libstdc++
stl_algobase.h
Go to the documentation of this file.
1 // Core algorithmic facilities -*- C++ -*-
2 
3 // Copyright (C) 2001-2022 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /*
26  *
27  * Copyright (c) 1994
28  * Hewlett-Packard Company
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation. Hewlett-Packard Company makes no
35  * representations about the suitability of this software for any
36  * purpose. It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1996-1998
40  * Silicon Graphics Computer Systems, Inc.
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation. Silicon Graphics makes no
47  * representations about the suitability of this software for any
48  * purpose. It is provided "as is" without express or implied warranty.
49  */
50 
51 /** @file bits/stl_algobase.h
52  * This is an internal header file, included by other library headers.
53  * Do not attempt to use it directly. @headername{algorithm}
54  */
55 
56 #ifndef _STL_ALGOBASE_H
57 #define _STL_ALGOBASE_H 1
58 
59 #include <bits/c++config.h>
60 #include <bits/functexcept.h>
61 #include <bits/cpp_type_traits.h>
62 #include <ext/type_traits.h>
63 #include <ext/numeric_traits.h>
64 #include <bits/stl_pair.h>
65 #include <bits/stl_iterator_base_types.h>
66 #include <bits/stl_iterator_base_funcs.h>
67 #include <bits/stl_iterator.h>
68 #include <bits/concept_check.h>
69 #include <debug/debug.h>
70 #include <bits/move.h> // For std::swap
71 #include <bits/predefined_ops.h>
72 #if __cplusplus >= 201103L
73 # include <type_traits>
74 #endif
75 #if __cplusplus > 201703L
76 # include <compare>
77 #endif
78 
79 namespace std _GLIBCXX_VISIBILITY(default)
80 {
81 _GLIBCXX_BEGIN_NAMESPACE_VERSION
82 
83  /*
84  * A constexpr wrapper for __builtin_memcmp.
85  * @param __num The number of elements of type _Tp (not bytes).
86  */
87  template<typename _Tp, typename _Up>
88  _GLIBCXX14_CONSTEXPR
89  inline int
90  __memcmp(const _Tp* __first1, const _Up* __first2, size_t __num)
91  {
92 #if __cplusplus >= 201103L
93  static_assert(sizeof(_Tp) == sizeof(_Up), "can be compared with memcmp");
94 #endif
95 #ifdef __cpp_lib_is_constant_evaluated
96  if (std::is_constant_evaluated())
97  {
98  for(; __num > 0; ++__first1, ++__first2, --__num)
99  if (*__first1 != *__first2)
100  return *__first1 < *__first2 ? -1 : 1;
101  return 0;
102  }
103  else
104 #endif
105  return __builtin_memcmp(__first1, __first2, sizeof(_Tp) * __num);
106  }
107 
108 #if __cplusplus < 201103L
109  // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
110  // nutshell, we are partially implementing the resolution of DR 187,
111  // when it's safe, i.e., the value_types are equal.
112  template<bool _BoolType>
113  struct __iter_swap
114  {
115  template<typename _ForwardIterator1, typename _ForwardIterator2>
116  static void
117  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
118  {
119  typedef typename iterator_traits<_ForwardIterator1>::value_type
120  _ValueType1;
121  _ValueType1 __tmp = *__a;
122  *__a = *__b;
123  *__b = __tmp;
124  }
125  };
126 
127  template<>
128  struct __iter_swap<true>
129  {
130  template<typename _ForwardIterator1, typename _ForwardIterator2>
131  static void
132  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
133  {
134  swap(*__a, *__b);
135  }
136  };
137 #endif // C++03
138 
139  /**
140  * @brief Swaps the contents of two iterators.
141  * @ingroup mutating_algorithms
142  * @param __a An iterator.
143  * @param __b Another iterator.
144  * @return Nothing.
145  *
146  * This function swaps the values pointed to by two iterators, not the
147  * iterators themselves.
148  */
149  template<typename _ForwardIterator1, typename _ForwardIterator2>
150  _GLIBCXX20_CONSTEXPR
151  inline void
152  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
153  {
154  // concept requirements
155  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
156  _ForwardIterator1>)
157  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
158  _ForwardIterator2>)
159 
160 #if __cplusplus < 201103L
161  typedef typename iterator_traits<_ForwardIterator1>::value_type
162  _ValueType1;
163  typedef typename iterator_traits<_ForwardIterator2>::value_type
164  _ValueType2;
165 
166  __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
167  _ValueType2>)
168  __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
169  _ValueType1>)
170 
171  typedef typename iterator_traits<_ForwardIterator1>::reference
172  _ReferenceType1;
173  typedef typename iterator_traits<_ForwardIterator2>::reference
174  _ReferenceType2;
175  std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
176  && __are_same<_ValueType1&, _ReferenceType1>::__value
177  && __are_same<_ValueType2&, _ReferenceType2>::__value>::
178  iter_swap(__a, __b);
179 #else
180  // _GLIBCXX_RESOLVE_LIB_DEFECTS
181  // 187. iter_swap underspecified
182  swap(*__a, *__b);
183 #endif
184  }
185 
186  /**
187  * @brief Swap the elements of two sequences.
188  * @ingroup mutating_algorithms
189  * @param __first1 A forward iterator.
190  * @param __last1 A forward iterator.
191  * @param __first2 A forward iterator.
192  * @return An iterator equal to @p first2+(last1-first1).
193  *
194  * Swaps each element in the range @p [first1,last1) with the
195  * corresponding element in the range @p [first2,(last1-first1)).
196  * The ranges must not overlap.
197  */
198  template<typename _ForwardIterator1, typename _ForwardIterator2>
199  _GLIBCXX20_CONSTEXPR
200  _ForwardIterator2
201  swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
202  _ForwardIterator2 __first2)
203  {
204  // concept requirements
205  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
206  _ForwardIterator1>)
207  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
208  _ForwardIterator2>)
209  __glibcxx_requires_valid_range(__first1, __last1);
210 
211  for (; __first1 != __last1; ++__first1, (void)++__first2)
212  std::iter_swap(__first1, __first2);
213  return __first2;
214  }
215 
216  /**
217  * @brief This does what you think it does.
218  * @ingroup sorting_algorithms
219  * @param __a A thing of arbitrary type.
220  * @param __b Another thing of arbitrary type.
221  * @return The lesser of the parameters.
222  *
223  * This is the simple classic generic implementation. It will work on
224  * temporary expressions, since they are only evaluated once, unlike a
225  * preprocessor macro.
226  */
227  template<typename _Tp>
228  _GLIBCXX14_CONSTEXPR
229  inline const _Tp&
230  min(const _Tp& __a, const _Tp& __b)
231  {
232  // concept requirements
233  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
234  //return __b < __a ? __b : __a;
235  if (__b < __a)
236  return __b;
237  return __a;
238  }
239 
240  /**
241  * @brief This does what you think it does.
242  * @ingroup sorting_algorithms
243  * @param __a A thing of arbitrary type.
244  * @param __b Another thing of arbitrary type.
245  * @return The greater of the parameters.
246  *
247  * This is the simple classic generic implementation. It will work on
248  * temporary expressions, since they are only evaluated once, unlike a
249  * preprocessor macro.
250  */
251  template<typename _Tp>
252  _GLIBCXX14_CONSTEXPR
253  inline const _Tp&
254  max(const _Tp& __a, const _Tp& __b)
255  {
256  // concept requirements
257  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
258  //return __a < __b ? __b : __a;
259  if (__a < __b)
260  return __b;
261  return __a;
262  }
263 
264  /**
265  * @brief This does what you think it does.
266  * @ingroup sorting_algorithms
267  * @param __a A thing of arbitrary type.
268  * @param __b Another thing of arbitrary type.
269  * @param __comp A @link comparison_functors comparison functor@endlink.
270  * @return The lesser of the parameters.
271  *
272  * This will work on temporary expressions, since they are only evaluated
273  * once, unlike a preprocessor macro.
274  */
275  template<typename _Tp, typename _Compare>
276  _GLIBCXX14_CONSTEXPR
277  inline const _Tp&
278  min(const _Tp& __a, const _Tp& __b, _Compare __comp)
279  {
280  //return __comp(__b, __a) ? __b : __a;
281  if (__comp(__b, __a))
282  return __b;
283  return __a;
284  }
285 
286  /**
287  * @brief This does what you think it does.
288  * @ingroup sorting_algorithms
289  * @param __a A thing of arbitrary type.
290  * @param __b Another thing of arbitrary type.
291  * @param __comp A @link comparison_functors comparison functor@endlink.
292  * @return The greater of the parameters.
293  *
294  * This will work on temporary expressions, since they are only evaluated
295  * once, unlike a preprocessor macro.
296  */
297  template<typename _Tp, typename _Compare>
298  _GLIBCXX14_CONSTEXPR
299  inline const _Tp&
300  max(const _Tp& __a, const _Tp& __b, _Compare __comp)
301  {
302  //return __comp(__a, __b) ? __b : __a;
303  if (__comp(__a, __b))
304  return __b;
305  return __a;
306  }
307 
308  // Fallback implementation of the function in bits/stl_iterator.h used to
309  // remove the __normal_iterator wrapper. See copy, fill, ...
310  template<typename _Iterator>
311  _GLIBCXX20_CONSTEXPR
312  inline _Iterator
313  __niter_base(_Iterator __it)
314  _GLIBCXX_NOEXCEPT_IF(std::is_nothrow_copy_constructible<_Iterator>::value)
315  { return __it; }
316 
317  template<typename _Ite, typename _Seq>
318  _Ite
319  __niter_base(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq,
320  std::random_access_iterator_tag>&);
321 
322  // Reverse the __niter_base transformation to get a
323  // __normal_iterator back again (this assumes that __normal_iterator
324  // is only used to wrap random access iterators, like pointers).
