512         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
513         _OutputIterator __r);
514
515    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
516              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
517    friend
518    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
519    move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
520         __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
521         __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
522
523    template <class _RAIter,
524              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
525    friend
526    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
527    move_backward(_RAIter __f,
528                  _RAIter __l,
529                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
530                  typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*);
531
532    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
533              class _OutputIterator>
534    friend
535    _OutputIterator
536    move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
537                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
538                  _OutputIterator __r);
539
540    template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
541              class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
542    friend
543    __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
544    move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
545                  __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
546                  __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r);
547};
548
549template <class _ValueType, class _Pointer, class _Reference, class _MapPointer,
550          class _DiffType, _DiffType _BlockSize>
551const _DiffType __deque_iterator<_ValueType, _Pointer, _Reference, _MapPointer,
552                                 _DiffType, _BlockSize>::__block_size =
553    __deque_block_size<_ValueType, _DiffType>::value;
554
555// copy
556
557template <class _RAIter,
558          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
559__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
560copy(_RAIter __f,
561     _RAIter __l,
562     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
563     typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
564{
565    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
566    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
567    const difference_type __block_size = __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::__block_size;
568    while (__f != __l)
569    {
570        pointer __rb = __r.__ptr_;
571        pointer __re = *__r.__m_iter_ + __block_size;
572        difference_type __bs = __re - __rb;
573        difference_type __n = __l - __f;
574        _RAIter __m = __l;
575        if (__n > __bs)
576        {
577            __n = __bs;
578            __m = __f + __n;
579        }
580        _VSTD::copy(__f, __m, __rb);
581        __f = __m;
582        __r += __n;
583    }
584    return __r;
585}
586
587template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
588          class _OutputIterator>
589_OutputIterator
590copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
591     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
592     _OutputIterator __r)
593{
594    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
595    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
596    const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
597    difference_type __n = __l - __f;
598    while (__n > 0)
599    {
600        pointer __fb = __f.__ptr_;
601        pointer __fe = *__f.__m_iter_ + __block_size;
602        difference_type __bs = __fe - __fb;
603        if (__bs > __n)
604        {
605            __bs = __n;
606            __fe = __fb + __bs;
607        }
608        __r = _VSTD::copy(__fb, __fe, __r);
609        __n -= __bs;
610        __f += __bs;
611    }
612    return __r;
613}
614
615template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
616          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
617__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
618copy(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
619     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
620     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
621{
622    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
623    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
624    const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
625    difference_type __n = __l - __f;
626    while (__n > 0)
627    {
628        pointer __fb = __f.__ptr_;
629        pointer __fe = *__f.__m_iter_ + __block_size;
630        difference_type __bs = __fe - __fb;
631        if (__bs > __n)
632        {
633            __bs = __n;
634            __fe = __fb + __bs;
635        }
636        __r = _VSTD::copy(__fb, __fe, __r);
637        __n -= __bs;
638        __f += __bs;
639    }
640    return __r;
641}
642
643// copy_backward
644
645template <class _RAIter,
646          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
647__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
648copy_backward(_RAIter __f,
649              _RAIter __l,
650              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
651              typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
652{
653    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
654    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
655    while (__f != __l)
656    {
657        __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __rp = _VSTD::prev(__r);
658        pointer __rb = *__rp.__m_iter_;
659        pointer __re = __rp.__ptr_ + 1;
660        difference_type __bs = __re - __rb;
661        difference_type __n = __l - __f;
662        _RAIter __m = __f;
663        if (__n > __bs)
664        {
665            __n = __bs;
666            __m = __l - __n;
667        }
668        _VSTD::copy_backward(__m, __l, __re);
669        __l = __m;
670        __r -= __n;
671    }
672    return __r;
673}
674
675template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
676          class _OutputIterator>
677_OutputIterator
678copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
679              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
680              _OutputIterator __r)
681{
682    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
683    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
684    difference_type __n = __l - __f;
685    while (__n > 0)
686    {
687        --__l;
688        pointer __lb = *__l.__m_iter_;
689        pointer __le = __l.__ptr_ + 1;
690        difference_type __bs = __le - __lb;
691        if (__bs > __n)
692        {
693            __bs = __n;
694            __lb = __le - __bs;
695        }
696        __r = _VSTD::copy_backward(__lb, __le, __r);
697        __n -= __bs;
698        __l -= __bs - 1;
699    }
700    return __r;
701}
702
703template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
704          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
705__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
706copy_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
707              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
708              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
709{
710    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
711    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
712    difference_type __n = __l - __f;
713    while (__n > 0)
714    {
715        --__l;
716        pointer __lb = *__l.__m_iter_;
717        pointer __le = __l.__ptr_ + 1;
718        difference_type __bs = __le - __lb;
719        if (__bs > __n)
720        {
721            __bs = __n;
722            __lb = __le - __bs;
723        }
724        __r = _VSTD::copy_backward(__lb, __le, __r);
725        __n -= __bs;
726        __l -= __bs - 1;
727    }
728    return __r;
729}
730
731// move
732
733template <class _RAIter,
734          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
735__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
736move(_RAIter __f,
737     _RAIter __l,
738     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
739     typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
740{
741    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
742    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
743    const difference_type __block_size = __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::__block_size;
744    while (__f != __l)
745    {
746        pointer __rb = __r.__ptr_;
747        pointer __re = *__r.__m_iter_ + __block_size;
748        difference_type __bs = __re - __rb;
749        difference_type __n = __l - __f;
750        _RAIter __m = __l;
751        if (__n > __bs)
752        {
753            __n = __bs;
754            __m = __f + __n;
755        }
756        _VSTD::move(__f, __m, __rb);
757        __f = __m;
758        __r += __n;
759    }
760    return __r;
761}
762
763template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
764          class _OutputIterator>
765_OutputIterator
766move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
767     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
768     _OutputIterator __r)
769{
770    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
771    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
772    const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
773    difference_type __n = __l - __f;
774    while (__n > 0)
775    {
776        pointer __fb = __f.__ptr_;
777        pointer __fe = *__f.__m_iter_ + __block_size;
778        difference_type __bs = __fe - __fb;
779        if (__bs > __n)
780        {
781            __bs = __n;
782            __fe = __fb + __bs;
783        }
784        __r = _VSTD::move(__fb, __fe, __r);
785        __n -= __bs;
786        __f += __bs;
787    }
788    return __r;
789}
790
791template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
792          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
793__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
794move(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
795     __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
796     __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
797{
798    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
799    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
800    const difference_type __block_size = __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::__block_size;
801    difference_type __n = __l - __f;
802    while (__n > 0)
803    {
804        pointer __fb = __f.__ptr_;
805        pointer __fe = *__f.__m_iter_ + __block_size;
806        difference_type __bs = __fe - __fb;
807        if (__bs > __n)
808        {
809            __bs = __n;
810            __fe = __fb + __bs;
811        }
812        __r = _VSTD::move(__fb, __fe, __r);
813        __n -= __bs;
814        __f += __bs;
815    }
816    return __r;
817}
818
819// move_backward
820
821template <class _RAIter,
822          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
823__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
824move_backward(_RAIter __f,
825              _RAIter __l,
826              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r,
827              typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
828{
829    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::difference_type difference_type;
830    typedef typename __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>::pointer pointer;
831    while (__f != __l)
832    {
833        __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __rp = _VSTD::prev(__r);
834        pointer __rb = *__rp.__m_iter_;
835        pointer __re = __rp.__ptr_ + 1;
836        difference_type __bs = __re - __rb;
837        difference_type __n = __l - __f;
838        _RAIter __m = __f;
839        if (__n > __bs)
840        {
841            __n = __bs;
