libstdc++
stl_algobase.h
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1 // Core algorithmic facilities -*- C++ -*-
2 
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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,
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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
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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 
393 #if __cplusplus >= 201103L
394  template<>
395  struct __copy_move<true, false, random_access_iterator_tag>
396  {
397  template<typename _II, typename _OI>
398  _GLIBCXX20_CONSTEXPR
399  static _OI
400  __copy_m(_II __first, _II __last, _OI __result)
401  {
402  typedef typename iterator_traits<_II>::difference_type _Distance;
403  for(_Distance __n = __last - __first; __n > 0; --__n)
404  {
405  *__result = std::move(*__first);
406  ++__first;
407  ++__result;
408  }
409  return __result;
410  }
411  };
412 #endif
413 
414  template<bool _IsMove>
415  struct __copy_move<_IsMove, true, random_access_iterator_tag>
416  {
417  template<typename _Tp>
418  _GLIBCXX20_CONSTEXPR
419  static _Tp*
420  __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
421  {
422 #if __cplusplus >= 201103L
423  using __assignable = __conditional_t<_IsMove,
424  is_move_assignable<_Tp>,
425  is_copy_assignable<_Tp>>;
426  // trivial types can have deleted assignment
427  static_assert( __assignable::value, "type must be assignable" );
428 #endif
429  const ptrdiff_t _Num = __last - __first;
430  if (_Num)
431  __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
432  return __result + _Num;
433  }
434  };
435 
436 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
437 
438  template<typename _Tp, typename _Ref, typename _Ptr>
439  struct _Deque_iterator;
440 
441  struct _Bit_iterator;
442 
443 _GLIBCXX_END_NAMESPACE_CONTAINER
444 
445  // Helpers for streambuf iterators (either istream or ostream).
446  // NB: avoid including <iosfwd>, relatively large.
447  template<typename _CharT>
448  struct char_traits;
449 
450  template<typename _CharT, typename _Traits>
451  class istreambuf_iterator;
452 
453  template<typename _CharT, typename _Traits>
454  class ostreambuf_iterator;
455 
456  template<bool _IsMove, typename _CharT>
457  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
458  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
459  __copy_move_a2(_CharT*, _CharT*,
460  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
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(const _CharT*, const _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  _CharT*>::__type
471  __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
472  istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
473 
474  template<bool _IsMove, typename _CharT>
475  typename __gnu_cxx::__enable_if<
476  __is_char<_CharT>::__value,
477  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
478  __copy_move_a2(
479  istreambuf_iterator<_CharT, char_traits<_CharT> >,
480  istreambuf_iterator<_CharT, char_traits<_CharT> >,
481  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>);
482 
483  template<bool _IsMove, typename _II, typename _OI>
484  _GLIBCXX20_CONSTEXPR
485  inline _OI
486  __copy_move_a2(_II __first, _II __last, _OI __result)
487  {
488  typedef typename iterator_traits<_II>::iterator_category _Category;
489 #ifdef __cpp_lib_is_constant_evaluated
490  if (std::is_constant_evaluated())
491  return std::__copy_move<_IsMove, false, _Category>::
492  __copy_m(__first, __last, __result);
493 #endif
494  return std::__copy_move<_IsMove, __memcpyable<_OI, _II>::__value,
495  _Category>::__copy_m(__first, __last, __result);
496  }
497 
498  template<bool _IsMove,
499  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
500  _OI
501  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
502  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
503  _OI);
504 
505  template<bool _IsMove,
506  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
507  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
508  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
509  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
510  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
511 
512  template<bool _IsMove, typename _II, typename _Tp>
513  typename __gnu_cxx::__enable_if<
514  __is_random_access_iter<_II>::__value,
515  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
516  __copy_move_a1(_II, _II, _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
517 
518  template<bool _IsMove, typename _II, typename _OI>
519  _GLIBCXX20_CONSTEXPR
520  inline _OI
521  __copy_move_a1(_II __first, _II __last, _OI __result)
522  { return std::__copy_move_a2<_IsMove>(__first, __last, __result); }
523 
524  template<bool _IsMove, typename _II, typename _OI>
525  _GLIBCXX20_CONSTEXPR
526  inline _OI
527  __copy_move_a(_II __first, _II __last, _OI __result)
528  {
529  return std::__niter_wrap(__result,
530  std::__copy_move_a1<_IsMove>(std::__niter_base(__first),
531  std::__niter_base(__last),
532  std::__niter_base(__result)));
533  }
534 
535  template<bool _IsMove,
536  typename _Ite, typename _Seq, typename _Cat, typename _OI>
537  _OI
538  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
539  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
540  _OI);
541 
542  template<bool _IsMove,
543  typename _II, typename _Ite, typename _Seq, typename _Cat>
544  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
545  __copy_move_a(_II, _II,
546  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
547 
548  template<bool _IsMove,
549  typename _IIte, typename _ISeq, typename _ICat,
550  typename _OIte, typename _OSeq, typename _OCat>
551  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
552  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
553  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
554  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
555 
556  template<typename _InputIterator, typename _Size, typename _OutputIterator>
557  _GLIBCXX20_CONSTEXPR
558  _OutputIterator
559  __copy_n_a(_InputIterator __first, _Size __n, _OutputIterator __result,
560  bool)
561  {
562  if (__n > 0)
563  {
564  while (true)
565  {
566  *__result = *__first;
567  ++__result;
568  if (--__n > 0)
569  ++__first;
570  else
571  break;
572  }
573  }
574  return __result;
575  }
576 
577  template<typename _CharT, typename _Size>
578  typename __gnu_cxx::__enable_if<
579  __is_char<_CharT>::__value, _CharT*>::__type
580  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >,
581  _Size, _CharT*, bool);
582 
583  template<typename _CharT, typename _Size>
584  typename __gnu_cxx::__enable_if<
585  __is_char<_CharT>::__value,
586  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
587  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >, _Size,
588  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>,
589  bool);
590 
591  /**
592  * @brief Copies the range [first,last) into result.
