llvm-project

1
// -*- C++ -*-
2
//===----------------------------------------------------------------------===//
3
//
4
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5
// See https://llvm.org/LICENSE.txt for license information.
6
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7
//
8
//===----------------------------------------------------------------------===//
9

10
#ifndef _LIBCPP_ITERATOR
11
#define _LIBCPP_ITERATOR
12

13
/*
14
    iterator synopsis
15

16
#include <concepts>
17

18
namespace std
19
{
20
template<class> struct incrementable_traits;       // since C++20
21
template<class T>
22
  using iter_difference_t = see below;             // since C++20
23

24
template<class> struct indirectly_readable_traits; // since C++20
25
template<class T>
26
  using iter_value_t = see below;                  // since C++20
27

28
template<class Iterator>
29
struct iterator_traits;
30

31
template<class T>
32
  requires is_object_v<T>                    // since C++20
33
struct iterator_traits<T*>;
34

35
template<dereferenceable T>
36
  using iter_reference_t = decltype(*declval<T&>());
37

38
namespace ranges::inline unspecified {
39
    inline constexpr unspecified iter_move = unspecified; // since C++20, nodiscard as an extension
40
}}
41

42
template<dereferenceable T>
43
  requires ...
44
using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<T&>())); // since C++20
45

46
// [iterator.concepts], iterator concepts
47
// [iterator.concept.readable], concept indirectly_readable
48
template<class In>
49
  concept indirectly_readable = see below;                      // since C++20
50

51
template<indirectly_readable T>
52
  using iter_common_reference_t =
53
    common_reference_t<iter_reference_t<T>, iter_value_t<T>&>;  // since C++20
54

55
// [iterator.concept.writable], concept indirectly_writable
56
template<class Out, class T>
57
  concept indirectly_writable = see below;                // since C++20
58

59
// [iterator.concept.winc], concept weakly_incrementable
60
template<class I>
61
  concept weakly_incrementable = see below;                // since C++20
62

63
// [iterator.concept.inc], concept incrementable
64
template<class I>
65
  concept incrementable = see below;                       // since C++20
66

67
// [iterator.concept.iterator], concept input_or_output_iterator
68
  template<class I>
69
    concept input_or_output_iterator = see below;          // since C++20
70

71
// [iterator.concept.sentinel], concept sentinel_for
72
template<class S, class I>
73
  concept sentinel_for = see below;                        // since C++20
74

75
// [iterator.concept.sizedsentinel], concept sized_sentinel_for
76
template<class S, class I>
77
  inline constexpr bool disable_sized_sentinel_for = false;
78

79
template<class S, class I>
80
  concept sized_sentinel_for = see below;
81

82
// [iterator.concept.input], concept input_iterator
83
template<class I>
84
  concept input_iterator = see below;                      // since C++20
85

86
// [iterator.concept.output], concept output_iterator
87
template<class I, class T>
88
  concept output_iterator = see below;                     // since C++20
89

90
// [iterator.concept.forward], concept forward_iterator
91
template<class I>
92
  concept forward_iterator = see below;                    // since C++20
93

94
// [iterator.concept.bidir], concept bidirectional_iterator
95
template<class I>
96
  concept bidirectional_iterator = see below;              // since C++20
97

98
// [iterator.concept.random.access], concept random_access_iterator
99
template<class I>
100
  concept random_access_iterator = see below;              // since C++20
101

102
// [indirectcallable]
103
// [indirectcallable.indirectinvocable]
104
template<class F, class I>
105
  concept indirectly_unary_invocable = see below;          // since C++20
106

107
template<class F, class I>
108
  concept indirectly_regular_unary_invocable = see below;  // since C++20
109

110
template<class F, class I>
111
  concept indirect_unary_predicate = see below;            // since C++20
112

113
template<class F, class I1, class I2>
114
  concept indirect_binary_predicate = see below;           // since C++20
115

116
template<class F, class I1, class I2 = I1>
117
  concept indirect_equivalence_relation = see below;       // since C++20
118