842            __m = __l - __n;
843        }
844        _VSTD::move_backward(__m, __l, __re);
845        __l = __m;
846        __r -= __n;
847    }
848    return __r;
849}
850
851template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
852          class _OutputIterator>
853_OutputIterator
854move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
855              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
856              _OutputIterator __r)
857{
858    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
859    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
860    difference_type __n = __l - __f;
861    while (__n > 0)
862    {
863        --__l;
864        pointer __lb = *__l.__m_iter_;
865        pointer __le = __l.__ptr_ + 1;
866        difference_type __bs = __le - __lb;
867        if (__bs > __n)
868        {
869            __bs = __n;
870            __lb = __le - __bs;
871        }
872        __r = _VSTD::move_backward(__lb, __le, __r);
873        __n -= __bs;
874        __l -= __bs - 1;
875    }
876    return __r;
877}
878
879template <class _V1, class _P1, class _R1, class _M1, class _D1, _D1 _B1,
880          class _V2, class _P2, class _R2, class _M2, class _D2, _D2 _B2>
881__deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2>
882move_backward(__deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __f,
883              __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1> __l,
884              __deque_iterator<_V2, _P2, _R2, _M2, _D2, _B2> __r)
885{
886    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::difference_type difference_type;
887    typedef typename __deque_iterator<_V1, _P1, _R1, _M1, _D1, _B1>::pointer pointer;
888    difference_type __n = __l - __f;
889    while (__n > 0)
890    {
891        --__l;
892        pointer __lb = *__l.__m_iter_;
893        pointer __le = __l.__ptr_ + 1;
894        difference_type __bs = __le - __lb;
895        if (__bs > __n)
896        {
897            __bs = __n;
898            __lb = __le - __bs;
899        }
900        __r = _VSTD::move_backward(__lb, __le, __r);
901        __n -= __bs;
902        __l -= __bs - 1;
903    }
904    return __r;
905}
906
907template <bool>
908class __deque_base_common
909{
910protected:
911    _LIBCPP_NORETURN void __throw_length_error() const;
912    _LIBCPP_NORETURN void __throw_out_of_range() const;
913};
914
915template <bool __b>
916void
917__deque_base_common<__b>::__throw_length_error() const
918{
919    _VSTD::__throw_length_error("deque");
920}
921
922template <bool __b>
923void
924__deque_base_common<__b>::__throw_out_of_range() const
925{
926    _VSTD::__throw_out_of_range("deque");
927}
928
929template <class _Tp, class _Allocator>
930class __deque_base
931    : protected __deque_base_common<true>
932{
933    __deque_base(const __deque_base& __c);
934    __deque_base& operator=(const __deque_base& __c);
935public:
936    typedef _Allocator                               allocator_type;
937    typedef allocator_traits<allocator_type>         __alloc_traits;
938    typedef typename __alloc_traits::size_type       size_type;
939
940    typedef _Tp                                      value_type;
941    typedef value_type&                              reference;
942    typedef const value_type&                        const_reference;
943    typedef typename __alloc_traits::difference_type difference_type;
944    typedef typename __alloc_traits::pointer         pointer;
945    typedef typename __alloc_traits::const_pointer   const_pointer;
946
947    static const difference_type __block_size;
948
949    typedef typename __rebind_alloc_helper<__alloc_traits, pointer>::type __pointer_allocator;
950    typedef allocator_traits<__pointer_allocator>        __map_traits;
951    typedef typename __map_traits::pointer               __map_pointer;
952    typedef typename __rebind_alloc_helper<__alloc_traits, const_pointer>::type __const_pointer_allocator;
953    typedef typename allocator_traits<__const_pointer_allocator>::const_pointer __map_const_pointer;
954    typedef __split_buffer<pointer, __pointer_allocator> __map;
955
956    typedef __deque_iterator<value_type, pointer, reference, __map_pointer,
957                             difference_type>    iterator;
958    typedef __deque_iterator<value_type, const_pointer, const_reference, __map_const_pointer,
959                             difference_type>    const_iterator;
960
961    struct __deque_block_range {
962      explicit __deque_block_range(pointer __b, pointer __e) _NOEXCEPT : __begin_(__b), __end_(__e) {}
963      const pointer __begin_;
964      const pointer __end_;
965    };
966
967    struct __deque_range {
968      iterator __pos_;
969      const iterator __end_;
970
971      __deque_range(iterator __pos, iterator __e) _NOEXCEPT
972        : __pos_(__pos), __end_(__e) {}
973
974      explicit operator bool() const _NOEXCEPT {
975        return __pos_ != __end_;
976      }
977
978      __deque_range begin() const {
979        return *this;
980      }
981
982      __deque_range end() const {
983        return __deque_range(__end_, __end_);
984      }
985      __deque_block_range operator*() const _NOEXCEPT {
986         if (__pos_.__m_iter_ == __end_.__m_iter_) {
987          return __deque_block_range(__pos_.__ptr_, __end_.__ptr_);
988        }
989        return __deque_block_range(__pos_.__ptr_, *__pos_.__m_iter_ + __block_size);
990      }
991
992      __deque_range& operator++() _NOEXCEPT {
993        if (__pos_.__m_iter_ == __end_.__m_iter_) {
994          __pos_ = __end_;
995        } else {
996          ++__pos_.__m_iter_;
997          __pos_.__ptr_ = *__pos_.__m_iter_;
998        }
999        return *this;
1000      }
1001
1002
1003      friend bool operator==(__deque_range const& __lhs, __deque_range const& __rhs) {
1004        return __lhs.__pos_ == __rhs.__pos_;
1005      }
1006      friend bool operator!=(__deque_range const& __lhs, __deque_range const& __rhs) {
1007        return !(__lhs == __rhs);
1008      }
1009    };
1010
1011
1012
1013    struct _ConstructTransaction {
1014      _ConstructTransaction(__deque_base* __db, __deque_block_range& __r)
1015        : __pos_(__r.__begin_), __end_(__r.__end_), __begin_(__r.__begin_), __base_(__db) {}
1016
1017
1018      ~_ConstructTransaction() {
1019        __base_->size() += (__pos_ - __begin_);
1020      }
1021
1022      pointer __pos_;
1023      const pointer __end_;
1024    private:
1025      const pointer __begin_;
1026      __deque_base * const __base_;
1027    };
1028
1029protected:
1030    __map __map_;
1031    size_type __start_;
1032    __compressed_pair<size_type, allocator_type> __size_;
1033
1034    iterator       begin() _NOEXCEPT;
1035    const_iterator begin() const _NOEXCEPT;
1036    iterator       end() _NOEXCEPT;
1037    const_iterator end() const _NOEXCEPT;
1038
1039    _LIBCPP_INLINE_VISIBILITY size_type&            size()          {return __size_.first();}
1040    _LIBCPP_INLINE_VISIBILITY
1041    const size_type& size() const _NOEXCEPT {return __size_.first();}
1042    _LIBCPP_INLINE_VISIBILITY allocator_type&       __alloc()       {return __size_.second();}
1043    _LIBCPP_INLINE_VISIBILITY
1044    const allocator_type& __alloc() const _NOEXCEPT {return __size_.second();}
1045
1046    _LIBCPP_INLINE_VISIBILITY
1047    __deque_base()
1048        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
1049    _LIBCPP_INLINE_VISIBILITY
1050    explicit __deque_base(const allocator_type& __a);
1051public:
1052    ~__deque_base();
1053
1054#ifndef _LIBCPP_CXX03_LANG
1055    __deque_base(__deque_base&& __c)
1056        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
1057    __deque_base(__deque_base&& __c, const allocator_type& __a);
1058#endif  // _LIBCPP_CXX03_LANG
1059
1060    void swap(__deque_base& __c)
1061#if _LIBCPP_STD_VER >= 14
1062        _NOEXCEPT;
1063#else
1064        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1065                    __is_nothrow_swappable<allocator_type>::value);
1066#endif
1067protected:
1068    void clear() _NOEXCEPT;
1069
1070    bool __invariants() const;
1071
1072    _LIBCPP_INLINE_VISIBILITY
1073    void __move_assign(__deque_base& __c)
1074        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
1075                   is_nothrow_move_assignable<allocator_type>::value)
1076    {
1077        __map_ = _VSTD::move(__c.__map_);
1078        __start_ = __c.__start_;
1079        size() = __c.size();
1080        __move_assign_alloc(__c);
1081        __c.__start_ = __c.size() = 0;
1082    }
1083
1084    _LIBCPP_INLINE_VISIBILITY
1085    void __move_assign_alloc(__deque_base& __c)
1086        _NOEXCEPT_(!__alloc_traits::propagate_on_container_move_assignment::value ||
1087                   is_nothrow_move_assignable<allocator_type>::value)
1088        {__move_assign_alloc(__c, integral_constant<bool,
1089                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1090
1091private:
1092    _LIBCPP_INLINE_VISIBILITY
1093    void __move_assign_alloc(__deque_base& __c, true_type)
1094        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1095        {
1096            __alloc() = _VSTD::move(__c.__alloc());
1097        }
1098
1099    _LIBCPP_INLINE_VISIBILITY
1100    void __move_assign_alloc(__deque_base&, false_type) _NOEXCEPT
1101        {}
1102};
1103
1104template <class _Tp, class _Allocator>
1105const typename __deque_base<_Tp, _Allocator>::difference_type
1106    __deque_base<_Tp, _Allocator>::__block_size =
1107        __deque_block_size<value_type, difference_type>::value;
1108
1109template <class _Tp, class _Allocator>
1110bool
1111__deque_base<_Tp, _Allocator>::__invariants() const
1112{
1113    if (!__map_.__invariants())
1114        return false;
1115    if (__map_.size() >= size_type(-1) / __block_size)
1116        return false;
1117    for (typename __map::const_iterator __i = __map_.begin(), __e = __map_.end();
1118         __i != __e; ++__i)
1119        if (*__i == nullptr)
1120            return false;
1121    if (__map_.size() != 0)
1122    {
1123        if (size() >= __map_.size() * __block_size)
1124            return false;
1125        if (__start_ >= __map_.size() * __block_size - size())
1126            return false;
1127    }
1128    else
1129    {
1130        if (size() != 0)
1131            return false;
1132        if (__start_ != 0)
1133            return false;
1134    }
1135    return true;
1136}
1137
1138template <class _Tp, class _Allocator>
1139typename __deque_base<_Tp, _Allocator>::iterator
1140__deque_base<_Tp, _Allocator>::begin() _NOEXCEPT
1141{
1142    __map_pointer __mp = __map_.begin() + __start_ / __block_size;
1143    return iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
1144}
1145
1146template <class _Tp, class _Allocator>
1147typename __deque_base<_Tp, _Allocator>::const_iterator
1148__deque_base<_Tp, _Allocator>::begin() const _NOEXCEPT
1149{
1150    __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __start_ / __block_size);
1151    return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __start_ % __block_size);
1152}
1153
1154template <class _Tp, class _Allocator>
1155typename __deque_base<_Tp, _Allocator>::iterator
1156__deque_base<_Tp, _Allocator>::end() _NOEXCEPT
1157{
1158    size_type __p = size() + __start_;
1159    __map_pointer __mp = __map_.begin() + __p / __block_size;
1160    return iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
1161}
1162
1163template <class _Tp, class _Allocator>
1164typename __deque_base<_Tp, _Allocator>::const_iterator
1165__deque_base<_Tp, _Allocator>::end() const _NOEXCEPT
1166{
1167    size_type __p = size() + __start_;
1168    __map_const_pointer __mp = static_cast<__map_const_pointer>(__map_.begin() + __p / __block_size);
1169    return const_iterator(__mp, __map_.empty() ? 0 : *__mp + __p % __block_size);
1170}
1171
1172template <class _Tp, class _Allocator>
1173inline
1174__deque_base<_Tp, _Allocator>::__deque_base()
1175    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1176    : __start_(0), __size_(0, __default_init_tag()) {}
1177
