1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef _LIBCPP___ALGORITHM_SORT_H
10 #define _LIBCPP___ALGORITHM_SORT_H
11 
12 #include <__config>
13 #include <__algorithm/comp.h>
14 #include <__algorithm/comp_ref_type.h>
15 #include <__algorithm/min_element.h>
16 #include <__algorithm/partial_sort.h>
17 #include <__algorithm/unwrap_iter.h>
18 #include <__utility/swap.h>
19 #include <memory>
20 
21 #if defined(_LIBCPP_DEBUG_RANDOMIZE_UNSPECIFIED_STABILITY)
22 #  include <__algorithm/shuffle.h>
23 #endif
24 
25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26 #pragma GCC system_header
27 #endif
28 
29 _LIBCPP_BEGIN_NAMESPACE_STD
30 
31 // stable, 2-3 compares, 0-2 swaps
32 
33 template <class _Compare, class _ForwardIterator>
34 _LIBCPP_CONSTEXPR_AFTER_CXX11 unsigned
35 __sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
36 {
37     unsigned __r = 0;
38     if (!__c(*__y, *__x))          // if x <= y
39     {
40         if (!__c(*__z, *__y))      // if y <= z
41             return __r;            // x <= y && y <= z
42                                    // x <= y && y > z
43         swap(*__y, *__z);          // x <= z && y < z
44         __r = 1;
45         if (__c(*__y, *__x))       // if x > y
46         {
47             swap(*__x, *__y);      // x < y && y <= z
48             __r = 2;
49         }
50         return __r;                // x <= y && y < z
51     }
52     if (__c(*__z, *__y))           // x > y, if y > z
53     {
54         swap(*__x, *__z);          // x < y && y < z
55         __r = 1;
56         return __r;
57     }
58     swap(*__x, *__y);              // x > y && y <= z
59     __r = 1;                       // x < y && x <= z
60     if (__c(*__z, *__y))           // if y > z
61     {
62         swap(*__y, *__z);          // x <= y && y < z
63         __r = 2;
64     }
65     return __r;
66 }                                  // x <= y && y <= z
67 
68 // stable, 3-6 compares, 0-5 swaps
69 
70 template <class _Compare, class _ForwardIterator>
71 unsigned
72 __sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
73             _ForwardIterator __x4, _Compare __c)
74 {
75     unsigned __r = _VSTD::__sort3<_Compare>(__x1, __x2, __x3, __c);
76     if (__c(*__x4, *__x3))
77     {
78         swap(*__x3, *__x4);
79         ++__r;
80         if (__c(*__x3, *__x2))
81         {
82             swap(*__x2, *__x3);
83             ++__r;
84             if (__c(*__x2, *__x1))
85             {
86                 swap(*__x1, *__x2);
87                 ++__r;
88             }
89         }
90     }
91     return __r;
92 }
93 
94 // stable, 4-10 compares, 0-9 swaps
95 
96 template <class _Compare, class _ForwardIterator>
97 _LIBCPP_HIDDEN
98 unsigned
99 __sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
100             _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
101 {
102     unsigned __r = _VSTD::__sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
103     if (__c(*__x5, *__x4))
104     {
105         swap(*__x4, *__x5);
106         ++__r;
107         if (__c(*__x4, *__x3))
108         {
109             swap(*__x3, *__x4);
110             ++__r;
111             if (__c(*__x3, *__x2))
112             {
113                 swap(*__x2, *__x3);
114                 ++__r;
115                 if (__c(*__x2, *__x1))
116                 {
117                     swap(*__x1, *__x2);
118                     ++__r;
119                 }
120             }
121         }
122     }
123     return __r;
124 }
125 
126 // Assumes size > 0
127 template <class _Compare, class _BidirectionalIterator>
128 _LIBCPP_CONSTEXPR_AFTER_CXX11 void
129 __selection_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
130 {
131     _BidirectionalIterator __lm1 = __last;
132     for (--__lm1; __first != __lm1; ++__first)
133     {
134         _BidirectionalIterator __i = _VSTD::min_element<_BidirectionalIterator, _Compare&>(__first, __last, __comp);
135         if (__i != __first)
136             swap(*__first, *__i);
137     }
138 }
139 
140 template <class _Compare, class _BidirectionalIterator>
141 void
142 __insertion_sort(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
143 {
144     typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
145     if (__first != __last)
146     {
147         _BidirectionalIterator __i = __first;
148         for (++__i; __i != __last; ++__i)
149         {
150             _BidirectionalIterator __j = __i;
151             value_type __t(_VSTD::move(*__j));
152             for (_BidirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
153                 *__j = _VSTD::move(*__k);
154             *__j = _VSTD::move(__t);
155         }
156     }
157 }
158 
159 template <class _Compare, class _RandomAccessIterator>
160 void
161 __insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
162 {
163     typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
164     _RandomAccessIterator __j = __first+2;
165     _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
166     for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
167     {
168         if (__comp(*__i, *__j))
169         {
170             value_type __t(_VSTD::move(*__i));
171             _RandomAccessIterator __k = __j;
172             __j = __i;
173             do
174             {
175                 *__j = _VSTD::move(*__k);
176                 __j = __k;
177             } while (__j != __first && __comp(__t, *--__k));
178             *__j = _VSTD::move(__t);
179         }
180         __j = __i;
181     }
182 }
183 
184 template <class _Compare, class _RandomAccessIterator>
185 bool
186 __insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
187 {
188     switch (__last - __first)