119
template<class F, class I1, class I2 = I1>
120
  concept indirect_strict_weak_order = see below;          // since C++20
121

122
template<class F, class... Is>
123
  using indirect_result_t = see below;                     // since C++20
124

125
// [projected], projected
126
template<indirectly_readable I, indirectly_regular_unary_invocable<I> Proj>
127
  struct projected;                                        // since C++20
128

129
template<weakly_incrementable I, indirectly_regular_unary_invocable<I> Proj>
130
  struct incrementable_traits<projected<I, Proj>>;         // since C++20
131

132
// [alg.req.ind.move], concept indirectly_movable
133
template<class In, class Out>
134
  concept indirectly_movable = see below;                  // since C++20
135

136
template<class In, class Out>
137
  concept indirectly_movable_storable = see below;         // since C++20
138

139
// [alg.req.ind.copy], concept indirectly_copyable
140
template<class In, class Out>
141
  concept indirectly_copyable = see below;                 // since C++20
142

143
template<class In, class Out>
144
  concept indirectly_copyable_storable = see below;        // since C++20
145

146
// [alg.req.ind.swap], concept indirectly_swappable
147
template<class I1, class I2 = I1>
148
  concept indirectly_swappable = see below;                // since C++20
149

150
template<class I1, class I2, class R, class P1 = identity,
151
         class P2 = identity>
152
  concept indirectly_comparable =
153
    indirect_binary_predicate<R, projected<I1, P1>, projected<I2, P2>>; // since C++20
154

155
// [alg.req.permutable], concept permutable
156
template<class I>
157
  concept permutable = see below;                          // since C++20
158

159
 // [alg.req.mergeable], concept mergeable
160
template<class I1, class I2, class Out,
161
    class R = ranges::less, class P1 = identity, class P2 = identity>
162
  concept mergeable = see below;                           // since C++20
163

164
// [alg.req.sortable], concept sortable
165
template<class I, class R = ranges::less, class P = identity>
166
  concept sortable = see below;                            // since C++20
167

168
template<input_or_output_iterator I, sentinel_for<I> S>
169
  requires (!same_as<I, S> && copyable<I>)
170
class common_iterator;                                     // since C++20
171

172
template<class Category, class T, class Distance = ptrdiff_t,
173
         class Pointer = T*, class Reference = T&>
174
struct iterator                                            // deprecated in C++17
175
{
176
    typedef T         value_type;
177
    typedef Distance  difference_type;
178
    typedef Pointer   pointer;
179
    typedef Reference reference;
180
    typedef Category  iterator_category;
181
};
182

183
struct input_iterator_tag  {};
184
struct output_iterator_tag {};
185
struct forward_iterator_tag       : public input_iterator_tag         {};
186
struct bidirectional_iterator_tag : public forward_iterator_tag       {};
187
struct random_access_iterator_tag : public bidirectional_iterator_tag {};
188
struct contiguous_iterator_tag    : public random_access_iterator_tag {};
189

190
// 27.4.3, iterator operations
191
template <class InputIterator, class Distance>  // constexpr in C++17
192
  constexpr void advance(InputIterator& i, Distance n);
193

194
template <class InputIterator>  // constexpr in C++17
195
  constexpr typename iterator_traits<InputIterator>::difference_type
196
    distance(InputIterator first, InputIterator last);
197

198
template <class InputIterator>  // constexpr in C++17
199
  constexpr InputIterator next(InputIterator x,
200
typename iterator_traits<InputIterator>::difference_type n = 1);
201

202
template <class BidirectionalIterator>  // constexpr in C++17
203
  constexpr BidirectionalIterator prev(BidirectionalIterator x,
204
    typename iterator_traits<BidirectionalIterator>::difference_type n = 1);
205

206
// [range.iter.ops], range iterator operations
207
namespace ranges {
208
  // [range.iter.op.advance], ranges::advance
209
  template<input_or_output_iterator I>
210
    constexpr void advance(I& i, iter_difference_t<I> n);                          // since C++20
211
  template<input_or_output_iterator I, sentinel_for<I> S>
212
    constexpr void advance(I& i, S bound);                                         // since C++20
213
  template<input_or_output_iterator I, sentinel_for<I> S>
214
    constexpr iter_difference_t<I> advance(I& i, iter_difference_t<I> n, S bound); // since C++20
215
}
216