1178template <class _Tp, class _Allocator>
1179inline
1180__deque_base<_Tp, _Allocator>::__deque_base(const allocator_type& __a)
1181    : __map_(__pointer_allocator(__a)), __start_(0), __size_(0, __a) {}
1182
1183template <class _Tp, class _Allocator>
1184__deque_base<_Tp, _Allocator>::~__deque_base()
1185{
1186    clear();
1187    typename __map::iterator __i = __map_.begin();
1188    typename __map::iterator __e = __map_.end();
1189    for (; __i != __e; ++__i)
1190        __alloc_traits::deallocate(__alloc(), *__i, __block_size);
1191}
1192
1193#ifndef _LIBCPP_CXX03_LANG
1194
1195template <class _Tp, class _Allocator>
1196__deque_base<_Tp, _Allocator>::__deque_base(__deque_base&& __c)
1197    _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1198    : __map_(_VSTD::move(__c.__map_)),
1199      __start_(_VSTD::move(__c.__start_)),
1200      __size_(_VSTD::move(__c.__size_))
1201{
1202    __c.__start_ = 0;
1203    __c.size() = 0;
1204}
1205
1206template <class _Tp, class _Allocator>
1207__deque_base<_Tp, _Allocator>::__deque_base(__deque_base&& __c, const allocator_type& __a)
1208    : __map_(_VSTD::move(__c.__map_), __pointer_allocator(__a)),
1209      __start_(_VSTD::move(__c.__start_)),
1210      __size_(_VSTD::move(__c.size()), __a)
1211{
1212    if (__a == __c.__alloc())
1213    {
1214        __c.__start_ = 0;
1215        __c.size() = 0;
1216    }
1217    else
1218    {
1219        __map_.clear();
1220        __start_ = 0;
1221        size() = 0;
1222    }
1223}
1224
1225#endif  // _LIBCPP_CXX03_LANG
1226
1227template <class _Tp, class _Allocator>
1228void
1229__deque_base<_Tp, _Allocator>::swap(__deque_base& __c)
1230#if _LIBCPP_STD_VER >= 14
1231        _NOEXCEPT
1232#else
1233        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1234                    __is_nothrow_swappable<allocator_type>::value)
1235#endif
1236{
1237    __map_.swap(__c.__map_);
1238    _VSTD::swap(__start_, __c.__start_);
1239    _VSTD::swap(size(), __c.size());
1240    __swap_allocator(__alloc(), __c.__alloc());
1241}
1242
1243template <class _Tp, class _Allocator>
1244void
1245__deque_base<_Tp, _Allocator>::clear() _NOEXCEPT
1246{
1247    allocator_type& __a = __alloc();
1248    for (iterator __i = begin(), __e = end(); __i != __e; ++__i)
1249        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
1250    size() = 0;
1251    while (__map_.size() > 2)
1252    {
1253        __alloc_traits::deallocate(__a, __map_.front(), __block_size);
1254        __map_.pop_front();
1255    }
1256    switch (__map_.size())
1257    {
1258    case 1:
1259        __start_ = __block_size / 2;
1260        break;
1261    case 2:
1262        __start_ = __block_size;
1263        break;
1264    }
1265}
1266
1267template <class _Tp, class _Allocator /*= allocator<_Tp>*/>
1268class _LIBCPP_TEMPLATE_VIS deque
1269    : private __deque_base<_Tp, _Allocator>
1270{
1271public:
1272    // types:
1273
1274    typedef _Tp value_type;
1275    typedef _Allocator allocator_type;
1276
1277    static_assert((is_same<typename allocator_type::value_type, value_type>::value),
1278                  "Allocator::value_type must be same type as value_type");
1279
1280    typedef __deque_base<value_type, allocator_type> __base;
1281
1282    typedef typename __base::__alloc_traits        __alloc_traits;
1283    typedef typename __base::reference             reference;
1284    typedef typename __base::const_reference       const_reference;
1285    typedef typename __base::iterator              iterator;
1286    typedef typename __base::const_iterator        const_iterator;
1287    typedef typename __base::size_type             size_type;
1288    typedef typename __base::difference_type       difference_type;
1289
1290    typedef typename __base::pointer               pointer;
1291    typedef typename __base::const_pointer         const_pointer;
1292    typedef _VSTD::reverse_iterator<iterator>       reverse_iterator;
1293    typedef _VSTD::reverse_iterator<const_iterator> const_reverse_iterator;
1294
1295    using typename __base::__deque_range;
1296    using typename __base::__deque_block_range;
1297    using typename __base::_ConstructTransaction;
1298
1299    // construct/copy/destroy:
1300    _LIBCPP_INLINE_VISIBILITY
1301    deque()
1302        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1303        {}
1304    _LIBCPP_INLINE_VISIBILITY explicit deque(const allocator_type& __a) : __base(__a) {}
1305    explicit deque(size_type __n);
1306#if _LIBCPP_STD_VER > 11
1307    explicit deque(size_type __n, const _Allocator& __a);
1308#endif
1309    deque(size_type __n, const value_type& __v);
1310    deque(size_type __n, const value_type& __v, const allocator_type& __a);
1311    template <class _InputIter>
1312        deque(_InputIter __f, _InputIter __l,
1313              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0);
1314    template <class _InputIter>
1315        deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
1316              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type* = 0);
1317    deque(const deque& __c);
1318    deque(const deque& __c, const allocator_type& __a);
1319
1320    deque& operator=(const deque& __c);
1321
1322#ifndef _LIBCPP_CXX03_LANG
1323    deque(initializer_list<value_type> __il);
1324    deque(initializer_list<value_type> __il, const allocator_type& __a);
1325
1326    _LIBCPP_INLINE_VISIBILITY
1327    deque& operator=(initializer_list<value_type> __il) {assign(__il); return *this;}
1328
1329    _LIBCPP_INLINE_VISIBILITY
1330    deque(deque&& __c) _NOEXCEPT_(is_nothrow_move_constructible<__base>::value);
1331    _LIBCPP_INLINE_VISIBILITY
1332    deque(deque&& __c, const allocator_type& __a);
1333    _LIBCPP_INLINE_VISIBILITY
1334    deque& operator=(deque&& __c)
1335        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
1336                   is_nothrow_move_assignable<allocator_type>::value);
1337
1338    _LIBCPP_INLINE_VISIBILITY
1339    void assign(initializer_list<value_type> __il) {assign(__il.begin(), __il.end());}
1340#endif  // _LIBCPP_CXX03_LANG
1341
1342    template <class _InputIter>
1343        void assign(_InputIter __f, _InputIter __l,
1344                    typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
1345                                      !__is_cpp17_random_access_iterator<_InputIter>::value>::type* = 0);
1346    template <class _RAIter>
1347        void assign(_RAIter __f, _RAIter __l,
1348                    typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type* = 0);
1349    void assign(size_type __n, const value_type& __v);
1350
1351    _LIBCPP_INLINE_VISIBILITY
1352    allocator_type get_allocator() const _NOEXCEPT;
1353
1354    // iterators:
1355
1356    _LIBCPP_INLINE_VISIBILITY
1357    iterator       begin() _NOEXCEPT       {return __base::begin();}
1358    _LIBCPP_INLINE_VISIBILITY
1359    const_iterator begin() const _NOEXCEPT {return __base::begin();}
1360    _LIBCPP_INLINE_VISIBILITY
1361    iterator       end() _NOEXCEPT         {return __base::end();}
1362    _LIBCPP_INLINE_VISIBILITY
1363    const_iterator end()   const _NOEXCEPT {return __base::end();}
1364
1365    _LIBCPP_INLINE_VISIBILITY
1366    reverse_iterator       rbegin() _NOEXCEPT
1367        {return       reverse_iterator(__base::end());}
1368    _LIBCPP_INLINE_VISIBILITY
1369    const_reverse_iterator rbegin() const _NOEXCEPT
1370        {return const_reverse_iterator(__base::end());}
1371    _LIBCPP_INLINE_VISIBILITY
1372    reverse_iterator       rend() _NOEXCEPT
1373        {return       reverse_iterator(__base::begin());}
1374    _LIBCPP_INLINE_VISIBILITY
1375    const_reverse_iterator rend()   const _NOEXCEPT
1376        {return const_reverse_iterator(__base::begin());}
1377
1378    _LIBCPP_INLINE_VISIBILITY
1379    const_iterator         cbegin()  const _NOEXCEPT
1380        {return __base::begin();}
1381    _LIBCPP_INLINE_VISIBILITY
1382    const_iterator         cend()    const _NOEXCEPT
1383        {return __base::end();}
1384    _LIBCPP_INLINE_VISIBILITY
1385    const_reverse_iterator crbegin() const _NOEXCEPT
1386        {return const_reverse_iterator(__base::end());}
1387    _LIBCPP_INLINE_VISIBILITY
1388    const_reverse_iterator crend()   const _NOEXCEPT
1389        {return const_reverse_iterator(__base::begin());}
1390
1391    // capacity:
1392    _LIBCPP_INLINE_VISIBILITY
1393    size_type size() const _NOEXCEPT {return __base::size();}
1394    _LIBCPP_INLINE_VISIBILITY
1395    size_type max_size() const _NOEXCEPT
1396        {return std::min<size_type>(
1397            __alloc_traits::max_size(__base::__alloc()),
1398            numeric_limits<difference_type>::max());}
1399    void resize(size_type __n);
1400    void resize(size_type __n, const value_type& __v);
1401    void shrink_to_fit() _NOEXCEPT;
1402    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
1403    bool empty() const _NOEXCEPT {return __base::size() == 0;}
1404
1405    // element access:
1406    _LIBCPP_INLINE_VISIBILITY
1407    reference operator[](size_type __i) _NOEXCEPT;
1408    _LIBCPP_INLINE_VISIBILITY
1409    const_reference operator[](size_type __i) const _NOEXCEPT;
1410    _LIBCPP_INLINE_VISIBILITY
1411    reference at(size_type __i);
1412    _LIBCPP_INLINE_VISIBILITY
1413    const_reference at(size_type __i) const;
1414    _LIBCPP_INLINE_VISIBILITY
1415    reference front() _NOEXCEPT;
1416    _LIBCPP_INLINE_VISIBILITY
1417    const_reference front() const _NOEXCEPT;
1418    _LIBCPP_INLINE_VISIBILITY
1419    reference back() _NOEXCEPT;
1420    _LIBCPP_INLINE_VISIBILITY
1421    const_reference back() const _NOEXCEPT;
1422
1423    // 23.2.2.3 modifiers:
1424    void push_front(const value_type& __v);
1425    void push_back(const value_type& __v);
1426#ifndef _LIBCPP_CXX03_LANG
1427#if _LIBCPP_STD_VER > 14
1428    template <class... _Args> reference emplace_front(_Args&&... __args);
1429    template <class... _Args> reference emplace_back (_Args&&... __args);
1430#else
1431    template <class... _Args> void      emplace_front(_Args&&... __args);
1432    template <class... _Args> void      emplace_back (_Args&&... __args);
1433#endif
1434    template <class... _Args> iterator emplace(const_iterator __p, _Args&&... __args);
1435
1436    void push_front(value_type&& __v);
1437    void push_back(value_type&& __v);
1438    iterator insert(const_iterator __p, value_type&& __v);
1439
1440    _LIBCPP_INLINE_VISIBILITY
1441    iterator insert(const_iterator __p, initializer_list<value_type> __il)
1442        {return insert(__p, __il.begin(), __il.end());}
1443#endif  // _LIBCPP_CXX03_LANG
1444    iterator insert(const_iterator __p, const value_type& __v);
1445    iterator insert(const_iterator __p, size_type __n, const value_type& __v);
1446    template <class _InputIter>
1447        iterator insert(const_iterator __p, _InputIter __f, _InputIter __l,
1448                         typename enable_if<__is_cpp17_input_iterator<_InputIter>::value
1449                                         &&!__is_cpp17_forward_iterator<_InputIter>::value>::type* = 0);
1450    template <class _ForwardIterator>
1451        iterator insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
1452                               typename enable_if<__is_cpp17_forward_iterator<_ForwardIterator>::value
1453                                         &&!__is_cpp17_bidirectional_iterator<_ForwardIterator>::value>::type* = 0);
1454    template <class _BiIter>
1455        iterator insert(const_iterator __p, _BiIter __f, _BiIter __l,
1456                         typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type* = 0);
1457
1458    void pop_front();
1459    void pop_back();
1460    iterator erase(const_iterator __p);
1461    iterator erase(const_iterator __f, const_iterator __l);
1462
1463    _LIBCPP_INLINE_VISIBILITY
1464    void swap(deque& __c)
1465#if _LIBCPP_STD_VER >= 14
1466        _NOEXCEPT;
1467#else
1468        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1469                   __is_nothrow_swappable<allocator_type>::value);
1470#endif
1471    _LIBCPP_INLINE_VISIBILITY
