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
57template <class InputIterator, class Distance>  // constexpr in C++17
58  constexpr void advance(InputIterator& i, Distance n);
59
60template <class InputIterator>  // constexpr in C++17
61  constexpr typename iterator_traits<InputIterator>::difference_type
62    distance(InputIterator first, InputIterator last);
63
64template <class InputIterator>  // constexpr in C++17
65  constexpr InputIterator next(InputIterator x,
66typename iterator_traits<InputIterator>::difference_type n = 1);
67
68template <class BidirectionalIterator>  // constexpr in C++17
69  constexpr BidirectionalIterator prev(BidirectionalIterator x,
70    typename iterator_traits<BidirectionalIterator>::difference_type n = 1);
71
72template <class Iterator>
73class reverse_iterator
74    : public iterator<typename iterator_traits<Iterator>::iterator_category,
75                      typename iterator_traits<Iterator>::value_type,
76                      typename iterator_traits<Iterator>::difference_type,
77                      typename iterator_traits<Iterator>::pointer,
78                      typename iterator_traits<Iterator>::reference>
79{
80protected:
81    Iterator current;
82public:
83    typedef Iterator                                            iterator_type;
84    typedef typename iterator_traits<Iterator>::difference_type difference_type;
85    typedef typename iterator_traits<Iterator>::reference       reference;
86    typedef typename iterator_traits<Iterator>::pointer         pointer;
87
88    constexpr reverse_iterator();
89    constexpr explicit reverse_iterator(Iterator x);
90    template <class U> constexpr reverse_iterator(const reverse_iterator<U>& u);
91    template <class U> constexpr reverse_iterator& operator=(const reverse_iterator<U>& u);
92    constexpr Iterator base() const;
93    constexpr reference operator*() const;
94    constexpr pointer   operator->() const;
95    constexpr reverse_iterator& operator++();
96    constexpr reverse_iterator  operator++(int);
97    constexpr reverse_iterator& operator--();
98    constexpr reverse_iterator  operator--(int);
99    constexpr reverse_iterator  operator+ (difference_type n) const;
100    constexpr reverse_iterator& operator+=(difference_type n);
101    constexpr reverse_iterator  operator- (difference_type n) const;
102    constexpr reverse_iterator& operator-=(difference_type n);
103    constexpr reference         operator[](difference_type n) const;
104};
105
106template <class Iterator1, class Iterator2>
107constexpr bool                          // constexpr in C++17
108operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
109
110template <class Iterator1, class Iterator2>
111constexpr bool                          // constexpr in C++17
112operator<(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
113
114template <class Iterator1, class Iterator2>
115constexpr bool                          // constexpr in C++17
116operator!=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
117
118template <class Iterator1, class Iterator2>
119constexpr bool                          // constexpr in C++17
120operator>(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
121
122template <class Iterator1, class Iterator2>
123constexpr bool                          // constexpr in C++17
124operator>=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
125
126template <class Iterator1, class Iterator2>
127constexpr bool                          // constexpr in C++17
128operator<=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
129
130template <class Iterator1, class Iterator2>
131constexpr auto
132operator-(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y)
133-> decltype(__y.base() - __x.base());   // constexpr in C++17
134
135template <class Iterator>
136constexpr reverse_iterator<Iterator>
137operator+(typename reverse_iterator<Iterator>::difference_type n,
138          const reverse_iterator<Iterator>& x);   // constexpr in C++17
139
140template <class Iterator>
141constexpr reverse_iterator<Iterator> make_reverse_iterator(Iterator i); // C++14, constexpr in C++17
142
143template <class Container>
144class back_insert_iterator
145{
146protected:
147    Container* container;
148public:
149    typedef Container                   container_type;
150    typedef void                        value_type;
151    typedef void                        difference_type;
152    typedef void                        reference;
153    typedef void                        pointer;
154
155    explicit back_insert_iterator(Container& x);
156    back_insert_iterator& operator=(const typename Container::value_type& value);
157    back_insert_iterator& operator*();
158    back_insert_iterator& operator++();
159    back_insert_iterator  operator++(int);
160};
161
162template <class Container> back_insert_iterator<Container> back_inserter(Container& x);
163
164template <class Container>
165class front_insert_iterator
166{
167protected:
168    Container* container;
169public:
170    typedef Container                    container_type;
171    typedef void                         value_type;
172    typedef void                         difference_type;
173    typedef void                         reference;
174    typedef void                         pointer;
175
176    explicit front_insert_iterator(Container& x);
177    front_insert_iterator& operator=(const typename Container::value_type& value);
178    front_insert_iterator& operator*();
179    front_insert_iterator& operator++();
180    front_insert_iterator  operator++(int);
181};
182
183template <class Container> front_insert_iterator<Container> front_inserter(Container& x);
184
185template <class Container>
186class insert_iterator
187{
188protected:
189    Container* container;
190    typename Container::iterator iter;
191public:
192    typedef Container              container_type;
193    typedef void                   value_type;
194    typedef void                   difference_type;
195    typedef void                   reference;
196    typedef void                   pointer;
197
198    insert_iterator(Container& x, typename Container::iterator i);
199    insert_iterator& operator=(const typename Container::value_type& value);
200    insert_iterator& operator*();
201    insert_iterator& operator++();
202    insert_iterator& operator++(int);
203};
204
205template <class Container, class Iterator>
206insert_iterator<Container> inserter(Container& x, Iterator i);
207
208template <class Iterator>
209class move_iterator {
210public:
211    typedef Iterator                                              iterator_type;
212    typedef typename iterator_traits<Iterator>::difference_type   difference_type;
213    typedef Iterator                                              pointer;
214    typedef typename iterator_traits<Iterator>::value_type        value_type;
215    typedef typename iterator_traits<Iterator>::iterator_category iterator_category;
216    typedef value_type&&                                          reference;
217
218    constexpr move_iterator();  // all the constexprs are in C++17
219    constexpr explicit move_iterator(Iterator i);
220    template <class U>
221      constexpr move_iterator(const move_iterator<U>& u);
222    template <class U>
223      constexpr move_iterator& operator=(const move_iterator<U>& u);
224    constexpr iterator_type base() const;
225    constexpr reference operator*() const;
226    constexpr pointer operator->() const;
227    constexpr move_iterator& operator++();
228    constexpr move_iterator operator++(int);
229    constexpr move_iterator& operator--();
230    constexpr move_iterator operator--(int);
231    constexpr move_iterator operator+(difference_type n) const;
232    constexpr move_iterator& operator+=(difference_type n);
233    constexpr move_iterator operator-(difference_type n) const;
234    constexpr move_iterator& operator-=(difference_type n);
235    constexpr unspecified operator[](difference_type n) const;
236private:
237    Iterator current; // exposition only
238};
239
240template <class Iterator1, class Iterator2>
241constexpr bool   // constexpr in C++17
242operator==(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
243
244template <class Iterator1, class Iterator2>
245constexpr bool   // constexpr in C++17
246operator!=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
247
248template <class Iterator1, class Iterator2>
249constexpr bool   // constexpr in C++17
250operator<(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
251
252template <class Iterator1, class Iterator2>
253constexpr bool   // constexpr in C++17
254operator<=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
255
256template <class Iterator1, class Iterator2>
257constexpr bool   // constexpr in C++17
258operator>(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
259
260template <class Iterator1, class Iterator2>
261constexpr bool   // constexpr in C++17
262operator>=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
263
264template <class Iterator1, class Iterator2>
265constexpr auto   // constexpr in C++17
266operator-(const move_iterator<Iterator1>& x,
267          const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
268
269template <class Iterator>
270constexpr move_iterator<Iterator> operator+(   // constexpr in C++17
271            typename move_iterator<Iterator>::difference_type n,
272            const move_iterator<Iterator>& x);
273
274template <class Iterator>   // constexpr in C++17
275constexpr  move_iterator<Iterator> make_move_iterator(const Iterator& i);
276
277
278template <class T, class charT = char, class traits = char_traits<charT>, class Distance = ptrdiff_t>
279class istream_iterator
280    : public iterator<input_iterator_tag, T, Distance, const T*, const T&>
281{
282public:
283    typedef charT char_type;
284    typedef traits traits_type;
285    typedef basic_istream<charT,traits> istream_type;
286
287    constexpr istream_iterator();
288    istream_iterator(istream_type& s);
289    istream_iterator(const istream_iterator& x);
290    ~istream_iterator();
291
292    const T& operator*() const;
293    const T* operator->() const;
294    istream_iterator& operator++();
295    istream_iterator  operator++(int);
296};
297
298template <class T, class charT, class traits, class Distance>
299bool operator==(const istream_iterator<T,charT,traits,Distance>& x,
300                const istream_iterator<T,charT,traits,Distance>& y);
301template <class T, class charT, class traits, class Distance>
302bool operator!=(const istream_iterator<T,charT,traits,Distance>& x,
303                const istream_iterator<T,charT,traits,Distance>& y);