217
template <class Iterator>
218
class reverse_iterator
219
    : public iterator<typename iterator_traits<Iterator>::iterator_category, // until C++17
220
                      typename iterator_traits<Iterator>::value_type,
221
                      typename iterator_traits<Iterator>::difference_type,
222
                      typename iterator_traits<Iterator>::pointer,
223
                      typename iterator_traits<Iterator>::reference>
224
{
225
protected:
226
    Iterator current;
227
public:
228
    using iterator_type     = Iterator;
229
    using iterator_concept  = see below; // since C++20
230
    using iterator_category = typename iterator_traits<Iterator>::iterator_category; // since C++17, until C++20
231
    using iterator_category = see below; // since C++20
232
    using value_type        = typename iterator_traits<Iterator>::value_type; // since C++17, until C++20
233
    using value_type        = iter_value_t<Iterator>; // since C++20
234
    using difference_type   = typename iterator_traits<Iterator>::difference_type; // until C++20
235
    using difference_type   = iter_difference_t<Iterator>; // since C++20
236
    using pointer           = typename iterator_traits<Iterator>::pointer;
237
    using reference         = typename iterator_traits<Iterator>::reference; // until C++20
238
    using reference         = iter_reference_t<Iterator>; // since C++20
239

240
    constexpr reverse_iterator();
241
    constexpr explicit reverse_iterator(Iterator x);
242
    template <class U> constexpr reverse_iterator(const reverse_iterator<U>& u);
243
    template <class U> constexpr reverse_iterator& operator=(const reverse_iterator<U>& u);
244
    constexpr Iterator base() const;
245
    constexpr reference operator*() const;
246
    constexpr pointer   operator->() const; // until C++20
247
    constexpr pointer   operator->() const requires see below; // since C++20
248
    constexpr reverse_iterator& operator++();
249
    constexpr reverse_iterator  operator++(int);
250
    constexpr reverse_iterator& operator--();
251
    constexpr reverse_iterator  operator--(int);
252
    constexpr reverse_iterator  operator+ (difference_type n) const;
253
    constexpr reverse_iterator& operator+=(difference_type n);
254
    constexpr reverse_iterator  operator- (difference_type n) const;
255
    constexpr reverse_iterator& operator-=(difference_type n);
256
    constexpr unspecified       operator[](difference_type n) const;
257

258
    friend constexpr iter_rvalue_reference_t<Iterator>
259
      iter_move(const reverse_iterator& i) noexcept(see below);
260
    template<indirectly_swappable<Iterator> Iterator2>
261
      friend constexpr void
262
        iter_swap(const reverse_iterator& x,
263
                  const reverse_iterator<Iterator2>& y) noexcept(see below);
264
};
265

266
template <class Iterator1, class Iterator2>
267
constexpr bool                          // constexpr in C++17
268
operator==(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
269

270
template <class Iterator1, class Iterator2>
271
constexpr bool                          // constexpr in C++17
272
operator!=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
273

274
template <class Iterator1, class Iterator2>
275
constexpr bool                          // constexpr in C++17
276
operator<(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
277

278
template <class Iterator1, class Iterator2>
279
constexpr bool                          // constexpr in C++17
280
operator>(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
281

282
template <class Iterator1, class Iterator2>
283
constexpr bool                          // constexpr in C++17
284
operator<=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
285

286
template <class Iterator1, class Iterator2>
287
constexpr bool                          // constexpr in C++17
288
operator>=(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y);
289

290
template<class Iterator1, three_way_comparable_with<Iterator1> Iterator2>
291
  constexpr compare_three_way_result_t<Iterator1, Iterator2>
292
    operator<=>(const reverse_iterator<Iterator1>& x,
293
                const reverse_iterator<Iterator2>& y);
294

