1// -*- C++ -*-
2//===-------------------------- algorithm ---------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_ALGORITHM
12#define _LIBCPP_ALGORITHM
13
14/*
15    algorithm synopsis
16
17#include <initializer_list>
18
19namespace std
20{
21
22template <class InputIterator, class Predicate>
23    constexpr bool     // constexpr in C++20
24    all_of(InputIterator first, InputIterator last, Predicate pred);
25
26template <class InputIterator, class Predicate>
27    constexpr bool     // constexpr in C++20
28    any_of(InputIterator first, InputIterator last, Predicate pred);
29
30template <class InputIterator, class Predicate>
31    constexpr bool     // constexpr in C++20
32    none_of(InputIterator first, InputIterator last, Predicate pred);
33
34template <class InputIterator, class Function>
35    Function
36    for_each(InputIterator first, InputIterator last, Function f);
37
38template<class InputIterator, class Size, class Function>
39    InputIterator 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    ForwardIterator
239    remove(ForwardIterator first, ForwardIterator last, const T& value);
240
241template <class ForwardIterator, class Predicate>
242    ForwardIterator
243    remove_if(ForwardIterator first, ForwardIterator last, Predicate pred);
244
245template <class InputIterator, class OutputIterator, class T>
246    OutputIterator
247    remove_copy(InputIterator first, InputIterator last, OutputIterator result, const T& value);
248
249template <class InputIterator, class OutputIterator, class Predicate>
250    OutputIterator
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    OutputIterator
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    pair<OutputIterator1, OutputIterator2>
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    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    bool
437    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
438
439template <class InputIterator1, class InputIterator2, class Compare>
440    bool
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    OutputIterator
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    OutputIterator
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    bool
611    lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
612
613template <class InputIterator1, class InputIterator2, class Compare>
614    bool
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
648#if defined(__IBMCPP__)
649#include "support/ibm/support.h"
650#endif
651#if defined(_LIBCPP_COMPILER_MSVC)
652#include <intrin.h>
653#endif
654
655#include <__debug>
656
657#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
658#pragma GCC system_header
659#endif
660
661_LIBCPP_PUSH_MACROS
662#include <__undef_macros>
663
664
665_LIBCPP_BEGIN_NAMESPACE_STD
666
667// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
668//   * That only works with C++14 and later, and
669//   * We haven't included <functional> here.
670template <class _T1, class _T2 = _T1>
671struct __equal_to
672{
673    _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
674    _LIBCPP_INLINE_VISIBILITY bool operator()(const _T1& __x, const _T2& __y) const {return __x == __y;}
675    _LIBCPP_INLINE_VISIBILITY bool operator()(const _T2& __x, const _T1& __y) const {return __x == __y;}
676    _LIBCPP_INLINE_VISIBILITY bool operator()(const _T2& __x, const _T2& __y) const {return __x == __y;}
677};
678
679template <class _T1>
680struct __equal_to<_T1, _T1>
681{
682    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
683    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
684};
685
686template <class _T1>
687struct __equal_to<const _T1, _T1>
688{
689    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
690    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
691};
692
693template <class _T1>
694struct __equal_to<_T1, const _T1>
695{
696    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
697    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
698};
699
700template <class _T1, class _T2 = _T1>
701struct __less
702{
703    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
704    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
705
706    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
707    bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
708
709    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
710    bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
711
712    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
713    bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
714};
715
716template <class _T1>
717struct __less<_T1, _T1>
718{
719    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
720    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
721};
722
723template <class _T1>
724struct __less<const _T1, _T1>
725{
726    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
727    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
728};
729
730template <class _T1>
731struct __less<_T1, const _T1>
732{
733    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
734    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
735};
736
737template <class _Predicate>
738class __invert // invert the sense of a comparison
739{
740private:
741    _Predicate __p_;
742public:
743    _LIBCPP_INLINE_VISIBILITY __invert() {}
744
745    _LIBCPP_INLINE_VISIBILITY
746    explicit __invert(_Predicate __p) : __p_(__p) {}
747
748    template <class _T1>
749    _LIBCPP_INLINE_VISIBILITY
750    bool operator()(const _T1& __x) {return !__p_(__x);}
751
752    template <class _T1, class _T2>
753    _LIBCPP_INLINE_VISIBILITY
754    bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
755};
756
757#ifdef _LIBCPP_DEBUG
758
759template <class _Compare>
760struct __debug_less
761{
762    _Compare __comp_;
763    __debug_less(_Compare& __c) : __comp_(__c) {}
764
765    template <class _Tp, class _Up>
766    bool operator()(const _Tp& __x, const _Up& __y)
767    {
768        bool __r = __comp_(__x, __y);
769        if (__r)
770            __do_compare_assert(0, __y, __x);
771        return __r;
772    }
773
774    template <class _LHS, class _RHS>
775    inline _LIBCPP_INLINE_VISIBILITY
776    decltype((void)_VSTD::declval<_Compare&>()(
777        _VSTD::declval<_LHS const&>(), _VSTD::declval<_RHS const&>()))
778    __do_compare_assert(int, _LHS const& __l, _RHS const& __r) {
779        _LIBCPP_ASSERT(!__comp_(__l, __r),
780            "Comparator does not induce a strict weak ordering");
781    }
782
783    template <class _LHS, class _RHS>
784    inline _LIBCPP_INLINE_VISIBILITY
785    void __do_compare_assert(long, _LHS const&, _RHS const&) {}
786};
787
788#endif  // _LIBCPP_DEBUG
789
790// Precondition:  __x != 0
791inline _LIBCPP_INLINE_VISIBILITY
792unsigned __ctz(unsigned __x) {
793#ifndef _LIBCPP_COMPILER_MSVC
794    return static_cast<unsigned>(__builtin_ctz(__x));
795#else
796  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
797  static_assert(sizeof(unsigned long) == 4, "");
798  unsigned long where;
799  // Search from LSB to MSB for first set bit.
800  // Returns zero if no set bit is found.
801  if (_BitScanForward(&where, __x))
802    return where;
803  return 32;
804#endif
805}
806
807inline _LIBCPP_INLINE_VISIBILITY
808unsigned long __ctz(unsigned long __x) {
809#ifndef _LIBCPP_COMPILER_MSVC
810    return static_cast<unsigned long>(__builtin_ctzl(__x));
811#else
812    static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
813    return __ctz(static_cast<unsigned>(__x));
814#endif
815}
816
817inline _LIBCPP_INLINE_VISIBILITY
818unsigned long long __ctz(unsigned long long __x) {
819#ifndef _LIBCPP_COMPILER_MSVC
820    return static_cast<unsigned long long>(__builtin_ctzll(__x));
821#else
822    unsigned long where;
823// Search from LSB to MSB for first set bit.
824// Returns zero if no set bit is found.
825#if defined(_LIBCPP_HAS_BITSCAN64)
826    (defined(_M_AMD64) || defined(__x86_64__))
827  if (_BitScanForward64(&where, __x))
828    return static_cast<int>(where);
829#else
830  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
831  // Scan the Low Word.
832  if (_BitScanForward(&where, static_cast<unsigned long>(__x)))
833    return where;
834  // Scan the High Word.
835  if (_BitScanForward(&where, static_cast<unsigned long>(__x >> 32)))
836    return where + 32; // Create a bit offset from the LSB.
837#endif
838  return 64;
839#endif // _LIBCPP_COMPILER_MSVC
840}
841
842// Precondition:  __x != 0
843inline _LIBCPP_INLINE_VISIBILITY
844unsigned __clz(unsigned __x) {
845#ifndef _LIBCPP_COMPILER_MSVC
846    return static_cast<unsigned>(__builtin_clz(__x));
847#else
848  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
849  static_assert(sizeof(unsigned long) == 4, "");
850  unsigned long where;
851  // Search from LSB to MSB for first set bit.
852  // Returns zero if no set bit is found.
853  if (_BitScanReverse(&where, __x))
854    return 31 - where;
855  return 32; // Undefined Behavior.
856#endif
857}
858
859inline _LIBCPP_INLINE_VISIBILITY
860unsigned long __clz(unsigned long __x) {
861#ifndef _LIBCPP_COMPILER_MSVC
862    return static_cast<unsigned long>(__builtin_clzl (__x));
863#else
864    static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
865    return __clz(static_cast<unsigned>(__x));
866#endif
867}
868
869inline _LIBCPP_INLINE_VISIBILITY
870unsigned long long __clz(unsigned long long __x) {
871#ifndef _LIBCPP_COMPILER_MSVC
872    return static_cast<unsigned long long>(__builtin_clzll(__x));
873#else
874  unsigned long where;
875// BitScanReverse scans from MSB to LSB for first set bit.
876// Returns 0 if no set bit is found.
877#if defined(_LIBCPP_HAS_BITSCAN64)
878  if (_BitScanReverse64(&where, __x))
879    return static_cast<int>(63 - where);
880#else
881  // Scan the high 32 bits.
882  if (_BitScanReverse(&where, static_cast<unsigned long>(__x >> 32)))
883    return 63 - (where + 32); // Create a bit offset from the MSB.
884  // Scan the low 32 bits.
885  if (_BitScanReverse(&where, static_cast<unsigned long>(__x)))
886    return 63 - where;
887#endif
888  return 64; // Undefined Behavior.
889#endif // _LIBCPP_COMPILER_MSVC
890}
891
892inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned __x) {
893#ifndef _LIBCPP_COMPILER_MSVC
894  return __builtin_popcount  (__x);
895#else
896  static_assert(sizeof(unsigned) == 4, "");
897  return __popcnt(__x);
898#endif
899}
900
901inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned long __x) {
902#ifndef _LIBCPP_COMPILER_MSVC
903  return __builtin_popcountl (__x);
904#else
905  static_assert(sizeof(unsigned long) == 4, "");
906  return __popcnt(__x);
907#endif
908}
909
910inline _LIBCPP_INLINE_VISIBILITY int __pop_count(unsigned long long __x) {
911#ifndef _LIBCPP_COMPILER_MSVC
912  return __builtin_popcountll(__x);
913#else
914  static_assert(sizeof(unsigned long long) == 8, "");
915  return __popcnt64(__x);
916#endif
917}
918
919// all_of
920
921template <class _InputIterator, class _Predicate>
922inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
923bool
924all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
925{
926    for (; __first != __last; ++__first)
927        if (!__pred(*__first))
928            return false;
929    return true;
930}
931
932// any_of
933
934template <class _InputIterator, class _Predicate>
935inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
936bool
937any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
938{
939    for (; __first != __last; ++__first)
940        if (__pred(*__first))
941            return true;
942    return false;
943}
944
945// none_of
946
947template <class _InputIterator, class _Predicate>
948inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
949bool
950none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
951{
952    for (; __first != __last; ++__first)
953        if (__pred(*__first))
954            return false;
955    return true;
956}
957
958// for_each
959
960template <class _InputIterator, class _Function>
961inline _LIBCPP_INLINE_VISIBILITY
962_Function
963for_each(_InputIterator __first, _InputIterator __last, _Function __f)
964{
965    for (; __first != __last; ++__first)
966        __f(*__first);
967    return __f;
968}
969
970#if _LIBCPP_STD_VER > 14
971// for_each_n
972
973template <class _InputIterator, class _Size, class _Function>
974inline _LIBCPP_INLINE_VISIBILITY
975_InputIterator
976for_each_n(_InputIterator __first, _Size __orig_n, _Function __f)
977{
978    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
979    _IntegralSize __n = __orig_n;
980    while (__n > 0)
981    {
982         __f(*__first);
983         ++__first;
984         --__n;
985    }
986    return __first;
987}
988#endif
989
990// find
991
992template <class _InputIterator, class _Tp>
993inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
994_InputIterator
995find(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
996{
997    for (; __first != __last; ++__first)
998        if (*__first == __value_)
999            break;
1000    return __first;
1001}
1002
1003// find_if
1004
1005template <class _InputIterator, class _Predicate>
1006inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1007_InputIterator
1008find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
1009{
1010    for (; __first != __last; ++__first)
1011        if (__pred(*__first))
1012            break;
1013    return __first;
1014}
1015
1016// find_if_not
1017
1018template<class _InputIterator, class _Predicate>
1019inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1020_InputIterator
1021find_if_not(_InputIterator __first, _InputIterator __last, _Predicate __pred)
1022{
1023    for (; __first != __last; ++__first)
1024        if (!__pred(*__first))
1025            break;
1026    return __first;
1027}
1028
1029// find_end
1030
1031template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
1032_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
1033__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1034           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred,
1035           forward_iterator_tag, forward_iterator_tag)
1036{
1037    // modeled after search algorithm
1038    _ForwardIterator1 __r = __last1;  // __last1 is the "default" answer
1039    if (__first2 == __last2)
1040        return __r;
1041    while (true)
1042    {
1043        while (true)
1044        {
1045            if (__first1 == __last1)         // if source exhausted return last correct answer
1046                return __r;                  //    (or __last1 if never found)
1047            if (__pred(*__first1, *__first2))
1048                break;
1049            ++__first1;
1050        }
1051        // *__first1 matches *__first2, now match elements after here
1052        _ForwardIterator1 __m1 = __first1;
1053        _ForwardIterator2 __m2 = __first2;
1054        while (true)
1055        {
1056            if (++__m2 == __last2)
1057            {                         // Pattern exhaused, record answer and search for another one
1058                __r = __first1;
1059                ++__first1;
1060                break;
1061            }
1062            if (++__m1 == __last1)     // Source exhausted, return last answer
1063                return __r;
1064            if (!__pred(*__m1, *__m2))  // mismatch, restart with a new __first
1065            {
1066                ++__first1;
1067                break;
1068            }  // else there is a match, check next elements
1069        }
1070    }
1071}
1072
1073template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
1074_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1
1075__find_end(_BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1,
1076           _BidirectionalIterator2 __first2, _BidirectionalIterator2 __last2, _BinaryPredicate __pred,
1077           bidirectional_iterator_tag, bidirectional_iterator_tag)
1078{
1079    // modeled after search algorithm (in reverse)
1080    if (__first2 == __last2)
1081        return __last1;  // Everything matches an empty sequence
1082    _BidirectionalIterator1 __l1 = __last1;
1083    _BidirectionalIterator2 __l2 = __last2;
1084    --__l2;
1085    while (true)
1086    {
1087        // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
1088        while (true)
1089        {
1090            if (__first1 == __l1)  // return __last1 if no element matches *__first2
1091                return __last1;
1092            if (__pred(*--__l1, *__l2))
1093                break;
1094        }
1095        // *__l1 matches *__l2, now match elements before here
1096        _BidirectionalIterator1 __m1 = __l1;
1097        _BidirectionalIterator2 __m2 = __l2;
1098        while (true)
1099        {
1100            if (__m2 == __first2)  // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
1101                return __m1;
1102            if (__m1 == __first1)  // Otherwise if source exhaused, pattern not found
1103                return __last1;
1104            if (!__pred(*--__m1, *--__m2))  // if there is a mismatch, restart with a new __l1
1105            {
1106                break;
1107            }  // else there is a match, check next elements
1108        }
1109    }
1110}
1111
1112template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1113_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1
1114__find_end(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1115           _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1116           random_access_iterator_tag, random_access_iterator_tag)
1117{
1118    // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
1119    typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
1120    if (__len2 == 0)
1121        return __last1;
1122    typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
1123    if (__len1 < __len2)
1124        return __last1;
1125    const _RandomAccessIterator1 __s = __first1 + (__len2 - 1);  // End of pattern match can't go before here
1126    _RandomAccessIterator1 __l1 = __last1;
1127    _RandomAccessIterator2 __l2 = __last2;
1128    --__l2;
1129    while (true)
1130    {
1131        while (true)
1132        {
1133            if (__s == __l1)
1134                return __last1;
1135            if (__pred(*--__l1, *__l2))
1136                break;
1137        }
1138        _RandomAccessIterator1 __m1 = __l1;
1139        _RandomAccessIterator2 __m2 = __l2;
1140        while (true)
1141        {
1142            if (__m2 == __first2)
1143                return __m1;
1144                                 // no need to check range on __m1 because __s guarantees we have enough source
1145            if (!__pred(*--__m1, *--__m2))
1146            {
1147                break;
1148            }
1149        }
1150    }
1151}
1152
1153template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1154inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1155_ForwardIterator1
1156find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1157         _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1158{
1159    return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>
1160                         (__first1, __last1, __first2, __last2, __pred,
1161                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1162                          typename iterator_traits<_ForwardIterator2>::iterator_category());
1163}
1164
1165template <class _ForwardIterator1, class _ForwardIterator2>
1166inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1167_ForwardIterator1
1168find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1169         _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1170{
1171    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1172    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1173    return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1174}
1175
1176// find_first_of
1177
1178template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1179_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator1
1180__find_first_of_ce(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1181              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1182{
1183    for (; __first1 != __last1; ++__first1)
1184        for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1185            if (__pred(*__first1, *__j))
1186                return __first1;
1187    return __last1;
1188}
1189
1190
1191template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1192inline _LIBCPP_INLINE_VISIBILITY  _LIBCPP_CONSTEXPR_AFTER_CXX17
1193_ForwardIterator1
1194find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1195              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1196{
1197    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __pred);
1198}
1199
1200template <class _ForwardIterator1, class _ForwardIterator2>
1201inline _LIBCPP_INLINE_VISIBILITY  _LIBCPP_CONSTEXPR_AFTER_CXX17
1202_ForwardIterator1
1203find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1204              _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1205{
1206    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1207    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1208    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1209}
1210
1211// adjacent_find
1212
1213template <class _ForwardIterator, class _BinaryPredicate>
1214inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1215_ForwardIterator
1216adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
1217{
1218    if (__first != __last)
1219    {
1220        _ForwardIterator __i = __first;
1221        while (++__i != __last)
1222        {
1223            if (__pred(*__first, *__i))
1224                return __first;
1225            __first = __i;
1226        }
1227    }
1228    return __last;
1229}
1230
1231template <class _ForwardIterator>
1232inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1233_ForwardIterator
1234adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
1235{
1236    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1237    return _VSTD::adjacent_find(__first, __last, __equal_to<__v>());
1238}
1239
1240// count
1241
1242template <class _InputIterator, class _Tp>
1243inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1244typename iterator_traits<_InputIterator>::difference_type
1245count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
1246{
1247    typename iterator_traits<_InputIterator>::difference_type __r(0);
1248    for (; __first != __last; ++__first)
1249        if (*__first == __value_)
1250            ++__r;
1251    return __r;
1252}
1253
1254// count_if
1255
1256template <class _InputIterator, class _Predicate>
1257inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1258typename iterator_traits<_InputIterator>::difference_type
1259count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
1260{
1261    typename iterator_traits<_InputIterator>::difference_type __r(0);
1262    for (; __first != __last; ++__first)
1263        if (__pred(*__first))
1264            ++__r;
1265    return __r;
1266}
1267
1268// mismatch
1269
1270template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1271inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1272pair<_InputIterator1, _InputIterator2>
1273mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1274         _InputIterator2 __first2, _BinaryPredicate __pred)
1275{
1276    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1277        if (!__pred(*__first1, *__first2))
1278            break;
1279    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1280}
1281
1282template <class _InputIterator1, class _InputIterator2>
1283inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1284pair<_InputIterator1, _InputIterator2>
1285mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1286{
1287    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1288    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1289    return _VSTD::mismatch(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1290}
1291
1292#if _LIBCPP_STD_VER > 11
1293template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1294inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1295pair<_InputIterator1, _InputIterator2>
1296mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1297         _InputIterator2 __first2, _InputIterator2 __last2,
1298         _BinaryPredicate __pred)
1299{
1300    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1301        if (!__pred(*__first1, *__first2))
1302            break;
1303    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1304}
1305
1306template <class _InputIterator1, class _InputIterator2>
1307inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1308pair<_InputIterator1, _InputIterator2>
1309mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1310         _InputIterator2 __first2, _InputIterator2 __last2)
1311{
1312    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1313    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1314    return _VSTD::mismatch(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1315}
1316#endif
1317
1318// equal
1319
1320template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1321inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1322bool
1323equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred)
1324{
1325    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1326        if (!__pred(*__first1, *__first2))
1327            return false;
1328    return true;
1329}
1330
1331template <class _InputIterator1, class _InputIterator2>
1332inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1333bool
1334equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1335{
1336    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1337    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1338    return _VSTD::equal(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1339}
1340
1341#if _LIBCPP_STD_VER > 11
1342template <class _BinaryPredicate, class _InputIterator1, class _InputIterator2>
1343inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1344bool
1345__equal(_InputIterator1 __first1, _InputIterator1 __last1,
1346        _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred,
1347        input_iterator_tag, input_iterator_tag )
1348{
1349    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1350        if (!__pred(*__first1, *__first2))
1351            return false;
1352    return __first1 == __last1 && __first2 == __last2;
1353}
1354
1355template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1356inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1357bool
1358__equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1359        _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1360      random_access_iterator_tag, random_access_iterator_tag )
1361{
1362    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1363        return false;
1364    return _VSTD::equal<_RandomAccessIterator1, _RandomAccessIterator2,
1365                        typename add_lvalue_reference<_BinaryPredicate>::type>
1366                       (__first1, __last1, __first2, __pred );
1367}
1368
1369template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1370inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1371bool
1372equal(_InputIterator1 __first1, _InputIterator1 __last1,
1373      _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred )
1374{
1375    return _VSTD::__equal<typename add_lvalue_reference<_BinaryPredicate>::type>
1376       (__first1, __last1, __first2, __last2, __pred,
1377        typename iterator_traits<_InputIterator1>::iterator_category(),
1378        typename iterator_traits<_InputIterator2>::iterator_category());
1379}
1380
1381template <class _InputIterator1, class _InputIterator2>
1382inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1383bool
1384equal(_InputIterator1 __first1, _InputIterator1 __last1,
1385      _InputIterator2 __first2, _InputIterator2 __last2)
1386{
1387    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1388    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1389    return _VSTD::__equal(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
1390        typename iterator_traits<_InputIterator1>::iterator_category(),
1391        typename iterator_traits<_InputIterator2>::iterator_category());
1392}
1393#endif
1394
1395// is_permutation
1396
1397template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1398_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1399is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1400               _ForwardIterator2 __first2, _BinaryPredicate __pred)
1401{
1402//  shorten sequences as much as possible by lopping of any equal prefix
1403    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1404        if (!__pred(*__first1, *__first2))
1405            break;
1406    if (__first1 == __last1)
1407        return true;
1408
1409//  __first1 != __last1 && *__first1 != *__first2
1410    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1411    _D1 __l1 = _VSTD::distance(__first1, __last1);
1412    if (__l1 == _D1(1))
1413        return false;
1414    _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1);
1415    // For each element in [f1, l1) see if there are the same number of
1416    //    equal elements in [f2, l2)
1417    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1418    {
1419    //  Have we already counted the number of *__i in [f1, l1)?