325  template<typename _From, typename _To>
326  _GLIBCXX20_CONSTEXPR
327  inline _From
328  __niter_wrap(_From __from, _To __res)
329  { return __from + (__res - std::__niter_base(__from)); }
330 
331  // No need to wrap, iterator already has the right type.
332  template<typename _Iterator>
333  _GLIBCXX20_CONSTEXPR
334  inline _Iterator
335  __niter_wrap(const _Iterator&, _Iterator __res)
336  { return __res; }
337 
338  // All of these auxiliary structs serve two purposes. (1) Replace
339  // calls to copy with memmove whenever possible. (Memmove, not memcpy,
340  // because the input and output ranges are permitted to overlap.)
341  // (2) If we're using random access iterators, then write the loop as
342  // a for loop with an explicit count.
343 
344  template<bool _IsMove, bool _IsSimple, typename _Category>
345  struct __copy_move
346  {
347  template<typename _II, typename _OI>
348  _GLIBCXX20_CONSTEXPR
349  static _OI
350  __copy_m(_II __first, _II __last, _OI __result)
351  {
352  for (; __first != __last; ++__result, (void)++__first)
353  *__result = *__first;
354  return __result;
355  }
356  };
357 
358 #if __cplusplus >= 201103L
359  template<typename _Category>
360  struct __copy_move<true, false, _Category>
361  {
362  template<typename _II, typename _OI>
363  _GLIBCXX20_CONSTEXPR
364  static _OI
365  __copy_m(_II __first, _II __last, _OI __result)
366  {
367  for (; __first != __last; ++__result, (void)++__first)
368  *__result = std::move(*__first);
369  return __result;
370  }
371  };
372 #endif
373 
374  template<>
375  struct __copy_move<false, false, random_access_iterator_tag>
376  {
377  template<typename _II, typename _OI>
378  _GLIBCXX20_CONSTEXPR
379  static _OI
380  __copy_m(_II __first, _II __last, _OI __result)
381  {
382  typedef typename iterator_traits<_II>::difference_type _Distance;
383  for(_Distance __n = __last - __first; __n > 0; --__n)
384  {
385  *__result = *__first;
386  ++__first;
387  ++__result;
388  }
389  return __result;
390  }
391 
392  template<typename _Tp, typename _Up>
393  static void
394  __assign_one(_Tp* __to, _Up* __from)
395  { *__to = *__from; }
396  };
397 
398 #if __cplusplus >= 201103L
399  template<>
400  struct __copy_move<true, false, random_access_iterator_tag>
401  {
402  template<typename _II, typename _OI>
403  _GLIBCXX20_CONSTEXPR
404  static _OI
405  __copy_m(_II __first, _II __last, _OI __result)
406  {
407  typedef typename iterator_traits<_II>::difference_type _Distance;
408  for(_Distance __n = __last - __first; __n > 0; --__n)
409  {
410  *__result = std::move(*__first);
411  ++__first;
412  ++__result;
413  }
414  return __result;
415  }
416 
417  template<typename _Tp, typename _Up>
418  static void
419  __assign_one(_Tp* __to, _Up* __from)
420  { *__to = std::move(*__from); }
421  };
422 #endif
423 
424  template<bool _IsMove>
425  struct __copy_move<_IsMove, true, random_access_iterator_tag>
426  {
427  template<typename _Tp, typename _Up>
428  _GLIBCXX20_CONSTEXPR
429  static _Up*
430  __copy_m(_Tp* __first, _Tp* __last, _Up* __result)
431  {
432  const ptrdiff_t _Num = __last - __first;
433  if (__builtin_expect(_Num > 1, true))
434  __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
435  else if (_Num == 1)
436  std::__copy_move<_IsMove, false, random_access_iterator_tag>::
437  __assign_one(__result, __first);
438  return __result + _Num;
439  }
440  };
441 
442 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
443 
444  template<typename _Tp, typename _Ref, typename _Ptr>
445  struct _Deque_iterator;
446 
447  struct _Bit_iterator;
448 
449 _GLIBCXX_END_NAMESPACE_CONTAINER
450 
451  // Helpers for streambuf iterators (either istream or ostream).
452  // NB: avoid including <iosfwd>, relatively large.
453  template<typename _CharT>
454  struct char_traits;
455 
456  template<typename _CharT, typename _Traits>
457  class istreambuf_iterator;
458 
459  template<typename _CharT, typename _Traits>
460  class ostreambuf_iterator;
461 
462  template<bool _IsMove, typename _CharT>
463  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
464  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
465  __copy_move_a2(_CharT*, _CharT*,
466  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
467 
468  template<bool _IsMove, typename _CharT>
469  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
470  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
471  __copy_move_a2(const _CharT*, const _CharT*,
472  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
473 
474  template<bool _IsMove, typename _CharT>
475  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
476  _CharT*>::__type
477  __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
478  istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
479 
480  template<bool _IsMove, typename _CharT>
481  typename __gnu_cxx::__enable_if<
482  __is_char<_CharT>::__value,
483  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
484  __copy_move_a2(
485  istreambuf_iterator<_CharT, char_traits<_CharT> >,
486  istreambuf_iterator<_CharT, char_traits<_CharT> >,
487  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>);
488 
489  template<bool _IsMove, typename _II, typename _OI>
490  _GLIBCXX20_CONSTEXPR
491  inline _OI
492  __copy_move_a2(_II __first, _II __last, _OI __result)
493  {
494  typedef typename iterator_traits<_II>::iterator_category _Category;
495 #ifdef __cpp_lib_is_constant_evaluated
496  if (std::is_constant_evaluated())
497  return std::__copy_move<_IsMove, false, _Category>::
498  __copy_m(__first, __last, __result);
499 #endif
500  return std::__copy_move<_IsMove, __memcpyable<_OI, _II>::__value,
501  _Category>::__copy_m(__first, __last, __result);
502  }
503 
504  template<bool _IsMove,
505  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
506  _OI
507  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
508  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
509  _OI);
510 
511  template<bool _IsMove,
512  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
513  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
514  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
515  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
516  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
517 
518  template<bool _IsMove, typename _II, typename _Tp>
519  typename __gnu_cxx::__enable_if<
520  __is_random_access_iter<_II>::__value,
521  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
522  __copy_move_a1(_II, _II, _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
523 
524  template<bool _IsMove, typename _II, typename _OI>
525  _GLIBCXX20_CONSTEXPR
526  inline _OI
527  __copy_move_a1(_II __first, _II __last, _OI __result)
528  { return std::__copy_move_a2<_IsMove>(__first, __last, __result); }
529 
530  template<bool _IsMove, typename _II, typename _OI>
531  _GLIBCXX20_CONSTEXPR
532  inline _OI
533  __copy_move_a(_II __first, _II __last, _OI __result)
534  {
535  return std::__niter_wrap(__result,
536  std::__copy_move_a1<_IsMove>(std::__niter_base(__first),
537  std::__niter_base(__last),
538  std::__niter_base(__result)));
539  }
540 
541  template<bool _IsMove,
542  typename _Ite, typename _Seq, typename _Cat, typename _OI>
543  _OI
544  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
545  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
546  _OI);
547 
548  template<bool _IsMove,
549  typename _II, typename _Ite, typename _Seq, typename _Cat>
550  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
551  __copy_move_a(_II, _II,
552  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
553 
554  template<bool _IsMove,
555  typename _IIte, typename _ISeq, typename _ICat,
556  typename _OIte, typename _OSeq, typename _OCat>
557  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
558  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
559  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
560  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
561 
562  template<typename _InputIterator, typename _Size, typename _OutputIterator>
563  _GLIBCXX20_CONSTEXPR
564  _OutputIterator
565  __copy_n_a(_InputIterator __first, _Size __n, _OutputIterator __result,
566  bool)
567  {
568  if (__n > 0)
569  {
570  while (true)
571  {
572  *__result = *__first;
573  ++__result;
574  if (--__n > 0)
575  ++__first;
576  else
577  break;
578  }
579  }
580  return __result;
581  }
582 
583  template<typename _CharT, typename _Size>
584  typename __gnu_cxx::__enable_if<
585  __is_char<_CharT>::__value, _CharT*>::__type
586  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >,
587  _Size, _CharT*, bool);
588 
589  template<typename _CharT, typename _Size>
590  typename __gnu_cxx::__enable_if<
591  __is_char<_CharT>::__value,
592  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
593  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >, _Size,
594  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>,
595  bool);
596 
597  /**
598  * @brief Copies the range [first,last) into result.
599  * @ingroup mutating_algorithms
600  * @param __first An input iterator.
601  * @param __last An input iterator.
602  * @param __result An output iterator.
603  * @return result + (last - first)
604  *
605  * This inline function will boil down to a call to @c memmove whenever
606  * possible. Failing that, if random access iterators are passed, then the
607  * loop count will be known (and therefore a candidate for compiler
608  * optimizations such as unrolling). Result may not be contained within
609  * [first,last); the copy_backward function should be used instead.
610  *
611  * Note that the end of the output range is permitted to be contained
612  * within [first,last).
613  */
614  template<typename _II, typename _OI>
615  _GLIBCXX20_CONSTEXPR
616  inline _OI
617  copy(_II __first, _II __last, _OI __result)
618  {
619  // concept requirements
620  __glibcxx_function_requires(_InputIteratorConcept<_II>)
621  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
622  typename iterator_traits<_II>::reference>)
623  __glibcxx_requires_can_increment_range(__first, __last, __result);
624 
625  return std::__copy_move_a<__is_move_iterator<_II>::__value>
626  (std::__miter_base(__first), std::__miter_base(__last), __result);
627  }
628 
629 #if __cplusplus >= 201103L
630  /**
631  * @brief Moves the range [first,last) into result.