593  * @ingroup mutating_algorithms
594  * @param __first An input iterator.
595  * @param __last An input iterator.
596  * @param __result An output iterator.
597  * @return result + (last - first)
598  *
599  * This inline function will boil down to a call to @c memmove whenever
600  * possible. Failing that, if random access iterators are passed, then the
601  * loop count will be known (and therefore a candidate for compiler
602  * optimizations such as unrolling). Result may not be contained within
603  * [first,last); the copy_backward function should be used instead.
604  *
605  * Note that the end of the output range is permitted to be contained
606  * within [first,last).
607  */
608  template<typename _II, typename _OI>
609  _GLIBCXX20_CONSTEXPR
610  inline _OI
611  copy(_II __first, _II __last, _OI __result)
612  {
613  // concept requirements
614  __glibcxx_function_requires(_InputIteratorConcept<_II>)
615  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
616  typename iterator_traits<_II>::reference>)
617  __glibcxx_requires_can_increment_range(__first, __last, __result);
618 
619  return std::__copy_move_a<__is_move_iterator<_II>::__value>
620  (std::__miter_base(__first), std::__miter_base(__last), __result);
621  }
622 
623 #if __cplusplus >= 201103L
624  /**
625  * @brief Moves the range [first,last) into result.
626  * @ingroup mutating_algorithms
627  * @param __first An input iterator.
628  * @param __last An input iterator.
629  * @param __result An output iterator.
630  * @return result + (last - first)
631  *
632  * This inline function will boil down to a call to @c memmove whenever
633  * possible. Failing that, if random access iterators are passed, then the
634  * loop count will be known (and therefore a candidate for compiler
635  * optimizations such as unrolling). Result may not be contained within
636  * [first,last); the move_backward function should be used instead.
637  *
638  * Note that the end of the output range is permitted to be contained
639  * within [first,last).
640  */
641  template<typename _II, typename _OI>
642  _GLIBCXX20_CONSTEXPR
643  inline _OI
644  move(_II __first, _II __last, _OI __result)
645  {
646  // concept requirements
647  __glibcxx_function_requires(_InputIteratorConcept<_II>)
648  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
649  typename iterator_traits<_II>::value_type&&>)
650  __glibcxx_requires_can_increment_range(__first, __last, __result);
651 
652  return std::__copy_move_a<true>(std::__miter_base(__first),
653  std::__miter_base(__last), __result);
654  }
655 
656 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
657 #else
658 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
659 #endif
660 
661  template<bool _IsMove, bool _IsSimple, typename _Category>
662  struct __copy_move_backward
663  {
664  template<typename _BI1, typename _BI2>
665  _GLIBCXX20_CONSTEXPR
666  static _BI2
667  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
668  {
669  while (__first != __last)
670  *--__result = *--__last;
671  return __result;
672  }
673  };
674 
675 #if __cplusplus >= 201103L
676  template<typename _Category>
677  struct __copy_move_backward<true, false, _Category>
678  {
679  template<typename _BI1, typename _BI2>
680  _GLIBCXX20_CONSTEXPR
681  static _BI2
682  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
683  {
684  while (__first != __last)
685  *--__result = std::move(*--__last);
686  return __result;
687  }
688  };
689 #endif
690 
691  template<>
692  struct __copy_move_backward<false, false, random_access_iterator_tag>
693  {
694  template<typename _BI1, typename _BI2>
695  _GLIBCXX20_CONSTEXPR
696  static _BI2
697  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
698  {
699  typename iterator_traits<_BI1>::difference_type
700  __n = __last - __first;
701  for (; __n > 0; --__n)
702  *--__result = *--__last;
703  return __result;
704  }
705  };
706 
707 #if __cplusplus >= 201103L
708  template<>
709  struct __copy_move_backward<true, false, random_access_iterator_tag>
710  {
711  template<typename _BI1, typename _BI2>
712  _GLIBCXX20_CONSTEXPR
713  static _BI2
714  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
715  {
716  typename iterator_traits<_BI1>::difference_type
717  __n = __last - __first;
718  for (; __n > 0; --__n)
719  *--__result = std::move(*--__last);
720  return __result;
721  }
722  };
723 #endif
724 
725  template<bool _IsMove>
726  struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
727  {
728  template<typename _Tp>
729  _GLIBCXX20_CONSTEXPR
730  static _Tp*
731  __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
732  {
733 #if __cplusplus >= 201103L
734  using __assignable = __conditional_t<_IsMove,
735  is_move_assignable<_Tp>,
736  is_copy_assignable<_Tp>>;
737  // trivial types can have deleted assignment
738  static_assert( __assignable::value, "type must be assignable" );
739 #endif
740  const ptrdiff_t _Num = __last - __first;
741  if (_Num)
742  __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
743  return __result - _Num;
744  }
745  };
746 
747  template<bool _IsMove, typename _BI1, typename _BI2>
748  _GLIBCXX20_CONSTEXPR
749  inline _BI2
750  __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
751  {
752  typedef typename iterator_traits<_BI1>::iterator_category _Category;
753 #ifdef __cpp_lib_is_constant_evaluated
754  if (std::is_constant_evaluated())
755  return std::__copy_move_backward<_IsMove, false, _Category>::
756  __copy_move_b(__first, __last, __result);
757 #endif
758  return std::__copy_move_backward<_IsMove,
759  __memcpyable<_BI2, _BI1>::__value,
760  _Category>::__copy_move_b(__first,
761  __last,
762  __result);
763  }
764 
765  template<bool _IsMove, typename _BI1, typename _BI2>
766  _GLIBCXX20_CONSTEXPR
767  inline _BI2
768  __copy_move_backward_a1(_BI1 __first, _BI1 __last, _BI2 __result)
769  { return std::__copy_move_backward_a2<_IsMove>(__first, __last, __result); }
770 
771  template<bool _IsMove,
772  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