1420        if (find(__first1, __i, *__i) == __i) {
1421            // Count number of *__i in [f2, l2)
1422            _D1 __c2 = 0;
1423            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1424                if (__pred(*__i, *__j))
1425                    ++__c2;
1426            if (__c2 == 0)
1427                return false;
1428            // Count number of *__i in [__i, l1) (we can start with 1)
1429            _D1 __c1 = 1;
1430            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1431                if (__pred(*__i, *__j))
1432                    ++__c1;
1433            if (__c1 != __c2)
1434                return false;
1435        }
1436    }
1437    return true;
1438}
1439
1440template<class _ForwardIterator1, class _ForwardIterator2>
1441inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1442bool
1443is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1444               _ForwardIterator2 __first2)
1445{
1446    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1447    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1448    return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1449}
1450
1451#if _LIBCPP_STD_VER > 11
1452template<class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
1453_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1454__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1455                 _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1456                 _BinaryPredicate __pred,
1457                 forward_iterator_tag, forward_iterator_tag )
1458{
1459//  shorten sequences as much as possible by lopping of any equal prefix
1460    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1461        if (!__pred(*__first1, *__first2))
1462            break;
1463    if (__first1 == __last1)
1464        return __first2 == __last2;
1465    else if (__first2 == __last2)
1466        return false;
1467
1468    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1469    _D1 __l1 = _VSTD::distance(__first1, __last1);
1470
1471    typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2;
1472    _D2 __l2 = _VSTD::distance(__first2, __last2);
1473    if (__l1 != __l2)
1474        return false;
1475
1476    // For each element in [f1, l1) see if there are the same number of
1477    //    equal elements in [f2, l2)
1478    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1479    {
1480    //  Have we already counted the number of *__i in [f1, l1)?
1481        if (find(__first1, __i, *__i) == __i) {
1482            // Count number of *__i in [f2, l2)
1483            _D1 __c2 = 0;
1484            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1485                if (__pred(*__i, *__j))
1486                    ++__c2;
1487            if (__c2 == 0)
1488                return false;
1489            // Count number of *__i in [__i, l1) (we can start with 1)
1490            _D1 __c1 = 1;
1491            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1492                if (__pred(*__i, *__j))
1493                    ++__c1;
1494            if (__c1 != __c2)
1495                return false;
1496        }
1497    }
1498    return true;
1499}
1500
1501template<class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1502_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1503__is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1,
1504               _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2,
1505               _BinaryPredicate __pred,
1506               random_access_iterator_tag, random_access_iterator_tag )
1507{
1508    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1509        return false;
1510    return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2,
1511                                 typename add_lvalue_reference<_BinaryPredicate>::type>
1512                                (__first1, __last1, __first2, __pred );
1513}
1514
1515template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1516inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1517bool
1518is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1519               _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1520               _BinaryPredicate __pred )
1521{
1522    return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>
1523       (__first1, __last1, __first2, __last2, __pred,
1524        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1525        typename iterator_traits<_ForwardIterator2>::iterator_category());
1526}
1527
1528template<class _ForwardIterator1, class _ForwardIterator2>
1529inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1530bool
1531is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1532               _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1533{
1534    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1535    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1536    return _VSTD::__is_permutation(__first1, __last1, __first2, __last2,
1537        __equal_to<__v1, __v2>(),
1538        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1539        typename iterator_traits<_ForwardIterator2>::iterator_category());
1540}
1541#endif
1542
1543// search
1544// __search is in <functional>
1545
1546template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1547inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1548_ForwardIterator1
1549search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1550       _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1551{
1552    return _VSTD::__search<typename add_lvalue_reference<_BinaryPredicate>::type>
1553                         (__first1, __last1, __first2, __last2, __pred,
1554                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1555                          typename iterator_traits<_ForwardIterator2>::iterator_category())
1556            .first;
1557}
1558
1559template <class _ForwardIterator1, class _ForwardIterator2>
1560inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1561_ForwardIterator1
1562search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1563       _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1564{
1565    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1566    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1567    return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1568}
1569
1570
1571#if _LIBCPP_STD_VER > 14
1572template <class _ForwardIterator, class _Searcher>
1573_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1574_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
1575{ return __s(__f, __l).first; }
1576#endif
1577
1578// search_n
1579
1580template <class _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
1581_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
1582__search_n(_ForwardIterator __first, _ForwardIterator __last,
1583           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, forward_iterator_tag)
1584{
1585    if (__count <= 0)
1586        return __first;
1587    while (true)
1588    {
1589        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1590        while (true)
1591        {
1592            if (__first == __last)  // return __last if no element matches __value_
1593                return __last;
1594            if (__pred(*__first, __value_))
1595                break;
1596            ++__first;
1597        }
1598        // *__first matches __value_, now match elements after here
1599        _ForwardIterator __m = __first;
1600        _Size __c(0);
1601        while (true)
1602        {
1603            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1604                return __first;
1605            if (++__m == __last)  // Otherwise if source exhaused, pattern not found
1606                return __last;
1607            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1608            {
1609                __first = __m;
1610                ++__first;
1611                break;
1612            }  // else there is a match, check next elements
1613        }
1614    }
1615}
1616
1617template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
1618_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
1619__search_n(_RandomAccessIterator __first, _RandomAccessIterator __last,
1620           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, random_access_iterator_tag)
1621{
1622    if (__count <= 0)
1623        return __first;
1624    _Size __len = static_cast<_Size>(__last - __first);
1625    if (__len < __count)
1626        return __last;
1627    const _RandomAccessIterator __s = __last - (__count - 1);  // Start of pattern match can't go beyond here
1628    while (true)
1629    {
1630        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1631        while (true)
1632        {
1633            if (__first >= __s)  // return __last if no element matches __value_
1634                return __last;
1635            if (__pred(*__first, __value_))
1636                break;
1637            ++__first;
1638        }
1639        // *__first matches __value_, now match elements after here
1640        _RandomAccessIterator __m = __first;
1641        _Size __c(0);
1642        while (true)
1643        {
1644            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1645                return __first;
1646             ++__m;          // no need to check range on __m because __s guarantees we have enough source
1647            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1648            {
1649                __first = __m;
1650                ++__first;
1651                break;
1652            }  // else there is a match, check next elements
1653        }
1654    }
1655}
1656
1657template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
1658inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1659_ForwardIterator
1660search_n(_ForwardIterator __first, _ForwardIterator __last,
1661         _Size __count, const _Tp& __value_, _BinaryPredicate __pred)
1662{
1663    return _VSTD::__search_n<typename add_lvalue_reference<_BinaryPredicate>::type>
1664           (__first, __last, __convert_to_integral(__count), __value_, __pred,
1665           typename iterator_traits<_ForwardIterator>::iterator_category());
1666}
1667
1668template <class _ForwardIterator, class _Size, class _Tp>
1669inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1670_ForwardIterator
1671search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_)
1672{
1673    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1674    return _VSTD::search_n(__first, __last, __convert_to_integral(__count),
1675                           __value_, __equal_to<__v, _Tp>());
1676}
1677
1678// copy
1679template <class _Iter>
1680inline _LIBCPP_INLINE_VISIBILITY
1681_Iter
1682__unwrap_iter(_Iter __i)
1683{
1684    return __i;
1685}
1686
1687template <class _Tp>
1688inline _LIBCPP_INLINE_VISIBILITY
1689typename enable_if
1690<
1691    is_trivially_copy_assignable<_Tp>::value,
1692    _Tp*
1693>::type
1694__unwrap_iter(move_iterator<_Tp*> __i)
1695{
1696    return __i.base();
1697}
1698
1699#if _LIBCPP_DEBUG_LEVEL < 2
1700
1701template <class _Tp>
1702inline _LIBCPP_INLINE_VISIBILITY
1703typename enable_if
1704<
1705    is_trivially_copy_assignable<_Tp>::value,
1706    _Tp*
1707>::type
1708__unwrap_iter(__wrap_iter<_Tp*> __i)
1709{
1710    return __i.base();
1711}
1712
1713#else
1714
1715template <class _Tp>
1716inline _LIBCPP_INLINE_VISIBILITY
1717typename enable_if
1718<
1719    is_trivially_copy_assignable<_Tp>::value,
1720    __wrap_iter<_Tp*>
1721>::type
1722__unwrap_iter(__wrap_iter<_Tp*> __i)
1723{
1724    return __i;
1725}
1726
1727#endif  // _LIBCPP_DEBUG_LEVEL < 2
1728
1729template <class _InputIterator, class _OutputIterator>
1730inline _LIBCPP_INLINE_VISIBILITY
1731_OutputIterator
1732__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1733{
1734    for (; __first != __last; ++__first, (void) ++__result)
1735        *__result = *__first;
1736    return __result;
1737}
1738
1739template <class _Tp, class _Up>
1740inline _LIBCPP_INLINE_VISIBILITY
1741typename enable_if
1742<
1743    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1744    is_trivially_copy_assignable<_Up>::value,
1745    _Up*
1746>::type
1747__copy(_Tp* __first, _Tp* __last, _Up* __result)
1748{
1749    const size_t __n = static_cast<size_t>(__last - __first);
1750    if (__n > 0)
1751        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1752    return __result + __n;
1753}
1754
1755template <class _InputIterator, class _OutputIterator>
1756inline _LIBCPP_INLINE_VISIBILITY
1757_OutputIterator
1758copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1759{
1760    return _VSTD::__copy(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1761}
1762
1763// copy_backward
1764
1765template <class _BidirectionalIterator, class _OutputIterator>
1766inline _LIBCPP_INLINE_VISIBILITY
1767_OutputIterator
1768__copy_backward(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
1769{
1770    while (__first != __last)
1771        *--__result = *--__last;
1772    return __result;
1773}
1774
1775template <class _Tp, class _Up>
1776inline _LIBCPP_INLINE_VISIBILITY
1777typename enable_if
1778<
1779    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1780    is_trivially_copy_assignable<_Up>::value,
1781    _Up*
1782>::type
1783__copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
1784{
1785    const size_t __n = static_cast<size_t>(__last - __first);
1786    if (__n > 0)
1787    {
1788        __result -= __n;
1789        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1790    }
1791    return __result;
1792}
1793
1794template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1795inline _LIBCPP_INLINE_VISIBILITY
1796_BidirectionalIterator2
1797copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1798              _BidirectionalIterator2 __result)
1799{
1800    return _VSTD::__copy_backward(__unwrap_iter(__first),
1801                                  __unwrap_iter(__last),
1802                                  __unwrap_iter(__result));
1803}
1804
1805// copy_if
1806
1807template<class _InputIterator, class _OutputIterator, class _Predicate>
1808inline _LIBCPP_INLINE_VISIBILITY
1809_OutputIterator
1810copy_if(_InputIterator __first, _InputIterator __last,
1811        _OutputIterator __result, _Predicate __pred)
1812{
1813    for (; __first != __last; ++__first)
1814    {
1815        if (__pred(*__first))
1816        {
1817            *__result = *__first;
1818            ++__result;
1819        }
1820    }
1821    return __result;
1822}
1823
1824// copy_n
1825
1826template<class _InputIterator, class _Size, class _OutputIterator>
1827inline _LIBCPP_INLINE_VISIBILITY
1828typename enable_if
1829<
1830    __is_input_iterator<_InputIterator>::value &&
1831   !__is_random_access_iterator<_InputIterator>::value,
1832    _OutputIterator
1833>::type
1834copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1835{
1836    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1837    _IntegralSize __n = __orig_n;
1838    if (__n > 0)
1839    {
1840        *__result = *__first;
1841        ++__result;
1842        for (--__n; __n > 0; --__n)
1843        {
1844            ++__first;
1845            *__result = *__first;
1846            ++__result;
1847        }
1848    }
1849    return __result;
1850}
1851
1852template<class _InputIterator, class _Size, class _OutputIterator>
1853inline _LIBCPP_INLINE_VISIBILITY
1854typename enable_if
1855<
1856    __is_random_access_iterator<_InputIterator>::value,
1857    _OutputIterator
1858>::type
1859copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1860{
1861    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1862    _IntegralSize __n = __orig_n;
1863    return _VSTD::copy(__first, __first + __n, __result);
1864}
1865
1866// move
1867
1868template <class _InputIterator, class _OutputIterator>
1869inline _LIBCPP_INLINE_VISIBILITY
1870_OutputIterator
1871__move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1872{
1873    for (; __first != __last; ++__first, (void) ++__result)
1874        *__result = _VSTD::move(*__first);
1875    return __result;
1876}
1877
1878template <class _Tp, class _Up>
1879inline _LIBCPP_INLINE_VISIBILITY
1880typename enable_if
1881<
1882    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1883    is_trivially_copy_assignable<_Up>::value,
1884    _Up*
1885>::type
1886__move(_Tp* __first, _Tp* __last, _Up* __result)
1887{
1888    const size_t __n = static_cast<size_t>(__last - __first);
1889    if (__n > 0)
1890        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1891    return __result + __n;
1892}
1893
1894template <class _InputIterator, class _OutputIterator>
1895inline _LIBCPP_INLINE_VISIBILITY
1896_OutputIterator
1897move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1898{
1899    return _VSTD::__move(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1900}
1901
1902// move_backward
1903
1904template <class _InputIterator, class _OutputIterator>
1905inline _LIBCPP_INLINE_VISIBILITY
1906_OutputIterator
1907__move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1908{
1909    while (__first != __last)
1910        *--__result = _VSTD::move(*--__last);
1911    return __result;
1912}
1913
1914template <class _Tp, class _Up>
1915inline _LIBCPP_INLINE_VISIBILITY
1916typename enable_if
1917<
1918    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1919    is_trivially_copy_assignable<_Up>::value,
1920    _Up*
1921>::type
1922__move_backward(_Tp* __first, _Tp* __last, _Up* __result)
1923{
1924    const size_t __n = static_cast<size_t>(__last - __first);
1925    if (__n > 0)
1926    {
1927        __result -= __n;
1928        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1929    }
1930    return __result;
1931}
1932
1933template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1934inline _LIBCPP_INLINE_VISIBILITY
1935_BidirectionalIterator2
1936move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1937              _BidirectionalIterator2 __result)
1938{
1939    return _VSTD::__move_backward(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1940}
1941
1942// iter_swap
1943
1944// moved to <type_traits> for better swap / noexcept support
1945
1946// transform
1947
1948template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
1949inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1950_OutputIterator
1951transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
1952{
1953    for (; __first != __last; ++__first, (void) ++__result)
1954        *__result = __op(*__first);
1955    return __result;
1956}
1957
1958template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _BinaryOperation>
1959inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1960_OutputIterator
1961transform(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2,
1962          _OutputIterator __result, _BinaryOperation __binary_op)
1963{
1964    for (; __first1 != __last1; ++__first1, (void) ++__first2, ++__result)
1965        *__result = __binary_op(*__first1, *__first2);
1966    return __result;
1967}
1968
1969// replace
1970
1971template <class _ForwardIterator, class _Tp>
1972inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1973void
1974replace(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __old_value, const _Tp& __new_value)
1975{
1976    for (; __first != __last; ++__first)
1977        if (*__first == __old_value)
1978            *__first = __new_value;
1979}
1980
1981// replace_if
1982
1983template <class _ForwardIterator, class _Predicate, class _Tp>
1984inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1985void
1986replace_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, const _Tp& __new_value)
1987{
1988    for (; __first != __last; ++__first)
1989        if (__pred(*__first))
1990            *__first = __new_value;
1991}
1992
1993// replace_copy
1994
1995template <class _InputIterator, class _OutputIterator, class _Tp>
1996inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1997_OutputIterator
1998replace_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
1999             const _Tp& __old_value, const _Tp& __new_value)
2000{
2001    for (; __first != __last; ++__first, (void) ++__result)
2002        if (*__first == __old_value)
2003            *__result = __new_value;
2004        else
2005            *__result = *__first;
2006    return __result;
2007}
2008
2009// replace_copy_if
2010
2011template <class _InputIterator, class _OutputIterator, class _Predicate, class _Tp>
2012inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2013_OutputIterator
2014replace_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
2015                _Predicate __pred, const _Tp& __new_value)
2016{
2017    for (; __first != __last; ++__first, (void) ++__result)
2018        if (__pred(*__first))
2019            *__result = __new_value;
2020        else
2021            *__result = *__first;
2022    return __result;
2023}
2024
2025// fill_n
2026
2027template <class _OutputIterator, class _Size, class _Tp>
2028inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2029_OutputIterator
2030__fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
2031{
2032    for (; __n > 0; ++__first, (void) --__n)
2033        *__first = __value_;
2034    return __first;
2035}
2036
2037template <class _OutputIterator, class _Size, class _Tp>
2038inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2039_OutputIterator
2040fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
2041{
2042   return _VSTD::__fill_n(__first, __convert_to_integral(__n), __value_);
2043}
2044
2045// fill
2046
2047template <class _ForwardIterator, class _Tp>
2048inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2049void
2050__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, forward_iterator_tag)
2051{
2052    for (; __first != __last; ++__first)
2053        *__first = __value_;