295
template <class Iterator1, class Iterator2>
296
constexpr auto
297
operator-(const reverse_iterator<Iterator1>& x, const reverse_iterator<Iterator2>& y)
298
-> decltype(__y.base() - __x.base());   // constexpr in C++17
299

300
template <class Iterator>
301
constexpr reverse_iterator<Iterator>
302
operator+(typename reverse_iterator<Iterator>::difference_type n,
303
          const reverse_iterator<Iterator>& x);   // constexpr in C++17
304

305
template <class Iterator>
306
constexpr reverse_iterator<Iterator> make_reverse_iterator(Iterator i); // C++14, constexpr in C++17
307

308
template<class Iterator1, class Iterator2>
309
    requires (!sized_sentinel_for<Iterator1, Iterator2>)
310
  inline constexpr bool disable_sized_sentinel_for<reverse_iterator<Iterator1>,
311
                                                   reverse_iterator<Iterator2>> = true;
312

313
template <class Container>
314
class back_insert_iterator
315
    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
316
{
317
protected:
318
    Container* container;
319
public:
320
    typedef Container                   container_type;
321
    typedef void                        value_type;
322
    typedef void                        difference_type; // until C++20
323
    typedef ptrdiff_t                   difference_type; // since C++20
324
    typedef void                        reference;
325
    typedef void                        pointer;
326

327
    explicit back_insert_iterator(Container& x);  // constexpr in C++20
328
    back_insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
329
    back_insert_iterator& operator*();  // constexpr in C++20
330
    back_insert_iterator& operator++();  // constexpr in C++20
331
    back_insert_iterator  operator++(int);  // constexpr in C++20
332
};
333

334
template <class Container> back_insert_iterator<Container> back_inserter(Container& x);  // constexpr in C++20
335

336
template <class Container>
337
class front_insert_iterator
338
    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
339
{
340
protected:
341
    Container* container;
342
public:
343
    typedef Container                    container_type;
344
    typedef void                         value_type;
345
    typedef void                         difference_type; // until C++20
346
    typedef ptrdiff_t                    difference_type; // since C++20
347
    typedef void                         reference;
348
    typedef void                         pointer;
349

350
    explicit front_insert_iterator(Container& x);  // constexpr in C++20
351
    front_insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
352
    front_insert_iterator& operator*();  // constexpr in C++20
353
    front_insert_iterator& operator++();  // constexpr in C++20
354
    front_insert_iterator  operator++(int);  // constexpr in C++20
355
};
356

357
template <class Container> front_insert_iterator<Container> front_inserter(Container& x);  // constexpr in C++20
358

359
template <class Container>
360
class insert_iterator
361
    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
362
{
363
protected:
364
    Container* container;
365
    typename Container::iterator iter;
366
public:
367
    typedef Container              container_type;
368
    typedef void                   value_type;
369
    typedef void                   difference_type; // until C++20
370
    typedef ptrdiff_t              difference_type; // since C++20
371
    typedef void                   reference;
372
    typedef void                   pointer;
373

374
    insert_iterator(Container& x, typename Container::iterator i);  // constexpr in C++20
375
    insert_iterator& operator=(const typename Container::value_type& value);  // constexpr in C++20
376
    insert_iterator& operator*();  // constexpr in C++20
377
    insert_iterator& operator++();  // constexpr in C++20
378
    insert_iterator& operator++(int);  // constexpr in C++20
379
};
380

381
template <class Container>
382
insert_iterator<Container> inserter(Container& x, typename Container::iterator i);  // until C++20
383
template <class Container>
384
constexpr insert_iterator<Container> inserter(Container& x, ranges::iterator_t<Container> i);  // since C++20
385

386
template <class Iterator>
387
class move_iterator {
388
public:
389
    using iterator_type     = Iterator;
390
    using iterator_concept  = see below; // From C++20
391
    using iterator_category = see below; // not always present starting from C++20
392
    using value_type        = iter_value_t<Iterator>; // Until C++20, iterator_traits<Iterator>::value_type
393
    using difference_type   = iter_difference_t<Iterator>; // Until C++20, iterator_traits<Iterator>::difference_type;
394
    using pointer           = Iterator;
395
    using reference         = iter_rvalue_reference_t<Iterator>; // Until C++20, value_type&&
396