632  * @ingroup mutating_algorithms
633  * @param __first An input iterator.
634  * @param __last An input iterator.
635  * @param __result An output iterator.
636  * @return result + (last - first)
637  *
638  * This inline function will boil down to a call to @c memmove whenever
639  * possible. Failing that, if random access iterators are passed, then the
640  * loop count will be known (and therefore a candidate for compiler
641  * optimizations such as unrolling). Result may not be contained within
642  * [first,last); the move_backward function should be used instead.
643  *
644  * Note that the end of the output range is permitted to be contained
645  * within [first,last).
646  */
647  template<typename _II, typename _OI>
648  _GLIBCXX20_CONSTEXPR
649  inline _OI
650  move(_II __first, _II __last, _OI __result)
651  {
652  // concept requirements
653  __glibcxx_function_requires(_InputIteratorConcept<_II>)
654  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
655  typename iterator_traits<_II>::value_type&&>)
656  __glibcxx_requires_can_increment_range(__first, __last, __result);
657 
658  return std::__copy_move_a<true>(std::__miter_base(__first),
659  std::__miter_base(__last), __result);
660  }
661 
662 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
663 #else
664 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
665 #endif
666 
667  template<bool _IsMove, bool _IsSimple, typename _Category>
668  struct __copy_move_backward
669  {
670  template<typename _BI1, typename _BI2>
671  _GLIBCXX20_CONSTEXPR
672  static _BI2
673  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
674  {
675  while (__first != __last)
676  *--__result = *--__last;
677  return __result;
678  }
679  };
680 
681 #if __cplusplus >= 201103L
682  template<typename _Category>
683  struct __copy_move_backward<true, false, _Category>
684  {
685  template<typename _BI1, typename _BI2>
686  _GLIBCXX20_CONSTEXPR
687  static _BI2
688  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
689  {
690  while (__first != __last)
691  *--__result = std::move(*--__last);
692  return __result;
693  }
694  };
695 #endif
696 
697  template<>
698  struct __copy_move_backward<false, false, random_access_iterator_tag>
699  {
700  template<typename _BI1, typename _BI2>
701  _GLIBCXX20_CONSTEXPR
702  static _BI2
703  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
704  {
705  typename iterator_traits<_BI1>::difference_type
706  __n = __last - __first;
707  for (; __n > 0; --__n)
708  *--__result = *--__last;
709  return __result;
710  }
711  };
712 
713 #if __cplusplus >= 201103L
714  template<>
715  struct __copy_move_backward<true, false, random_access_iterator_tag>
716  {
717  template<typename _BI1, typename _BI2>
718  _GLIBCXX20_CONSTEXPR
719  static _BI2
720  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
721  {
722  typename iterator_traits<_BI1>::difference_type
723  __n = __last - __first;
724  for (; __n > 0; --__n)
725  *--__result = std::move(*--__last);
726  return __result;
727  }
728  };
729 #endif
730 
731  template<bool _IsMove>
732  struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
733  {
734  template<typename _Tp, typename _Up>
735  _GLIBCXX20_CONSTEXPR
736  static _Up*
737  __copy_move_b(_Tp* __first, _Tp* __last, _Up* __result)
738  {
739  const ptrdiff_t _Num = __last - __first;
740  if (__builtin_expect(_Num > 1, true))
741  __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
742  else if (_Num == 1)
743  std::__copy_move<_IsMove, false, random_access_iterator_tag>::
744  __assign_one(__result - 1, __first);
745  return __result - _Num;
746  }
747  };
748 
749  template<bool _IsMove, typename _BI1, typename _BI2>
750  _GLIBCXX20_CONSTEXPR
751  inline _BI2
752  __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
753  {
754  typedef typename iterator_traits<_BI1>::iterator_category _Category;
755 #ifdef __cpp_lib_is_constant_evaluated
756  if (std::is_constant_evaluated())
757  return std::__copy_move_backward<_IsMove, false, _Category>::
758  __copy_move_b(__first, __last, __result);
759 #endif
760  return std::__copy_move_backward<_IsMove,
761  __memcpyable<_BI2, _BI1>::__value,
762  _Category>::__copy_move_b(__first,
763  __last,
764  __result);
765  }
766 
767  template<bool _IsMove, typename _BI1, typename _BI2>
768  _GLIBCXX20_CONSTEXPR
769  inline _BI2
770  __copy_move_backward_a1(_BI1 __first, _BI1 __last, _BI2 __result)
771  { return std::__copy_move_backward_a2<_IsMove>(__first, __last, __result); }
772 
773  template<bool _IsMove,
774  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
775  _OI
776  __copy_move_backward_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
777  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
778  _OI);
779 
780  template<bool _IsMove,
781  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
782  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
783  __copy_move_backward_a1(
784  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
785  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
786  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
787 
788  template<bool _IsMove, typename _II, typename _Tp>
789  typename __gnu_cxx::__enable_if<
790  __is_random_access_iter<_II>::__value,
791  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
792  __copy_move_backward_a1(_II, _II,
793  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
794 
795  template<bool _IsMove, typename _II, typename _OI>
796  _GLIBCXX20_CONSTEXPR
797  inline _OI
798  __copy_move_backward_a(_II __first, _II __last, _OI __result)
799  {
800  return std::__niter_wrap(__result,
801  std::__copy_move_backward_a1<_IsMove>
802  (std::__niter_base(__first), std::__niter_base(__last),
803  std::__niter_base(__result)));
804  }
805 
806  template<bool _IsMove,
807  typename _Ite, typename _Seq, typename _Cat, typename _OI>
808  _OI
809  __copy_move_backward_a(
810  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
811  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
812  _OI);
813 
814  template<bool _IsMove,
815  typename _II, typename _Ite, typename _Seq, typename _Cat>
816  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
817  __copy_move_backward_a(_II, _II,
818  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
819 
820  template<bool _IsMove,
821  typename _IIte, typename _ISeq, typename _ICat,
822  typename _OIte, typename _OSeq, typename _OCat>
823  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
824  __copy_move_backward_a(
825  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
826  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
827  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
828 
829  /**
830  * @brief Copies the range [first,last) into result.
831  * @ingroup mutating_algorithms
832  * @param __first A bidirectional iterator.
833  * @param __last A bidirectional iterator.
834  * @param __result A bidirectional iterator.
835  * @return result - (last - first)
836  *
837  * The function has the same effect as copy, but starts at the end of the
838  * range and works its way to the start, returning the start of the result.
839  * This inline function will boil down to a call to @c memmove whenever
840  * possible. Failing that, if random access iterators are passed, then the
841  * loop count will be known (and therefore a candidate for compiler
842  * optimizations such as unrolling).
843  *
844  * Result may not be in the range (first,last]. Use copy instead. Note
845  * that the start of the output range may overlap [first,last).
846  */
847  template<typename _BI1, typename _BI2>
848  _GLIBCXX20_CONSTEXPR
849  inline _BI2
850  copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
851  {
852  // concept requirements
853  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
854  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
855  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
856  typename iterator_traits<_BI1>::reference>)
857  __glibcxx_requires_can_decrement_range(__first, __last, __result);
858 
859  return std::__copy_move_backward_a<__is_move_iterator<_BI1>::__value>
860  (std::__miter_base(__first), std::__miter_base(__last), __result);
861  }
862 
863 #if __cplusplus >= 201103L
864  /**
865  * @brief Moves the range [first,last) into result.
866  * @ingroup mutating_algorithms
867  * @param __first A bidirectional iterator.
868  * @param __last A bidirectional iterator.
869  * @param __result A bidirectional iterator.
870  * @return result - (last - first)
871  *
872  * The function has the same effect as move, but starts at the end of the
873  * range and works its way to the start, returning the start of the result.
874  * This inline function will boil down to a call to @c memmove whenever
875  * possible. Failing that, if random access iterators are passed, then the
876  * loop count will be known (and therefore a candidate for compiler
877  * optimizations such as unrolling).
878  *
879  * Result may not be in the range (first,last]. Use move instead. Note
880  * that the start of the output range may overlap [first,last).
881  */
882  template<typename _BI1, typename _BI2>
883  _GLIBCXX20_CONSTEXPR
884  inline _BI2
885  move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
886  {
887  // concept requirements
888  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
889  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
890  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
891  typename iterator_traits<_BI1>::value_type&&>)
892  __glibcxx_requires_can_decrement_range(__first, __last, __result);
893 
894  return std::__copy_move_backward_a<true>(std::__miter_base(__first),
895  std::__miter_base(__last),
896  __result);
897  }
898 
899 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
900 #else
901 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
902 #endif
903 
904  template<typename _ForwardIterator, typename _Tp>
905  _GLIBCXX20_CONSTEXPR
906  inline typename
907  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
908  __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
909  const _Tp& __value)
910  {
911  for (; __first != __last; ++__first)
912  *__first = __value;
913  }
914 
915  template<typename _ForwardIterator, typename _Tp>
916  _GLIBCXX20_CONSTEXPR
917  inline typename
918  __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
919  __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
920  const _Tp& __value)
921  {
922  const _Tp __tmp = __value;
923  for (; __first != __last; ++__first)
924  *__first = __tmp;
925  }
926 
927  // Specialization: for char types we can use memset.