2054}
2055
2056template <class _RandomAccessIterator, class _Tp>
2057inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2058void
2059__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
2060{
2061    _VSTD::fill_n(__first, __last - __first, __value_);
2062}
2063
2064template <class _ForwardIterator, class _Tp>
2065inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2066void
2067fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2068{
2069    _VSTD::__fill(__first, __last, __value_, typename iterator_traits<_ForwardIterator>::iterator_category());
2070}
2071
2072// generate
2073
2074template <class _ForwardIterator, class _Generator>
2075inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2076void
2077generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __gen)
2078{
2079    for (; __first != __last; ++__first)
2080        *__first = __gen();
2081}
2082
2083// generate_n
2084
2085template <class _OutputIterator, class _Size, class _Generator>
2086inline _LIBCPP_INLINE_VISIBILITY  _LIBCPP_CONSTEXPR_AFTER_CXX17
2087_OutputIterator
2088generate_n(_OutputIterator __first, _Size __orig_n, _Generator __gen)
2089{
2090    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
2091    _IntegralSize __n = __orig_n;
2092    for (; __n > 0; ++__first, (void) --__n)
2093        *__first = __gen();
2094    return __first;
2095}
2096
2097// remove
2098
2099template <class _ForwardIterator, class _Tp>
2100_ForwardIterator
2101remove(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2102{
2103    __first = _VSTD::find(__first, __last, __value_);
2104    if (__first != __last)
2105    {
2106        _ForwardIterator __i = __first;
2107        while (++__i != __last)
2108        {
2109            if (!(*__i == __value_))
2110            {
2111                *__first = _VSTD::move(*__i);
2112                ++__first;
2113            }
2114        }
2115    }
2116    return __first;
2117}
2118
2119// remove_if
2120
2121template <class _ForwardIterator, class _Predicate>
2122_ForwardIterator
2123remove_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
2124{
2125    __first = _VSTD::find_if<_ForwardIterator, typename add_lvalue_reference<_Predicate>::type>
2126                           (__first, __last, __pred);
2127    if (__first != __last)
2128    {
2129        _ForwardIterator __i = __first;
2130        while (++__i != __last)
2131        {
2132            if (!__pred(*__i))
2133            {
2134                *__first = _VSTD::move(*__i);
2135                ++__first;
2136            }
2137        }
2138    }
2139    return __first;
2140}
2141
2142// remove_copy
2143
2144template <class _InputIterator, class _OutputIterator, class _Tp>
2145inline _LIBCPP_INLINE_VISIBILITY
2146_OutputIterator
2147remove_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, const _Tp& __value_)
2148{
2149    for (; __first != __last; ++__first)
2150    {
2151        if (!(*__first == __value_))
2152        {
2153            *__result = *__first;
2154            ++__result;
2155        }
2156    }
2157    return __result;
2158}
2159
2160// remove_copy_if
2161
2162template <class _InputIterator, class _OutputIterator, class _Predicate>
2163inline _LIBCPP_INLINE_VISIBILITY
2164_OutputIterator
2165remove_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _Predicate __pred)
2166{
2167    for (; __first != __last; ++__first)
2168    {
2169        if (!__pred(*__first))
2170        {
2171            *__result = *__first;
2172            ++__result;
2173        }
2174    }
2175    return __result;
2176}
2177
2178// unique
2179
2180template <class _ForwardIterator, class _BinaryPredicate>
2181_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2182unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
2183{
2184    __first = _VSTD::adjacent_find<_ForwardIterator, typename add_lvalue_reference<_BinaryPredicate>::type>
2185                                 (__first, __last, __pred);
2186    if (__first != __last)
2187    {
2188        // ...  a  a  ?  ...
2189        //      f     i
2190        _ForwardIterator __i = __first;
2191        for (++__i; ++__i != __last;)
2192            if (!__pred(*__first, *__i))
2193                *++__first = _VSTD::move(*__i);
2194        ++__first;
2195    }
2196    return __first;
2197}
2198
2199template <class _ForwardIterator>
2200inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2201_ForwardIterator
2202unique(_ForwardIterator __first, _ForwardIterator __last)
2203{
2204    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
2205    return _VSTD::unique(__first, __last, __equal_to<__v>());
2206}
2207
2208// unique_copy
2209
2210template <class _BinaryPredicate, class _InputIterator, class _OutputIterator>
2211_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2212__unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2213              input_iterator_tag, output_iterator_tag)
2214{
2215    if (__first != __last)
2216    {
2217        typename iterator_traits<_InputIterator>::value_type __t(*__first);
2218        *__result = __t;
2219        ++__result;
2220        while (++__first != __last)
2221        {
2222            if (!__pred(__t, *__first))
2223            {
2224                __t = *__first;
2225                *__result = __t;
2226                ++__result;
2227            }
2228        }
2229    }
2230    return __result;
2231}
2232
2233template <class _BinaryPredicate, class _ForwardIterator, class _OutputIterator>
2234_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2235__unique_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2236              forward_iterator_tag, output_iterator_tag)
2237{
2238    if (__first != __last)
2239    {
2240        _ForwardIterator __i = __first;
2241        *__result = *__i;
2242        ++__result;
2243        while (++__first != __last)
2244        {
2245            if (!__pred(*__i, *__first))
2246            {
2247                *__result = *__first;
2248                ++__result;
2249                __i = __first;
2250            }
2251        }
2252    }
2253    return __result;
2254}
2255
2256template <class _BinaryPredicate, class _InputIterator, class _ForwardIterator>
2257_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2258__unique_copy(_InputIterator __first, _InputIterator __last, _ForwardIterator __result, _BinaryPredicate __pred,
2259              input_iterator_tag, forward_iterator_tag)
2260{
2261    if (__first != __last)
2262    {
2263        *__result = *__first;
2264        while (++__first != __last)
2265            if (!__pred(*__result, *__first))
2266                *++__result = *__first;
2267        ++__result;
2268    }
2269    return __result;
2270}
2271
2272template <class _InputIterator, class _OutputIterator, class _BinaryPredicate>
2273inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2274_OutputIterator
2275unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred)
2276{
2277    return _VSTD::__unique_copy<typename add_lvalue_reference<_BinaryPredicate>::type>
2278                              (__first, __last, __result, __pred,
2279                               typename iterator_traits<_InputIterator>::iterator_category(),
2280                               typename iterator_traits<_OutputIterator>::iterator_category());
2281}
2282
2283template <class _InputIterator, class _OutputIterator>
2284inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2285_OutputIterator
2286unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
2287{
2288    typedef typename iterator_traits<_InputIterator>::value_type __v;
2289    return _VSTD::unique_copy(__first, __last, __result, __equal_to<__v>());
2290}
2291
2292// reverse
2293
2294template <class _BidirectionalIterator>
2295inline _LIBCPP_INLINE_VISIBILITY
2296void
2297__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
2298{
2299    while (__first != __last)
2300    {
2301        if (__first == --__last)
2302            break;
2303        _VSTD::iter_swap(__first, __last);
2304        ++__first;
2305    }
2306}
2307
2308template <class _RandomAccessIterator>
2309inline _LIBCPP_INLINE_VISIBILITY
2310void
2311__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
2312{
2313    if (__first != __last)
2314        for (; __first < --__last; ++__first)
2315            _VSTD::iter_swap(__first, __last);
2316}
2317
2318template <class _BidirectionalIterator>
2319inline _LIBCPP_INLINE_VISIBILITY
2320void
2321reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
2322{
2323    _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
2324}
2325
2326// reverse_copy
2327
2328template <class _BidirectionalIterator, class _OutputIterator>
2329inline _LIBCPP_INLINE_VISIBILITY
2330_OutputIterator
2331reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
2332{
2333    for (; __first != __last; ++__result)
2334        *__result = *--__last;
2335    return __result;
2336}
2337
2338// rotate
2339
2340template <class _ForwardIterator>
2341_ForwardIterator
2342__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
2343{
2344    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
2345    value_type __tmp = _VSTD::move(*__first);
2346    _ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
2347    *__lm1 = _VSTD::move(__tmp);
2348    return __lm1;
2349}
2350
2351template <class _BidirectionalIterator>
2352_BidirectionalIterator
2353__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
2354{
2355    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
2356    _BidirectionalIterator __lm1 = _VSTD::prev(__last);
2357    value_type __tmp = _VSTD::move(*__lm1);
2358    _BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
2359    *__first = _VSTD::move(__tmp);
2360    return __fp1;
2361}
2362
2363template <class _ForwardIterator>
2364_ForwardIterator
2365__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2366{
2367    _ForwardIterator __i = __middle;
2368    while (true)
2369    {
2370        swap(*__first, *__i);
2371        ++__first;
2372        if (++__i == __last)
2373            break;
2374        if (__first == __middle)
2375            __middle = __i;
2376    }
2377    _ForwardIterator __r = __first;
2378    if (__first != __middle)
2379    {
2380        __i = __middle;
2381        while (true)
2382        {
2383            swap(*__first, *__i);
2384            ++__first;
2385            if (++__i == __last)
2386            {
2387                if (__first == __middle)
2388                    break;
2389                __i = __middle;
2390            }
2391            else if (__first == __middle)
2392                __middle = __i;
2393        }
2394    }
2395    return __r;
2396}
2397
2398template<typename _Integral>
2399inline _LIBCPP_INLINE_VISIBILITY
2400_Integral
2401__algo_gcd(_Integral __x, _Integral __y)
2402{
2403    do
2404    {
2405        _Integral __t = __x % __y;
2406        __x = __y;
2407        __y = __t;
2408    } while (__y);
2409    return __x;
2410}
2411
2412template<typename _RandomAccessIterator>
2413_RandomAccessIterator
2414__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
2415{
2416    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
2417    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
2418
2419    const difference_type __m1 = __middle - __first;
2420    const difference_type __m2 = __last - __middle;
2421    if (__m1 == __m2)
2422    {
2423        _VSTD::swap_ranges(__first, __middle, __middle);
2424        return __middle;
2425    }
2426    const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
2427    for (_RandomAccessIterator __p = __first + __g; __p != __first;)
2428    {
2429        value_type __t(_VSTD::move(*--__p));
2430        _RandomAccessIterator __p1 = __p;
2431        _RandomAccessIterator __p2 = __p1 + __m1;
2432        do
2433        {
2434            *__p1 = _VSTD::move(*__p2);
2435            __p1 = __p2;
2436            const difference_type __d = __last - __p2;
2437            if (__m1 < __d)
2438                __p2 += __m1;
2439            else
2440                __p2 = __first + (__m1 - __d);
2441        } while (__p2 != __p);
2442        *__p1 = _VSTD::move(__t);
2443    }
2444    return __first + __m2;
2445}
2446
2447template <class _ForwardIterator>
2448inline _LIBCPP_INLINE_VISIBILITY
2449_ForwardIterator
2450__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
2451         _VSTD::forward_iterator_tag)
2452{
2453    typedef typename _VSTD::iterator_traits<_ForwardIterator>::value_type value_type;
2454    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2455    {
2456        if (_VSTD::next(__first) == __middle)
2457            return _VSTD::__rotate_left(__first, __last);
2458    }
2459    return _VSTD::__rotate_forward(__first, __middle, __last);
2460}
2461
2462template <class _BidirectionalIterator>
2463inline _LIBCPP_INLINE_VISIBILITY
2464_BidirectionalIterator
2465__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
2466         _VSTD::bidirectional_iterator_tag)
2467{
2468    typedef typename _VSTD::iterator_traits<_BidirectionalIterator>::value_type value_type;
2469    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2470    {
2471        if (_VSTD::next(__first) == __middle)
2472            return _VSTD::__rotate_left(__first, __last);
2473        if (_VSTD::next(__middle) == __last)
2474            return _VSTD::__rotate_right(__first, __last);
2475    }
2476    return _VSTD::__rotate_forward(__first, __middle, __last);
2477}
2478
2479template <class _RandomAccessIterator>
2480inline _LIBCPP_INLINE_VISIBILITY
2481_RandomAccessIterator
2482__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
2483         _VSTD::random_access_iterator_tag)
2484{
2485    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::value_type value_type;
2486    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2487    {
2488        if (_VSTD::next(__first) == __middle)
2489            return _VSTD::__rotate_left(__first, __last);
2490        if (_VSTD::next(__middle) == __last)
2491            return _VSTD::__rotate_right(__first, __last);
2492        return _VSTD::__rotate_gcd(__first, __middle, __last);
2493    }
2494    return _VSTD::__rotate_forward(__first, __middle, __last);
2495}
2496
2497template <class _ForwardIterator>
2498inline _LIBCPP_INLINE_VISIBILITY
2499_ForwardIterator
2500rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2501{
2502    if (__first == __middle)
2503        return __last;
2504    if (__middle == __last)
2505        return __first;
2506    return _VSTD::__rotate(__first, __middle, __last,
2507                           typename _VSTD::iterator_traits<_ForwardIterator>::iterator_category());
2508}
2509
2510// rotate_copy
2511
2512template <class _ForwardIterator, class _OutputIterator>
2513inline _LIBCPP_INLINE_VISIBILITY
2514_OutputIterator
2515rotate_copy(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last, _OutputIterator __result)
2516{
2517    return _VSTD::copy(__first, __middle, _VSTD::copy(__middle, __last, __result));
2518}
2519
2520// min_element
2521
2522template <class _ForwardIterator, class _Compare>
2523inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2524_ForwardIterator
2525min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2526{
2527    if (__first != __last)
2528    {
2529        _ForwardIterator __i = __first;
2530        while (++__i != __last)
2531            if (__comp(*__i, *__first))
2532                __first = __i;
2533    }
2534    return __first;
2535}
2536
2537template <class _ForwardIterator>
2538inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2539_ForwardIterator
2540min_element(_ForwardIterator __first, _ForwardIterator __last)
2541{
2542    return _VSTD::min_element(__first, __last,
2543              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2544}
2545
2546// min
2547
2548template <class _Tp, class _Compare>
2549inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2550const _Tp&
2551min(const _Tp& __a, const _Tp& __b, _Compare __comp)
2552{
2553    return __comp(__b, __a) ? __b : __a;
2554}
2555
2556template <class _Tp>
2557inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2558const _Tp&
2559min(const _Tp& __a, const _Tp& __b)
2560{
2561    return _VSTD::min(__a, __b, __less<_Tp>());
2562}
2563
2564#ifndef _LIBCPP_CXX03_LANG
2565
2566template<class _Tp, class _Compare>
2567inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2568_Tp
2569min(initializer_list<_Tp> __t, _Compare __comp)
2570{
2571    return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
2572}
2573
2574template<class _Tp>
2575inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2576_Tp
2577min(initializer_list<_Tp> __t)
2578{
2579    return *_VSTD::min_element(__t.begin(), __t.end(), __less<_Tp>());
2580}
2581
2582#endif  // _LIBCPP_CXX03_LANG
2583
2584// max_element
2585
2586template <class _ForwardIterator, class _Compare>
2587inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2588_ForwardIterator
2589max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2590{
2591    if (__first != __last)
2592    {
2593        _ForwardIterator __i = __first;
2594        while (++__i != __last)
2595            if (__comp(*__first, *__i))
2596                __first = __i;
2597    }
2598    return __first;
2599}
2600
2601
2602template <class _ForwardIterator>
2603inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2604_ForwardIterator
2605max_element(_ForwardIterator __first, _ForwardIterator __last)
2606{
2607    return _VSTD::max_element(__first, __last,
2608              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2609}
2610
2611// max
2612
2613template <class _Tp, class _Compare>
2614inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2615const _Tp&
2616max(const _Tp& __a, const _Tp& __b, _Compare __comp)
2617{
2618    return __comp(__a, __b) ? __b : __a;
2619}
2620
2621template <class _Tp>
2622inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2623const _Tp&
2624max(const _Tp& __a, const _Tp& __b)
2625{
2626    return _VSTD::max(__a, __b, __less<_Tp>());
2627}
2628
2629#ifndef _LIBCPP_CXX03_LANG
2630
2631template<class _Tp, class _Compare>
2632inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2633_Tp
2634max(initializer_list<_Tp> __t, _Compare __comp)
2635{
2636    return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
2637}
2638
2639template<class _Tp>
2640inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2641_Tp
2642max(initializer_list<_Tp> __t)
2643{
2644    return *_VSTD::max_element(__t.begin(), __t.end(), __less<_Tp>());
2645}
2646
2647#endif  // _LIBCPP_CXX03_LANG
2648
2649#if _LIBCPP_STD_VER > 14
2650// clamp
2651template<class _Tp, class _Compare>
2652inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2653const _Tp&
2654clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
2655{
2656    _LIBCPP_ASSERT(!__comp(__hi, __lo), "Bad bounds passed to std::clamp");
2657    return __comp(__v, __lo) ? __lo : __comp(__hi, __v) ? __hi : __v;
2658
2659}
2660
2661template<class _Tp>
2662inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2663const _Tp&
2664clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi)
2665{
2666    return _VSTD::clamp(__v, __lo, __hi, __less<_Tp>());
2667}
2668#endif
2669
2670// minmax_element
2671
2672template <class _ForwardIterator, class _Compare>
2673_LIBCPP_CONSTEXPR_AFTER_CXX11
2674std::pair<_ForwardIterator, _ForwardIterator>
2675minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2676{
2677  std::pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
2678  if (__first != __last)
2679  {
2680      if (++__first != __last)
2681      {
2682          if (__comp(*__first, *__result.first))
2683              __result.first = __first;
2684          else
2685              __result.second = __first;
2686          while (++__first != __last)
2687          {
2688              _ForwardIterator __i = __first;
2689              if (++__first == __last)
2690              {
2691                  if (__comp(*__i, *__result.first))
2692                      __result.first = __i;
2693                  else if (!__comp(*__i, *__result.second))
2694                      __result.second = __i;
2695                  break;
2696              }
2697              else
2698              {
2699                  if (__comp(*__first, *__i))
2700                  {
2701                      if (__comp(*__first, *__result.first))
2702                          __result.first = __first;
2703                      if (!__comp(*__i, *__result.second))
2704                          __result.second = __i;
2705                  }
2706                  else
2707                  {
2708                      if (__comp(*__i, *__result.first))
2709                          __result.first = __i;
2710                      if (!__comp(*__first, *__result.second))
2711                          __result.second = __first;
2712                  }
2713              }
2714          }
2715      }
2716  }
2717  return __result;
2718}
2719
2720template <class _ForwardIterator>
2721inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2722std::pair<_ForwardIterator, _ForwardIterator>
2723minmax_element(_ForwardIterator __first, _ForwardIterator __last)
2724{
2725    return _VSTD::minmax_element(__first, __last,
2726              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2727}
2728
2729// minmax
2730
2731template<class _Tp, class _Compare>
2732inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2733pair<const _Tp&, const _Tp&>
2734minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
2735{
2736    return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a) :
2737                              pair<const _Tp&, const _Tp&>(__a, __b);
2738}
2739
2740template<class _Tp>
2741inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2742pair<const _Tp&, const _Tp&>
2743minmax(const _Tp& __a, const _Tp& __b)
2744{
2745    return _VSTD::minmax(__a, __b, __less<_Tp>());
2746}