189     {
190     case 0:
191     case 1:
192         return true;
193     case 2:
194         if (__comp(*--__last, *__first))
195             swap(*__first, *__last);
196         return true;
197     case 3:
198         _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
199         return true;
200     case 4:
201         _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
202         return true;
203     case 5:
204         _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
205         return true;
206     }
207     typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
208     _RandomAccessIterator __j = __first+2;
209     _VSTD::__sort3<_Compare>(__first, __first+1, __j, __comp);
210     const unsigned __limit = 8;
211     unsigned __count = 0;
212     for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
213     {
214         if (__comp(*__i, *__j))
215         {
216             value_type __t(_VSTD::move(*__i));
217             _RandomAccessIterator __k = __j;
218             __j = __i;
219             do
220             {
221                 *__j = _VSTD::move(*__k);
222                 __j = __k;
223             } while (__j != __first && __comp(__t, *--__k));
224             *__j = _VSTD::move(__t);
225             if (++__count == __limit)
226                 return ++__i == __last;
227         }
228         __j = __i;
229     }
230     return true;
231 }
232 
233 template <class _Compare, class _BidirectionalIterator>
234 void
235 __insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
236                       typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp)
237 {
238     typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
239     if (__first1 != __last1)
240     {
241         __destruct_n __d(0);
242         unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
243         value_type* __last2 = __first2;
244         ::new ((void*)__last2) value_type(_VSTD::move(*__first1));
245         __d.template __incr<value_type>();
246         for (++__last2; ++__first1 != __last1; ++__last2)
247         {
248             value_type* __j2 = __last2;
249             value_type* __i2 = __j2;
250             if (__comp(*__first1, *--__i2))
251             {
252                 ::new ((void*)__j2) value_type(_VSTD::move(*__i2));
253                 __d.template __incr<value_type>();
254                 for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
255                     *__j2 = _VSTD::move(*__i2);
256                 *__j2 = _VSTD::move(*__first1);
257             }
258             else
259             {
260                 ::new ((void*)__j2) value_type(_VSTD::move(*__first1));
261                 __d.template __incr<value_type>();
262             }
263         }
264         __h.release();
265     }
266 }
267 
268 template <class _Compare, class _RandomAccessIterator>
269 void
270 __introsort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
271             typename _VSTD::iterator_traits<_RandomAccessIterator>::difference_type __depth)
272 {
273     typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
274     typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
275     const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
276                                     is_trivially_copy_assignable<value_type>::value ? 30 : 6;
277     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
278     while (true)
279     {
280     __restart:
281         difference_type __len = __last - __first;
282         switch (__len)
283         {
284         case 0:
285         case 1:
286             return;
287         case 2:
288             if (__comp(*--__last, *__first))
289                 swap(*__first, *__last);
290             return;
291         case 3:
292             _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
293             return;
294         case 4:
295             _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
296             return;
297         case 5:
298             _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
299             return;
300         }
301         if (__len <= __limit)
302         {
303             _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
304             return;
305         }
306         // __len > 5
307         if (__depth == 0)
308         {
309           // Fallback to heap sort as Introsort suggests.
310           _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
311           return;
312         }
313         --__depth;
314         _RandomAccessIterator __m = __first;
315         _RandomAccessIterator __lm1 = __last;
316         --__lm1;
317         unsigned __n_swaps;
318         {
319         difference_type __delta;
320         if (__len >= 1000)
321         {
322             __delta = __len/2;
323             __m += __delta;
324             __delta /= 2;
325             __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
326         }
327         else
328         {
329             __delta = __len/2;
330             __m += __delta;
331             __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
332         }
333         }
334         // *__m is median
335         // partition [__first, __m) < *__m and *__m <= [__m, __last)
336         // (this inhibits tossing elements equivalent to __m around unnecessarily)
337         _RandomAccessIterator __i = __first;
338         _RandomAccessIterator __j = __lm1;
339         // j points beyond range to be tested, *__m is known to be <= *__lm1
340         // The search going up is known to be guarded but the search coming down isn't.
341         // Prime the downward search with a guard.