304
305template <class T, class charT = char, class traits = char_traits<charT> >
306class ostream_iterator
307    : public iterator<output_iterator_tag, void, void, void ,void>
308{
309public:
310    typedef charT char_type;
311    typedef traits traits_type;
312    typedef basic_ostream<charT,traits> ostream_type;
313
314    ostream_iterator(ostream_type& s);
315    ostream_iterator(ostream_type& s, const charT* delimiter);
316    ostream_iterator(const ostream_iterator& x);
317    ~ostream_iterator();
318    ostream_iterator& operator=(const T& value);
319
320    ostream_iterator& operator*();
321    ostream_iterator& operator++();
322    ostream_iterator& operator++(int);
323};
324
325template<class charT, class traits = char_traits<charT> >
326class istreambuf_iterator
327    : public iterator<input_iterator_tag, charT,
328                      typename traits::off_type, unspecified,
329                      charT>
330{
331public:
332    typedef charT                         char_type;
333    typedef traits                        traits_type;
334    typedef typename traits::int_type     int_type;
335    typedef basic_streambuf<charT,traits> streambuf_type;
336    typedef basic_istream<charT,traits>   istream_type;
337
338    istreambuf_iterator() noexcept;
339    istreambuf_iterator(istream_type& s) noexcept;
340    istreambuf_iterator(streambuf_type* s) noexcept;
341    istreambuf_iterator(a-private-type) noexcept;
342
343    charT                operator*() const;
344    pointer operator->() const;
345    istreambuf_iterator& operator++();
346    a-private-type       operator++(int);
347
348    bool equal(const istreambuf_iterator& b) const;
349};
350
351template <class charT, class traits>
352bool operator==(const istreambuf_iterator<charT,traits>& a,
353                const istreambuf_iterator<charT,traits>& b);
354template <class charT, class traits>
355bool operator!=(const istreambuf_iterator<charT,traits>& a,
356                const istreambuf_iterator<charT,traits>& b);
357
358template <class charT, class traits = char_traits<charT> >
359class ostreambuf_iterator
360    : public iterator<output_iterator_tag, void, void, void, void>
361{
362public:
363    typedef charT                         char_type;
364    typedef traits                        traits_type;
365    typedef basic_streambuf<charT,traits> streambuf_type;
366    typedef basic_ostream<charT,traits>   ostream_type;
367
368    ostreambuf_iterator(ostream_type& s) noexcept;
369    ostreambuf_iterator(streambuf_type* s) noexcept;
370    ostreambuf_iterator& operator=(charT c);
371    ostreambuf_iterator& operator*();
372    ostreambuf_iterator& operator++();
373    ostreambuf_iterator& operator++(int);
374    bool failed() const noexcept;
375};
376
377template <class C> constexpr auto begin(C& c) -> decltype(c.begin());
378template <class C> constexpr auto begin(const C& c) -> decltype(c.begin());
379template <class C> constexpr auto end(C& c) -> decltype(c.end());
380template <class C> constexpr auto end(const C& c) -> decltype(c.end());
381template <class T, size_t N> constexpr T* begin(T (&array)[N]);
382template <class T, size_t N> constexpr T* end(T (&array)[N]);
383
384template <class C> auto constexpr cbegin(const C& c) -> decltype(std::begin(c));        // C++14
385template <class C> auto constexpr cend(const C& c) -> decltype(std::end(c));            // C++14
386template <class C> auto constexpr rbegin(C& c) -> decltype(c.rbegin());                 // C++14
387template <class C> auto constexpr rbegin(const C& c) -> decltype(c.rbegin());           // C++14
388template <class C> auto constexpr rend(C& c) -> decltype(c.rend());                     // C++14
389template <class C> constexpr auto rend(const C& c) -> decltype(c.rend());               // C++14
390template <class E> reverse_iterator<const E*> constexpr rbegin(initializer_list<E> il); // C++14
391template <class E> reverse_iterator<const E*> constexpr rend(initializer_list<E> il);   // C++14
392template <class T, size_t N> reverse_iterator<T*> constexpr rbegin(T (&array)[N]);      // C++14
393template <class T, size_t N> reverse_iterator<T*> constexpr rend(T (&array)[N]);        // C++14
394template <class C> constexpr auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14
395template <class C> constexpr auto crend(const C& c) -> decltype(std::rend(c));          // C++14
396
397// 24.8, container access:
398template <class C> constexpr auto size(const C& c) -> decltype(c.size());         // C++17
399template <class T, size_t N> constexpr size_t size(const T (&array)[N]) noexcept; // C++17
400
401template <class C> constexpr auto ssize(const C& c)
402    -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>;				       // C++20
403template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
404
405template <class C> constexpr auto empty(const C& c) -> decltype(c.empty());       // C++17
406template <class T, size_t N> constexpr bool empty(const T (&array)[N]) noexcept;  // C++17
407template <class E> constexpr bool empty(initializer_list<E> il) noexcept;         // C++17
408template <class C> constexpr auto data(C& c) -> decltype(c.data());               // C++17
409template <class C> constexpr auto data(const C& c) -> decltype(c.data());         // C++17
410template <class T, size_t N> constexpr T* data(T (&array)[N]) noexcept;           // C++17
411template <class E> constexpr const E* data(initializer_list<E> il) noexcept;      // C++17
412
413}  // std
414
415*/
416
417#include <__config>
418#include <iosfwd> // for forward declarations of vector and string.
419#include <__functional_base>
420#include <type_traits>
421#include <cstddef>
422#include <initializer_list>
423#include <__memory/base.h>
424#include <__memory/pointer_traits.h>
425#include <version>
426
427#include <__debug>
428
429#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
430#pragma GCC system_header
431#endif
432
433_LIBCPP_BEGIN_NAMESPACE_STD
434template <class _Iter>
435struct _LIBCPP_TEMPLATE_VIS iterator_traits;
436
437struct _LIBCPP_TEMPLATE_VIS input_iterator_tag {};
438struct _LIBCPP_TEMPLATE_VIS output_iterator_tag {};
439struct _LIBCPP_TEMPLATE_VIS forward_iterator_tag       : public input_iterator_tag {};
440struct _LIBCPP_TEMPLATE_VIS bidirectional_iterator_tag : public forward_iterator_tag {};
441struct _LIBCPP_TEMPLATE_VIS random_access_iterator_tag : public bidirectional_iterator_tag {};
442#if _LIBCPP_STD_VER > 17
443struct _LIBCPP_TEMPLATE_VIS contiguous_iterator_tag    : public random_access_iterator_tag {};
444#endif
445
446template <class _Iter>
447struct __iter_traits_cache {
448  using type = _If<
449    __is_primary_template<iterator_traits<_Iter> >::value,
450    _Iter,
451    iterator_traits<_Iter>
452  >;
453};
454template <class _Iter>
455using _ITER_TRAITS = typename __iter_traits_cache<_Iter>::type;
456
457struct __iter_concept_concept_test {
458  template <class _Iter>
459  using _Apply = typename _ITER_TRAITS<_Iter>::iterator_concept;
460};
461struct __iter_concept_category_test {
462  template <class _Iter>
463  using _Apply = typename _ITER_TRAITS<_Iter>::iterator_category;
464};
465struct __iter_concept_random_fallback {
466  template <class _Iter>
467  using _Apply = _EnableIf<
468                          __is_primary_template<iterator_traits<_Iter> >::value,
469                          random_access_iterator_tag
470                        >;
471};
472
473template <class _Iter, class _Tester> struct __test_iter_concept
474    : _IsValidExpansion<_Tester::template _Apply, _Iter>,
475      _Tester
476{
477};
478
479template <class _Iter>
480struct __iter_concept_cache {
481  using type = _Or<
482    __test_iter_concept<_Iter, __iter_concept_concept_test>,
483    __test_iter_concept<_Iter, __iter_concept_category_test>,
484    __test_iter_concept<_Iter, __iter_concept_random_fallback>
485  >;
486};
487
488template <class _Iter>
489using _ITER_CONCEPT = typename __iter_concept_cache<_Iter>::type::template _Apply<_Iter>;
490
491
492template <class _Tp>
493struct __has_iterator_typedefs
494{
495private:
496    struct __two {char __lx; char __lxx;};
497    template <class _Up> static __two __test(...);
498    template <class _Up> static char __test(typename __void_t<typename _Up::iterator_category>::type* = 0,
499                                            typename __void_t<typename _Up::difference_type>::type* = 0,
500                                            typename __void_t<typename _Up::value_type>::type* = 0,
501                                            typename __void_t<typename _Up::reference>::type* = 0,
502                                            typename __void_t<typename _Up::pointer>::type* = 0);
503public:
504    static const bool value = sizeof(__test<_Tp>(0,0,0,0,0)) == 1;
505};
506
507
508template <class _Tp>
509struct __has_iterator_category
510{
511private:
512    struct __two {char __lx; char __lxx;};
513    template <class _Up> static __two __test(...);
514    template <class _Up> static char __test(typename _Up::iterator_category* = nullptr);
515public:
516    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
517};
518
519template <class _Tp>
520struct __has_iterator_concept
521{
522private:
523    struct __two {char __lx; char __lxx;};
524    template <class _Up> static __two __test(...);
525    template <class _Up> static char __test(typename _Up::iterator_concept* = nullptr);
526public:
527    static const bool value = sizeof(__test<_Tp>(nullptr)) == 1;
528};
529
530template <class _Iter, bool> struct __iterator_traits_impl {};
531
532template <class _Iter>
533struct __iterator_traits_impl<_Iter, true>
534{
535    typedef typename _Iter::difference_type   difference_type;
536    typedef typename _Iter::value_type        value_type;
537    typedef typename _Iter::pointer           pointer;
538    typedef typename _Iter::reference         reference;
539    typedef typename _Iter::iterator_category iterator_category;
540};
541
542template <class _Iter, bool> struct __iterator_traits {};
543
544template <class _Iter>
545struct __iterator_traits<_Iter, true>
546    :  __iterator_traits_impl
547      <
548        _Iter,
549        is_convertible<typename _Iter::iterator_category, input_iterator_tag>::value ||
550        is_convertible<typename _Iter::iterator_category, output_iterator_tag>::value
551      >
552{};
553
554// iterator_traits<Iterator> will only have the nested types if Iterator::iterator_category
555//    exists.  Else iterator_traits<Iterator> will be an empty class.  This is a
556//    conforming extension which allows some programs to compile and behave as
557//    the client expects instead of failing at compile time.