2747
2748#ifndef _LIBCPP_CXX03_LANG
2749
2750template<class _Tp, class _Compare>
2751inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2752pair<_Tp, _Tp>
2753minmax(initializer_list<_Tp> __t, _Compare __comp)
2754{
2755    typedef typename initializer_list<_Tp>::const_iterator _Iter;
2756    _Iter __first = __t.begin();
2757    _Iter __last  = __t.end();
2758    std::pair<_Tp, _Tp> __result(*__first, *__first);
2759
2760    ++__first;
2761    if (__t.size() % 2 == 0)
2762    {
2763        if (__comp(*__first,  __result.first))
2764            __result.first  = *__first;
2765        else
2766            __result.second = *__first;
2767        ++__first;
2768    }
2769
2770    while (__first != __last)
2771    {
2772        _Tp __prev = *__first++;
2773        if (__comp(*__first, __prev)) {
2774            if ( __comp(*__first, __result.first)) __result.first  = *__first;
2775            if (!__comp(__prev, __result.second))  __result.second = __prev;
2776            }
2777        else {
2778            if ( __comp(__prev, __result.first))    __result.first  = __prev;
2779            if (!__comp(*__first, __result.second)) __result.second = *__first;
2780            }
2781
2782        __first++;
2783    }
2784    return __result;
2785}
2786
2787template<class _Tp>
2788inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2789pair<_Tp, _Tp>
2790minmax(initializer_list<_Tp> __t)
2791{
2792    return _VSTD::minmax(__t, __less<_Tp>());
2793}
2794
2795#endif  // _LIBCPP_CXX03_LANG
2796
2797// random_shuffle
2798
2799// __independent_bits_engine
2800
2801template <unsigned long long _Xp, size_t _Rp>
2802struct __log2_imp
2803{
2804    static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
2805                                           : __log2_imp<_Xp, _Rp - 1>::value;
2806};
2807
2808template <unsigned long long _Xp>
2809struct __log2_imp<_Xp, 0>
2810{
2811    static const size_t value = 0;
2812};
2813
2814template <size_t _Rp>
2815struct __log2_imp<0, _Rp>
2816{
2817    static const size_t value = _Rp + 1;
2818};
2819
2820template <class _UIntType, _UIntType _Xp>
2821struct __log2
2822{
2823    static const size_t value = __log2_imp<_Xp,
2824                                         sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
2825};
2826
2827template<class _Engine, class _UIntType>
2828class __independent_bits_engine
2829{
2830public:
2831    // types
2832    typedef _UIntType result_type;
2833
2834private:
2835    typedef typename _Engine::result_type _Engine_result_type;
2836    typedef typename conditional
2837        <
2838            sizeof(_Engine_result_type) <= sizeof(result_type),
2839                result_type,
2840                _Engine_result_type
2841        >::type _Working_result_type;
2842
2843    _Engine& __e_;
2844    size_t __w_;
2845    size_t __w0_;
2846    size_t __n_;
2847    size_t __n0_;
2848    _Working_result_type __y0_;
2849    _Working_result_type __y1_;
2850    _Engine_result_type __mask0_;
2851    _Engine_result_type __mask1_;
2852
2853#ifdef _LIBCPP_CXX03_LANG
2854    static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
2855                                          + _Working_result_type(1);
2856#else
2857    static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
2858                                                      + _Working_result_type(1);
2859#endif
2860    static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
2861    static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
2862    static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
2863
2864public:
2865    // constructors and seeding functions
2866    __independent_bits_engine(_Engine& __e, size_t __w);
2867
2868    // generating functions
2869    result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
2870
2871private:
2872    result_type __eval(false_type);
2873    result_type __eval(true_type);
2874};
2875
2876template<class _Engine, class _UIntType>
2877__independent_bits_engine<_Engine, _UIntType>
2878    ::__independent_bits_engine(_Engine& __e, size_t __w)
2879        : __e_(__e),
2880          __w_(__w)
2881{
2882    __n_ = __w_ / __m + (__w_ % __m != 0);
2883    __w0_ = __w_ / __n_;
2884    if (_Rp == 0)
2885        __y0_ = _Rp;
2886    else if (__w0_ < _WDt)
2887        __y0_ = (_Rp >> __w0_) << __w0_;
2888    else
2889        __y0_ = 0;
2890    if (_Rp - __y0_ > __y0_ / __n_)
2891    {
2892        ++__n_;
2893        __w0_ = __w_ / __n_;
2894        if (__w0_ < _WDt)
2895            __y0_ = (_Rp >> __w0_) << __w0_;
2896        else
2897            __y0_ = 0;
2898    }
2899    __n0_ = __n_ - __w_ % __n_;
2900    if (__w0_ < _WDt - 1)
2901        __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
2902    else
2903        __y1_ = 0;
2904    __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
2905                          _Engine_result_type(0);
2906    __mask1_ = __w0_ < _EDt - 1 ?
2907                               _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) :
2908                               _Engine_result_type(~0);
2909}
2910
2911template<class _Engine, class _UIntType>
2912inline
2913_UIntType
2914__independent_bits_engine<_Engine, _UIntType>::__eval(false_type)
2915{
2916    return static_cast<result_type>(__e_() & __mask0_);
2917}
2918
2919template<class _Engine, class _UIntType>
2920_UIntType
2921__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
2922{
2923    const size_t _WRt = numeric_limits<result_type>::digits;
2924    result_type _Sp = 0;
2925    for (size_t __k = 0; __k < __n0_; ++__k)
2926    {
2927        _Engine_result_type __u;
2928        do
2929        {
2930            __u = __e_() - _Engine::min();
2931        } while (__u >= __y0_);
2932        if (__w0_ < _WRt)
2933            _Sp <<= __w0_;
2934        else
2935            _Sp = 0;
2936        _Sp += __u & __mask0_;
2937    }
2938    for (size_t __k = __n0_; __k < __n_; ++__k)
2939    {
2940        _Engine_result_type __u;
2941        do
2942        {
2943            __u = __e_() - _Engine::min();
2944        } while (__u >= __y1_);
2945        if (__w0_ < _WRt - 1)
2946            _Sp <<= __w0_ + 1;
2947        else
2948            _Sp = 0;
2949        _Sp += __u & __mask1_;
2950    }
2951    return _Sp;
2952}
2953
2954// uniform_int_distribution
2955
2956template<class _IntType = int>
2957class uniform_int_distribution
2958{
2959public:
2960    // types
2961    typedef _IntType result_type;
2962
2963    class param_type
2964    {
2965        result_type __a_;
2966        result_type __b_;
2967    public:
2968        typedef uniform_int_distribution distribution_type;
2969
2970        explicit param_type(result_type __a = 0,
2971                            result_type __b = numeric_limits<result_type>::max())
2972            : __a_(__a), __b_(__b) {}
2973
2974        result_type a() const {return __a_;}
2975        result_type b() const {return __b_;}
2976
2977        friend bool operator==(const param_type& __x, const param_type& __y)
2978            {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
2979        friend bool operator!=(const param_type& __x, const param_type& __y)
2980            {return !(__x == __y);}
2981    };
2982
2983private:
2984    param_type __p_;
2985
2986public:
2987    // constructors and reset functions
2988    explicit uniform_int_distribution(result_type __a = 0,
2989                                      result_type __b = numeric_limits<result_type>::max())
2990        : __p_(param_type(__a, __b)) {}
2991    explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
2992    void reset() {}
2993
2994    // generating functions
2995    template<class _URNG> result_type operator()(_URNG& __g)
2996        {return (*this)(__g, __p_);}
2997    template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
2998
2999    // property functions
3000    result_type a() const {return __p_.a();}
3001    result_type b() const {return __p_.b();}
3002
3003    param_type param() const {return __p_;}
3004    void param(const param_type& __p) {__p_ = __p;}
3005
3006    result_type min() const {return a();}
3007    result_type max() const {return b();}
3008
3009    friend bool operator==(const uniform_int_distribution& __x,
3010                           const uniform_int_distribution& __y)
3011        {return __x.__p_ == __y.__p_;}
3012    friend bool operator!=(const uniform_int_distribution& __x,
3013                           const uniform_int_distribution& __y)
3014            {return !(__x == __y);}
3015};
3016
3017template<class _IntType>
3018template<class _URNG>
3019typename uniform_int_distribution<_IntType>::result_type
3020uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
3021{
3022    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
3023                                            uint32_t, uint64_t>::type _UIntType;
3024    const _UIntType _Rp = __p.b() - __p.a() + _UIntType(1);
3025    if (_Rp == 1)
3026        return __p.a();
3027    const size_t _Dt = numeric_limits<_UIntType>::digits;
3028    typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
3029    if (_Rp == 0)
3030        return static_cast<result_type>(_Eng(__g, _Dt)());
3031    size_t __w = _Dt - __clz(_Rp) - 1;
3032    if ((_Rp & (std::numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
3033        ++__w;
3034    _Eng __e(__g, __w);
3035    _UIntType __u;
3036    do
3037    {
3038        __u = __e();
3039    } while (__u >= _Rp);
3040    return static_cast<result_type>(__u + __p.a());
3041}
3042
3043#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) \
3044  || defined(_LIBCPP_BUILDING_LIBRARY)
3045class _LIBCPP_TYPE_VIS __rs_default;
3046
3047_LIBCPP_FUNC_VIS __rs_default __rs_get();
3048
3049class _LIBCPP_TYPE_VIS __rs_default
3050{
3051    static unsigned __c_;
3052
3053    __rs_default();
3054public:
3055    typedef uint_fast32_t result_type;
3056
3057    static const result_type _Min = 0;
3058    static const result_type _Max = 0xFFFFFFFF;
3059
3060    __rs_default(const __rs_default&);
3061    ~__rs_default();
3062
3063    result_type operator()();
3064
3065    static _LIBCPP_CONSTEXPR result_type min() {return _Min;}
3066    static _LIBCPP_CONSTEXPR result_type max() {return _Max;}
3067
3068    friend _LIBCPP_FUNC_VIS __rs_default __rs_get();
3069};
3070
3071_LIBCPP_FUNC_VIS __rs_default __rs_get();
3072
3073template <class _RandomAccessIterator>
3074void
3075random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
3076{
3077    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3078    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3079    typedef typename _Dp::param_type _Pp;
3080    difference_type __d = __last - __first;
3081    if (__d > 1)
3082    {
3083        _Dp __uid;
3084        __rs_default __g = __rs_get();
3085        for (--__last, --__d; __first < __last; ++__first, --__d)
3086        {
3087            difference_type __i = __uid(__g, _Pp(0, __d));
3088            if (__i != difference_type(0))
3089                swap(*__first, *(__first + __i));
3090        }
3091    }
3092}
3093
3094template <class _RandomAccessIterator, class _RandomNumberGenerator>
3095void
3096random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3097#ifndef _LIBCPP_CXX03_LANG
3098               _RandomNumberGenerator&& __rand)
3099#else
3100               _RandomNumberGenerator& __rand)
3101#endif
3102{
3103    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3104    difference_type __d = __last - __first;
3105    if (__d > 1)
3106    {
3107        for (--__last; __first < __last; ++__first, --__d)
3108        {
3109            difference_type __i = __rand(__d);
3110            swap(*__first, *(__first + __i));
3111        }
3112    }
3113}
3114#endif
3115
3116template <class _PopulationIterator, class _SampleIterator, class _Distance,
3117          class _UniformRandomNumberGenerator>
3118_LIBCPP_INLINE_VISIBILITY
3119_SampleIterator __sample(_PopulationIterator __first,
3120                         _PopulationIterator __last, _SampleIterator __output_iter,
3121                         _Distance __n,
3122                         _UniformRandomNumberGenerator & __g,
3123                         input_iterator_tag) {
3124
3125  _Distance __k = 0;
3126  for (; __first != __last && __k < __n; ++__first, (void)++__k)
3127    __output_iter[__k] = *__first;
3128  _Distance __sz = __k;
3129  for (; __first != __last; ++__first, (void)++__k) {
3130    _Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);
3131    if (__r < __sz)
3132      __output_iter[__r] = *__first;
3133  }
3134  return __output_iter + _VSTD::min(__n, __k);
3135}
3136
3137template <class _PopulationIterator, class _SampleIterator, class _Distance,
3138          class _UniformRandomNumberGenerator>
3139_LIBCPP_INLINE_VISIBILITY
3140_SampleIterator __sample(_PopulationIterator __first,
3141                         _PopulationIterator __last, _SampleIterator __output_iter,
3142                         _Distance __n,
3143                         _UniformRandomNumberGenerator& __g,
3144                         forward_iterator_tag) {
3145  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
3146  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
3147    _Distance __r =
3148        _VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
3149    if (__r < __n) {
3150      *__output_iter++ = *__first;
3151      --__n;
3152    }
3153  }
3154  return __output_iter;
3155}
3156
3157template <class _PopulationIterator, class _SampleIterator, class _Distance,
3158          class _UniformRandomNumberGenerator>
3159_LIBCPP_INLINE_VISIBILITY
3160_SampleIterator __sample(_PopulationIterator __first,
3161                         _PopulationIterator __last, _SampleIterator __output_iter,
3162                         _Distance __n, _UniformRandomNumberGenerator& __g) {
3163  typedef typename iterator_traits<_PopulationIterator>::iterator_category
3164        _PopCategory;
3165  typedef typename iterator_traits<_PopulationIterator>::difference_type
3166        _Difference;
3167  static_assert(__is_forward_iterator<_PopulationIterator>::value ||
3168                __is_random_access_iterator<_SampleIterator>::value,
3169                "SampleIterator must meet the requirements of RandomAccessIterator");
3170  typedef typename common_type<_Distance, _Difference>::type _CommonType;
3171  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
3172  return _VSTD::__sample(
3173      __first, __last, __output_iter, _CommonType(__n),
3174      __g, _PopCategory());
3175}
3176
3177#if _LIBCPP_STD_VER > 14
3178template <class _PopulationIterator, class _SampleIterator, class _Distance,
3179          class _UniformRandomNumberGenerator>
3180inline _LIBCPP_INLINE_VISIBILITY
3181_SampleIterator sample(_PopulationIterator __first,
3182                       _PopulationIterator __last, _SampleIterator __output_iter,
3183                       _Distance __n, _UniformRandomNumberGenerator&& __g) {
3184    return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
3185}
3186#endif // _LIBCPP_STD_VER > 14
3187
3188template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
3189    void shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3190#ifndef _LIBCPP_CXX03_LANG
3191                 _UniformRandomNumberGenerator&& __g)
3192#else
3193                 _UniformRandomNumberGenerator& __g)
3194#endif
3195{
3196    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3197    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3198    typedef typename _Dp::param_type _Pp;
3199    difference_type __d = __last - __first;
3200    if (__d > 1)
3201    {
3202        _Dp __uid;
3203        for (--__last, --__d; __first < __last; ++__first, --__d)
3204        {
3205            difference_type __i = __uid(__g, _Pp(0, __d));
3206            if (__i != difference_type(0))
3207                swap(*__first, *(__first + __i));
3208        }
3209    }
3210}
3211
3212template <class _InputIterator, class _Predicate>
3213_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
3214is_partitioned(_InputIterator __first, _InputIterator __last, _Predicate __pred)
3215{
3216    for (; __first != __last; ++__first)
3217        if (!__pred(*__first))
3218            break;
3219    if ( __first == __last )
3220        return true;
3221    ++__first;
3222    for (; __first != __last; ++__first)
3223        if (__pred(*__first))
3224            return false;
3225    return true;
3226}
3227
3228// partition
3229
3230template <class _Predicate, class _ForwardIterator>
3231_ForwardIterator
3232__partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag)
3233{
3234    while (true)
3235    {
3236        if (__first == __last)
3237            return __first;
3238        if (!__pred(*__first))
3239            break;
3240        ++__first;
3241    }
3242    for (_ForwardIterator __p = __first; ++__p != __last;)
3243    {
3244        if (__pred(*__p))
3245        {
3246            swap(*__first, *__p);
3247            ++__first;
3248        }
3249    }
3250    return __first;
3251}
3252
3253template <class _Predicate, class _BidirectionalIterator>
3254_BidirectionalIterator
3255__partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3256            bidirectional_iterator_tag)
3257{
3258    while (true)
3259    {
3260        while (true)
3261        {
3262            if (__first == __last)
3263                return __first;
3264            if (!__pred(*__first))
3265                break;
3266            ++__first;
3267        }
3268        do
3269        {
3270            if (__first == --__last)
3271                return __first;
3272        } while (!__pred(*__last));
3273        swap(*__first, *__last);
3274        ++__first;
3275    }
3276}
3277
3278template <class _ForwardIterator, class _Predicate>
3279inline _LIBCPP_INLINE_VISIBILITY
3280_ForwardIterator
3281partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3282{
3283    return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type>
3284                            (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3285}
3286
3287// partition_copy
3288
3289template <class _InputIterator, class _OutputIterator1,
3290          class _OutputIterator2, class _Predicate>
3291pair<_OutputIterator1, _OutputIterator2>
3292partition_copy(_InputIterator __first, _InputIterator __last,
3293               _OutputIterator1 __out_true, _OutputIterator2 __out_false,
3294               _Predicate __pred)
3295{
3296    for (; __first != __last; ++__first)
3297    {
3298        if (__pred(*__first))
3299        {
3300            *__out_true = *__first;
3301            ++__out_true;
3302        }
3303        else
3304        {
3305            *__out_false = *__first;
3306            ++__out_false;
3307        }
3308    }
3309    return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
3310}
3311
3312// partition_point
3313
3314template<class _ForwardIterator, class _Predicate>
3315_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3316partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3317{
3318    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3319    difference_type __len = _VSTD::distance(__first, __last);
3320    while (__len != 0)
3321    {
3322        difference_type __l2 = __len / 2;
3323        _ForwardIterator __m = __first;
3324        _VSTD::advance(__m, __l2);
3325        if (__pred(*__m))
3326        {
3327            __first = ++__m;
3328            __len -= __l2 + 1;
3329        }
3330        else
3331            __len = __l2;
3332    }
3333    return __first;
3334}
3335
3336// stable_partition
3337
3338template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair>
3339_ForwardIterator
3340__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3341                   _Distance __len, _Pair __p, forward_iterator_tag __fit)
3342{
3343    // *__first is known to be false
3344    // __len >= 1
3345    if (__len == 1)
3346        return __first;
3347    if (__len == 2)
3348    {
3349        _ForwardIterator __m = __first;
3350        if (__pred(*++__m))
3351        {
3352            swap(*__first, *__m);
3353            return __m;
3354        }
3355        return __first;
3356    }
3357    if (__len <= __p.second)
3358    {   // The buffer is big enough to use
3359        typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3360        __destruct_n __d(0);
3361        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3362        // Move the falses into the temporary buffer, and the trues to the front of the line
3363        // Update __first to always point to the end of the trues
3364        value_type* __t = __p.first;
3365        ::new(__t) value_type(_VSTD::move(*__first));
3366        __d.__incr((value_type*)0);
3367        ++__t;
3368        _ForwardIterator __i = __first;
3369        while (++__i != __last)
3370        {
3371            if (__pred(*__i))
3372            {
3373                *__first = _VSTD::move(*__i);
3374                ++__first;
3375            }
3376            else
3377            {
3378                ::new(__t) value_type(_VSTD::move(*__i));
3379                __d.__incr((value_type*)0);
3380                ++__t;
3381            }
3382        }
3383        // All trues now at start of range, all falses in buffer
3384        // Move falses back into range, but don't mess up __first which points to first false
3385        __i = __first;
3386        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3387            *__i = _VSTD::move(*__t2);
3388        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3389        return __first;
3390    }
3391    // Else not enough buffer, do in place
3392    // __len >= 3
3393    _ForwardIterator __m = __first;
3394    _Distance __len2 = __len / 2;  // __len2 >= 2
3395    _VSTD::advance(__m, __len2);
3396    // recurse on [__first, __m), *__first know to be false
3397    // F?????????????????