928  template<typename _Tp>
929  _GLIBCXX20_CONSTEXPR
930  inline typename
931  __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
932  __fill_a1(_Tp* __first, _Tp* __last, const _Tp& __c)
933  {
934  const _Tp __tmp = __c;
935 #if __cpp_lib_is_constant_evaluated
936  if (std::is_constant_evaluated())
937  {
938  for (; __first != __last; ++__first)
939  *__first = __tmp;
940  return;
941  }
942 #endif
943  if (const size_t __len = __last - __first)
944  __builtin_memset(__first, static_cast<unsigned char>(__tmp), __len);
945  }
946 
947  template<typename _Ite, typename _Cont, typename _Tp>
948  _GLIBCXX20_CONSTEXPR
949  inline void
950  __fill_a1(::__gnu_cxx::__normal_iterator<_Ite, _Cont> __first,
951  ::__gnu_cxx::__normal_iterator<_Ite, _Cont> __last,
952  const _Tp& __value)
953  { std::__fill_a1(__first.base(), __last.base(), __value); }
954 
955  template<typename _Tp, typename _VTp>
956  void
957  __fill_a1(const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
958  const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
959  const _VTp&);
960 
961  _GLIBCXX20_CONSTEXPR
962  void
963  __fill_a1(_GLIBCXX_STD_C::_Bit_iterator, _GLIBCXX_STD_C::_Bit_iterator,
964  const bool&);
965 
966  template<typename _FIte, typename _Tp>
967  _GLIBCXX20_CONSTEXPR
968  inline void
969  __fill_a(_FIte __first, _FIte __last, const _Tp& __value)
970  { std::__fill_a1(__first, __last, __value); }
971 
972  template<typename _Ite, typename _Seq, typename _Cat, typename _Tp>
973  void
974  __fill_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
975  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
976  const _Tp&);
977 
978  /**
979  * @brief Fills the range [first,last) with copies of value.
980  * @ingroup mutating_algorithms
981  * @param __first A forward iterator.
982  * @param __last A forward iterator.
983  * @param __value A reference-to-const of arbitrary type.
984  * @return Nothing.
985  *
986  * This function fills a range with copies of the same value. For char
987  * types filling contiguous areas of memory, this becomes an inline call
988  * to @c memset or @c wmemset.
989  */
990  template<typename _ForwardIterator, typename _Tp>
991  _GLIBCXX20_CONSTEXPR
992  inline void
993  fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
994  {
995  // concept requirements
996  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
997  _ForwardIterator>)
998  __glibcxx_requires_valid_range(__first, __last);
999 
1000  std::__fill_a(__first, __last, __value);
1001  }
1002 
1003  // Used by fill_n, generate_n, etc. to convert _Size to an integral type:
1004  inline _GLIBCXX_CONSTEXPR int
1005  __size_to_integer(int __n) { return __n; }
1006  inline _GLIBCXX_CONSTEXPR unsigned
1007  __size_to_integer(unsigned __n) { return __n; }
1008  inline _GLIBCXX_CONSTEXPR long
1009  __size_to_integer(long __n) { return __n; }
1010  inline _GLIBCXX_CONSTEXPR unsigned long
1011  __size_to_integer(unsigned long __n) { return __n; }
1012  inline _GLIBCXX_CONSTEXPR long long
1013  __size_to_integer(long long __n) { return __n; }
1014  inline _GLIBCXX_CONSTEXPR unsigned long long
1015  __size_to_integer(unsigned long long __n) { return __n; }
1016 
1017 #if defined(__GLIBCXX_TYPE_INT_N_0)
1018  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_0
1019  __size_to_integer(__GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1020  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_0
1021  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1022 #endif
1023 #if defined(__GLIBCXX_TYPE_INT_N_1)
1024  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_1
1025  __size_to_integer(__GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1026  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_1
1027  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1028 #endif
1029 #if defined(__GLIBCXX_TYPE_INT_N_2)
1030  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_2
1031  __size_to_integer(__GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1032  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_2
1033  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1034 #endif
1035 #if defined(__GLIBCXX_TYPE_INT_N_3)
1036  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_3
1037  __size_to_integer(__GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1038  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_3
1039  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1040 #endif
1041 
1042  inline _GLIBCXX_CONSTEXPR long long
1043  __size_to_integer(float __n) { return (long long)__n; }
1044  inline _GLIBCXX_CONSTEXPR long long
1045  __size_to_integer(double __n) { return (long long)__n; }
1046  inline _GLIBCXX_CONSTEXPR long long
1047  __size_to_integer(long double __n) { return (long long)__n; }
1048 #if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128) && !defined(__CUDACC__)
1049  __extension__ inline _GLIBCXX_CONSTEXPR long long
1050  __size_to_integer(__float128 __n) { return (long long)__n; }
1051 #endif
1052 
1053  template<typename _OutputIterator, typename _Size, typename _Tp>
1054  _GLIBCXX20_CONSTEXPR
1055  inline typename
1056  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
1057  __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
1058  {
1059  for (; __n > 0; --__n, (void) ++__first)
1060  *__first = __value;
1061  return __first;
1062  }
1063 
1064  template<typename _OutputIterator, typename _Size, typename _Tp>
1065  _GLIBCXX20_CONSTEXPR
1066  inline typename
1067  __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
1068  __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
1069  {
1070  const _Tp __tmp = __value;
1071  for (; __n > 0; --__n, (void) ++__first)
1072  *__first = __tmp;
1073  return __first;
1074  }
1075 
1076  template<typename _Ite, typename _Seq, typename _Cat, typename _Size,
1077  typename _Tp>
1078  ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
1079  __fill_n_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>& __first,
1080  _Size __n, const _Tp& __value,
1081  std::input_iterator_tag);
1082 
1083  template<typename _OutputIterator, typename _Size, typename _Tp>
1084  _GLIBCXX20_CONSTEXPR
1085  inline _OutputIterator
1086  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1087  std::output_iterator_tag)
1088  {
1089 #if __cplusplus >= 201103L
1090  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1091 #endif
1092  return __fill_n_a1(__first, __n, __value);
1093  }
1094 
1095  template<typename _OutputIterator, typename _Size, typename _Tp>
1096  _GLIBCXX20_CONSTEXPR
1097  inline _OutputIterator
1098  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1099  std::input_iterator_tag)
1100  {
1101 #if __cplusplus >= 201103L
1102  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1103 #endif
1104  return __fill_n_a1(__first, __n, __value);
1105  }
1106 
1107  template<typename _OutputIterator, typename _Size, typename _Tp>
1108  _GLIBCXX20_CONSTEXPR
1109  inline _OutputIterator
1110  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1111  std::random_access_iterator_tag)
1112  {
1113 #if __cplusplus >= 201103L
1114  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1115 #endif
1116  if (__n <= 0)
1117  return __first;
1118 
1119  __glibcxx_requires_can_increment(__first, __n);
1120 
1121  std::__fill_a(__first, __first + __n, __value);
1122  return __first + __n;
1123  }
1124 
1125  /**
1126  * @brief Fills the range [first,first+n) with copies of value.
1127  * @ingroup mutating_algorithms
1128  * @param __first An output iterator.
1129  * @param __n The count of copies to perform.
1130  * @param __value A reference-to-const of arbitrary type.
1131  * @return The iterator at first+n.
1132  *
1133  * This function fills a range with copies of the same value. For char
1134  * types filling contiguous areas of memory, this becomes an inline call
1135  * to @c memset or @c wmemset.
1136  *
1137  * If @p __n is negative, the function does nothing.
