1// -*- C++ -*-
2//===-------------------------- iterator ----------------------------------===//
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_ITERATOR
11#define _LIBCPP_ITERATOR
12
13/*
14    iterator synopsis
15
16namespace std
17{
18
19template<class Iterator>
20struct iterator_traits
21{
22    typedef typename Iterator::difference_type difference_type;
23    typedef typename Iterator::value_type value_type;
24    typedef typename Iterator::pointer pointer;
25    typedef typename Iterator::reference reference;
26    typedef typename Iterator::iterator_category iterator_category;
27};
28
29template<class T>
30struct iterator_traits<T*>
31{
32    typedef ptrdiff_t difference_type;
33    typedef T value_type;
34    typedef T* pointer;
35    typedef T& reference;
36    typedef random_access_iterator_tag iterator_category;
37};
38
39template<class Category, class T, class Distance = ptrdiff_t,
40         class Pointer = T*, class Reference = T&>
41struct iterator
42{
43    typedef T         value_type;
44    typedef Distance  difference_type;
45    typedef Pointer   pointer;
46    typedef Reference reference;
47    typedef Category  iterator_category;
48};
49
50struct input_iterator_tag  {};
51struct output_iterator_tag {};
52struct forward_iterator_tag       : public input_iterator_tag         {};
53struct bidirectional_iterator_tag : public forward_iterator_tag       {};
54struct random_access_iterator_tag : public bidirectional_iterator_tag {};
55
56// 27.4.3, iterator operations
57// extension: second argument not conforming to C++03
58template <class InputIterator>  // constexpr in C++17
59  constexpr void advance(InputIterator& i,
60             typename iterator_traits<InputIterator>::difference_type n);
61
62template <class InputIterator>  // constexpr in C++17
63  constexpr typename iterator_traits<InputIterator>::difference_type
64    distance(InputIterator first, InputIterator last);
65
66template <class InputIterator>  // constexpr in C++17
67  constexpr InputIterator next(InputIterator x,
68typename iterator_traits<InputIterator>::difference_type n = 1);
69
70template <class BidirectionalIterator>  // constexpr in C++17
71  constexpr BidirectionalIterator prev(BidirectionalIterator x,
72    typename iterator_traits<BidirectionalIterator>::difference_type n = 1);
73
74template <class Iterator>
75class reverse_iterator
76    : public iterator<typename iterator_traits<Iterator>::iterator_category,
77                      typename iterator_traits<Iterator>::value_type,
78                      typename iterator_traits<Iterator>::difference_type,
79                      typename iterator_traits<Iterator>::pointer,
80                      typename iterator_traits<Iterator>::reference>
81{
82protected:
83    Iterator current;
84public:
85    typedef Iterator                                            iterator_type;
86    typedef typename iterator_traits<Iterator>::difference_type difference_type;
87    typedef typename iterator_traits<Iterator>::reference       reference;
88    typedef typename iterator_traits<Iterator>::pointer         pointer;
89
90    constexpr reverse_iterator();
91    constexpr explicit reverse_iterator(Iterator x);
92    template <class U> constexpr reverse_iterator(const reverse_iterator<U>& u);
93    template <class U> constexpr reverse_iterator& operator=(const reverse_iterator<U>& u);
94    constexpr Iterator base() const;
95    constexpr reference operator*() const;
96    constexpr pointer   operator->() const;
97    constexpr reverse_iterator& operator++();
98    constexpr reverse_iterator  operator++(int);
99    constexpr reverse_iterator& operator--();
100    constexpr reverse_iterator  operator--(int);
101    constexpr reverse_iterator  operator+ (difference_type n) const;
102    constexpr reverse_iterator& operator+=(difference_type n);
103    constexpr reverse_iterator  operator- (difference_type n) const;
104    constexpr reverse_iterator& operator-=(difference_type n);
105    constexpr reference         operator[](difference_type n) const;
106};
107
108template <class Iterator1, class Iterator2>
109constexpr bool                          // constexpr in C++17
110operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
111
112template <class Iterator1, class Iterator2>
113constexpr bool                          // constexpr in C++17
114operator<(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
115
116template <class Iterator1, class Iterator2>
117constexpr bool                          // constexpr in C++17
118operator!=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
119
120template <class Iterator1, class Iterator2>
121constexpr bool                          // constexpr in C++17
122operator>(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
123
124template <class Iterator1, class Iterator2>
125constexpr bool                          // constexpr in C++17
126operator>=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
127
128template <class Iterator1, class Iterator2>
129constexpr bool                          // constexpr in C++17
130operator<=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
131
132template <class Iterator1, class Iterator2>
133constexpr auto
134operator-(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y)
135-> decltype(__y.base() - __x.base());   // constexpr in C++17
136
137template <class Iterator>
138constexpr reverse_iterator<Iterator>
139operator+(typename reverse_iterator<Iterator>::difference_type n,
140          const reverse_iterator<Iterator>& x);   // constexpr in C++17
141
142template <class Iterator>
143constexpr reverse_iterator<Iterator> make_reverse_iterator(Iterator i); // C++14, constexpr in C++17
144
145template <class Container>
146class back_insert_iterator
147{
148protected:
149    Container* container;
150public:
151    typedef Container                   container_type;
152    typedef void                        value_type;
153    typedef void                        difference_type;
154    typedef void                        reference;
155    typedef void                        pointer;
156
157    explicit back_insert_iterator(Container& x);
158    back_insert_iterator& operator=(const typename Container::value_type& value);
159    back_insert_iterator& operator*();
160    back_insert_iterator& operator++();
161    back_insert_iterator  operator++(int);
162};
163
164template <class Container> back_insert_iterator<Container> back_inserter(Container& x);
165
166template <class Container>
167class front_insert_iterator
168{
169protected:
170    Container* container;
171public:
172    typedef Container                    container_type;
173    typedef void                         value_type;
174    typedef void                         difference_type;
175    typedef void                         reference;
176    typedef void                         pointer;
177
178    explicit front_insert_iterator(Container& x);
179    front_insert_iterator& operator=(const typename Container::value_type& value);
180    front_insert_iterator& operator*();
181    front_insert_iterator& operator++();
182    front_insert_iterator  operator++(int);
183};
184
185template <class Container> front_insert_iterator<Container> front_inserter(Container& x);
186
187template <class Container>
188class insert_iterator
189{
190protected:
191    Container* container;
192    typename Container::iterator iter;
193public:
194    typedef Container              container_type;
195    typedef void                   value_type;
196    typedef void                   difference_type;
197    typedef void                   reference;
198    typedef void                   pointer;
199
200    insert_iterator(Container& x, typename Container::iterator i);
201    insert_iterator& operator=(const typename Container::value_type& value);
202    insert_iterator& operator*();
203    insert_iterator& operator++();
204    insert_iterator& operator++(int);
205};
206
207template <class Container, class Iterator>
208insert_iterator<Container> inserter(Container& x, Iterator i);
209
210template <class Iterator>
211class move_iterator {
212public:
213    typedef Iterator                                              iterator_type;
214    typedef typename iterator_traits<Iterator>::difference_type   difference_type;
215    typedef Iterator                                              pointer;
216    typedef typename iterator_traits<Iterator>::value_type        value_type;
217    typedef typename iterator_traits<Iterator>::iterator_category iterator_category;
218    typedef value_type&&                                          reference;
219
220    constexpr move_iterator();  // all the constexprs are in C++17
221    constexpr explicit move_iterator(Iterator i);
222    template <class U>
223      constexpr move_iterator(const move_iterator<U>& u);
224    template <class U>
225      constexpr move_iterator& operator=(const move_iterator<U>& u);
226    constexpr iterator_type base() const;
227    constexpr reference operator*() const;
228    constexpr pointer operator->() const;
229    constexpr move_iterator& operator++();
230    constexpr move_iterator operator++(int);
231    constexpr move_iterator& operator--();
232    constexpr move_iterator operator--(int);
233    constexpr move_iterator operator+(difference_type n) const;
234    constexpr move_iterator& operator+=(difference_type n);
235    constexpr move_iterator operator-(difference_type n) const;