3398    // f       m         l
3399    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3400    _ForwardIterator __first_false = __stable_partition<_PredRef>(__first, __m, __pred, __len2, __p, __fit);
3401    // TTTFFFFF??????????
3402    // f  ff   m         l
3403    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3404    _ForwardIterator __m1 = __m;
3405    _ForwardIterator __second_false = __last;
3406    _Distance __len_half = __len - __len2;
3407    while (__pred(*__m1))
3408    {
3409        if (++__m1 == __last)
3410            goto __second_half_done;
3411        --__len_half;
3412    }
3413    // TTTFFFFFTTTF??????
3414    // f  ff   m  m1     l
3415    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __fit);
3416__second_half_done:
3417    // TTTFFFFFTTTTTFFFFF
3418    // f  ff   m    sf   l
3419    return _VSTD::rotate(__first_false, __m, __second_false);
3420    // TTTTTTTTFFFFFFFFFF
3421    //         |
3422}
3423
3424struct __return_temporary_buffer
3425{
3426    template <class _Tp>
3427    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
3428};
3429
3430template <class _Predicate, class _ForwardIterator>
3431_ForwardIterator
3432__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3433                   forward_iterator_tag)
3434{
3435    const unsigned __alloc_limit = 3;  // might want to make this a function of trivial assignment
3436    // Either prove all true and return __first or point to first false
3437    while (true)
3438    {
3439        if (__first == __last)
3440            return __first;
3441        if (!__pred(*__first))
3442            break;
3443        ++__first;
3444    }
3445    // We now have a reduced range [__first, __last)
3446    // *__first is known to be false
3447    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3448    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3449    difference_type __len = _VSTD::distance(__first, __last);
3450    pair<value_type*, ptrdiff_t> __p(0, 0);
3451    unique_ptr<value_type, __return_temporary_buffer> __h;
3452    if (__len >= __alloc_limit)
3453    {
3454        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3455        __h.reset(__p.first);
3456    }
3457    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3458                             (__first, __last, __pred, __len, __p, forward_iterator_tag());
3459}
3460
3461template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair>
3462_BidirectionalIterator
3463__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3464                   _Distance __len, _Pair __p, bidirectional_iterator_tag __bit)
3465{
3466    // *__first is known to be false
3467    // *__last is known to be true
3468    // __len >= 2
3469    if (__len == 2)
3470    {
3471        swap(*__first, *__last);
3472        return __last;
3473    }
3474    if (__len == 3)
3475    {
3476        _BidirectionalIterator __m = __first;
3477        if (__pred(*++__m))
3478        {
3479            swap(*__first, *__m);
3480            swap(*__m, *__last);
3481            return __last;
3482        }
3483        swap(*__m, *__last);
3484        swap(*__first, *__m);
3485        return __m;
3486    }
3487    if (__len <= __p.second)
3488    {   // The buffer is big enough to use
3489        typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3490        __destruct_n __d(0);
3491        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3492        // Move the falses into the temporary buffer, and the trues to the front of the line
3493        // Update __first to always point to the end of the trues
3494        value_type* __t = __p.first;
3495        ::new(__t) value_type(_VSTD::move(*__first));
3496        __d.__incr((value_type*)0);
3497        ++__t;
3498        _BidirectionalIterator __i = __first;
3499        while (++__i != __last)
3500        {
3501            if (__pred(*__i))
3502            {
3503                *__first = _VSTD::move(*__i);
3504                ++__first;
3505            }
3506            else
3507            {
3508                ::new(__t) value_type(_VSTD::move(*__i));
3509                __d.__incr((value_type*)0);
3510                ++__t;
3511            }
3512        }
3513        // move *__last, known to be true
3514        *__first = _VSTD::move(*__i);
3515        __i = ++__first;
3516        // All trues now at start of range, all falses in buffer
3517        // Move falses back into range, but don't mess up __first which points to first false
3518        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3519            *__i = _VSTD::move(*__t2);
3520        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3521        return __first;
3522    }
3523    // Else not enough buffer, do in place
3524    // __len >= 4
3525    _BidirectionalIterator __m = __first;
3526    _Distance __len2 = __len / 2;  // __len2 >= 2
3527    _VSTD::advance(__m, __len2);
3528    // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false
3529    // F????????????????T
3530    // f       m        l
3531    _BidirectionalIterator __m1 = __m;
3532    _BidirectionalIterator __first_false = __first;
3533    _Distance __len_half = __len2;
3534    while (!__pred(*--__m1))
3535    {
3536        if (__m1 == __first)
3537            goto __first_half_done;
3538        --__len_half;
3539    }
3540    // F???TFFF?????????T
3541    // f   m1  m        l
3542    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3543    __first_false = __stable_partition<_PredRef>(__first, __m1, __pred, __len_half, __p, __bit);
3544__first_half_done:
3545    // TTTFFFFF?????????T
3546    // f  ff   m        l
3547    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3548    __m1 = __m;
3549    _BidirectionalIterator __second_false = __last;
3550    ++__second_false;
3551    __len_half = __len - __len2;
3552    while (__pred(*__m1))
3553    {
3554        if (++__m1 == __last)
3555            goto __second_half_done;
3556        --__len_half;
3557    }
3558    // TTTFFFFFTTTF?????T
3559    // f  ff   m  m1    l
3560    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __bit);
3561__second_half_done:
3562    // TTTFFFFFTTTTTFFFFF
3563    // f  ff   m    sf  l
3564    return _VSTD::rotate(__first_false, __m, __second_false);
3565    // TTTTTTTTFFFFFFFFFF
3566    //         |
3567}
3568
3569template <class _Predicate, class _BidirectionalIterator>
3570_BidirectionalIterator
3571__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3572                   bidirectional_iterator_tag)
3573{
3574    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
3575    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3576    const difference_type __alloc_limit = 4;  // might want to make this a function of trivial assignment
3577    // Either prove all true and return __first or point to first false
3578    while (true)
3579    {
3580        if (__first == __last)
3581            return __first;
3582        if (!__pred(*__first))
3583            break;
3584        ++__first;
3585    }
3586    // __first points to first false, everything prior to __first is already set.
3587    // Either prove [__first, __last) is all false and return __first, or point __last to last true
3588    do
3589    {
3590        if (__first == --__last)
3591            return __first;
3592    } while (!__pred(*__last));
3593    // We now have a reduced range [__first, __last]
3594    // *__first is known to be false
3595    // *__last is known to be true
3596    // __len >= 2
3597    difference_type __len = _VSTD::distance(__first, __last) + 1;
3598    pair<value_type*, ptrdiff_t> __p(0, 0);
3599    unique_ptr<value_type, __return_temporary_buffer> __h;
3600    if (__len >= __alloc_limit)
3601    {
3602        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3603        __h.reset(__p.first);
3604    }
3605    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3606                             (__first, __last, __pred, __len, __p, bidirectional_iterator_tag());
3607}
3608
3609template <class _ForwardIterator, class _Predicate>
3610inline _LIBCPP_INLINE_VISIBILITY
3611_ForwardIterator
3612stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3613{
3614    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3615                             (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3616}
3617
3618// is_sorted_until
3619
3620template <class _ForwardIterator, class _Compare>
3621_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3622is_sorted_until(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3623{
3624    if (__first != __last)
3625    {
3626        _ForwardIterator __i = __first;
3627        while (++__i != __last)
3628        {
3629            if (__comp(*__i, *__first))
3630                return __i;
3631            __first = __i;
3632        }
3633    }
3634    return __last;
3635}
3636
3637template<class _ForwardIterator>
3638inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3639_ForwardIterator
3640is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
3641{
3642    return _VSTD::is_sorted_until(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3643}
3644
3645// is_sorted
3646
3647template <class _ForwardIterator, class _Compare>
3648inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3649bool
3650is_sorted(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3651{
3652    return _VSTD::is_sorted_until(__first, __last, __comp) == __last;
3653}
3654
3655template<class _ForwardIterator>
3656inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3657bool
3658is_sorted(_ForwardIterator __first, _ForwardIterator __last)
3659{
3660    return _VSTD::is_sorted(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3661}
3662
3663// sort
3664
3665// stable, 2-3 compares, 0-2 swaps
3666
3667template <class _Compare, class _ForwardIterator>
3668unsigned
3669__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
3670{
3671    unsigned __r = 0;
3672    if (!__c(*__y, *__x))          // if x <= y
3673    {
3674        if (!__c(*__z, *__y))      // if y <= z
3675            return __r;            // x <= y && y <= z
3676                                   // x <= y && y > z
3677        swap(*__y, *__z);          // x <= z && y < z
3678        __r = 1;
3679        if (__c(*__y, *__x))       // if x > y
3680        {
3681            swap(*__x, *__y);      // x < y && y <= z
3682            __r = 2;
3683        }
3684        return __r;                // x <= y && y < z
3685    }
3686    if (__c(*__z, *__y))           // x > y, if y > z
3687    {
3688        swap(*__x, *__z);          // x < y && y < z
3689        __r = 1;
3690        return __r;
3691    }
3692    swap(*__x, *__y);              // x > y && y <= z
3693    __r = 1;                       // x < y && x <= z
3694    if (__c(*__z, *__y))           // if y > z
3695    {
3696        swap(*__y, *__z);          // x <= y && y < z
3697        __r = 2;
3698    }
3699    return __r;
3700}                                  // x <= y && y <= z
3701
3702// stable, 3-6 compares, 0-5 swaps
3703
3704template <class _Compare, class _ForwardIterator>
3705unsigned
3706__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3707            _ForwardIterator __x4, _Compare __c)
3708{
3709    unsigned __r = __sort3<_Compare>(__x1, __x2, __x3, __c);
3710    if (__c(*__x4, *__x3))
3711    {
3712        swap(*__x3, *__x4);
3713        ++__r;
3714        if (__c(*__x3, *__x2))
3715        {
3716            swap(*__x2, *__x3);
3717            ++__r;
3718            if (__c(*__x2, *__x1))
3719            {
3720                swap(*__x1, *__x2);
3721                ++__r;
3722            }
3723        }
3724    }
3725    return __r;
3726}
3727
3728// stable, 4-10 compares, 0-9 swaps
3729
3730template <class _Compare, class _ForwardIterator>
3731unsigned
3732__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3733            _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
3734{
3735    unsigned __r = __sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
3736    if (__c(*__x5, *__x4))
3737    {
3738        swap(*__x4, *__x5);
3739        ++__r;
3740        if (__c(*__x4, *__x3))
3741        {
3742            swap(*__x3, *__x4);
3743            ++__r;
3744            if (__c(*__x3, *__x2))
3745            {
3746                swap(*__x2, *__x3);
3747                ++__r;
3748                if (__c(*__x2, *__x1))
3749                {
3750                    swap(*__x1, *__x2);
3751                    ++__r;
3752                }
3753            }
3754        }
3755    }
3756    return __r;
3757}
3758
3759// Assumes size > 0
3760template <class _Compare, class _BirdirectionalIterator>
3761void
3762__selection_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3763{
3764    _BirdirectionalIterator __lm1 = __last;
3765    for (--__lm1; __first != __lm1; ++__first)
3766    {
3767        _BirdirectionalIterator __i = _VSTD::min_element<_BirdirectionalIterator,
3768                                                        typename add_lvalue_reference<_Compare>::type>
3769                                                       (__first, __last, __comp);
3770        if (__i != __first)
3771            swap(*__first, *__i);
3772    }
3773}
3774
3775template <class _Compare, class _BirdirectionalIterator>
3776void
3777__insertion_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3778{
3779    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3780    if (__first != __last)
3781    {
3782        _BirdirectionalIterator __i = __first;
3783        for (++__i; __i != __last; ++__i)
3784        {
3785            _BirdirectionalIterator __j = __i;
3786            value_type __t(_VSTD::move(*__j));
3787            for (_BirdirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
3788                *__j = _VSTD::move(*__k);
3789            *__j = _VSTD::move(__t);
3790        }
3791    }
3792}
3793
3794template <class _Compare, class _RandomAccessIterator>
3795void
3796__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3797{
3798    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3799    _RandomAccessIterator __j = __first+2;
3800    __sort3<_Compare>(__first, __first+1, __j, __comp);
3801    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3802    {
3803        if (__comp(*__i, *__j))
3804        {
3805            value_type __t(_VSTD::move(*__i));
3806            _RandomAccessIterator __k = __j;
3807            __j = __i;
3808            do
3809            {
3810                *__j = _VSTD::move(*__k);
3811                __j = __k;
3812            } while (__j != __first && __comp(__t, *--__k));
3813            *__j = _VSTD::move(__t);
3814        }
3815        __j = __i;
3816    }
3817}
3818
3819template <class _Compare, class _RandomAccessIterator>
3820bool
3821__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3822{
3823    switch (__last - __first)
3824    {
3825    case 0:
3826    case 1:
3827        return true;
3828    case 2:
3829        if (__comp(*--__last, *__first))
3830            swap(*__first, *__last);
3831        return true;
3832    case 3:
3833        _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3834        return true;
3835    case 4:
3836        _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3837        return true;
3838    case 5:
3839        _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3840        return true;
3841    }
3842    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3843    _RandomAccessIterator __j = __first+2;
3844    __sort3<_Compare>(__first, __first+1, __j, __comp);
3845    const unsigned __limit = 8;
3846    unsigned __count = 0;
3847    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3848    {
3849        if (__comp(*__i, *__j))
3850        {
3851            value_type __t(_VSTD::move(*__i));
3852            _RandomAccessIterator __k = __j;
3853            __j = __i;
3854            do
3855            {
3856                *__j = _VSTD::move(*__k);
3857                __j = __k;
3858            } while (__j != __first && __comp(__t, *--__k));
3859            *__j = _VSTD::move(__t);
3860            if (++__count == __limit)
3861                return ++__i == __last;
3862        }
3863        __j = __i;
3864    }
3865    return true;
3866}
3867
3868template <class _Compare, class _BirdirectionalIterator>
3869void
3870__insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator __last1,
3871                      typename iterator_traits<_BirdirectionalIterator>::value_type* __first2, _Compare __comp)
3872{
3873    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3874    if (__first1 != __last1)
3875    {
3876        __destruct_n __d(0);
3877        unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
3878        value_type* __last2 = __first2;
3879        ::new(__last2) value_type(_VSTD::move(*__first1));
3880        __d.__incr((value_type*)0);
3881        for (++__last2; ++__first1 != __last1; ++__last2)
3882        {
3883            value_type* __j2 = __last2;
3884            value_type* __i2 = __j2;
3885            if (__comp(*__first1, *--__i2))
3886            {
3887                ::new(__j2) value_type(_VSTD::move(*__i2));
3888                __d.__incr((value_type*)0);
3889                for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
3890                    *__j2 = _VSTD::move(*__i2);
3891                *__j2 = _VSTD::move(*__first1);
3892            }
3893            else
3894            {
3895                ::new(__j2) value_type(_VSTD::move(*__first1));
3896                __d.__incr((value_type*)0);
3897            }
3898        }
3899        __h.release();
3900    }
3901}
3902
3903template <class _Compare, class _RandomAccessIterator>
3904void
3905__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3906{
3907    // _Compare is known to be a reference type
3908    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3909    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3910    const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
3911                                    is_trivially_copy_assignable<value_type>::value ? 30 : 6;
3912    while (true)
3913    {
3914    __restart:
3915        difference_type __len = __last - __first;
3916        switch (__len)
3917        {
3918        case 0:
3919        case 1:
3920            return;
3921        case 2:
3922            if (__comp(*--__last, *__first))
3923                swap(*__first, *__last);
3924            return;
3925        case 3:
3926            _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3927            return;
3928        case 4:
3929            _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3930            return;
3931        case 5:
3932            _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3933            return;
3934        }
3935        if (__len <= __limit)
3936        {
3937            _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
3938            return;
3939        }
3940        // __len > 5
3941        _RandomAccessIterator __m = __first;
3942        _RandomAccessIterator __lm1 = __last;
3943        --__lm1;
3944        unsigned __n_swaps;
3945        {
3946        difference_type __delta;
3947        if (__len >= 1000)
3948        {
3949            __delta = __len/2;
3950            __m += __delta;
3951            __delta /= 2;
3952            __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
3953        }
3954        else
3955        {
3956            __delta = __len/2;
3957            __m += __delta;
3958            __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
3959        }
3960        }
3961        // *__m is median
3962        // partition [__first, __m) < *__m and *__m <= [__m, __last)
3963        // (this inhibits tossing elements equivalent to __m around unnecessarily)
3964        _RandomAccessIterator __i = __first;
3965        _RandomAccessIterator __j = __lm1;
3966        // j points beyond range to be tested, *__m is known to be <= *__lm1
3967        // The search going up is known to be guarded but the search coming down isn't.
