1// -*- C++ -*-
2//===-------------------------- algorithm ---------------------------------===//
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_ALGORITHM
11#define _LIBCPP_ALGORITHM
12
13/*
14    algorithm synopsis
15
16#include <initializer_list>
17
18namespace std
19{
20
21template <class InputIterator, class Predicate>
22    constexpr bool     // constexpr in C++20
23    all_of(InputIterator first, InputIterator last, Predicate pred);
24
25template <class InputIterator, class Predicate>
26    constexpr bool     // constexpr in C++20
27    any_of(InputIterator first, InputIterator last, Predicate pred);
28
29template <class InputIterator, class Predicate>
30    constexpr bool     // constexpr in C++20
31    none_of(InputIterator first, InputIterator last, Predicate pred);
32
33template <class InputIterator, class Function>
34    constexpr Function          // constexpr in C++20
35    for_each(InputIterator first, InputIterator last, Function f);
36
37template<class InputIterator, class Size, class Function>
38    constexpr InputIterator     // constexpr in C++20
39    for_each_n(InputIterator first, Size n, Function f); // C++17
40
41template <class InputIterator, class T>
42    constexpr InputIterator     // constexpr in C++20
43    find(InputIterator first, InputIterator last, const T& value);
44
45template <class InputIterator, class Predicate>
46    constexpr InputIterator     // constexpr in C++20
47    find_if(InputIterator first, InputIterator last, Predicate pred);
48
49template<class InputIterator, class Predicate>
50    InputIterator               // constexpr in C++20
51    find_if_not(InputIterator first, InputIterator last, Predicate pred);
52
53template <class ForwardIterator1, class ForwardIterator2>
54    ForwardIterator1            // constexpr in C++20
55    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
56             ForwardIterator2 first2, ForwardIterator2 last2);
57
58template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
59    ForwardIterator1            // constexpr in C++20
60    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
61             ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
62
63template <class ForwardIterator1, class ForwardIterator2>
64    constexpr ForwardIterator1  // constexpr in C++20
65    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
66                  ForwardIterator2 first2, ForwardIterator2 last2);
67
68template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
69    constexpr ForwardIterator1  // constexpr in C++20
70    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
71                  ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
72
73template <class ForwardIterator>
74    constexpr ForwardIterator   // constexpr in C++20
75    adjacent_find(ForwardIterator first, ForwardIterator last);
76
77template <class ForwardIterator, class BinaryPredicate>
78    constexpr ForwardIterator   // constexpr in C++20
79    adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
80
81template <class InputIterator, class T>
82    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr in C++20
83    count(InputIterator first, InputIterator last, const T& value);
84
85template <class InputIterator, class Predicate>
86    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr in C++20
87    count_if(InputIterator first, InputIterator last, Predicate pred);
88
89template <class InputIterator1, class InputIterator2>
90    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
91    mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
92
93template <class InputIterator1, class InputIterator2>
94    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
95    mismatch(InputIterator1 first1, InputIterator1 last1,
96             InputIterator2 first2, InputIterator2 last2); // **C++14**
97
98template <class InputIterator1, class InputIterator2, class BinaryPredicate>
99    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
100    mismatch(InputIterator1 first1, InputIterator1 last1,
101             InputIterator2 first2, BinaryPredicate pred);
102
103template <class InputIterator1, class InputIterator2, class BinaryPredicate>
104    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
105    mismatch(InputIterator1 first1, InputIterator1 last1,
106             InputIterator2 first2, InputIterator2 last2,
107             BinaryPredicate pred); // **C++14**
108
109template <class InputIterator1, class InputIterator2>
110    constexpr bool      // constexpr in C++20
111    equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
112
113template <class InputIterator1, class InputIterator2>
114    constexpr bool      // constexpr in C++20
115    equal(InputIterator1 first1, InputIterator1 last1,
116          InputIterator2 first2, InputIterator2 last2); // **C++14**
117
118template <class InputIterator1, class InputIterator2, class BinaryPredicate>
119    constexpr bool      // constexpr in C++20
120    equal(InputIterator1 first1, InputIterator1 last1,
121          InputIterator2 first2, BinaryPredicate pred);
122
123template <class InputIterator1, class InputIterator2, class BinaryPredicate>
124    constexpr bool      // constexpr in C++20
125    equal(InputIterator1 first1, InputIterator1 last1,
126          InputIterator2 first2, InputIterator2 last2,
127          BinaryPredicate pred); // **C++14**
128
129template<class ForwardIterator1, class ForwardIterator2>
130    constexpr bool      // constexpr in C++20
131    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
132                   ForwardIterator2 first2);
133
134template<class ForwardIterator1, class ForwardIterator2>
135    constexpr bool      // constexpr in C++20
136    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
137                   ForwardIterator2 first2, ForwardIterator2 last2); // **C++14**
138
139template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
140    constexpr bool      // constexpr in C++20
141    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
142                   ForwardIterator2 first2, BinaryPredicate pred);
143
144template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
145    constexpr bool      // constexpr in C++20
146    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
147                   ForwardIterator2 first2, ForwardIterator2 last2,
148                   BinaryPredicate pred);  // **C++14**
149
150template <class ForwardIterator1, class ForwardIterator2>
151    constexpr ForwardIterator1      // constexpr in C++20
152    search(ForwardIterator1 first1, ForwardIterator1 last1,
153           ForwardIterator2 first2, ForwardIterator2 last2);
154
155template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
156    constexpr ForwardIterator1      // constexpr in C++20
157    search(ForwardIterator1 first1, ForwardIterator1 last1,
158           ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
159
160template <class ForwardIterator, class Size, class T>
161    constexpr ForwardIterator       // constexpr in C++20
162    search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value);
163
164template <class ForwardIterator, class Size, class T, class BinaryPredicate>
165    constexpr ForwardIterator       // constexpr in C++20
166    search_n(ForwardIterator first, ForwardIterator last,
167             Size count, const T& value, BinaryPredicate pred);
168
169template <class InputIterator, class OutputIterator>
170    OutputIterator
171    copy(InputIterator first, InputIterator last, OutputIterator result);
172
173template<class InputIterator, class OutputIterator, class Predicate>
174    OutputIterator
175    copy_if(InputIterator first, InputIterator last,
176            OutputIterator result, Predicate pred);
177
178template<class InputIterator, class Size, class OutputIterator>
179    OutputIterator
180    copy_n(InputIterator first, Size n, OutputIterator result);
181
182template <class BidirectionalIterator1, class BidirectionalIterator2>
183    BidirectionalIterator2
184    copy_backward(BidirectionalIterator1 first, BidirectionalIterator1 last,
185                  BidirectionalIterator2 result);
186
187template <class ForwardIterator1, class ForwardIterator2>
188    ForwardIterator2
189    swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2);
190
191template <class ForwardIterator1, class ForwardIterator2>
192    void
193    iter_swap(ForwardIterator1 a, ForwardIterator2 b);
194
195template <class InputIterator, class OutputIterator, class UnaryOperation>
196    constexpr OutputIterator      // constexpr in C++20
197    transform(InputIterator first, InputIterator last, OutputIterator result, UnaryOperation op);
198
199template <class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation>
200    constexpr OutputIterator      // constexpr in C++20
201    transform(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2,
202              OutputIterator result, BinaryOperation binary_op);
203
204template <class ForwardIterator, class T>
205    constexpr void      // constexpr in C++20
206    replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value);
207
208template <class ForwardIterator, class Predicate, class T>
209    constexpr void      // constexpr in C++20
210    replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const T& new_value);
211
212template <class InputIterator, class OutputIterator, class T>
213    constexpr OutputIterator      // constexpr in C++20
214    replace_copy(InputIterator first, InputIterator last, OutputIterator result,
215                 const T& old_value, const T& new_value);
216
217template <class InputIterator, class OutputIterator, class Predicate, class T>
218    constexpr OutputIterator      // constexpr in C++20
219    replace_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred, const T& new_value);
220
221template <class ForwardIterator, class T>
222    constexpr void      // constexpr in C++20
223    fill(ForwardIterator first, ForwardIterator last, const T& value);
224
225template <class OutputIterator, class Size, class T>
226    constexpr OutputIterator      // constexpr in C++20
227    fill_n(OutputIterator first, Size n, const T& value);
228
229template <class ForwardIterator, class Generator>
230    constexpr void      // constexpr in C++20
231    generate(ForwardIterator first, ForwardIterator last, Generator gen);
232
233template <class OutputIterator, class Size, class Generator>
234    constexpr OutputIterator      // constexpr in C++20
235    generate_n(OutputIterator first, Size n, Generator gen);
236
237template <class ForwardIterator, class T>
238    constexpr ForwardIterator     // constexpr in C++20
239    remove(ForwardIterator first, ForwardIterator last, const T& value);
240
241template <class ForwardIterator, class Predicate>
242    constexpr ForwardIterator     // constexpr in C++20
243    remove_if(ForwardIterator first, ForwardIterator last, Predicate pred);
244
245template <class InputIterator, class OutputIterator, class T>
246    constexpr OutputIterator     // constexpr in C++20
247    remove_copy(InputIterator first, InputIterator last, OutputIterator result, const T& value);
248
249template <class InputIterator, class OutputIterator, class Predicate>
250    constexpr OutputIterator     // constexpr in C++20
251    remove_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred);
252
253template <class ForwardIterator>
254    ForwardIterator
255    unique(ForwardIterator first, ForwardIterator last);
256
257template <class ForwardIterator, class BinaryPredicate>
258    ForwardIterator
259    unique(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
260
261template <class InputIterator, class OutputIterator>
262    OutputIterator
263    unique_copy(InputIterator first, InputIterator last, OutputIterator result);
264
265template <class InputIterator, class OutputIterator, class BinaryPredicate>
266    OutputIterator
267    unique_copy(InputIterator first, InputIterator last, OutputIterator result, BinaryPredicate pred);
268
269template <class BidirectionalIterator>
270    void
271    reverse(BidirectionalIterator first, BidirectionalIterator last);
272
273template <class BidirectionalIterator, class OutputIterator>
274    constexpr OutputIterator       // constexpr in C++20
275    reverse_copy(BidirectionalIterator first, BidirectionalIterator last, OutputIterator result);
276
277template <class ForwardIterator>
278    ForwardIterator
279    rotate(ForwardIterator first, ForwardIterator middle, ForwardIterator last);
280
281template <class ForwardIterator, class OutputIterator>
282    OutputIterator
283    rotate_copy(ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result);
284
285template <class RandomAccessIterator>
286    void
287    random_shuffle(RandomAccessIterator first, RandomAccessIterator last); // deprecated in C++14, removed in C++17
288
289template <class RandomAccessIterator, class RandomNumberGenerator>
290    void
291    random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
292                   RandomNumberGenerator& rand);  // deprecated in C++14, removed in C++17
293
294template<class PopulationIterator, class SampleIterator,
295         class Distance, class UniformRandomBitGenerator>
296    SampleIterator sample(PopulationIterator first, PopulationIterator last,
297                          SampleIterator out, Distance n,
298                          UniformRandomBitGenerator&& g); // C++17
299
300template<class RandomAccessIterator, class UniformRandomNumberGenerator>
301    void shuffle(RandomAccessIterator first, RandomAccessIterator last,
302                 UniformRandomNumberGenerator&& g);
303
304template <class InputIterator, class Predicate>
305    constexpr bool  // constexpr in C++20
306    is_partitioned(InputIterator first, InputIterator last, Predicate pred);
307
308template <class ForwardIterator, class Predicate>
309    ForwardIterator
310    partition(ForwardIterator first, ForwardIterator last, Predicate pred);
311
312template <class InputIterator, class OutputIterator1,
313          class OutputIterator2, class Predicate>
314    constexpr pair<OutputIterator1, OutputIterator2>   // constexpr in C++20
315    partition_copy(InputIterator first, InputIterator last,
316                   OutputIterator1 out_true, OutputIterator2 out_false,
317                   Predicate pred);
318
319template <class ForwardIterator, class Predicate>
320    ForwardIterator
321    stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);
322
323template<class ForwardIterator, class Predicate>
324    constexpr ForwardIterator  // constexpr in C++20
325    partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
326
327template <class ForwardIterator>
328    constexpr bool  // constexpr in C++20
329    is_sorted(ForwardIterator first, ForwardIterator last);
330
331template <class ForwardIterator, class Compare>
332    bool
333    is_sorted(ForwardIterator first, ForwardIterator last, Compare comp);
334
335template<class ForwardIterator>
336    constexpr ForwardIterator    // constexpr in C++20
337    is_sorted_until(ForwardIterator first, ForwardIterator last);
338
339template <class ForwardIterator, class Compare>
340    constexpr ForwardIterator    // constexpr in C++20
341    is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
342
343template <class RandomAccessIterator>
344    void
345    sort(RandomAccessIterator first, RandomAccessIterator last);
346
347template <class RandomAccessIterator, class Compare>
348    void
349    sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
350
351template <class RandomAccessIterator>
352    void
353    stable_sort(RandomAccessIterator first, RandomAccessIterator last);
354
355template <class RandomAccessIterator, class Compare>
356    void
357    stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
358
359template <class RandomAccessIterator>
360    void
361    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last);
362
363template <class RandomAccessIterator, class Compare>
364    void
365    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp);
366
367template <class InputIterator, class RandomAccessIterator>
368    RandomAccessIterator
369    partial_sort_copy(InputIterator first, InputIterator last,
370                      RandomAccessIterator result_first, RandomAccessIterator result_last);
371
372template <class InputIterator, class RandomAccessIterator, class Compare>
373    RandomAccessIterator
374    partial_sort_copy(InputIterator first, InputIterator last,
375                      RandomAccessIterator result_first, RandomAccessIterator result_last, Compare comp);
376
377template <class RandomAccessIterator>
378    void
379    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last);
380
381template <class RandomAccessIterator, class Compare>
382    void
383    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last, Compare comp);
384
385template <class ForwardIterator, class T>
386    constexpr ForwardIterator                         // constexpr in C++20
387    lower_bound(ForwardIterator first, ForwardIterator last, const T& value);
388
389template <class ForwardIterator, class T, class Compare>
390    constexpr ForwardIterator                         // constexpr in C++20
391    lower_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
392
393template <class ForwardIterator, class T>
394    constexpr ForwardIterator                         // constexpr in C++20
395    upper_bound(ForwardIterator first, ForwardIterator last, const T& value);
396
397template <class ForwardIterator, class T, class Compare>
398    constexpr ForwardIterator                         // constexpr in C++20
399    upper_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
400
401template <class ForwardIterator, class T>
402    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
403    equal_range(ForwardIterator first, ForwardIterator last, const T& value);
404
405template <class ForwardIterator, class T, class Compare>
406    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
407    equal_range(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
408
409template <class ForwardIterator, class T>
410    constexpr bool                                    // constexpr in C++20
411    binary_search(ForwardIterator first, ForwardIterator last, const T& value);
412
413template <class ForwardIterator, class T, class Compare>
414    constexpr bool                                    // constexpr in C++20
415    binary_search(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
416
417template <class InputIterator1, class InputIterator2, class OutputIterator>
418    OutputIterator
419    merge(InputIterator1 first1, InputIterator1 last1,
420          InputIterator2 first2, InputIterator2 last2, OutputIterator result);
421
422template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
423    OutputIterator
424    merge(InputIterator1 first1, InputIterator1 last1,
425          InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
426
427template <class BidirectionalIterator>
428    void
429    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last);
430
431template <class BidirectionalIterator, class Compare>
432    void
433    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp);
434
435template <class InputIterator1, class InputIterator2>
436    constexpr bool                                    // constexpr in C++20
437    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
438
439template <class InputIterator1, class InputIterator2, class Compare>
440    constexpr bool                                    // constexpr in C++20
441    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp);
442
443template <class InputIterator1, class InputIterator2, class OutputIterator>
444    OutputIterator
445    set_union(InputIterator1 first1, InputIterator1 last1,
446              InputIterator2 first2, InputIterator2 last2, OutputIterator result);
447
448template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
449    OutputIterator
450    set_union(InputIterator1 first1, InputIterator1 last1,
451              InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
452
453template <class InputIterator1, class InputIterator2, class OutputIterator>
454    constexpr OutputIterator                         // constexpr in C++20
455    set_intersection(InputIterator1 first1, InputIterator1 last1,
456                     InputIterator2 first2, InputIterator2 last2, OutputIterator result);
457
458template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
459    constexpr OutputIterator                         // constexpr in C++20
460    set_intersection(InputIterator1 first1, InputIterator1 last1,
461                     InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
462
463template <class InputIterator1, class InputIterator2, class OutputIterator>
464    OutputIterator
465    set_difference(InputIterator1 first1, InputIterator1 last1,
466                   InputIterator2 first2, InputIterator2 last2, OutputIterator result);
467
468template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
469    OutputIterator
470    set_difference(InputIterator1 first1, InputIterator1 last1,
471                   InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
472
473template <class InputIterator1, class InputIterator2, class OutputIterator>
474    OutputIterator
475    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
476                             InputIterator2 first2, InputIterator2 last2, OutputIterator result);
477
478template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
479    OutputIterator
480    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
481                             InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
482
483template <class RandomAccessIterator>
484    void
485    push_heap(RandomAccessIterator first, RandomAccessIterator last);
486
487template <class RandomAccessIterator, class Compare>
488    void
489    push_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
490
491template <class RandomAccessIterator>
492    void
493    pop_heap(RandomAccessIterator first, RandomAccessIterator last);
494
495template <class RandomAccessIterator, class Compare>
496    void
497    pop_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
498
499template <class RandomAccessIterator>
500    void
501    make_heap(RandomAccessIterator first, RandomAccessIterator last);
502
503template <class RandomAccessIterator, class Compare>
504    void
505    make_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
506
507template <class RandomAccessIterator>
508    void
509    sort_heap(RandomAccessIterator first, RandomAccessIterator last);
510
511template <class RandomAccessIterator, class Compare>
512    void
513    sort_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
514
515template <class RandomAccessIterator>
516    constexpr bool   // constexpr in C++20
517    is_heap(RandomAccessIterator first, RandomAccessiterator last);
518
519template <class RandomAccessIterator, class Compare>
520    constexpr bool   // constexpr in C++20
521    is_heap(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
522
523template <class RandomAccessIterator>
524    constexpr RandomAccessIterator   // constexpr in C++20
525    is_heap_until(RandomAccessIterator first, RandomAccessiterator last);
526
527template <class RandomAccessIterator, class Compare>
528    constexpr RandomAccessIterator   // constexpr in C++20
529    is_heap_until(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
530
531template <class ForwardIterator>
532    ForwardIterator
533    min_element(ForwardIterator first, ForwardIterator last);  // constexpr in C++14
534
535template <class ForwardIterator, class Compare>
536    ForwardIterator
537    min_element(ForwardIterator first, ForwardIterator last, Compare comp);  // constexpr in C++14
538
539template <class T>
540    const T&
541    min(const T& a, const T& b);  // constexpr in C++14
542
543template <class T, class Compare>
544    const T&
545    min(const T& a, const T& b, Compare comp);  // constexpr in C++14
546
547template<class T>
548    T
549    min(initializer_list<T> t);  // constexpr in C++14
550
551template<class T, class Compare>
552    T
553    min(initializer_list<T> t, Compare comp);  // constexpr in C++14
554
555template<class T>
556    constexpr const T& clamp( const T& v, const T& lo, const T& hi );               // C++17
557
558template<class T, class Compare>
559    constexpr const T& clamp( const T& v, const T& lo, const T& hi, Compare comp ); // C++17
560
561template <class ForwardIterator>
562    ForwardIterator
563    max_element(ForwardIterator first, ForwardIterator last);  // constexpr in C++14
564
565template <class ForwardIterator, class Compare>
566    ForwardIterator
567    max_element(ForwardIterator first, ForwardIterator last, Compare comp);  // constexpr in C++14
568
569template <class T>
570    const T&
571    max(const T& a, const T& b); // constexpr in C++14
572
573template <class T, class Compare>
574    const T&
575    max(const T& a, const T& b, Compare comp);  // constexpr in C++14
576
577template<class T>
578    T
579    max(initializer_list<T> t);  // constexpr in C++14
580
581template<class T, class Compare>
582    T
583    max(initializer_list<T> t, Compare comp);  // constexpr in C++14
584
585template<class ForwardIterator>
586    pair<ForwardIterator, ForwardIterator>
587    minmax_element(ForwardIterator first, ForwardIterator last);   // constexpr in C++14
588
589template<class ForwardIterator, class Compare>
590    pair<ForwardIterator, ForwardIterator>
591    minmax_element(ForwardIterator first, ForwardIterator last, Compare comp);   // constexpr in C++14
592
593template<class T>
594    pair<const T&, const T&>
595    minmax(const T& a, const T& b);  // constexpr in C++14
596
597template<class T, class Compare>
598    pair<const T&, const T&>
599    minmax(const T& a, const T& b, Compare comp);  // constexpr in C++14
600
601template<class T>
602    pair<T, T>
603    minmax(initializer_list<T> t);  // constexpr in C++14
604
605template<class T, class Compare>
606    pair<T, T>
607    minmax(initializer_list<T> t, Compare comp);  // constexpr in C++14
608
609template <class InputIterator1, class InputIterator2>
610    constexpr bool     // constexpr in C++20
611    lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
612
613template <class InputIterator1, class InputIterator2, class Compare>
614    constexpr bool     // constexpr in C++20
615    lexicographical_compare(InputIterator1 first1, InputIterator1 last1,
616                            InputIterator2 first2, InputIterator2 last2, Compare comp);
617
618template <class BidirectionalIterator>
619    bool
620    next_permutation(BidirectionalIterator first, BidirectionalIterator last);
621
622template <class BidirectionalIterator, class Compare>
623    bool
624    next_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
625
626template <class BidirectionalIterator>
627    bool
628    prev_permutation(BidirectionalIterator first, BidirectionalIterator last);
629
630template <class BidirectionalIterator, class Compare>
631    bool
632    prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
633
634}  // std
635
636*/
637
638#include <__config>
639#include <initializer_list>
640#include <type_traits>
641#include <cstring>
642#include <utility> // needed to provide swap_ranges.