1138  */
1139  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1140  // DR 865. More algorithms that throw away information
1141  // DR 426. search_n(), fill_n(), and generate_n() with negative n
1142  template<typename _OI, typename _Size, typename _Tp>
1143  _GLIBCXX20_CONSTEXPR
1144  inline _OI
1145  fill_n(_OI __first, _Size __n, const _Tp& __value)
1146  {
1147  // concept requirements
1148  __glibcxx_function_requires(_OutputIteratorConcept<_OI, const _Tp&>)
1149 
1150  return std::__fill_n_a(__first, std::__size_to_integer(__n), __value,
1151  std::__iterator_category(__first));
1152  }
1153 
1154  template<bool _BoolType>
1155  struct __equal
1156  {
1157  template<typename _II1, typename _II2>
1158  _GLIBCXX20_CONSTEXPR
1159  static bool
1160  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1161  {
1162  for (; __first1 != __last1; ++__first1, (void) ++__first2)
1163  if (!(*__first1 == *__first2))
1164  return false;
1165  return true;
1166  }
1167  };
1168 
1169  template<>
1170  struct __equal<true>
1171  {
1172  template<typename _Tp>
1173  _GLIBCXX20_CONSTEXPR
1174  static bool
1175  equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
1176  {
1177  if (const size_t __len = (__last1 - __first1))
1178  return !std::__memcmp(__first1, __first2, __len);
1179  return true;
1180  }
1181  };
1182 
1183  template<typename _Tp, typename _Ref, typename _Ptr, typename _II>
1184  typename __gnu_cxx::__enable_if<
1185  __is_random_access_iter<_II>::__value, bool>::__type
1186  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1187  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1188  _II);
1189 
1190  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1191  typename _Tp2, typename _Ref2, typename _Ptr2>
1192  bool
1193  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1194  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1195  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1196 
1197  template<typename _II, typename _Tp, typename _Ref, typename _Ptr>
1198  typename __gnu_cxx::__enable_if<
1199  __is_random_access_iter<_II>::__value, bool>::__type
1200  __equal_aux1(_II, _II,
1201  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>);
1202 
1203  template<typename _II1, typename _II2>
1204  _GLIBCXX20_CONSTEXPR
1205  inline bool
1206  __equal_aux1(_II1 __first1, _II1 __last1, _II2 __first2)
1207  {
1208  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1209  const bool __simple = ((__is_integer<_ValueType1>::__value
1210  || __is_pointer<_ValueType1>::__value)
1211  && __memcmpable<_II1, _II2>::__value);
1212  return std::__equal<__simple>::equal(__first1, __last1, __first2);
1213  }
1214 
1215  template<typename _II1, typename _II2>
1216  _GLIBCXX20_CONSTEXPR
1217  inline bool
1218  __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
1219  {
1220  return std::__equal_aux1(std::__niter_base(__first1),
1221  std::__niter_base(__last1),
1222  std::__niter_base(__first2));
1223  }
1224 
1225  template<typename _II1, typename _Seq1, typename _Cat1, typename _II2>
1226  bool
1227  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1228  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1229  _II2);
1230 
1231  template<typename _II1, typename _II2, typename _Seq2, typename _Cat2>
1232  bool
1233  __equal_aux(_II1, _II1,
1234  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1235 
1236  template<typename _II1, typename _Seq1, typename _Cat1,
1237  typename _II2, typename _Seq2, typename _Cat2>
1238  bool
1239  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1240  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1241  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1242 
1243  template<typename, typename>
1244  struct __lc_rai
1245  {
1246  template<typename _II1, typename _II2>
1247  _GLIBCXX20_CONSTEXPR
1248  static _II1
1249  __newlast1(_II1, _II1 __last1, _II2, _II2)
1250  { return __last1; }
1251 
1252  template<typename _II>
1253  _GLIBCXX20_CONSTEXPR
1254  static bool
1255  __cnd2(_II __first, _II __last)
1256  { return __first != __last; }
1257  };
1258 
1259  template<>
1260  struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
1261  {
1262  template<typename _RAI1, typename _RAI2>
1263  _GLIBCXX20_CONSTEXPR
1264  static _RAI1
1265  __newlast1(_RAI1 __first1, _RAI1 __last1,
1266  _RAI2 __first2, _RAI2 __last2)
1267  {
1268  const typename iterator_traits<_RAI1>::difference_type
1269  __diff1 = __last1 - __first1;
1270  const typename iterator_traits<_RAI2>::difference_type
1271  __diff2 = __last2 - __first2;
1272  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
1273  }
1274 
1275  template<typename _RAI>
1276  static _GLIBCXX20_CONSTEXPR bool
1277  __cnd2(_RAI, _RAI)
1278  { return true; }
1279  };
1280 
1281  template<typename _II1, typename _II2, typename _Compare>
1282  _GLIBCXX20_CONSTEXPR
1283  bool
1284  __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
1285  _II2 __first2, _II2 __last2,
1286  _Compare __comp)
1287  {
1288  typedef typename iterator_traits<_II1>::iterator_category _Category1;
1289  typedef typename iterator_traits<_II2>::iterator_category _Category2;
1290  typedef std::__lc_rai<_Category1, _Category2> __rai_type;
1291 
1292  __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1293  for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1294  ++__first1, (void)++__first2)
1295  {
1296  if (__comp(__first1, __first2))
1297  return true;
1298  if (__comp(__first2, __first1))
1299  return false;
1300  }
1301  return __first1 == __last1 && __first2 != __last2;
1302  }
1303 
1304  template<bool _BoolType>
1305  struct __lexicographical_compare
1306  {
1307  template<typename _II1, typename _II2>
1308  _GLIBCXX20_CONSTEXPR
1309  static bool
1310  __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1311  {
1312  using __gnu_cxx::__ops::__iter_less_iter;
1313  return std::__lexicographical_compare_impl(__first1, __last1,
1314  __first2, __last2,
1315  __iter_less_iter());
1316  }
1317 
1318  template<typename _II1, typename _II2>
1319  _GLIBCXX20_CONSTEXPR
1320  static int
1321  __3way(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1322  {
1323  while (__first1 != __last1)
1324  {
1325  if (__first2 == __last2)
1326  return +1;
1327  if (*__first1 < *__first2)
1328  return -1;
1329  if (*__first2 < *__first1)
1330  return +1;
1331  ++__first1;
1332  ++__first2;
1333  }
1334  return int(__first2 == __last2) - 1;
1335  }
1336  };
1337 
1338  template<>
1339  struct __lexicographical_compare<true>
1340  {
1341  template<typename _Tp, typename _Up>
1342  _GLIBCXX20_CONSTEXPR
1343  static bool
1344  __lc(const _Tp* __first1, const _Tp* __last1,
1345  const _Up* __first2, const _Up* __last2)
1346  { return __3way(__first1, __last1, __first2, __last2) < 0; }
1347 
1348  template<typename _Tp, typename _Up>
1349  _GLIBCXX20_CONSTEXPR
1350  static ptrdiff_t
1351  __3way(const _Tp* __first1, const _Tp* __last1,
1352  const _Up* __first2, const _Up* __last2)
1353  {
1354  const size_t __len1 = __last1 - __first1;
1355  const size_t __len2 = __last2 - __first2;
1356  if (const size_t __len = std::min(__len1, __len2))
1357  if (int __result = std::__memcmp(__first1, __first2, __len))
1358  return __result;
1359  return ptrdiff_t(__len1 - __len2);
1360  }
1361  };
1362 
1363  template<typename _II1, typename _II2>
1364  _GLIBCXX20_CONSTEXPR
1365  inline bool
1366  __lexicographical_compare_aux1(_II1 __first1, _II1 __last1,
1367  _II2 __first2, _II2 __last2)
1368  {
1369  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1370  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1371  const bool __simple =
1372  (__is_memcmp_ordered_with<_ValueType1, _ValueType2>::__value
1373  && __is_pointer<_II1>::__value
1374  && __is_pointer<_II2>::__value
1375 #if __cplusplus > 201703L && __cpp_lib_concepts
1376  // For C++20 iterator_traits<volatile T*>::value_type is non-volatile
1377  // so __is_byte<T> could be true, but we can't use memcmp with
1378  // volatile data.
1379  && !is_volatile_v<remove_reference_t<iter_reference_t<_II1>>>
1380  && !is_volatile_v<remove_reference_t<iter_reference_t<_II2>>>
1381 #endif
1382  );
1383 
1384  return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
1385  __first2, __last2);
1386  }
1387 
1388  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1389  typename _Tp2>
1390  bool
1391  __lexicographical_compare_aux1(
1392  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1393  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1394  _Tp2*, _Tp2*);
1395 
1396  template<typename _Tp1,
1397  typename _Tp2, typename _Ref2, typename _Ptr2>
1398  bool
1399  __lexicographical_compare_aux1(_Tp1*, _Tp1*,
1400  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1401  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1402 
1403  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1404  typename _Tp2, typename _Ref2, typename _Ptr2>
1405  bool
1406  __lexicographical_compare_aux1(
1407  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1408  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1409  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1410  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1411 
1412  template<typename _II1, typename _II2>
1413  _GLIBCXX20_CONSTEXPR
1414  inline bool
1415  __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
1416  _II2 __first2, _II2 __last2)
1417  {
1418  return std::__lexicographical_compare_aux1(std::__niter_base(__first1),
1419  std::__niter_base(__last1),
1420  std::__niter_base(__first2),
1421  std::__niter_base(__last2));
1422  }
1423 
1424  template<typename _Iter1, typename _Seq1, typename _Cat1,
1425  typename _II2>
1426  bool
1427  __lexicographical_compare_aux(
1428  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1429  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1430  _II2, _II2);
1431 
1432  template<typename _II1,
1433  typename _Iter2, typename _Seq2, typename _Cat2>
1434  bool
1435  __lexicographical_compare_aux(
1436  _II1, _II1,
1437  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1438  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1439 
1440  template<typename _Iter1, typename _Seq1, typename _Cat1,
1441  typename _Iter2, typename _Seq2, typename _Cat2>
1442  bool
1443  __lexicographical_compare_aux(
1444  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1445  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1446  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1447  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1448 
1449  template<typename _ForwardIterator, typename _Tp, typename _Compare>
1450  _GLIBCXX20_CONSTEXPR
1451  _ForwardIterator
1452  __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1453  const _Tp& __val, _Compare __comp)
1454  {
1455  typedef typename iterator_traits<_ForwardIterator>::difference_type
1456  _DistanceType;
1457 
1458  _DistanceType __len = std::distance(__first, __last);
1459 
1460  while (__len > 0)
1461  {
1462  _DistanceType __half = __len >> 1;
1463  _ForwardIterator __middle = __first;
1464  std::advance(__middle, __half);
1465  if (__comp(__middle, __val))
1466  {
1467  __first = __middle;
1468  ++__first;
1469  __len = __len - __half - 1;
1470  }
1471  else
1472  __len = __half;
1473  }
1474  return __first;
1475  }
1476 
1477  /**
1478  * @brief Finds the first position in which @a val could be inserted
1479  * without changing the ordering.
1480  * @param __first An iterator.
1481  * @param __last Another iterator.
1482  * @param __val The search term.
1483  * @return An iterator pointing to the first element <em>not less
1484  * than</em> @a val, or end() if every element is less than
1485  * @a val.
1486  * @ingroup binary_search_algorithms
1487  */
1488  template<typename _ForwardIterator, typename _Tp>
1489  _GLIBCXX20_CONSTEXPR
1490  inline _ForwardIterator
1491  lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1492  const _Tp& __val)
1493  {
1494  // concept requirements
1495  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
1496  __glibcxx_function_requires(_LessThanOpConcept<
1497  typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
1498  __glibcxx_requires_partitioned_lower(__first, __last, __val);
1499 
1500  return std::__lower_bound(__first, __last, __val,
1501  __gnu_cxx::__ops::__iter_less_val());
1502  }
1503 
1504  /// This is a helper function for the sort routines and for random.tcc.