342         if (!__comp(*__i, *__m))  // if *__first == *__m
343         {
344             // *__first == *__m, *__first doesn't go in first part
345             // manually guard downward moving __j against __i
346             while (true)
347             {
348                 if (__i == --__j)
349                 {
350                     // *__first == *__m, *__m <= all other elements
351                     // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
352                     ++__i;  // __first + 1
353                     __j = __last;
354                     if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
355                     {
356                         while (true)
357                         {
358                             if (__i == __j)
359                                 return;  // [__first, __last) all equivalent elements
360                             if (__comp(*__first, *__i))
361                             {
362                                 swap(*__i, *__j);
363                                 ++__n_swaps;
364                                 ++__i;
365                                 break;
366                             }
367                             ++__i;
368                         }
369                     }
370                     // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
371                     if (__i == __j)
372                         return;
373                     while (true)
374                     {
375                         while (!__comp(*__first, *__i))
376                             ++__i;
377                         while (__comp(*__first, *--__j))
378                             ;
379                         if (__i >= __j)
380                             break;
381                         swap(*__i, *__j);
382                         ++__n_swaps;
383                         ++__i;
384                     }
385                     // [__first, __i) == *__first and *__first < [__i, __last)
386                     // The first part is sorted, sort the second part
387                     // _VSTD::__sort<_Compare>(__i, __last, __comp);
388                     __first = __i;
389                     goto __restart;
390                 }
391                 if (__comp(*__j, *__m))
392                 {
393                     swap(*__i, *__j);
394                     ++__n_swaps;
395                     break;  // found guard for downward moving __j, now use unguarded partition
396                 }
397             }
398         }
399         // It is known that *__i < *__m
400         ++__i;
401         // j points beyond range to be tested, *__m is known to be <= *__lm1
402         // if not yet partitioned...
403         if (__i < __j)
404         {
405             // known that *(__i - 1) < *__m
406             // known that __i <= __m
407             while (true)
408             {
409                 // __m still guards upward moving __i
410                 while (__comp(*__i, *__m))
411                     ++__i;
412                 // It is now known that a guard exists for downward moving __j
413                 while (!__comp(*--__j, *__m))
414                     ;
415                 if (__i > __j)
416                     break;
417                 swap(*__i, *__j);
418                 ++__n_swaps;
419                 // It is known that __m != __j
420                 // If __m just moved, follow it
421                 if (__m == __i)
422                     __m = __j;
423                 ++__i;
424             }
425         }
426         // [__first, __i) < *__m and *__m <= [__i, __last)
427         if (__i != __m && __comp(*__m, *__i))
428         {
429             swap(*__i, *__m);
430             ++__n_swaps;
431         }
432         // [__first, __i) < *__i and *__i <= [__i+1, __last)
433         // If we were given a perfect partition, see if insertion sort is quick...
434         if (__n_swaps == 0)
435         {
436             bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
437             if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
438             {
439                 if (__fs)
440                     return;
441                 __last = __i;
442                 continue;
443             }
444             else
445             {
446                 if (__fs)
447                 {
448                     __first = ++__i;
449                     continue;
450                 }
451             }
452         }
453         // sort smaller range with recursive call and larger with tail recursion elimination
454         if (__i - __first < __last - __i)
455         {
456           _VSTD::__introsort<_Compare>(__first, __i, __comp, __depth);
457           __first = ++__i;
458         }
459         else
460         {
461           _VSTD::__introsort<_Compare>(__i + 1, __last, __comp, __depth);
462           __last = __i;
463         }
464     }
465 }
466 
467 template <typename _Number>
468 inline _LIBCPP_HIDE_FROM_ABI _Number __log2i(_Number __n) {
469   _Number __log2 = 0;
470   while (__n > 1) {
471     __log2++;
472     __n >>= 1;
473   }
474   return __log2;
475 }
476 
477 template <class _Compare, class _RandomAccessIterator>
478 void __sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
479   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
480   difference_type __depth_limit = 2 * __log2i(__last - __first);
481   __introsort(__first, __last, __comp, __depth_limit);
482 }
483 
484 template <class _Compare, class _Tp>
485 inline _LIBCPP_INLINE_VISIBILITY
486 void
487 __sort(_Tp** __first, _Tp** __last, __less<_Tp*>&)
488 {
489     __less<uintptr_t> __comp;
490     _VSTD::__sort<__less<uintptr_t>&, uintptr_t*>((uintptr_t*)__first, (uintptr_t*)__last, __comp);
491 }
492 
493 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
494 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
495 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
496 #endif
497 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
498 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
499 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
500 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
501 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
502 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
503 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
504 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
505 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
506 _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>&))
507 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
508 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
509 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
510 
511 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
512 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
513 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
514 #endif
515 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
516 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
517 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
518 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
519 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
520 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
521 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
522 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
523 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
524 _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>&))
525 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
526 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
527 _LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
528 
529 _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>&))
530 
531 template <class _RandomAccessIterator, class _Compare>
532 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
533 void
534 sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
535 {
536   _LIBCPP_DEBUG_RANDOMIZE_RANGE(__first, __last);
537   typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
538   if (__libcpp_is_constant_evaluated()) {
539     _VSTD::__partial_sort<_Comp_ref>(__first, __last, __last, _Comp_ref(__comp));
540   } else {
541     _VSTD::__sort<_Comp_ref>(_VSTD::__unwrap_iter(__first), _VSTD::__unwrap_iter(__last), _Comp_ref(__comp));
542   }
543 }
544 
545 template <class _RandomAccessIterator>
546 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
547 void
548 sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
549 {
550     _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
551 }
552 
553 _LIBCPP_END_NAMESPACE_STD
554 
555 #endif // _LIBCPP___ALGORITHM_SORT_H
556