643#include <memory>
644#include <functional>
645#include <iterator>
646#include <cstddef>
647#include <bit>
648#include <version>
649
650#include <__debug>
651
652#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
653#pragma GCC system_header
654#endif
655
656_LIBCPP_PUSH_MACROS
657#include <__undef_macros>
658
659
660_LIBCPP_BEGIN_NAMESPACE_STD
661
662// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
663//   * That only works with C++14 and later, and
664//   * We haven't included <functional> here.
665template <class _T1, class _T2 = _T1>
666struct __equal_to
667{
668    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
669    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T2& __y) const {return __x == __y;}
670    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T1& __y) const {return __x == __y;}
671    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T2& __y) const {return __x == __y;}
672};
673
674template <class _T1>
675struct __equal_to<_T1, _T1>
676{
677    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
678    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
679};
680
681template <class _T1>
682struct __equal_to<const _T1, _T1>
683{
684    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
685    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
686};
687
688template <class _T1>
689struct __equal_to<_T1, const _T1>
690{
691    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
692    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
693};
694
695template <class _T1, class _T2 = _T1>
696struct __less
697{
698    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
699    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
700
701    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
702    bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
703
704    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
705    bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
706
707    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
708    bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
709};
710
711template <class _T1>
712struct __less<_T1, _T1>
713{
714    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
715    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
716};
717
718template <class _T1>
719struct __less<const _T1, _T1>
720{
721    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
722    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
723};
724
725template <class _T1>
726struct __less<_T1, const _T1>
727{
728    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
729    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
730};
731
732template <class _Predicate>
733class __invert // invert the sense of a comparison
734{
735private:
736    _Predicate __p_;
737public:
738    _LIBCPP_INLINE_VISIBILITY __invert() {}
739
740    _LIBCPP_INLINE_VISIBILITY
741    explicit __invert(_Predicate __p) : __p_(__p) {}
742
743    template <class _T1>
744    _LIBCPP_INLINE_VISIBILITY
745    bool operator()(const _T1& __x) {return !__p_(__x);}
746
747    template <class _T1, class _T2>
748    _LIBCPP_INLINE_VISIBILITY
749    bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
750};
751
752// Perform division by two quickly for positive integers (llvm.org/PR39129)
753
754template <typename _Integral>
755_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
756typename enable_if
757<
758    is_integral<_Integral>::value,
759    _Integral
760>::type
761__half_positive(_Integral __value)
762{
763    return static_cast<_Integral>(static_cast<typename make_unsigned<_Integral>::type>(__value) / 2);
764}
765
766template <typename _Tp>
767_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
768typename enable_if
769<
770    !is_integral<_Tp>::value,
771    _Tp
772>::type
773__half_positive(_Tp __value)
774{
775    return __value / 2;
776}
777
778#ifdef _LIBCPP_DEBUG
779
780template <class _Compare>
781struct __debug_less
782{
783    _Compare &__comp_;
784    _LIBCPP_CONSTEXPR_AFTER_CXX17
785    __debug_less(_Compare& __c) : __comp_(__c) {}
786
787    template <class _Tp, class _Up>
788    _LIBCPP_CONSTEXPR_AFTER_CXX17
789    bool operator()(const _Tp& __x,  const _Up& __y)
790    {
791        bool __r = __comp_(__x, __y);
792        if (__r)
793            __do_compare_assert(0, __y, __x);
794        return __r;
795    }
796
797    template <class _Tp, class _Up>
798    _LIBCPP_CONSTEXPR_AFTER_CXX17
799    bool operator()(_Tp& __x,  _Up& __y)
800    {
801        bool __r = __comp_(__x, __y);
802        if (__r)
803            __do_compare_assert(0, __y, __x);
804        return __r;
805    }
806
807    template <class _LHS, class _RHS>
808    _LIBCPP_CONSTEXPR_AFTER_CXX17
809    inline _LIBCPP_INLINE_VISIBILITY
810    decltype((void)_VSTD::declval<_Compare&>()(
811        _VSTD::declval<_LHS &>(), _VSTD::declval<_RHS &>()))
812    __do_compare_assert(int, _LHS & __l, _RHS & __r) {
813        _LIBCPP_ASSERT(!__comp_(__l, __r),
814            "Comparator does not induce a strict weak ordering");
815    }
816
817    template <class _LHS, class _RHS>
818    _LIBCPP_CONSTEXPR_AFTER_CXX17
819    inline _LIBCPP_INLINE_VISIBILITY
820    void __do_compare_assert(long, _LHS &, _RHS &) {}
821};
822
823#endif // _LIBCPP_DEBUG
824
825template <class _Comp>
826struct __comp_ref_type {
827  // Pass the comparator by lvalue reference. Or in debug mode, using a
828  // debugging wrapper that stores a reference.
829#ifndef _LIBCPP_DEBUG
830  typedef typename add_lvalue_reference<_Comp>::type type;
831#else
832  typedef __debug_less<_Comp> type;
833#endif
834};
835
836// all_of
837
838template <class _InputIterator, class _Predicate>
839_LIBCPP_NODISCARD_EXT inline
840_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
841bool
842all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
843{
844    for (; __first != __last; ++__first)
845        if (!__pred(*__first))
846            return false;
847    return true;
848}
849
850// any_of
851
852template <class _InputIterator, class _Predicate>
853_LIBCPP_NODISCARD_EXT inline
854_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
855bool
856any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
857{
858    for (; __first != __last; ++__first)
859        if (__pred(*__first))
860            return true;
861    return false;
862}
863
864// none_of
865
866template <class _InputIterator, class _Predicate>
867_LIBCPP_NODISCARD_EXT inline
868_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
869bool
870none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
871{
872    for (; __first != __last; ++__first)
873        if (__pred(*__first))
874            return false;
875    return true;
876}
877
878// for_each
879
880template <class _InputIterator, class _Function>
881inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
882_Function
883for_each(_InputIterator __first, _InputIterator __last, _Function __f)
884{
885    for (; __first != __last; ++__first)
886        __f(*__first);
887    return __f;
888}
889
890#if _LIBCPP_STD_VER > 14
891// for_each_n
892
893template <class _InputIterator, class _Size, class _Function>
894inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
895_InputIterator
896for_each_n(_InputIterator __first, _Size __orig_n, _Function __f)
897{
898    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
899    _IntegralSize __n = __orig_n;
900    while (__n > 0)
901    {
902         __f(*__first);
903         ++__first;
904         --__n;
905    }
906    return __first;
907}
908#endif
909
910// find
911
912template <class _InputIterator, class _Tp>
913_LIBCPP_NODISCARD_EXT inline
914_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
915_InputIterator
916find(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
917{
918    for (; __first != __last; ++__first)
919        if (*__first == __value_)
920            break;
921    return __first;
922}
923
924// find_if
925
926template <class _InputIterator, class _Predicate>
927_LIBCPP_NODISCARD_EXT inline
928_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
929_InputIterator
930find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
931{
932    for (; __first != __last; ++__first)
933        if (__pred(*__first))
934            break;
935    return __first;
936}
937
938// find_if_not
939
940template<class _InputIterator, class _Predicate>
941_LIBCPP_NODISCARD_EXT inline
942_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
943_InputIterator
944find_if_not(_InputIterator __first, _InputIterator __last, _Predicate __pred)
945{
946    for (; __first != __last; ++__first)
947        if (!__pred(*__first))
948            break;
949    return __first;
950}
951
952// find_end
953
954template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
955_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
956__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
957           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred,
958           forward_iterator_tag, forward_iterator_tag)
959{
960    // modeled after search algorithm
961    _ForwardIterator1 __r = __last1;  // __last1 is the "default" answer
962    if (__first2 == __last2)
963        return __r;
964    while (true)
965    {
966        while (true)
967        {
968            if (__first1 == __last1)         // if source exhausted return last correct answer
969                return __r;                  //    (or __last1 if never found)
970            if (__pred(*__first1, *__first2))
971                break;
972            ++__first1;
973        }
974        // *__first1 matches *__first2, now match elements after here
975        _ForwardIterator1 __m1 = __first1;
976        _ForwardIterator2 __m2 = __first2;
977        while (true)
978        {
979            if (++__m2 == __last2)
980            {                         // Pattern exhaused, record answer and search for another one
981                __r = __first1;
982                ++__first1;
983                break;
984            }
985            if (++__m1 == __last1)     // Source exhausted, return last answer
986                return __r;
987            if (!__pred(*__m1, *__m2))  // mismatch, restart with a new __first
988            {
989                ++__first1;
990                break;
991            }  // else there is a match, check next elements
992        }
993    }
994}
995
996template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
997_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1
998__find_end(_BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1,
999           _BidirectionalIterator2 __first2, _BidirectionalIterator2 __last2, _BinaryPredicate __pred,
1000           bidirectional_iterator_tag, bidirectional_iterator_tag)
1001{
1002    // modeled after search algorithm (in reverse)
1003    if (__first2 == __last2)
1004        return __last1;  // Everything matches an empty sequence
1005    _BidirectionalIterator1 __l1 = __last1;
1006    _BidirectionalIterator2 __l2 = __last2;
1007    --__l2;
1008    while (true)
1009    {
1010        // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
1011        while (true)
1012        {
1013            if (__first1 == __l1)  // return __last1 if no element matches *__first2
1014                return __last1;
1015            if (__pred(*--__l1, *__l2))
1016                break;
1017        }
1018        // *__l1 matches *__l2, now match elements before here
1019        _BidirectionalIterator1 __m1 = __l1;
1020        _BidirectionalIterator2 __m2 = __l2;
1021        while (true)
1022        {
1023            if (__m2 == __first2)  // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
1024                return __m1;
1025            if (__m1 == __first1)  // Otherwise if source exhaused, pattern not found
1026                return __last1;
1027            if (!__pred(*--__m1, *--__m2))  // if there is a mismatch, restart with a new __l1
1028            {
1029                break;
1030            }  // else there is a match, check next elements
1031        }
1032    }
1033}
1034
1035template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1036_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1
1037__find_end(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1038           _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1039           random_access_iterator_tag, random_access_iterator_tag)
1040{
1041    // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
1042    typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
1043    if (__len2 == 0)
1044        return __last1;
1045    typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
1046    if (__len1 < __len2)
1047        return __last1;
1048    const _RandomAccessIterator1 __s = __first1 + (__len2 - 1);  // End of pattern match can't go before here
1049    _RandomAccessIterator1 __l1 = __last1;
1050    _RandomAccessIterator2 __l2 = __last2;
1051    --__l2;
1052    while (true)
1053    {
1054        while (true)
1055        {
1056            if (__s == __l1)
1057                return __last1;
1058            if (__pred(*--__l1, *__l2))
1059                break;
1060        }
1061        _RandomAccessIterator1 __m1 = __l1;
1062        _RandomAccessIterator2 __m2 = __l2;
1063        while (true)
1064        {
1065            if (__m2 == __first2)
1066                return __m1;
1067                                 // no need to check range on __m1 because __s guarantees we have enough source
1068            if (!__pred(*--__m1, *--__m2))
1069            {
1070                break;
1071            }
1072        }
1073    }
1074}
1075
1076template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1077_LIBCPP_NODISCARD_EXT inline
1078_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1079_ForwardIterator1
1080find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1081         _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1082{
1083    return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>
1084                         (__first1, __last1, __first2, __last2, __pred,
1085                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1086                          typename iterator_traits<_ForwardIterator2>::iterator_category());
1087}
1088
1089template <class _ForwardIterator1, class _ForwardIterator2>
1090_LIBCPP_NODISCARD_EXT inline
1091_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1092_ForwardIterator1
1093find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1094         _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1095{
1096    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1097    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1098    return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1099}
1100
1101// find_first_of
1102
1103template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1104_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator1
1105__find_first_of_ce(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1106              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1107{
1108    for (; __first1 != __last1; ++__first1)
1109        for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1110            if (__pred(*__first1, *__j))
1111                return __first1;
1112    return __last1;
1113}
1114
1115
1116template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1117_LIBCPP_NODISCARD_EXT inline
1118_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1119_ForwardIterator1
1120find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1121              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1122{
1123    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __pred);
1124}
1125
1126template <class _ForwardIterator1, class _ForwardIterator2>
1127_LIBCPP_NODISCARD_EXT inline
1128_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1129_ForwardIterator1
1130find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1131              _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1132{
1133    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1134    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1135    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1136}
1137
1138// adjacent_find
1139
1140template <class _ForwardIterator, class _BinaryPredicate>
1141_LIBCPP_NODISCARD_EXT inline
1142_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1143_ForwardIterator
1144adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
1145{
1146    if (__first != __last)
1147    {
1148        _ForwardIterator __i = __first;
1149        while (++__i != __last)
1150        {
1151            if (__pred(*__first, *__i))
1152                return __first;
1153            __first = __i;
1154        }
1155    }
1156    return __last;
1157}
1158
1159template <class _ForwardIterator>
1160_LIBCPP_NODISCARD_EXT inline
1161_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1162_ForwardIterator
1163adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
1164{
1165    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1166    return _VSTD::adjacent_find(__first, __last, __equal_to<__v>());
1167}
1168
1169// count
1170
1171template <class _InputIterator, class _Tp>
1172_LIBCPP_NODISCARD_EXT inline
1173_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1174typename iterator_traits<_InputIterator>::difference_type
1175count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
1176{
1177    typename iterator_traits<_InputIterator>::difference_type __r(0);
1178    for (; __first != __last; ++__first)
1179        if (*__first == __value_)
1180            ++__r;
1181    return __r;
1182}
1183
1184// count_if
1185
1186template <class _InputIterator, class _Predicate>
1187_LIBCPP_NODISCARD_EXT inline
1188_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1189typename iterator_traits<_InputIterator>::difference_type
1190count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
1191{
1192    typename iterator_traits<_InputIterator>::difference_type __r(0);
1193    for (; __first != __last; ++__first)
1194        if (__pred(*__first))
1195            ++__r;
1196    return __r;
1197}
1198
1199// mismatch
1200
1201template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1202_LIBCPP_NODISCARD_EXT inline
1203_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1204pair<_InputIterator1, _InputIterator2>
1205mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1206         _InputIterator2 __first2, _BinaryPredicate __pred)
1207{
1208    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1209        if (!__pred(*__first1, *__first2))
1210            break;
1211    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1212}
1213
1214template <class _InputIterator1, class _InputIterator2>
1215_LIBCPP_NODISCARD_EXT inline
1216_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1217pair<_InputIterator1, _InputIterator2>
1218mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1219{
1220    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1221    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1222    return _VSTD::mismatch(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1223}
1224
1225#if _LIBCPP_STD_VER > 11
1226template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1227_LIBCPP_NODISCARD_EXT inline
1228_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1229pair<_InputIterator1, _InputIterator2>
1230mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1231         _InputIterator2 __first2, _InputIterator2 __last2,
1232         _BinaryPredicate __pred)
1233{
1234    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1235        if (!__pred(*__first1, *__first2))
1236            break;
1237    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1238}
1239
1240template <class _InputIterator1, class _InputIterator2>
1241_LIBCPP_NODISCARD_EXT inline
1242_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1243pair<_InputIterator1, _InputIterator2>
1244mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1245         _InputIterator2 __first2, _InputIterator2 __last2)
1246{
1247    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1248    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1249    return _VSTD::mismatch(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1250}
1251#endif
1252
1253// equal
1254
1255template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1256_LIBCPP_NODISCARD_EXT inline
1257_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1258bool
1259equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred)
1260{
1261    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1262        if (!__pred(*__first1, *__first2))
1263            return false;
1264    return true;
1265}
1266
1267template <class _InputIterator1, class _InputIterator2>
1268_LIBCPP_NODISCARD_EXT inline
1269_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1270bool
1271equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1272{
1273    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1274    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1275    return _VSTD::equal(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1276}
1277
1278#if _LIBCPP_STD_VER > 11
1279template <class _BinaryPredicate, class _InputIterator1, class _InputIterator2>
1280inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1281bool
1282__equal(_InputIterator1 __first1, _InputIterator1 __last1,
1283        _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred,
1284        input_iterator_tag, input_iterator_tag )
1285{
1286    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1287        if (!__pred(*__first1, *__first2))
1288            return false;
1289    return __first1 == __last1 && __first2 == __last2;
1290}
1291
1292template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1293inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1294bool
1295__equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1296        _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1297      random_access_iterator_tag, random_access_iterator_tag )
1298{
1299    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1300        return false;
1301    return _VSTD::equal<_RandomAccessIterator1, _RandomAccessIterator2,
1302                        typename add_lvalue_reference<_BinaryPredicate>::type>
1303                       (__first1, __last1, __first2, __pred );
1304}
1305
1306template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1307_LIBCPP_NODISCARD_EXT inline
1308_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1309bool
1310equal(_InputIterator1 __first1, _InputIterator1 __last1,
1311      _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred )
1312{
1313    return _VSTD::__equal<typename add_lvalue_reference<_BinaryPredicate>::type>
1314       (__first1, __last1, __first2, __last2, __pred,
1315        typename iterator_traits<_InputIterator1>::iterator_category(),
1316        typename iterator_traits<_InputIterator2>::iterator_category());
1317}
1318
1319template <class _InputIterator1, class _InputIterator2>
1320_LIBCPP_NODISCARD_EXT inline
1321_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1322bool
1323equal(_InputIterator1 __first1, _InputIterator1 __last1,
1324      _InputIterator2 __first2, _InputIterator2 __last2)
1325{
1326    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1327    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1328    return _VSTD::__equal(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
1329        typename iterator_traits<_InputIterator1>::iterator_category(),
1330        typename iterator_traits<_InputIterator2>::iterator_category());
1331}
1332#endif
1333
1334// is_permutation
1335
1336template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1337_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1338is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1339               _ForwardIterator2 __first2, _BinaryPredicate __pred)
1340{
1341//  shorten sequences as much as possible by lopping of any equal prefix
1342    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1343        if (!__pred(*__first1, *__first2))
1344            break;
1345    if (__first1 == __last1)
1346        return true;
1347
1348//  __first1 != __last1 && *__first1 != *__first2
1349    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1350    _D1 __l1 = _VSTD::distance(__first1, __last1);
1351    if (__l1 == _D1(1))
1352        return false;
1353    _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1);
1354    // For each element in [f1, l1) see if there are the same number of
1355    //    equal elements in [f2, l2)
1356    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1357    {
1358    //  Have we already counted the number of *__i in [f1, l1)?