558
559template <class _Iter>
560struct _LIBCPP_TEMPLATE_VIS iterator_traits
561    : __iterator_traits<_Iter, __has_iterator_typedefs<_Iter>::value> {
562
563  using __primary_template = iterator_traits;
564};
565
566template<class _Tp>
567struct _LIBCPP_TEMPLATE_VIS iterator_traits<_Tp*>
568{
569    typedef ptrdiff_t difference_type;
570    typedef typename remove_cv<_Tp>::type value_type;
571    typedef _Tp* pointer;
572    typedef _Tp& reference;
573    typedef random_access_iterator_tag iterator_category;
574#if _LIBCPP_STD_VER > 17
575    typedef contiguous_iterator_tag    iterator_concept;
576#endif
577};
578
579template <class _Tp, class _Up, bool = __has_iterator_category<iterator_traits<_Tp> >::value>
580struct __has_iterator_category_convertible_to
581    : _BoolConstant<is_convertible<typename iterator_traits<_Tp>::iterator_category, _Up>::value>
582{};
583
584template <class _Tp, class _Up>
585struct __has_iterator_category_convertible_to<_Tp, _Up, false> : false_type {};
586
587template <class _Tp, class _Up, bool = __has_iterator_concept<_Tp>::value>
588struct __has_iterator_concept_convertible_to
589    : _BoolConstant<is_convertible<typename _Tp::iterator_concept, _Up>::value>
590{};
591
592template <class _Tp, class _Up>
593struct __has_iterator_concept_convertible_to<_Tp, _Up, false> : false_type {};
594
595template <class _Tp>
596struct __is_cpp17_input_iterator : public __has_iterator_category_convertible_to<_Tp, input_iterator_tag> {};
597
598template <class _Tp>
599struct __is_cpp17_forward_iterator : public __has_iterator_category_convertible_to<_Tp, forward_iterator_tag> {};
600
601template <class _Tp>
602struct __is_cpp17_bidirectional_iterator : public __has_iterator_category_convertible_to<_Tp, bidirectional_iterator_tag> {};
603
604template <class _Tp>
605struct __is_cpp17_random_access_iterator : public __has_iterator_category_convertible_to<_Tp, random_access_iterator_tag> {};
606
607// __is_cpp17_contiguous_iterator determines if an iterator is contiguous,
608// either because it advertises itself as such (in C++20) or because it
609// is a pointer type or a known trivial wrapper around a pointer type,
610// such as __wrap_iter<T*>.
611//
612#if _LIBCPP_STD_VER > 17
613template <class _Tp>
614struct __is_cpp17_contiguous_iterator : _Or<
615    __has_iterator_category_convertible_to<_Tp, contiguous_iterator_tag>,
616    __has_iterator_concept_convertible_to<_Tp, contiguous_iterator_tag>
617> {};
618#else
619template <class _Tp>
620struct __is_cpp17_contiguous_iterator : false_type {};
621#endif
622
623// Any native pointer which is an iterator is also a contiguous iterator.
624template <class _Up>
625struct __is_cpp17_contiguous_iterator<_Up*> : true_type {};
626
627
628template <class _Tp>
629struct __is_exactly_cpp17_input_iterator
630    : public integral_constant<bool,
631         __has_iterator_category_convertible_to<_Tp, input_iterator_tag>::value &&
632        !__has_iterator_category_convertible_to<_Tp, forward_iterator_tag>::value> {};
633
634#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
635template<class _InputIterator>
636using __iter_value_type = typename iterator_traits<_InputIterator>::value_type;
637
638template<class _InputIterator>
639using __iter_key_type = remove_const_t<typename iterator_traits<_InputIterator>::value_type::first_type>;
640
641template<class _InputIterator>
642using __iter_mapped_type = typename iterator_traits<_InputIterator>::value_type::second_type;
643
644template<class _InputIterator>
645using __iter_to_alloc_type = pair<
646    add_const_t<typename iterator_traits<_InputIterator>::value_type::first_type>,
647    typename iterator_traits<_InputIterator>::value_type::second_type>;
648#endif
649
650template<class _Category, class _Tp, class _Distance = ptrdiff_t,
651         class _Pointer = _Tp*, class _Reference = _Tp&>
652struct _LIBCPP_TEMPLATE_VIS iterator
653{
654    typedef _Tp        value_type;
655    typedef _Distance  difference_type;
656    typedef _Pointer   pointer;
657    typedef _Reference reference;
658    typedef _Category  iterator_category;
659};
660
661template <class _InputIter>
662inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
663void __advance(_InputIter& __i,
664             typename iterator_traits<_InputIter>::difference_type __n, input_iterator_tag)
665{
666    for (; __n > 0; --__n)
667        ++__i;
668}
669
670template <class _BiDirIter>
671inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
672void __advance(_BiDirIter& __i,
673             typename iterator_traits<_BiDirIter>::difference_type __n, bidirectional_iterator_tag)
674{
675    if (__n >= 0)
676        for (; __n > 0; --__n)
677            ++__i;
678    else
679        for (; __n < 0; ++__n)
680            --__i;
681}
682
683template <class _RandIter>
684inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
685void __advance(_RandIter& __i,
686             typename iterator_traits<_RandIter>::difference_type __n, random_access_iterator_tag)
687{
688   __i += __n;
689}
690
691template <class _InputIter, class _Distance>
692inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
693void advance(_InputIter& __i, _Distance __orig_n)
694{
695    _LIBCPP_ASSERT(__orig_n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
696                   "Attempt to advance(it, n) with negative n on a non-bidirectional iterator");
697    typedef decltype(_VSTD::__convert_to_integral(__orig_n)) _IntegralSize;
698    _IntegralSize __n = __orig_n;
699    _VSTD::__advance(__i, __n, typename iterator_traits<_InputIter>::iterator_category());
700}
701
702template <class _InputIter>
703inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
704typename iterator_traits<_InputIter>::difference_type
705__distance(_InputIter __first, _InputIter __last, input_iterator_tag)
706{
707    typename iterator_traits<_InputIter>::difference_type __r(0);
708    for (; __first != __last; ++__first)
709        ++__r;
710    return __r;
711}
712
713template <class _RandIter>
714inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
715typename iterator_traits<_RandIter>::difference_type
716__distance(_RandIter __first, _RandIter __last, random_access_iterator_tag)
717{
718    return __last - __first;
719}
720
721template <class _InputIter>
722inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
723typename iterator_traits<_InputIter>::difference_type
724distance(_InputIter __first, _InputIter __last)
725{
726    return _VSTD::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
727}
728
729template <class _InputIter>
730inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
731typename enable_if
732<
733    __is_cpp17_input_iterator<_InputIter>::value,
734    _InputIter
735>::type
736next(_InputIter __x,
737     typename iterator_traits<_InputIter>::difference_type __n = 1)
738{
739    _LIBCPP_ASSERT(__n >= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
740                       "Attempt to next(it, n) with negative n on a non-bidirectional iterator");
741
742    _VSTD::advance(__x, __n);
743    return __x;
744}
745
746template <class _InputIter>
747inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
748typename enable_if
749<
750    __is_cpp17_input_iterator<_InputIter>::value,
751    _InputIter
752>::type
753prev(_InputIter __x,
754     typename iterator_traits<_InputIter>::difference_type __n = 1)
755{
756    _LIBCPP_ASSERT(__n <= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value,
757                       "Attempt to prev(it, n) with a positive n on a non-bidirectional iterator");
758    _VSTD::advance(__x, -__n);
759    return __x;
760}
761
762
763template <class _Tp, class = void>
764struct __is_stashing_iterator : false_type {};
765
766template <class _Tp>
767struct __is_stashing_iterator<_Tp, typename __void_t<typename _Tp::__stashing_iterator_tag>::type>
768  : true_type {};
769
770template <class _Iter>
771class _LIBCPP_TEMPLATE_VIS reverse_iterator
772    : public iterator<typename iterator_traits<_Iter>::iterator_category,
773                      typename iterator_traits<_Iter>::value_type,
774                      typename iterator_traits<_Iter>::difference_type,
775                      typename iterator_traits<_Iter>::pointer,
776                      typename iterator_traits<_Iter>::reference>
777{
778private:
779    /*mutable*/ _Iter __t;  // no longer used as of LWG #2360, not removed due to ABI break
780
781    static_assert(!__is_stashing_iterator<_Iter>::value,
782      "The specified iterator type cannot be used with reverse_iterator; "
783      "Using stashing iterators with reverse_iterator causes undefined behavior");
784
785protected:
786    _Iter current;
787public:
788    typedef _Iter                                            iterator_type;
789    typedef typename iterator_traits<_Iter>::difference_type difference_type;
790    typedef typename iterator_traits<_Iter>::reference       reference;
791    typedef typename iterator_traits<_Iter>::pointer         pointer;
792    typedef _If<__is_cpp17_random_access_iterator<_Iter>::value,
793        random_access_iterator_tag,
794        typename iterator_traits<_Iter>::iterator_category>  iterator_category;
795#if _LIBCPP_STD_VER > 17
796    typedef _If<__is_cpp17_random_access_iterator<_Iter>::value,
797        random_access_iterator_tag,