1505  // Precondition: __n > 0.
1506  inline _GLIBCXX_CONSTEXPR int
1507  __lg(int __n)
1508  { return (int)sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
1509 
1510  inline _GLIBCXX_CONSTEXPR unsigned
1511  __lg(unsigned __n)
1512  { return (int)sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
1513 
1514  inline _GLIBCXX_CONSTEXPR long
1515  __lg(long __n)
1516  { return (int)sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1517 
1518  inline _GLIBCXX_CONSTEXPR unsigned long
1519  __lg(unsigned long __n)
1520  { return (int)sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1521 
1522  inline _GLIBCXX_CONSTEXPR long long
1523  __lg(long long __n)
1524  { return (int)sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1525 
1526  inline _GLIBCXX_CONSTEXPR unsigned long long
1527  __lg(unsigned long long __n)
1528  { return (int)sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1529 
1530 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1531 
1532  /**
1533  * @brief Tests a range for element-wise equality.
1534  * @ingroup non_mutating_algorithms
1535  * @param __first1 An input iterator.
1536  * @param __last1 An input iterator.
1537  * @param __first2 An input iterator.
1538  * @return A boolean true or false.
1539  *
1540  * This compares the elements of two ranges using @c == and returns true or
1541  * false depending on whether all of the corresponding elements of the
1542  * ranges are equal.
1543  */
1544  template<typename _II1, typename _II2>
1545  _GLIBCXX20_CONSTEXPR
1546  inline bool
1547  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1548  {
1549  // concept requirements
1550  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1551  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1552  __glibcxx_function_requires(_EqualOpConcept<
1553  typename iterator_traits<_II1>::value_type,
1554  typename iterator_traits<_II2>::value_type>)
1555  __glibcxx_requires_can_increment_range(__first1, __last1, __first2);
1556 
1557  return std::__equal_aux(__first1, __last1, __first2);
1558  }
1559 
1560  /**
1561  * @brief Tests a range for element-wise equality.
1562  * @ingroup non_mutating_algorithms
1563  * @param __first1 An input iterator.
1564  * @param __last1 An input iterator.
1565  * @param __first2 An input iterator.
1566  * @param __binary_pred A binary predicate @link functors
1567  * functor@endlink.
1568  * @return A boolean true or false.
1569  *
1570  * This compares the elements of two ranges using the binary_pred
1571  * parameter, and returns true or
1572  * false depending on whether all of the corresponding elements of the
1573  * ranges are equal.
1574  */
1575  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1576  _GLIBCXX20_CONSTEXPR
1577  inline bool
1578  equal(_IIter1 __first1, _IIter1 __last1,
1579  _IIter2 __first2, _BinaryPredicate __binary_pred)
1580  {
1581  // concept requirements
1582  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1583  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1584  __glibcxx_requires_valid_range(__first1, __last1);
1585 
1586  for (; __first1 != __last1; ++__first1, (void)++__first2)
1587  if (!bool(__binary_pred(*__first1, *__first2)))
1588  return false;
1589  return true;
1590  }
1591 
1592 #if __cplusplus >= 201103L
1593  // 4-iterator version of std::equal<It1, It2> for use in C++11.
1594  template<typename _II1, typename _II2>
1595  _GLIBCXX20_CONSTEXPR
1596  inline bool
1597  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1598  {
1599  using _RATag = random_access_iterator_tag;
1600  using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1601  using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1602  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1603  if (_RAIters())
1604  {
1605  auto __d1 = std::distance(__first1, __last1);
1606  auto __d2 = std::distance(__first2, __last2);
1607  if (__d1 != __d2)
1608  return false;
1609  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1610  }
1611 
1612  for (; __first1 != __last1 && __first2 != __last2;
1613  ++__first1, (void)++__first2)
1614  if (!(*__first1 == *__first2))
1615  return false;
1616  return __first1 == __last1 && __first2 == __last2;
1617  }
1618 
1619  // 4-iterator version of std::equal<It1, It2, BinaryPred> for use in C++11.
1620  template<typename _II1, typename _II2, typename _BinaryPredicate>
1621  _GLIBCXX20_CONSTEXPR
1622  inline bool
1623  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2,
1624  _BinaryPredicate __binary_pred)
1625  {
1626  using _RATag = random_access_iterator_tag;
1627  using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1628  using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1629  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1630  if (_RAIters())
1631  {
1632  auto __d1 = std::distance(__first1, __last1);
1633  auto __d2 = std::distance(__first2, __last2);
1634  if (__d1 != __d2)
1635  return false;
1636  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1637  __binary_pred);
1638  }
1639 
1640  for (; __first1 != __last1 && __first2 != __last2;
1641  ++__first1, (void)++__first2)
1642  if (!bool(__binary_pred(*__first1, *__first2)))
1643  return false;
1644  return __first1 == __last1 && __first2 == __last2;
1645  }
1646 #endif // C++11
1647 
1648 #if __cplusplus > 201103L
1649 
1650 #define __cpp_lib_robust_nonmodifying_seq_ops 201304L
1651 
1652  /**
1653  * @brief Tests a range for element-wise equality.
1654  * @ingroup non_mutating_algorithms
1655  * @param __first1 An input iterator.
1656  * @param __last1 An input iterator.
1657  * @param __first2 An input iterator.
1658  * @param __last2 An input iterator.
1659  * @return A boolean true or false.
1660  *
1661  * This compares the elements of two ranges using @c == and returns true or
1662  * false depending on whether all of the corresponding elements of the
1663  * ranges are equal.
1664  */
1665  template<typename _II1, typename _II2>
1666  _GLIBCXX20_CONSTEXPR
1667  inline bool
1668  equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1669  {
1670  // concept requirements
1671  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1672  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1673  __glibcxx_function_requires(_EqualOpConcept<
1674  typename iterator_traits<_II1>::value_type,
1675  typename iterator_traits<_II2>::value_type>)
1676  __glibcxx_requires_valid_range(__first1, __last1);
1677  __glibcxx_requires_valid_range(__first2, __last2);
1678 
1679  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2);
1680  }
1681 
1682  /**
1683  * @brief Tests a range for element-wise equality.
1684  * @ingroup non_mutating_algorithms
1685  * @param __first1 An input iterator.
1686  * @param __last1 An input iterator.
1687  * @param __first2 An input iterator.
1688  * @param __last2 An input iterator.
1689  * @param __binary_pred A binary predicate @link functors
1690  * functor@endlink.
1691  * @return A boolean true or false.
1692  *
1693  * This compares the elements of two ranges using the binary_pred
1694  * parameter, and returns true or
1695  * false depending on whether all of the corresponding elements of the
1696  * ranges are equal.
1697  */
1698  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1699  _GLIBCXX20_CONSTEXPR
1700  inline bool
1701  equal(_IIter1 __first1, _IIter1 __last1,
1702  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1703  {
1704  // concept requirements
1705  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1706  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1707  __glibcxx_requires_valid_range(__first1, __last1);
1708  __glibcxx_requires_valid_range(__first2, __last2);
1709 
1710  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2,
1711  __binary_pred);
1712  }
1713 #endif // C++14
1714 
1715  /**
1716  * @brief Performs @b dictionary comparison on ranges.
1717  * @ingroup sorting_algorithms
1718  * @param __first1 An input iterator.
1719  * @param __last1 An input iterator.
1720  * @param __first2 An input iterator.
1721  * @param __last2 An input iterator.
1722  * @return A boolean true or false.
1723  *
1724  * <em>Returns true if the sequence of elements defined by the range
1725  * [first1,last1) is lexicographically less than the sequence of elements
1726  * defined by the range [first2,last2). Returns false otherwise.</em>
1727  * (Quoted from [25.3.8]/1.) If the iterators are all character pointers,
1728  * then this is an inline call to @c memcmp.
1729  */
1730  template<typename _II1, typename _II2>
1731  _GLIBCXX20_CONSTEXPR
1732  inline bool
1733  lexicographical_compare(_II1 __first1, _II1 __last1,
1734  _II2 __first2, _II2 __last2)
1735  {
1736 #ifdef _GLIBCXX_CONCEPT_CHECKS
1737  // concept requirements
1738  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1739  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1740 #endif
1741  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1742  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1743  __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1744  __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1745  __glibcxx_requires_valid_range(__first1, __last1);
1746  __glibcxx_requires_valid_range(__first2, __last2);
1747 
1748  return std::__lexicographical_compare_aux(__first1, __last1,
1749  __first2, __last2);
1750  }
1751 
1752  /**
1753  * @brief Performs @b dictionary comparison on ranges.
1754  * @ingroup sorting_algorithms
1755  * @param __first1 An input iterator.
1756  * @param __last1 An input iterator.
1757  * @param __first2 An input iterator.
1758  * @param __last2 An input iterator.
1759  * @param __comp A @link comparison_functors comparison functor@endlink.
1760  * @return A boolean true or false.
1761  *
1762  * The same as the four-parameter @c lexicographical_compare, but uses the
1763  * comp parameter instead of @c <.
1764  */
1765  template<typename _II1, typename _II2, typename _Compare>
1766  _GLIBCXX20_CONSTEXPR
1767  inline bool
1768  lexicographical_compare(_II1 __first1, _II1 __last1,
1769  _II2 __first2, _II2 __last2, _Compare __comp)
1770  {
1771  // concept requirements
1772  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1773  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1774  __glibcxx_requires_valid_range(__first1, __last1);
1775  __glibcxx_requires_valid_range(__first2, __last2);
1776 
1777  return std::__lexicographical_compare_impl
1778  (__first1, __last1, __first2, __last2,
1779  __gnu_cxx::__ops::__iter_comp_iter(__comp));
1780  }
1781 
1782 #if __cpp_lib_three_way_comparison
1783  // Both iterators refer to contiguous ranges of unsigned narrow characters,
1784  // or std::byte, or big-endian unsigned integers, suitable for comparison
1785  // using memcmp.