1359        _ForwardIterator1 __match = __first1;
1360        for (; __match != __i; ++__match)
1361            if (__pred(*__match, *__i))
1362                break;
1363        if (__match == __i) {
1364            // Count number of *__i in [f2, l2)
1365            _D1 __c2 = 0;
1366            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1367                if (__pred(*__i, *__j))
1368                    ++__c2;
1369            if (__c2 == 0)
1370                return false;
1371            // Count number of *__i in [__i, l1) (we can start with 1)
1372            _D1 __c1 = 1;
1373            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1374                if (__pred(*__i, *__j))
1375                    ++__c1;
1376            if (__c1 != __c2)
1377                return false;
1378        }
1379    }
1380    return true;
1381}
1382
1383template<class _ForwardIterator1, class _ForwardIterator2>
1384_LIBCPP_NODISCARD_EXT inline
1385_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1386bool
1387is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1388               _ForwardIterator2 __first2)
1389{
1390    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1391    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1392    return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1393}
1394
1395#if _LIBCPP_STD_VER > 11
1396template<class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
1397_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1398__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1399                 _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1400                 _BinaryPredicate __pred,
1401                 forward_iterator_tag, forward_iterator_tag )
1402{
1403//  shorten sequences as much as possible by lopping of any equal prefix
1404    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1405        if (!__pred(*__first1, *__first2))
1406            break;
1407    if (__first1 == __last1)
1408        return __first2 == __last2;
1409    else if (__first2 == __last2)
1410        return false;
1411
1412    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1413    _D1 __l1 = _VSTD::distance(__first1, __last1);
1414
1415    typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2;
1416    _D2 __l2 = _VSTD::distance(__first2, __last2);
1417    if (__l1 != __l2)
1418        return false;
1419
1420    // For each element in [f1, l1) see if there are the same number of
1421    //    equal elements in [f2, l2)
1422    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1423    {
1424    //  Have we already counted the number of *__i in [f1, l1)?
1425        _ForwardIterator1 __match = __first1;
1426        for (; __match != __i; ++__match)
1427            if (__pred(*__match, *__i))
1428                break;
1429        if (__match == __i) {
1430            // Count number of *__i in [f2, l2)
1431            _D1 __c2 = 0;
1432            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1433                if (__pred(*__i, *__j))
1434                    ++__c2;
1435            if (__c2 == 0)
1436                return false;
1437            // Count number of *__i in [__i, l1) (we can start with 1)
1438            _D1 __c1 = 1;
1439            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1440                if (__pred(*__i, *__j))
1441                    ++__c1;
1442            if (__c1 != __c2)
1443                return false;
1444        }
1445    }
1446    return true;
1447}
1448
1449template<class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1450_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1451__is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1,
1452               _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2,
1453               _BinaryPredicate __pred,
1454               random_access_iterator_tag, random_access_iterator_tag )
1455{
1456    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1457        return false;
1458    return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2,
1459                                 typename add_lvalue_reference<_BinaryPredicate>::type>
1460                                (__first1, __last1, __first2, __pred );
1461}
1462
1463template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1464_LIBCPP_NODISCARD_EXT inline
1465_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1466bool
1467is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1468               _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1469               _BinaryPredicate __pred )
1470{
1471    return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>
1472       (__first1, __last1, __first2, __last2, __pred,
1473        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1474        typename iterator_traits<_ForwardIterator2>::iterator_category());
1475}
1476
1477template<class _ForwardIterator1, class _ForwardIterator2>
1478_LIBCPP_NODISCARD_EXT inline
1479_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1480bool
1481is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1482               _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1483{
1484    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1485    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1486    return _VSTD::__is_permutation(__first1, __last1, __first2, __last2,
1487        __equal_to<__v1, __v2>(),
1488        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1489        typename iterator_traits<_ForwardIterator2>::iterator_category());
1490}
1491#endif
1492
1493// search
1494// __search is in <functional>
1495
1496template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1497_LIBCPP_NODISCARD_EXT inline
1498_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1499_ForwardIterator1
1500search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1501       _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1502{
1503    return _VSTD::__search<typename add_lvalue_reference<_BinaryPredicate>::type>
1504                         (__first1, __last1, __first2, __last2, __pred,
1505                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1506                          typename iterator_traits<_ForwardIterator2>::iterator_category())
1507            .first;
1508}
1509
1510template <class _ForwardIterator1, class _ForwardIterator2>
1511_LIBCPP_NODISCARD_EXT inline
1512_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1513_ForwardIterator1
1514search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1515       _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1516{
1517    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1518    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1519    return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1520}
1521
1522
1523#if _LIBCPP_STD_VER > 14
1524template <class _ForwardIterator, class _Searcher>
1525_LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1526_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
1527{ return __s(__f, __l).first; }
1528#endif
1529
1530// search_n
1531
1532template <class _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
1533_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
1534__search_n(_ForwardIterator __first, _ForwardIterator __last,
1535           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, forward_iterator_tag)
1536{
1537    if (__count <= 0)
1538        return __first;
1539    while (true)
1540    {
1541        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1542        while (true)
1543        {
1544            if (__first == __last)  // return __last if no element matches __value_
1545                return __last;
1546            if (__pred(*__first, __value_))
1547                break;
1548            ++__first;
1549        }
1550        // *__first matches __value_, now match elements after here
1551        _ForwardIterator __m = __first;
1552        _Size __c(0);
1553        while (true)
1554        {
1555            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1556                return __first;
1557            if (++__m == __last)  // Otherwise if source exhaused, pattern not found
1558                return __last;
1559            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1560            {
1561                __first = __m;
1562                ++__first;
1563                break;
1564            }  // else there is a match, check next elements
1565        }
1566    }
1567}
1568
1569template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
1570_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
1571__search_n(_RandomAccessIterator __first, _RandomAccessIterator __last,
1572           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, random_access_iterator_tag)
1573{
1574    if (__count <= 0)
1575        return __first;
1576    _Size __len = static_cast<_Size>(__last - __first);
1577    if (__len < __count)
1578        return __last;
1579    const _RandomAccessIterator __s = __last - (__count - 1);  // Start of pattern match can't go beyond here
1580    while (true)
1581    {
1582        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1583        while (true)
1584        {
1585            if (__first >= __s)  // return __last if no element matches __value_
1586                return __last;
1587            if (__pred(*__first, __value_))
1588                break;
1589            ++__first;
1590        }
1591        // *__first matches __value_, now match elements after here
1592        _RandomAccessIterator __m = __first;
1593        _Size __c(0);
1594        while (true)
1595        {
1596            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1597                return __first;
1598             ++__m;          // no need to check range on __m because __s guarantees we have enough source
1599            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1600            {
1601                __first = __m;
1602                ++__first;
1603                break;
1604            }  // else there is a match, check next elements
1605        }
1606    }
1607}
1608
1609template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
1610_LIBCPP_NODISCARD_EXT inline
1611_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1612_ForwardIterator
1613search_n(_ForwardIterator __first, _ForwardIterator __last,
1614         _Size __count, const _Tp& __value_, _BinaryPredicate __pred)
1615{
1616    return _VSTD::__search_n<typename add_lvalue_reference<_BinaryPredicate>::type>
1617           (__first, __last, __convert_to_integral(__count), __value_, __pred,
1618           typename iterator_traits<_ForwardIterator>::iterator_category());
1619}
1620
1621template <class _ForwardIterator, class _Size, class _Tp>
1622_LIBCPP_NODISCARD_EXT inline
1623_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1624_ForwardIterator
1625search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_)
1626{
1627    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1628    return _VSTD::search_n(__first, __last, __convert_to_integral(__count),
1629                           __value_, __equal_to<__v, _Tp>());
1630}
1631
1632// copy
1633template <class _Iter>
1634inline _LIBCPP_INLINE_VISIBILITY
1635_Iter
1636__unwrap_iter(_Iter __i)
1637{
1638    return __i;
1639}
1640
1641template <class _Tp>
1642inline _LIBCPP_INLINE_VISIBILITY
1643typename enable_if
1644<
1645    is_trivially_copy_assignable<_Tp>::value,
1646    _Tp*
1647>::type
1648__unwrap_iter(move_iterator<_Tp*> __i)
1649{
1650    return __i.base();
1651}
1652
1653#if _LIBCPP_DEBUG_LEVEL < 2
1654
1655template <class _Tp>
1656inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1657typename enable_if
1658<
1659    is_trivially_copy_assignable<_Tp>::value,
1660    _Tp*
1661>::type
1662__unwrap_iter(__wrap_iter<_Tp*> __i)
1663{
1664    return __i.base();
1665}
1666
1667template <class _Tp>
1668inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1669typename enable_if
1670<
1671    is_trivially_copy_assignable<_Tp>::value,
1672    const _Tp*
1673>::type
1674__unwrap_iter(__wrap_iter<const _Tp*> __i)
1675{
1676    return __i.base();
1677}
1678
1679#else
1680
1681template <class _Tp>
1682inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1683typename enable_if
1684<
1685    is_trivially_copy_assignable<_Tp>::value,
1686    __wrap_iter<_Tp*>
1687>::type
1688__unwrap_iter(__wrap_iter<_Tp*> __i)
1689{
1690    return __i;
1691}
1692
1693#endif  // _LIBCPP_DEBUG_LEVEL < 2
1694
1695template <class _InputIterator, class _OutputIterator>
1696inline _LIBCPP_INLINE_VISIBILITY
1697_OutputIterator
1698__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1699{
1700    for (; __first != __last; ++__first, (void) ++__result)
1701        *__result = *__first;
1702    return __result;
1703}
1704
1705template <class _Tp, class _Up>
1706inline _LIBCPP_INLINE_VISIBILITY
1707typename enable_if
1708<
1709    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1710    is_trivially_copy_assignable<_Up>::value,
1711    _Up*
1712>::type
1713__copy(_Tp* __first, _Tp* __last, _Up* __result)
1714{
1715    const size_t __n = static_cast<size_t>(__last - __first);
1716    if (__n > 0)
1717        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1718    return __result + __n;
1719}
1720
1721template <class _InputIterator, class _OutputIterator>
1722inline _LIBCPP_INLINE_VISIBILITY
1723_OutputIterator
1724copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1725{
1726    return _VSTD::__copy(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1727}
1728
1729// copy_backward
1730
1731template <class _BidirectionalIterator, class _OutputIterator>
1732inline _LIBCPP_INLINE_VISIBILITY
1733_OutputIterator
1734__copy_backward(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
1735{
1736    while (__first != __last)
1737        *--__result = *--__last;
1738    return __result;
1739}
1740
1741template <class _Tp, class _Up>
1742inline _LIBCPP_INLINE_VISIBILITY
1743typename enable_if
1744<
1745    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1746    is_trivially_copy_assignable<_Up>::value,
1747    _Up*
1748>::type
1749__copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
1750{
1751    const size_t __n = static_cast<size_t>(__last - __first);
1752    if (__n > 0)
1753    {
1754        __result -= __n;
1755        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1756    }
1757    return __result;
1758}
1759
1760template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1761inline _LIBCPP_INLINE_VISIBILITY
1762_BidirectionalIterator2
1763copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1764              _BidirectionalIterator2 __result)
1765{
1766    return _VSTD::__copy_backward(__unwrap_iter(__first),
1767                                  __unwrap_iter(__last),
1768                                  __unwrap_iter(__result));
1769}
1770
1771// copy_if
1772
1773template<class _InputIterator, class _OutputIterator, class _Predicate>
1774inline _LIBCPP_INLINE_VISIBILITY
1775_OutputIterator
1776copy_if(_InputIterator __first, _InputIterator __last,
1777        _OutputIterator __result, _Predicate __pred)
1778{
1779    for (; __first != __last; ++__first)
1780    {
1781        if (__pred(*__first))
1782        {
1783            *__result = *__first;
1784            ++__result;
1785        }
1786    }
1787    return __result;
1788}
1789
1790// copy_n
1791
1792template<class _InputIterator, class _Size, class _OutputIterator>
1793inline _LIBCPP_INLINE_VISIBILITY
1794typename enable_if
1795<
1796    __is_input_iterator<_InputIterator>::value &&
1797   !__is_random_access_iterator<_InputIterator>::value,
1798    _OutputIterator
1799>::type
1800copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1801{
1802    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1803    _IntegralSize __n = __orig_n;
1804    if (__n > 0)
1805    {
1806        *__result = *__first;
1807        ++__result;
1808        for (--__n; __n > 0; --__n)
1809        {
1810            ++__first;
1811            *__result = *__first;
1812            ++__result;
1813        }
1814    }
1815    return __result;
1816}
1817
1818template<class _InputIterator, class _Size, class _OutputIterator>
1819inline _LIBCPP_INLINE_VISIBILITY
1820typename enable_if
1821<
1822    __is_random_access_iterator<_InputIterator>::value,
1823    _OutputIterator
1824>::type
1825copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1826{
1827    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1828    _IntegralSize __n = __orig_n;
1829    return _VSTD::copy(__first, __first + __n, __result);
1830}
1831
1832// move
1833
1834template <class _InputIterator, class _OutputIterator>
1835inline _LIBCPP_INLINE_VISIBILITY
1836_OutputIterator
1837__move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1838{
1839    for (; __first != __last; ++__first, (void) ++__result)
1840        *__result = _VSTD::move(*__first);
1841    return __result;
1842}
1843
1844template <class _Tp, class _Up>
1845inline _LIBCPP_INLINE_VISIBILITY
1846typename enable_if
1847<
1848    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1849    is_trivially_copy_assignable<_Up>::value,
1850    _Up*
1851>::type
1852__move(_Tp* __first, _Tp* __last, _Up* __result)
1853{
1854    const size_t __n = static_cast<size_t>(__last - __first);
1855    if (__n > 0)
1856        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1857    return __result + __n;
1858}
1859
1860template <class _InputIterator, class _OutputIterator>
1861inline _LIBCPP_INLINE_VISIBILITY
1862_OutputIterator
1863move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1864{
1865    return _VSTD::__move(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1866}
1867
1868// move_backward
1869
1870template <class _InputIterator, class _OutputIterator>
1871inline _LIBCPP_INLINE_VISIBILITY
1872_OutputIterator
1873__move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1874{
1875    while (__first != __last)
1876        *--__result = _VSTD::move(*--__last);
1877    return __result;
1878}
1879
1880template <class _Tp, class _Up>
1881inline _LIBCPP_INLINE_VISIBILITY
1882typename enable_if
1883<
1884    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1885    is_trivially_copy_assignable<_Up>::value,
1886    _Up*
1887>::type
1888__move_backward(_Tp* __first, _Tp* __last, _Up* __result)
1889{
1890    const size_t __n = static_cast<size_t>(__last - __first);
1891    if (__n > 0)
1892    {
1893        __result -= __n;
1894        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1895    }
1896    return __result;
1897}
1898
1899template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1900inline _LIBCPP_INLINE_VISIBILITY
1901_BidirectionalIterator2
1902move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1903              _BidirectionalIterator2 __result)
1904{
1905    return _VSTD::__move_backward(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1906}
1907
1908// iter_swap
1909
1910// moved to <type_traits> for better swap / noexcept support
1911
1912// transform
1913
1914template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
1915inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1916_OutputIterator
1917transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
1918{
1919    for (; __first != __last; ++__first, (void) ++__result)
1920        *__result = __op(*__first);
1921    return __result;
1922}
1923
1924template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _BinaryOperation>
1925inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1926_OutputIterator
1927transform(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2,
1928          _OutputIterator __result, _BinaryOperation __binary_op)
1929{
1930    for (; __first1 != __last1; ++__first1, (void) ++__first2, ++__result)
1931        *__result = __binary_op(*__first1, *__first2);
1932    return __result;
1933}
1934
1935// replace
1936
1937template <class _ForwardIterator, class _Tp>
1938inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1939void
1940replace(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __old_value, const _Tp& __new_value)
1941{
1942    for (; __first != __last; ++__first)
1943        if (*__first == __old_value)
1944            *__first = __new_value;
1945}
1946
1947// replace_if
1948
1949template <class _ForwardIterator, class _Predicate, class _Tp>
1950inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1951void
1952replace_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, const _Tp& __new_value)
1953{
1954    for (; __first != __last; ++__first)
1955        if (__pred(*__first))
1956            *__first = __new_value;
1957}
1958
1959// replace_copy
1960
1961template <class _InputIterator, class _OutputIterator, class _Tp>
1962inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1963_OutputIterator
1964replace_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
1965             const _Tp& __old_value, const _Tp& __new_value)
1966{
1967    for (; __first != __last; ++__first, (void) ++__result)
1968        if (*__first == __old_value)
1969            *__result = __new_value;
1970        else
1971            *__result = *__first;
1972    return __result;
1973}
1974
1975// replace_copy_if
1976
1977template <class _InputIterator, class _OutputIterator, class _Predicate, class _Tp>
1978inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1979_OutputIterator
1980replace_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
1981                _Predicate __pred, const _Tp& __new_value)
1982{
1983    for (; __first != __last; ++__first, (void) ++__result)
1984        if (__pred(*__first))
1985            *__result = __new_value;
1986        else
1987            *__result = *__first;
1988    return __result;
1989}
1990
1991// fill_n
1992
1993template <class _OutputIterator, class _Size, class _Tp>
1994inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1995_OutputIterator
1996__fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
1997{
1998    for (; __n > 0; ++__first, (void) --__n)
1999        *__first = __value_;
2000    return __first;
2001}
2002
2003template <class _OutputIterator, class _Size, class _Tp>
2004inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2005_OutputIterator
2006fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
2007{
2008   return _VSTD::__fill_n(__first, __convert_to_integral(__n), __value_);
2009}
2010
2011// fill
2012
2013template <class _ForwardIterator, class _Tp>
2014inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2015void
2016__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, forward_iterator_tag)
2017{
2018    for (; __first != __last; ++__first)
2019        *__first = __value_;
2020}
2021
2022template <class _RandomAccessIterator, class _Tp>
2023inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2024void
2025__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
2026{
2027    _VSTD::fill_n(__first, __last - __first, __value_);
2028}
2029
2030template <class _ForwardIterator, class _Tp>
2031inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2032void
2033fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2034{
2035    _VSTD::__fill(__first, __last, __value_, typename iterator_traits<_ForwardIterator>::iterator_category());
2036}
2037
2038// generate
2039
2040template <class _ForwardIterator, class _Generator>
2041inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2042void
2043generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __gen)
2044{
2045    for (; __first != __last; ++__first)
2046        *__first = __gen();
2047}
2048
2049// generate_n
2050
2051template <class _OutputIterator, class _Size, class _Generator>
2052inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2053_OutputIterator
2054generate_n(_OutputIterator __first, _Size __orig_n, _Generator __gen)
2055{
2056    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
2057    _IntegralSize __n = __orig_n;
2058    for (; __n > 0; ++__first, (void) --__n)
2059        *__first = __gen();
2060    return __first;
2061}
2062
2063// remove
2064
2065template <class _ForwardIterator, class _Tp>
2066_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2067remove(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2068{
2069    __first = _VSTD::find(__first, __last, __value_);
2070    if (__first != __last)
2071    {
2072        _ForwardIterator __i = __first;
2073        while (++__i != __last)
2074        {
2075            if (!(*__i == __value_))
2076            {
2077                *__first = _VSTD::move(*__i);
2078                ++__first;
2079            }
2080        }
2081    }
2082    return __first;
2083}
2084
2085// remove_if
2086
2087template <class _ForwardIterator, class _Predicate>
2088_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2089remove_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
2090{
2091    __first = _VSTD::find_if<_ForwardIterator, typename add_lvalue_reference<_Predicate>::type>
2092                           (__first, __last, __pred);
2093    if (__first != __last)
2094    {
2095        _ForwardIterator __i = __first;
2096        while (++__i != __last)
2097        {
2098            if (!__pred(*__i))
2099            {
2100                *__first = _VSTD::move(*__i);
2101                ++__first;
2102            }
2103        }
2104    }
2105    return __first;
2106}
2107
2108// remove_copy
2109
2110template <class _InputIterator, class _OutputIterator, class _Tp>
2111inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2112_OutputIterator
2113remove_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, const _Tp& __value_)
2114{
2115    for (; __first != __last; ++__first)
2116    {
2117        if (!(*__first == __value_))
2118        {
2119            *__result = *__first;
2120            ++__result;
2121        }
2122    }
2123    return __result;
2124}
2125
2126// remove_copy_if
2127
2128template <class _InputIterator, class _OutputIterator, class _Predicate>
2129inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2130_OutputIterator
2131remove_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _Predicate __pred)
2132{
2133    for (; __first != __last; ++__first)
2134    {
2135        if (!__pred(*__first))
2136        {
2137            *__result = *__first;
2138            ++__result;
2139        }
2140    }
2141    return __result;
2142}
2143
2144// unique
2145
2146template <class _ForwardIterator, class _BinaryPredicate>
2147_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2148unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
2149{
2150    __first = _VSTD::adjacent_find<_ForwardIterator, typename add_lvalue_reference<_BinaryPredicate>::type>
2151                                 (__first, __last, __pred);
2152    if (__first != __last)
2153    {
2154        // ...  a  a  ?  ...