773  _OI
774  __copy_move_backward_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
775  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
776  _OI);
777 
778  template<bool _IsMove,
779  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
780  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
781  __copy_move_backward_a1(
782  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
783  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
784  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
785 
786  template<bool _IsMove, typename _II, typename _Tp>
787  typename __gnu_cxx::__enable_if<
788  __is_random_access_iter<_II>::__value,
789  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
790  __copy_move_backward_a1(_II, _II,
791  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
792 
793  template<bool _IsMove, typename _II, typename _OI>
794  _GLIBCXX20_CONSTEXPR
795  inline _OI
796  __copy_move_backward_a(_II __first, _II __last, _OI __result)
797  {
798  return std::__niter_wrap(__result,
799  std::__copy_move_backward_a1<_IsMove>
800  (std::__niter_base(__first), std::__niter_base(__last),
801  std::__niter_base(__result)));
802  }
803 
804  template<bool _IsMove,
805  typename _Ite, typename _Seq, typename _Cat, typename _OI>
806  _OI
807  __copy_move_backward_a(
808  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
809  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
810  _OI);
811 
812  template<bool _IsMove,
813  typename _II, typename _Ite, typename _Seq, typename _Cat>
814  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
815  __copy_move_backward_a(_II, _II,
816  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
817 
818  template<bool _IsMove,
819  typename _IIte, typename _ISeq, typename _ICat,
820  typename _OIte, typename _OSeq, typename _OCat>
821  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
822  __copy_move_backward_a(
823  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
824  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
825  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
826 
827  /**
828  * @brief Copies the range [first,last) into result.
829  * @ingroup mutating_algorithms
830  * @param __first A bidirectional iterator.
831  * @param __last A bidirectional iterator.
832  * @param __result A bidirectional iterator.
833  * @return result - (last - first)
834  *
835  * The function has the same effect as copy, but starts at the end of the
836  * range and works its way to the start, returning the start of the result.
837  * This inline function will boil down to a call to @c memmove whenever
838  * possible. Failing that, if random access iterators are passed, then the
839  * loop count will be known (and therefore a candidate for compiler
840  * optimizations such as unrolling).
841  *
842  * Result may not be in the range (first,last]. Use copy instead. Note
843  * that the start of the output range may overlap [first,last).
844  */
845  template<typename _BI1, typename _BI2>
846  _GLIBCXX20_CONSTEXPR
847  inline _BI2
848  copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
849  {
850  // concept requirements
851  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
852  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
853  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
854  typename iterator_traits<_BI1>::reference>)
855  __glibcxx_requires_can_decrement_range(__first, __last, __result);
856 
857  return std::__copy_move_backward_a<__is_move_iterator<_BI1>::__value>
858  (std::__miter_base(__first), std::__miter_base(__last), __result);
859  }
860 
861 #if __cplusplus >= 201103L
862  /**
863  * @brief Moves the range [first,last) into result.
864  * @ingroup mutating_algorithms
865  * @param __first A bidirectional iterator.
866  * @param __last A bidirectional iterator.
867  * @param __result A bidirectional iterator.
868  * @return result - (last - first)
869  *
870  * The function has the same effect as move, but starts at the end of the
871  * range and works its way to the start, returning the start of the result.
872  * This inline function will boil down to a call to @c memmove whenever
873  * possible. Failing that, if random access iterators are passed, then the
874  * loop count will be known (and therefore a candidate for compiler
875  * optimizations such as unrolling).
876  *
877  * Result may not be in the range (first,last]. Use move instead. Note
878  * that the start of the output range may overlap [first,last).
879  */
880  template<typename _BI1, typename _BI2>
881  _GLIBCXX20_CONSTEXPR
882  inline _BI2
883  move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
884  {
885  // concept requirements
886  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
887  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
888  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
889  typename iterator_traits<_BI1>::value_type&&>)
890  __glibcxx_requires_can_decrement_range(__first, __last, __result);
891 
892  return std::__copy_move_backward_a<true>(std::__miter_base(__first),
893  std::__miter_base(__last),
894  __result);
895  }
896 
897 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
898 #else
899 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
900 #endif
901 
902  template<typename _ForwardIterator, typename _Tp>
903  _GLIBCXX20_CONSTEXPR
904  inline typename
905  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
906  __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
907  const _Tp& __value)
908  {
909  for (; __first != __last; ++__first)
910  *__first = __value;
911  }
912 
913  template<typename _ForwardIterator, typename _Tp>
914  _GLIBCXX20_CONSTEXPR
915  inline typename
916  __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
917  __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
918  const _Tp& __value)
919  {
920  const _Tp __tmp = __value;
921  for (; __first != __last; ++__first)
922  *__first = __tmp;
923  }
924 
925  // Specialization: for char types we can use memset.