3968        // Prime the downward search with a guard.
3969        if (!__comp(*__i, *__m))  // if *__first == *__m
3970        {
3971            // *__first == *__m, *__first doesn't go in first part
3972            // manually guard downward moving __j against __i
3973            while (true)
3974            {
3975                if (__i == --__j)
3976                {
3977                    // *__first == *__m, *__m <= all other elements
3978                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
3979                    ++__i;  // __first + 1
3980                    __j = __last;
3981                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
3982                    {
3983                        while (true)
3984                        {
3985                            if (__i == __j)
3986                                return;  // [__first, __last) all equivalent elements
3987                            if (__comp(*__first, *__i))
3988                            {
3989                                swap(*__i, *__j);
3990                                ++__n_swaps;
3991                                ++__i;
3992                                break;
3993                            }
3994                            ++__i;
3995                        }
3996                    }
3997                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
3998                    if (__i == __j)
3999                        return;
4000                    while (true)
4001                    {
4002                        while (!__comp(*__first, *__i))
4003                            ++__i;
4004                        while (__comp(*__first, *--__j))
4005                            ;
4006                        if (__i >= __j)
4007                            break;
4008                        swap(*__i, *__j);
4009                        ++__n_swaps;
4010                        ++__i;
4011                    }
4012                    // [__first, __i) == *__first and *__first < [__i, __last)
4013                    // The first part is sorted, sort the secod part
4014                    // _VSTD::__sort<_Compare>(__i, __last, __comp);
4015                    __first = __i;
4016                    goto __restart;
4017                }
4018                if (__comp(*__j, *__m))
4019                {
4020                    swap(*__i, *__j);
4021                    ++__n_swaps;
4022                    break;  // found guard for downward moving __j, now use unguarded partition
4023                }
4024            }
4025        }
4026        // It is known that *__i < *__m
4027        ++__i;
4028        // j points beyond range to be tested, *__m is known to be <= *__lm1
4029        // if not yet partitioned...
4030        if (__i < __j)
4031        {
4032            // known that *(__i - 1) < *__m
4033            // known that __i <= __m
4034            while (true)
4035            {
4036                // __m still guards upward moving __i
4037                while (__comp(*__i, *__m))
4038                    ++__i;
4039                // It is now known that a guard exists for downward moving __j
4040                while (!__comp(*--__j, *__m))
4041                    ;
4042                if (__i > __j)
4043                    break;
4044                swap(*__i, *__j);
4045                ++__n_swaps;
4046                // It is known that __m != __j
4047                // If __m just moved, follow it
4048                if (__m == __i)
4049                    __m = __j;
4050                ++__i;
4051            }
4052        }
4053        // [__first, __i) < *__m and *__m <= [__i, __last)
4054        if (__i != __m && __comp(*__m, *__i))
4055        {
4056            swap(*__i, *__m);
4057            ++__n_swaps;
4058        }
4059        // [__first, __i) < *__i and *__i <= [__i+1, __last)
4060        // If we were given a perfect partition, see if insertion sort is quick...
4061        if (__n_swaps == 0)
4062        {
4063            bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
4064            if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
4065            {
4066                if (__fs)
4067                    return;
4068                __last = __i;
4069                continue;
4070            }
4071            else
4072            {
4073                if (__fs)
4074                {
4075                    __first = ++__i;
4076                    continue;
4077                }
4078            }
4079        }
4080        // sort smaller range with recursive call and larger with tail recursion elimination
4081        if (__i - __first < __last - __i)
4082        {
4083            _VSTD::__sort<_Compare>(__first, __i, __comp);
4084            // _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4085            __first = ++__i;
4086        }
4087        else
4088        {
4089            _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4090            // _VSTD::__sort<_Compare>(__first, __i, __comp);
4091            __last = __i;
4092        }
4093    }
4094}
4095
4096// This forwarder keeps the top call and the recursive calls using the same instantiation, forcing a reference _Compare
4097template <class _RandomAccessIterator, class _Compare>
4098inline _LIBCPP_INLINE_VISIBILITY
4099void
4100sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4101{
4102#ifdef _LIBCPP_DEBUG
4103    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4104    __debug_less<_Compare> __c(__comp);
4105    __sort<_Comp_ref>(__first, __last, __c);
4106#else  // _LIBCPP_DEBUG
4107    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4108    __sort<_Comp_ref>(__first, __last, __comp);
4109#endif  // _LIBCPP_DEBUG
4110}
4111
4112template <class _RandomAccessIterator>
4113inline _LIBCPP_INLINE_VISIBILITY
4114void
4115sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4116{
4117    _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4118}
4119
4120template <class _Tp>
4121inline _LIBCPP_INLINE_VISIBILITY
4122void
4123sort(_Tp** __first, _Tp** __last)
4124{
4125    _VSTD::sort((size_t*)__first, (size_t*)__last, __less<size_t>());
4126}
4127
4128template <class _Tp>
4129inline _LIBCPP_INLINE_VISIBILITY
4130void
4131sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last)
4132{
4133    _VSTD::sort(__first.base(), __last.base());
4134}
4135
4136template <class _Tp, class _Compare>
4137inline _LIBCPP_INLINE_VISIBILITY
4138void
4139sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last, _Compare __comp)
4140{
4141    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4142    _VSTD::sort<_Tp*, _Comp_ref>(__first.base(), __last.base(), __comp);
4143}
4144
4145_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
4146_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4147_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4148_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4149_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
4150_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4151_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
4152_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4153_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
4154_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4155_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4156_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>&))
4157_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
4158_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
4159_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4160
4161_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
4162_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4163_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4164_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4165_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
4166_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4167_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
4168_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4169_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
4170_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4171_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4172_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>&))
4173_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
4174_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
4175_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4176
4177_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>&))
4178
4179// lower_bound
4180
4181template <class _Compare, class _ForwardIterator, class _Tp>
4182_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4183__lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4184{
4185    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4186    difference_type __len = _VSTD::distance(__first, __last);
4187    while (__len != 0)
4188    {
4189        difference_type __l2 = __len / 2;
4190        _ForwardIterator __m = __first;
4191        _VSTD::advance(__m, __l2);
4192        if (__comp(*__m, __value_))
4193        {
4194            __first = ++__m;
4195            __len -= __l2 + 1;
4196        }
4197        else
4198            __len = __l2;
4199    }
4200    return __first;
4201}
4202
4203template <class _ForwardIterator, class _Tp, class _Compare>
4204inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4205_ForwardIterator
4206lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4207{
4208#ifdef _LIBCPP_DEBUG
4209    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4210    __debug_less<_Compare> __c(__comp);
4211    return __lower_bound<_Comp_ref>(__first, __last, __value_, __c);
4212#else  // _LIBCPP_DEBUG
4213    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4214    return __lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
4215#endif  // _LIBCPP_DEBUG
4216}
4217
4218template <class _ForwardIterator, class _Tp>
4219inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4220_ForwardIterator
4221lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4222{
4223    return _VSTD::lower_bound(__first, __last, __value_,
4224                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4225}
4226
4227// upper_bound
4228
4229template <class _Compare, class _ForwardIterator, class _Tp>
4230_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4231__upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4232{
4233    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4234    difference_type __len = _VSTD::distance(__first, __last);
4235    while (__len != 0)
4236    {
4237        difference_type __l2 = __len / 2;
4238        _ForwardIterator __m = __first;
4239        _VSTD::advance(__m, __l2);
4240        if (__comp(__value_, *__m))
4241            __len = __l2;
4242        else
4243        {
4244            __first = ++__m;
4245            __len -= __l2 + 1;
4246        }
4247    }
4248    return __first;
4249}
4250
4251template <class _ForwardIterator, class _Tp, class _Compare>
4252inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4253_ForwardIterator
4254upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4255{
4256#ifdef _LIBCPP_DEBUG
4257    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4258    __debug_less<_Compare> __c(__comp);
4259    return __upper_bound<_Comp_ref>(__first, __last, __value_, __c);
4260#else  // _LIBCPP_DEBUG
4261    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4262    return __upper_bound<_Comp_ref>(__first, __last, __value_, __comp);
4263#endif  // _LIBCPP_DEBUG
4264}
4265
4266template <class _ForwardIterator, class _Tp>
4267inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4268_ForwardIterator
4269upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4270{
4271    return _VSTD::upper_bound(__first, __last, __value_,
4272                             __less<_Tp, typename iterator_traits<_ForwardIterator>::value_type>());
4273}
4274
4275// equal_range
4276
4277template <class _Compare, class _ForwardIterator, class _Tp>
4278_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
4279__equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4280{
4281    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4282    difference_type __len = _VSTD::distance(__first, __last);
4283    while (__len != 0)
4284    {
4285        difference_type __l2 = __len / 2;
4286        _ForwardIterator __m = __first;
4287        _VSTD::advance(__m, __l2);
4288        if (__comp(*__m, __value_))
4289        {
4290            __first = ++__m;
4291            __len -= __l2 + 1;
4292        }
4293        else if (__comp(__value_, *__m))
4294        {
4295            __last = __m;
4296            __len = __l2;
4297        }
4298        else
4299        {
4300            _ForwardIterator __mp1 = __m;
4301            return pair<_ForwardIterator, _ForwardIterator>
4302                   (
4303                      __lower_bound<_Compare>(__first, __m, __value_, __comp),
4304                      __upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
4305                   );
4306        }
4307    }
4308    return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
4309}
4310
4311template <class _ForwardIterator, class _Tp, class _Compare>
4312inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4313pair<_ForwardIterator, _ForwardIterator>
4314equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4315{
4316#ifdef _LIBCPP_DEBUG
4317    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4318    __debug_less<_Compare> __c(__comp);
4319    return __equal_range<_Comp_ref>(__first, __last, __value_, __c);
4320#else  // _LIBCPP_DEBUG
4321    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4322    return __equal_range<_Comp_ref>(__first, __last, __value_, __comp);
4323#endif  // _LIBCPP_DEBUG
4324}
4325
4326template <class _ForwardIterator, class _Tp>
4327inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4328pair<_ForwardIterator, _ForwardIterator>
4329equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4330{
4331    return _VSTD::equal_range(__first, __last, __value_,
4332                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4333}
4334
4335// binary_search
4336
4337template <class _Compare, class _ForwardIterator, class _Tp>
4338inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4339bool
4340__binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4341{
4342    __first = __lower_bound<_Compare>(__first, __last, __value_, __comp);
4343    return __first != __last && !__comp(__value_, *__first);
4344}
4345
4346template <class _ForwardIterator, class _Tp, class _Compare>
4347inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4348bool
4349binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4350{
4351#ifdef _LIBCPP_DEBUG
4352    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4353    __debug_less<_Compare> __c(__comp);
4354    return __binary_search<_Comp_ref>(__first, __last, __value_, __c);
4355#else  // _LIBCPP_DEBUG
4356    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4357    return __binary_search<_Comp_ref>(__first, __last, __value_, __comp);
4358#endif  // _LIBCPP_DEBUG
4359}
4360
4361template <class _ForwardIterator, class _Tp>
4362inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4363bool
4364binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4365{
4366    return _VSTD::binary_search(__first, __last, __value_,
4367                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4368}
4369
4370// merge
4371
4372template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4373_OutputIterator
4374__merge(_InputIterator1 __first1, _InputIterator1 __last1,
4375        _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4376{
4377    for (; __first1 != __last1; ++__result)
4378    {
4379        if (__first2 == __last2)
4380            return _VSTD::copy(__first1, __last1, __result);
4381        if (__comp(*__first2, *__first1))
4382        {
4383            *__result = *__first2;
4384            ++__first2;
4385        }
4386        else
4387        {
4388            *__result = *__first1;
4389            ++__first1;
4390        }
4391    }
4392    return _VSTD::copy(__first2, __last2, __result);
4393}
4394
4395template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
4396inline _LIBCPP_INLINE_VISIBILITY
4397_OutputIterator
4398merge(_InputIterator1 __first1, _InputIterator1 __last1,
4399      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4400{
4401#ifdef _LIBCPP_DEBUG
4402    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4403    __debug_less<_Compare> __c(__comp);
4404    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __c);
4405#else  // _LIBCPP_DEBUG
4406    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4407    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
4408#endif  // _LIBCPP_DEBUG
4409}
4410
4411template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
4412inline _LIBCPP_INLINE_VISIBILITY
4413_OutputIterator
4414merge(_InputIterator1 __first1, _InputIterator1 __last1,
4415      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
4416{
4417    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
4418    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
4419    return merge(__first1, __last1, __first2, __last2, __result, __less<__v1, __v2>());
4420}
4421
4422// inplace_merge
4423
4424template <class _Compare, class _InputIterator1, class _InputIterator2,
4425          class _OutputIterator>
4426void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
4427                          _InputIterator2 __first2, _InputIterator2 __last2,
4428                          _OutputIterator __result, _Compare __comp)
4429{
4430    for (; __first1 != __last1; ++__result)
4431    {
4432        if (__first2 == __last2)
4433        {
4434            _VSTD::move(__first1, __last1, __result);
4435            return;
4436        }
4437
4438        if (__comp(*__first2, *__first1))
4439        {
4440            *__result = _VSTD::move(*__first2);
4441            ++__first2;
4442        }
4443        else
4444        {
4445            *__result = _VSTD::move(*__first1);
4446            ++__first1;
4447        }
4448    }
4449    // __first2 through __last2 are already in the right spot.