2155        //      f     i
2156        _ForwardIterator __i = __first;
2157        for (++__i; ++__i != __last;)
2158            if (!__pred(*__first, *__i))
2159                *++__first = _VSTD::move(*__i);
2160        ++__first;
2161    }
2162    return __first;
2163}
2164
2165template <class _ForwardIterator>
2166_LIBCPP_NODISCARD_EXT inline
2167_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2168_ForwardIterator
2169unique(_ForwardIterator __first, _ForwardIterator __last)
2170{
2171    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
2172    return _VSTD::unique(__first, __last, __equal_to<__v>());
2173}
2174
2175// unique_copy
2176
2177template <class _BinaryPredicate, class _InputIterator, class _OutputIterator>
2178_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2179__unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2180              input_iterator_tag, output_iterator_tag)
2181{
2182    if (__first != __last)
2183    {
2184        typename iterator_traits<_InputIterator>::value_type __t(*__first);
2185        *__result = __t;
2186        ++__result;
2187        while (++__first != __last)
2188        {
2189            if (!__pred(__t, *__first))
2190            {
2191                __t = *__first;
2192                *__result = __t;
2193                ++__result;
2194            }
2195        }
2196    }
2197    return __result;
2198}
2199
2200template <class _BinaryPredicate, class _ForwardIterator, class _OutputIterator>
2201_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2202__unique_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2203              forward_iterator_tag, output_iterator_tag)
2204{
2205    if (__first != __last)
2206    {
2207        _ForwardIterator __i = __first;
2208        *__result = *__i;
2209        ++__result;
2210        while (++__first != __last)
2211        {
2212            if (!__pred(*__i, *__first))
2213            {
2214                *__result = *__first;
2215                ++__result;
2216                __i = __first;
2217            }
2218        }
2219    }
2220    return __result;
2221}
2222
2223template <class _BinaryPredicate, class _InputIterator, class _ForwardIterator>
2224_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2225__unique_copy(_InputIterator __first, _InputIterator __last, _ForwardIterator __result, _BinaryPredicate __pred,
2226              input_iterator_tag, forward_iterator_tag)
2227{
2228    if (__first != __last)
2229    {
2230        *__result = *__first;
2231        while (++__first != __last)
2232            if (!__pred(*__result, *__first))
2233                *++__result = *__first;
2234        ++__result;
2235    }
2236    return __result;
2237}
2238
2239template <class _InputIterator, class _OutputIterator, class _BinaryPredicate>
2240inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2241_OutputIterator
2242unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred)
2243{
2244    return _VSTD::__unique_copy<typename add_lvalue_reference<_BinaryPredicate>::type>
2245                              (__first, __last, __result, __pred,
2246                               typename iterator_traits<_InputIterator>::iterator_category(),
2247                               typename iterator_traits<_OutputIterator>::iterator_category());
2248}
2249
2250template <class _InputIterator, class _OutputIterator>
2251inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2252_OutputIterator
2253unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
2254{
2255    typedef typename iterator_traits<_InputIterator>::value_type __v;
2256    return _VSTD::unique_copy(__first, __last, __result, __equal_to<__v>());
2257}
2258
2259// reverse
2260
2261template <class _BidirectionalIterator>
2262inline _LIBCPP_INLINE_VISIBILITY
2263void
2264__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
2265{
2266    while (__first != __last)
2267    {
2268        if (__first == --__last)
2269            break;
2270        _VSTD::iter_swap(__first, __last);
2271        ++__first;
2272    }
2273}
2274
2275template <class _RandomAccessIterator>
2276inline _LIBCPP_INLINE_VISIBILITY
2277void
2278__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
2279{
2280    if (__first != __last)
2281        for (; __first < --__last; ++__first)
2282            _VSTD::iter_swap(__first, __last);
2283}
2284
2285template <class _BidirectionalIterator>
2286inline _LIBCPP_INLINE_VISIBILITY
2287void
2288reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
2289{
2290    _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
2291}
2292
2293// reverse_copy
2294
2295template <class _BidirectionalIterator, class _OutputIterator>
2296inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2297_OutputIterator
2298reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
2299{
2300    for (; __first != __last; ++__result)
2301        *__result = *--__last;
2302    return __result;
2303}
2304
2305// rotate
2306
2307template <class _ForwardIterator>
2308_ForwardIterator
2309__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
2310{
2311    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
2312    value_type __tmp = _VSTD::move(*__first);
2313    _ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
2314    *__lm1 = _VSTD::move(__tmp);
2315    return __lm1;
2316}
2317
2318template <class _BidirectionalIterator>
2319_BidirectionalIterator
2320__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
2321{
2322    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
2323    _BidirectionalIterator __lm1 = _VSTD::prev(__last);
2324    value_type __tmp = _VSTD::move(*__lm1);
2325    _BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
2326    *__first = _VSTD::move(__tmp);
2327    return __fp1;
2328}
2329
2330template <class _ForwardIterator>
2331_ForwardIterator
2332__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2333{
2334    _ForwardIterator __i = __middle;
2335    while (true)
2336    {
2337        swap(*__first, *__i);
2338        ++__first;
2339        if (++__i == __last)
2340            break;
2341        if (__first == __middle)
2342            __middle = __i;
2343    }
2344    _ForwardIterator __r = __first;
2345    if (__first != __middle)
2346    {
2347        __i = __middle;
2348        while (true)
2349        {
2350            swap(*__first, *__i);
2351            ++__first;
2352            if (++__i == __last)
2353            {
2354                if (__first == __middle)
2355                    break;
2356                __i = __middle;
2357            }
2358            else if (__first == __middle)
2359                __middle = __i;
2360        }
2361    }
2362    return __r;
2363}
2364
2365template<typename _Integral>
2366inline _LIBCPP_INLINE_VISIBILITY
2367_Integral
2368__algo_gcd(_Integral __x, _Integral __y)
2369{
2370    do
2371    {
2372        _Integral __t = __x % __y;
2373        __x = __y;
2374        __y = __t;
2375    } while (__y);
2376    return __x;
2377}
2378
2379template<typename _RandomAccessIterator>
2380_RandomAccessIterator
2381__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
2382{
2383    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
2384    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
2385
2386    const difference_type __m1 = __middle - __first;
2387    const difference_type __m2 = __last - __middle;
2388    if (__m1 == __m2)
2389    {
2390        _VSTD::swap_ranges(__first, __middle, __middle);
2391        return __middle;
2392    }
2393    const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
2394    for (_RandomAccessIterator __p = __first + __g; __p != __first;)
2395    {
2396        value_type __t(_VSTD::move(*--__p));
2397        _RandomAccessIterator __p1 = __p;
2398        _RandomAccessIterator __p2 = __p1 + __m1;
2399        do
2400        {
2401            *__p1 = _VSTD::move(*__p2);
2402            __p1 = __p2;
2403            const difference_type __d = __last - __p2;
2404            if (__m1 < __d)
2405                __p2 += __m1;
2406            else
2407                __p2 = __first + (__m1 - __d);
2408        } while (__p2 != __p);
2409        *__p1 = _VSTD::move(__t);
2410    }
2411    return __first + __m2;
2412}
2413
2414template <class _ForwardIterator>
2415inline _LIBCPP_INLINE_VISIBILITY
2416_ForwardIterator
2417__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
2418         _VSTD::forward_iterator_tag)
2419{
2420    typedef typename _VSTD::iterator_traits<_ForwardIterator>::value_type value_type;
2421    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2422    {
2423        if (_VSTD::next(__first) == __middle)
2424            return _VSTD::__rotate_left(__first, __last);
2425    }
2426    return _VSTD::__rotate_forward(__first, __middle, __last);
2427}
2428
2429template <class _BidirectionalIterator>
2430inline _LIBCPP_INLINE_VISIBILITY
2431_BidirectionalIterator
2432__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
2433         _VSTD::bidirectional_iterator_tag)
2434{
2435    typedef typename _VSTD::iterator_traits<_BidirectionalIterator>::value_type value_type;
2436    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2437    {
2438        if (_VSTD::next(__first) == __middle)
2439            return _VSTD::__rotate_left(__first, __last);
2440        if (_VSTD::next(__middle) == __last)
2441            return _VSTD::__rotate_right(__first, __last);
2442    }
2443    return _VSTD::__rotate_forward(__first, __middle, __last);
2444}
2445
2446template <class _RandomAccessIterator>
2447inline _LIBCPP_INLINE_VISIBILITY
2448_RandomAccessIterator
2449__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
2450         _VSTD::random_access_iterator_tag)
2451{
2452    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::value_type value_type;
2453    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2454    {
2455        if (_VSTD::next(__first) == __middle)
2456            return _VSTD::__rotate_left(__first, __last);
2457        if (_VSTD::next(__middle) == __last)
2458            return _VSTD::__rotate_right(__first, __last);
2459        return _VSTD::__rotate_gcd(__first, __middle, __last);
2460    }
2461    return _VSTD::__rotate_forward(__first, __middle, __last);
2462}
2463
2464template <class _ForwardIterator>
2465inline _LIBCPP_INLINE_VISIBILITY
2466_ForwardIterator
2467rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2468{
2469    if (__first == __middle)
2470        return __last;
2471    if (__middle == __last)
2472        return __first;
2473    return _VSTD::__rotate(__first, __middle, __last,
2474                           typename _VSTD::iterator_traits<_ForwardIterator>::iterator_category());
2475}
2476
2477// rotate_copy
2478
2479template <class _ForwardIterator, class _OutputIterator>
2480inline _LIBCPP_INLINE_VISIBILITY
2481_OutputIterator
2482rotate_copy(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last, _OutputIterator __result)
2483{
2484    return _VSTD::copy(__first, __middle, _VSTD::copy(__middle, __last, __result));
2485}
2486
2487// min_element
2488
2489template <class _ForwardIterator, class _Compare>
2490_LIBCPP_NODISCARD_EXT inline
2491_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2492_ForwardIterator
2493min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2494{
2495    static_assert(__is_forward_iterator<_ForwardIterator>::value,
2496        "std::min_element requires a ForwardIterator");
2497    if (__first != __last)
2498    {
2499        _ForwardIterator __i = __first;
2500        while (++__i != __last)
2501            if (__comp(*__i, *__first))
2502                __first = __i;
2503    }
2504    return __first;
2505}
2506
2507template <class _ForwardIterator>
2508_LIBCPP_NODISCARD_EXT inline
2509_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2510_ForwardIterator
2511min_element(_ForwardIterator __first, _ForwardIterator __last)
2512{
2513    return _VSTD::min_element(__first, __last,
2514              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2515}
2516
2517// min
2518
2519template <class _Tp, class _Compare>
2520_LIBCPP_NODISCARD_EXT inline
2521_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2522const _Tp&
2523min(const _Tp& __a, const _Tp& __b, _Compare __comp)
2524{
2525    return __comp(__b, __a) ? __b : __a;
2526}
2527
2528template <class _Tp>
2529_LIBCPP_NODISCARD_EXT inline
2530_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2531const _Tp&
2532min(const _Tp& __a, const _Tp& __b)
2533{
2534    return _VSTD::min(__a, __b, __less<_Tp>());
2535}
2536
2537#ifndef _LIBCPP_CXX03_LANG
2538
2539template<class _Tp, class _Compare>
2540_LIBCPP_NODISCARD_EXT inline
2541_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2542_Tp
2543min(initializer_list<_Tp> __t, _Compare __comp)
2544{
2545    return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
2546}
2547
2548template<class _Tp>
2549_LIBCPP_NODISCARD_EXT inline
2550_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2551_Tp
2552min(initializer_list<_Tp> __t)
2553{
2554    return *_VSTD::min_element(__t.begin(), __t.end(), __less<_Tp>());
2555}
2556
2557#endif  // _LIBCPP_CXX03_LANG
2558
2559// max_element
2560
2561template <class _ForwardIterator, class _Compare>
2562_LIBCPP_NODISCARD_EXT inline
2563_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2564_ForwardIterator
2565max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2566{
2567    static_assert(__is_forward_iterator<_ForwardIterator>::value,
2568        "std::max_element requires a ForwardIterator");
2569    if (__first != __last)
2570    {
2571        _ForwardIterator __i = __first;
2572        while (++__i != __last)
2573            if (__comp(*__first, *__i))
2574                __first = __i;
2575    }
2576    return __first;
2577}
2578
2579
2580template <class _ForwardIterator>
2581_LIBCPP_NODISCARD_EXT inline
2582_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2583_ForwardIterator
2584max_element(_ForwardIterator __first, _ForwardIterator __last)
2585{
2586    return _VSTD::max_element(__first, __last,
2587              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2588}
2589
2590// max
2591
2592template <class _Tp, class _Compare>
2593_LIBCPP_NODISCARD_EXT inline
2594_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2595const _Tp&
2596max(const _Tp& __a, const _Tp& __b, _Compare __comp)
2597{
2598    return __comp(__a, __b) ? __b : __a;
2599}
2600
2601template <class _Tp>
2602_LIBCPP_NODISCARD_EXT inline
2603_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2604const _Tp&
2605max(const _Tp& __a, const _Tp& __b)
2606{
2607    return _VSTD::max(__a, __b, __less<_Tp>());
2608}
2609
2610#ifndef _LIBCPP_CXX03_LANG
2611
2612template<class _Tp, class _Compare>
2613_LIBCPP_NODISCARD_EXT inline
2614_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2615_Tp
2616max(initializer_list<_Tp> __t, _Compare __comp)
2617{
2618    return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
2619}
2620
2621template<class _Tp>
2622_LIBCPP_NODISCARD_EXT inline
2623_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2624_Tp
2625max(initializer_list<_Tp> __t)
2626{
2627    return *_VSTD::max_element(__t.begin(), __t.end(), __less<_Tp>());
2628}
2629
2630#endif  // _LIBCPP_CXX03_LANG
2631
2632#if _LIBCPP_STD_VER > 14
2633// clamp
2634template<class _Tp, class _Compare>
2635_LIBCPP_NODISCARD_EXT inline
2636_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2637const _Tp&
2638clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
2639{
2640    _LIBCPP_ASSERT(!__comp(__hi, __lo), "Bad bounds passed to std::clamp");
2641    return __comp(__v, __lo) ? __lo : __comp(__hi, __v) ? __hi : __v;
2642
2643}
2644
2645template<class _Tp>
2646_LIBCPP_NODISCARD_EXT inline
2647_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2648const _Tp&
2649clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi)
2650{
2651    return _VSTD::clamp(__v, __lo, __hi, __less<_Tp>());
2652}
2653#endif
2654
2655// minmax_element
2656
2657template <class _ForwardIterator, class _Compare>
2658_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX11
2659std::pair<_ForwardIterator, _ForwardIterator>
2660minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2661{
2662  static_assert(__is_forward_iterator<_ForwardIterator>::value,
2663        "std::minmax_element requires a ForwardIterator");
2664  std::pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
2665  if (__first != __last)
2666  {
2667      if (++__first != __last)
2668      {
2669          if (__comp(*__first, *__result.first))
2670              __result.first = __first;
2671          else
2672              __result.second = __first;
2673          while (++__first != __last)
2674          {
2675              _ForwardIterator __i = __first;
2676              if (++__first == __last)
2677              {
2678                  if (__comp(*__i, *__result.first))
2679                      __result.first = __i;
2680                  else if (!__comp(*__i, *__result.second))
2681                      __result.second = __i;
2682                  break;
2683              }
2684              else
2685              {
2686                  if (__comp(*__first, *__i))
2687                  {
2688                      if (__comp(*__first, *__result.first))
2689                          __result.first = __first;
2690                      if (!__comp(*__i, *__result.second))
2691                          __result.second = __i;
2692                  }
2693                  else
2694                  {
2695                      if (__comp(*__i, *__result.first))
2696                          __result.first = __i;
2697                      if (!__comp(*__first, *__result.second))
2698                          __result.second = __first;
2699                  }
2700              }
2701          }
2702      }
2703  }
2704  return __result;
2705}
2706
2707template <class _ForwardIterator>
2708_LIBCPP_NODISCARD_EXT inline
2709_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2710std::pair<_ForwardIterator, _ForwardIterator>
2711minmax_element(_ForwardIterator __first, _ForwardIterator __last)
2712{
2713    return _VSTD::minmax_element(__first, __last,
2714              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2715}
2716
2717// minmax
2718
2719template<class _Tp, class _Compare>
2720_LIBCPP_NODISCARD_EXT inline
2721_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2722pair<const _Tp&, const _Tp&>
2723minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
2724{
2725    return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a) :
2726                              pair<const _Tp&, const _Tp&>(__a, __b);
2727}
2728
2729template<class _Tp>
2730_LIBCPP_NODISCARD_EXT inline
2731_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2732pair<const _Tp&, const _Tp&>
2733minmax(const _Tp& __a, const _Tp& __b)
2734{
2735    return _VSTD::minmax(__a, __b, __less<_Tp>());
2736}
2737
2738#ifndef _LIBCPP_CXX03_LANG
2739
2740template<class _Tp, class _Compare>
2741_LIBCPP_NODISCARD_EXT inline
2742_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2743pair<_Tp, _Tp>
2744minmax(initializer_list<_Tp> __t, _Compare __comp)
2745{
2746    typedef typename initializer_list<_Tp>::const_iterator _Iter;
2747    _Iter __first = __t.begin();
2748    _Iter __last  = __t.end();
2749    std::pair<_Tp, _Tp> __result(*__first, *__first);
2750
2751    ++__first;
2752    if (__t.size() % 2 == 0)
2753    {
2754        if (__comp(*__first,  __result.first))
2755            __result.first  = *__first;
2756        else
2757            __result.second = *__first;
2758        ++__first;
2759    }
2760
2761    while (__first != __last)
2762    {
2763        _Tp __prev = *__first++;
2764        if (__comp(*__first, __prev)) {
2765            if ( __comp(*__first, __result.first)) __result.first  = *__first;
2766            if (!__comp(__prev, __result.second))  __result.second = __prev;
2767            }
2768        else {
2769            if ( __comp(__prev, __result.first))    __result.first  = __prev;
2770            if (!__comp(*__first, __result.second)) __result.second = *__first;
2771            }
2772
2773        __first++;
2774    }
2775    return __result;
2776}
2777
2778template<class _Tp>
2779_LIBCPP_NODISCARD_EXT inline
2780_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2781pair<_Tp, _Tp>
2782minmax(initializer_list<_Tp> __t)
2783{
2784    return _VSTD::minmax(__t, __less<_Tp>());
2785}
2786
2787#endif  // _LIBCPP_CXX03_LANG
2788
2789// random_shuffle
2790
2791// __independent_bits_engine
2792
2793template <unsigned long long _Xp, size_t _Rp>
2794struct __log2_imp
2795{
2796    static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
2797                                           : __log2_imp<_Xp, _Rp - 1>::value;
2798};
2799
2800template <unsigned long long _Xp>
2801struct __log2_imp<_Xp, 0>
2802{
2803    static const size_t value = 0;
2804};
2805
2806template <size_t _Rp>
2807struct __log2_imp<0, _Rp>
2808{
2809    static const size_t value = _Rp + 1;
2810};
2811
2812template <class _UIntType, _UIntType _Xp>
2813struct __log2
2814{
2815    static const size_t value = __log2_imp<_Xp,
2816                                         sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
2817};
2818
2819template<class _Engine, class _UIntType>
2820class __independent_bits_engine
2821{
2822public:
2823    // types
2824    typedef _UIntType result_type;
2825
2826private:
2827    typedef typename _Engine::result_type _Engine_result_type;
2828    typedef typename conditional
2829        <
2830            sizeof(_Engine_result_type) <= sizeof(result_type),
2831                result_type,
2832                _Engine_result_type
2833        >::type _Working_result_type;
2834
2835    _Engine& __e_;
2836    size_t __w_;
2837    size_t __w0_;
2838    size_t __n_;
2839    size_t __n0_;
2840    _Working_result_type __y0_;
2841    _Working_result_type __y1_;
2842    _Engine_result_type __mask0_;
2843    _Engine_result_type __mask1_;
2844
2845#ifdef _LIBCPP_CXX03_LANG
2846    static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
2847                                          + _Working_result_type(1);
2848#else
2849    static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
2850                                                      + _Working_result_type(1);
2851#endif
2852    static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
2853    static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
2854    static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
2855
2856public:
2857    // constructors and seeding functions
2858    __independent_bits_engine(_Engine& __e, size_t __w);
2859
2860    // generating functions
2861    result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
2862
2863private:
2864    result_type __eval(false_type);
2865    result_type __eval(true_type);
2866};
2867
2868template<class _Engine, class _UIntType>
2869__independent_bits_engine<_Engine, _UIntType>
2870    ::__independent_bits_engine(_Engine& __e, size_t __w)
2871        : __e_(__e),
2872          __w_(__w)
2873{
2874    __n_ = __w_ / __m + (__w_ % __m != 0);
2875    __w0_ = __w_ / __n_;
2876    if (_Rp == 0)
2877        __y0_ = _Rp;
2878    else if (__w0_ < _WDt)
2879        __y0_ = (_Rp >> __w0_) << __w0_;
2880    else
2881        __y0_ = 0;
2882    if (_Rp - __y0_ > __y0_ / __n_)
2883    {
2884        ++__n_;
2885        __w0_ = __w_ / __n_;
2886        if (__w0_ < _WDt)
2887            __y0_ = (_Rp >> __w0_) << __w0_;
2888        else
2889            __y0_ = 0;
2890    }
2891    __n0_ = __n_ - __w_ % __n_;
2892    if (__w0_ < _WDt - 1)
2893        __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
2894    else
2895        __y1_ = 0;
2896    __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
2897                          _Engine_result_type(0);
2898    __mask1_ = __w0_ < _EDt - 1 ?