926  template<typename _Tp>
927  _GLIBCXX20_CONSTEXPR
928  inline typename
929  __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
930  __fill_a1(_Tp* __first, _Tp* __last, const _Tp& __c)
931  {
932  const _Tp __tmp = __c;
933 #if __cpp_lib_is_constant_evaluated
934  if (std::is_constant_evaluated())
935  {
936  for (; __first != __last; ++__first)
937  *__first = __tmp;
938  return;
939  }
940 #endif
941  if (const size_t __len = __last - __first)
942  __builtin_memset(__first, static_cast<unsigned char>(__tmp), __len);
943  }
944 
945  template<typename _Ite, typename _Cont, typename _Tp>
946  _GLIBCXX20_CONSTEXPR
947  inline void
948  __fill_a1(::__gnu_cxx::__normal_iterator<_Ite, _Cont> __first,
949  ::__gnu_cxx::__normal_iterator<_Ite, _Cont> __last,
950  const _Tp& __value)
951  { std::__fill_a1(__first.base(), __last.base(), __value); }
952 
953  template<typename _Tp, typename _VTp>
954  void
955  __fill_a1(const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
956  const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
957  const _VTp&);
958 
959  _GLIBCXX20_CONSTEXPR
960  void
961  __fill_a1(_GLIBCXX_STD_C::_Bit_iterator, _GLIBCXX_STD_C::_Bit_iterator,
962  const bool&);
963 
964  template<typename _FIte, typename _Tp>
965  _GLIBCXX20_CONSTEXPR
966  inline void
967  __fill_a(_FIte __first, _FIte __last, const _Tp& __value)
968  { std::__fill_a1(__first, __last, __value); }
969 
970  template<typename _Ite, typename _Seq, typename _Cat, typename _Tp>
971  void
972  __fill_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
973  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
974  const _Tp&);
975 
976  /**
977  * @brief Fills the range [first,last) with copies of value.
978  * @ingroup mutating_algorithms
979  * @param __first A forward iterator.
980  * @param __last A forward iterator.
981  * @param __value A reference-to-const of arbitrary type.
982  * @return Nothing.
983  *
984  * This function fills a range with copies of the same value. For char
985  * types filling contiguous areas of memory, this becomes an inline call
986  * to @c memset or @c wmemset.
987  */
988  template<typename _ForwardIterator, typename _Tp>
989  _GLIBCXX20_CONSTEXPR
990  inline void
991  fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
992  {
993  // concept requirements
994  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
995  _ForwardIterator>)
996  __glibcxx_requires_valid_range(__first, __last);
997 
998  std::__fill_a(__first, __last, __value);
999  }
1000 
1001  // Used by fill_n, generate_n, etc. to convert _Size to an integral type:
1002  inline _GLIBCXX_CONSTEXPR int
1003  __size_to_integer(int __n) { return __n; }
1004  inline _GLIBCXX_CONSTEXPR unsigned
1005  __size_to_integer(unsigned __n) { return __n; }
1006  inline _GLIBCXX_CONSTEXPR long
1007  __size_to_integer(long __n) { return __n; }
1008  inline _GLIBCXX_CONSTEXPR unsigned long
1009  __size_to_integer(unsigned long __n) { return __n; }
1010  inline _GLIBCXX_CONSTEXPR long long
1011  __size_to_integer(long long __n) { return __n; }
1012  inline _GLIBCXX_CONSTEXPR unsigned long long
1013  __size_to_integer(unsigned long long __n) { return __n; }
1014 
1015 #if defined(__GLIBCXX_TYPE_INT_N_0)
1016  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_0
1017  __size_to_integer(__GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1018  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_0
1019  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1020 #endif
1021 #if defined(__GLIBCXX_TYPE_INT_N_1)
1022  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_1
1023  __size_to_integer(__GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1024  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_1
1025  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1026 #endif
1027 #if defined(__GLIBCXX_TYPE_INT_N_2)
1028  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_2
1029  __size_to_integer(__GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1030  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_2
1031  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1032 #endif
1033 #if defined(__GLIBCXX_TYPE_INT_N_3)
1034  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_3
1035  __size_to_integer(__GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1036  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_3
1037  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1038 #endif
1039 
1040  inline _GLIBCXX_CONSTEXPR long long
1041  __size_to_integer(float __n) { return (long long)__n; }
1042  inline _GLIBCXX_CONSTEXPR long long
1043  __size_to_integer(double __n) { return (long long)__n; }
1044  inline _GLIBCXX_CONSTEXPR long long
1045  __size_to_integer(long double __n) { return (long long)__n; }
1046 #if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128)
1047  __extension__ inline _GLIBCXX_CONSTEXPR long long
1048  __size_to_integer(__float128 __n) { return (long long)__n; }
1049 #endif
1050 
1051  template<typename _OutputIterator, typename _Size, typename _Tp>
1052  _GLIBCXX20_CONSTEXPR
1053  inline typename
1054  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
1055  __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
1056  {
1057  for (; __n > 0; --__n, (void) ++__first)
1058  *__first = __value;
1059  return __first;
1060  }
1061 
1062  template<typename _OutputIterator, typename _Size, typename _Tp>
1063  _GLIBCXX20_CONSTEXPR
1064  inline typename
1065  __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
1066  __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
1067  {
1068  const _Tp __tmp = __value;
1069  for (; __n > 0; --__n, (void) ++__first)
1070  *__first = __tmp;
1071  return __first;
1072  }
1073 
1074  template<typename _Ite, typename _Seq, typename _Cat, typename _Size,
1075  typename _Tp>
1076  ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
1077  __fill_n_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>& __first,
1078  _Size __n, const _Tp& __value,
1079  std::input_iterator_tag);
1080 
1081  template<typename _OutputIterator, typename _Size, typename _Tp>
1082  _GLIBCXX20_CONSTEXPR
1083  inline _OutputIterator
1084  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1085  std::output_iterator_tag)
1086  {
1087 #if __cplusplus >= 201103L
1088  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1089 #endif
1090  return __fill_n_a1(__first, __n, __value);
1091  }
1092 
1093  template<typename _OutputIterator, typename _Size, typename _Tp>
1094  _GLIBCXX20_CONSTEXPR
1095  inline _OutputIterator
1096  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1097  std::input_iterator_tag)
1098  {
1099 #if __cplusplus >= 201103L
1100  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1101 #endif
1102  return __fill_n_a1(__first, __n, __value);
1103  }
1104 
1105  template<typename _OutputIterator, typename _Size, typename _Tp>
1106  _GLIBCXX20_CONSTEXPR
1107  inline _OutputIterator
1108  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1109  std::random_access_iterator_tag)
1110  {
1111 #if __cplusplus >= 201103L
1112  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1113 #endif
1114  if (__n <= 0)
1115  return __first;
1116 
1117  __glibcxx_requires_can_increment(__first, __n);
1118 
1119  std::__fill_a(__first, __first + __n, __value);
1120  return __first + __n;
1121  }
1122 
1123  /**
1124  * @brief Fills the range [first,first+n) with copies of value.