236    constexpr move_iterator& operator-=(difference_type n);
237    constexpr unspecified operator[](difference_type n) const;
238private:
239    Iterator current; // exposition only
240};
241
242template <class Iterator1, class Iterator2>
243constexpr bool   // constexpr in C++17
244operator==(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
245
246template <class Iterator1, class Iterator2>
247constexpr bool   // constexpr in C++17
248operator!=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
249
250template <class Iterator1, class Iterator2>
251constexpr bool   // constexpr in C++17
252operator<(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
253
254template <class Iterator1, class Iterator2>
255constexpr bool   // constexpr in C++17
256operator<=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
257
258template <class Iterator1, class Iterator2>
259constexpr bool   // constexpr in C++17
260operator>(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
261
262template <class Iterator1, class Iterator2>
263constexpr bool   // constexpr in C++17
264operator>=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
265
266template <class Iterator1, class Iterator2>
267constexpr auto   // constexpr in C++17
268operator-(const move_iterator<Iterator1>& x,
269          const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
270
271template <class Iterator>
272constexpr move_iterator<Iterator> operator+(   // constexpr in C++17
273            typename move_iterator<Iterator>::difference_type n,
274            const move_iterator<Iterator>& x);
275
276template <class Iterator>   // constexpr in C++17
277constexpr  move_iterator<Iterator> make_move_iterator(const Iterator& i);
278
279
280template <class T, class charT = char, class traits = char_traits<charT>, class Distance = ptrdiff_t>
281class istream_iterator
282    : public iterator<input_iterator_tag, T, Distance, const T*, const T&>
283{
284public:
285    typedef charT char_type;
286    typedef traits traits_type;
287    typedef basic_istream<charT,traits> istream_type;
288
289    constexpr istream_iterator();
290    istream_iterator(istream_type& s);
291    istream_iterator(const istream_iterator& x);
292    ~istream_iterator();
293
294    const T& operator*() const;
295    const T* operator->() const;
296    istream_iterator& operator++();
297    istream_iterator  operator++(int);
298};
299
300template <class T, class charT, class traits, class Distance>
301bool operator==(const istream_iterator<T,charT,traits,Distance>& x,
302                const istream_iterator<T,charT,traits,Distance>& y);
303template <class T, class charT, class traits, class Distance>
304bool operator!=(const istream_iterator<T,charT,traits,Distance>& x,
305                const istream_iterator<T,charT,traits,Distance>& y);
306
307template <class T, class charT = char, class traits = char_traits<charT> >
308class ostream_iterator
309    : public iterator<output_iterator_tag, void, void, void ,void>
310{
311public:
312    typedef charT char_type;
313    typedef traits traits_type;
314    typedef basic_ostream<charT,traits> ostream_type;
315
316    ostream_iterator(ostream_type& s);
317    ostream_iterator(ostream_type& s, const charT* delimiter);
318    ostream_iterator(const ostream_iterator& x);
319    ~ostream_iterator();
320    ostream_iterator& operator=(const T& value);
321
322    ostream_iterator& operator*();
323    ostream_iterator& operator++();
324    ostream_iterator& operator++(int);
325};
326
327template<class charT, class traits = char_traits<charT> >
328class istreambuf_iterator
329    : public iterator<input_iterator_tag, charT,
330                      typename traits::off_type, unspecified,
331                      charT>
332{
333public:
334    typedef charT                         char_type;
335    typedef traits                        traits_type;
336    typedef typename traits::int_type     int_type;
337    typedef basic_streambuf<charT,traits> streambuf_type;
338    typedef basic_istream<charT,traits>   istream_type;
339
340    istreambuf_iterator() noexcept;
341    istreambuf_iterator(istream_type& s) noexcept;
342    istreambuf_iterator(streambuf_type* s) noexcept;
343    istreambuf_iterator(a-private-type) noexcept;
344
345    charT                operator*() const;
346    pointer operator->() const;
347    istreambuf_iterator& operator++();
348    a-private-type       operator++(int);
349
350    bool equal(const istreambuf_iterator& b) const;
351};
352
353template <class charT, class traits>
354bool operator==(const istreambuf_iterator<charT,traits>& a,
355                const istreambuf_iterator<charT,traits>& b);
356template <class charT, class traits>
357bool operator!=(const istreambuf_iterator<charT,traits>& a,
358                const istreambuf_iterator<charT,traits>& b);
359
360template <class charT, class traits = char_traits<charT> >
361class ostreambuf_iterator
362    : public iterator<output_iterator_tag, void, void, void, void>
363{
364public:
365    typedef charT                         char_type;
366    typedef traits                        traits_type;
367    typedef basic_streambuf<charT,traits> streambuf_type;
368    typedef basic_ostream<charT,traits>   ostream_type;
369
370    ostreambuf_iterator(ostream_type& s) noexcept;
371    ostreambuf_iterator(streambuf_type* s) noexcept;
372    ostreambuf_iterator& operator=(charT c);
373    ostreambuf_iterator& operator*();
374    ostreambuf_iterator& operator++();
375    ostreambuf_iterator& operator++(int);
376    bool failed() const noexcept;
377};
378
379template <class C> constexpr auto begin(C& c) -> decltype(c.begin());
380template <class C> constexpr auto begin(const C& c) -> decltype(c.begin());
381template <class C> constexpr auto end(C& c) -> decltype(c.end());
382template <class C> constexpr auto end(const C& c) -> decltype(c.end());
383template <class T, size_t N> constexpr T* begin(T (&array)[N]);
384template <class T, size_t N> constexpr T* end(T (&array)[N]);
385
386template <class C> auto constexpr cbegin(const C& c) -> decltype(std::begin(c));        // C++14
387template <class C> auto constexpr cend(const C& c) -> decltype(std::end(c));            // C++14
388template <class C> auto constexpr rbegin(C& c) -> decltype(c.rbegin());                 // C++14
389template <class C> auto constexpr rbegin(const C& c) -> decltype(c.rbegin());           // C++14
390template <class C> auto constexpr rend(C& c) -> decltype(c.rend());                     // C++14
391template <class C> constexpr auto rend(const C& c) -> decltype(c.rend());               // C++14
392template <class E> reverse_iterator<const E*> constexpr rbegin(initializer_list<E> il); // C++14
393template <class E> reverse_iterator<const E*> constexpr rend(initializer_list<E> il);   // C++14
394template <class T, size_t N> reverse_iterator<T*> constexpr rbegin(T (&array)[N]);      // C++14
395template <class T, size_t N> reverse_iterator<T*> constexpr rend(T (&array)[N]);        // C++14
396template <class C> constexpr auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14
397template <class C> constexpr auto crend(const C& c) -> decltype(std::rend(c));          // C++14
398
399// 24.8, container access:
400template <class C> constexpr auto size(const C& c) -> decltype(c.size());         // C++17
401template <class T, size_t N> constexpr size_t size(const T (&array)[N]) noexcept; // C++17
402
403template <class C> constexpr auto ssize(const C& c)
404    -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>;				       // C++20
405template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
406
407template <class C> constexpr auto empty(const C& c) -> decltype(c.empty());       // C++17
408template <class T, size_t N> constexpr bool empty(const T (&array)[N]) noexcept;  // C++17
409template <class E> constexpr bool empty(initializer_list<E> il) noexcept;         // C++17
410template <class C> constexpr auto data(C& c) -> decltype(c.data());               // C++17
411template <class C> constexpr auto data(const C& c) -> decltype(c.data());         // C++17
412template <class T, size_t N> constexpr T* data(T (&array)[N]) noexcept;           // C++17
413template <class E> constexpr const E* data(initializer_list<E> il) noexcept;      // C++17
414
415}  // std
416
417*/
418
419#include <__config>
420#include <iosfwd> // for forward declarations of vector and string.
421#include <__functional_base>
422#include <type_traits>
423#include <cstddef>
424#include <initializer_list>
425#include <version>
426#ifdef __APPLE__
427#include <Availability.h>
428#endif
429
430#include <__debug>
431
432#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
433#pragma GCC system_header
434#endif
435
436_LIBCPP_BEGIN_NAMESPACE_STD
437template <class _Iter>
438struct _LIBCPP_TEMPLATE_VIS iterator_traits;
439
440struct _LIBCPP_TEMPLATE_VIS input_iterator_tag {};
441struct _LIBCPP_TEMPLATE_VIS output_iterator_tag {};
442struct _LIBCPP_TEMPLATE_VIS forward_iterator_tag       : public input_iterator_tag {};
443struct _LIBCPP_TEMPLATE_VIS bidirectional_iterator_tag : public forward_iterator_tag {};
444struct _LIBCPP_TEMPLATE_VIS random_access_iterator_tag : public bidirectional_iterator_tag {};
445#if _LIBCPP_STD_VER > 17
446// TODO(EricWF)  contiguous_iterator_tag is provided as an extension prior to
447//  C++20 to allow optimizations for users providing wrapped iterator types.