1786  template<typename _Iter1, typename _Iter2>
1787  concept __memcmp_ordered_with
1788  = (__is_memcmp_ordered_with<iter_value_t<_Iter1>,
1789  iter_value_t<_Iter2>>::__value)
1790  && contiguous_iterator<_Iter1> && contiguous_iterator<_Iter2>;
1791 
1792  // Return a struct with two members, initialized to the smaller of x and y
1793  // (or x if they compare equal) and the result of the comparison x <=> y.
1794  template<typename _Tp>
1795  constexpr auto
1796  __min_cmp(_Tp __x, _Tp __y)
1797  {
1798  struct _Res {
1799  _Tp _M_min;
1800  decltype(__x <=> __y) _M_cmp;
1801  };
1802  auto __c = __x <=> __y;
1803  if (__c > 0)
1804  return _Res{__y, __c};
1805  return _Res{__x, __c};
1806  }
1807 
1808  /**
1809  * @brief Performs dictionary comparison on ranges.
1810  * @ingroup sorting_algorithms
1811  * @param __first1 An input iterator.
1812  * @param __last1 An input iterator.
1813  * @param __first2 An input iterator.
1814  * @param __last2 An input iterator.
1815  * @param __comp A @link comparison_functors comparison functor@endlink.
1816  * @return The comparison category that `__comp(*__first1, *__first2)`
1817  * returns.
1818  */
1819  template<typename _InputIter1, typename _InputIter2, typename _Comp>
1820  constexpr auto
1821  lexicographical_compare_three_way(_InputIter1 __first1,
1822  _InputIter1 __last1,
1823  _InputIter2 __first2,
1824  _InputIter2 __last2,
1825  _Comp __comp)
1826  -> decltype(__comp(*__first1, *__first2))
1827  {
1828  // concept requirements
1829  __glibcxx_function_requires(_InputIteratorConcept<_InputIter1>)
1830  __glibcxx_function_requires(_InputIteratorConcept<_InputIter2>)
1831  __glibcxx_requires_valid_range(__first1, __last1);
1832  __glibcxx_requires_valid_range(__first2, __last2);
1833 
1834  using _Cat = decltype(__comp(*__first1, *__first2));
1835  static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
1836 
1837  if (!std::__is_constant_evaluated())
1838  if constexpr (same_as<_Comp, __detail::_Synth3way>
1839  || same_as<_Comp, compare_three_way>)
1840  if constexpr (__memcmp_ordered_with<_InputIter1, _InputIter2>)
1841  {
1842  const auto [__len, __lencmp] = _GLIBCXX_STD_A::
1843  __min_cmp(__last1 - __first1, __last2 - __first2);
1844  if (__len)
1845  {
1846  const auto __blen = __len * sizeof(*__first1);
1847  const auto __c
1848  = __builtin_memcmp(&*__first1, &*__first2, __blen) <=> 0;
1849  if (__c != 0)
1850  return __c;
1851  }
1852  return __lencmp;
1853  }
1854 
1855  while (__first1 != __last1)
1856  {
1857  if (__first2 == __last2)
1858  return strong_ordering::greater;
1859  if (auto __cmp = __comp(*__first1, *__first2); __cmp != 0)
1860  return __cmp;
1861  ++__first1;
1862  ++__first2;
1863  }
1864  return (__first2 == __last2) <=> true; // See PR 94006
1865  }
1866 
1867  template<typename _InputIter1, typename _InputIter2>
1868  constexpr auto
1869  lexicographical_compare_three_way(_InputIter1 __first1,
1870  _InputIter1 __last1,
1871  _InputIter2 __first2,
1872  _InputIter2 __last2)
1873  {
1874  return _GLIBCXX_STD_A::
1875  lexicographical_compare_three_way(__first1, __last1, __first2, __last2,
1876  compare_three_way{});
1877  }
1878 #endif // three_way_comparison
1879 
1880  template<typename _InputIterator1, typename _InputIterator2,
1881  typename _BinaryPredicate>
1882  _GLIBCXX20_CONSTEXPR
1883  pair<_InputIterator1, _InputIterator2>
1884  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1885  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1886  {
1887  while (__first1 != __last1 && __binary_pred(__first1, __first2))
1888  {
1889  ++__first1;
1890  ++__first2;
1891  }
1892  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1893  }
1894 
1895  /**
1896  * @brief Finds the places in ranges which don't match.
1897  * @ingroup non_mutating_algorithms
1898  * @param __first1 An input iterator.
1899  * @param __last1 An input iterator.
1900  * @param __first2 An input iterator.
1901  * @return A pair of iterators pointing to the first mismatch.
1902  *
1903  * This compares the elements of two ranges using @c == and returns a pair
1904  * of iterators. The first iterator points into the first range, the
1905  * second iterator points into the second range, and the elements pointed
1906  * to by the iterators are not equal.
1907  */
1908  template<typename _InputIterator1, typename _InputIterator2>
1909  _GLIBCXX20_CONSTEXPR
1910  inline pair<_InputIterator1, _InputIterator2>
1911  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1912  _InputIterator2 __first2)
1913  {
1914  // concept requirements
1915  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1916  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1917  __glibcxx_function_requires(_EqualOpConcept<
1918  typename iterator_traits<_InputIterator1>::value_type,
1919  typename iterator_traits<_InputIterator2>::value_type>)
1920  __glibcxx_requires_valid_range(__first1, __last1);
1921 
1922  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1923  __gnu_cxx::__ops::__iter_equal_to_iter());
1924  }
1925 
1926  /**
1927  * @brief Finds the places in ranges which don't match.
1928  * @ingroup non_mutating_algorithms
1929  * @param __first1 An input iterator.
1930  * @param __last1 An input iterator.
1931  * @param __first2 An input iterator.
1932  * @param __binary_pred A binary predicate @link functors
1933  * functor@endlink.
1934  * @return A pair of iterators pointing to the first mismatch.
1935  *
1936  * This compares the elements of two ranges using the binary_pred
1937  * parameter, and returns a pair
1938  * of iterators. The first iterator points into the first range, the
1939  * second iterator points into the second range, and the elements pointed
1940  * to by the iterators are not equal.
1941  */
1942  template<typename _InputIterator1, typename _InputIterator2,
1943  typename _BinaryPredicate>
1944  _GLIBCXX20_CONSTEXPR
1945  inline pair<_InputIterator1, _InputIterator2>
1946  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1947  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1948  {
1949  // concept requirements
1950  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1951  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1952  __glibcxx_requires_valid_range(__first1, __last1);
1953 
1954  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1955  __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1956  }
1957 
1958 #if __cplusplus > 201103L
1959 
1960  template<typename _InputIterator1, typename _InputIterator2,
1961  typename _BinaryPredicate>
1962  _GLIBCXX20_CONSTEXPR
1963  pair<_InputIterator1, _InputIterator2>
1964  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1965  _InputIterator2 __first2, _InputIterator2 __last2,
1966  _BinaryPredicate __binary_pred)
1967  {
1968  while (__first1 != __last1 && __first2 != __last2
1969  && __binary_pred(__first1, __first2))
1970  {
1971  ++__first1;
1972  ++__first2;
1973  }
1974  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1975  }
1976 
1977  /**
1978  * @brief Finds the places in ranges which don't match.
1979  * @ingroup non_mutating_algorithms
1980  * @param __first1 An input iterator.
1981  * @param __last1 An input iterator.
1982  * @param __first2 An input iterator.
1983  * @param __last2 An input iterator.
1984  * @return A pair of iterators pointing to the first mismatch.
1985  *
1986  * This compares the elements of two ranges using @c == and returns a pair
1987  * of iterators. The first iterator points into the first range, the
1988  * second iterator points into the second range, and the elements pointed
1989  * to by the iterators are not equal.
1990  */
1991  template<typename _InputIterator1, typename _InputIterator2>
1992  _GLIBCXX20_CONSTEXPR
1993  inline pair<_InputIterator1, _InputIterator2>
1994  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1995  _InputIterator2 __first2, _InputIterator2 __last2)
1996  {
1997  // concept requirements
1998  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1999  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2000  __glibcxx_function_requires(_EqualOpConcept<
2001  typename iterator_traits<_InputIterator1>::value_type,
2002  typename iterator_traits<_InputIterator2>::value_type>)
2003  __glibcxx_requires_valid_range(__first1, __last1);
2004  __glibcxx_requires_valid_range(__first2, __last2);
2005 
2006  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2007  __gnu_cxx::__ops::__iter_equal_to_iter());
2008  }
2009 
2010  /**
2011  * @brief Finds the places in ranges which don't match.
2012  * @ingroup non_mutating_algorithms
2013  * @param __first1 An input iterator.
2014  * @param __last1 An input iterator.
2015  * @param __first2 An input iterator.
2016  * @param __last2 An input iterator.
2017  * @param __binary_pred A binary predicate @link functors
2018  * functor@endlink.
2019  * @return A pair of iterators pointing to the first mismatch.
2020  *
2021  * This compares the elements of two ranges using the binary_pred
2022  * parameter, and returns a pair
2023  * of iterators. The first iterator points into the first range, the
2024  * second iterator points into the second range, and the elements pointed
2025  * to by the iterators are not equal.