397
    constexpr move_iterator();  // all the constexprs are in C++17
398
    constexpr explicit move_iterator(Iterator i);
399
    template <class U>
400
      constexpr move_iterator(const move_iterator<U>& u);
401
    template <class U>
402
      constexpr move_iterator& operator=(const move_iterator<U>& u);
403

404
    constexpr iterator_type base() const; // Until C++20
405
    constexpr const Iterator& base() const & noexcept; // From C++20
406
    constexpr Iterator base() &&; // From C++20
407

408
    constexpr reference operator*() const;
409
    constexpr pointer operator->() const; // Deprecated in C++20
410
    constexpr move_iterator& operator++();
411
    constexpr auto operator++(int); // Return type was move_iterator until C++20
412
    constexpr move_iterator& operator--();
413
    constexpr move_iterator operator--(int);
414
    constexpr move_iterator operator+(difference_type n) const;
415
    constexpr move_iterator& operator+=(difference_type n);
416
    constexpr move_iterator operator-(difference_type n) const;
417
    constexpr move_iterator& operator-=(difference_type n);
418
    constexpr reference operator[](difference_type n) const; // Return type unspecified until C++20
419

420
    template<sentinel_for<Iterator> S>
421
      friend constexpr bool
422
        operator==(const move_iterator& x, const move_sentinel<S>& y); // Since C++20
423
    template<sized_sentinel_for<Iterator> S>
424
      friend constexpr iter_difference_t<Iterator>
425
        operator-(const move_sentinel<S>& x, const move_iterator& y); // Since C++20
426
    template<sized_sentinel_for<Iterator> S>
427
      friend constexpr iter_difference_t<Iterator>
428
        operator-(const move_iterator& x, const move_sentinel<S>& y); // Since C++20
429
    friend constexpr iter_rvalue_reference_t<Iterator>
430
      iter_move(const move_iterator& i)
431
        noexcept(noexcept(ranges::iter_move(i.current))); // Since C++20
432
    template<indirectly_swappable<Iterator> Iterator2>
433
      friend constexpr void
434
        iter_swap(const move_iterator& x, const move_iterator<Iterator2>& y)
435
          noexcept(noexcept(ranges::iter_swap(x.current, y.current))); // Since C++20
436

437
private:
438
    Iterator current; // exposition only
439
};
440

441
template <class Iterator1, class Iterator2>
442
constexpr bool   // constexpr in C++17
443
operator==(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
444

445
template <class Iterator1, class Iterator2>
446
constexpr bool   // constexpr in C++17
447
operator!=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
448

449
template <class Iterator1, class Iterator2>
450
constexpr bool   // constexpr in C++17
451
operator<(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
452

453
template <class Iterator1, class Iterator2>
454
constexpr bool   // constexpr in C++17
455
operator<=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
456

457
template <class Iterator1, class Iterator2>
458
constexpr bool   // constexpr in C++17
459
operator>(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
460

461
template <class Iterator1, class Iterator2>
462
constexpr bool   // constexpr in C++17
463
operator>=(const move_iterator<Iterator1>& x, const move_iterator<Iterator2>& y);
464

465
template <class Iterator1, class Iterator2>
466
constexpr auto   // constexpr in C++17
467
operator-(const move_iterator<Iterator1>& x,
468
          const move_iterator<Iterator2>& y) -> decltype(x.base() - y.base());
469

470
template <class Iterator>
471
constexpr move_iterator<Iterator> operator+(   // constexpr in C++17
472
            typename move_iterator<Iterator>::difference_type n,
473
            const move_iterator<Iterator>& x);
474

475
template <class Iterator>   // constexpr in C++17
476
constexpr  move_iterator<Iterator> make_move_iterator(const Iterator& i);
477

478
template<class Iterator1, class Iterator2>
479
    requires (!sized_sentinel_for<Iterator1, Iterator2>)
480
  inline constexpr bool disable_sized_sentinel_for<move_iterator<Iterator1>,    // since C++20
481
                                                    move_iterator<Iterator2>> = true;
482