4450}
4451
4452template <class _Compare, class _BidirectionalIterator>
4453void
4454__buffered_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)
4458{
4459    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4460    __destruct_n __d(0);
4461    unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4462    if (__len1 <= __len2)
4463    {
4464        value_type* __p = __buff;
4465        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4466            ::new(__p) value_type(_VSTD::move(*__i));
4467        __half_inplace_merge(__buff, __p, __middle, __last, __first, __comp);
4468    }
4469    else
4470    {
4471        value_type* __p = __buff;
4472        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4473            ::new(__p) value_type(_VSTD::move(*__i));
4474        typedef reverse_iterator<_BidirectionalIterator> _RBi;
4475        typedef reverse_iterator<value_type*> _Rv;
4476        __half_inplace_merge(_Rv(__p), _Rv(__buff),
4477                             _RBi(__middle), _RBi(__first),
4478                             _RBi(__last), __invert<_Compare>(__comp));
4479    }
4480}
4481
4482template <class _Compare, class _BidirectionalIterator>
4483void
4484__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4485                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
4486                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
4487                typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
4488{
4489    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4490    while (true)
4491    {
4492        // if __middle == __last, we're done
4493        if (__len2 == 0)
4494            return;
4495        if (__len1 <= __buff_size || __len2 <= __buff_size)
4496            return __buffered_inplace_merge<_Compare>
4497                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
4498        // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
4499        for (; true; ++__first, (void) --__len1)
4500        {
4501            if (__len1 == 0)
4502                return;
4503            if (__comp(*__middle, *__first))
4504                break;
4505        }
4506        // __first < __middle < __last
4507        // *__first > *__middle
4508        // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
4509        //     all elements in:
4510        //         [__first, __m1)  <= [__middle, __m2)
4511        //         [__middle, __m2) <  [__m1, __middle)
4512        //         [__m1, __middle) <= [__m2, __last)
4513        //     and __m1 or __m2 is in the middle of its range
4514        _BidirectionalIterator __m1;  // "median" of [__first, __middle)
4515        _BidirectionalIterator __m2;  // "median" of [__middle, __last)
4516        difference_type __len11;      // distance(__first, __m1)
4517        difference_type __len21;      // distance(__middle, __m2)
4518        // binary search smaller range
4519        if (__len1 < __len2)
4520        {   // __len >= 1, __len2 >= 2
4521            __len21 = __len2 / 2;
4522            __m2 = __middle;
4523            _VSTD::advance(__m2, __len21);
4524            __m1 = __upper_bound<_Compare>(__first, __middle, *__m2, __comp);
4525            __len11 = _VSTD::distance(__first, __m1);
4526        }
4527        else
4528        {
4529            if (__len1 == 1)
4530            {   // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
4531                // It is known *__first > *__middle
4532                swap(*__first, *__middle);
4533                return;
4534            }
4535            // __len1 >= 2, __len2 >= 1
4536            __len11 = __len1 / 2;
4537            __m1 = __first;
4538            _VSTD::advance(__m1, __len11);
4539            __m2 = __lower_bound<_Compare>(__middle, __last, *__m1, __comp);
4540            __len21 = _VSTD::distance(__middle, __m2);
4541        }
4542        difference_type __len12 = __len1 - __len11;  // distance(__m1, __middle)
4543        difference_type __len22 = __len2 - __len21;  // distance(__m2, __last)
4544        // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
4545        // swap middle two partitions
4546        __middle = _VSTD::rotate(__m1, __middle, __m2);
4547        // __len12 and __len21 now have swapped meanings
4548        // merge smaller range with recurisve call and larger with tail recursion elimination
4549        if (__len11 + __len21 < __len12 + __len22)
4550        {
4551            __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4552//          __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4553            __first = __middle;
4554            __middle = __m2;
4555            __len1 = __len12;
4556            __len2 = __len22;
4557        }
4558        else
4559        {
4560            __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4561//          __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4562            __last = __middle;
4563            __middle = __m1;
4564            __len1 = __len11;
4565            __len2 = __len21;
4566        }
4567    }
4568}
4569
4570template <class _BidirectionalIterator, class _Compare>
4571inline _LIBCPP_INLINE_VISIBILITY
4572void
4573inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4574              _Compare __comp)
4575{
4576    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4577    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4578    difference_type __len1 = _VSTD::distance(__first, __middle);
4579    difference_type __len2 = _VSTD::distance(__middle, __last);
4580    difference_type __buf_size = _VSTD::min(__len1, __len2);
4581    pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
4582    unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
4583
4584#ifdef _LIBCPP_DEBUG
4585    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4586    __debug_less<_Compare> __c(__comp);
4587    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __c, __len1, __len2,
4588                                            __buf.first, __buf.second);
4589#else  // _LIBCPP_DEBUG
4590    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4591    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
4592                                            __buf.first, __buf.second);
4593#endif  // _LIBCPP_DEBUG
4594}
4595
4596template <class _BidirectionalIterator>
4597inline _LIBCPP_INLINE_VISIBILITY
4598void
4599inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
4600{
4601    _VSTD::inplace_merge(__first, __middle, __last,
4602                        __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
4603}
4604
4605// stable_sort
4606
4607template <class _Compare, class _InputIterator1, class _InputIterator2>
4608void
4609__merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
4610        _InputIterator2 __first2, _InputIterator2 __last2,
4611        typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
4612{
4613    typedef typename iterator_traits<_InputIterator1>::value_type value_type;
4614    __destruct_n __d(0);
4615    unique_ptr<value_type, __destruct_n&> __h(__result, __d);
4616    for (; true; ++__result)
4617    {
4618        if (__first1 == __last1)
4619        {
4620            for (; __first2 != __last2; ++__first2, ++__result, __d.__incr((value_type*)0))
4621                ::new (__result) value_type(_VSTD::move(*__first2));
4622            __h.release();
4623            return;
4624        }
4625        if (__first2 == __last2)
4626        {
4627            for (; __first1 != __last1; ++__first1, ++__result, __d.__incr((value_type*)0))
4628                ::new (__result) value_type(_VSTD::move(*__first1));
4629            __h.release();
4630            return;
4631        }
4632        if (__comp(*__first2, *__first1))
4633        {
4634            ::new (__result) value_type(_VSTD::move(*__first2));
4635            __d.__incr((value_type*)0);
4636            ++__first2;
4637        }
4638        else
4639        {
4640            ::new (__result) value_type(_VSTD::move(*__first1));
4641            __d.__incr((value_type*)0);
4642            ++__first1;
4643        }
4644    }
4645}
4646
4647template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4648void
4649__merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
4650        _InputIterator2 __first2, _InputIterator2 __last2,
4651        _OutputIterator __result, _Compare __comp)
4652{
4653    for (; __first1 != __last1; ++__result)
4654    {
4655        if (__first2 == __last2)
4656        {
4657            for (; __first1 != __last1; ++__first1, ++__result)
4658                *__result = _VSTD::move(*__first1);
4659            return;
4660        }
4661        if (__comp(*__first2, *__first1))
4662        {
4663            *__result = _VSTD::move(*__first2);
4664            ++__first2;
4665        }
4666        else
4667        {
4668            *__result = _VSTD::move(*__first1);
4669            ++__first1;
4670        }
4671    }
4672    for (; __first2 != __last2; ++__first2, ++__result)
4673        *__result = _VSTD::move(*__first2);
4674}
4675
4676template <class _Compare, class _RandomAccessIterator>
4677void
4678__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4679              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4680              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
4681
4682template <class _Compare, class _RandomAccessIterator>
4683void
4684__stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
4685                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4686                   typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
4687{
4688    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4689    switch (__len)
4690    {
4691    case 0:
4692        return;
4693    case 1:
4694        ::new(__first2) value_type(_VSTD::move(*__first1));
4695        return;
4696    case 2:
4697       __destruct_n __d(0);
4698        unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
4699         if (__comp(*--__last1, *__first1))
4700        {
4701            ::new(__first2) value_type(_VSTD::move(*__last1));
4702            __d.__incr((value_type*)0);
4703            ++__first2;
4704            ::new(__first2) value_type(_VSTD::move(*__first1));
4705        }
4706        else
4707        {
4708            ::new(__first2) value_type(_VSTD::move(*__first1));
4709            __d.__incr((value_type*)0);
4710            ++__first2;
4711            ::new(__first2) value_type(_VSTD::move(*__last1));
4712        }
4713        __h2.release();
4714        return;
4715    }
4716    if (__len <= 8)
4717    {
4718        __insertion_sort_move<_Compare>(__first1, __last1, __first2, __comp);
4719        return;
4720    }
4721    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4722    _RandomAccessIterator __m = __first1 + __l2;
4723    __stable_sort<_Compare>(__first1, __m, __comp, __l2, __first2, __l2);
4724    __stable_sort<_Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
4725    __merge_move_construct<_Compare>(__first1, __m, __m, __last1, __first2, __comp);
4726}
4727
4728template <class _Tp>
4729struct __stable_sort_switch
4730{
4731    static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
4732};
4733
4734template <class _Compare, class _RandomAccessIterator>
4735void
4736__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4737              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4738              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
4739{
4740    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4741    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4742    switch (__len)
4743    {
4744    case 0:
4745    case 1:
4746        return;
4747    case 2:
4748        if (__comp(*--__last, *__first))
4749            swap(*__first, *__last);
4750        return;
4751    }
4752    if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4753    {
4754        __insertion_sort<_Compare>(__first, __last, __comp);
4755        return;
4756    }
4757    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4758    _RandomAccessIterator __m = __first + __l2;
4759    if (__len <= __buff_size)
4760    {
4761        __destruct_n __d(0);
4762        unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4763        __stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
4764        __d.__set(__l2, (value_type*)0);
4765        __stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
4766        __d.__set(__len, (value_type*)0);
4767        __merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
4768//         __merge<_Compare>(move_iterator<value_type*>(__buff),
4769//                           move_iterator<value_type*>(__buff + __l2),
4770//                           move_iterator<_RandomAccessIterator>(__buff + __l2),
4771//                           move_iterator<_RandomAccessIterator>(__buff + __len),
4772//                           __first, __comp);
4773        return;
4774    }
4775    __stable_sort<_Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
4776    __stable_sort<_Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
4777    __inplace_merge<_Compare>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
4778}
4779
4780template <class _RandomAccessIterator, class _Compare>
4781inline _LIBCPP_INLINE_VISIBILITY
4782void
4783stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4784{
4785    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4786    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4787    difference_type __len = __last - __first;
4788    pair<value_type*, ptrdiff_t> __buf(0, 0);
4789    unique_ptr<value_type, __return_temporary_buffer> __h;
4790    if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4791    {
4792        __buf = _VSTD::get_temporary_buffer<value_type>(__len);
4793        __h.reset(__buf.first);
4794    }
4795#ifdef _LIBCPP_DEBUG
4796    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4797    __debug_less<_Compare> __c(__comp);
4798    __stable_sort<_Comp_ref>(__first, __last, __c, __len, __buf.first, __buf.second);
4799#else  // _LIBCPP_DEBUG
4800    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4801    __stable_sort<_Comp_ref>(__first, __last, __comp, __len, __buf.first, __buf.second);
4802#endif  // _LIBCPP_DEBUG
4803}
4804
4805template <class _RandomAccessIterator>
4806inline _LIBCPP_INLINE_VISIBILITY
4807void
4808stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4809{
4810    _VSTD::stable_sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4811}
4812
4813// is_heap_until
4814
4815template <class _RandomAccessIterator, class _Compare>
4816_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
4817is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4818{
4819    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4820    difference_type __len = __last - __first;
4821    difference_type __p = 0;
4822    difference_type __c = 1;
4823    _RandomAccessIterator __pp = __first;
4824    while (__c < __len)
4825    {
4826        _RandomAccessIterator __cp = __first + __c;
4827        if (__comp(*__pp, *__cp))
4828            return __cp;
4829        ++__c;
4830        ++__cp;
4831        if (__c == __len)
4832            return __last;
4833        if (__comp(*__pp, *__cp))
4834            return __cp;
4835        ++__p;
4836        ++__pp;
4837        __c = 2 * __p + 1;
4838    }
4839    return __last;
4840}
4841
4842template<class _RandomAccessIterator>
4843inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4844_RandomAccessIterator
4845is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
4846{
4847    return _VSTD::is_heap_until(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4848}
4849
4850// is_heap
4851
4852template <class _RandomAccessIterator, class _Compare>
4853inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4854bool
4855is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4856{
4857    return _VSTD::is_heap_until(__first, __last, __comp) == __last;
4858}
4859
4860template<class _RandomAccessIterator>
4861inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4862bool
4863is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4864{
4865    return _VSTD::is_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4866}
4867
4868// push_heap
4869
4870template <class _Compare, class _RandomAccessIterator>
4871void
4872__sift_up(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4873          typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4874{
4875    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4876    if (__len > 1)
4877    {
4878        __len = (__len - 2) / 2;
4879        _RandomAccessIterator __ptr = __first + __len;
4880        if (__comp(*__ptr, *--__last))
4881        {
4882            value_type __t(_VSTD::move(*__last));
4883            do
4884            {
4885                *__last = _VSTD::move(*__ptr);
4886                __last = __ptr;
4887                if (__len == 0)
4888                    break;
4889                __len = (__len - 1) / 2;
4890                __ptr = __first + __len;
4891            } while (__comp(*__ptr, __t));
4892            *__last = _VSTD::move(__t);
4893        }
4894    }
4895}
4896
4897template <class _RandomAccessIterator, class _Compare>
4898inline _LIBCPP_INLINE_VISIBILITY
4899void
4900push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4901{
4902#ifdef _LIBCPP_DEBUG
4903    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4904    __debug_less<_Compare> __c(__comp);
4905    __sift_up<_Comp_ref>(__first, __last, __c, __last - __first);
4906#else  // _LIBCPP_DEBUG
4907    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4908    __sift_up<_Comp_ref>(__first, __last, __comp, __last - __first);
4909#endif  // _LIBCPP_DEBUG
4910}
4911
4912template <class _RandomAccessIterator>
4913inline _LIBCPP_INLINE_VISIBILITY
4914void
4915push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4916{
4917    _VSTD::push_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4918}
4919
4920// pop_heap
4921
4922template <class _Compare, class _RandomAccessIterator>
4923void
4924__sift_down(_RandomAccessIterator __first, _RandomAccessIterator /*__last*/,
4925            _Compare __comp,
4926            typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4927            _RandomAccessIterator __start)
4928{
4929    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4930    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4931    // left-child of __start is at 2 * __start + 1
4932    // right-child of __start is at 2 * __start + 2
4933    difference_type __child = __start - __first;
4934
4935    if (__len < 2 || (__len - 2) / 2 < __child)
4936        return;
4937
4938    __child = 2 * __child + 1;
4939    _RandomAccessIterator __child_i = __first + __child;
4940
4941    if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4942        // right-child exists and is greater than left-child
4943        ++__child_i;
4944        ++__child;
4945    }
4946
4947    // check if we are in heap-order
4948    if (__comp(*__child_i, *__start))
4949        // we are, __start is larger than it's largest child
4950        return;
4951
4952    value_type __top(_VSTD::move(*__start));
4953    do
4954    {
4955        // we are not in heap-order, swap the parent with it's largest child
4956        *__start = _VSTD::move(*__child_i);
4957        __start = __child_i;
4958
4959        if ((__len - 2) / 2 < __child)
4960            break;
4961
4962        // recompute the child based off of the updated parent
4963        __child = 2 * __child + 1;
4964        __child_i = __first + __child;
4965
4966        if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4967            // right-child exists and is greater than left-child
4968            ++__child_i;
4969            ++__child;
4970        }
4971
4972        // check if we are in heap-order
4973    } while (!__comp(*__child_i, __top));
4974    *__start = _VSTD::move(__top);
4975}
4976
4977template <class _Compare, class _RandomAccessIterator>
4978inline _LIBCPP_INLINE_VISIBILITY
4979void
4980__pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4981           typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4982{
4983    if (__len > 1)
4984    {
4985        swap(*__first, *--__last);
4986        __sift_down<_Compare>(__first, __last, __comp, __len - 1, __first);
4987    }
4988}
4989
4990template <class _RandomAccessIterator, class _Compare>
4991inline _LIBCPP_INLINE_VISIBILITY
4992void
4993pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4994{
4995#ifdef _LIBCPP_DEBUG
4996    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
4997    __debug_less<_Compare> __c(__comp);
4998    __pop_heap<_Comp_ref>(__first, __last, __c, __last - __first);
4999#else  // _LIBCPP_DEBUG
5000    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5001    __pop_heap<_Comp_ref>(__first, __last, __comp, __last - __first);
5002#endif  // _LIBCPP_DEBUG
5003}
5004
5005template <class _RandomAccessIterator>
5006inline _LIBCPP_INLINE_VISIBILITY
5007void
5008pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
5009{
5010    _VSTD::pop_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5011}
5012
5013// make_heap
5014
5015template <class _Compare, class _RandomAccessIterator>
5016void
5017__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5018{
5019    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5020    difference_type __n = __last - __first;
5021    if (__n > 1)
5022    {
5023        // start from the first parent, there is no need to consider children
5024        for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start)
5025        {
5026            __sift_down<_Compare>(__first, __last, __comp, __n, __first + __start);
5027        }
5028    }
5029}
5030
5031template <class _RandomAccessIterator, class _Compare>
5032inline _LIBCPP_INLINE_VISIBILITY
5033void
5034make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5035{
5036#ifdef _LIBCPP_DEBUG
5037    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5038    __debug_less<_Compare> __c(__comp);
5039    __make_heap<_Comp_ref>(__first, __last, __c);
5040#else  // _LIBCPP_DEBUG
5041    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5042    __make_heap<_Comp_ref>(__first, __last, __comp);
5043#endif  // _LIBCPP_DEBUG
5044}
5045
5046template <class _RandomAccessIterator>
5047inline _LIBCPP_INLINE_VISIBILITY
5048void
5049make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
5050{
5051    _VSTD::make_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5052}
5053
5054// sort_heap
5055
5056template <class _Compare, class _RandomAccessIterator>
5057void
5058__sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5059{
5060    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5061    for (difference_type __n = __last - __first; __n > 1; --__last, --__n)
5062        __pop_heap<_Compare>(__first, __last, __comp, __n);
5063}
5064
5065template <class _RandomAccessIterator, class _Compare>
5066inline _LIBCPP_INLINE_VISIBILITY
5067void
5068sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5069{
5070#ifdef _LIBCPP_DEBUG
5071    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5072    __debug_less<_Compare> __c(__comp);
5073    __sort_heap<_Comp_ref>(__first, __last, __c);
5074#else  // _LIBCPP_DEBUG
5075    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5076    __sort_heap<_Comp_ref>(__first, __last, __comp);
5077#endif  // _LIBCPP_DEBUG
5078}
5079
5080template <class _RandomAccessIterator>
5081inline _LIBCPP_INLINE_VISIBILITY
5082void
5083sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
5084{
5085    _VSTD::sort_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5086}
5087
5088// partial_sort
5089
5090template <class _Compare, class _RandomAccessIterator>
5091void
5092__partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5093             _Compare __comp)
5094{
5095    __make_heap<_Compare>(__first, __middle, __comp);
5096    typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
5097    for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
5098    {
5099        if (__comp(*__i, *__first))
5100        {
5101            swap(*__i, *__first);
5102            __sift_down<_Compare>(__first, __middle, __comp, __len, __first);
5103        }
5104    }
5105    __sort_heap<_Compare>(__first, __middle, __comp);
5106}
5107
5108template <class _RandomAccessIterator, class _Compare>
5109inline _LIBCPP_INLINE_VISIBILITY
5110void
5111partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5112             _Compare __comp)
5113{
5114#ifdef _LIBCPP_DEBUG
5115    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5116    __debug_less<_Compare> __c(__comp);
5117    __partial_sort<_Comp_ref>(__first, __middle, __last, __c);
5118#else  // _LIBCPP_DEBUG
5119    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5120    __partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
5121#endif  // _LIBCPP_DEBUG
5122}
5123
5124template <class _RandomAccessIterator>
5125inline _LIBCPP_INLINE_VISIBILITY
5126void
5127partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
5128{
5129    _VSTD::partial_sort(__first, __middle, __last,
5130                       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5131}
5132
5133// partial_sort_copy
5134
5135template <class _Compare, class _InputIterator, class _RandomAccessIterator>
5136_RandomAccessIterator
5137__partial_sort_copy(_InputIterator __first, _InputIterator __last,
5138                    _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5139{
5140    _RandomAccessIterator __r = __result_first;
5141    if (__r != __result_last)
5142    {
5143        for (; __first != __last && __r != __result_last; (void) ++__first, ++__r)
5144            *__r = *__first;
5145        __make_heap<_Compare>(__result_first, __r, __comp);
5146        typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
5147        for (; __first != __last; ++__first)
5148            if (__comp(*__first, *__result_first))
5149            {
5150                *__result_first = *__first;
5151                __sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
5152            }
5153        __sort_heap<_Compare>(__result_first, __r, __comp);
5154    }
5155    return __r;
5156}
5157
5158template <class _InputIterator, class _RandomAccessIterator, class _Compare>
5159inline _LIBCPP_INLINE_VISIBILITY
5160_RandomAccessIterator
5161partial_sort_copy(_InputIterator __first, _InputIterator __last,
5162                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5163{
5164#ifdef _LIBCPP_DEBUG
5165    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5166    __debug_less<_Compare> __c(__comp);
5167    return __partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __c);
5168#else  // _LIBCPP_DEBUG
5169    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5170    return __partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
5171#endif  // _LIBCPP_DEBUG
5172}
5173
5174template <class _InputIterator, class _RandomAccessIterator>
5175inline _LIBCPP_INLINE_VISIBILITY
5176_RandomAccessIterator
5177partial_sort_copy(_InputIterator __first, _InputIterator __last,
5178                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
5179{
5180    return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
5181                                   __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5182}
5183
5184// nth_element
5185
5186template <class _Compare, class _RandomAccessIterator>
5187void
5188__nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5189{
5190    // _Compare is known to be a reference type
5191    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5192    const difference_type __limit = 7;
5193    while (true)
5194    {
5195    __restart:
5196        if (__nth == __last)
5197            return;
5198        difference_type __len = __last - __first;
5199        switch (__len)
5200        {
5201        case 0:
5202        case 1:
5203            return;
5204        case 2:
5205            if (__comp(*--__last, *__first))
5206                swap(*__first, *__last);
5207            return;
5208        case 3:
5209            {
5210            _RandomAccessIterator __m = __first;
5211            _VSTD::__sort3<_Compare>(__first, ++__m, --__last, __comp);
5212            return;
5213            }
5214        }
5215        if (__len <= __limit)
5216        {
5217            __selection_sort<_Compare>(__first, __last, __comp);
5218            return;
5219        }
5220        // __len > __limit >= 3
5221        _RandomAccessIterator __m = __first + __len/2;
5222        _RandomAccessIterator __lm1 = __last;
5223        unsigned __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, --__lm1, __comp);
5224        // *__m is median
5225        // partition [__first, __m) < *__m and *__m <= [__m, __last)
5226        // (this inhibits tossing elements equivalent to __m around unnecessarily)
5227        _RandomAccessIterator __i = __first;
5228        _RandomAccessIterator __j = __lm1;
5229        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5230        // The search going up is known to be guarded but the search coming down isn't.