2026  */
2027  template<typename _InputIterator1, typename _InputIterator2,
2028  typename _BinaryPredicate>
2029  _GLIBCXX20_CONSTEXPR
2030  inline pair<_InputIterator1, _InputIterator2>
2031  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
2032  _InputIterator2 __first2, _InputIterator2 __last2,
2033  _BinaryPredicate __binary_pred)
2034  {
2035  // concept requirements
2036  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2037  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2038  __glibcxx_requires_valid_range(__first1, __last1);
2039  __glibcxx_requires_valid_range(__first2, __last2);
2040 
2041  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2042  __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
2043  }
2044 #endif
2045 
2046 _GLIBCXX_END_NAMESPACE_ALGO
2047 
2048  /// This is an overload used by find algos for the Input Iterator case.
2049  template<typename _InputIterator, typename _Predicate>
2050  _GLIBCXX20_CONSTEXPR
2051  inline _InputIterator
2052  __find_if(_InputIterator __first, _InputIterator __last,
2053  _Predicate __pred, input_iterator_tag)
2054  {
2055  while (__first != __last && !__pred(__first))
2056  ++__first;
2057  return __first;
2058  }
2059 
2060  /// This is an overload used by find algos for the RAI case.
2061  template<typename _RandomAccessIterator, typename _Predicate>
2062  _GLIBCXX20_CONSTEXPR
2063  _RandomAccessIterator
2064  __find_if(_RandomAccessIterator __first, _RandomAccessIterator __last,
2065  _Predicate __pred, random_access_iterator_tag)
2066  {
2067  typename iterator_traits<_RandomAccessIterator>::difference_type
2068  __trip_count = (__last - __first) >> 2;
2069 
2070  for (; __trip_count > 0; --__trip_count)
2071  {
2072  if (__pred(__first))
2073  return __first;
2074  ++__first;
2075 
2076  if (__pred(__first))
2077  return __first;
2078  ++__first;
2079 
2080  if (__pred(__first))
2081  return __first;
2082  ++__first;
2083 
2084  if (__pred(__first))
2085  return __first;
2086  ++__first;
2087  }
2088 
2089  switch (__last - __first)
2090  {
2091  case 3:
2092  if (__pred(__first))
2093  return __first;
2094  ++__first;
2095  // FALLTHRU
2096  case 2:
2097  if (__pred(__first))
2098  return __first;
2099  ++__first;
2100  // FALLTHRU
2101  case 1:
2102  if (__pred(__first))
2103  return __first;
2104  ++__first;
2105  // FALLTHRU
2106  case 0:
2107  default:
2108  return __last;
2109  }
2110  }
2111 
2112  template<typename _Iterator, typename _Predicate>
2113  _GLIBCXX20_CONSTEXPR
2114  inline _Iterator
2115  __find_if(_Iterator __first, _Iterator __last, _Predicate __pred)
2116  {
2117  return __find_if(__first, __last, __pred,
2118  std::__iterator_category(__first));
2119  }
2120 
2121  template<typename _InputIterator, typename _Predicate>
2122  _GLIBCXX20_CONSTEXPR
2123  typename iterator_traits<_InputIterator>::difference_type
2124  __count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
2125  {
2126  typename iterator_traits<_InputIterator>::difference_type __n = 0;
2127  for (; __first != __last; ++__first)
2128  if (__pred(__first))
2129  ++__n;
2130  return __n;
2131  }
2132 
2133  template<typename _ForwardIterator, typename _Predicate>
2134  _GLIBCXX20_CONSTEXPR
2135  _ForwardIterator
2136  __remove_if(_ForwardIterator __first, _ForwardIterator __last,
2137  _Predicate __pred)
2138  {
2139  __first = std::__find_if(__first, __last, __pred);
2140  if (__first == __last)
2141  return __first;
2142  _ForwardIterator __result = __first;
2143  ++__first;
2144  for (; __first != __last; ++__first)
2145  if (!__pred(__first))
2146  {
2147  *__result = _GLIBCXX_MOVE(*__first);
2148  ++__result;
2149  }
2150  return __result;
2151  }
2152 
2153 #if __cplusplus >= 201103L
2154  template<typename _ForwardIterator1, typename _ForwardIterator2,
2155  typename _BinaryPredicate>
2156  _GLIBCXX20_CONSTEXPR
2157  bool
2158  __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2159  _ForwardIterator2 __first2, _BinaryPredicate __pred)
2160  {
2161  // Efficiently compare identical prefixes: O(N) if sequences
2162  // have the same elements in the same order.
2163  for (; __first1 != __last1; ++__first1, (void)++__first2)
2164  if (!__pred(__first1, __first2))
2165  break;
2166 
2167  if (__first1 == __last1)
2168  return true;
2169 
2170  // Establish __last2 assuming equal ranges by iterating over the
2171  // rest of the list.
2172  _ForwardIterator2 __last2 = __first2;
2173  std::advance(__last2, std::distance(__first1, __last1));
2174  for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
2175  {
2176  if (__scan != std::__find_if(__first1, __scan,
2177  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan)))
2178  continue; // We've seen this one before.
2179 
2180  auto __matches
2181  = std::__count_if(__first2, __last2,
2182  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan));
2183  if (0 == __matches ||
2184  std::__count_if(__scan, __last1,
2185  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan))
2186  != __matches)
2187  return false;
2188  }
2189  return true;
2190  }
2191 
2192  /**
2193  * @brief Checks whether a permutation of the second sequence is equal
2194  * to the first sequence.
2195  * @ingroup non_mutating_algorithms
2196  * @param __first1 Start of first range.
2197  * @param __last1 End of first range.
2198  * @param __first2 Start of second range.
2199  * @return true if there exists a permutation of the elements in the range
2200  * [__first2, __first2 + (__last1 - __first1)), beginning with
2201  * ForwardIterator2 begin, such that equal(__first1, __last1, begin)
2202  * returns true; otherwise, returns false.
2203  */
2204  template<typename _ForwardIterator1, typename _ForwardIterator2>
2205  _GLIBCXX20_CONSTEXPR
2206  inline bool
2207  is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2208  _ForwardIterator2 __first2)
2209  {
2210  // concept requirements
2211  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
2212  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
2213  __glibcxx_function_requires(_EqualOpConcept<
2214  typename iterator_traits<_ForwardIterator1>::value_type,
2215  typename iterator_traits<_ForwardIterator2>::value_type>)
2216  __glibcxx_requires_valid_range(__first1, __last1);
2217 
2218  return std::__is_permutation(__first1, __last1, __first2,
2219  __gnu_cxx::__ops::__iter_equal_to_iter());
2220  }
2221 #endif // C++11
2222 
2223 _GLIBCXX_END_NAMESPACE_VERSION
2224 } // namespace std
2225 
2226 // NB: This file is included within many other C++ includes, as a way
2227 // of getting the base algorithms. So, make sure that parallel bits
2228 // come in too if requested.
2229 #ifdef _GLIBCXX_PARALLEL
2230 # include <parallel/algobase.h>
2231 #endif
2232 
2233 #endif
std::move_backward
constexpr _BI2 move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
Moves the range [first,last) into result.
Definition: stl_algobase.h:885
std::output_iterator_tag
Marking output iterators.
Definition: stl_iterator_base_types.h:96
std::is_integral
is_integral
Definition: type_traits:413
std::advance
constexpr void advance(_InputIterator &__i, _Distance __n)
A generalization of pointer arithmetic.
Definition: stl_iterator_base_funcs.h:218
std::is_nothrow_copy_constructible
is_nothrow_copy_constructible
Definition: type_traits:1079
std::is_same
is_same
Definition: type_traits:635
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::same_as
concept same_as
[concept.same], concept same_as
Definition: concepts:63
std::__find_if
constexpr _InputIterator __find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred, input_iterator_tag)
This is an overload used by find algos for the Input Iterator case.
Definition: stl_algobase.h:2052
std::is_constant_evaluated
constexpr bool is_constant_evaluated() noexcept
Returns true only when called during constant evaluation.
Definition: type_traits:3541
std::ostreambuf_iterator
Provides output iterator semantics for streambufs.
Definition: iosfwd:128
std
ISO C++ entities toplevel namespace is std.
std::iter_swap
constexpr void iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
Swaps the contents of two iterators.
Definition: stl_algobase.h:152
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition: stl_iterator_base_funcs.h:147
std::char_traits
Basis for explicit traits specializations.
Definition: char_traits.h:323
std::__lg
constexpr int __lg(int __n)
This is a helper function for the sort routines and for random.tcc.
Definition: stl_algobase.h:1507
std::random_access_iterator_tag
Random-access iterators support a superset of bidirectional iterator operations.
Definition: stl_iterator_base_types.h:107
__gnu_debug::_Safe_iterator
Safe iterator wrapper.
Definition: boost_concept_check.h:60
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
std::input_iterator_tag
Marking input iterators.
Definition: stl_iterator_base_types.h:93
std::pair
Struct holding two objects of arbitrary type.
Definition: bits/stl_iterator.h:2619
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition: stl_iterator_base_types.h:238
std::iterator_traits
Traits class for iterators.
Definition: cpp_type_traits.h:425
std::_Deque_iterator
A deque::iterator.
Definition: stl_algobase.h:445
algobase.h
Parallel STL function calls corresponding to the stl_algobase.h header. The functions defined here ma...
std::equal
constexpr bool equal(_IIter1 __first1, _IIter1 __last1, _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
Tests a range for element-wise equality.
Definition: stl_algobase.h:1701
std::copy
constexpr _OI copy(_II __first, _II __last, _OI __result)
Copies the range [first,last) into result.
Definition: stl_algobase.h:617
std::istreambuf_iterator
Provides input iterator semantics for streambufs.
Definition: iosfwd:125
std::max
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:254