448struct _LIBCPP_TEMPLATE_VIS contiguous_iterator_tag: public random_access_iterator_tag { };
449#endif
450
451template <class _Iter>
452struct __iter_traits_cache {
453  using type = _If<
454    __is_primary_template<iterator_traits<_Iter> >::value,
455    _Iter,
456    iterator_traits<_Iter>
457  >;
458};
459template <class _Iter>
460using _ITER_TRAITS = typename __iter_traits_cache<_Iter>::type;
461
462struct __iter_concept_concept_test {
463  template <class _Iter>
464  using _Apply = typename _ITER_TRAITS<_Iter>::iterator_concept;
465};
466struct __iter_concept_category_test {
467  template <class _Iter>
468  using _Apply = typename _ITER_TRAITS<_Iter>::iterator_category;
469};
470struct __iter_concept_random_fallback {
471  template <class _Iter>
472  using _Apply = _EnableIf<
473                          __is_primary_template<iterator_traits<_Iter> >::value,
474                          random_access_iterator_tag
475                        >;
476};
477
478template <class _Iter, class _Tester> struct __test_iter_concept
479    : _IsValidExpansion<_Tester::template _Apply, _Iter>,
480      _Tester
481{
482};
483
484template <class _Iter>
485struct __iter_concept_cache {
486  using type = _Or<
487    __test_iter_concept<_Iter, __iter_concept_concept_test>,
488    __test_iter_concept<_Iter, __iter_concept_category_test>,
489    __test_iter_concept<_Iter, __iter_concept_random_fallback>
490  >;
491};
492
493template <class _Iter>
494using _ITER_CONCEPT = typename __iter_concept_cache<_Iter>::type::template _Apply<_Iter>;
495
496
497template <class _Tp>
498struct __has_iterator_typedefs
499{
500private:
501    struct __two {char __lx; char __lxx;};
502    template <class _Up> static __two __test(...);
503    template <class _Up> static char __test(typename std::__void_t<typename _Up::iterator_category>::type* = 0,
504    										typename std::__void_t<typename _Up::difference_type>::type* = 0,
505    										typename std::__void_t<typename _Up::value_type>::type* = 0,
506    										typename std::__void_t<typename _Up::reference>::type* = 0,
507    										typename std::__void_t<typename _Up::pointer>::type* = 0
508    										);
509public:
510    static const bool value = sizeof(__test<_Tp>(0,0,0,0,0)) == 1;
511};
512
513
514template <class _Tp>
515struct __has_iterator_category
516{
517private:
518    struct __two {char __lx; char __lxx;};
519    template <class _Up> static __two __test(...);
520    template <class _Up> static char __test(typename _Up::iterator_category* = 0);
521public:
522    static const bool value = sizeof(__test<_Tp>(0)) == 1;
523};
524
525template <class _Iter, bool> struct __iterator_traits_impl {};
526
527template <class _Iter>
528struct __iterator_traits_impl<_Iter, true>
529{
530    typedef typename _Iter::difference_type   difference_type;
531    typedef typename _Iter::value_type        value_type;
532    typedef typename _Iter::pointer           pointer;
533    typedef typename _Iter::reference         reference;
534    typedef typename _Iter::iterator_category iterator_category;
535};
536
537template <class _Iter, bool> struct __iterator_traits {};
538
539template <class _Iter>
540struct __iterator_traits<_Iter, true>
541    :  __iterator_traits_impl
542      <
543        _Iter,
544        is_convertible<typename _Iter::iterator_category, input_iterator_tag>::value ||
545        is_convertible<typename _Iter::iterator_category, output_iterator_tag>::value
546      >
547{};
548
549// iterator_traits<Iterator> will only have the nested types if Iterator::iterator_category
550//    exists.  Else iterator_traits<Iterator> will be an empty class.  This is a
551//    conforming extension which allows some programs to compile and behave as
552//    the client expects instead of failing at compile time.
553
554template <class _Iter>
555struct _LIBCPP_TEMPLATE_VIS iterator_traits
556    : __iterator_traits<_Iter, __has_iterator_typedefs<_Iter>::value> {
557
558  using __primary_template = iterator_traits;
559};
560
561template<class _Tp>
562struct _LIBCPP_TEMPLATE_VIS iterator_traits<_Tp*>
563{
564    typedef ptrdiff_t difference_type;
565    typedef typename remove_cv<_Tp>::type value_type;
566    typedef _Tp* pointer;
567    typedef _Tp& reference;
568    typedef random_access_iterator_tag iterator_category;
569#if _LIBCPP_STD_VER > 17
570    typedef contiguous_iterator_tag    iterator_concept;
571#endif
572};
573
574template <class _Tp, class _Up, bool = __has_iterator_category<iterator_traits<_Tp> >::value>
575struct __has_iterator_category_convertible_to
576    : public integral_constant<bool, is_convertible<typename iterator_traits<_Tp>::iterator_category, _Up>::value>
577{};
578
579template <class _Tp, class _Up>
580struct __has_iterator_category_convertible_to<_Tp, _Up, false> : public false_type {};
581
582template <class _Tp>
583struct __is_cpp17_input_iterator : public __has_iterator_category_convertible_to<_Tp, input_iterator_tag> {};
584
585template <class _Tp>
586struct __is_cpp17_forward_iterator : public __has_iterator_category_convertible_to<_Tp, forward_iterator_tag> {};
587
588template <class _Tp>
589struct __is_cpp17_bidirectional_iterator : public __has_iterator_category_convertible_to<_Tp, bidirectional_iterator_tag> {};
590
591template <class _Tp>
592struct __is_cpp17_random_access_iterator : public __has_iterator_category_convertible_to<_Tp, random_access_iterator_tag> {};
593
594#if _LIBCPP_STD_VER > 17
595template <class _Tp>
596struct __is_cpp17_contiguous_iterator : public __has_iterator_category_convertible_to<_Tp, contiguous_iterator_tag> {};
597#else
598template <class _Tp>
599struct __is_cpp17_contiguous_iterator : public false_type {};
600#endif
601
602
603template <class _Tp>
604struct __is_exactly_cpp17_input_iterator
605    : public integral_constant<bool,
606         __has_iterator_category_convertible_to<_Tp, input_iterator_tag>::value &&
607        !__has_iterator_category_convertible_to<_Tp, forward_iterator_tag>::value> {};
608
609#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
610template<class _InputIterator>
611using __iter_value_type = typename iterator_traits<_InputIterator>::value_type;
612
613template<class _InputIterator>
614using __iter_key_type = remove_const_t<typename iterator_traits<_InputIterator>::value_type::first_type>;
615
616template<class _InputIterator>
617using __iter_mapped_type = typename iterator_traits<_InputIterator>::value_type::second_type;
618
619template<class _InputIterator>
620using __iter_to_alloc_type = pair<
621    add_const_t<typename iterator_traits<_InputIterator>::value_type::first_type>,
622    typename iterator_traits<_InputIterator>::value_type::second_type>;
623#endif
624
625template<class _Category, class _Tp, class _Distance = ptrdiff_t,
626         class _Pointer = _Tp*, class _Reference = _Tp&>
627struct _LIBCPP_TEMPLATE_VIS iterator
628{
629    typedef _Tp        value_type;
630    typedef _Distance  difference_type;
631    typedef _Pointer   pointer;
632    typedef _Reference reference;
633    typedef _Category  iterator_category;
634};
635
636template <class _InputIter>
637inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
638void __advance(_InputIter& __i,
639             typename iterator_traits<_InputIter>::difference_type __n, input_iterator_tag)
640{
641    for (; __n > 0; --__n)
642        ++__i;
643}
644
645template <class _BiDirIter>
646inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
647void __advance(_BiDirIter& __i,
648             typename iterator_traits<_BiDirIter>::difference_type __n, bidirectional_iterator_tag)
649{
650    if (__n >= 0)
651        for (; __n > 0; --__n)
652            ++__i;
653    else
654        for (; __n < 0; ++__n)
655            --__i;
656}
657
658template <class _RandIter>
659inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
660void __advance(_RandIter& __i,
661             typename iterator_traits<_RandIter>::difference_type __n, random_access_iterator_tag)
662{
663   __i += __n;
664}
665
666template <class _InputIter>
667inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
668void advance(_InputIter& __i,
669             typename iterator_traits<_InputIter>::difference_type __n)
670{
671    _LIBCPP_ASSERT(__n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
672                       "Attempt to advance(it, -n) on a non-bidi iterator");
673    __advance(__i, __n, typename iterator_traits<_InputIter>::iterator_category());
674}
675
676template <class _InputIter>
677inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
678typename iterator_traits<_InputIter>::difference_type
679__distance(_InputIter __first, _InputIter __last, input_iterator_tag)
680{
681    typename iterator_traits<_InputIter>::difference_type __r(0);
682    for (; __first != __last; ++__first)
683        ++__r;
684    return __r;
685}
686
687template <class _RandIter>
688inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
689typename iterator_traits<_RandIter>::difference_type
690__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag)
691{
692    return __last - __first;
693}
694
695template <class _InputIter>
696inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
697typename iterator_traits<_InputIter>::difference_type
698distance(_InputIter __first, _InputIter __last)
699{
700    return __distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
701}
702
703template <class _InputIter>
704inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
705typename enable_if
706<