483
template<semiregular S>
484
class move_sentinel {
485
public:
486
  constexpr move_sentinel();
487
  constexpr explicit move_sentinel(S s);
488
  template<class S2>
489
    requires convertible_to<const S2&, S>
490
      constexpr move_sentinel(const move_sentinel<S2>& s);
491
  template<class S2>
492
    requires assignable_from<S&, const S2&>
493
      constexpr move_sentinel& operator=(const move_sentinel<S2>& s);
494

495
  constexpr S base() const;
496
private:
497
  S last;     // exposition only
498
};
499

500
// [default.sentinel], default sentinel
501
struct default_sentinel_t;
502
inline constexpr default_sentinel_t default_sentinel{};
503

504
// [iterators.counted], counted iterators
505
template<input_or_output_iterator I> class counted_iterator;
506

507
template<input_iterator I>
508
  requires see below
509
  struct iterator_traits<counted_iterator<I>>;
510

511
// [unreachable.sentinel], unreachable sentinel
512
struct unreachable_sentinel_t;
513
inline constexpr unreachable_sentinel_t unreachable_sentinel{};
514

515
template <class T, class charT = char, class traits = char_traits<charT>, class Distance = ptrdiff_t>
516
class istream_iterator
517
    : public iterator<input_iterator_tag, T, Distance, const T*, const T&> // until C++17
518
{
519
public:
520
    typedef input_iterator_tag           iterator_category;
521
    typedef T                            value_type;
522
    typedef Distance                     difference_type;
523
    typedef const T*                     pointer;
524
    typedef const T&                     reference;
525

526
    typedef charT                        char_type;
527
    typedef traits                       traits_type;
528
    typedef basic_istream<charT, traits> istream_type;
529

530
    istream_iterator(); // constexpr since C++11
531
    constexpr istream_iterator(default_sentinel_t); // since C++20
532
    istream_iterator(istream_type& s);
533
    istream_iterator(const istream_iterator& x);
534
    ~istream_iterator();
535

536
    const T& operator*() const;
537
    const T* operator->() const;
538
    istream_iterator& operator++();
539
    istream_iterator  operator++(int);
540
    friend bool operator==(const istream_iterator& i, default_sentinel_t); // since C++20
541
};
542

543
template <class T, class charT, class traits, class Distance>
544
bool operator==(const istream_iterator<T,charT,traits,Distance>& x,
545
                const istream_iterator<T,charT,traits,Distance>& y);
546
template <class T, class charT, class traits, class Distance>
547
bool operator!=(const istream_iterator<T,charT,traits,Distance>& x,
548
                const istream_iterator<T,charT,traits,Distance>& y); // until C++20
549

550
template <class T, class charT = char, class traits = char_traits<charT> >
551
class ostream_iterator
552
    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
553
{
554
public:
555
    typedef output_iterator_tag         iterator_category;
556
    typedef void                        value_type;
557
    typedef void                        difference_type; // until C++20
558
    typedef ptrdiff_t                   difference_type; // since C++20
559
    typedef void                        pointer;
560
    typedef void                        reference;
561

562
    typedef charT char_type;
563
    typedef traits traits_type;
564
    typedef basic_ostream<charT,traits> ostream_type;
565

566
    ostream_iterator(ostream_type& s);
567
    ostream_iterator(ostream_type& s, const charT* delimiter);
568
    ostream_iterator(const ostream_iterator& x);
569
    ~ostream_iterator();
570
    ostream_iterator& operator=(const T& value);
571

572
    ostream_iterator& operator*();
573
    ostream_iterator& operator++();
574
    ostream_iterator& operator++(int);
575
};
576

577
template<class charT, class traits = char_traits<charT> >
578
class istreambuf_iterator
579
    : public iterator<input_iterator_tag, charT, traits::off_type, unspecified, charT> // until C++17
580
{
581
public:
582
    typedef input_iterator_tag              iterator_category;
583
    typedef charT                           value_type;
584
    typedef traits::off_type                difference_type;
585
    typedef unspecified                     pointer;
586
    typedef charT                           reference;
587