1125  * @ingroup mutating_algorithms
1126  * @param __first An output iterator.
1127  * @param __n The count of copies to perform.
1128  * @param __value A reference-to-const of arbitrary type.
1129  * @return The iterator at first+n.
1130  *
1131  * This function fills a range with copies of the same value. For char
1132  * types filling contiguous areas of memory, this becomes an inline call
1133  * to @c memset or @c wmemset.
1134  *
1135  * If @p __n is negative, the function does nothing.
1136  */
1137  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1138  // DR 865. More algorithms that throw away information
1139  // DR 426. search_n(), fill_n(), and generate_n() with negative n
1140  template<typename _OI, typename _Size, typename _Tp>
1141  _GLIBCXX20_CONSTEXPR
1142  inline _OI
1143  fill_n(_OI __first, _Size __n, const _Tp& __value)
1144  {
1145  // concept requirements
1146  __glibcxx_function_requires(_OutputIteratorConcept<_OI, const _Tp&>)
1147 
1148  return std::__fill_n_a(__first, std::__size_to_integer(__n), __value,
1149  std::__iterator_category(__first));
1150  }
1151 
1152  template<bool _BoolType>
1153  struct __equal
1154  {
1155  template<typename _II1, typename _II2>
1156  _GLIBCXX20_CONSTEXPR
1157  static bool
1158  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1159  {
1160  for (; __first1 != __last1; ++__first1, (void) ++__first2)
1161  if (!(*__first1 == *__first2))
1162  return false;
1163  return true;
1164  }
1165  };
1166 
1167  template<>
1168  struct __equal<true>
1169  {
1170  template<typename _Tp>
1171  _GLIBCXX20_CONSTEXPR
1172  static bool
1173  equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
1174  {
1175  if (const size_t __len = (__last1 - __first1))
1176  return !std::__memcmp(__first1, __first2, __len);
1177  return true;
1178  }
1179  };
1180 
1181  template<typename _Tp, typename _Ref, typename _Ptr, typename _II>
1182  typename __gnu_cxx::__enable_if<
1183  __is_random_access_iter<_II>::__value, bool>::__type
1184  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1185  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1186  _II);
1187 
1188  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1189  typename _Tp2, typename _Ref2, typename _Ptr2>
1190  bool
1191  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1192  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1193  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1194 
1195  template<typename _II, typename _Tp, typename _Ref, typename _Ptr>
1196  typename __gnu_cxx::__enable_if<
1197  __is_random_access_iter<_II>::__value, bool>::__type
1198  __equal_aux1(_II, _II,
1199  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>);
1200 
1201  template<typename _II1, typename _II2>
1202  _GLIBCXX20_CONSTEXPR
1203  inline bool
1204  __equal_aux1(_II1 __first1, _II1 __last1, _II2 __first2)
1205  {
1206  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1207  const bool __simple = ((__is_integer<_ValueType1>::__value
1208  || __is_pointer<_ValueType1>::__value)
1209  && __memcmpable<_II1, _II2>::__value);
1210  return std::__equal<__simple>::equal(__first1, __last1, __first2);
1211  }
1212 
1213  template<typename _II1, typename _II2>
1214  _GLIBCXX20_CONSTEXPR
1215  inline bool
1216  __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
1217  {
1218  return std::__equal_aux1(std::__niter_base(__first1),
1219  std::__niter_base(__last1),
1220  std::__niter_base(__first2));
1221  }
1222 
1223  template<typename _II1, typename _Seq1, typename _Cat1, typename _II2>
1224  bool
1225  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1226  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1227  _II2);
1228 
1229  template<typename _II1, typename _II2, typename _Seq2, typename _Cat2>
1230  bool
1231  __equal_aux(_II1, _II1,
1232  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1233 
1234  template<typename _II1, typename _Seq1, typename _Cat1,
1235  typename _II2, typename _Seq2, typename _Cat2>
1236  bool
1237  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1238  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1239  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1240 
1241  template<typename, typename>
1242  struct __lc_rai
1243  {
1244  template<typename _II1, typename _II2>
1245  _GLIBCXX20_CONSTEXPR
1246  static _II1
1247  __newlast1(_II1, _II1 __last1, _II2, _II2)
1248  { return __last1; }
1249 
1250  template<typename _II>
1251  _GLIBCXX20_CONSTEXPR
1252  static bool
1253  __cnd2(_II __first, _II __last)
1254  { return __first != __last; }
1255  };
1256 
1257  template<>
1258  struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
1259  {
1260  template<typename _RAI1, typename _RAI2>
1261  _GLIBCXX20_CONSTEXPR
1262  static _RAI1
1263  __newlast1(_RAI1 __first1, _RAI1 __last1,
1264  _RAI2 __first2, _RAI2 __last2)
1265  {
1266  const typename iterator_traits<_RAI1>::difference_type
1267  __diff1 = __last1 - __first1;
1268  const typename iterator_traits<_RAI2>::difference_type
1269  __diff2 = __last2 - __first2;
1270  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
1271  }
1272 
1273  template<typename _RAI>
1274  static _GLIBCXX20_CONSTEXPR bool
1275  __cnd2(_RAI, _RAI)
1276  { return true; }
1277  };
1278 
1279  template<typename _II1, typename _II2, typename _Compare>
1280  _GLIBCXX20_CONSTEXPR
1281  bool
1282  __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
1283  _II2 __first2, _II2 __last2,
1284  _Compare __comp)
1285  {
1286  typedef typename iterator_traits<_II1>::iterator_category _Category1;
1287  typedef typename iterator_traits<_II2>::iterator_category _Category2;
1288  typedef std::__lc_rai<_Category1, _Category2> __rai_type;
1289 
1290  __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1291  for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1292  ++__first1, (void)++__first2)
1293  {
1294  if (__comp(__first1, __first2))
1295  return true;
1296  if (__comp(__first2, __first1))