707    __is_cpp17_input_iterator<_InputIter>::value,
708    _InputIter
709>::type
710next(_InputIter __x,
711     typename iterator_traits<_InputIter>::difference_type __n = 1)
712{
713    _LIBCPP_ASSERT(__n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
714                       "Attempt to next(it, -n) on a non-bidi iterator");
715
716    _VSTD::advance(__x, __n);
717    return __x;
718}
719
720template <class _InputIter>
721inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
722typename enable_if
723<
724    __is_cpp17_input_iterator<_InputIter>::value,
725    _InputIter
726>::type
727prev(_InputIter __x,
728     typename iterator_traits<_InputIter>::difference_type __n = 1)
729{
730    _LIBCPP_ASSERT(__n <= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
731                       "Attempt to prev(it, +n) on a non-bidi iterator");
732    _VSTD::advance(__x, -__n);
733    return __x;
734}
735
736
737template <class _Tp, class = void>
738struct __is_stashing_iterator : false_type {};
739
740template <class _Tp>
741struct __is_stashing_iterator<_Tp, typename __void_t<typename _Tp::__stashing_iterator_tag>::type>
742  : true_type {};
743
744template <class _Iter>
745class _LIBCPP_TEMPLATE_VIS reverse_iterator
746    : public iterator<typename iterator_traits<_Iter>::iterator_category,
747                      typename iterator_traits<_Iter>::value_type,
748                      typename iterator_traits<_Iter>::difference_type,
749                      typename iterator_traits<_Iter>::pointer,
750                      typename iterator_traits<_Iter>::reference>
751{
752private:
753    /*mutable*/ _Iter __t;  // no longer used as of LWG #2360, not removed due to ABI break
754
755    static_assert(!__is_stashing_iterator<_Iter>::value,
756      "The specified iterator type cannot be used with reverse_iterator; "
757      "Using stashing iterators with reverse_iterator causes undefined behavior");
758
759protected:
760    _Iter current;
761public:
762    typedef _Iter                                            iterator_type;
763    typedef typename iterator_traits<_Iter>::difference_type difference_type;
764    typedef typename iterator_traits<_Iter>::reference       reference;
765    typedef typename iterator_traits<_Iter>::pointer         pointer;
766
767    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
768    reverse_iterator() : __t(), current() {}
769    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
770    explicit reverse_iterator(_Iter __x) : __t(__x), current(__x) {}
771    template <class _Up>
772        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
773        reverse_iterator(const reverse_iterator<_Up>& __u) : __t(__u.base()), current(__u.base()) {}
774    template <class _Up>
775        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
776        reverse_iterator& operator=(const reverse_iterator<_Up>& __u)
777            { __t = current = __u.base(); return *this; }
778    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
779    _Iter base() const {return current;}
780    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
781    reference operator*() const {_Iter __tmp = current; return *--__tmp;}
782    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
783    pointer  operator->() const {return _VSTD::addressof(operator*());}
784    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
785    reverse_iterator& operator++() {--current; return *this;}
786    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
787    reverse_iterator  operator++(int) {reverse_iterator __tmp(*this); --current; return __tmp;}
788    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
789    reverse_iterator& operator--() {++current; return *this;}
790    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
791    reverse_iterator  operator--(int) {reverse_iterator __tmp(*this); ++current; return __tmp;}
792    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
793    reverse_iterator  operator+ (difference_type __n) const {return reverse_iterator(current - __n);}
794    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
795    reverse_iterator& operator+=(difference_type __n) {current -= __n; return *this;}
796    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
797    reverse_iterator  operator- (difference_type __n) const {return reverse_iterator(current + __n);}
798    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
799    reverse_iterator& operator-=(difference_type __n) {current += __n; return *this;}
800    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
801    reference         operator[](difference_type __n) const {return *(*this + __n);}
802};
803
804template <class _Iter1, class _Iter2>
805inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
806bool
807operator==(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
808{
809    return __x.base() == __y.base();
810}
811
812template <class _Iter1, class _Iter2>
813inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
814bool
815operator<(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
816{
817    return __x.base() > __y.base();
818}
819
820template <class _Iter1, class _Iter2>
821inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
822bool
823operator!=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
824{
825    return __x.base() != __y.base();
826}
827
828template <class _Iter1, class _Iter2>
829inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
830bool
831operator>(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
832{
833    return __x.base() < __y.base();
834}
835
836template <class _Iter1, class _Iter2>
837inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
838bool
839operator>=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
840{
841    return __x.base() <= __y.base();
842}
843
844template <class _Iter1, class _Iter2>
845inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
846bool
847operator<=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
848{
849    return __x.base() >= __y.base();
850}
851
852#ifndef _LIBCPP_CXX03_LANG
853template <class _Iter1, class _Iter2>
854inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
855auto
856operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
857-> decltype(__y.base() - __x.base())
858{
859    return __y.base() - __x.base();
860}
861#else
862template <class _Iter1, class _Iter2>
863inline _LIBCPP_INLINE_VISIBILITY
864typename reverse_iterator<_Iter1>::difference_type
865operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
866{
867    return __y.base() - __x.base();
868}
869#endif
870
871template <class _Iter>
872inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
873reverse_iterator<_Iter>
874operator+(typename reverse_iterator<_Iter>::difference_type __n, const reverse_iterator<_Iter>& __x)
875{
876    return reverse_iterator<_Iter>(__x.base() - __n);
877}
878
879#if _LIBCPP_STD_VER > 11
880template <class _Iter>
881inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
882reverse_iterator<_Iter> make_reverse_iterator(_Iter __i)
883{
884    return reverse_iterator<_Iter>(__i);
885}
886#endif
887
888template <class _Container>
889class _LIBCPP_TEMPLATE_VIS back_insert_iterator
890    : public iterator<output_iterator_tag,
891                      void,
892                      void,
893                      void,
894                      void>
895{
896protected:
897    _Container* container;
898public:
899    typedef _Container container_type;
900
901    _LIBCPP_INLINE_VISIBILITY explicit back_insert_iterator(_Container& __x) : container(_VSTD::addressof(__x)) {}
902    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(const typename _Container::value_type& __value_)
903        {container->push_back(__value_); return *this;}
904#ifndef _LIBCPP_CXX03_LANG
905    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(typename _Container::value_type&& __value_)
906        {container->push_back(_VSTD::move(__value_)); return *this;}
907#endif  // _LIBCPP_CXX03_LANG
908    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator*()     {return *this;}
909    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator++()    {return *this;}
910    _LIBCPP_INLINE_VISIBILITY back_insert_iterator  operator++(int) {return *this;}
911};
912
913template <class _Container>
914inline _LIBCPP_INLINE_VISIBILITY
915back_insert_iterator<_Container>
916back_inserter(_Container& __x)
917{
918    return back_insert_iterator<_Container>(__x);
919}
920
921template <class _Container>
922class _LIBCPP_TEMPLATE_VIS front_insert_iterator
923    : public iterator<output_iterator_tag,
924                      void,
925                      void,
926                      void,
927                      void>
928{
929protected:
930    _Container* container;
931public:
932    typedef _Container container_type;
933
934    _LIBCPP_INLINE_VISIBILITY explicit front_insert_iterator(_Container& __x) : container(_VSTD::addressof(__x)) {}
935    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(const typename _Container::value_type& __value_)
936        {container->push_front(__value_); return *this;}
937#ifndef _LIBCPP_CXX03_LANG
938    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(typename _Container::value_type&& __value_)
939        {container->push_front(_VSTD::move(__value_)); return *this;}
940#endif  // _LIBCPP_CXX03_LANG
941    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator*()     {return *this;}
942    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator++()    {return *this;}