798        bidirectional_iterator_tag>                          iterator_concept;
799#endif
800
801    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
802    reverse_iterator() : __t(), current() {}
803    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
804    explicit reverse_iterator(_Iter __x) : __t(__x), current(__x) {}
805    template <class _Up>
806        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
807        reverse_iterator(const reverse_iterator<_Up>& __u) : __t(__u.base()), current(__u.base()) {}
808    template <class _Up>
809        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
810        reverse_iterator& operator=(const reverse_iterator<_Up>& __u)
811            { __t = current = __u.base(); return *this; }
812    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
813    _Iter base() const {return current;}
814    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
815    reference operator*() const {_Iter __tmp = current; return *--__tmp;}
816    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
817    pointer  operator->() const {return _VSTD::addressof(operator*());}
818    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
819    reverse_iterator& operator++() {--current; return *this;}
820    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
821    reverse_iterator  operator++(int) {reverse_iterator __tmp(*this); --current; return __tmp;}
822    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
823    reverse_iterator& operator--() {++current; return *this;}
824    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
825    reverse_iterator  operator--(int) {reverse_iterator __tmp(*this); ++current; return __tmp;}
826    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
827    reverse_iterator  operator+ (difference_type __n) const {return reverse_iterator(current - __n);}
828    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
829    reverse_iterator& operator+=(difference_type __n) {current -= __n; return *this;}
830    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
831    reverse_iterator  operator- (difference_type __n) const {return reverse_iterator(current + __n);}
832    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
833    reverse_iterator& operator-=(difference_type __n) {current += __n; return *this;}
834    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
835    reference         operator[](difference_type __n) const {return *(*this + __n);}
836};
837
838template <class _Iter1, class _Iter2>
839inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
840bool
841operator==(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
842{
843    return __x.base() == __y.base();
844}
845
846template <class _Iter1, class _Iter2>
847inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
848bool
849operator<(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
850{
851    return __x.base() > __y.base();
852}
853
854template <class _Iter1, class _Iter2>
855inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
856bool
857operator!=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
858{
859    return __x.base() != __y.base();
860}
861
862template <class _Iter1, class _Iter2>
863inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
864bool
865operator>(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
866{
867    return __x.base() < __y.base();
868}
869
870template <class _Iter1, class _Iter2>
871inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
872bool
873operator>=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
874{
875    return __x.base() <= __y.base();
876}
877
878template <class _Iter1, class _Iter2>
879inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
880bool
881operator<=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
882{
883    return __x.base() >= __y.base();
884}
885
886#ifndef _LIBCPP_CXX03_LANG
887template <class _Iter1, class _Iter2>
888inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
889auto
890operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
891-> decltype(__y.base() - __x.base())
892{
893    return __y.base() - __x.base();
894}
895#else
896template <class _Iter1, class _Iter2>
897inline _LIBCPP_INLINE_VISIBILITY
898typename reverse_iterator<_Iter1>::difference_type
899operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
900{
901    return __y.base() - __x.base();
902}
903#endif
904
905template <class _Iter>
906inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
907reverse_iterator<_Iter>
908operator+(typename reverse_iterator<_Iter>::difference_type __n, const reverse_iterator<_Iter>& __x)
909{
910    return reverse_iterator<_Iter>(__x.base() - __n);
911}
912
913#if _LIBCPP_STD_VER > 11
914template <class _Iter>
915inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
916reverse_iterator<_Iter> make_reverse_iterator(_Iter __i)
917{
918    return reverse_iterator<_Iter>(__i);
919}
920#endif
921
922template <class _Container>
923class _LIBCPP_TEMPLATE_VIS back_insert_iterator
924    : public iterator<output_iterator_tag,
925                      void,
926                      void,
927                      void,
928                      void>
929{
930protected:
931    _Container* container;
932public:
933    typedef _Container container_type;
934
935    _LIBCPP_INLINE_VISIBILITY explicit back_insert_iterator(_Container& __x) : container(_VSTD::addressof(__x)) {}
936    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(const typename _Container::value_type& __value_)
937        {container->push_back(__value_); return *this;}
938#ifndef _LIBCPP_CXX03_LANG
939    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator=(typename _Container::value_type&& __value_)
940        {container->push_back(_VSTD::move(__value_)); return *this;}
941#endif  // _LIBCPP_CXX03_LANG
942    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator*()     {return *this;}
943    _LIBCPP_INLINE_VISIBILITY back_insert_iterator& operator++()    {return *this;}
944    _LIBCPP_INLINE_VISIBILITY back_insert_iterator  operator++(int) {return *this;}
945};
946
947template <class _Container>
948inline _LIBCPP_INLINE_VISIBILITY
949back_insert_iterator<_Container>
950back_inserter(_Container& __x)
951{
952    return back_insert_iterator<_Container>(__x);
953}
954
955template <class _Container>
956class _LIBCPP_TEMPLATE_VIS front_insert_iterator
957    : public iterator<output_iterator_tag,
958                      void,
959                      void,
960                      void,
961                      void>
962{
963protected:
964    _Container* container;
965public:
966    typedef _Container container_type;
967
968    _LIBCPP_INLINE_VISIBILITY explicit front_insert_iterator(_Container& __x) : container(_VSTD::addressof(__x)) {}
969    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(const typename _Container::value_type& __value_)
970        {container->push_front(__value_); return *this;}
971#ifndef _LIBCPP_CXX03_LANG
972    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator=(typename _Container::value_type&& __value_)
973        {container->push_front(_VSTD::move(__value_)); return *this;}
974#endif  // _LIBCPP_CXX03_LANG
975    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator*()     {return *this;}
976    _LIBCPP_INLINE_VISIBILITY front_insert_iterator& operator++()    {return *this;}
977    _LIBCPP_INLINE_VISIBILITY front_insert_iterator  operator++(int) {return *this;}
978};
979
980template <class _Container>
981inline _LIBCPP_INLINE_VISIBILITY
982front_insert_iterator<_Container>
983front_inserter(_Container& __x)
984{
985    return front_insert_iterator<_Container>(__x);
986}
987
988template <class _Container>
989class _LIBCPP_TEMPLATE_VIS insert_iterator
990    : public iterator<output_iterator_tag,
991                      void,
992                      void,
993                      void,
994                      void>
995{
996protected:
997    _Container* container;
998    typename _Container::iterator iter;
999public:
1000    typedef _Container container_type;
1001
1002    _LIBCPP_INLINE_VISIBILITY insert_iterator(_Container& __x, typename _Container::iterator __i)
1003        : container(_VSTD::addressof(__x)), iter(__i) {}
1004    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(const typename _Container::value_type& __value_)
1005        {iter = container->insert(iter, __value_); ++iter; return *this;}
1006#ifndef _LIBCPP_CXX03_LANG
1007    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator=(typename _Container::value_type&& __value_)
1008        {iter = container->insert(iter, _VSTD::move(__value_)); ++iter; return *this;}
1009#endif  // _LIBCPP_CXX03_LANG
1010    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator*()        {return *this;}
1011    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++()       {return *this;}
1012    _LIBCPP_INLINE_VISIBILITY insert_iterator& operator++(int)    {return *this;}
1013};
1014
1015template <class _Container>
1016inline _LIBCPP_INLINE_VISIBILITY
1017insert_iterator<_Container>
1018inserter(_Container& __x, typename _Container::iterator __i)
1019{
1020    return insert_iterator<_Container>(__x, __i);
1021}
1022
1023template <class _Tp, class _CharT = char,
1024          class _Traits = char_traits<_CharT>, class _Distance = ptrdiff_t>
1025class _LIBCPP_TEMPLATE_VIS istream_iterator