1472    void clear() _NOEXCEPT;
1473
1474    _LIBCPP_INLINE_VISIBILITY
1475    bool __invariants() const {return __base::__invariants();}
1476
1477    typedef typename __base::__map_const_pointer __map_const_pointer;
1478
1479    _LIBCPP_INLINE_VISIBILITY
1480    static size_type __recommend_blocks(size_type __n)
1481    {
1482        return __n / __base::__block_size + (__n % __base::__block_size != 0);
1483    }
1484    _LIBCPP_INLINE_VISIBILITY
1485    size_type __capacity() const
1486    {
1487        return __base::__map_.size() == 0 ? 0 : __base::__map_.size() * __base::__block_size - 1;
1488    }
1489    _LIBCPP_INLINE_VISIBILITY
1490    size_type __block_count() const
1491    {
1492        return __base::__map_.size();
1493    }
1494
1495    _LIBCPP_INLINE_VISIBILITY
1496    size_type __front_spare() const
1497    {
1498        return __base::__start_;
1499    }
1500    _LIBCPP_INLINE_VISIBILITY
1501    size_type __front_spare_blocks() const {
1502      return __front_spare() / __base::__block_size;
1503    }
1504    _LIBCPP_INLINE_VISIBILITY
1505    size_type __back_spare() const
1506    {
1507        return __capacity() - (__base::__start_ + __base::size());
1508    }
1509    _LIBCPP_INLINE_VISIBILITY
1510    size_type __back_spare_blocks() const {
1511      return __back_spare() / __base::__block_size;
1512    }
1513
1514 private:
1515    _LIBCPP_INLINE_VISIBILITY
1516    bool __maybe_remove_front_spare(bool __keep_one = true) {
1517      if (__front_spare_blocks() >= 2 || (!__keep_one && __front_spare_blocks())) {
1518        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.front(),
1519                                   __base::__block_size);
1520        __base::__map_.pop_front();
1521        __base::__start_ -= __base::__block_size;
1522        return true;
1523      }
1524      return false;
1525    }
1526
1527    _LIBCPP_INLINE_VISIBILITY
1528    bool __maybe_remove_back_spare(bool __keep_one = true) {
1529      if (__back_spare_blocks() >= 2 || (!__keep_one && __back_spare_blocks())) {
1530        __alloc_traits::deallocate(__base::__alloc(), __base::__map_.back(),
1531                                   __base::__block_size);
1532        __base::__map_.pop_back();
1533        return true;
1534      }
1535      return false;
1536    }
1537
1538    template <class _InpIter>
1539        void __append(_InpIter __f, _InpIter __l,
1540                 typename enable_if<__is_cpp17_input_iterator<_InpIter>::value &&
1541                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type* = 0);
1542    template <class _ForIter>
1543        void __append(_ForIter __f, _ForIter __l,
1544                      typename enable_if<__is_cpp17_forward_iterator<_ForIter>::value>::type* = 0);
1545    void __append(size_type __n);
1546    void __append(size_type __n, const value_type& __v);
1547    void __erase_to_end(const_iterator __f);
1548    void __add_front_capacity();
1549    void __add_front_capacity(size_type __n);
1550    void __add_back_capacity();
1551    void __add_back_capacity(size_type __n);
1552    iterator __move_and_check(iterator __f, iterator __l, iterator __r,
1553                              const_pointer& __vt);
1554    iterator __move_backward_and_check(iterator __f, iterator __l, iterator __r,
1555                                       const_pointer& __vt);
1556    void __move_construct_and_check(iterator __f, iterator __l,
1557                                    iterator __r, const_pointer& __vt);
1558    void __move_construct_backward_and_check(iterator __f, iterator __l,
1559                                             iterator __r, const_pointer& __vt);
1560
1561    _LIBCPP_INLINE_VISIBILITY
1562    void __copy_assign_alloc(const deque& __c)
1563        {__copy_assign_alloc(__c, integral_constant<bool,
1564                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1565
1566    _LIBCPP_INLINE_VISIBILITY
1567    void __copy_assign_alloc(const deque& __c, true_type)
1568        {
1569            if (__base::__alloc() != __c.__alloc())
1570            {
1571                clear();
1572                shrink_to_fit();
1573            }
1574            __base::__alloc() = __c.__alloc();
1575            __base::__map_.__alloc() = __c.__map_.__alloc();
1576        }
1577
1578    _LIBCPP_INLINE_VISIBILITY
1579    void __copy_assign_alloc(const deque&, false_type)
1580        {}
1581
1582    void __move_assign(deque& __c, true_type)
1583        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1584    void __move_assign(deque& __c, false_type);
1585};
1586
1587#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
1588template<class _InputIterator,
1589         class _Alloc = typename std::allocator<typename iterator_traits<_InputIterator>::value_type>,
1590         class = typename enable_if<__is_allocator<_Alloc>::value, void>::type
1591         >
1592deque(_InputIterator, _InputIterator)
1593  -> deque<typename iterator_traits<_InputIterator>::value_type, _Alloc>;
1594
1595template<class _InputIterator,
1596         class _Alloc,
1597         class = typename enable_if<__is_allocator<_Alloc>::value, void>::type
1598         >
1599deque(_InputIterator, _InputIterator, _Alloc)
1600  -> deque<typename iterator_traits<_InputIterator>::value_type, _Alloc>;
1601#endif
1602
1603
1604template <class _Tp, class _Allocator>
1605deque<_Tp, _Allocator>::deque(size_type __n)
1606{
1607    if (__n > 0)
1608        __append(__n);
1609}
1610
1611#if _LIBCPP_STD_VER > 11
1612template <class _Tp, class _Allocator>
1613deque<_Tp, _Allocator>::deque(size_type __n, const _Allocator& __a)
1614    : __base(__a)
1615{
1616    if (__n > 0)
1617        __append(__n);
1618}
1619#endif
1620
1621template <class _Tp, class _Allocator>
1622deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v)
1623{
1624    if (__n > 0)
1625        __append(__n, __v);
1626}
1627
1628template <class _Tp, class _Allocator>
1629deque<_Tp, _Allocator>::deque(size_type __n, const value_type& __v, const allocator_type& __a)
1630    : __base(__a)
1631{
1632    if (__n > 0)
1633        __append(__n, __v);
1634}
1635
1636template <class _Tp, class _Allocator>
1637template <class _InputIter>
1638deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l,
1639              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type*)
1640{
1641    __append(__f, __l);
1642}
1643
1644template <class _Tp, class _Allocator>
1645template <class _InputIter>
1646deque<_Tp, _Allocator>::deque(_InputIter __f, _InputIter __l, const allocator_type& __a,
1647              typename enable_if<__is_cpp17_input_iterator<_InputIter>::value>::type*)
1648    : __base(__a)
1649{
1650    __append(__f, __l);
1651}
1652
1653template <class _Tp, class _Allocator>
1654deque<_Tp, _Allocator>::deque(const deque& __c)
1655    : __base(__alloc_traits::select_on_container_copy_construction(__c.__alloc()))
1656{
1657    __append(__c.begin(), __c.end());
1658}
1659
1660template <class _Tp, class _Allocator>
1661deque<_Tp, _Allocator>::deque(const deque& __c, const allocator_type& __a)
1662    : __base(__a)
1663{
1664    __append(__c.begin(), __c.end());
1665}
1666
1667template <class _Tp, class _Allocator>
1668deque<_Tp, _Allocator>&
1669deque<_Tp, _Allocator>::operator=(const deque& __c)
1670{
1671    if (this != &__c)
1672    {
1673        __copy_assign_alloc(__c);
1674        assign(__c.begin(), __c.end());
1675    }
1676    return *this;
1677}
1678
1679#ifndef _LIBCPP_CXX03_LANG
1680
1681template <class _Tp, class _Allocator>
1682deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il)
1683{
1684    __append(__il.begin(), __il.end());
1685}
1686
1687template <class _Tp, class _Allocator>
1688deque<_Tp, _Allocator>::deque(initializer_list<value_type> __il, const allocator_type& __a)
1689    : __base(__a)
1690{
1691    __append(__il.begin(), __il.end());
1692}
1693
1694template <class _Tp, class _Allocator>
1695inline
1696deque<_Tp, _Allocator>::deque(deque&& __c)
1697    _NOEXCEPT_(is_nothrow_move_constructible<__base>::value)
1698    : __base(_VSTD::move(__c))
1699{
1700}
1701
1702template <class _Tp, class _Allocator>
1703inline
1704deque<_Tp, _Allocator>::deque(deque&& __c, const allocator_type& __a)
1705    : __base(_VSTD::move(__c), __a)
1706{
1707    if (__a != __c.__alloc())
1708    {
1709        typedef move_iterator<iterator> _Ip;
1710        assign(_Ip(__c.begin()), _Ip(__c.end()));
1711    }
1712}
1713
1714template <class _Tp, class _Allocator>
1715inline
1716deque<_Tp, _Allocator>&
1717deque<_Tp, _Allocator>::operator=(deque&& __c)
1718        _NOEXCEPT_(__alloc_traits::propagate_on_container_move_assignment::value &&
1719                   is_nothrow_move_assignable<allocator_type>::value)
1720{
1721    __move_assign(__c, integral_constant<bool,
1722          __alloc_traits::propagate_on_container_move_assignment::value>());
1723    return *this;
1724}
1725
1726template <class _Tp, class _Allocator>
1727void
1728deque<_Tp, _Allocator>::__move_assign(deque& __c, false_type)
1729{
1730    if (__base::__alloc() != __c.__alloc())
1731    {
1732        typedef move_iterator<iterator> _Ip;
1733        assign(_Ip(__c.begin()), _Ip(__c.end()));
1734    }
1735    else
1736        __move_assign(__c, true_type());
1737}
1738
1739template <class _Tp, class _Allocator>
1740void
1741deque<_Tp, _Allocator>::__move_assign(deque& __c, true_type)
1742    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1743{
1744    clear();
1745    shrink_to_fit();
1746    __base::__move_assign(__c);
1747}
1748
1749#endif  // _LIBCPP_CXX03_LANG
1750
1751template <class _Tp, class _Allocator>
1752template <class _InputIter>
1753void
1754deque<_Tp, _Allocator>::assign(_InputIter __f, _InputIter __l,
1755                               typename enable_if<__is_cpp17_input_iterator<_InputIter>::value &&
1756                                                 !__is_cpp17_random_access_iterator<_InputIter>::value>::type*)
1757{
1758    iterator __i = __base::begin();
1759    iterator __e = __base::end();
1760    for (; __f != __l && __i != __e; ++__f, (void) ++__i)
1761        *__i = *__f;
1762    if (__f != __l)
1763        __append(__f, __l);
1764    else
1765        __erase_to_end(__i);
1766}
1767
1768template <class _Tp, class _Allocator>
1769template <class _RAIter>
1770void
1771deque<_Tp, _Allocator>::assign(_RAIter __f, _RAIter __l,
1772                               typename enable_if<__is_cpp17_random_access_iterator<_RAIter>::value>::type*)
1773{
1774    if (static_cast<size_type>(__l - __f) > __base::size())
1775    {
1776        _RAIter __m = __f + __base::size();
1777        _VSTD::copy(__f, __m, __base::begin());
1778        __append(__m, __l);
1779    }
1780    else
1781        __erase_to_end(_VSTD::copy(__f, __l, __base::begin()));
1782}
1783
1784template <class _Tp, class _Allocator>
1785void
1786deque<_Tp, _Allocator>::assign(size_type __n, const value_type& __v)
1787{
1788    if (__n > __base::size())
1789    {
1790        _VSTD::fill_n(__base::begin(), __base::size(), __v);
1791        __n -= __base::size();
1792        __append(__n, __v);
1793    }
1794    else
1795        __erase_to_end(_VSTD::fill_n(__base::begin(), __n, __v));
1796}
1797
1798template <class _Tp, class _Allocator>
1799inline
1800_Allocator
1801deque<_Tp, _Allocator>::get_allocator() const _NOEXCEPT
1802{
1803    return __base::__alloc();
1804}
1805
1806template <class _Tp, class _Allocator>
1807void
1808deque<_Tp, _Allocator>::resize(size_type __n)
1809{
1810    if (__n > __base::size())
1811        __append(__n - __base::size());
1812    else if (__n < __base::size())
1813        __erase_to_end(__base::begin() + __n);
1814}
1815
1816template <class _Tp, class _Allocator>
1817void
1818deque<_Tp, _Allocator>::resize(size_type __n, const value_type& __v)
1819{
1820    if (__n > __base::size())
1821        __append(__n - __base::size(), __v);
1822    else if (__n < __base::size())
1823        __erase_to_end(__base::begin() + __n);
1824}
1825
1826template <class _Tp, class _Allocator>
1827void
1828deque<_Tp, _Allocator>::shrink_to_fit() _NOEXCEPT
1829{