2899                               _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) :
2900                               _Engine_result_type(~0);
2901}
2902
2903template<class _Engine, class _UIntType>
2904inline
2905_UIntType
2906__independent_bits_engine<_Engine, _UIntType>::__eval(false_type)
2907{
2908    return static_cast<result_type>(__e_() & __mask0_);
2909}
2910
2911template<class _Engine, class _UIntType>
2912_UIntType
2913__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
2914{
2915    const size_t _WRt = numeric_limits<result_type>::digits;
2916    result_type _Sp = 0;
2917    for (size_t __k = 0; __k < __n0_; ++__k)
2918    {
2919        _Engine_result_type __u;
2920        do
2921        {
2922            __u = __e_() - _Engine::min();
2923        } while (__u >= __y0_);
2924        if (__w0_ < _WRt)
2925            _Sp <<= __w0_;
2926        else
2927            _Sp = 0;
2928        _Sp += __u & __mask0_;
2929    }
2930    for (size_t __k = __n0_; __k < __n_; ++__k)
2931    {
2932        _Engine_result_type __u;
2933        do
2934        {
2935            __u = __e_() - _Engine::min();
2936        } while (__u >= __y1_);
2937        if (__w0_ < _WRt - 1)
2938            _Sp <<= __w0_ + 1;
2939        else
2940            _Sp = 0;
2941        _Sp += __u & __mask1_;
2942    }
2943    return _Sp;
2944}
2945
2946// uniform_int_distribution
2947
2948template<class _IntType = int>
2949class uniform_int_distribution
2950{
2951public:
2952    // types
2953    typedef _IntType result_type;
2954
2955    class param_type
2956    {
2957        result_type __a_;
2958        result_type __b_;
2959    public:
2960        typedef uniform_int_distribution distribution_type;
2961
2962        explicit param_type(result_type __a = 0,
2963                            result_type __b = numeric_limits<result_type>::max())
2964            : __a_(__a), __b_(__b) {}
2965
2966        result_type a() const {return __a_;}
2967        result_type b() const {return __b_;}
2968
2969        friend bool operator==(const param_type& __x, const param_type& __y)
2970            {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
2971        friend bool operator!=(const param_type& __x, const param_type& __y)
2972            {return !(__x == __y);}
2973    };
2974
2975private:
2976    param_type __p_;
2977
2978public:
2979    // constructors and reset functions
2980    explicit uniform_int_distribution(result_type __a = 0,
2981                                      result_type __b = numeric_limits<result_type>::max())
2982        : __p_(param_type(__a, __b)) {}
2983    explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
2984    void reset() {}
2985
2986    // generating functions
2987    template<class _URNG> result_type operator()(_URNG& __g)
2988        {return (*this)(__g, __p_);}
2989    template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
2990
2991    // property functions
2992    result_type a() const {return __p_.a();}
2993    result_type b() const {return __p_.b();}
2994
2995    param_type param() const {return __p_;}
2996    void param(const param_type& __p) {__p_ = __p;}
2997
2998    result_type min() const {return a();}
2999    result_type max() const {return b();}
3000
3001    friend bool operator==(const uniform_int_distribution& __x,
3002                           const uniform_int_distribution& __y)
3003        {return __x.__p_ == __y.__p_;}
3004    friend bool operator!=(const uniform_int_distribution& __x,
3005                           const uniform_int_distribution& __y)
3006            {return !(__x == __y);}
3007};
3008
3009template<class _IntType>
3010template<class _URNG>
3011typename uniform_int_distribution<_IntType>::result_type
3012uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
3013_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
3014{
3015    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
3016                                            uint32_t, uint64_t>::type _UIntType;
3017    const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
3018    if (_Rp == 1)
3019        return __p.a();
3020    const size_t _Dt = numeric_limits<_UIntType>::digits;
3021    typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
3022    if (_Rp == 0)
3023        return static_cast<result_type>(_Eng(__g, _Dt)());
3024    size_t __w = _Dt - __clz(_Rp) - 1;
3025    if ((_Rp & (std::numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
3026        ++__w;
3027    _Eng __e(__g, __w);
3028    _UIntType __u;
3029    do
3030    {
3031        __u = __e();
3032    } while (__u >= _Rp);
3033    return static_cast<result_type>(__u + __p.a());
3034}
3035
3036#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) \
3037  || defined(_LIBCPP_BUILDING_LIBRARY)
3038class _LIBCPP_TYPE_VIS __rs_default;
3039
3040_LIBCPP_FUNC_VIS __rs_default __rs_get();
3041
3042class _LIBCPP_TYPE_VIS __rs_default
3043{
3044    static unsigned __c_;
3045
3046    __rs_default();
3047public:
3048    typedef uint_fast32_t result_type;
3049
3050    static const result_type _Min = 0;
3051    static const result_type _Max = 0xFFFFFFFF;
3052
3053    __rs_default(const __rs_default&);
3054    ~__rs_default();
3055
3056    result_type operator()();
3057
3058    static _LIBCPP_CONSTEXPR result_type min() {return _Min;}
3059    static _LIBCPP_CONSTEXPR result_type max() {return _Max;}
3060
3061    friend _LIBCPP_FUNC_VIS __rs_default __rs_get();
3062};
3063
3064_LIBCPP_FUNC_VIS __rs_default __rs_get();
3065
3066template <class _RandomAccessIterator>
3067_LIBCPP_DEPRECATED_IN_CXX14 void
3068random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
3069{
3070    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3071    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3072    typedef typename _Dp::param_type _Pp;
3073    difference_type __d = __last - __first;
3074    if (__d > 1)
3075    {
3076        _Dp __uid;
3077        __rs_default __g = __rs_get();
3078        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
3079        {
3080            difference_type __i = __uid(__g, _Pp(0, __d));
3081            if (__i != difference_type(0))
3082                swap(*__first, *(__first + __i));
3083        }
3084    }
3085}
3086
3087template <class _RandomAccessIterator, class _RandomNumberGenerator>
3088_LIBCPP_DEPRECATED_IN_CXX14 void
3089random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3090#ifndef _LIBCPP_CXX03_LANG
3091               _RandomNumberGenerator&& __rand)
3092#else
3093               _RandomNumberGenerator& __rand)
3094#endif
3095{
3096    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3097    difference_type __d = __last - __first;
3098    if (__d > 1)
3099    {
3100        for (--__last; __first < __last; ++__first, (void) --__d)
3101        {
3102            difference_type __i = __rand(__d);
3103            if (__i != difference_type(0))
3104              swap(*__first, *(__first + __i));
3105        }
3106    }
3107}
3108#endif
3109
3110template <class _PopulationIterator, class _SampleIterator, class _Distance,
3111          class _UniformRandomNumberGenerator>
3112_LIBCPP_INLINE_VISIBILITY
3113_SampleIterator __sample(_PopulationIterator __first,
3114                         _PopulationIterator __last, _SampleIterator __output_iter,
3115                         _Distance __n,
3116                         _UniformRandomNumberGenerator & __g,
3117                         input_iterator_tag) {
3118
3119  _Distance __k = 0;
3120  for (; __first != __last && __k < __n; ++__first, (void)++__k)
3121    __output_iter[__k] = *__first;
3122  _Distance __sz = __k;
3123  for (; __first != __last; ++__first, (void)++__k) {
3124    _Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);
3125    if (__r < __sz)
3126      __output_iter[__r] = *__first;
3127  }
3128  return __output_iter + _VSTD::min(__n, __k);
3129}
3130
3131template <class _PopulationIterator, class _SampleIterator, class _Distance,
3132          class _UniformRandomNumberGenerator>
3133_LIBCPP_INLINE_VISIBILITY
3134_SampleIterator __sample(_PopulationIterator __first,
3135                         _PopulationIterator __last, _SampleIterator __output_iter,
3136                         _Distance __n,
3137                         _UniformRandomNumberGenerator& __g,
3138                         forward_iterator_tag) {
3139  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
3140  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
3141    _Distance __r =
3142        _VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
3143    if (__r < __n) {
3144      *__output_iter++ = *__first;
3145      --__n;
3146    }
3147  }
3148  return __output_iter;
3149}
3150
3151template <class _PopulationIterator, class _SampleIterator, class _Distance,
3152          class _UniformRandomNumberGenerator>
3153_LIBCPP_INLINE_VISIBILITY
3154_SampleIterator __sample(_PopulationIterator __first,
3155                         _PopulationIterator __last, _SampleIterator __output_iter,
3156                         _Distance __n, _UniformRandomNumberGenerator& __g) {
3157  typedef typename iterator_traits<_PopulationIterator>::iterator_category
3158        _PopCategory;
3159  typedef typename iterator_traits<_PopulationIterator>::difference_type
3160        _Difference;
3161  static_assert(__is_forward_iterator<_PopulationIterator>::value ||
3162                __is_random_access_iterator<_SampleIterator>::value,
3163                "SampleIterator must meet the requirements of RandomAccessIterator");
3164  typedef typename common_type<_Distance, _Difference>::type _CommonType;
3165  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
3166  return _VSTD::__sample(
3167      __first, __last, __output_iter, _CommonType(__n),
3168      __g, _PopCategory());
3169}
3170
3171#if _LIBCPP_STD_VER > 14
3172template <class _PopulationIterator, class _SampleIterator, class _Distance,
3173          class _UniformRandomNumberGenerator>
3174inline _LIBCPP_INLINE_VISIBILITY
3175_SampleIterator sample(_PopulationIterator __first,
3176                       _PopulationIterator __last, _SampleIterator __output_iter,
3177                       _Distance __n, _UniformRandomNumberGenerator&& __g) {
3178    return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
3179}
3180#endif // _LIBCPP_STD_VER > 14
3181
3182template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
3183    void shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3184#ifndef _LIBCPP_CXX03_LANG
3185                 _UniformRandomNumberGenerator&& __g)
3186#else
3187                 _UniformRandomNumberGenerator& __g)
3188#endif
3189{
3190    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3191    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3192    typedef typename _Dp::param_type _Pp;
3193    difference_type __d = __last - __first;
3194    if (__d > 1)
3195    {
3196        _Dp __uid;
3197        for (--__last, --__d; __first < __last; ++__first, --__d)
3198        {
3199            difference_type __i = __uid(__g, _Pp(0, __d));
3200            if (__i != difference_type(0))
3201                swap(*__first, *(__first + __i));
3202        }
3203    }
3204}
3205
3206template <class _InputIterator, class _Predicate>
3207_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
3208is_partitioned(_InputIterator __first, _InputIterator __last, _Predicate __pred)
3209{
3210    for (; __first != __last; ++__first)
3211        if (!__pred(*__first))
3212            break;
3213    if ( __first == __last )
3214        return true;
3215    ++__first;
3216    for (; __first != __last; ++__first)
3217        if (__pred(*__first))
3218            return false;
3219    return true;
3220}
3221
3222// partition
3223
3224template <class _Predicate, class _ForwardIterator>
3225_ForwardIterator
3226__partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag)
3227{
3228    while (true)
3229    {
3230        if (__first == __last)
3231            return __first;
3232        if (!__pred(*__first))
3233            break;
3234        ++__first;
3235    }
3236    for (_ForwardIterator __p = __first; ++__p != __last;)
3237    {
3238        if (__pred(*__p))
3239        {
3240            swap(*__first, *__p);
3241            ++__first;
3242        }
3243    }
3244    return __first;
3245}
3246
3247template <class _Predicate, class _BidirectionalIterator>
3248_BidirectionalIterator
3249__partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3250            bidirectional_iterator_tag)
3251{
3252    while (true)
3253    {
3254        while (true)
3255        {
3256            if (__first == __last)
3257                return __first;
3258            if (!__pred(*__first))
3259                break;
3260            ++__first;
3261        }
3262        do
3263        {
3264            if (__first == --__last)
3265                return __first;
3266        } while (!__pred(*__last));
3267        swap(*__first, *__last);
3268        ++__first;
3269    }
3270}
3271
3272template <class _ForwardIterator, class _Predicate>
3273inline _LIBCPP_INLINE_VISIBILITY
3274_ForwardIterator
3275partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3276{
3277    return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type>
3278                            (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3279}
3280
3281// partition_copy
3282
3283template <class _InputIterator, class _OutputIterator1,
3284          class _OutputIterator2, class _Predicate>
3285_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_OutputIterator1, _OutputIterator2>
3286partition_copy(_InputIterator __first, _InputIterator __last,
3287               _OutputIterator1 __out_true, _OutputIterator2 __out_false,
3288               _Predicate __pred)
3289{
3290    for (; __first != __last; ++__first)
3291    {
3292        if (__pred(*__first))
3293        {
3294            *__out_true = *__first;
3295            ++__out_true;
3296        }
3297        else
3298        {
3299            *__out_false = *__first;
3300            ++__out_false;
3301        }
3302    }
3303    return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
3304}
3305
3306// partition_point
3307
3308template<class _ForwardIterator, class _Predicate>
3309_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3310partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3311{
3312    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3313    difference_type __len = _VSTD::distance(__first, __last);
3314    while (__len != 0)
3315    {
3316        difference_type __l2 = _VSTD::__half_positive(__len);
3317        _ForwardIterator __m = __first;
3318        _VSTD::advance(__m, __l2);
3319        if (__pred(*__m))
3320        {
3321            __first = ++__m;
3322            __len -= __l2 + 1;
3323        }
3324        else
3325            __len = __l2;
3326    }
3327    return __first;
3328}
3329
3330// stable_partition
3331
3332template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair>
3333_ForwardIterator
3334__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3335                   _Distance __len, _Pair __p, forward_iterator_tag __fit)
3336{
3337    // *__first is known to be false
3338    // __len >= 1
3339    if (__len == 1)
3340        return __first;
3341    if (__len == 2)
3342    {
3343        _ForwardIterator __m = __first;
3344        if (__pred(*++__m))
3345        {
3346            swap(*__first, *__m);
3347            return __m;
3348        }
3349        return __first;
3350    }
3351    if (__len <= __p.second)
3352    {   // The buffer is big enough to use
3353        typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3354        __destruct_n __d(0);
3355        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3356        // Move the falses into the temporary buffer, and the trues to the front of the line
3357        // Update __first to always point to the end of the trues
3358        value_type* __t = __p.first;
3359        ::new(__t) value_type(_VSTD::move(*__first));
3360        __d.__incr((value_type*)0);
3361        ++__t;
3362        _ForwardIterator __i = __first;
3363        while (++__i != __last)
3364        {
3365            if (__pred(*__i))
3366            {
3367                *__first = _VSTD::move(*__i);
3368                ++__first;
3369            }
3370            else
3371            {
3372                ::new(__t) value_type(_VSTD::move(*__i));
3373                __d.__incr((value_type*)0);
3374                ++__t;
3375            }
3376        }
3377        // All trues now at start of range, all falses in buffer
3378        // Move falses back into range, but don't mess up __first which points to first false
3379        __i = __first;
3380        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3381            *__i = _VSTD::move(*__t2);
3382        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3383        return __first;
3384    }
3385    // Else not enough buffer, do in place
3386    // __len >= 3
3387    _ForwardIterator __m = __first;
3388    _Distance __len2 = __len / 2;  // __len2 >= 2
3389    _VSTD::advance(__m, __len2);
3390    // recurse on [__first, __m), *__first know to be false
3391    // F?????????????????
3392    // f       m         l
3393    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3394    _ForwardIterator __first_false = __stable_partition<_PredRef>(__first, __m, __pred, __len2, __p, __fit);
3395    // TTTFFFFF??????????
3396    // f  ff   m         l
3397    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3398    _ForwardIterator __m1 = __m;
3399    _ForwardIterator __second_false = __last;
3400    _Distance __len_half = __len - __len2;
3401    while (__pred(*__m1))
3402    {
3403        if (++__m1 == __last)
3404            goto __second_half_done;
3405        --__len_half;
3406    }
3407    // TTTFFFFFTTTF??????