5231        // Prime the downward search with a guard.
5232        if (!__comp(*__i, *__m))  // if *__first == *__m
5233        {
5234            // *__first == *__m, *__first doesn't go in first part
5235            // manually guard downward moving __j against __i
5236            while (true)
5237            {
5238                if (__i == --__j)
5239                {
5240                    // *__first == *__m, *__m <= all other elements
5241                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
5242                    ++__i;  // __first + 1
5243                    __j = __last;
5244                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
5245                    {
5246                        while (true)
5247                        {
5248                            if (__i == __j)
5249                                return;  // [__first, __last) all equivalent elements
5250                            if (__comp(*__first, *__i))
5251                            {
5252                                swap(*__i, *__j);
5253                                ++__n_swaps;
5254                                ++__i;
5255                                break;
5256                            }
5257                            ++__i;
5258                        }
5259                    }
5260                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
5261                    if (__i == __j)
5262                        return;
5263                    while (true)
5264                    {
5265                        while (!__comp(*__first, *__i))
5266                            ++__i;
5267                        while (__comp(*__first, *--__j))
5268                            ;
5269                        if (__i >= __j)
5270                            break;
5271                        swap(*__i, *__j);
5272                        ++__n_swaps;
5273                        ++__i;
5274                    }
5275                    // [__first, __i) == *__first and *__first < [__i, __last)
5276                    // The first part is sorted,
5277                    if (__nth < __i)
5278                        return;
5279                    // __nth_element the secod part
5280                    // __nth_element<_Compare>(__i, __nth, __last, __comp);
5281                    __first = __i;
5282                    goto __restart;
5283                }
5284                if (__comp(*__j, *__m))
5285                {
5286                    swap(*__i, *__j);
5287                    ++__n_swaps;
5288                    break;  // found guard for downward moving __j, now use unguarded partition
5289                }
5290            }
5291        }
5292        ++__i;
5293        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5294        // if not yet partitioned...
5295        if (__i < __j)
5296        {
5297            // known that *(__i - 1) < *__m
5298            while (true)
5299            {
5300                // __m still guards upward moving __i
5301                while (__comp(*__i, *__m))
5302                    ++__i;
5303                // It is now known that a guard exists for downward moving __j
5304                while (!__comp(*--__j, *__m))
5305                    ;
5306                if (__i >= __j)
5307                    break;
5308                swap(*__i, *__j);
5309                ++__n_swaps;
5310                // It is known that __m != __j
5311                // If __m just moved, follow it
5312                if (__m == __i)
5313                    __m = __j;
5314                ++__i;
5315            }
5316        }
5317        // [__first, __i) < *__m and *__m <= [__i, __last)
5318        if (__i != __m && __comp(*__m, *__i))
5319        {
5320            swap(*__i, *__m);
5321            ++__n_swaps;
5322        }
5323        // [__first, __i) < *__i and *__i <= [__i+1, __last)
5324        if (__nth == __i)
5325            return;
5326        if (__n_swaps == 0)
5327        {
5328            // We were given a perfectly partitioned sequence.  Coincidence?
5329            if (__nth < __i)
5330            {
5331                // Check for [__first, __i) already sorted
5332                __j = __m = __first;
5333                while (++__j != __i)
5334                {
5335                    if (__comp(*__j, *__m))
5336                        // not yet sorted, so sort
5337                        goto not_sorted;
5338                    __m = __j;
5339                }
5340                // [__first, __i) sorted
5341                return;
5342            }
5343            else
5344            {
5345                // Check for [__i, __last) already sorted
5346                __j = __m = __i;
5347                while (++__j != __last)
5348                {
5349                    if (__comp(*__j, *__m))
5350                        // not yet sorted, so sort
5351                        goto not_sorted;
5352                    __m = __j;
5353                }
5354                // [__i, __last) sorted
5355                return;
5356            }
5357        }
5358not_sorted:
5359        // __nth_element on range containing __nth
5360        if (__nth < __i)
5361        {
5362            // __nth_element<_Compare>(__first, __nth, __i, __comp);
5363            __last = __i;
5364        }
5365        else
5366        {
5367            // __nth_element<_Compare>(__i+1, __nth, __last, __comp);
5368            __first = ++__i;
5369        }
5370    }
5371}
5372
5373template <class _RandomAccessIterator, class _Compare>
5374inline _LIBCPP_INLINE_VISIBILITY
5375void
5376nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5377{
5378#ifdef _LIBCPP_DEBUG
5379    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5380    __debug_less<_Compare> __c(__comp);
5381    __nth_element<_Comp_ref>(__first, __nth, __last, __c);
5382#else  // _LIBCPP_DEBUG
5383    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5384    __nth_element<_Comp_ref>(__first, __nth, __last, __comp);
5385#endif  // _LIBCPP_DEBUG
5386}
5387
5388template <class _RandomAccessIterator>
5389inline _LIBCPP_INLINE_VISIBILITY
5390void
5391nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
5392{
5393    _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5394}
5395
5396// includes
5397
5398template <class _Compare, class _InputIterator1, class _InputIterator2>
5399bool
5400__includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5401           _Compare __comp)
5402{
5403    for (; __first2 != __last2; ++__first1)
5404    {
5405        if (__first1 == __last1 || __comp(*__first2, *__first1))
5406            return false;
5407        if (!__comp(*__first1, *__first2))
5408            ++__first2;
5409    }
5410    return true;
5411}
5412
5413template <class _InputIterator1, class _InputIterator2, class _Compare>
5414inline _LIBCPP_INLINE_VISIBILITY
5415bool
5416includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5417         _Compare __comp)
5418{
5419#ifdef _LIBCPP_DEBUG
5420    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5421    __debug_less<_Compare> __c(__comp);
5422    return __includes<_Comp_ref>(__first1, __last1, __first2, __last2, __c);
5423#else  // _LIBCPP_DEBUG
5424    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5425    return __includes<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5426#endif  // _LIBCPP_DEBUG
5427}
5428
5429template <class _InputIterator1, class _InputIterator2>
5430inline _LIBCPP_INLINE_VISIBILITY
5431bool
5432includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
5433{
5434    return _VSTD::includes(__first1, __last1, __first2, __last2,
5435                          __less<typename iterator_traits<_InputIterator1>::value_type,
5436                                 typename iterator_traits<_InputIterator2>::value_type>());
5437}
5438
5439// set_union
5440
5441template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5442_OutputIterator
5443__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5444            _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5445{
5446    for (; __first1 != __last1; ++__result)
5447    {
5448        if (__first2 == __last2)
5449            return _VSTD::copy(__first1, __last1, __result);
5450        if (__comp(*__first2, *__first1))
5451        {
5452            *__result = *__first2;
5453            ++__first2;
5454        }
5455        else
5456        {
5457            if (!__comp(*__first1, *__first2))
5458                ++__first2;
5459            *__result = *__first1;
5460            ++__first1;
5461        }
5462    }
5463    return _VSTD::copy(__first2, __last2, __result);
5464}
5465
5466template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5467inline _LIBCPP_INLINE_VISIBILITY
5468_OutputIterator
5469set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5470          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5471{
5472#ifdef _LIBCPP_DEBUG
5473    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5474    __debug_less<_Compare> __c(__comp);
5475    return __set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __c);
5476#else  // _LIBCPP_DEBUG
5477    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5478    return __set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5479#endif  // _LIBCPP_DEBUG
5480}
5481
5482template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5483inline _LIBCPP_INLINE_VISIBILITY
5484_OutputIterator
5485set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5486          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5487{
5488    return _VSTD::set_union(__first1, __last1, __first2, __last2, __result,
5489                          __less<typename iterator_traits<_InputIterator1>::value_type,
5490                                 typename iterator_traits<_InputIterator2>::value_type>());
5491}
5492
5493// set_intersection
5494
5495template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5496_OutputIterator
5497__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5498                   _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5499{
5500    while (__first1 != __last1 && __first2 != __last2)
5501    {
5502        if (__comp(*__first1, *__first2))
5503            ++__first1;
5504        else
5505        {
5506            if (!__comp(*__first2, *__first1))
5507            {
5508                *__result = *__first1;
5509                ++__result;
5510                ++__first1;
5511            }
5512            ++__first2;
5513        }
5514    }
5515    return __result;
5516}
5517
5518template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5519inline _LIBCPP_INLINE_VISIBILITY
5520_OutputIterator
5521set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5522                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5523{
5524#ifdef _LIBCPP_DEBUG
5525    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5526    __debug_less<_Compare> __c(__comp);
5527    return __set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __c);
5528#else  // _LIBCPP_DEBUG
5529    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5530    return __set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5531#endif  // _LIBCPP_DEBUG
5532}
5533
5534template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5535inline _LIBCPP_INLINE_VISIBILITY
5536_OutputIterator
5537set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5538                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5539{
5540    return _VSTD::set_intersection(__first1, __last1, __first2, __last2, __result,
5541                                  __less<typename iterator_traits<_InputIterator1>::value_type,
5542                                         typename iterator_traits<_InputIterator2>::value_type>());
5543}
5544
5545// set_difference
5546
5547template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5548_OutputIterator
5549__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5550                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5551{
5552    while (__first1 != __last1)
5553    {
5554        if (__first2 == __last2)
5555            return _VSTD::copy(__first1, __last1, __result);
5556        if (__comp(*__first1, *__first2))
5557        {
5558            *__result = *__first1;
5559            ++__result;
5560            ++__first1;
5561        }
5562        else
5563        {
5564            if (!__comp(*__first2, *__first1))
5565                ++__first1;
5566            ++__first2;
5567        }
5568    }
5569    return __result;
5570}
5571
5572template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5573inline _LIBCPP_INLINE_VISIBILITY
5574_OutputIterator
5575set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5576               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5577{
5578#ifdef _LIBCPP_DEBUG
5579    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5580    __debug_less<_Compare> __c(__comp);
5581    return __set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __c);
5582#else  // _LIBCPP_DEBUG
5583    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5584    return __set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5585#endif  // _LIBCPP_DEBUG
5586}
5587
5588template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5589inline _LIBCPP_INLINE_VISIBILITY
5590_OutputIterator
5591set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5592               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5593{
5594    return _VSTD::set_difference(__first1, __last1, __first2, __last2, __result,
5595                                __less<typename iterator_traits<_InputIterator1>::value_type,
5596                                       typename iterator_traits<_InputIterator2>::value_type>());
5597}
5598
5599// set_symmetric_difference
5600
5601template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5602_OutputIterator
5603__set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5604                           _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5605{
5606    while (__first1 != __last1)
5607    {
5608        if (__first2 == __last2)
5609            return _VSTD::copy(__first1, __last1, __result);
5610        if (__comp(*__first1, *__first2))
5611        {
5612            *__result = *__first1;
5613            ++__result;
5614            ++__first1;
5615        }
5616        else
5617        {
5618            if (__comp(*__first2, *__first1))
5619            {
5620                *__result = *__first2;
5621                ++__result;
5622            }
5623            else
5624                ++__first1;
5625            ++__first2;
5626        }
5627    }
5628    return _VSTD::copy(__first2, __last2, __result);
5629}
5630
5631template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5632inline _LIBCPP_INLINE_VISIBILITY
5633_OutputIterator
5634set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5635                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5636{
5637#ifdef _LIBCPP_DEBUG
5638    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5639    __debug_less<_Compare> __c(__comp);
5640    return __set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __c);
5641#else  // _LIBCPP_DEBUG
5642    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5643    return __set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5644#endif  // _LIBCPP_DEBUG
5645}
5646
5647template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5648inline _LIBCPP_INLINE_VISIBILITY
5649_OutputIterator
5650set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5651                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5652{
5653    return _VSTD::set_symmetric_difference(__first1, __last1, __first2, __last2, __result,
5654                                          __less<typename iterator_traits<_InputIterator1>::value_type,
5655                                                 typename iterator_traits<_InputIterator2>::value_type>());
5656}
5657
5658// lexicographical_compare
5659
5660template <class _Compare, class _InputIterator1, class _InputIterator2>
5661bool
5662__lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5663                          _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5664{
5665    for (; __first2 != __last2; ++__first1, (void) ++__first2)
5666    {
5667        if (__first1 == __last1 || __comp(*__first1, *__first2))
5668            return true;
5669        if (__comp(*__first2, *__first1))
5670            return false;
5671    }
5672    return false;
5673}
5674
5675template <class _InputIterator1, class _InputIterator2, class _Compare>
5676inline _LIBCPP_INLINE_VISIBILITY
5677bool
5678lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5679                        _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5680{
5681#ifdef _LIBCPP_DEBUG
5682    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5683    __debug_less<_Compare> __c(__comp);
5684    return __lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __c);
5685#else  // _LIBCPP_DEBUG
5686    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5687    return __lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5688#endif  // _LIBCPP_DEBUG
5689}
5690
5691template <class _InputIterator1, class _InputIterator2>
5692inline _LIBCPP_INLINE_VISIBILITY
5693bool
5694lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5695                        _InputIterator2 __first2, _InputIterator2 __last2)
5696{
5697    return _VSTD::lexicographical_compare(__first1, __last1, __first2, __last2,
5698                                         __less<typename iterator_traits<_InputIterator1>::value_type,
5699                                                typename iterator_traits<_InputIterator2>::value_type>());
5700}
5701
5702// next_permutation
5703
5704template <class _Compare, class _BidirectionalIterator>
5705bool
5706__next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5707{
5708    _BidirectionalIterator __i = __last;
5709    if (__first == __last || __first == --__i)
5710        return false;
5711    while (true)
5712    {
5713        _BidirectionalIterator __ip1 = __i;
5714        if (__comp(*--__i, *__ip1))
5715        {
5716            _BidirectionalIterator __j = __last;
5717            while (!__comp(*__i, *--__j))
5718                ;
5719            swap(*__i, *__j);
5720            _VSTD::reverse(__ip1, __last);
5721            return true;
5722        }
5723        if (__i == __first)
5724        {
5725            _VSTD::reverse(__first, __last);
5726            return false;
5727        }
5728    }
5729}
5730
5731template <class _BidirectionalIterator, class _Compare>
5732inline _LIBCPP_INLINE_VISIBILITY
5733bool
5734next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5735{
5736#ifdef _LIBCPP_DEBUG
5737    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5738    __debug_less<_Compare> __c(__comp);
5739    return __next_permutation<_Comp_ref>(__first, __last, __c);
5740#else  // _LIBCPP_DEBUG
5741    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5742    return __next_permutation<_Comp_ref>(__first, __last, __comp);
5743#endif  // _LIBCPP_DEBUG
5744}
5745
5746template <class _BidirectionalIterator>
5747inline _LIBCPP_INLINE_VISIBILITY
5748bool
5749next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5750{
5751    return _VSTD::next_permutation(__first, __last,
5752                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5753}
5754
5755// prev_permutation
5756
5757template <class _Compare, class _BidirectionalIterator>
5758bool
5759__prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5760{
5761    _BidirectionalIterator __i = __last;
5762    if (__first == __last || __first == --__i)
5763        return false;
5764    while (true)
5765    {
5766        _BidirectionalIterator __ip1 = __i;
5767        if (__comp(*__ip1, *--__i))
5768        {
5769            _BidirectionalIterator __j = __last;
5770            while (!__comp(*--__j, *__i))
5771                ;
5772            swap(*__i, *__j);
5773            _VSTD::reverse(__ip1, __last);
5774            return true;
5775        }
5776        if (__i == __first)
5777        {
5778            _VSTD::reverse(__first, __last);
5779            return false;
5780        }
5781    }
5782}
5783
5784template <class _BidirectionalIterator, class _Compare>
5785inline _LIBCPP_INLINE_VISIBILITY
5786bool
5787prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5788{
5789#ifdef _LIBCPP_DEBUG
5790    typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
5791    __debug_less<_Compare> __c(__comp);
5792    return __prev_permutation<_Comp_ref>(__first, __last, __c);
5793#else  // _LIBCPP_DEBUG
5794    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
5795    return __prev_permutation<_Comp_ref>(__first, __last, __comp);
5796#endif  // _LIBCPP_DEBUG
5797}
5798
5799template <class _BidirectionalIterator>
5800inline _LIBCPP_INLINE_VISIBILITY
5801bool
5802prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5803{
5804    return _VSTD::prev_permutation(__first, __last,
5805                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5806}
5807
5808_LIBCPP_END_NAMESPACE_STD
5809
5810_LIBCPP_POP_MACROS
5811
5812#endif  // _LIBCPP_ALGORITHM
5813