1026    : public iterator<input_iterator_tag, _Tp, _Distance, const _Tp*, const _Tp&>
1027{
1028public:
1029    typedef _CharT char_type;
1030    typedef _Traits traits_type;
1031    typedef basic_istream<_CharT,_Traits> istream_type;
1032private:
1033    istream_type* __in_stream_;
1034    _Tp __value_;
1035public:
1036    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istream_iterator() : __in_stream_(nullptr), __value_() {}
1037    _LIBCPP_INLINE_VISIBILITY istream_iterator(istream_type& __s) : __in_stream_(_VSTD::addressof(__s))
1038        {
1039            if (!(*__in_stream_ >> __value_))
1040                __in_stream_ = nullptr;
1041        }
1042
1043    _LIBCPP_INLINE_VISIBILITY const _Tp& operator*() const {return __value_;}
1044    _LIBCPP_INLINE_VISIBILITY const _Tp* operator->() const {return _VSTD::addressof((operator*()));}
1045    _LIBCPP_INLINE_VISIBILITY istream_iterator& operator++()
1046        {
1047            if (!(*__in_stream_ >> __value_))
1048                __in_stream_ = nullptr;
1049            return *this;
1050        }
1051    _LIBCPP_INLINE_VISIBILITY istream_iterator  operator++(int)
1052        {istream_iterator __t(*this); ++(*this); return __t;}
1053
1054    template <class _Up, class _CharU, class _TraitsU, class _DistanceU>
1055    friend _LIBCPP_INLINE_VISIBILITY
1056    bool
1057    operator==(const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __x,
1058               const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __y);
1059
1060    template <class _Up, class _CharU, class _TraitsU, class _DistanceU>
1061    friend _LIBCPP_INLINE_VISIBILITY
1062    bool
1063    operator==(const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __x,
1064               const istream_iterator<_Up, _CharU, _TraitsU, _DistanceU>& __y);
1065};
1066
1067template <class _Tp, class _CharT, class _Traits, class _Distance>
1068inline _LIBCPP_INLINE_VISIBILITY
1069bool
1070operator==(const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __x,
1071           const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __y)
1072{
1073    return __x.__in_stream_ == __y.__in_stream_;
1074}
1075
1076template <class _Tp, class _CharT, class _Traits, class _Distance>
1077inline _LIBCPP_INLINE_VISIBILITY
1078bool
1079operator!=(const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __x,
1080           const istream_iterator<_Tp, _CharT, _Traits, _Distance>& __y)
1081{
1082    return !(__x == __y);
1083}
1084
1085template <class _Tp, class _CharT = char, class _Traits = char_traits<_CharT> >
1086class _LIBCPP_TEMPLATE_VIS ostream_iterator
1087    : public iterator<output_iterator_tag, void, void, void, void>
1088{
1089public:
1090    typedef output_iterator_tag             iterator_category;
1091    typedef void                            value_type;
1092#if _LIBCPP_STD_VER > 17
1093    typedef std::ptrdiff_t                  difference_type;
1094#else
1095    typedef void                            difference_type;
1096#endif
1097    typedef void                            pointer;
1098    typedef void                            reference;
1099    typedef _CharT                          char_type;
1100    typedef _Traits                         traits_type;
1101    typedef basic_ostream<_CharT, _Traits>  ostream_type;
1102
1103private:
1104    ostream_type* __out_stream_;
1105    const char_type* __delim_;
1106public:
1107    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s) _NOEXCEPT
1108        : __out_stream_(_VSTD::addressof(__s)), __delim_(nullptr) {}
1109    _LIBCPP_INLINE_VISIBILITY ostream_iterator(ostream_type& __s, const _CharT* __delimiter) _NOEXCEPT
1110        : __out_stream_(_VSTD::addressof(__s)), __delim_(__delimiter) {}
1111    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator=(const _Tp& __value_)
1112        {
1113            *__out_stream_ << __value_;
1114            if (__delim_)
1115                *__out_stream_ << __delim_;
1116            return *this;
1117        }
1118
1119    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator*()     {return *this;}
1120    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++()    {return *this;}
1121    _LIBCPP_INLINE_VISIBILITY ostream_iterator& operator++(int) {return *this;}
1122};
1123
1124template<class _CharT, class _Traits>
1125class _LIBCPP_TEMPLATE_VIS istreambuf_iterator
1126    : public iterator<input_iterator_tag, _CharT,
1127                      typename _Traits::off_type, _CharT*,
1128                      _CharT>
1129{
1130public:
1131    typedef _CharT                          char_type;
1132    typedef _Traits                         traits_type;
1133    typedef typename _Traits::int_type      int_type;
1134    typedef basic_streambuf<_CharT,_Traits> streambuf_type;
1135    typedef basic_istream<_CharT,_Traits>   istream_type;
1136private:
1137    mutable streambuf_type* __sbuf_;
1138
1139    class __proxy
1140    {
1141        char_type __keep_;
1142        streambuf_type* __sbuf_;
1143        _LIBCPP_INLINE_VISIBILITY __proxy(char_type __c, streambuf_type* __s)
1144            : __keep_(__c), __sbuf_(__s) {}
1145        friend class istreambuf_iterator;
1146    public:
1147        _LIBCPP_INLINE_VISIBILITY char_type operator*() const {return __keep_;}
1148    };
1149
1150    _LIBCPP_INLINE_VISIBILITY
1151    bool __test_for_eof() const
1152    {
1153        if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sgetc(), traits_type::eof()))
1154            __sbuf_ = nullptr;
1155        return __sbuf_ == nullptr;
1156    }
1157public:
1158    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR istreambuf_iterator() _NOEXCEPT : __sbuf_(nullptr) {}
1159    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(istream_type& __s) _NOEXCEPT
1160        : __sbuf_(__s.rdbuf()) {}
1161    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(streambuf_type* __s) _NOEXCEPT
1162        : __sbuf_(__s) {}
1163    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator(const __proxy& __p) _NOEXCEPT
1164        : __sbuf_(__p.__sbuf_) {}
1165
1166    _LIBCPP_INLINE_VISIBILITY char_type  operator*() const
1167        {return static_cast<char_type>(__sbuf_->sgetc());}
1168    _LIBCPP_INLINE_VISIBILITY istreambuf_iterator& operator++()
1169        {
1170            __sbuf_->sbumpc();
1171            return *this;
1172        }
1173    _LIBCPP_INLINE_VISIBILITY __proxy              operator++(int)
1174        {
1175            return __proxy(__sbuf_->sbumpc(), __sbuf_);
1176        }
1177
1178    _LIBCPP_INLINE_VISIBILITY bool equal(const istreambuf_iterator& __b) const
1179        {return __test_for_eof() == __b.__test_for_eof();}
1180};
1181
1182template <class _CharT, class _Traits>
1183inline _LIBCPP_INLINE_VISIBILITY
1184bool operator==(const istreambuf_iterator<_CharT,_Traits>& __a,
1185                const istreambuf_iterator<_CharT,_Traits>& __b)
1186                {return __a.equal(__b);}
1187
1188template <class _CharT, class _Traits>
1189inline _LIBCPP_INLINE_VISIBILITY
1190bool operator!=(const istreambuf_iterator<_CharT,_Traits>& __a,
1191                const istreambuf_iterator<_CharT,_Traits>& __b)
1192                {return !__a.equal(__b);}
1193
1194template <class _CharT, class _Traits>
1195class _LIBCPP_TEMPLATE_VIS ostreambuf_iterator
1196    : public iterator<output_iterator_tag, void, void, void, void>
1197{
1198public:
1199    typedef output_iterator_tag                 iterator_category;
1200    typedef void                                value_type;
1201#if _LIBCPP_STD_VER > 17
1202    typedef std::ptrdiff_t                      difference_type;
1203#else
1204    typedef void                                difference_type;
1205#endif
1206    typedef void                                pointer;
1207    typedef void                                reference;
1208    typedef _CharT                              char_type;
1209    typedef _Traits                             traits_type;
1210    typedef basic_streambuf<_CharT, _Traits>    streambuf_type;
1211    typedef basic_ostream<_CharT, _Traits>      ostream_type;
1212
1213private:
1214    streambuf_type* __sbuf_;
1215public:
1216    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(ostream_type& __s) _NOEXCEPT
1217        : __sbuf_(__s.rdbuf()) {}
1218    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator(streambuf_type* __s) _NOEXCEPT
1219        : __sbuf_(__s) {}
1220    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator=(_CharT __c)
1221        {
1222            if (__sbuf_ && traits_type::eq_int_type(__sbuf_->sputc(__c), traits_type::eof()))
1223                __sbuf_ = nullptr;
1224            return *this;
1225        }
1226    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator*()     {return *this;}
1227    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++()    {return *this;}
1228    _LIBCPP_INLINE_VISIBILITY ostreambuf_iterator& operator++(int) {return *this;}
1229    _LIBCPP_INLINE_VISIBILITY bool failed() const _NOEXCEPT {return __sbuf_ == nullptr;}
1230
1231    template <class _Ch, class _Tr>
1232    friend
1233    _LIBCPP_HIDDEN
1234    ostreambuf_iterator<_Ch, _Tr>
1235    __pad_and_output(ostreambuf_iterator<_Ch, _Tr> __s,
1236                     const _Ch* __ob, const _Ch* __op, const _Ch* __oe,
1237                     ios_base& __iob, _Ch __fl);
1238};
1239