3408    // f  ff   m  m1     l
3409    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __fit);
3410__second_half_done:
3411    // TTTFFFFFTTTTTFFFFF
3412    // f  ff   m    sf   l
3413    return _VSTD::rotate(__first_false, __m, __second_false);
3414    // TTTTTTTTFFFFFFFFFF
3415    //         |
3416}
3417
3418struct __return_temporary_buffer
3419{
3420    template <class _Tp>
3421    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
3422};
3423
3424template <class _Predicate, class _ForwardIterator>
3425_ForwardIterator
3426__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3427                   forward_iterator_tag)
3428{
3429    const unsigned __alloc_limit = 3;  // might want to make this a function of trivial assignment
3430    // Either prove all true and return __first or point to first false
3431    while (true)
3432    {
3433        if (__first == __last)
3434            return __first;
3435        if (!__pred(*__first))
3436            break;
3437        ++__first;
3438    }
3439    // We now have a reduced range [__first, __last)
3440    // *__first is known to be false
3441    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3442    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3443    difference_type __len = _VSTD::distance(__first, __last);
3444    pair<value_type*, ptrdiff_t> __p(0, 0);
3445    unique_ptr<value_type, __return_temporary_buffer> __h;
3446    if (__len >= __alloc_limit)
3447    {
3448        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3449        __h.reset(__p.first);
3450    }
3451    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3452                             (__first, __last, __pred, __len, __p, forward_iterator_tag());
3453}
3454
3455template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair>
3456_BidirectionalIterator
3457__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3458                   _Distance __len, _Pair __p, bidirectional_iterator_tag __bit)
3459{
3460    // *__first is known to be false
3461    // *__last is known to be true
3462    // __len >= 2
3463    if (__len == 2)
3464    {
3465        swap(*__first, *__last);
3466        return __last;
3467    }
3468    if (__len == 3)
3469    {
3470        _BidirectionalIterator __m = __first;
3471        if (__pred(*++__m))
3472        {
3473            swap(*__first, *__m);
3474            swap(*__m, *__last);
3475            return __last;
3476        }
3477        swap(*__m, *__last);
3478        swap(*__first, *__m);
3479        return __m;
3480    }
3481    if (__len <= __p.second)
3482    {   // The buffer is big enough to use
3483        typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3484        __destruct_n __d(0);
3485        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3486        // Move the falses into the temporary buffer, and the trues to the front of the line
3487        // Update __first to always point to the end of the trues
3488        value_type* __t = __p.first;
3489        ::new(__t) value_type(_VSTD::move(*__first));
3490        __d.__incr((value_type*)0);
3491        ++__t;
3492        _BidirectionalIterator __i = __first;
3493        while (++__i != __last)
3494        {
3495            if (__pred(*__i))
3496            {
3497                *__first = _VSTD::move(*__i);
3498                ++__first;
3499            }
3500            else
3501            {
3502                ::new(__t) value_type(_VSTD::move(*__i));
3503                __d.__incr((value_type*)0);
3504                ++__t;
3505            }
3506        }
3507        // move *__last, known to be true
3508        *__first = _VSTD::move(*__i);
3509        __i = ++__first;
3510        // All trues now at start of range, all falses in buffer
3511        // Move falses back into range, but don't mess up __first which points to first false
3512        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3513            *__i = _VSTD::move(*__t2);
3514        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3515        return __first;
3516    }
3517    // Else not enough buffer, do in place
3518    // __len >= 4
3519    _BidirectionalIterator __m = __first;
3520    _Distance __len2 = __len / 2;  // __len2 >= 2
3521    _VSTD::advance(__m, __len2);
3522    // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false
3523    // F????????????????T
3524    // f       m        l
3525    _BidirectionalIterator __m1 = __m;
3526    _BidirectionalIterator __first_false = __first;
3527    _Distance __len_half = __len2;
3528    while (!__pred(*--__m1))
3529    {
3530        if (__m1 == __first)
3531            goto __first_half_done;
3532        --__len_half;
3533    }
3534    // F???TFFF?????????T
3535    // f   m1  m        l
3536    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3537    __first_false = __stable_partition<_PredRef>(__first, __m1, __pred, __len_half, __p, __bit);
3538__first_half_done:
3539    // TTTFFFFF?????????T
3540    // f  ff   m        l
3541    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3542    __m1 = __m;
3543    _BidirectionalIterator __second_false = __last;
3544    ++__second_false;
3545    __len_half = __len - __len2;
3546    while (__pred(*__m1))
3547    {
3548        if (++__m1 == __last)
3549            goto __second_half_done;
3550        --__len_half;
3551    }
3552    // TTTFFFFFTTTF?????T
3553    // f  ff   m  m1    l
3554    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __bit);
3555__second_half_done:
3556    // TTTFFFFFTTTTTFFFFF
3557    // f  ff   m    sf  l
3558    return _VSTD::rotate(__first_false, __m, __second_false);
3559    // TTTTTTTTFFFFFFFFFF
3560    //         |
3561}
3562
3563template <class _Predicate, class _BidirectionalIterator>
3564_BidirectionalIterator
3565__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3566                   bidirectional_iterator_tag)
3567{
3568    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
3569    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3570    const difference_type __alloc_limit = 4;  // might want to make this a function of trivial assignment
3571    // Either prove all true and return __first or point to first false
3572    while (true)
3573    {
3574        if (__first == __last)
3575            return __first;
3576        if (!__pred(*__first))
3577            break;
3578        ++__first;
3579    }
3580    // __first points to first false, everything prior to __first is already set.
3581    // Either prove [__first, __last) is all false and return __first, or point __last to last true
3582    do
3583    {
3584        if (__first == --__last)
3585            return __first;
3586    } while (!__pred(*__last));
3587    // We now have a reduced range [__first, __last]
3588    // *__first is known to be false
3589    // *__last is known to be true
3590    // __len >= 2
3591    difference_type __len = _VSTD::distance(__first, __last) + 1;
3592    pair<value_type*, ptrdiff_t> __p(0, 0);
3593    unique_ptr<value_type, __return_temporary_buffer> __h;
3594    if (__len >= __alloc_limit)
3595    {
3596        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3597        __h.reset(__p.first);
3598    }
3599    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3600                             (__first, __last, __pred, __len, __p, bidirectional_iterator_tag());
3601}
3602
3603template <class _ForwardIterator, class _Predicate>
3604inline _LIBCPP_INLINE_VISIBILITY
3605_ForwardIterator
3606stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3607{
3608    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3609                             (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3610}
3611
3612// is_sorted_until
3613
3614template <class _ForwardIterator, class _Compare>
3615_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3616is_sorted_until(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3617{
3618    if (__first != __last)
3619    {
3620        _ForwardIterator __i = __first;
3621        while (++__i != __last)
3622        {
3623            if (__comp(*__i, *__first))
3624                return __i;
3625            __first = __i;
3626        }
3627    }
3628    return __last;
3629}
3630
3631template<class _ForwardIterator>
3632_LIBCPP_NODISCARD_EXT inline
3633_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3634_ForwardIterator
3635is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
3636{
3637    return _VSTD::is_sorted_until(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3638}
3639
3640// is_sorted
3641
3642template <class _ForwardIterator, class _Compare>
3643_LIBCPP_NODISCARD_EXT inline
3644_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3645bool
3646is_sorted(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3647{
3648    return _VSTD::is_sorted_until(__first, __last, __comp) == __last;
3649}
3650
3651template<class _ForwardIterator>
3652_LIBCPP_NODISCARD_EXT inline
3653_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3654bool
3655is_sorted(_ForwardIterator __first, _ForwardIterator __last)
3656{
3657    return _VSTD::is_sorted(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3658}
3659
3660// sort
3661
3662// stable, 2-3 compares, 0-2 swaps
3663
3664template <class _Compare, class _ForwardIterator>
3665unsigned
3666__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
3667{
3668    unsigned __r = 0;
3669    if (!__c(*__y, *__x))          // if x <= y
3670    {
3671        if (!__c(*__z, *__y))      // if y <= z
3672            return __r;            // x <= y && y <= z
3673                                   // x <= y && y > z
3674        swap(*__y, *__z);          // x <= z && y < z
3675        __r = 1;
3676        if (__c(*__y, *__x))       // if x > y
3677        {
3678            swap(*__x, *__y);      // x < y && y <= z
3679            __r = 2;
3680        }
3681        return __r;                // x <= y && y < z
3682    }
3683    if (__c(*__z, *__y))           // x > y, if y > z
3684    {
3685        swap(*__x, *__z);          // x < y && y < z
3686        __r = 1;
3687        return __r;
3688    }
3689    swap(*__x, *__y);              // x > y && y <= z
3690    __r = 1;                       // x < y && x <= z
3691    if (__c(*__z, *__y))           // if y > z
3692    {
3693        swap(*__y, *__z);          // x <= y && y < z
3694        __r = 2;
3695    }
3696    return __r;
3697}                                  // x <= y && y <= z
3698
3699// stable, 3-6 compares, 0-5 swaps
3700
3701template <class _Compare, class _ForwardIterator>
3702unsigned
3703__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3704            _ForwardIterator __x4, _Compare __c)
3705{
3706    unsigned __r = __sort3<_Compare>(__x1, __x2, __x3, __c);
3707    if (__c(*__x4, *__x3))
3708    {
3709        swap(*__x3, *__x4);
3710        ++__r;
3711        if (__c(*__x3, *__x2))
3712        {
3713            swap(*__x2, *__x3);
3714            ++__r;
3715            if (__c(*__x2, *__x1))
3716            {
3717                swap(*__x1, *__x2);
3718                ++__r;
3719            }
3720        }
3721    }
3722    return __r;
3723}
3724
3725// stable, 4-10 compares, 0-9 swaps
3726
3727template <class _Compare, class _ForwardIterator>
3728_LIBCPP_HIDDEN
3729unsigned
3730__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3731            _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
3732{
3733    unsigned __r = __sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
3734    if (__c(*__x5, *__x4))
3735    {
3736        swap(*__x4, *__x5);
3737        ++__r;
3738        if (__c(*__x4, *__x3))
3739        {
3740            swap(*__x3, *__x4);
3741            ++__r;
3742            if (__c(*__x3, *__x2))
3743            {
3744                swap(*__x2, *__x3);
3745                ++__r;
3746                if (__c(*__x2, *__x1))
3747                {
3748                    swap(*__x1, *__x2);
3749                    ++__r;
3750                }
3751            }
3752        }
3753    }
3754    return __r;
3755}
3756
3757// Assumes size > 0
3758template <class _Compare, class _BirdirectionalIterator>
3759void
3760__selection_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3761{
3762    _BirdirectionalIterator __lm1 = __last;
3763    for (--__lm1; __first != __lm1; ++__first)
3764    {
3765        _BirdirectionalIterator __i = _VSTD::min_element<_BirdirectionalIterator,
3766                                                        typename add_lvalue_reference<_Compare>::type>
3767                                                       (__first, __last, __comp);
3768        if (__i != __first)
3769            swap(*__first, *__i);
3770    }
3771}
3772
3773template <class _Compare, class _BirdirectionalIterator>
3774void
3775__insertion_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3776{
3777    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3778    if (__first != __last)
3779    {
3780        _BirdirectionalIterator __i = __first;
3781        for (++__i; __i != __last; ++__i)
3782        {
3783            _BirdirectionalIterator __j = __i;
3784            value_type __t(_VSTD::move(*__j));
3785            for (_BirdirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
3786                *__j = _VSTD::move(*__k);
3787            *__j = _VSTD::move(__t);
3788        }
3789    }
3790}
3791
3792template <class _Compare, class _RandomAccessIterator>
3793void
3794__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3795{
3796    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3797    _RandomAccessIterator __j = __first+2;
3798    __sort3<_Compare>(__first, __first+1, __j, __comp);
3799    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3800    {
3801        if (__comp(*__i, *__j))
3802        {
3803            value_type __t(_VSTD::move(*__i));
3804            _RandomAccessIterator __k = __j;
3805            __j = __i;
3806            do
3807            {
3808                *__j = _VSTD::move(*__k);
3809                __j = __k;
3810            } while (__j != __first && __comp(__t, *--__k));
3811            *__j = _VSTD::move(__t);
3812        }
3813        __j = __i;
3814    }
3815}
3816
3817template <class _Compare, class _RandomAccessIterator>
3818bool
3819__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3820{
3821    switch (__last - __first)
3822    {
3823    case 0:
3824    case 1:
3825        return true;
3826    case 2:
3827        if (__comp(*--__last, *__first))
3828            swap(*__first, *__last);
3829        return true;
3830    case 3:
3831        _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3832        return true;
3833    case 4:
3834        _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3835        return true;
3836    case 5:
3837        _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3838        return true;
3839    }
3840    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3841    _RandomAccessIterator __j = __first+2;
3842    __sort3<_Compare>(__first, __first+1, __j, __comp);
3843    const unsigned __limit = 8;
3844    unsigned __count = 0;
3845    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3846    {
3847        if (__comp(*__i, *__j))
3848        {
3849            value_type __t(_VSTD::move(*__i));
3850            _RandomAccessIterator __k = __j;
3851            __j = __i;
3852            do
3853            {
3854                *__j = _VSTD::move(*__k);
3855                __j = __k;
3856            } while (__j != __first && __comp(__t, *--__k));
3857            *__j = _VSTD::move(__t);
3858            if (++__count == __limit)
3859                return ++__i == __last;
3860        }
3861        __j = __i;
3862    }
3863    return true;
3864}
3865
3866template <class _Compare, class _BirdirectionalIterator>
3867void
3868__insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator __last1,
3869                      typename iterator_traits<_BirdirectionalIterator>::value_type* __first2, _Compare __comp)
3870{
3871    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3872    if (__first1 != __last1)
3873    {
3874        __destruct_n __d(0);
3875        unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
3876        value_type* __last2 = __first2;
3877        ::new(__last2) value_type(_VSTD::move(*__first1));
3878        __d.__incr((value_type*)0);
3879        for (++__last2; ++__first1 != __last1; ++__last2)
3880        {
3881            value_type* __j2 = __last2;
3882            value_type* __i2 = __j2;
3883            if (__comp(*__first1, *--__i2))
3884            {
3885                ::new(__j2) value_type(_VSTD::move(*__i2));
3886                __d.__incr((value_type*)0);
3887                for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
3888                    *__j2 = _VSTD::move(*__i2);
3889                *__j2 = _VSTD::move(*__first1);
3890            }
3891            else
3892            {
3893                ::new(__j2) value_type(_VSTD::move(*__first1));
3894                __d.__incr((value_type*)0);
3895            }
3896        }
3897        __h.release();
3898    }
3899}
3900
3901template <class _Compare, class _RandomAccessIterator>
3902void
3903__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3904{
3905    // _Compare is known to be a reference type
3906    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3907    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3908    const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
3909                                    is_trivially_copy_assignable<value_type>::value ? 30 : 6;
3910    while (true)
3911    {
3912    __restart:
3913        difference_type __len = __last - __first;
3914        switch (__len)
3915        {
3916        case 0:
3917        case 1:
3918            return;
3919        case 2:
3920            if (__comp(*--__last, *__first))
3921                swap(*__first, *__last);
3922            return;
3923        case 3:
3924            _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3925            return;
3926        case 4:
3927            _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3928            return;
3929        case 5:
3930            _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3931            return;
3932        }
3933        if (__len <= __limit)
3934        {
3935            _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
3936            return;
3937        }
3938        // __len > 5
3939        _RandomAccessIterator __m = __first;
3940        _RandomAccessIterator __lm1 = __last;
3941        --__lm1;
3942        unsigned __n_swaps;
3943        {
3944        difference_type __delta;
3945        if (__len >= 1000)
3946        {
3947            __delta = __len/2;
3948            __m += __delta;
3949            __delta /= 2;
3950            __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
3951        }
3952        else
3953        {
3954            __delta = __len/2;
3955            __m += __delta;
3956            __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
3957        }
3958        }
3959        // *__m is median
3960        // partition [__first, __m) < *__m and *__m <= [__m, __last)
3961        // (this inhibits tossing elements equivalent to __m around unnecessarily)
3962        _RandomAccessIterator __i = __first;
3963        _RandomAccessIterator __j = __lm1;
3964        // j points beyond range to be tested, *__m is known to be <= *__lm1
3965        // The search going up is known to be guarded but the search coming down isn't.
3966        // Prime the downward search with a guard.
3967        if (!__comp(*__i, *__m))  // if *__first == *__m
3968        {
3969            // *__first == *__m, *__first doesn't go in first part
3970            // manually guard downward moving __j against __i
3971            while (true)
3972            {
3973                if (__i == --__j)
3974                {
3975                    // *__first == *__m, *__m <= all other elements
3976                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
3977                    ++__i;  // __first + 1
3978                    __j = __last;
3979                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
3980                    {
3981                        while (true)
3982                        {
3983                            if (__i == __j)
3984                                return;  // [__first, __last) all equivalent elements
3985                            if (__comp(*__first, *__i))
3986                            {
3987                                swap(*__i, *__j);
3988                                ++__n_swaps;
3989                                ++__i;
3990                                break;
3991                            }
3992                            ++__i;
3993                        }
3994                    }
3995                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
3996                    if (__i == __j)
3997                        return;
3998                    while (true)
3999                    {
4000                        while (!__comp(*__first, *__i))
4001                            ++__i;
4002                        while (__comp(*__first, *--__j))
4003                            ;
4004                        if (__i >= __j)
4005                            break;
4006                        swap(*__i, *__j);
4007                        ++__n_swaps;
4008                        ++__i;
4009                    }
4010                    // [__first, __i) == *__first and *__first < [__i, __last)
4011                    // The first part is sorted, sort the secod part
4012                    // _VSTD::__sort<_Compare>(__i, __last, __comp);
4013                    __first = __i;
4014                    goto __restart;
4015                }
4016                if (__comp(*__j, *__m))
4017                {
4018                    swap(*__i, *__j);
4019                    ++__n_swaps;
4020                    break;  // found guard for downward moving __j, now use unguarded partition
4021                }
4022            }
4023        }
4024        // It is known that *__i < *__m
4025        ++__i;
4026        // j points beyond range to be tested, *__m is known to be <= *__lm1
4027        // if not yet partitioned...
4028        if (__i < __j)
4029        {
4030            // known that *(__i - 1) < *__m
4031            // known that __i <= __m
4032            while (true)
4033            {
4034                // __m still guards upward moving __i
4035                while (__comp(*__i, *__m))
4036                    ++__i;
4037                // It is now known that a guard exists for downward moving __j
4038                while (!__comp(*--__j, *__m))
4039                    ;
4040                if (__i > __j)
4041                    break;
4042                swap(*__i, *__j);
4043                ++__n_swaps;
4044                // It is known that __m != __j
4045                // If __m just moved, follow it
4046                if (__m == __i)
4047                    __m = __j;
4048                ++__i;
4049            }
4050        }
4051        // [__first, __i) < *__m and *__m <= [__i, __last)
4052        if (__i != __m && __comp(*__m, *__i))
4053        {
4054            swap(*__i, *__m);
4055            ++__n_swaps;
4056        }
4057        // [__first, __i) < *__i and *__i <= [__i+1, __last)
4058        // If we were given a perfect partition, see if insertion sort is quick...