943    _LIBCPP_INLINE_VISIBILITY front_insert_iterator  operator++(int) {return *this;}
944};
945
946template <class _Container>
947inline _LIBCPP_INLINE_VISIBILITY
948front_insert_iterator<_Container>
949front_inserter(_Container& __x)
950{
951    return front_insert_iterator<_Container>(__x);
952}
953
954template <class _Container>
955class _LIBCPP_TEMPLATE_VIS insert_iterator
956    : public iterator<output_iterator_tag,
957                      void,
958                      void,
959                      void,
960                      void>
961{
962protected:
963    _Container* container;
964    typename _Container::iterator iter;
965public:
966    typedef _Container container_type;
967
968    _LIBCPP_INLINE_VISIBILITY insert_iterator(_Container& __x, typename _Container::iterator __i)
969        : container(_VSTD::addressof(__x)), iter(__i) {}
970    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(const typename _Container::value_type& __value_)
971        {iter = container->insert(iter, __value_); ++iter; return *this;}
972#ifndef _LIBCPP_CXX03_LANG
973    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(typename _Container::value_type&& __value_)
974        {iter = container->insert(iter, _VSTD::move(__value_)); ++iter; return *this;}
975#endif  // _LIBCPP_CXX03_LANG
976    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator*()        {return *this;}
977    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++()       {return *this;}
978    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++(int)    {return *this;}
979};
980
981template <class _Container>
982inline _LIBCPP_INLINE_VISIBILITY
983insert_iterator<_Container>
984inserter(_Container& __x, typename _Container::iterator __i)
985{
986    return insert_iterator<_Container>(__x, __i);
987}
988
989template <class _Tp, class _CharT = char,
990          class _Traits = char_traits<_CharT>, class _Distance = ptrdiff_t>
991class _LIBCPP_TEMPLATE_VIS istream_iterator
992    : public iterator<input_iterator_tag, _Tp, _Distance, const _Tp*, const _Tp&>
993{
994public:
995    typedef _CharT char_type;
996    typedef _Traits traits_type;
997    typedef basic_istream<_CharT,_Traits> istream_type;
998private:
999    istream_type* __in_stream_;
1000    _Tp __value_;
1001public:
1002    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(0), __value_() {}
1003    _LIBCPP_INLINE_VISIBILITY istream_iterator(istream_type& __s) : __in_stream_(_VSTD::addressof(__s))
1004        {
1005            if (!(*__in_stream_ >> __value_))
1006                __in_stream_ = 0;
1007        }
1008
1009    _LIBCPP_INLINE_VISIBILITY const _Tp& operator*() const {return __value_;}
1010    _LIBCPP_INLINE_VISIBILITY const _Tp* operator->() const {return _VSTD::addressof((operator*()));}
1011    _LIBCPP_INLINE_VISIBILITY istream_iterator& operator++()
1012        {
1013            if (!(*__in_stream_ >> __value_))
1014                __in_stream_ = 0;
1015            return *this;
1016        }
1017    _LIBCPP_INLINE_VISIBILITY istream_iterator  operator++(int)
1018        {istream_iterator __t(*this); ++(*this); return __t;}
1019
1020    template <class _Up, class _CharU, class _TraitsU, class _DistanceU>
1021    friend _LIBCPP_INLINE_VISIBILITY
1022    bool
1023    operator==(const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __x,
1024               const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __y);
1025
1026    template <class _Up, class _CharU, class _TraitsU, class _DistanceU>
1027    friend _LIBCPP_INLINE_VISIBILITY
1028    bool
1029    operator==(const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __x,
1030               const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __y);
1031};
1032
1033template <class _Tp, class _CharT, class _Traits, class _Distance>
1034inline _LIBCPP_INLINE_VISIBILITY
1035bool
1036operator==(const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __x,
1037           const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __y)
1038{
1039    return __x.__in_stream_ == __y.__in_stream_;
1040}
1041
1042template <class _Tp, class _CharT, class _Traits, class _Distance>
1043inline _LIBCPP_INLINE_VISIBILITY
1044bool
1045operator!=(const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __x,
1046           const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __y)
1047{
1048    return !(__x == __y);
1049}
1050
1051template <class _Tp, class _CharT = char, class _Traits = char_traits<_CharT> >
1052class _LIBCPP_TEMPLATE_VIS ostream_iterator
1053    : public iterator<output_iterator_tag, void, void, void, void>
1054{
1055public:
1056    typedef _CharT char_type;
1057    typedef _Traits traits_type;
1058    typedef basic_ostream<_CharT,_Traits> ostream_type;
1059private:
1060    ostream_type* __out_stream_;
1061    const char_type* __delim_;
1062public:
1063    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s) _NOEXCEPT
1064        : __out_stream_(_VSTD::addressof(__s)), __delim_(0) {}
1065    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s, const _CharT* __delimiter) _NOEXCEPT
1066        : __out_stream_(_VSTD::addressof(__s)), __delim_(__delimiter) {}
1067    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator=(const _Tp& __value_)
1068        {
1069            *__out_stream_ << __value_;
1070            if (__delim_)
1071                *__out_stream_ << __delim_;
1072            return *this;
1073        }
1074
1075    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator*()     {return *this;}
1076    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++()    {return *this;}
1077    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++(int) {return *this;}
1078};
1079
1080template<class _CharT, class _Traits>
1081class _LIBCPP_TEMPLATE_VIS istreambuf_iterator
1082    : public iterator<input_iterator_tag, _CharT,
1083                      typename _Traits::off_type, _CharT*,
1084                      _CharT>
1085{
1086public:
1087    typedef _CharT                          char_type;
1088    typedef _Traits                         traits_type;
1089    typedef typename _Traits::int_type      int_type;
1090    typedef basic_streambuf<_CharT,_Traits> streambuf_type;
1091    typedef basic_istream<_CharT,_Traits>   istream_type;
1092private:
1093    mutable streambuf_type* __sbuf_;
1094
1095    class __proxy
1096    {
1097        char_type __keep_;
1098        streambuf_type* __sbuf_;
1099        _LIBCPP_INLINE_VISIBILITY __proxy(char_type __c, streambuf_type* __s)
1100            : __keep_(__c), __sbuf_(__s) {}
1101        friend class istreambuf_iterator;
1102    public:
1103        _LIBCPP_INLINE_VISIBILITY char_type operator*() const {return __keep_;}
1104    };
1105
1106    _LIBCPP_INLINE_VISIBILITY
1107    bool __test_for_eof() const
1108    {
1109        if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
1110            __sbuf_ = 0;
1111        return __sbuf_ == 0;
1112    }
1113public:
1114    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(0) {}
1115    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) _NOEXCEPT
1116        : __sbuf_(__s.rdbuf()) {}
1117    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) _NOEXCEPT
1118        : __sbuf_(__s) {}
1119    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(const __proxy& __p) _NOEXCEPT
1120        : __sbuf_(__p.__sbuf_) {}
1121
1122    _LIBCPP_INLINE_VISIBILITY char_type  operator*() const
1123        {return static_cast<char_type>(__sbuf_->sgetc());}
1124    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator& operator++()
1125        {
1126            __sbuf_->sbumpc();
1127            return *this;
1128        }
1129    _LIBCPP_INLINE_VISIBILITY __proxy              operator++(int)
1130        {
1131            return __proxy(__sbuf_->sbumpc(), __sbuf_);
1132        }
1133
1134    _LIBCPP_INLINE_VISIBILITY bool equal(const istreambuf_iterator& __b) const
1135        {return __test_for_eof() == __b.__test_for_eof();}
1136};
1137
1138template <class _CharT, class _Traits>
1139inline _LIBCPP_INLINE_VISIBILITY
1140bool operator==(const istreambuf_iterator<_CharT,_Traits>& __a,
1141                const istreambuf_iterator<_CharT,_Traits>& __b)
1142                {return __a.equal(__b);}
1143
1144template <class _CharT, class _Traits>
1145inline _LIBCPP_INLINE_VISIBILITY
1146bool operator!=(const istreambuf_iterator<_CharT,_Traits>& __a,
1147                const istreambuf_iterator<_CharT,_Traits>& __b)
1148                {return !__a.equal(__b);}
1149
1150template <class _CharT, class _Traits>
1151class _LIBCPP_TEMPLATE_VIS ostreambuf_iterator
1152    : public iterator<output_iterator_tag, void, void, void, void>
1153{
1154public:
1155    typedef _CharT                          char_type;
1156    typedef _Traits                         traits_type;
1157    typedef basic_streambuf<_CharT,_Traits> streambuf_type;
1158    typedef basic_ostream<_CharT,_Traits>   ostream_type;
1159private:
1160    streambuf_type* __sbuf_;
1161public:
1162    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(ostream_type& __s) _NOEXCEPT
1163        : __sbuf_(__s.rdbuf()) {}
1164    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(streambuf_type* __s) _NOEXCEPT
1165        : __sbuf_(__s) {}
1166    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator=(_CharT __c)
1167        {
1168            if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
1169                __sbuf_ = 0;
1170            return *this;
1171        }