1830    allocator_type& __a = __base::__alloc();
1831    if (empty())
1832    {
1833        while (__base::__map_.size() > 0)
1834        {
1835            __alloc_traits::deallocate(__a, __base::__map_.back(), __base::__block_size);
1836            __base::__map_.pop_back();
1837        }
1838        __base::__start_ = 0;
1839    }
1840    else
1841    {
1842      __maybe_remove_front_spare(/*__keep_one=*/false);
1843      __maybe_remove_back_spare(/*__keep_one=*/false);
1844    }
1845    __base::__map_.shrink_to_fit();
1846}
1847
1848template <class _Tp, class _Allocator>
1849inline
1850typename deque<_Tp, _Allocator>::reference
1851deque<_Tp, _Allocator>::operator[](size_type __i) _NOEXCEPT
1852{
1853    size_type __p = __base::__start_ + __i;
1854    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1855}
1856
1857template <class _Tp, class _Allocator>
1858inline
1859typename deque<_Tp, _Allocator>::const_reference
1860deque<_Tp, _Allocator>::operator[](size_type __i) const _NOEXCEPT
1861{
1862    size_type __p = __base::__start_ + __i;
1863    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1864}
1865
1866template <class _Tp, class _Allocator>
1867inline
1868typename deque<_Tp, _Allocator>::reference
1869deque<_Tp, _Allocator>::at(size_type __i)
1870{
1871    if (__i >= __base::size())
1872        __base::__throw_out_of_range();
1873    size_type __p = __base::__start_ + __i;
1874    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1875}
1876
1877template <class _Tp, class _Allocator>
1878inline
1879typename deque<_Tp, _Allocator>::const_reference
1880deque<_Tp, _Allocator>::at(size_type __i) const
1881{
1882    if (__i >= __base::size())
1883        __base::__throw_out_of_range();
1884    size_type __p = __base::__start_ + __i;
1885    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1886}
1887
1888template <class _Tp, class _Allocator>
1889inline
1890typename deque<_Tp, _Allocator>::reference
1891deque<_Tp, _Allocator>::front() _NOEXCEPT
1892{
1893    return *(*(__base::__map_.begin() + __base::__start_ / __base::__block_size)
1894                                      + __base::__start_ % __base::__block_size);
1895}
1896
1897template <class _Tp, class _Allocator>
1898inline
1899typename deque<_Tp, _Allocator>::const_reference
1900deque<_Tp, _Allocator>::front() const _NOEXCEPT
1901{
1902    return *(*(__base::__map_.begin() + __base::__start_ / __base::__block_size)
1903                                      + __base::__start_ % __base::__block_size);
1904}
1905
1906template <class _Tp, class _Allocator>
1907inline
1908typename deque<_Tp, _Allocator>::reference
1909deque<_Tp, _Allocator>::back() _NOEXCEPT
1910{
1911    size_type __p = __base::size() + __base::__start_ - 1;
1912    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1913}
1914
1915template <class _Tp, class _Allocator>
1916inline
1917typename deque<_Tp, _Allocator>::const_reference
1918deque<_Tp, _Allocator>::back() const _NOEXCEPT
1919{
1920    size_type __p = __base::size() + __base::__start_ - 1;
1921    return *(*(__base::__map_.begin() + __p / __base::__block_size) + __p % __base::__block_size);
1922}
1923
1924template <class _Tp, class _Allocator>
1925void
1926deque<_Tp, _Allocator>::push_back(const value_type& __v)
1927{
1928    allocator_type& __a = __base::__alloc();
1929    if (__back_spare() == 0)
1930        __add_back_capacity();
1931    // __back_spare() >= 1
1932    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), __v);
1933    ++__base::size();
1934}
1935
1936template <class _Tp, class _Allocator>
1937void
1938deque<_Tp, _Allocator>::push_front(const value_type& __v)
1939{
1940    allocator_type& __a = __base::__alloc();
1941    if (__front_spare() == 0)
1942        __add_front_capacity();
1943    // __front_spare() >= 1
1944    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), __v);
1945    --__base::__start_;
1946    ++__base::size();
1947}
1948
1949#ifndef _LIBCPP_CXX03_LANG
1950template <class _Tp, class _Allocator>
1951void
1952deque<_Tp, _Allocator>::push_back(value_type&& __v)
1953{
1954    allocator_type& __a = __base::__alloc();
1955    if (__back_spare() == 0)
1956        __add_back_capacity();
1957    // __back_spare() >= 1
1958    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::move(__v));
1959    ++__base::size();
1960}
1961
1962template <class _Tp, class _Allocator>
1963template <class... _Args>
1964#if _LIBCPP_STD_VER > 14
1965typename deque<_Tp, _Allocator>::reference
1966#else
1967void
1968#endif
1969deque<_Tp, _Allocator>::emplace_back(_Args&&... __args)
1970{
1971    allocator_type& __a = __base::__alloc();
1972    if (__back_spare() == 0)
1973        __add_back_capacity();
1974    // __back_spare() >= 1
1975    __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()),
1976                              _VSTD::forward<_Args>(__args)...);
1977    ++__base::size();
1978#if _LIBCPP_STD_VER > 14
1979    return *--__base::end();
1980#endif
1981}
1982
1983template <class _Tp, class _Allocator>
1984void
1985deque<_Tp, _Allocator>::push_front(value_type&& __v)
1986{
1987    allocator_type& __a = __base::__alloc();
1988    if (__front_spare() == 0)
1989        __add_front_capacity();
1990    // __front_spare() >= 1
1991    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::move(__v));
1992    --__base::__start_;
1993    ++__base::size();
1994}
1995
1996
1997template <class _Tp, class _Allocator>
1998template <class... _Args>
1999#if _LIBCPP_STD_VER > 14
2000typename deque<_Tp, _Allocator>::reference
2001#else
2002void
2003#endif
2004deque<_Tp, _Allocator>::emplace_front(_Args&&... __args)
2005{
2006    allocator_type& __a = __base::__alloc();
2007    if (__front_spare() == 0)
2008        __add_front_capacity();
2009    // __front_spare() >= 1
2010    __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::forward<_Args>(__args)...);
2011    --__base::__start_;
2012    ++__base::size();
2013#if _LIBCPP_STD_VER > 14
2014    return *__base::begin();
2015#endif
2016}
2017
2018template <class _Tp, class _Allocator>
2019typename deque<_Tp, _Allocator>::iterator
2020deque<_Tp, _Allocator>::insert(const_iterator __p, value_type&& __v)
2021{
2022    size_type __pos = __p - __base::begin();
2023    size_type __to_end = __base::size() - __pos;
2024    allocator_type& __a = __base::__alloc();
2025    if (__pos < __to_end)
2026    {   // insert by shifting things backward
2027        if (__front_spare() == 0)
2028            __add_front_capacity();
2029        // __front_spare() >= 1
2030        if (__pos == 0)
2031        {
2032            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::move(__v));
2033            --__base::__start_;
2034            ++__base::size();
2035        }
2036        else
2037        {
2038            iterator __b = __base::begin();
2039            iterator __bm1 = _VSTD::prev(__b);
2040            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
2041            --__base::__start_;
2042            ++__base::size();
2043            if (__pos > 1)
2044                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
2045            *__b = _VSTD::move(__v);
2046        }
2047    }
2048    else
2049    {   // insert by shifting things forward
2050        if (__back_spare() == 0)
2051            __add_back_capacity();
2052        // __back_capacity >= 1
2053        size_type __de = __base::size() - __pos;
2054        if (__de == 0)
2055        {
2056            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::move(__v));
2057            ++__base::size();
2058        }
2059        else
2060        {
2061            iterator __e = __base::end();
2062            iterator __em1 = _VSTD::prev(__e);
2063            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
2064            ++__base::size();
2065            if (__de > 1)
2066                __e = _VSTD::move_backward(__e - __de, __em1, __e);
2067            *--__e = _VSTD::move(__v);
2068        }
2069    }
2070    return __base::begin() + __pos;
2071}
2072
2073template <class _Tp, class _Allocator>
2074template <class... _Args>
2075typename deque<_Tp, _Allocator>::iterator
2076deque<_Tp, _Allocator>::emplace(const_iterator __p, _Args&&... __args)
2077{
2078    size_type __pos = __p - __base::begin();
2079    size_type __to_end = __base::size() - __pos;
2080    allocator_type& __a = __base::__alloc();
2081    if (__pos < __to_end)
2082    {   // insert by shifting things backward
2083        if (__front_spare() == 0)
2084            __add_front_capacity();
2085        // __front_spare() >= 1
2086        if (__pos == 0)
2087        {
2088            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), _VSTD::forward<_Args>(__args)...);
2089            --__base::__start_;
2090            ++__base::size();
2091        }
2092        else
2093        {
2094            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _VSTD::forward<_Args>(__args)...);
2095            iterator __b = __base::begin();
2096            iterator __bm1 = _VSTD::prev(__b);
2097            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
2098            --__base::__start_;
2099            ++__base::size();
2100            if (__pos > 1)
2101                __b = _VSTD::move(_VSTD::next(__b), __b + __pos, __b);
2102            *__b = _VSTD::move(__tmp.get());
2103        }
2104    }
2105    else
2106    {   // insert by shifting things forward
2107        if (__back_spare() == 0)
2108            __add_back_capacity();
2109        // __back_capacity >= 1
2110        size_type __de = __base::size() - __pos;
2111        if (__de == 0)
2112        {
2113            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), _VSTD::forward<_Args>(__args)...);
2114            ++__base::size();
2115        }
2116        else
2117        {
2118            __temp_value<value_type, _Allocator> __tmp(this->__alloc(), _VSTD::forward<_Args>(__args)...);
2119            iterator __e = __base::end();
2120            iterator __em1 = _VSTD::prev(__e);
2121            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
2122            ++__base::size();
2123            if (__de > 1)
2124                __e = _VSTD::move_backward(__e - __de, __em1, __e);
2125            *--__e = _VSTD::move(__tmp.get());
2126        }
2127    }
2128    return __base::begin() + __pos;
2129}
2130
2131#endif  // _LIBCPP_CXX03_LANG
2132
2133
2134template <class _Tp, class _Allocator>
2135typename deque<_Tp, _Allocator>::iterator
2136deque<_Tp, _Allocator>::insert(const_iterator __p, const value_type& __v)
2137{
2138    size_type __pos = __p - __base::begin();
2139    size_type __to_end = __base::size() - __pos;
2140    allocator_type& __a = __base::__alloc();
2141    if (__pos < __to_end)
2142    {   // insert by shifting things backward
2143        if (__front_spare() == 0)
2144            __add_front_capacity();
2145        // __front_spare() >= 1
2146        if (__pos == 0)
2147        {
2148            __alloc_traits::construct(__a, _VSTD::addressof(*--__base::begin()), __v);
2149            --__base::__start_;
2150            ++__base::size();
2151        }
2152        else
2153        {
2154            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
2155            iterator __b = __base::begin();
2156            iterator __bm1 = _VSTD::prev(__b);
2157            if (__vt == pointer_traits<const_pointer>::pointer_to(*__b))
2158                __vt = pointer_traits<const_pointer>::pointer_to(*__bm1);
2159            __alloc_traits::construct(__a, _VSTD::addressof(*__bm1), _VSTD::move(*__b));
2160            --__base::__start_;
2161            ++__base::size();
2162            if (__pos > 1)
2163                __b = __move_and_check(_VSTD::next(__b), __b + __pos, __b, __vt);
2164            *__b = *__vt;
2165        }
2166    }
2167    else
2168    {   // insert by shifting things forward
2169        if (__back_spare() == 0)
2170            __add_back_capacity();
2171        // __back_capacity >= 1
2172        size_type __de = __base::size() - __pos;
2173        if (__de == 0)
2174        {