4059        if (__n_swaps == 0)
4060        {
4061            bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
4062            if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
4063            {
4064                if (__fs)
4065                    return;
4066                __last = __i;
4067                continue;
4068            }
4069            else
4070            {
4071                if (__fs)
4072                {
4073                    __first = ++__i;
4074                    continue;
4075                }
4076            }
4077        }
4078        // sort smaller range with recursive call and larger with tail recursion elimination
4079        if (__i - __first < __last - __i)
4080        {
4081            _VSTD::__sort<_Compare>(__first, __i, __comp);
4082            // _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4083            __first = ++__i;
4084        }
4085        else
4086        {
4087            _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4088            // _VSTD::__sort<_Compare>(__first, __i, __comp);
4089            __last = __i;
4090        }
4091    }
4092}
4093
4094// This forwarder keeps the top call and the recursive calls using the same instantiation, forcing a reference _Compare
4095template <class _RandomAccessIterator, class _Compare>
4096inline _LIBCPP_INLINE_VISIBILITY
4097void
4098sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4099{
4100    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4101    _VSTD::__sort<_Comp_ref>(__first, __last, _Comp_ref(__comp));
4102}
4103
4104template <class _RandomAccessIterator>
4105inline _LIBCPP_INLINE_VISIBILITY
4106void
4107sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4108{
4109    _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4110}
4111
4112template <class _Tp>
4113inline _LIBCPP_INLINE_VISIBILITY
4114void
4115sort(_Tp** __first, _Tp** __last)
4116{
4117    _VSTD::sort((size_t*)__first, (size_t*)__last, __less<size_t>());
4118}
4119
4120template <class _Tp>
4121inline _LIBCPP_INLINE_VISIBILITY
4122void
4123sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last)
4124{
4125    _VSTD::sort(__first.base(), __last.base());
4126}
4127
4128template <class _Tp, class _Compare>
4129inline _LIBCPP_INLINE_VISIBILITY
4130void
4131sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last, _Compare __comp)
4132{
4133    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4134    _VSTD::sort<_Tp*, _Comp_ref>(__first.base(), __last.base(), __comp);
4135}
4136
4137_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
4138_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4139_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4140_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4141_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
4142_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4143_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
4144_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4145_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
4146_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4147_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4148_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
4149_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
4150_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
4151_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4152
4153_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
4154_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4155_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4156_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4157_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
4158_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4159_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
4160_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4161_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
4162_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4163_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4164_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
4165_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
4166_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
4167_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4168
4169_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
4170
4171// lower_bound
4172
4173template <class _Compare, class _ForwardIterator, class _Tp>
4174_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4175__lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4176{
4177    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4178    difference_type __len = _VSTD::distance(__first, __last);
4179    while (__len != 0)
4180    {
4181        difference_type __l2 = _VSTD::__half_positive(__len);
4182        _ForwardIterator __m = __first;
4183        _VSTD::advance(__m, __l2);
4184        if (__comp(*__m, __value_))
4185        {
4186            __first = ++__m;
4187            __len -= __l2 + 1;
4188        }
4189        else
4190            __len = __l2;
4191    }
4192    return __first;
4193}
4194
4195template <class _ForwardIterator, class _Tp, class _Compare>
4196_LIBCPP_NODISCARD_EXT inline
4197_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4198_ForwardIterator
4199lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4200{
4201    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4202    return __lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
4203}
4204
4205template <class _ForwardIterator, class _Tp>
4206_LIBCPP_NODISCARD_EXT inline
4207_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4208_ForwardIterator
4209lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4210{
4211    return _VSTD::lower_bound(__first, __last, __value_,
4212                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4213}
4214
4215// upper_bound
4216
4217template <class _Compare, class _ForwardIterator, class _Tp>
4218_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4219__upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4220{
4221    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4222    difference_type __len = _VSTD::distance(__first, __last);
4223    while (__len != 0)
4224    {
4225        difference_type __l2 = _VSTD::__half_positive(__len);
4226        _ForwardIterator __m = __first;
4227        _VSTD::advance(__m, __l2);
4228        if (__comp(__value_, *__m))
4229            __len = __l2;
4230        else
4231        {
4232            __first = ++__m;
4233            __len -= __l2 + 1;
4234        }
4235    }
4236    return __first;
4237}
4238
4239template <class _ForwardIterator, class _Tp, class _Compare>
4240_LIBCPP_NODISCARD_EXT inline
4241_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4242_ForwardIterator
4243upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4244{
4245    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4246    return __upper_bound<_Comp_ref>(__first, __last, __value_, __comp);
4247}
4248
4249template <class _ForwardIterator, class _Tp>
4250_LIBCPP_NODISCARD_EXT inline
4251_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4252_ForwardIterator
4253upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4254{
4255    return _VSTD::upper_bound(__first, __last, __value_,
4256                             __less<_Tp, typename iterator_traits<_ForwardIterator>::value_type>());
4257}
4258
4259// equal_range
4260
4261template <class _Compare, class _ForwardIterator, class _Tp>
4262_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
4263__equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4264{
4265    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4266    difference_type __len = _VSTD::distance(__first, __last);
4267    while (__len != 0)
4268    {
4269        difference_type __l2 = _VSTD::__half_positive(__len);
4270        _ForwardIterator __m = __first;
4271        _VSTD::advance(__m, __l2);
4272        if (__comp(*__m, __value_))
4273        {
4274            __first = ++__m;
4275            __len -= __l2 + 1;
4276        }
4277        else if (__comp(__value_, *__m))
4278        {
4279            __last = __m;
4280            __len = __l2;
4281        }
4282        else
4283        {
4284            _ForwardIterator __mp1 = __m;
4285            return pair<_ForwardIterator, _ForwardIterator>
4286                   (
4287                      __lower_bound<_Compare>(__first, __m, __value_, __comp),
4288                      __upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
4289                   );
4290        }
4291    }
4292    return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
4293}
4294
4295template <class _ForwardIterator, class _Tp, class _Compare>
4296_LIBCPP_NODISCARD_EXT inline
4297_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4298pair<_ForwardIterator, _ForwardIterator>
4299equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4300{
4301    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4302    return __equal_range<_Comp_ref>(__first, __last, __value_, __comp);
4303}
4304
4305template <class _ForwardIterator, class _Tp>
4306_LIBCPP_NODISCARD_EXT inline
4307_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4308pair<_ForwardIterator, _ForwardIterator>
4309equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4310{
4311    return _VSTD::equal_range(__first, __last, __value_,
4312                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4313}
4314
4315// binary_search
4316
4317template <class _Compare, class _ForwardIterator, class _Tp>
4318inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4319bool
4320__binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4321{
4322    __first = __lower_bound<_Compare>(__first, __last, __value_, __comp);
4323    return __first != __last && !__comp(__value_, *__first);
4324}
4325
4326template <class _ForwardIterator, class _Tp, class _Compare>
4327_LIBCPP_NODISCARD_EXT inline
4328_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4329bool
4330binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4331{
4332    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4333    return __binary_search<_Comp_ref>(__first, __last, __value_, __comp);
4334}
4335
4336template <class _ForwardIterator, class _Tp>
4337_LIBCPP_NODISCARD_EXT inline
4338_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4339bool
4340binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4341{
4342    return _VSTD::binary_search(__first, __last, __value_,
4343                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4344}
4345
4346// merge
4347
4348template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4349_OutputIterator
4350__merge(_InputIterator1 __first1, _InputIterator1 __last1,
4351        _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4352{
4353    for (; __first1 != __last1; ++__result)
4354    {
4355        if (__first2 == __last2)
4356            return _VSTD::copy(__first1, __last1, __result);
4357        if (__comp(*__first2, *__first1))
4358        {
4359            *__result = *__first2;
4360            ++__first2;
4361        }
4362        else
4363        {
4364            *__result = *__first1;
4365            ++__first1;
4366        }
4367    }
4368    return _VSTD::copy(__first2, __last2, __result);
4369}
4370
4371template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
4372inline _LIBCPP_INLINE_VISIBILITY
4373_OutputIterator
4374merge(_InputIterator1 __first1, _InputIterator1 __last1,
4375      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4376{
4377    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4378    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
4379}
4380
4381template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
4382inline _LIBCPP_INLINE_VISIBILITY
4383_OutputIterator
4384merge(_InputIterator1 __first1, _InputIterator1 __last1,
4385      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
4386{
4387    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
4388    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
4389    return merge(__first1, __last1, __first2, __last2, __result, __less<__v1, __v2>());
4390}
4391
4392// inplace_merge
4393
4394template <class _Compare, class _InputIterator1, class _InputIterator2,
4395          class _OutputIterator>
4396void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
4397                          _InputIterator2 __first2, _InputIterator2 __last2,
4398                          _OutputIterator __result, _Compare __comp)
4399{
4400    for (; __first1 != __last1; ++__result)
4401    {
4402        if (__first2 == __last2)
4403        {
4404            _VSTD::move(__first1, __last1, __result);
4405            return;
4406        }
4407
4408        if (__comp(*__first2, *__first1))
4409        {
4410            *__result = _VSTD::move(*__first2);
4411            ++__first2;
4412        }
4413        else
4414        {
4415            *__result = _VSTD::move(*__first1);
4416            ++__first1;
4417        }
4418    }
4419    // __first2 through __last2 are already in the right spot.
4420}
4421
4422template <class _Compare, class _BidirectionalIterator>
4423void
4424__buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4425                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
4426                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
4427                typename iterator_traits<_BidirectionalIterator>::value_type* __buff)
4428{
4429    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4430    __destruct_n __d(0);
4431    unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4432    if (__len1 <= __len2)
4433    {
4434        value_type* __p = __buff;
4435        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4436            ::new(__p) value_type(_VSTD::move(*__i));
4437        __half_inplace_merge(__buff, __p, __middle, __last, __first, __comp);
4438    }
4439    else
4440    {
4441        value_type* __p = __buff;
4442        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4443            ::new(__p) value_type(_VSTD::move(*__i));
4444        typedef reverse_iterator<_BidirectionalIterator> _RBi;
4445        typedef reverse_iterator<value_type*> _Rv;
4446        __half_inplace_merge(_Rv(__p), _Rv(__buff),
4447                             _RBi(__middle), _RBi(__first),
4448                             _RBi(__last), __invert<_Compare>(__comp));
4449    }
4450}
4451
4452template <class _Compare, class _BidirectionalIterator>
4453void
4454__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4455                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
4456                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
4457                typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
4458{
4459    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4460    while (true)
4461    {
4462        // if __middle == __last, we're done
4463        if (__len2 == 0)
4464            return;
4465        if (__len1 <= __buff_size || __len2 <= __buff_size)
4466            return __buffered_inplace_merge<_Compare>
4467                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
4468        // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
4469        for (; true; ++__first, (void) --__len1)
4470        {
4471            if (__len1 == 0)
4472                return;
4473            if (__comp(*__middle, *__first))
4474                break;
4475        }
4476        // __first < __middle < __last
4477        // *__first > *__middle
4478        // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
4479        //     all elements in:
4480        //         [__first, __m1)  <= [__middle, __m2)
4481        //         [__middle, __m2) <  [__m1, __middle)
4482        //         [__m1, __middle) <= [__m2, __last)
4483        //     and __m1 or __m2 is in the middle of its range
4484        _BidirectionalIterator __m1;  // "median" of [__first, __middle)
4485        _BidirectionalIterator __m2;  // "median" of [__middle, __last)
4486        difference_type __len11;      // distance(__first, __m1)
4487        difference_type __len21;      // distance(__middle, __m2)
4488        // binary search smaller range
4489        if (__len1 < __len2)
4490        {   // __len >= 1, __len2 >= 2
4491            __len21 = __len2 / 2;
4492            __m2 = __middle;
4493            _VSTD::advance(__m2, __len21);
4494            __m1 = __upper_bound<_Compare>(__first, __middle, *__m2, __comp);
4495            __len11 = _VSTD::distance(__first, __m1);
4496        }
4497        else
4498        {
4499            if (__len1 == 1)
4500            {   // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
4501                // It is known *__first > *__middle
4502                swap(*__first, *__middle);
4503                return;
4504            }
4505            // __len1 >= 2, __len2 >= 1
4506            __len11 = __len1 / 2;
4507            __m1 = __first;
4508            _VSTD::advance(__m1, __len11);
4509            __m2 = __lower_bound<_Compare>(__middle, __last, *__m1, __comp);
4510            __len21 = _VSTD::distance(__middle, __m2);
4511        }
4512        difference_type __len12 = __len1 - __len11;  // distance(__m1, __middle)
4513        difference_type __len22 = __len2 - __len21;  // distance(__m2, __last)
4514        // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
4515        // swap middle two partitions
4516        __middle = _VSTD::rotate(__m1, __middle, __m2);
4517        // __len12 and __len21 now have swapped meanings
4518        // merge smaller range with recurisve call and larger with tail recursion elimination
4519        if (__len11 + __len21 < __len12 + __len22)
4520        {
4521            __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4522//          __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4523            __first = __middle;
4524            __middle = __m2;
4525            __len1 = __len12;
4526            __len2 = __len22;
4527        }
4528        else
4529        {
4530            __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4531//          __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4532            __last = __middle;
4533            __middle = __m1;
4534            __len1 = __len11;
4535            __len2 = __len21;
4536        }
4537    }
4538}
4539
4540template <class _BidirectionalIterator, class _Compare>
4541inline _LIBCPP_INLINE_VISIBILITY
4542void
4543inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4544              _Compare __comp)
4545{
4546    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4547    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4548    difference_type __len1 = _VSTD::distance(__first, __middle);
4549    difference_type __len2 = _VSTD::distance(__middle, __last);
4550    difference_type __buf_size = _VSTD::min(__len1, __len2);
4551    pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
4552    unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
4553    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4554    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
4555                                            __buf.first, __buf.second);
4556}
4557
4558template <class _BidirectionalIterator>
4559inline _LIBCPP_INLINE_VISIBILITY
4560void
4561inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
4562{
4563    _VSTD::inplace_merge(__first, __middle, __last,
4564                        __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
4565}
4566
4567// stable_sort
4568
4569template <class _Compare, class _InputIterator1, class _InputIterator2>
4570void
4571__merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
4572        _InputIterator2 __first2, _InputIterator2 __last2,
4573        typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
4574{
4575    typedef typename iterator_traits<_InputIterator1>::value_type value_type;
4576    __destruct_n __d(0);
4577    unique_ptr<value_type, __destruct_n&> __h(__result, __d);
4578    for (; true; ++__result)
4579    {
4580        if (__first1 == __last1)
4581        {
4582            for (; __first2 != __last2; ++__first2, ++__result, __d.__incr((value_type*)0))
4583                ::new (__result) value_type(_VSTD::move(*__first2));
4584            __h.release();
4585            return;
4586        }
4587        if (__first2 == __last2)
4588        {
4589            for (; __first1 != __last1; ++__first1, ++__result, __d.__incr((value_type*)0))
4590                ::new (__result) value_type(_VSTD::move(*__first1));
4591            __h.release();
4592            return;
4593        }
4594        if (__comp(*__first2, *__first1))
4595        {
4596            ::new (__result) value_type(_VSTD::move(*__first2));
4597            __d.__incr((value_type*)0);
4598            ++__first2;
4599        }
4600        else
4601        {
4602            ::new (__result) value_type(_VSTD::move(*__first1));
4603            __d.__incr((value_type*)0);
4604            ++__first1;
4605        }
4606    }
4607}
4608
4609template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4610void
4611__merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
4612        _InputIterator2 __first2, _InputIterator2 __last2,
4613        _OutputIterator __result, _Compare __comp)
4614{
4615    for (; __first1 != __last1; ++__result)
4616    {
4617        if (__first2 == __last2)
4618        {
4619            for (; __first1 != __last1; ++__first1, ++__result)
4620                *__result = _VSTD::move(*__first1);
4621            return;
4622        }
4623        if (__comp(*__first2, *__first1))
4624        {
4625            *__result = _VSTD::move(*__first2);
4626            ++__first2;
4627        }
4628        else
4629        {
4630            *__result = _VSTD::move(*__first1);
4631            ++__first1;
4632        }
4633    }
4634    for (; __first2 != __last2; ++__first2, ++__result)
4635        *__result = _VSTD::move(*__first2);
4636}
4637
4638template <class _Compare, class _RandomAccessIterator>
4639void
4640__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4641              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4642              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
4643
4644template <class _Compare, class _RandomAccessIterator>
4645void
4646__stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
4647                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4648                   typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
4649{
4650    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4651    switch (__len)
4652    {
4653    case 0:
4654        return;
4655    case 1:
4656        ::new(__first2) value_type(_VSTD::move(*__first1));
4657        return;
4658    case 2:
4659        __destruct_n __d(0);
4660        unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
4661        if (__comp(*--__last1, *__first1))
4662        {
4663            ::new(__first2) value_type(_VSTD::move(*__last1));
4664            __d.__incr((value_type*)0);
4665            ++__first2;
4666            ::new(__first2) value_type(_VSTD::move(*__first1));
4667        }
4668        else
4669        {
4670            ::new(__first2) value_type(_VSTD::move(*__first1));
4671            __d.__incr((value_type*)0);
4672            ++__first2;
4673            ::new(__first2) value_type(_VSTD::move(*__last1));
4674        }
4675        __h2.release();
4676        return;
4677    }
4678    if (__len <= 8)
4679    {
4680        __insertion_sort_move<_Compare>(__first1, __last1, __first2, __comp);
4681        return;
4682    }
4683    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4684    _RandomAccessIterator __m = __first1 + __l2;
4685    __stable_sort<_Compare>(__first1, __m, __comp, __l2, __first2, __l2);
4686    __stable_sort<_Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
4687    __merge_move_construct<_Compare>(__first1, __m, __m, __last1, __first2, __comp);
4688}
4689
4690template <class _Tp>
4691struct __stable_sort_switch
4692{
4693    static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
4694};
4695
4696template <class _Compare, class _RandomAccessIterator>
4697void
4698__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4699              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4700              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
4701{
4702    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4703    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4704    switch (__len)
4705    {
4706    case 0:
4707    case 1:
4708        return;
4709    case 2:
4710        if (__comp(*--__last, *__first))
4711            swap(*__first, *__last);
4712        return;
4713    }
4714    if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4715    {
4716        __insertion_sort<_Compare>(__first, __last, __comp);
4717        return;
4718    }
4719    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4720    _RandomAccessIterator __m = __first + __l2;
4721    if (__len <= __buff_size)
4722    {
4723        __destruct_n __d(0);
4724        unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4725        __stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
4726        __d.__set(__l2, (value_type*)0);
4727        __stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
4728        __d.__set(__len, (value_type*)0);
4729        __merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
4730//         __merge<_Compare>(move_iterator<value_type*>(__buff),
4731//                           move_iterator<value_type*>(__buff + __l2),
4732//                           move_iterator<_RandomAccessIterator>(__buff + __l2),
4733//                           move_iterator<_RandomAccessIterator>(__buff + __len),
4734//                           __first, __comp);
4735        return;
4736    }
4737    __stable_sort<_Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
4738    __stable_sort<_Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
4739    __inplace_merge<_Compare>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
4740}
4741
4742template <class _RandomAccessIterator, class _Compare>
4743inline _LIBCPP_INLINE_VISIBILITY
4744void
4745stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4746{
4747    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4748    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4749    difference_type __len = __last - __first;
4750    pair<value_type*, ptrdiff_t> __buf(0, 0);
4751    unique_ptr<value_type, __return_temporary_buffer> __h;
4752    if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4753    {
4754        __buf = _VSTD::get_temporary_buffer<value_type>(__len);
4755        __h.reset(__buf.first);
4756    }
4757    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4758    __stable_sort<_Comp_ref>(__first, __last, __comp, __len, __buf.first, __buf.second);
4759}
4760
4761template <class _RandomAccessIterator>
4762inline _LIBCPP_INLINE_VISIBILITY
4763void
4764stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4765{
4766    _VSTD::stable_sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4767}
4768
4769// is_heap_until
4770
4771template <class _RandomAccessIterator, class _Compare>
4772_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
4773is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4774{
4775    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4776    difference_type __len = __last - __first;
4777    difference_type __p = 0;
4778    difference_type __c = 1;
4779    _RandomAccessIterator __pp = __first;
4780    while (__c < __len)
4781    {
4782        _RandomAccessIterator __cp = __first + __c;
4783        if (__comp(*__pp, *__cp))
4784            return __cp;
4785        ++__c;
4786        ++__cp;
4787        if (__c == __len)
4788            return __last;
4789        if (__comp(*__pp, *__cp))
4790            return __cp;
4791        ++__p;
4792        ++__pp;
4793        __c = 2 * __p + 1;
4794    }
4795    return __last;
4796}
4797
4798template<class _RandomAccessIterator>
4799_LIBCPP_NODISCARD_EXT inline
4800_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4801_RandomAccessIterator
4802is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
4803{
4804    return _VSTD::is_heap_until(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4805}
4806
4807// is_heap
4808
4809template <class _RandomAccessIterator, class _Compare>
4810_LIBCPP_NODISCARD_EXT inline
4811_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4812bool
4813is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4814{
4815    return _VSTD::is_heap_until(__first, __last, __comp) == __last;
4816}
4817
4818template<class _RandomAccessIterator>
4819_LIBCPP_NODISCARD_EXT inline
4820_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4821bool
4822is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4823{
4824    return _VSTD::is_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4825}
4826
4827// push_heap
4828
4829template <class _Compare, class _RandomAccessIterator>
4830void
4831__sift_up(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4832          typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4833{
4834    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4835    if (__len > 1)
4836    {
4837        __len = (__len - 2) / 2;
4838        _RandomAccessIterator __ptr = __first + __len;
4839        if (__comp(*__ptr, *--__last))
4840        {
4841            value_type __t(_VSTD::move(*__last));
4842            do
4843            {
4844                *__last = _VSTD::move(*__ptr);
4845                __last = __ptr;
4846                if (__len == 0)
4847                    break;
4848                __len = (__len - 1) / 2;
4849                __ptr = __first + __len;
4850            } while (__comp(*__ptr, __t));