1172    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator*()     {return *this;}
1173    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
1174    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
1175    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == 0;}
1176
1177    template <class _Ch, class _Tr>
1178    friend
1179    _LIBCPP_HIDDEN
1180    ostreambuf_iterator<_Ch, _Tr>
1181    __pad_and_output(ostreambuf_iterator<_Ch, _Tr> __s,
1182                     const _Ch* __ob, const _Ch* __op, const _Ch* __oe,
1183                     ios_base& __iob, _Ch __fl);
1184};
1185
1186template <class _Iter>
1187class _LIBCPP_TEMPLATE_VIS move_iterator
1188{
1189private:
1190    _Iter __i;
1191public:
1192    typedef _Iter                                            iterator_type;
1193    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
1194    typedef typename iterator_traits<iterator_type>::value_type value_type;
1195    typedef typename iterator_traits<iterator_type>::difference_type difference_type;
1196    typedef iterator_type pointer;
1197#ifndef _LIBCPP_CXX03_LANG
1198    typedef typename iterator_traits<iterator_type>::reference __reference;
1199    typedef typename conditional<
1200            is_reference<__reference>::value,
1201            typename remove_reference<__reference>::type&&,
1202            __reference
1203        >::type reference;
1204#else
1205    typedef typename iterator_traits<iterator_type>::reference reference;
1206#endif
1207
1208    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1209    move_iterator() : __i() {}
1210    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1211    explicit move_iterator(_Iter __x) : __i(__x) {}
1212    template <class _Up>
1213      _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1214      move_iterator(const move_iterator<_Up>& __u) : __i(__u.base()) {}
1215    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 _Iter base() const {return __i;}
1216    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1217    reference operator*() const { return static_cast<reference>(*__i); }
1218    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1219    pointer  operator->() const { return __i;}
1220    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1221    move_iterator& operator++() {++__i; return *this;}
1222    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1223    move_iterator  operator++(int) {move_iterator __tmp(*this); ++__i; return __tmp;}
1224    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1225    move_iterator& operator--() {--__i; return *this;}
1226    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1227    move_iterator  operator--(int) {move_iterator __tmp(*this); --__i; return __tmp;}
1228    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1229    move_iterator  operator+ (difference_type __n) const {return move_iterator(__i + __n);}
1230    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1231    move_iterator& operator+=(difference_type __n) {__i += __n; return *this;}
1232    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1233    move_iterator  operator- (difference_type __n) const {return move_iterator(__i - __n);}
1234    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1235    move_iterator& operator-=(difference_type __n) {__i -= __n; return *this;}
1236    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1237    reference operator[](difference_type __n) const { return static_cast<reference>(__i[__n]); }
1238};
1239
1240template <class _Iter1, class _Iter2>
1241inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1242bool
1243operator==(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1244{
1245    return __x.base() == __y.base();
1246}
1247
1248template <class _Iter1, class _Iter2>
1249inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1250bool
1251operator<(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1252{
1253    return __x.base() < __y.base();
1254}
1255
1256template <class _Iter1, class _Iter2>
1257inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1258bool
1259operator!=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1260{
1261    return __x.base() != __y.base();
1262}
1263
1264template <class _Iter1, class _Iter2>
1265inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1266bool
1267operator>(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1268{
1269    return __x.base() > __y.base();
1270}
1271
1272template <class _Iter1, class _Iter2>
1273inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1274bool
1275operator>=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1276{
1277    return __x.base() >= __y.base();
1278}
1279
1280template <class _Iter1, class _Iter2>
1281inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1282bool
1283operator<=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1284{
1285    return __x.base() <= __y.base();
1286}
1287
1288#ifndef _LIBCPP_CXX03_LANG
1289template <class _Iter1, class _Iter2>
1290inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1291auto
1292operator-(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1293-> decltype(__x.base() - __y.base())
1294{
1295    return __x.base() - __y.base();
1296}
1297#else
1298template <class _Iter1, class _Iter2>
1299inline _LIBCPP_INLINE_VISIBILITY
1300typename move_iterator<_Iter1>::difference_type
1301operator-(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1302{
1303    return __x.base() - __y.base();
1304}
1305#endif
1306
1307template <class _Iter>
1308inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1309move_iterator<_Iter>
1310operator+(typename move_iterator<_Iter>::difference_type __n, const move_iterator<_Iter>& __x)
1311{
1312    return move_iterator<_Iter>(__x.base() + __n);
1313}
1314
1315template <class _Iter>
1316inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1317move_iterator<_Iter>
1318make_move_iterator(_Iter __i)
1319{
1320    return move_iterator<_Iter>(__i);
1321}
1322
1323// __wrap_iter
1324
1325template <class _Iter> class __wrap_iter;
1326
1327template <class _Iter1, class _Iter2>
1328_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1329bool
1330operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1331
1332template <class _Iter1, class _Iter2>
1333_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1334bool
1335operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1336
1337template <class _Iter1, class _Iter2>
1338_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1339bool
1340operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1341
1342template <class _Iter1, class _Iter2>
1343_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1344bool
1345operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1346
1347template <class _Iter1, class _Iter2>
1348_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1349bool
1350operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1351
1352template <class _Iter1, class _Iter2>
1353_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1354bool
1355operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1356
1357#ifndef _LIBCPP_CXX03_LANG
1358template <class _Iter1, class _Iter2>
1359_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1360auto
1361operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1362-> decltype(__x.base() - __y.base());
1363#else
1364template <class _Iter1, class _Iter2>
1365_LIBCPP_INLINE_VISIBILITY
1366typename __wrap_iter<_Iter1>::difference_type
1367operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1368#endif
1369
1370template <class _Iter>
1371_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1372__wrap_iter<_Iter>
1373operator+(typename __wrap_iter<_Iter>::difference_type, __wrap_iter<_Iter>) _NOEXCEPT;
1374
1375template <class _Ip, class _Op> _Op _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 copy(_Ip, _Ip, _Op);
1376template <class _B1, class _B2> _B2 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 copy_backward(_B1, _B1, _B2);
1377template <class _Ip, class _Op> _Op _LIBCPP_INLINE_VISIBILITY move(_Ip, _Ip, _Op);
1378template <class _B1, class _B2> _B2 _LIBCPP_INLINE_VISIBILITY move_backward(_B1, _B1, _B2);
1379
1380#if _LIBCPP_DEBUG_LEVEL < 2
1381
1382template <class _Tp>
1383_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1384typename enable_if
1385<
1386    is_trivially_copy_assignable<_Tp>::value,
1387    _Tp*
1388>::type
1389__unwrap_iter(__wrap_iter<_Tp*>);
1390
1391#else
1392
1393template <class _Tp>
1394inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1395typename enable_if
1396<
1397    is_trivially_copy_assignable<_Tp>::value,
1398    __wrap_iter<_Tp*>
1399>::type
1400__unwrap_iter(__wrap_iter<_Tp*> __i);
1401
1402#endif
1403
1404template <class _Iter>
1405class __wrap_iter
1406{
1407public:
1408    typedef _Iter                                                      iterator_type;
1409    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
1410    typedef typename iterator_traits<iterator_type>::value_type        value_type;
1411    typedef typename iterator_traits<iterator_type>::difference_type   difference_type;
1412    typedef typename iterator_traits<iterator_type>::pointer           pointer;
1413    typedef typename iterator_traits<iterator_type>::reference         reference;
1414private:
1415    iterator_type __i;
1416public:
1417    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter() _NOEXCEPT
1418#if _LIBCPP_STD_VER > 11
1419                : __i{}
1420#endif
1421    {
1422#if _LIBCPP_DEBUG_LEVEL >= 2