1297  return false;
1298  }
1299  return __first1 == __last1 && __first2 != __last2;
1300  }
1301 
1302  template<bool _BoolType>
1303  struct __lexicographical_compare
1304  {
1305  template<typename _II1, typename _II2>
1306  _GLIBCXX20_CONSTEXPR
1307  static bool
1308  __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1309  {
1310  using __gnu_cxx::__ops::__iter_less_iter;
1311  return std::__lexicographical_compare_impl(__first1, __last1,
1312  __first2, __last2,
1313  __iter_less_iter());
1314  }
1315 
1316  template<typename _II1, typename _II2>
1317  _GLIBCXX20_CONSTEXPR
1318  static int
1319  __3way(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1320  {
1321  while (__first1 != __last1)
1322  {
1323  if (__first2 == __last2)
1324  return +1;
1325  if (*__first1 < *__first2)
1326  return -1;
1327  if (*__first2 < *__first1)
1328  return +1;
1329  ++__first1;
1330  ++__first2;
1331  }
1332  return int(__first2 == __last2) - 1;
1333  }
1334  };
1335 
1336  template<>
1337  struct __lexicographical_compare<true>
1338  {
1339  template<typename _Tp, typename _Up>
1340  _GLIBCXX20_CONSTEXPR
1341  static bool
1342  __lc(const _Tp* __first1, const _Tp* __last1,
1343  const _Up* __first2, const _Up* __last2)
1344  { return __3way(__first1, __last1, __first2, __last2) < 0; }
1345 
1346  template<typename _Tp, typename _Up>
1347  _GLIBCXX20_CONSTEXPR
1348  static ptrdiff_t
1349  __3way(const _Tp* __first1, const _Tp* __last1,
1350  const _Up* __first2, const _Up* __last2)
1351  {
1352  const size_t __len1 = __last1 - __first1;
1353  const size_t __len2 = __last2 - __first2;
1354  if (const size_t __len = std::min(__len1, __len2))
1355  if (int __result = std::__memcmp(__first1, __first2, __len))
1356  return __result;
1357  return ptrdiff_t(__len1 - __len2);
1358  }
1359  };
1360 
1361  template<typename _II1, typename _II2>
1362  _GLIBCXX20_CONSTEXPR
1363  inline bool
1364  __lexicographical_compare_aux1(_II1 __first1, _II1 __last1,
1365  _II2 __first2, _II2 __last2)
1366  {
1367  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1368  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1369  const bool __simple =
1370  (__is_memcmp_ordered_with<_ValueType1, _ValueType2>::__value
1371  && __is_pointer<_II1>::__value
1372  && __is_pointer<_II2>::__value
1373 #if __cplusplus > 201703L && __cpp_lib_concepts
1374  // For C++20 iterator_traits<volatile T*>::value_type is non-volatile
1375  // so __is_byte<T> could be true, but we can't use memcmp with
1376  // volatile data.
1377  && !is_volatile_v<remove_reference_t<iter_reference_t<_II1>>>
1378  && !is_volatile_v<remove_reference_t<iter_reference_t<_II2>>>
1379 #endif
1380  );
1381 
1382  return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
1383  __first2, __last2);
1384  }
1385 
1386  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1387  typename _Tp2>
1388  bool
1389  __lexicographical_compare_aux1(
1390  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1391  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1392  _Tp2*, _Tp2*);
1393 
1394  template<typename _Tp1,
1395  typename _Tp2, typename _Ref2, typename _Ptr2>
1396  bool
1397  __lexicographical_compare_aux1(_Tp1*, _Tp1*,
1398  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1399  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1400 
1401  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1402  typename _Tp2, typename _Ref2, typename _Ptr2>
1403  bool
1404  __lexicographical_compare_aux1(
1405  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1406  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1407  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1408  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1409 
1410  template<typename _II1, typename _II2>
1411  _GLIBCXX20_CONSTEXPR
1412  inline bool
1413  __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
1414  _II2 __first2, _II2 __last2)
1415  {
1416  return std::__lexicographical_compare_aux1(std::__niter_base(__first1),
1417  std::__niter_base(__last1),
1418  std::__niter_base(__first2),
1419  std::__niter_base(__last2));
1420  }
1421 
1422  template<typename _Iter1, typename _Seq1, typename _Cat1,
1423  typename _II2>
1424  bool
1425  __lexicographical_compare_aux(
1426  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1427  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1428  _II2, _II2);
1429 
1430  template<typename _II1,
1431  typename _Iter2, typename _Seq2, typename _Cat2>
1432  bool
1433  __lexicographical_compare_aux(
1434  _II1, _II1,
1435  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1436  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1437 
1438  template<typename _Iter1, typename _Seq1, typename _Cat1,
1439  typename _Iter2, typename _Seq2, typename _Cat2>
1440  bool
1441  __lexicographical_compare_aux(
1442  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1443  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1444  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1445  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1446 
1447  template<typename _ForwardIterator, typename _Tp, typename _Compare>
1448  _GLIBCXX20_CONSTEXPR
1449  _ForwardIterator
1450  __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1451  const _Tp& __val, _Compare __comp)
1452  {
1453  typedef typename iterator_traits<_ForwardIterator>::difference_type
1454  _DistanceType;
1455 
1456  _DistanceType __len = std::distance(__first, __last);
1457 
1458  while (__len > 0)
1459  {
1460  _DistanceType __half = __len >> 1;
1461  _ForwardIterator __middle = __first;
1462  std::advance(__middle, __half);
1463  if (__comp(__middle, __val))
1464  {
1465  __first = __middle;
1466  ++__first;
1467  __len = __len - __half - 1;
1468  }
1469  else
1470  __len = __half;
1471  }
1472  return __first;
1473  }
1474 
1475  /**
1476  * @brief Finds the first position in which @a val could be inserted
1477  * without changing the ordering.