588
    typedef charT                           char_type;
589
    typedef traits                          traits_type;
590
    typedef traits::int_type                int_type;
591
    typedef basic_streambuf<charT, traits>  streambuf_type;
592
    typedef basic_istream<charT, traits>    istream_type;
593

594
    istreambuf_iterator() noexcept; // constexpr since C++11
595
    constexpr istreambuf_iterator(default_sentinel_t) noexcept; // since C++20
596
    istreambuf_iterator(istream_type& s) noexcept;
597
    istreambuf_iterator(streambuf_type* s) noexcept;
598
    istreambuf_iterator(a-private-type) noexcept;
599

600
    charT                operator*() const;
601
    pointer operator->() const;
602
    istreambuf_iterator& operator++();
603
    a-private-type       operator++(int);
604

605
    bool equal(const istreambuf_iterator& b) const;
606
    friend bool operator==(const istreambuf_iterator& i, default_sentinel_t s); // since C++20
607
};
608

609
template <class charT, class traits>
610
bool operator==(const istreambuf_iterator<charT,traits>& a,
611
                const istreambuf_iterator<charT,traits>& b);
612
template <class charT, class traits>
613
bool operator!=(const istreambuf_iterator<charT,traits>& a,
614
                const istreambuf_iterator<charT,traits>& b); // until C++20
615

616
template <class charT, class traits = char_traits<charT> >
617
class ostreambuf_iterator
618
    : public iterator<output_iterator_tag, void, void, void, void> // until C++17
619
{
620
public:
621
    typedef output_iterator_tag            iterator_category;
622
    typedef void                           value_type;
623
    typedef void                           difference_type; // until C++20
624
    typedef ptrdiff_t                      difference_type; // since C++20
625
    typedef void                           pointer;
626
    typedef void                           reference;
627

628
    typedef charT                          char_type;
629
    typedef traits                         traits_type;
630
    typedef basic_streambuf<charT, traits> streambuf_type;
631
    typedef basic_ostream<charT, traits>   ostream_type;
632

633
    ostreambuf_iterator(ostream_type& s) noexcept;
634
    ostreambuf_iterator(streambuf_type* s) noexcept;
635
    ostreambuf_iterator& operator=(charT c);
636
    ostreambuf_iterator& operator*();
637
    ostreambuf_iterator& operator++();
638
    ostreambuf_iterator& operator++(int);
639
    bool failed() const noexcept;
640
};
641

642
template <class C> constexpr auto begin(C& c) -> decltype(c.begin());                   // constexpr since C++17
643
template <class C> constexpr auto begin(const C& c) -> decltype(c.begin());             // constexpr since C++17
644
template <class C> constexpr auto end(C& c) -> decltype(c.end());                       // constexpr since C++17
645
template <class C> constexpr auto end(const C& c) -> decltype(c.end());                 // constexpr since C++17
646
template <class T, size_t N> constexpr T* begin(T (&array)[N]) noexcept;
647
template <class T, size_t N> constexpr T* end(T (&array)[N]) noexcept;
648

649
template <class C> constexpr auto cbegin(const C& c) noexcept(see-below) -> decltype(std::begin(c)); // C++14
650
template <class C> constexpr auto cend(const C& c) noexcept(see-below) -> decltype(std::end(c));     // C++14
651
template <class C> constexpr auto rbegin(C& c) -> decltype(c.rbegin());                 // C++14, constexpr since C++17
652
template <class C> constexpr auto rbegin(const C& c) -> decltype(c.rbegin());           // C++14, constexpr since C++17
653
template <class C> constexpr auto rend(C& c) -> decltype(c.rend());                     // C++14, constexpr since C++17
654
template <class C> constexpr auto rend(const C& c) -> decltype(c.rend());               // C++14, constexpr since C++17
655
template <class E> constexpr reverse_iterator<const E*> rbegin(initializer_list<E> il); // C++14, constexpr since C++17
656
template <class E> constexpr reverse_iterator<const E*> rend(initializer_list<E> il);   // C++14, constexpr since C++17
657
template <class T, size_t N> constexpr reverse_iterator<T*> rbegin(T (&array)[N]);      // C++14, constexpr since C++17
658
template <class T, size_t N> constexpr reverse_iterator<T*> rend(T (&array)[N]);        // C++14, constexpr since C++17
659
template <class C> constexpr auto crbegin(const C& c) -> decltype(std::rbegin(c));      // C++14, constexpr since C++17
660
template <class C> constexpr auto crend(const C& c) -> decltype(std::rend(c));          // C++14, constexpr since C++17
661