1423        __get_db()->__insert_i(this);
1424#endif
1425    }
1426    template <class _Up> _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1427        __wrap_iter(const __wrap_iter<_Up>& __u,
1428            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = 0) _NOEXCEPT
1429            : __i(__u.base())
1430    {
1431#if _LIBCPP_DEBUG_LEVEL >= 2
1432        __get_db()->__iterator_copy(this, &__u);
1433#endif
1434    }
1435#if _LIBCPP_DEBUG_LEVEL >= 2
1436    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1437    __wrap_iter(const __wrap_iter& __x)
1438        : __i(__x.base())
1439    {
1440        __get_db()->__iterator_copy(this, &__x);
1441    }
1442    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1443    __wrap_iter& operator=(const __wrap_iter& __x)
1444    {
1445        if (this != &__x)
1446        {
1447            __get_db()->__iterator_copy(this, &__x);
1448            __i = __x.__i;
1449        }
1450        return *this;
1451    }
1452    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1453    ~__wrap_iter()
1454    {
1455        __get_db()->__erase_i(this);
1456    }
1457#endif
1458    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG reference operator*() const _NOEXCEPT
1459    {
1460#if _LIBCPP_DEBUG_LEVEL >= 2
1461        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1462                       "Attempted to dereference a non-dereferenceable iterator");
1463#endif
1464        return *__i;
1465    }
1466    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG pointer  operator->() const _NOEXCEPT
1467    {
1468#if _LIBCPP_DEBUG_LEVEL >= 2
1469        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1470                       "Attempted to dereference a non-dereferenceable iterator");
1471#endif
1472        return (pointer)_VSTD::addressof(*__i);
1473    }
1474    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator++() _NOEXCEPT
1475    {
1476#if _LIBCPP_DEBUG_LEVEL >= 2
1477        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1478                       "Attempted to increment non-incrementable iterator");
1479#endif
1480        ++__i;
1481        return *this;
1482    }
1483    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator++(int) _NOEXCEPT
1484        {__wrap_iter __tmp(*this); ++(*this); return __tmp;}
1485
1486    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator--() _NOEXCEPT
1487    {
1488#if _LIBCPP_DEBUG_LEVEL >= 2
1489        _LIBCPP_ASSERT(__get_const_db()->__decrementable(this),
1490                       "Attempted to decrement non-decrementable iterator");
1491#endif
1492        --__i;
1493        return *this;
1494    }
1495    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator--(int) _NOEXCEPT
1496        {__wrap_iter __tmp(*this); --(*this); return __tmp;}
1497    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator+ (difference_type __n) const _NOEXCEPT
1498        {__wrap_iter __w(*this); __w += __n; return __w;}
1499    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator+=(difference_type __n) _NOEXCEPT
1500    {
1501#if _LIBCPP_DEBUG_LEVEL >= 2
1502        _LIBCPP_ASSERT(__get_const_db()->__addable(this, __n),
1503                   "Attempted to add/subtract iterator outside of valid range");
1504#endif
1505        __i += __n;
1506        return *this;
1507    }
1508    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator- (difference_type __n) const _NOEXCEPT
1509        {return *this + (-__n);}
1510    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator-=(difference_type __n) _NOEXCEPT
1511        {*this += -__n; return *this;}
1512    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG reference    operator[](difference_type __n) const _NOEXCEPT
1513    {
1514#if _LIBCPP_DEBUG_LEVEL >= 2
1515        _LIBCPP_ASSERT(__get_const_db()->__subscriptable(this, __n),
1516                   "Attempted to subscript iterator outside of valid range");
1517#endif
1518        return __i[__n];
1519    }
1520
1521    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG iterator_type base() const _NOEXCEPT {return __i;}
1522
1523private:
1524#if _LIBCPP_DEBUG_LEVEL >= 2
1525    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter(const void* __p, iterator_type __x) : __i(__x)
1526    {
1527        __get_db()->__insert_ic(this, __p);
1528    }
1529#else
1530    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter(iterator_type __x) _NOEXCEPT : __i(__x) {}
1531#endif
1532
1533    template <class _Up> friend class __wrap_iter;
1534    template <class _CharT, class _Traits, class _Alloc> friend class basic_string;
1535    template <class _Tp, class _Alloc> friend class _LIBCPP_TEMPLATE_VIS vector;
1536    template <class _Tp, size_t> friend class _LIBCPP_TEMPLATE_VIS span;
1537
1538    template <class _Iter1, class _Iter2>
1539    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1540    bool
1541    operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1542
1543    template <class _Iter1, class _Iter2>
1544    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1545    bool
1546    operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1547
1548    template <class _Iter1, class _Iter2>
1549    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1550    bool
1551    operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1552
1553    template <class _Iter1, class _Iter2>
1554    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1555    bool
1556    operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1557
1558    template <class _Iter1, class _Iter2>
1559    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1560    bool
1561    operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1562
1563    template <class _Iter1, class _Iter2>
1564    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1565    bool
1566    operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1567
1568#ifndef _LIBCPP_CXX03_LANG
1569    template <class _Iter1, class _Iter2>
1570    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1571    auto
1572    operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1573    -> decltype(__x.base() - __y.base());
1574#else
1575    template <class _Iter1, class _Iter2>
1576    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1577    typename __wrap_iter<_Iter1>::difference_type
1578    operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1579#endif
1580
1581    template <class _Iter1>
1582    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1583    __wrap_iter<_Iter1>
1584    operator+(typename __wrap_iter<_Iter1>::difference_type, __wrap_iter<_Iter1>) _NOEXCEPT;
1585
1586    template <class _Ip, class _Op> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _Op copy(_Ip, _Ip, _Op);
1587    template <class _B1, class _B2> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _B2 copy_backward(_B1, _B1, _B2);
1588    template <class _Ip, class _Op> friend _Op move(_Ip, _Ip, _Op);
1589    template <class _B1, class _B2> friend _B2 move_backward(_B1, _B1, _B2);
1590
1591#if _LIBCPP_DEBUG_LEVEL < 2
1592    template <class _Tp>
1593    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1594    typename enable_if
1595    <
1596        is_trivially_copy_assignable<_Tp>::value,
1597        _Tp*
1598    >::type
1599    __unwrap_iter(__wrap_iter<_Tp*>);
1600#else
1601  template <class _Tp>
1602  inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1603  typename enable_if
1604  <
1605      is_trivially_copy_assignable<_Tp>::value,
1606      __wrap_iter<_Tp*>
1607  >::type
1608  __unwrap_iter(__wrap_iter<_Tp*> __i);
1609#endif
1610};
1611
1612template <class _Iter1, class _Iter2>
1613inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1614bool
1615operator==(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1616{
1617    return __x.base() == __y.base();
1618}
1619
1620template <class _Iter1, class _Iter2>
1621inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1622bool
1623operator<(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1624{
1625#if _LIBCPP_DEBUG_LEVEL >= 2
1626    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1627                   "Attempted to compare incomparable iterators");
1628#endif
1629    return __x.base() < __y.base();
1630}
1631
1632template <class _Iter1, class _Iter2>
1633inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1634bool
1635operator!=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1636{
1637    return !(__x == __y);
1638}
1639
1640template <class _Iter1, class _Iter2>
1641inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1642bool
1643operator>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1644{
1645    return __y < __x;
1646}
1647
1648template <class _Iter1, class _Iter2>
1649inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1650bool
1651operator>=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1652{
1653    return !(__x < __y);
1654}
1655
1656template <class _Iter1, class _Iter2>
1657inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1658bool
1659operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1660{
1661    return !(__y < __x);
1662}
1663
1664template <class _Iter1>
1665inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1666bool
1667operator!=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1668{
1669    return !(__x == __y);
1670}
1671
1672template <class _Iter1>
1673inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1674bool
1675operator>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1676{