2175            __alloc_traits::construct(__a, _VSTD::addressof(*__base::end()), __v);
2176            ++__base::size();
2177        }
2178        else
2179        {
2180            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
2181            iterator __e = __base::end();
2182            iterator __em1 = _VSTD::prev(__e);
2183            if (__vt == pointer_traits<const_pointer>::pointer_to(*__em1))
2184                __vt = pointer_traits<const_pointer>::pointer_to(*__e);
2185            __alloc_traits::construct(__a, _VSTD::addressof(*__e), _VSTD::move(*__em1));
2186            ++__base::size();
2187            if (__de > 1)
2188                __e = __move_backward_and_check(__e - __de, __em1, __e, __vt);
2189            *--__e = *__vt;
2190        }
2191    }
2192    return __base::begin() + __pos;
2193}
2194
2195template <class _Tp, class _Allocator>
2196typename deque<_Tp, _Allocator>::iterator
2197deque<_Tp, _Allocator>::insert(const_iterator __p, size_type __n, const value_type& __v)
2198{
2199    size_type __pos = __p - __base::begin();
2200    size_type __to_end = __base::size() - __pos;
2201    allocator_type& __a = __base::__alloc();
2202    if (__pos < __to_end)
2203    {   // insert by shifting things backward
2204        if (__n > __front_spare())
2205            __add_front_capacity(__n - __front_spare());
2206        // __n <= __front_spare()
2207        iterator __old_begin = __base::begin();
2208        iterator __i = __old_begin;
2209        if (__n > __pos)
2210        {
2211            for (size_type __m = __n - __pos; __m; --__m, --__base::__start_, ++__base::size())
2212                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), __v);
2213            __n = __pos;
2214        }
2215        if (__n > 0)
2216        {
2217            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
2218            iterator __obn = __old_begin + __n;
2219            __move_construct_backward_and_check(__old_begin, __obn, __i, __vt);
2220            if (__n < __pos)
2221                __old_begin = __move_and_check(__obn, __old_begin + __pos, __old_begin, __vt);
2222            _VSTD::fill_n(__old_begin, __n, *__vt);
2223        }
2224    }
2225    else
2226    {   // insert by shifting things forward
2227        size_type __back_capacity = __back_spare();
2228        if (__n > __back_capacity)
2229            __add_back_capacity(__n - __back_capacity);
2230        // __n <= __back_capacity
2231        iterator __old_end = __base::end();
2232        iterator __i = __old_end;
2233        size_type __de = __base::size() - __pos;
2234        if (__n > __de)
2235        {
2236            for (size_type __m = __n - __de; __m; --__m, ++__i, ++__base::size())
2237                __alloc_traits::construct(__a, _VSTD::addressof(*__i), __v);
2238            __n = __de;
2239        }
2240        if (__n > 0)
2241        {
2242            const_pointer __vt = pointer_traits<const_pointer>::pointer_to(__v);
2243            iterator __oen = __old_end - __n;
2244            __move_construct_and_check(__oen, __old_end, __i, __vt);
2245            if (__n < __de)
2246                __old_end = __move_backward_and_check(__old_end - __de, __oen, __old_end, __vt);
2247            _VSTD::fill_n(__old_end - __n, __n, *__vt);
2248        }
2249    }
2250    return __base::begin() + __pos;
2251}
2252
2253template <class _Tp, class _Allocator>
2254template <class _InputIter>
2255typename deque<_Tp, _Allocator>::iterator
2256deque<_Tp, _Allocator>::insert(const_iterator __p, _InputIter __f, _InputIter __l,
2257                               typename enable_if<__is_cpp17_input_iterator<_InputIter>::value
2258                                               &&!__is_cpp17_forward_iterator<_InputIter>::value>::type*)
2259{
2260    __split_buffer<value_type, allocator_type&> __buf(__base::__alloc());
2261    __buf.__construct_at_end(__f, __l);
2262    typedef typename __split_buffer<value_type, allocator_type&>::iterator __bi;
2263    return insert(__p, move_iterator<__bi>(__buf.begin()), move_iterator<__bi>(__buf.end()));
2264}
2265
2266template <class _Tp, class _Allocator>
2267template <class _ForwardIterator>
2268typename deque<_Tp, _Allocator>::iterator
2269deque<_Tp, _Allocator>::insert(const_iterator __p, _ForwardIterator __f, _ForwardIterator __l,
2270                               typename enable_if<__is_cpp17_forward_iterator<_ForwardIterator>::value
2271                                               &&!__is_cpp17_bidirectional_iterator<_ForwardIterator>::value>::type*)
2272{
2273    size_type __n = _VSTD::distance(__f, __l);
2274    __split_buffer<value_type, allocator_type&> __buf(__n, 0, __base::__alloc());
2275    __buf.__construct_at_end(__f, __l);
2276    typedef typename __split_buffer<value_type, allocator_type&>::iterator __fwd;
2277    return insert(__p, move_iterator<__fwd>(__buf.begin()), move_iterator<__fwd>(__buf.end()));
2278}
2279
2280template <class _Tp, class _Allocator>
2281template <class _BiIter>
2282typename deque<_Tp, _Allocator>::iterator
2283deque<_Tp, _Allocator>::insert(const_iterator __p, _BiIter __f, _BiIter __l,
2284                               typename enable_if<__is_cpp17_bidirectional_iterator<_BiIter>::value>::type*)
2285{
2286    size_type __n = _VSTD::distance(__f, __l);
2287    size_type __pos = __p - __base::begin();
2288    size_type __to_end = __base::size() - __pos;
2289    allocator_type& __a = __base::__alloc();
2290    if (__pos < __to_end)
2291    {   // insert by shifting things backward
2292        if (__n > __front_spare())
2293            __add_front_capacity(__n - __front_spare());
2294        // __n <= __front_spare()
2295        iterator __old_begin = __base::begin();
2296        iterator __i = __old_begin;
2297        _BiIter __m = __f;
2298        if (__n > __pos)
2299        {
2300            __m = __pos < __n / 2 ? _VSTD::prev(__l, __pos) : _VSTD::next(__f, __n - __pos);
2301            for (_BiIter __j = __m; __j != __f; --__base::__start_, ++__base::size())
2302                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), *--__j);
2303            __n = __pos;
2304        }
2305        if (__n > 0)
2306        {
2307            iterator __obn = __old_begin + __n;
2308            for (iterator __j = __obn; __j != __old_begin;)
2309            {
2310                __alloc_traits::construct(__a, _VSTD::addressof(*--__i), _VSTD::move(*--__j));
2311                --__base::__start_;
2312                ++__base::size();
2313            }
2314            if (__n < __pos)
2315                __old_begin = _VSTD::move(__obn, __old_begin + __pos, __old_begin);
2316            _VSTD::copy(__m, __l, __old_begin);
2317        }
2318    }
2319    else
2320    {   // insert by shifting things forward
2321        size_type __back_capacity = __back_spare();
2322        if (__n > __back_capacity)
2323            __add_back_capacity(__n - __back_capacity);
2324        // __n <= __back_capacity
2325        iterator __old_end = __base::end();
2326        iterator __i = __old_end;
2327        _BiIter __m = __l;
2328        size_type __de = __base::size() - __pos;
2329        if (__n > __de)
2330        {
2331            __m = __de < __n / 2 ? _VSTD::next(__f, __de) : _VSTD::prev(__l, __n - __de);
2332            for (_BiIter __j = __m; __j != __l; ++__i, (void) ++__j, ++__base::size())
2333                __alloc_traits::construct(__a, _VSTD::addressof(*__i), *__j);
2334            __n = __de;
2335        }
2336        if (__n > 0)
2337        {
2338            iterator __oen = __old_end - __n;
2339            for (iterator __j = __oen; __j != __old_end; ++__i, ++__j, ++__base::size())
2340                __alloc_traits::construct(__a, _VSTD::addressof(*__i), _VSTD::move(*__j));
2341            if (__n < __de)
2342                __old_end = _VSTD::move_backward(__old_end - __de, __oen, __old_end);
2343            _VSTD::copy_backward(__f, __m, __old_end);
2344        }
2345    }
2346    return __base::begin() + __pos;
2347}
2348
2349template <class _Tp, class _Allocator>
2350template <class _InpIter>
2351void
2352deque<_Tp, _Allocator>::__append(_InpIter __f, _InpIter __l,
2353                                 typename enable_if<__is_cpp17_input_iterator<_InpIter>::value &&
2354                                                   !__is_cpp17_forward_iterator<_InpIter>::value>::type*)
2355{
2356    for (; __f != __l; ++__f)
2357#ifdef _LIBCPP_CXX03_LANG
2358        push_back(*__f);
2359#else
2360        emplace_back(*__f);
2361#endif
2362}
2363
2364template <class _Tp, class _Allocator>
2365template <class _ForIter>
2366void
2367deque<_Tp, _Allocator>::__append(_ForIter __f, _ForIter __l,
2368                                 typename enable_if<__is_cpp17_forward_iterator<_ForIter>::value>::type*)
2369{
2370    size_type __n = _VSTD::distance(__f, __l);
2371    allocator_type& __a = __base::__alloc();
2372    size_type __back_capacity = __back_spare();
2373    if (__n > __back_capacity)
2374        __add_back_capacity(__n - __back_capacity);
2375    // __n <= __back_capacity
2376    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
2377      _ConstructTransaction __tx(this, __br);
2378      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_, (void)++__f) {
2379        __alloc_traits::construct(__a, std::__to_address(__tx.__pos_), *__f);
2380      }
2381    }
2382}
2383
2384template <class _Tp, class _Allocator>
2385void
2386deque<_Tp, _Allocator>::__append(size_type __n)
2387{
2388    allocator_type& __a = __base::__alloc();
2389    size_type __back_capacity = __back_spare();
2390    if (__n > __back_capacity)
2391        __add_back_capacity(__n - __back_capacity);
2392    // __n <= __back_capacity
2393    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
2394      _ConstructTransaction __tx(this, __br);
2395      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
2396        __alloc_traits::construct(__a, std::__to_address(__tx.__pos_));
2397      }
2398    }
2399}
2400
2401template <class _Tp, class _Allocator>
2402void
2403deque<_Tp, _Allocator>::__append(size_type __n, const value_type& __v)
2404{
2405    allocator_type& __a = __base::__alloc();
2406    size_type __back_capacity = __back_spare();
2407    if (__n > __back_capacity)
2408        __add_back_capacity(__n - __back_capacity);
2409    // __n <= __back_capacity
2410    for (__deque_block_range __br : __deque_range(__base::end(), __base::end() + __n)) {
2411      _ConstructTransaction __tx(this, __br);
2412      for (; __tx.__pos_ != __tx.__end_; ++__tx.__pos_) {
2413        __alloc_traits::construct(__a, std::__to_address(__tx.__pos_), __v);
2414      }
2415    }
2416
2417}
2418
2419// Create front capacity for one block of elements.
2420// Strong guarantee.  Either do it or don't touch anything.
2421template <class _Tp, class _Allocator>
2422void
2423deque<_Tp, _Allocator>::__add_front_capacity()
2424{
2425    allocator_type& __a = __base::__alloc();
2426    if (__back_spare() >= __base::__block_size)
2427    {
2428        __base::__start_ += __base::__block_size;
2429        pointer __pt = __base::__map_.back();
2430        __base::__map_.pop_back();
2431        __base::__map_.push_front(__pt);
2432    }
2433    // Else if __base::__map_.size() < __base::__map_.capacity() then we need to allocate 1 buffer
2434    else if (__base::__map_.size() < __base::__map_.capacity())
2435    {   // we can put the new buffer into the map, but don't shift things around
2436        // until all buffers are allocated.  If we throw, we don't need to fix
2437        // anything up (any added buffers are undetectible)
2438        if (__base::__map_.__front_spare() > 0)
2439            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
2440        else
2441        {
2442            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2443            // Done allocating, reorder capacity
2444            pointer __pt = __base::__map_.back();
2445            __base::__map_.pop_back();
2446            __base::__map_.push_front(__pt);
2447        }
2448        __base::__start_ = __base::__map_.size() == 1 ?