4851            *__last = _VSTD::move(__t);
4852        }
4853    }
4854}
4855
4856template <class _RandomAccessIterator, class _Compare>
4857inline _LIBCPP_INLINE_VISIBILITY
4858void
4859push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4860{
4861    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4862    __sift_up<_Comp_ref>(__first, __last, __comp, __last - __first);
4863}
4864
4865template <class _RandomAccessIterator>
4866inline _LIBCPP_INLINE_VISIBILITY
4867void
4868push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4869{
4870    _VSTD::push_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4871}
4872
4873// pop_heap
4874
4875template <class _Compare, class _RandomAccessIterator>
4876void
4877__sift_down(_RandomAccessIterator __first, _RandomAccessIterator /*__last*/,
4878            _Compare __comp,
4879            typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4880            _RandomAccessIterator __start)
4881{
4882    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4883    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4884    // left-child of __start is at 2 * __start + 1
4885    // right-child of __start is at 2 * __start + 2
4886    difference_type __child = __start - __first;
4887
4888    if (__len < 2 || (__len - 2) / 2 < __child)
4889        return;
4890
4891    __child = 2 * __child + 1;
4892    _RandomAccessIterator __child_i = __first + __child;
4893
4894    if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4895        // right-child exists and is greater than left-child
4896        ++__child_i;
4897        ++__child;
4898    }
4899
4900    // check if we are in heap-order
4901    if (__comp(*__child_i, *__start))
4902        // we are, __start is larger than it's largest child
4903        return;
4904
4905    value_type __top(_VSTD::move(*__start));
4906    do
4907    {
4908        // we are not in heap-order, swap the parent with it's largest child
4909        *__start = _VSTD::move(*__child_i);
4910        __start = __child_i;
4911
4912        if ((__len - 2) / 2 < __child)
4913            break;
4914
4915        // recompute the child based off of the updated parent
4916        __child = 2 * __child + 1;
4917        __child_i = __first + __child;
4918
4919        if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4920            // right-child exists and is greater than left-child
4921            ++__child_i;
4922            ++__child;
4923        }
4924
4925        // check if we are in heap-order
4926    } while (!__comp(*__child_i, __top));
4927    *__start = _VSTD::move(__top);
4928}
4929
4930template <class _Compare, class _RandomAccessIterator>
4931inline _LIBCPP_INLINE_VISIBILITY
4932void
4933__pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4934           typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4935{
4936    if (__len > 1)
4937    {
4938        swap(*__first, *--__last);
4939        __sift_down<_Compare>(__first, __last, __comp, __len - 1, __first);
4940    }
4941}
4942
4943template <class _RandomAccessIterator, class _Compare>
4944inline _LIBCPP_INLINE_VISIBILITY
4945void
4946pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4947{
4948    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4949    __pop_heap<_Comp_ref>(__first, __last, __comp, __last - __first);
4950}
4951
4952template <class _RandomAccessIterator>
4953inline _LIBCPP_INLINE_VISIBILITY
4954void
4955pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4956{
4957    _VSTD::pop_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4958}
4959
4960// make_heap
4961
4962template <class _Compare, class _RandomAccessIterator>
4963void
4964__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4965{
4966    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4967    difference_type __n = __last - __first;
4968    if (__n > 1)
4969    {
4970        // start from the first parent, there is no need to consider children
4971        for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start)
4972        {
4973            __sift_down<_Compare>(__first, __last, __comp, __n, __first + __start);
4974        }
4975    }
4976}
4977
4978template <class _RandomAccessIterator, class _Compare>
4979inline _LIBCPP_INLINE_VISIBILITY
4980void
4981make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4982{
4983    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4984    __make_heap<_Comp_ref>(__first, __last, __comp);
4985}
4986
4987template <class _RandomAccessIterator>
4988inline _LIBCPP_INLINE_VISIBILITY
4989void
4990make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4991{
4992    _VSTD::make_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4993}
4994
4995// sort_heap
4996
4997template <class _Compare, class _RandomAccessIterator>
4998void
4999__sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5000{
5001    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5002    for (difference_type __n = __last - __first; __n > 1; --__last, --__n)
5003        __pop_heap<_Compare>(__first, __last, __comp, __n);
5004}
5005
5006template <class _RandomAccessIterator, class _Compare>
5007inline _LIBCPP_INLINE_VISIBILITY
5008void
5009sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5010{
5011    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5012    __sort_heap<_Comp_ref>(__first, __last, __comp);
5013}
5014
5015template <class _RandomAccessIterator>
5016inline _LIBCPP_INLINE_VISIBILITY
5017void
5018sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
5019{
5020    _VSTD::sort_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5021}
5022
5023// partial_sort
5024
5025template <class _Compare, class _RandomAccessIterator>
5026void
5027__partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5028             _Compare __comp)
5029{
5030    __make_heap<_Compare>(__first, __middle, __comp);
5031    typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
5032    for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
5033    {
5034        if (__comp(*__i, *__first))
5035        {
5036            swap(*__i, *__first);
5037            __sift_down<_Compare>(__first, __middle, __comp, __len, __first);
5038        }
5039    }
5040    __sort_heap<_Compare>(__first, __middle, __comp);
5041}
5042
5043template <class _RandomAccessIterator, class _Compare>
5044inline _LIBCPP_INLINE_VISIBILITY
5045void
5046partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5047             _Compare __comp)
5048{
5049    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5050    __partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
5051}
5052
5053template <class _RandomAccessIterator>
5054inline _LIBCPP_INLINE_VISIBILITY
5055void
5056partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
5057{
5058    _VSTD::partial_sort(__first, __middle, __last,
5059                       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5060}
5061
5062// partial_sort_copy
5063
5064template <class _Compare, class _InputIterator, class _RandomAccessIterator>
5065_RandomAccessIterator
5066__partial_sort_copy(_InputIterator __first, _InputIterator __last,
5067                    _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5068{
5069    _RandomAccessIterator __r = __result_first;
5070    if (__r != __result_last)
5071    {
5072        for (; __first != __last && __r != __result_last; (void) ++__first, ++__r)
5073            *__r = *__first;
5074        __make_heap<_Compare>(__result_first, __r, __comp);
5075        typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
5076        for (; __first != __last; ++__first)
5077            if (__comp(*__first, *__result_first))
5078            {
5079                *__result_first = *__first;
5080                __sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
5081            }
5082        __sort_heap<_Compare>(__result_first, __r, __comp);
5083    }
5084    return __r;
5085}
5086
5087template <class _InputIterator, class _RandomAccessIterator, class _Compare>
5088inline _LIBCPP_INLINE_VISIBILITY
5089_RandomAccessIterator
5090partial_sort_copy(_InputIterator __first, _InputIterator __last,
5091                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5092{
5093    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5094    return __partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
5095}
5096
5097template <class _InputIterator, class _RandomAccessIterator>
5098inline _LIBCPP_INLINE_VISIBILITY
5099_RandomAccessIterator
5100partial_sort_copy(_InputIterator __first, _InputIterator __last,
5101                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
5102{
5103    return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
5104                                   __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5105}
5106
5107// nth_element
5108
5109template <class _Compare, class _RandomAccessIterator>
5110void
5111__nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5112{
5113    // _Compare is known to be a reference type
5114    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5115    const difference_type __limit = 7;
5116    while (true)
5117    {
5118    __restart:
5119        if (__nth == __last)
5120            return;
5121        difference_type __len = __last - __first;
5122        switch (__len)
5123        {
5124        case 0:
5125        case 1:
5126            return;
5127        case 2:
5128            if (__comp(*--__last, *__first))
5129                swap(*__first, *__last);
5130            return;
5131        case 3:
5132            {
5133            _RandomAccessIterator __m = __first;
5134            _VSTD::__sort3<_Compare>(__first, ++__m, --__last, __comp);
5135            return;
5136            }
5137        }
5138        if (__len <= __limit)
5139        {
5140            __selection_sort<_Compare>(__first, __last, __comp);
5141            return;
5142        }
5143        // __len > __limit >= 3
5144        _RandomAccessIterator __m = __first + __len/2;
5145        _RandomAccessIterator __lm1 = __last;
5146        unsigned __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, --__lm1, __comp);
5147        // *__m is median
5148        // partition [__first, __m) < *__m and *__m <= [__m, __last)
5149        // (this inhibits tossing elements equivalent to __m around unnecessarily)
5150        _RandomAccessIterator __i = __first;
5151        _RandomAccessIterator __j = __lm1;
5152        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5153        // The search going up is known to be guarded but the search coming down isn't.
5154        // Prime the downward search with a guard.
5155        if (!__comp(*__i, *__m))  // if *__first == *__m
5156        {
5157            // *__first == *__m, *__first doesn't go in first part
5158            // manually guard downward moving __j against __i
5159            while (true)
5160            {
5161                if (__i == --__j)
5162                {
5163                    // *__first == *__m, *__m <= all other elements
5164                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
5165                    ++__i;  // __first + 1
5166                    __j = __last;
5167                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
5168                    {
5169                        while (true)
5170                        {
5171                            if (__i == __j)
5172                                return;  // [__first, __last) all equivalent elements
5173                            if (__comp(*__first, *__i))
5174                            {
5175                                swap(*__i, *__j);
5176                                ++__n_swaps;
5177                                ++__i;
5178                                break;
5179                            }
5180                            ++__i;
5181                        }
5182                    }
5183                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
5184                    if (__i == __j)
5185                        return;
5186                    while (true)
5187                    {
5188                        while (!__comp(*__first, *__i))
5189                            ++__i;
5190                        while (__comp(*__first, *--__j))
5191                            ;
5192                        if (__i >= __j)
5193                            break;
5194                        swap(*__i, *__j);
5195                        ++__n_swaps;
5196                        ++__i;
5197                    }
5198                    // [__first, __i) == *__first and *__first < [__i, __last)
5199                    // The first part is sorted,
5200                    if (__nth < __i)
5201                        return;
5202                    // __nth_element the secod part
5203                    // __nth_element<_Compare>(__i, __nth, __last, __comp);
5204                    __first = __i;
5205                    goto __restart;
5206                }
5207                if (__comp(*__j, *__m))
5208                {
5209                    swap(*__i, *__j);
5210                    ++__n_swaps;
5211                    break;  // found guard for downward moving __j, now use unguarded partition
5212                }
5213            }
5214        }
5215        ++__i;
5216        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5217        // if not yet partitioned...
5218        if (__i < __j)
5219        {
5220            // known that *(__i - 1) < *__m
5221            while (true)
5222            {
5223                // __m still guards upward moving __i
5224                while (__comp(*__i, *__m))
5225                    ++__i;
5226                // It is now known that a guard exists for downward moving __j
5227                while (!__comp(*--__j, *__m))
5228                    ;
5229                if (__i >= __j)
5230                    break;
5231                swap(*__i, *__j);
5232                ++__n_swaps;
5233                // It is known that __m != __j
5234                // If __m just moved, follow it
5235                if (__m == __i)
5236                    __m = __j;
5237                ++__i;
5238            }
5239        }
5240        // [__first, __i) < *__m and *__m <= [__i, __last)
5241        if (__i != __m && __comp(*__m, *__i))
5242        {
5243            swap(*__i, *__m);
5244            ++__n_swaps;
5245        }
5246        // [__first, __i) < *__i and *__i <= [__i+1, __last)
5247        if (__nth == __i)
5248            return;
5249        if (__n_swaps == 0)
5250        {
5251            // We were given a perfectly partitioned sequence.  Coincidence?
5252            if (__nth < __i)
5253            {
5254                // Check for [__first, __i) already sorted
5255                __j = __m = __first;
5256                while (++__j != __i)
5257                {
5258                    if (__comp(*__j, *__m))
5259                        // not yet sorted, so sort
5260                        goto not_sorted;
5261                    __m = __j;
5262                }
5263                // [__first, __i) sorted
5264                return;
5265            }
5266            else
5267            {
5268                // Check for [__i, __last) already sorted
5269                __j = __m = __i;
5270                while (++__j != __last)
5271                {
5272                    if (__comp(*__j, *__m))
5273                        // not yet sorted, so sort
5274                        goto not_sorted;
5275                    __m = __j;
5276                }
5277                // [__i, __last) sorted
5278                return;
5279            }
5280        }
5281not_sorted:
5282        // __nth_element on range containing __nth
5283        if (__nth < __i)
5284        {
5285            // __nth_element<_Compare>(__first, __nth, __i, __comp);
5286            __last = __i;
5287        }
5288        else
5289        {
5290            // __nth_element<_Compare>(__i+1, __nth, __last, __comp);
5291            __first = ++__i;
5292        }
5293    }
5294}
5295
5296template <class _RandomAccessIterator, class _Compare>
5297inline _LIBCPP_INLINE_VISIBILITY
5298void
5299nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5300{
5301    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5302    __nth_element<_Comp_ref>(__first, __nth, __last, __comp);
5303}
5304
5305template <class _RandomAccessIterator>
5306inline _LIBCPP_INLINE_VISIBILITY
5307void
5308nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
5309{
5310    _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5311}
5312
5313// includes
5314
5315template <class _Compare, class _InputIterator1, class _InputIterator2>
5316_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
5317__includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5318           _Compare __comp)
5319{
5320    for (; __first2 != __last2; ++__first1)
5321    {
5322        if (__first1 == __last1 || __comp(*__first2, *__first1))
5323            return false;
5324        if (!__comp(*__first1, *__first2))
5325            ++__first2;
5326    }
5327    return true;
5328}
5329
5330template <class _InputIterator1, class _InputIterator2, class _Compare>
5331_LIBCPP_NODISCARD_EXT inline
5332_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5333bool
5334includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5335         _Compare __comp)
5336{
5337    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5338    return __includes<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5339}
5340
5341template <class _InputIterator1, class _InputIterator2>
5342_LIBCPP_NODISCARD_EXT inline
5343_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5344bool
5345includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
5346{
5347    return _VSTD::includes(__first1, __last1, __first2, __last2,
5348                          __less<typename iterator_traits<_InputIterator1>::value_type,
5349                                 typename iterator_traits<_InputIterator2>::value_type>());
5350}
5351
5352// set_union
5353
5354template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5355_OutputIterator
5356__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5357            _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5358{
5359    for (; __first1 != __last1; ++__result)
5360    {
5361        if (__first2 == __last2)
5362            return _VSTD::copy(__first1, __last1, __result);
5363        if (__comp(*__first2, *__first1))
5364        {
5365            *__result = *__first2;
5366            ++__first2;
5367        }
5368        else
5369        {
5370            if (!__comp(*__first1, *__first2))
5371                ++__first2;
5372            *__result = *__first1;
5373            ++__first1;
5374        }
5375    }
5376    return _VSTD::copy(__first2, __last2, __result);
5377}
5378
5379template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5380inline _LIBCPP_INLINE_VISIBILITY
5381_OutputIterator
5382set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5383          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5384{
5385    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5386    return __set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5387}
5388
5389template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5390inline _LIBCPP_INLINE_VISIBILITY
5391_OutputIterator
5392set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5393          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5394{
5395    return _VSTD::set_union(__first1, __last1, __first2, __last2, __result,
5396                          __less<typename iterator_traits<_InputIterator1>::value_type,
5397                                 typename iterator_traits<_InputIterator2>::value_type>());
5398}
5399
5400// set_intersection
5401
5402template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5403_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
5404__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5405                   _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5406{
5407    while (__first1 != __last1 && __first2 != __last2)
5408    {
5409        if (__comp(*__first1, *__first2))
5410            ++__first1;
5411        else
5412        {
5413            if (!__comp(*__first2, *__first1))
5414            {
5415                *__result = *__first1;
5416                ++__result;
5417                ++__first1;
5418            }
5419            ++__first2;
5420        }
5421    }
5422    return __result;
5423}
5424
5425template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5426inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5427_OutputIterator
5428set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5429                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5430{
5431    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5432    return __set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5433}
5434
5435template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5436inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5437_OutputIterator
5438set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5439                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5440{
5441    return _VSTD::set_intersection(__first1, __last1, __first2, __last2, __result,
5442                                  __less<typename iterator_traits<_InputIterator1>::value_type,
5443                                         typename iterator_traits<_InputIterator2>::value_type>());
5444}
5445
5446// set_difference
5447
5448template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5449_OutputIterator
5450__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5451                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5452{
5453    while (__first1 != __last1)
5454    {
5455        if (__first2 == __last2)
5456            return _VSTD::copy(__first1, __last1, __result);
5457        if (__comp(*__first1, *__first2))
5458        {
5459            *__result = *__first1;
5460            ++__result;
5461            ++__first1;
5462        }
5463        else
5464        {
5465            if (!__comp(*__first2, *__first1))
5466                ++__first1;
5467            ++__first2;
5468        }
5469    }
5470    return __result;
5471}
5472
5473template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5474inline _LIBCPP_INLINE_VISIBILITY
5475_OutputIterator
5476set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5477               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5478{
5479    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5480    return __set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5481}
5482
5483template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5484inline _LIBCPP_INLINE_VISIBILITY
5485_OutputIterator
5486set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5487               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5488{
5489    return _VSTD::set_difference(__first1, __last1, __first2, __last2, __result,
5490                                __less<typename iterator_traits<_InputIterator1>::value_type,
5491                                       typename iterator_traits<_InputIterator2>::value_type>());
5492}
5493
5494// set_symmetric_difference
5495
5496template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5497_OutputIterator
5498__set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5499                           _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5500{
5501    while (__first1 != __last1)
5502    {
5503        if (__first2 == __last2)
5504            return _VSTD::copy(__first1, __last1, __result);
5505        if (__comp(*__first1, *__first2))
5506        {
5507            *__result = *__first1;
5508            ++__result;
5509            ++__first1;
5510        }
5511        else
5512        {
5513            if (__comp(*__first2, *__first1))
5514            {
5515                *__result = *__first2;
5516                ++__result;
5517            }
5518            else
5519                ++__first1;
5520            ++__first2;
5521        }
5522    }
5523    return _VSTD::copy(__first2, __last2, __result);
5524}
5525
5526template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5527inline _LIBCPP_INLINE_VISIBILITY
5528_OutputIterator
5529set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5530                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5531{
5532    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5533    return __set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5534}
5535
5536template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5537inline _LIBCPP_INLINE_VISIBILITY
5538_OutputIterator
5539set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5540                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5541{
5542    return _VSTD::set_symmetric_difference(__first1, __last1, __first2, __last2, __result,
5543                                          __less<typename iterator_traits<_InputIterator1>::value_type,
5544                                                 typename iterator_traits<_InputIterator2>::value_type>());
5545}
5546
5547// lexicographical_compare
5548
5549template <class _Compare, class _InputIterator1, class _InputIterator2>
5550_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
5551__lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5552                          _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5553{
5554    for (; __first2 != __last2; ++__first1, (void) ++__first2)
5555    {
5556        if (__first1 == __last1 || __comp(*__first1, *__first2))
5557            return true;
5558        if (__comp(*__first2, *__first1))
5559            return false;
5560    }
5561    return false;
5562}
5563
5564template <class _InputIterator1, class _InputIterator2, class _Compare>
5565_LIBCPP_NODISCARD_EXT inline
5566_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5567bool
5568lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5569                        _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5570{
5571    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5572    return __lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5573}
5574
5575template <class _InputIterator1, class _InputIterator2>
5576_LIBCPP_NODISCARD_EXT inline
5577_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5578bool
5579lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5580                        _InputIterator2 __first2, _InputIterator2 __last2)
5581{
5582    return _VSTD::lexicographical_compare(__first1, __last1, __first2, __last2,
5583                                         __less<typename iterator_traits<_InputIterator1>::value_type,
5584                                                typename iterator_traits<_InputIterator2>::value_type>());
5585}
5586
5587// next_permutation
5588
5589template <class _Compare, class _BidirectionalIterator>
5590bool
5591__next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5592{
5593    _BidirectionalIterator __i = __last;
5594    if (__first == __last || __first == --__i)
5595        return false;
5596    while (true)
5597    {
5598        _BidirectionalIterator __ip1 = __i;
5599        if (__comp(*--__i, *__ip1))
5600        {
5601            _BidirectionalIterator __j = __last;
5602            while (!__comp(*__i, *--__j))
5603                ;
5604            swap(*__i, *__j);
5605            _VSTD::reverse(__ip1, __last);
5606            return true;
5607        }
5608        if (__i == __first)
5609        {
5610            _VSTD::reverse(__first, __last);
5611            return false;
5612        }
5613    }
5614}
5615
5616template <class _BidirectionalIterator, class _Compare>
5617inline _LIBCPP_INLINE_VISIBILITY
5618bool
5619next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5620{
5621    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5622    return __next_permutation<_Comp_ref>(__first, __last, __comp);
5623}
5624
5625template <class _BidirectionalIterator>
5626inline _LIBCPP_INLINE_VISIBILITY
5627bool
5628next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5629{
5630    return _VSTD::next_permutation(__first, __last,
5631                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5632}
5633
5634// prev_permutation
5635
5636template <class _Compare, class _BidirectionalIterator>
5637bool
5638__prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5639{
5640    _BidirectionalIterator __i = __last;
5641    if (__first == __last || __first == --__i)
5642        return false;
5643    while (true)
5644    {
5645        _BidirectionalIterator __ip1 = __i;
5646        if (__comp(*__ip1, *--__i))
5647        {
5648            _BidirectionalIterator __j = __last;
5649            while (!__comp(*--__j, *__i))
5650                ;
5651            swap(*__i, *__j);
5652            _VSTD::reverse(__ip1, __last);
5653            return true;
5654        }
5655        if (__i == __first)
5656        {
5657            _VSTD::reverse(__first, __last);
5658            return false;
5659        }
5660    }
5661}
5662
5663template <class _BidirectionalIterator, class _Compare>
5664inline _LIBCPP_INLINE_VISIBILITY
5665bool
5666prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5667{
5668    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5669    return __prev_permutation<_Comp_ref>(__first, __last, __comp);
5670}
5671
5672template <class _BidirectionalIterator>
5673inline _LIBCPP_INLINE_VISIBILITY
5674bool
5675prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5676{
5677    return _VSTD::prev_permutation(__first, __last,
5678                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5679}
5680
5681_LIBCPP_END_NAMESPACE_STD
5682
5683_LIBCPP_POP_MACROS
5684
5685#endif  // _LIBCPP_ALGORITHM
5686