1677    return __y < __x;
1678}
1679
1680template <class _Iter1>
1681inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1682bool
1683operator>=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1684{
1685    return !(__x < __y);
1686}
1687
1688template <class _Iter1>
1689inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1690bool
1691operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1692{
1693    return !(__y < __x);
1694}
1695
1696#ifndef _LIBCPP_CXX03_LANG
1697template <class _Iter1, class _Iter2>
1698inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1699auto
1700operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1701-> decltype(__x.base() - __y.base())
1702{
1703#if _LIBCPP_DEBUG_LEVEL >= 2
1704    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1705                   "Attempted to subtract incompatible iterators");
1706#endif
1707    return __x.base() - __y.base();
1708}
1709#else
1710template <class _Iter1, class _Iter2>
1711inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1712typename __wrap_iter<_Iter1>::difference_type
1713operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1714{
1715#if _LIBCPP_DEBUG_LEVEL >= 2
1716    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1717                   "Attempted to subtract incompatible iterators");
1718#endif
1719    return __x.base() - __y.base();
1720}
1721#endif
1722
1723template <class _Iter>
1724inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1725__wrap_iter<_Iter>
1726operator+(typename __wrap_iter<_Iter>::difference_type __n,
1727          __wrap_iter<_Iter> __x) _NOEXCEPT
1728{
1729    __x += __n;
1730    return __x;
1731}
1732
1733template <class _Iter>
1734struct __libcpp_is_trivial_iterator
1735    : public _LIBCPP_BOOL_CONSTANT(is_pointer<_Iter>::value) {};
1736
1737template <class _Iter>
1738struct __libcpp_is_trivial_iterator<move_iterator<_Iter> >
1739    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1740
1741template <class _Iter>
1742struct __libcpp_is_trivial_iterator<reverse_iterator<_Iter> >
1743    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1744
1745template <class _Iter>
1746struct __libcpp_is_trivial_iterator<__wrap_iter<_Iter> >
1747    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1748
1749
1750template <class _Tp, size_t _Np>
1751_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1752_Tp*
1753begin(_Tp (&__array)[_Np])
1754{
1755    return __array;
1756}
1757
1758template <class _Tp, size_t _Np>
1759_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1760_Tp*
1761end(_Tp (&__array)[_Np])
1762{
1763    return __array + _Np;
1764}
1765
1766#if !defined(_LIBCPP_CXX03_LANG)
1767
1768template <class _Cp>
1769_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1770auto
1771begin(_Cp& __c) -> decltype(__c.begin())
1772{
1773    return __c.begin();
1774}
1775
1776template <class _Cp>
1777_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1778auto
1779begin(const _Cp& __c) -> decltype(__c.begin())
1780{
1781    return __c.begin();
1782}
1783
1784template <class _Cp>
1785_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1786auto
1787end(_Cp& __c) -> decltype(__c.end())
1788{
1789    return __c.end();
1790}
1791
1792template <class _Cp>
1793_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1794auto
1795end(const _Cp& __c) -> decltype(__c.end())
1796{
1797    return __c.end();
1798}
1799
1800#if _LIBCPP_STD_VER > 11
1801
1802template <class _Tp, size_t _Np>
1803_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1804reverse_iterator<_Tp*> rbegin(_Tp (&__array)[_Np])
1805{
1806    return reverse_iterator<_Tp*>(__array + _Np);
1807}
1808
1809template <class _Tp, size_t _Np>
1810_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1811reverse_iterator<_Tp*> rend(_Tp (&__array)[_Np])
1812{
1813    return reverse_iterator<_Tp*>(__array);
1814}
1815
1816template <class _Ep>
1817_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1818reverse_iterator<const _Ep*> rbegin(initializer_list<_Ep> __il)
1819{
1820    return reverse_iterator<const _Ep*>(__il.end());
1821}
1822
1823template <class _Ep>
1824_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1825reverse_iterator<const _Ep*> rend(initializer_list<_Ep> __il)
1826{
1827    return reverse_iterator<const _Ep*>(__il.begin());
1828}
1829
1830template <class _Cp>
1831_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1832auto cbegin(const _Cp& __c) -> decltype(_VSTD::begin(__c))
1833{
1834    return _VSTD::begin(__c);
1835}
1836
1837template <class _Cp>
1838_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1839auto cend(const _Cp& __c) -> decltype(_VSTD::end(__c))
1840{
1841    return _VSTD::end(__c);
1842}
1843
1844template <class _Cp>
1845_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1846auto rbegin(_Cp& __c) -> decltype(__c.rbegin())
1847{
1848    return __c.rbegin();
1849}
1850
1851template <class _Cp>
1852_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1853auto rbegin(const _Cp& __c) -> decltype(__c.rbegin())
1854{
1855    return __c.rbegin();
1856}
1857
1858template <class _Cp>
1859_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1860auto rend(_Cp& __c) -> decltype(__c.rend())
1861{
1862    return __c.rend();
1863}
1864
1865template <class _Cp>
1866_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1867auto rend(const _Cp& __c) -> decltype(__c.rend())
1868{
1869    return __c.rend();
1870}
1871
1872template <class _Cp>
1873_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1874auto crbegin(const _Cp& __c) -> decltype(_VSTD::rbegin(__c))
1875{
1876    return _VSTD::rbegin(__c);
1877}
1878
1879template <class _Cp>
1880_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1881auto crend(const _Cp& __c) -> decltype(_VSTD::rend(__c))
1882{
1883    return _VSTD::rend(__c);
1884}
1885
1886#endif
1887
1888
1889#else  // defined(_LIBCPP_CXX03_LANG)
1890
1891template <class _Cp>
1892_LIBCPP_INLINE_VISIBILITY
1893typename _Cp::iterator
1894begin(_Cp& __c)
1895{
1896    return __c.begin();
1897}
1898
1899template <class _Cp>
1900_LIBCPP_INLINE_VISIBILITY
1901typename _Cp::const_iterator
1902begin(const _Cp& __c)
1903{
1904    return __c.begin();
1905}
1906
1907template <class _Cp>
1908_LIBCPP_INLINE_VISIBILITY
1909typename _Cp::iterator
1910end(_Cp& __c)
1911{
1912    return __c.end();
1913}
1914
1915template <class _Cp>
1916_LIBCPP_INLINE_VISIBILITY
1917typename _Cp::const_iterator
1918end(const _Cp& __c)
1919{
1920    return __c.end();
1921}
1922
1923#endif  // !defined(_LIBCPP_CXX03_LANG)
1924
1925#if _LIBCPP_STD_VER > 14
1926
1927// #if _LIBCPP_STD_VER > 11
1928// template <>
1929// struct _LIBCPP_TEMPLATE_VIS plus<void>
1930// {
1931//     template <class _T1, class _T2>
1932//     _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1933//     auto operator()(_T1&& __t, _T2&& __u) const
1934//     _NOEXCEPT_(noexcept(_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u)))
1935//     -> decltype        (_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u))
1936//         { return        _VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u); }
1937//     typedef void is_transparent;
1938// };
1939// #endif
1940
1941template <class _Cont>
1942_LIBCPP_INLINE_VISIBILITY
1943constexpr auto size(const _Cont& __c)
1944_NOEXCEPT_(noexcept(__c.size()))
1945-> decltype        (__c.size())
1946{ return            __c.size(); }
1947
1948template <class _Tp, size_t _Sz>
1949_LIBCPP_INLINE_VISIBILITY
1950constexpr size_t size(const _Tp (&)[_Sz]) noexcept { return _Sz; }
1951
1952#if _LIBCPP_STD_VER > 17
1953template <class _Cont>
1954_LIBCPP_INLINE_VISIBILITY
1955constexpr auto ssize(const _Cont& __c)
1956_NOEXCEPT_(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size())))
1957->                              common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>
1958{ return            static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size()); }
1959
1960template <class _Tp, ptrdiff_t _Sz>
1961_LIBCPP_INLINE_VISIBILITY
1962constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept { return _Sz; }
1963#endif
1964
1965template <class _Cont>
1966_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
1967constexpr auto empty(const _Cont& __c)
1968_NOEXCEPT_(noexcept(__c.empty()))
1969-> decltype        (__c.empty())
1970{ return            __c.empty(); }
1971
1972template <class _Tp, size_t _Sz>
1973_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
1974constexpr bool empty(const _Tp (&)[_Sz]) noexcept { return false; }
1975
1976template <class _Ep>
1977_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
1978constexpr bool empty(initializer_list<_Ep> __il) noexcept { return __il.size() == 0; }
1979
1980template <class _Cont> constexpr
1981_LIBCPP_INLINE_VISIBILITY
1982auto data(_Cont& __c)
1983_NOEXCEPT_(noexcept(__c.data()))
1984-> decltype        (__c.data())
1985{ return            __c.data(); }
1986
1987template <class _Cont> constexpr
1988_LIBCPP_INLINE_VISIBILITY
1989auto data(const _Cont& __c)
1990_NOEXCEPT_(noexcept(__c.data()))
1991-> decltype        (__c.data())
1992{ return            __c.data(); }
1993
1994template <class _Tp, size_t _Sz>
1995_LIBCPP_INLINE_VISIBILITY
1996constexpr _Tp* data(_Tp (&__array)[_Sz]) noexcept { return __array; }
1997
1998template <class _Ep>
1999_LIBCPP_INLINE_VISIBILITY
2000constexpr const _Ep* data(initializer_list<_Ep> __il) noexcept { return __il.begin(); }
2001#endif
2002
2003
2004_LIBCPP_END_NAMESPACE_STD
2005
2006#endif  // _LIBCPP_ITERATOR
2007