2449                               __base::__block_size / 2 :
2450                               __base::__start_ + __base::__block_size;
2451    }
2452    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
2453    else
2454    {
2455        __split_buffer<pointer, typename __base::__pointer_allocator&>
2456            __buf(max<size_type>(2 * __base::__map_.capacity(), 1),
2457                  0, __base::__map_.__alloc());
2458
2459        typedef __allocator_destructor<_Allocator> _Dp;
2460        unique_ptr<pointer, _Dp> __hold(
2461            __alloc_traits::allocate(__a, __base::__block_size),
2462                _Dp(__a, __base::__block_size));
2463        __buf.push_back(__hold.get());
2464        __hold.release();
2465
2466        for (typename __base::__map_pointer __i = __base::__map_.begin();
2467                __i != __base::__map_.end(); ++__i)
2468            __buf.push_back(*__i);
2469        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
2470        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
2471        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
2472        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
2473        __base::__start_ = __base::__map_.size() == 1 ?
2474                               __base::__block_size / 2 :
2475                               __base::__start_ + __base::__block_size;
2476    }
2477}
2478
2479// Create front capacity for __n elements.
2480// Strong guarantee.  Either do it or don't touch anything.
2481template <class _Tp, class _Allocator>
2482void
2483deque<_Tp, _Allocator>::__add_front_capacity(size_type __n)
2484{
2485    allocator_type& __a = __base::__alloc();
2486    size_type __nb = __recommend_blocks(__n + __base::__map_.empty());
2487    // Number of unused blocks at back:
2488    size_type __back_capacity = __back_spare() / __base::__block_size;
2489    __back_capacity = _VSTD::min(__back_capacity, __nb);  // don't take more than you need
2490    __nb -= __back_capacity;  // number of blocks need to allocate
2491    // If __nb == 0, then we have sufficient capacity.
2492    if (__nb == 0)
2493    {
2494        __base::__start_ += __base::__block_size * __back_capacity;
2495        for (; __back_capacity > 0; --__back_capacity)
2496        {
2497            pointer __pt = __base::__map_.back();
2498            __base::__map_.pop_back();
2499            __base::__map_.push_front(__pt);
2500        }
2501    }
2502    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
2503    else if (__nb <= __base::__map_.capacity() - __base::__map_.size())
2504    {   // we can put the new buffers into the map, but don't shift things around
2505        // until all buffers are allocated.  If we throw, we don't need to fix
2506        // anything up (any added buffers are undetectible)
2507        for (; __nb > 0; --__nb, __base::__start_ += __base::__block_size - (__base::__map_.size() == 1))
2508        {
2509            if (__base::__map_.__front_spare() == 0)
2510                break;
2511            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
2512        }
2513        for (; __nb > 0; --__nb, ++__back_capacity)
2514            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2515        // Done allocating, reorder capacity
2516        __base::__start_ += __back_capacity * __base::__block_size;
2517        for (; __back_capacity > 0; --__back_capacity)
2518        {
2519            pointer __pt = __base::__map_.back();
2520            __base::__map_.pop_back();
2521            __base::__map_.push_front(__pt);
2522        }
2523    }
2524    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
2525    else
2526    {
2527        size_type __ds = (__nb + __back_capacity) * __base::__block_size - __base::__map_.empty();
2528        __split_buffer<pointer, typename __base::__pointer_allocator&>
2529            __buf(max<size_type>(2* __base::__map_.capacity(),
2530                                 __nb + __base::__map_.size()),
2531                  0, __base::__map_.__alloc());
2532#ifndef _LIBCPP_NO_EXCEPTIONS
2533        try
2534        {
2535#endif  // _LIBCPP_NO_EXCEPTIONS
2536            for (; __nb > 0; --__nb)
2537                __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2538#ifndef _LIBCPP_NO_EXCEPTIONS
2539        }
2540        catch (...)
2541        {
2542            for (typename __base::__map_pointer __i = __buf.begin();
2543                    __i != __buf.end(); ++__i)
2544                __alloc_traits::deallocate(__a, *__i, __base::__block_size);
2545            throw;
2546        }
2547#endif  // _LIBCPP_NO_EXCEPTIONS
2548        for (; __back_capacity > 0; --__back_capacity)
2549        {
2550            __buf.push_back(__base::__map_.back());
2551            __base::__map_.pop_back();
2552        }
2553        for (typename __base::__map_pointer __i = __base::__map_.begin();
2554                __i != __base::__map_.end(); ++__i)
2555            __buf.push_back(*__i);
2556        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
2557        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
2558        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
2559        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
2560        __base::__start_ += __ds;
2561    }
2562}
2563
2564// Create back capacity for one block of elements.
2565// Strong guarantee.  Either do it or don't touch anything.
2566template <class _Tp, class _Allocator>
2567void
2568deque<_Tp, _Allocator>::__add_back_capacity()
2569{
2570    allocator_type& __a = __base::__alloc();
2571    if (__front_spare() >= __base::__block_size)
2572    {
2573        __base::__start_ -= __base::__block_size;
2574        pointer __pt = __base::__map_.front();
2575        __base::__map_.pop_front();
2576        __base::__map_.push_back(__pt);
2577    }
2578    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
2579    else if (__base::__map_.size() < __base::__map_.capacity())
2580    {   // we can put the new buffer into the map, but don't shift things around
2581        // until it is allocated.  If we throw, we don't need to fix
2582        // anything up (any added buffers are undetectible)
2583        if (__base::__map_.__back_spare() != 0)
2584            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2585        else
2586        {
2587            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
2588            // Done allocating, reorder capacity
2589            pointer __pt = __base::__map_.front();
2590            __base::__map_.pop_front();
2591            __base::__map_.push_back(__pt);
2592        }
2593    }
2594    // Else need to allocate 1 buffer, *and* we need to reallocate __map_.
2595    else
2596    {
2597        __split_buffer<pointer, typename __base::__pointer_allocator&>
2598            __buf(max<size_type>(2* __base::__map_.capacity(), 1),
2599                  __base::__map_.size(),
2600                  __base::__map_.__alloc());
2601
2602        typedef __allocator_destructor<_Allocator> _Dp;
2603        unique_ptr<pointer, _Dp> __hold(
2604            __alloc_traits::allocate(__a, __base::__block_size),
2605                _Dp(__a, __base::__block_size));
2606        __buf.push_back(__hold.get());
2607        __hold.release();
2608
2609        for (typename __base::__map_pointer __i = __base::__map_.end();
2610                __i != __base::__map_.begin();)
2611            __buf.push_front(*--__i);
2612        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
2613        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
2614        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
2615        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
2616    }
2617}
2618
2619// Create back capacity for __n elements.
2620// Strong guarantee.  Either do it or don't touch anything.
2621template <class _Tp, class _Allocator>
2622void
2623deque<_Tp, _Allocator>::__add_back_capacity(size_type __n)
2624{
2625    allocator_type& __a = __base::__alloc();
2626    size_type __nb = __recommend_blocks(__n + __base::__map_.empty());
2627    // Number of unused blocks at front:
2628    size_type __front_capacity = __front_spare() / __base::__block_size;
2629    __front_capacity = _VSTD::min(__front_capacity, __nb);  // don't take more than you need
2630    __nb -= __front_capacity;  // number of blocks need to allocate
2631    // If __nb == 0, then we have sufficient capacity.
2632    if (__nb == 0)
2633    {
2634        __base::__start_ -= __base::__block_size * __front_capacity;
2635        for (; __front_capacity > 0; --__front_capacity)
2636        {
2637            pointer __pt = __base::__map_.front();
2638            __base::__map_.pop_front();
2639            __base::__map_.push_back(__pt);
2640        }
2641    }
2642    // Else if __nb <= __map_.capacity() - __map_.size() then we need to allocate __nb buffers
2643    else if (__nb <= __base::__map_.capacity() - __base::__map_.size())
2644    {   // we can put the new buffers into the map, but don't shift things around
2645        // until all buffers are allocated.  If we throw, we don't need to fix
2646        // anything up (any added buffers are undetectible)
2647        for (; __nb > 0; --__nb)
2648        {
2649            if (__base::__map_.__back_spare() == 0)
2650                break;
2651            __base::__map_.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2652        }
2653        for (; __nb > 0; --__nb, ++__front_capacity, __base::__start_ +=
2654                                 __base::__block_size - (__base::__map_.size() == 1))
2655            __base::__map_.push_front(__alloc_traits::allocate(__a, __base::__block_size));
2656        // Done allocating, reorder capacity
2657        __base::__start_ -= __base::__block_size * __front_capacity;
2658        for (; __front_capacity > 0; --__front_capacity)
2659        {
2660            pointer __pt = __base::__map_.front();
2661            __base::__map_.pop_front();
2662            __base::__map_.push_back(__pt);
2663        }
2664    }
2665    // Else need to allocate __nb buffers, *and* we need to reallocate __map_.
2666    else
2667    {
2668        size_type __ds = __front_capacity * __base::__block_size;
2669        __split_buffer<pointer, typename __base::__pointer_allocator&>
2670            __buf(max<size_type>(2* __base::__map_.capacity(),
2671                                 __nb + __base::__map_.size()),
2672                  __base::__map_.size() - __front_capacity,
2673                  __base::__map_.__alloc());
2674#ifndef _LIBCPP_NO_EXCEPTIONS
2675        try
2676        {
2677#endif  // _LIBCPP_NO_EXCEPTIONS
2678            for (; __nb > 0; --__nb)
2679                __buf.push_back(__alloc_traits::allocate(__a, __base::__block_size));
2680#ifndef _LIBCPP_NO_EXCEPTIONS
2681        }
2682        catch (...)
2683        {
2684            for (typename __base::__map_pointer __i = __buf.begin();
2685                    __i != __buf.end(); ++__i)
2686                __alloc_traits::deallocate(__a, *__i, __base::__block_size);
2687            throw;
2688        }
2689#endif  // _LIBCPP_NO_EXCEPTIONS
2690        for (; __front_capacity > 0; --__front_capacity)
2691        {
2692            __buf.push_back(__base::__map_.front());
2693            __base::__map_.pop_front();
2694        }
2695        for (typename __base::__map_pointer __i = __base::__map_.end();
2696                __i != __base::__map_.begin();)
2697            __buf.push_front(*--__i);
2698        _VSTD::swap(__base::__map_.__first_, __buf.__first_);
2699        _VSTD::swap(__base::__map_.__begin_, __buf.__begin_);
2700        _VSTD::swap(__base::__map_.__end_, __buf.__end_);
2701        _VSTD::swap(__base::__map_.__end_cap(), __buf.__end_cap());
2702        __base::__start_ -= __ds;
2703    }
2704}
2705
2706template <class _Tp, class _Allocator>
2707void
2708deque<_Tp, _Allocator>::pop_front()
2709{
2710    allocator_type& __a = __base::__alloc();
2711    __alloc_traits::destroy(__a, __to_address(*(__base::__map_.begin() +
2712                                                    __base::__start_ / __base::__block_size) +
2713                                                    __base::__start_ % __base::__block_size));
2714    --__base::size();
2715    ++__base::__start_;
2716    __maybe_remove_front_spare();
2717}
2718
2719template <class _Tp, class _Allocator>
2720void
2721deque<_Tp, _Allocator>::pop_back()
2722{
2723    _LIBCPP_ASSERT(!empty(), "deque::pop_back called for empty deque");
2724    allocator_type& __a = __base::__alloc();
2725    size_type __p = __base::size() + __base::__start_ - 1;
2726    __alloc_traits::destroy(__a, __to_address(*(__base::__map_.begin() +
2727                                                    __p / __base::__block_size) +
2728                                                    __p % __base::__block_size));
2729    --__base::size();
2730    __maybe_remove_back_spare();
2731}
2732
2733// move assign [__f, __l) to [__r, __r + (__l-__f)).
2734// If __vt points into [__f, __l), then subtract (__f - __r) from __vt.