1240template <class _Iter>
1241class _LIBCPP_TEMPLATE_VIS move_iterator
1242{
1243private:
1244    _Iter __i;
1245public:
1246    typedef _Iter                                            iterator_type;
1247    typedef typename iterator_traits<iterator_type>::value_type value_type;
1248    typedef typename iterator_traits<iterator_type>::difference_type difference_type;
1249    typedef iterator_type pointer;
1250    typedef _If<__is_cpp17_random_access_iterator<_Iter>::value,
1251        random_access_iterator_tag,
1252        typename iterator_traits<_Iter>::iterator_category>  iterator_category;
1253#if _LIBCPP_STD_VER > 17
1254    typedef input_iterator_tag                               iterator_concept;
1255#endif
1256
1257#ifndef _LIBCPP_CXX03_LANG
1258    typedef typename iterator_traits<iterator_type>::reference __reference;
1259    typedef typename conditional<
1260            is_reference<__reference>::value,
1261            typename remove_reference<__reference>::type&&,
1262            __reference
1263        >::type reference;
1264#else
1265    typedef typename iterator_traits<iterator_type>::reference reference;
1266#endif
1267
1268    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1269    move_iterator() : __i() {}
1270    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1271    explicit move_iterator(_Iter __x) : __i(__x) {}
1272    template <class _Up>
1273      _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1274      move_iterator(const move_iterator<_Up>& __u) : __i(__u.base()) {}
1275    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 _Iter base() const {return __i;}
1276    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1277    reference operator*() const { return static_cast<reference>(*__i); }
1278    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1279    pointer  operator->() const { return __i;}
1280    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1281    move_iterator& operator++() {++__i; return *this;}
1282    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1283    move_iterator  operator++(int) {move_iterator __tmp(*this); ++__i; return __tmp;}
1284    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1285    move_iterator& operator--() {--__i; return *this;}
1286    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1287    move_iterator  operator--(int) {move_iterator __tmp(*this); --__i; return __tmp;}
1288    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1289    move_iterator  operator+ (difference_type __n) const {return move_iterator(__i + __n);}
1290    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1291    move_iterator& operator+=(difference_type __n) {__i += __n; return *this;}
1292    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1293    move_iterator  operator- (difference_type __n) const {return move_iterator(__i - __n);}
1294    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1295    move_iterator& operator-=(difference_type __n) {__i -= __n; return *this;}
1296    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1297    reference operator[](difference_type __n) const { return static_cast<reference>(__i[__n]); }
1298};
1299
1300template <class _Iter1, class _Iter2>
1301inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1302bool
1303operator==(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1304{
1305    return __x.base() == __y.base();
1306}
1307
1308template <class _Iter1, class _Iter2>
1309inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1310bool
1311operator<(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1312{
1313    return __x.base() < __y.base();
1314}
1315
1316template <class _Iter1, class _Iter2>
1317inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1318bool
1319operator!=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1320{
1321    return __x.base() != __y.base();
1322}
1323
1324template <class _Iter1, class _Iter2>
1325inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1326bool
1327operator>(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1328{
1329    return __x.base() > __y.base();
1330}
1331
1332template <class _Iter1, class _Iter2>
1333inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1334bool
1335operator>=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1336{
1337    return __x.base() >= __y.base();
1338}
1339
1340template <class _Iter1, class _Iter2>
1341inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1342bool
1343operator<=(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1344{
1345    return __x.base() <= __y.base();
1346}
1347
1348#ifndef _LIBCPP_CXX03_LANG
1349template <class _Iter1, class _Iter2>
1350inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1351auto
1352operator-(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1353-> decltype(__x.base() - __y.base())
1354{
1355    return __x.base() - __y.base();
1356}
1357#else
1358template <class _Iter1, class _Iter2>
1359inline _LIBCPP_INLINE_VISIBILITY
1360typename move_iterator<_Iter1>::difference_type
1361operator-(const move_iterator<_Iter1>& __x, const move_iterator<_Iter2>& __y)
1362{
1363    return __x.base() - __y.base();
1364}
1365#endif
1366
1367template <class _Iter>
1368inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1369move_iterator<_Iter>
1370operator+(typename move_iterator<_Iter>::difference_type __n, const move_iterator<_Iter>& __x)
1371{
1372    return move_iterator<_Iter>(__x.base() + __n);
1373}
1374
1375template <class _Iter>
1376inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1377move_iterator<_Iter>
1378make_move_iterator(_Iter __i)
1379{
1380    return move_iterator<_Iter>(__i);
1381}
1382
1383// __wrap_iter
1384
1385template <class _Iter> class __wrap_iter;
1386
1387template <class _Iter1, class _Iter2>
1388_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1389bool
1390operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1391
1392template <class _Iter1, class _Iter2>
1393_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1394bool
1395operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1396
1397template <class _Iter1, class _Iter2>
1398_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1399bool
1400operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1401
1402template <class _Iter1, class _Iter2>
1403_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1404bool
1405operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1406
1407template <class _Iter1, class _Iter2>
1408_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1409bool
1410operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1411
1412template <class _Iter1, class _Iter2>
1413_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1414bool
1415operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1416
1417#ifndef _LIBCPP_CXX03_LANG
1418template <class _Iter1, class _Iter2>
1419_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1420auto
1421operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1422-> decltype(__x.base() - __y.base());
1423#else
1424template <class _Iter1, class _Iter2>
1425_LIBCPP_INLINE_VISIBILITY
1426typename __wrap_iter<_Iter1>::difference_type
1427operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1428#endif
1429
1430template <class _Iter>
1431_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1432__wrap_iter<_Iter>
1433operator+(typename __wrap_iter<_Iter>::difference_type, __wrap_iter<_Iter>) _NOEXCEPT;
1434
1435template <class _Ip, class _Op> _Op _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 copy(_Ip, _Ip, _Op);
1436template <class _B1, class _B2> _B2 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 copy_backward(_B1, _B1, _B2);
1437template <class _Ip, class _Op> _Op _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 move(_Ip, _Ip, _Op);
1438template <class _B1, class _B2> _B2 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 move_backward(_B1, _B1, _B2);
1439
1440template <class _Iter>
1441class __wrap_iter
1442{
1443public:
1444    typedef _Iter                                                      iterator_type;
1445    typedef typename iterator_traits<iterator_type>::value_type        value_type;
1446    typedef typename iterator_traits<iterator_type>::difference_type   difference_type;
1447    typedef typename iterator_traits<iterator_type>::pointer           pointer;
1448    typedef typename iterator_traits<iterator_type>::reference         reference;
1449    typedef typename iterator_traits<iterator_type>::iterator_category iterator_category;
1450#if _LIBCPP_STD_VER > 17
1451    typedef _If<__is_cpp17_contiguous_iterator<_Iter>::value,
1452                contiguous_iterator_tag, iterator_category>            iterator_concept;
1453#endif
1454
1455private:
1456    iterator_type __i;
1457public:
1458    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter() _NOEXCEPT
1459#if _LIBCPP_STD_VER > 11
1460                : __i{}
1461#endif
1462    {
1463#if _LIBCPP_DEBUG_LEVEL == 2
1464        __get_db()->__insert_i(this);
1465#endif
1466    }
1467    template <class _Up> _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1468        __wrap_iter(const __wrap_iter<_Up>& __u,
1469            typename enable_if<is_convertible<_Up, iterator_type>::value>::type* = nullptr) _NOEXCEPT
1470            : __i(__u.base())
1471    {
1472#if _LIBCPP_DEBUG_LEVEL == 2