1478  * @param __first An iterator.
1479  * @param __last Another iterator.
1480  * @param __val The search term.
1481  * @return An iterator pointing to the first element <em>not less
1482  * than</em> @a val, or end() if every element is less than
1483  * @a val.
1484  * @ingroup binary_search_algorithms
1485  */
1486  template<typename _ForwardIterator, typename _Tp>
1487  _GLIBCXX20_CONSTEXPR
1488  inline _ForwardIterator
1489  lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1490  const _Tp& __val)
1491  {
1492  // concept requirements
1493  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
1494  __glibcxx_function_requires(_LessThanOpConcept<
1495  typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
1496  __glibcxx_requires_partitioned_lower(__first, __last, __val);
1497 
1498  return std::__lower_bound(__first, __last, __val,
1499  __gnu_cxx::__ops::__iter_less_val());
1500  }
1501 
1502  /// This is a helper function for the sort routines and for random.tcc.
1503  // Precondition: __n > 0.
1504  inline _GLIBCXX_CONSTEXPR int
1505  __lg(int __n)
1506  { return (int)sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
1507 
1508  inline _GLIBCXX_CONSTEXPR unsigned
1509  __lg(unsigned __n)
1510  { return (int)sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
1511 
1512  inline _GLIBCXX_CONSTEXPR long
1513  __lg(long __n)
1514  { return (int)sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1515 
1516  inline _GLIBCXX_CONSTEXPR unsigned long
1517  __lg(unsigned long __n)
1518  { return (int)sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1519 
1520  inline _GLIBCXX_CONSTEXPR long long
1521  __lg(long long __n)
1522  { return (int)sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1523 
1524  inline _GLIBCXX_CONSTEXPR unsigned long long
1525  __lg(unsigned long long __n)
1526  { return (int)sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1527 
1528 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1529 
1530  /**
1531  * @brief Tests a range for element-wise equality.
1532  * @ingroup non_mutating_algorithms
1533  * @param __first1 An input iterator.
1534  * @param __last1 An input iterator.
1535  * @param __first2 An input iterator.
1536  * @return A boolean true or false.
1537  *
1538  * This compares the elements of two ranges using @c == and returns true or
1539  * false depending on whether all of the corresponding elements of the
1540  * ranges are equal.
1541  */
1542  template<typename _II1, typename _II2>
1543  _GLIBCXX20_CONSTEXPR
1544  inline bool
1545  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1546  {
1547  // concept requirements
1548  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1549  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1550  __glibcxx_function_requires(_EqualOpConcept<
1551  typename iterator_traits<_II1>::value_type,
1552  typename iterator_traits<_II2>::value_type>)
1553  __glibcxx_requires_can_increment_range(__first1, __last1, __first2);
1554 
1555  return std::__equal_aux(__first1, __last1, __first2);
1556  }
1557 
1558  /**
1559  * @brief Tests a range for element-wise equality.
1560  * @ingroup non_mutating_algorithms
1561  * @param __first1 An input iterator.
1562  * @param __last1 An input iterator.
1563  * @param __first2 An input iterator.
1564  * @param __binary_pred A binary predicate @link functors
1565  * functor@endlink.
1566  * @return A boolean true or false.
1567  *
1568  * This compares the elements of two ranges using the binary_pred
1569  * parameter, and returns true or
1570  * false depending on whether all of the corresponding elements of the
1571  * ranges are equal.
1572  */
1573  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1574  _GLIBCXX20_CONSTEXPR
1575  inline bool
1576  equal(_IIter1 __first1, _IIter1 __last1,
1577  _IIter2 __first2, _BinaryPredicate __binary_pred)
1578  {
1579  // concept requirements
1580  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1581  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1582  __glibcxx_requires_valid_range(__first1, __last1);
1583 
1584  for (; __first1 != __last1; ++__first1, (void)++__first2)
1585  if (!bool(__binary_pred(*__first1, *__first2)))
1586  return false;
1587  return true;
1588  }
1589 
1590 #if __cplusplus >= 201103L
1591  // 4-iterator version of std::equal<It1, It2> for use in C++11.
1592  template<typename _II1, typename _II2>
1593  _GLIBCXX20_CONSTEXPR
1594  inline bool
1595  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1596  {
1597  using _RATag = random_access_iterator_tag;
1598  using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1599  using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1600  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1601  if (_RAIters())
1602  {
1603  auto __d1 = std::distance(__first1, __last1);
1604  auto __d2 = std::distance(__first2, __last2);
1605  if (__d1 != __d2)
1606  return false;
1607  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1608  }
1609 
1610  for (; __first1 != __last1 && __first2 != __last2;
1611  ++__first1, (void)++__first2)
1612  if (!(*__first1 == *__first2))
1613  return false;
1614  return __first1 == __last1 && __first2 == __last2;
1615  }
1616 
1617  // 4-iterator version of std::equal<It1, It2, BinaryPred> for use in C++11.