2735template <class _Tp, class _Allocator>
2736typename deque<_Tp, _Allocator>::iterator
2737deque<_Tp, _Allocator>::__move_and_check(iterator __f, iterator __l, iterator __r,
2738                                         const_pointer& __vt)
2739{
2740    // as if
2741    //   for (; __f != __l; ++__f, ++__r)
2742    //       *__r = _VSTD::move(*__f);
2743    difference_type __n = __l - __f;
2744    while (__n > 0)
2745    {
2746        pointer __fb = __f.__ptr_;
2747        pointer __fe = *__f.__m_iter_ + __base::__block_size;
2748        difference_type __bs = __fe - __fb;
2749        if (__bs > __n)
2750        {
2751            __bs = __n;
2752            __fe = __fb + __bs;
2753        }
2754        if (__fb <= __vt && __vt < __fe)
2755            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) -= __f - __r).__ptr_;
2756        __r = _VSTD::move(__fb, __fe, __r);
2757        __n -= __bs;
2758        __f += __bs;
2759    }
2760    return __r;
2761}
2762
2763// move assign [__f, __l) to [__r - (__l-__f), __r) backwards.
2764// If __vt points into [__f, __l), then add (__r - __l) to __vt.
2765template <class _Tp, class _Allocator>
2766typename deque<_Tp, _Allocator>::iterator
2767deque<_Tp, _Allocator>::__move_backward_and_check(iterator __f, iterator __l, iterator __r,
2768                                                  const_pointer& __vt)
2769{
2770    // as if
2771    //   while (__f != __l)
2772    //       *--__r = _VSTD::move(*--__l);
2773    difference_type __n = __l - __f;
2774    while (__n > 0)
2775    {
2776        --__l;
2777        pointer __lb = *__l.__m_iter_;
2778        pointer __le = __l.__ptr_ + 1;
2779        difference_type __bs = __le - __lb;
2780        if (__bs > __n)
2781        {
2782            __bs = __n;
2783            __lb = __le - __bs;
2784        }
2785        if (__lb <= __vt && __vt < __le)
2786            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) += __r - __l - 1).__ptr_;
2787        __r = _VSTD::move_backward(__lb, __le, __r);
2788        __n -= __bs;
2789        __l -= __bs - 1;
2790    }
2791    return __r;
2792}
2793
2794// move construct [__f, __l) to [__r, __r + (__l-__f)).
2795// If __vt points into [__f, __l), then add (__r - __f) to __vt.
2796template <class _Tp, class _Allocator>
2797void
2798deque<_Tp, _Allocator>::__move_construct_and_check(iterator __f, iterator __l,
2799                                                   iterator __r, const_pointer& __vt)
2800{
2801    allocator_type& __a = __base::__alloc();
2802    // as if
2803    //   for (; __f != __l; ++__r, ++__f, ++__base::size())
2804    //       __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__f));
2805    difference_type __n = __l - __f;
2806    while (__n > 0)
2807    {
2808        pointer __fb = __f.__ptr_;
2809        pointer __fe = *__f.__m_iter_ + __base::__block_size;
2810        difference_type __bs = __fe - __fb;
2811        if (__bs > __n)
2812        {
2813            __bs = __n;
2814            __fe = __fb + __bs;
2815        }
2816        if (__fb <= __vt && __vt < __fe)
2817            __vt = (const_iterator(static_cast<__map_const_pointer>(__f.__m_iter_), __vt) += __r - __f).__ptr_;
2818        for (; __fb != __fe; ++__fb, ++__r, ++__base::size())
2819            __alloc_traits::construct(__a, _VSTD::addressof(*__r), _VSTD::move(*__fb));
2820        __n -= __bs;
2821        __f += __bs;
2822    }
2823}
2824
2825// move construct [__f, __l) to [__r - (__l-__f), __r) backwards.
2826// If __vt points into [__f, __l), then subtract (__l - __r) from __vt.
2827template <class _Tp, class _Allocator>
2828void
2829deque<_Tp, _Allocator>::__move_construct_backward_and_check(iterator __f, iterator __l,
2830                                                            iterator __r, const_pointer& __vt)
2831{
2832    allocator_type& __a = __base::__alloc();
2833    // as if
2834    //   for (iterator __j = __l; __j != __f;)
2835    //   {
2836    //       __alloc_traitsconstruct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__j));
2837    //       --__base::__start_;
2838    //       ++__base::size();
2839    //   }
2840    difference_type __n = __l - __f;
2841    while (__n > 0)
2842    {
2843        --__l;
2844        pointer __lb = *__l.__m_iter_;
2845        pointer __le = __l.__ptr_ + 1;
2846        difference_type __bs = __le - __lb;
2847        if (__bs > __n)
2848        {
2849            __bs = __n;
2850            __lb = __le - __bs;
2851        }
2852        if (__lb <= __vt && __vt < __le)
2853            __vt = (const_iterator(static_cast<__map_const_pointer>(__l.__m_iter_), __vt) -= __l - __r + 1).__ptr_;
2854        while (__le != __lb)
2855        {
2856            __alloc_traits::construct(__a, _VSTD::addressof(*--__r), _VSTD::move(*--__le));
2857            --__base::__start_;
2858            ++__base::size();
2859        }
2860        __n -= __bs;
2861        __l -= __bs - 1;
2862    }
2863}
2864
2865template <class _Tp, class _Allocator>
2866typename deque<_Tp, _Allocator>::iterator
2867deque<_Tp, _Allocator>::erase(const_iterator __f)
2868{
2869    iterator __b = __base::begin();
2870    difference_type __pos = __f - __b;
2871    iterator __p = __b + __pos;
2872    allocator_type& __a = __base::__alloc();
2873    if (static_cast<size_t>(__pos) <= (__base::size() - 1) / 2)
2874    {   // erase from front
2875        _VSTD::move_backward(__b, __p, _VSTD::next(__p));
2876        __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
2877        --__base::size();
2878        ++__base::__start_;
2879        __maybe_remove_front_spare();
2880    }
2881    else
2882    {   // erase from back
2883        iterator __i = _VSTD::move(_VSTD::next(__p), __base::end(), __p);
2884        __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
2885        --__base::size();
2886        __maybe_remove_back_spare();
2887    }
2888    return __base::begin() + __pos;
2889}
2890
2891template <class _Tp, class _Allocator>
2892typename deque<_Tp, _Allocator>::iterator
2893deque<_Tp, _Allocator>::erase(const_iterator __f, const_iterator __l)
2894{
2895    difference_type __n = __l - __f;
2896    iterator __b = __base::begin();
2897    difference_type __pos = __f - __b;
2898    iterator __p = __b + __pos;
2899    if (__n > 0)
2900    {
2901        allocator_type& __a = __base::__alloc();
2902        if (static_cast<size_t>(__pos) <= (__base::size() - __n) / 2)
2903        {   // erase from front
2904            iterator __i = _VSTD::move_backward(__b, __p, __p + __n);
2905            for (; __b != __i; ++__b)
2906                __alloc_traits::destroy(__a, _VSTD::addressof(*__b));
2907            __base::size() -= __n;
2908            __base::__start_ += __n;
2909            while (__maybe_remove_front_spare()) {
2910            }
2911        }
2912        else
2913        {   // erase from back
2914            iterator __i = _VSTD::move(__p + __n, __base::end(), __p);
2915            for (iterator __e = __base::end(); __i != __e; ++__i)
2916                __alloc_traits::destroy(__a, _VSTD::addressof(*__i));
2917            __base::size() -= __n;
2918            while (__maybe_remove_back_spare()) {
2919            }
2920        }
2921    }
2922    return __base::begin() + __pos;
2923}
2924
2925template <class _Tp, class _Allocator>
2926void
2927deque<_Tp, _Allocator>::__erase_to_end(const_iterator __f)
2928{
2929    iterator __e = __base::end();
2930    difference_type __n = __e - __f;
2931    if (__n > 0)
2932    {
2933        allocator_type& __a = __base::__alloc();
2934        iterator __b = __base::begin();
2935        difference_type __pos = __f - __b;
2936        for (iterator __p = __b + __pos; __p != __e; ++__p)
2937            __alloc_traits::destroy(__a, _VSTD::addressof(*__p));
2938        __base::size() -= __n;
2939        while (__maybe_remove_back_spare()) {
2940        }
2941    }
2942}
2943
2944template <class _Tp, class _Allocator>
2945inline
2946void
2947deque<_Tp, _Allocator>::swap(deque& __c)
2948#if _LIBCPP_STD_VER >= 14
2949        _NOEXCEPT
2950#else
2951        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
2952                    __is_nothrow_swappable<allocator_type>::value)
2953#endif
2954{
2955    __base::swap(__c);
2956}
2957
2958template <class _Tp, class _Allocator>
2959inline
2960void
2961deque<_Tp, _Allocator>::clear() _NOEXCEPT
2962{
2963    __base::clear();
2964}
2965
2966template <class _Tp, class _Allocator>
2967inline _LIBCPP_INLINE_VISIBILITY
2968bool
2969operator==(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2970{
2971    const typename deque<_Tp, _Allocator>::size_type __sz = __x.size();
2972    return __sz == __y.size() && _VSTD::equal(__x.begin(), __x.end(), __y.begin());
2973}
2974
2975template <class _Tp, class _Allocator>
2976inline _LIBCPP_INLINE_VISIBILITY
2977bool
2978operator!=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2979{
2980    return !(__x == __y);
2981}
2982
2983template <class _Tp, class _Allocator>
2984inline _LIBCPP_INLINE_VISIBILITY
2985bool
2986operator< (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2987{
2988    return _VSTD::lexicographical_compare(__x.begin(), __x.end(), __y.begin(), __y.end());
2989}
2990
2991template <class _Tp, class _Allocator>
2992inline _LIBCPP_INLINE_VISIBILITY
2993bool
2994operator> (const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
2995{
2996    return __y < __x;
2997}
2998
2999template <class _Tp, class _Allocator>
3000inline _LIBCPP_INLINE_VISIBILITY
3001bool
3002operator>=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
3003{
3004    return !(__x < __y);
3005}
3006
3007template <class _Tp, class _Allocator>
3008inline _LIBCPP_INLINE_VISIBILITY
3009bool
3010operator<=(const deque<_Tp, _Allocator>& __x, const deque<_Tp, _Allocator>& __y)
3011{
3012    return !(__y < __x);
3013}
3014
3015template <class _Tp, class _Allocator>
3016inline _LIBCPP_INLINE_VISIBILITY
3017void
3018swap(deque<_Tp, _Allocator>& __x, deque<_Tp, _Allocator>& __y)
3019    _NOEXCEPT_(_NOEXCEPT_(__x.swap(__y)))
3020{
3021    __x.swap(__y);
3022}
3023
3024#if _LIBCPP_STD_VER > 17
3025template <class _Tp, class _Allocator, class _Up>
3026inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type
3027erase(deque<_Tp, _Allocator>& __c, const _Up& __v) {
3028  auto __old_size = __c.size();
3029  __c.erase(_VSTD::remove(__c.begin(), __c.end(), __v), __c.end());
3030  return __old_size - __c.size();
3031}
3032
3033template <class _Tp, class _Allocator, class _Predicate>
3034inline _LIBCPP_INLINE_VISIBILITY typename deque<_Tp, _Allocator>::size_type
3035erase_if(deque<_Tp, _Allocator>& __c, _Predicate __pred) {
3036  auto __old_size = __c.size();
3037  __c.erase(_VSTD::remove_if(__c.begin(), __c.end(), __pred), __c.end());
3038  return __old_size - __c.size();
3039}
3040#endif
3041
3042
3043_LIBCPP_END_NAMESPACE_STD
3044
3045_LIBCPP_POP_MACROS
3046
3047#endif  // _LIBCPP_DEQUE
3048