1473        __get_db()->__iterator_copy(this, &__u);
1474#endif
1475    }
1476#if _LIBCPP_DEBUG_LEVEL == 2
1477    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1478    __wrap_iter(const __wrap_iter& __x)
1479        : __i(__x.base())
1480    {
1481        __get_db()->__iterator_copy(this, &__x);
1482    }
1483    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1484    __wrap_iter& operator=(const __wrap_iter& __x)
1485    {
1486        if (this != &__x)
1487        {
1488            __get_db()->__iterator_copy(this, &__x);
1489            __i = __x.__i;
1490        }
1491        return *this;
1492    }
1493    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1494    ~__wrap_iter()
1495    {
1496        __get_db()->__erase_i(this);
1497    }
1498#endif
1499    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG reference operator*() const _NOEXCEPT
1500    {
1501#if _LIBCPP_DEBUG_LEVEL == 2
1502        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1503                       "Attempted to dereference a non-dereferenceable iterator");
1504#endif
1505        return *__i;
1506    }
1507    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG pointer  operator->() const _NOEXCEPT
1508    {
1509#if _LIBCPP_DEBUG_LEVEL == 2
1510        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1511                       "Attempted to dereference a non-dereferenceable iterator");
1512#endif
1513        return (pointer)_VSTD::addressof(*__i);
1514    }
1515    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator++() _NOEXCEPT
1516    {
1517#if _LIBCPP_DEBUG_LEVEL == 2
1518        _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
1519                       "Attempted to increment non-incrementable iterator");
1520#endif
1521        ++__i;
1522        return *this;
1523    }
1524    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator++(int) _NOEXCEPT
1525        {__wrap_iter __tmp(*this); ++(*this); return __tmp;}
1526
1527    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator--() _NOEXCEPT
1528    {
1529#if _LIBCPP_DEBUG_LEVEL == 2
1530        _LIBCPP_ASSERT(__get_const_db()->__decrementable(this),
1531                       "Attempted to decrement non-decrementable iterator");
1532#endif
1533        --__i;
1534        return *this;
1535    }
1536    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator--(int) _NOEXCEPT
1537        {__wrap_iter __tmp(*this); --(*this); return __tmp;}
1538    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator+ (difference_type __n) const _NOEXCEPT
1539        {__wrap_iter __w(*this); __w += __n; return __w;}
1540    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator+=(difference_type __n) _NOEXCEPT
1541    {
1542#if _LIBCPP_DEBUG_LEVEL == 2
1543        _LIBCPP_ASSERT(__get_const_db()->__addable(this, __n),
1544                   "Attempted to add/subtract iterator outside of valid range");
1545#endif
1546        __i += __n;
1547        return *this;
1548    }
1549    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter  operator- (difference_type __n) const _NOEXCEPT
1550        {return *this + (-__n);}
1551    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter& operator-=(difference_type __n) _NOEXCEPT
1552        {*this += -__n; return *this;}
1553    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG reference    operator[](difference_type __n) const _NOEXCEPT
1554    {
1555#if _LIBCPP_DEBUG_LEVEL == 2
1556        _LIBCPP_ASSERT(__get_const_db()->__subscriptable(this, __n),
1557                   "Attempted to subscript iterator outside of valid range");
1558#endif
1559        return __i[__n];
1560    }
1561
1562    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG iterator_type base() const _NOEXCEPT {return __i;}
1563
1564private:
1565#if _LIBCPP_DEBUG_LEVEL == 2
1566    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter(const void* __p, iterator_type __x) : __i(__x)
1567    {
1568        __get_db()->__insert_ic(this, __p);
1569    }
1570#else
1571    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG __wrap_iter(iterator_type __x) _NOEXCEPT : __i(__x) {}
1572#endif
1573
1574    template <class _Up> friend class __wrap_iter;
1575    template <class _CharT, class _Traits, class _Alloc> friend class basic_string;
1576    template <class _Tp, class _Alloc> friend class _LIBCPP_TEMPLATE_VIS vector;
1577    template <class _Tp, size_t> friend class _LIBCPP_TEMPLATE_VIS span;
1578
1579    template <class _Iter1, class _Iter2>
1580    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1581    bool
1582    operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1583
1584    template <class _Iter1, class _Iter2>
1585    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1586    bool
1587    operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1588
1589    template <class _Iter1, class _Iter2>
1590    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1591    bool
1592    operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1593
1594    template <class _Iter1, class _Iter2>
1595    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1596    bool
1597    operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1598
1599    template <class _Iter1, class _Iter2>
1600    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1601    bool
1602    operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1603
1604    template <class _Iter1, class _Iter2>
1605    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1606    bool
1607    operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1608
1609#ifndef _LIBCPP_CXX03_LANG
1610    template <class _Iter1, class _Iter2>
1611    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1612    auto
1613    operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1614    -> decltype(__x.base() - __y.base());
1615#else
1616    template <class _Iter1, class _Iter2>
1617    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1618    typename __wrap_iter<_Iter1>::difference_type
1619    operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT;
1620#endif
1621
1622    template <class _Iter1>
1623    _LIBCPP_CONSTEXPR_IF_NODEBUG friend
1624    __wrap_iter<_Iter1>
1625    operator+(typename __wrap_iter<_Iter1>::difference_type, __wrap_iter<_Iter1>) _NOEXCEPT;
1626
1627    template <class _Ip, class _Op> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _Op copy(_Ip, _Ip, _Op);
1628    template <class _B1, class _B2> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _B2 copy_backward(_B1, _B1, _B2);
1629    template <class _Ip, class _Op> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _Op move(_Ip, _Ip, _Op);
1630    template <class _B1, class _B2> friend _LIBCPP_CONSTEXPR_AFTER_CXX17 _B2 move_backward(_B1, _B1, _B2);
1631};
1632
1633#if _LIBCPP_STD_VER <= 17
1634template <class _It>
1635struct __is_cpp17_contiguous_iterator<__wrap_iter<_It> > : __is_cpp17_contiguous_iterator<_It> {};
1636#endif
1637
1638template <class _Iter>
1639_LIBCPP_CONSTEXPR
1640_EnableIf<__is_cpp17_contiguous_iterator<_Iter>::value, decltype(_VSTD::__to_address(declval<_Iter>()))>
1641__to_address(__wrap_iter<_Iter> __w) _NOEXCEPT {
1642    return _VSTD::__to_address(__w.base());
1643}
1644
1645template <class _Iter1, class _Iter2>
1646inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1647bool
1648operator==(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1649{
1650    return __x.base() == __y.base();
1651}
1652
1653template <class _Iter1, class _Iter2>
1654inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1655bool
1656operator<(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1657{
1658#if _LIBCPP_DEBUG_LEVEL == 2
1659    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1660                   "Attempted to compare incomparable iterators");
1661#endif
1662    return __x.base() < __y.base();
1663}
1664
1665template <class _Iter1, class _Iter2>
1666inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1667bool
1668operator!=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1669{
1670    return !(__x == __y);
1671}
1672
1673template <class _Iter1, class _Iter2>
1674inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1675bool
1676operator>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1677{
1678    return __y < __x;
1679}
1680
1681template <class _Iter1, class _Iter2>
1682inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1683bool
1684operator>=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1685{
1686    return !(__x < __y);
1687}
1688
1689template <class _Iter1, class _Iter2>
1690inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1691bool
1692operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1693{
1694    return !(__y < __x);
1695}
1696
1697template <class _Iter1>
1698inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1699bool
1700operator!=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1701{
1702    return !(__x == __y);
1703}
1704
1705template <class _Iter1>
1706inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1707bool
1708operator>(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1709{
1710    return __y < __x;
1711}
1712
1713template <class _Iter1>
1714inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1715bool
1716operator>=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1717{
1718    return !(__x < __y);