662
// 24.8, container access:
663
template <class C> constexpr auto size(const C& c) -> decltype(c.size());         // C++17
664
template <class T, size_t N> constexpr size_t size(const T (&array)[N]) noexcept; // C++17
665

666
template <class C> constexpr auto ssize(const C& c)
667
    -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>;                    // C++20
668
template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
669

670
template <class C> constexpr auto empty(const C& c) -> decltype(c.empty());       // C++17
671
template <class T, size_t N> constexpr bool empty(const T (&array)[N]) noexcept;  // C++17
672
template <class E> constexpr bool empty(initializer_list<E> il) noexcept;         // C++17
673
template <class C> constexpr auto data(C& c) -> decltype(c.data());               // C++17
674
template <class C> constexpr auto data(const C& c) -> decltype(c.data());         // C++17
675
template <class T, size_t N> constexpr T* data(T (&array)[N]) noexcept;           // C++17
676
template <class E> constexpr const E* data(initializer_list<E> il) noexcept;      // C++17
677

678
}  // std
679

680
*/
681

682
#include <__config>
683
#include <__iterator/access.h>
684
#include <__iterator/advance.h>
685
#include <__iterator/back_insert_iterator.h>
686
#include <__iterator/bounded_iter.h>
687
#include <__iterator/common_iterator.h>
688
#include <__iterator/concepts.h>
689
#include <__iterator/counted_iterator.h>
690
#include <__iterator/data.h>
691
#include <__iterator/default_sentinel.h>
692
#include <__iterator/distance.h>
693
#include <__iterator/empty.h>
694
#include <__iterator/erase_if_container.h>
695
#include <__iterator/front_insert_iterator.h>
696
#include <__iterator/incrementable_traits.h>
697
#include <__iterator/indirectly_comparable.h>
698
#include <__iterator/insert_iterator.h>
699
#include <__iterator/istream_iterator.h>
700
#include <__iterator/istreambuf_iterator.h>
701
#include <__iterator/iter_move.h>
702
#include <__iterator/iter_swap.h>
703
#include <__iterator/iterator.h>
704
#include <__iterator/iterator_traits.h>
705
#include <__iterator/mergeable.h>
706
#include <__iterator/move_iterator.h>
707
#include <__iterator/move_sentinel.h>
708
#include <__iterator/next.h>
709
#include <__iterator/ostream_iterator.h>
710
#include <__iterator/ostreambuf_iterator.h>
711
#include <__iterator/permutable.h>
712
#include <__iterator/prev.h>
713
#include <__iterator/projected.h>
714
#include <__iterator/readable_traits.h>
715
#include <__iterator/reverse_access.h>
716
#include <__iterator/reverse_iterator.h>
717
#include <__iterator/size.h>
718
#include <__iterator/sortable.h>
719
#include <__iterator/unreachable_sentinel.h>
720
#include <__iterator/wrap_iter.h>
721
#include <__memory/addressof.h>
722
#include <__memory/pointer_traits.h>
723
#include <version>
724

725
// standard-mandated includes
726

727
// [iterator.synopsis]
728
#include <compare>
729
#include <concepts>
730

731
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
732
#  pragma GCC system_header
733
#endif
734

735
#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
736
#  include <cstdlib>
737
#  include <exception>
738
#  include <new>
739
#  include <type_traits>
740
#  include <typeinfo>
741
#  include <utility>
742
#endif
743

744
#endif // _LIBCPP_ITERATOR
745