1719}
1720
1721template <class _Iter1>
1722inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1723bool
1724operator<=(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter1>& __y) _NOEXCEPT
1725{
1726    return !(__y < __x);
1727}
1728
1729#ifndef _LIBCPP_CXX03_LANG
1730template <class _Iter1, class _Iter2>
1731inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1732auto
1733operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1734-> decltype(__x.base() - __y.base())
1735{
1736#if _LIBCPP_DEBUG_LEVEL == 2
1737    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1738                   "Attempted to subtract incompatible iterators");
1739#endif
1740    return __x.base() - __y.base();
1741}
1742#else
1743template <class _Iter1, class _Iter2>
1744inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1745typename __wrap_iter<_Iter1>::difference_type
1746operator-(const __wrap_iter<_Iter1>& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
1747{
1748#if _LIBCPP_DEBUG_LEVEL == 2
1749    _LIBCPP_ASSERT(__get_const_db()->__less_than_comparable(&__x, &__y),
1750                   "Attempted to subtract incompatible iterators");
1751#endif
1752    return __x.base() - __y.base();
1753}
1754#endif
1755
1756template <class _Iter>
1757inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1758__wrap_iter<_Iter>
1759operator+(typename __wrap_iter<_Iter>::difference_type __n,
1760          __wrap_iter<_Iter> __x) _NOEXCEPT
1761{
1762    __x += __n;
1763    return __x;
1764}
1765
1766template <class _Iter>
1767struct __libcpp_is_trivial_iterator
1768    : public _LIBCPP_BOOL_CONSTANT(is_pointer<_Iter>::value) {};
1769
1770template <class _Iter>
1771struct __libcpp_is_trivial_iterator<move_iterator<_Iter> >
1772    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1773
1774template <class _Iter>
1775struct __libcpp_is_trivial_iterator<reverse_iterator<_Iter> >
1776    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1777
1778template <class _Iter>
1779struct __libcpp_is_trivial_iterator<__wrap_iter<_Iter> >
1780    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value) {};
1781
1782
1783template <class _Tp, size_t _Np>
1784_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1785_Tp*
1786begin(_Tp (&__array)[_Np])
1787{
1788    return __array;
1789}
1790
1791template <class _Tp, size_t _Np>
1792_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1793_Tp*
1794end(_Tp (&__array)[_Np])
1795{
1796    return __array + _Np;
1797}
1798
1799#if !defined(_LIBCPP_CXX03_LANG)
1800
1801template <class _Cp>
1802_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1803auto
1804begin(_Cp& __c) -> decltype(__c.begin())
1805{
1806    return __c.begin();
1807}
1808
1809template <class _Cp>
1810_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1811auto
1812begin(const _Cp& __c) -> decltype(__c.begin())
1813{
1814    return __c.begin();
1815}
1816
1817template <class _Cp>
1818_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1819auto
1820end(_Cp& __c) -> decltype(__c.end())
1821{
1822    return __c.end();
1823}
1824
1825template <class _Cp>
1826_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1827auto
1828end(const _Cp& __c) -> decltype(__c.end())
1829{
1830    return __c.end();
1831}
1832
1833#if _LIBCPP_STD_VER > 11
1834
1835template <class _Tp, size_t _Np>
1836_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1837reverse_iterator<_Tp*> rbegin(_Tp (&__array)[_Np])
1838{
1839    return reverse_iterator<_Tp*>(__array + _Np);
1840}
1841
1842template <class _Tp, size_t _Np>
1843_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1844reverse_iterator<_Tp*> rend(_Tp (&__array)[_Np])
1845{
1846    return reverse_iterator<_Tp*>(__array);
1847}
1848
1849template <class _Ep>
1850_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1851reverse_iterator<const _Ep*> rbegin(initializer_list<_Ep> __il)
1852{
1853    return reverse_iterator<const _Ep*>(__il.end());
1854}
1855
1856template <class _Ep>
1857_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1858reverse_iterator<const _Ep*> rend(initializer_list<_Ep> __il)
1859{
1860    return reverse_iterator<const _Ep*>(__il.begin());
1861}
1862
1863template <class _Cp>
1864_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1865auto cbegin(const _Cp& __c) -> decltype(_VSTD::begin(__c))
1866{
1867    return _VSTD::begin(__c);
1868}
1869
1870template <class _Cp>
1871_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
1872auto cend(const _Cp& __c) -> decltype(_VSTD::end(__c))
1873{
1874    return _VSTD::end(__c);
1875}
1876
1877template <class _Cp>
1878_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1879auto rbegin(_Cp& __c) -> decltype(__c.rbegin())
1880{
1881    return __c.rbegin();
1882}
1883
1884template <class _Cp>
1885_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1886auto rbegin(const _Cp& __c) -> decltype(__c.rbegin())
1887{
1888    return __c.rbegin();
1889}
1890
1891template <class _Cp>
1892_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1893auto rend(_Cp& __c) -> decltype(__c.rend())
1894{
1895    return __c.rend();
1896}
1897
1898template <class _Cp>
1899_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1900auto rend(const _Cp& __c) -> decltype(__c.rend())
1901{
1902    return __c.rend();
1903}
1904
1905template <class _Cp>
1906_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1907auto crbegin(const _Cp& __c) -> decltype(_VSTD::rbegin(__c))
1908{
1909    return _VSTD::rbegin(__c);
1910}
1911
1912template <class _Cp>
1913_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
1914auto crend(const _Cp& __c) -> decltype(_VSTD::rend(__c))
1915{
1916    return _VSTD::rend(__c);
1917}
1918
1919#endif
1920
1921
1922#else  // defined(_LIBCPP_CXX03_LANG)
1923
1924template <class _Cp>
1925_LIBCPP_INLINE_VISIBILITY
1926typename _Cp::iterator
1927begin(_Cp& __c)
1928{
1929    return __c.begin();
1930}
1931
1932template <class _Cp>
1933_LIBCPP_INLINE_VISIBILITY
1934typename _Cp::const_iterator
1935begin(const _Cp& __c)
1936{
1937    return __c.begin();
1938}
1939
1940template <class _Cp>
1941_LIBCPP_INLINE_VISIBILITY
1942typename _Cp::iterator
1943end(_Cp& __c)
1944{
1945    return __c.end();
1946}
1947
1948template <class _Cp>
1949_LIBCPP_INLINE_VISIBILITY
1950typename _Cp::const_iterator
1951end(const _Cp& __c)
1952{
1953    return __c.end();
1954}
1955
1956#endif  // !defined(_LIBCPP_CXX03_LANG)
1957
1958#if _LIBCPP_STD_VER > 14
1959
1960// #if _LIBCPP_STD_VER > 11
1961// template <>
1962// struct _LIBCPP_TEMPLATE_VIS plus<void>
1963// {
1964//     template <class _T1, class _T2>
1965//     _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1966//     auto operator()(_T1&& __t, _T2&& __u) const
1967//     _NOEXCEPT_(noexcept(_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u)))
1968//     -> decltype        (_VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u))
1969//         { return        _VSTD::forward<_T1>(__t) + _VSTD::forward<_T2>(__u); }
1970//     typedef void is_transparent;
1971// };
1972// #endif
1973
1974template <class _Cont>
1975_LIBCPP_INLINE_VISIBILITY
1976constexpr auto size(const _Cont& __c)
1977_NOEXCEPT_(noexcept(__c.size()))
1978-> decltype        (__c.size())
1979{ return            __c.size(); }
1980
1981template <class _Tp, size_t _Sz>
1982_LIBCPP_INLINE_VISIBILITY
1983constexpr size_t size(const _Tp (&)[_Sz]) noexcept { return _Sz; }
1984
1985#if _LIBCPP_STD_VER > 17
1986template <class _Cont>
1987_LIBCPP_INLINE_VISIBILITY
1988constexpr auto ssize(const _Cont& __c)
1989_NOEXCEPT_(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size())))
1990->                              common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>
1991{ return            static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size()); }
1992
1993template <class _Tp, ptrdiff_t _Sz>
1994_LIBCPP_INLINE_VISIBILITY
1995constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept { return _Sz; }
1996#endif
1997
1998template <class _Cont>
1999_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
2000constexpr auto empty(const _Cont& __c)
2001_NOEXCEPT_(noexcept(__c.empty()))
2002-> decltype        (__c.empty())
2003{ return            __c.empty(); }
2004
2005template <class _Tp, size_t _Sz>
2006_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
2007constexpr bool empty(const _Tp (&)[_Sz]) noexcept { return false; }
2008
2009template <class _Ep>
2010_LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
2011constexpr bool empty(initializer_list<_Ep> __il) noexcept { return __il.size() == 0; }
2012
2013template <class _Cont> constexpr
2014_LIBCPP_INLINE_VISIBILITY
2015auto data(_Cont& __c)
2016_NOEXCEPT_(noexcept(__c.data()))
2017-> decltype        (__c.data())
2018{ return            __c.data(); }
2019
2020template <class _Cont> constexpr
2021_LIBCPP_INLINE_VISIBILITY
2022auto data(const _Cont& __c)
2023_NOEXCEPT_(noexcept(__c.data()))
2024-> decltype        (__c.data())
2025{ return            __c.data(); }
2026
2027template <class _Tp, size_t _Sz>
2028_LIBCPP_INLINE_VISIBILITY
2029constexpr _Tp* data(_Tp (&__array)[_Sz]) noexcept { return __array; }
2030
2031template <class _Ep>
2032_LIBCPP_INLINE_VISIBILITY
2033constexpr const _Ep* data(initializer_list<_Ep> __il) noexcept { return __il.begin(); }
2034#endif
2035
2036
2037_LIBCPP_END_NAMESPACE_STD
2038
2039#endif  // _LIBCPP_ITERATOR
2040