1618  template<typename _II1, typename _II2, typename _BinaryPredicate>
1619  _GLIBCXX20_CONSTEXPR
1620  inline bool
1621  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2,
1622  _BinaryPredicate __binary_pred)
1623  {
1624  using _RATag = random_access_iterator_tag;
1625  using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1626  using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1627  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1628  if (_RAIters())
1629  {
1630  auto __d1 = std::distance(__first1, __last1);
1631  auto __d2 = std::distance(__first2, __last2);
1632  if (__d1 != __d2)
1633  return false;
1634  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1635  __binary_pred);
1636  }
1637 
1638  for (; __first1 != __last1 && __first2 != __last2;
1639  ++__first1, (void)++__first2)
1640  if (!bool(__binary_pred(*__first1, *__first2)))
1641  return false;
1642  return __first1 == __last1 && __first2 == __last2;
1643  }
1644 #endif // C++11
1645 
1646 #if __cplusplus > 201103L
1647 
1648 #define __cpp_lib_robust_nonmodifying_seq_ops 201304L
1649 
1650  /**
1651  * @brief Tests a range for element-wise equality.
1652  * @ingroup non_mutating_algorithms
1653  * @param __first1 An input iterator.
1654  * @param __last1 An input iterator.
1655  * @param __first2 An input iterator.
1656  * @param __last2 An input iterator.
1657  * @return A boolean true or false.
1658  *
1659  * This compares the elements of two ranges using @c == and returns true or
1660  * false depending on whether all of the corresponding elements of the
1661  * ranges are equal.
1662  */
1663  template<typename _II1, typename _II2>
1664  _GLIBCXX20_CONSTEXPR
1665  inline bool
1666  equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1667  {
1668  // concept requirements
1669  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1670  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1671  __glibcxx_function_requires(_EqualOpConcept<
1672  typename iterator_traits<_II1>::value_type,
1673  typename iterator_traits<_II2>::value_type>)
1674  __glibcxx_requires_valid_range(__first1, __last1);
1675  __glibcxx_requires_valid_range(__first2, __last2);
1676 
1677  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2);
1678  }
1679 
1680  /**
1681  * @brief Tests a range for element-wise equality.
1682  * @ingroup non_mutating_algorithms
1683  * @param __first1 An input iterator.
1684  * @param __last1 An input iterator.
1685  * @param __first2 An input iterator.
1686  * @param __last2 An input iterator.
1687  * @param __binary_pred A binary predicate @link functors
1688  * functor@endlink.
1689  * @return A boolean true or false.
1690  *
1691  * This compares the elements of two ranges using the binary_pred
1692  * parameter, and returns true or
1693  * false depending on whether all of the corresponding elements of the
1694  * ranges are equal.
1695  */
1696  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1697  _GLIBCXX20_CONSTEXPR
1698  inline bool
1699  equal(_IIter1 __first1, _IIter1 __last1,
1700  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1701  {
1702  // concept requirements
1703  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1704  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1705  __glibcxx_requires_valid_range(__first1, __last1);
1706  __glibcxx_requires_valid_range(__first2, __last2);
1707 
1708  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2,
1709  __binary_pred);
1710  }
1711 #endif // C++14
1712 
1713  /**
1714  * @brief Performs @b dictionary comparison on ranges.
1715  * @ingroup sorting_algorithms
1716  * @param __first1 An input iterator.
1717  * @param __last1 An input iterator.
1718  * @param __first2 An input iterator.
1719  * @param __last2 An input iterator.
1720  * @return A boolean true or false.
1721  *
1722  * <em>Returns true if the sequence of elements defined by the range
1723  * [first1,last1) is lexicographically less than the sequence of elements
1724  * defined by the range [first2,last2). Returns false otherwise.</em>
1725  * (Quoted from [25.3.8]/1.) If the iterators are all character pointers,
1726  * then this is an inline call to @c memcmp.
1727  */
1728  template<typename _II1, typename _II2>
1729  _GLIBCXX20_CONSTEXPR
1730  inline bool
1731  lexicographical_compare(_II1 __first1, _II1 __last1,
1732  _II2 __first2, _II2 __last2)
1733  {
1734 #ifdef _GLIBCXX_CONCEPT_CHECKS
1735  // concept requirements
1736  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1737  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1738 #endif
1739  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1740  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1741  __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1742  __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1743  __glibcxx_requires_valid_range(__first1, __last1);
1744  __glibcxx_requires_valid_range(__first2, __last2);
1745 
1746  return std::__lexicographical_compare_aux(__first1, __last1,
1747  __first2, __last2);
1748  }
1749 
1750  /**
1751  * @brief Performs @b dictionary comparison on ranges.
1752  * @ingroup sorting_algorithms
1753  * @param __first1 An input iterator.
1754  * @param __last1 An input iterator.
1755  * @param __first2 An input iterator.
1756  * @param __last2 An input iterator.
1757  * @param __comp A @link comparison_functors comparison functor@endlink.
1758  * @return A boolean true or false.
1759  *
1760  * The same as the four-parameter @c lexicographical_compare, but uses the
1761  * comp parameter instead of @c <.
1762  */
1763  template<typename _II1, typename _II2, typename _Compare>
1764  _GLIBCXX20_CONSTEXPR
1765  inline bool
1766  lexicographical_compare(_II1 __first1, _II1 __last1,
1767  _II2 __first2, _II2 __last2, _Compare __comp)
1768  {
1769  // concept requirements
1770  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1771  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1772  __glibcxx_requires_valid_range(__first1, __last1);
1773  __glibcxx_requires_valid_range(__first2, __last2);
1774 
1775  return std::__lexicographical_compare_impl
1776  (__first1, __last1, __first2, __last2,
1777  __gnu_cxx::__ops::__iter_comp_iter(__comp));
1778  }
1779 
1780 #if __cpp_lib_three_way_comparison
1781  // Iter points to a contiguous range of unsigned narrow character type
1782  // or std::byte, suitable for comparison by memcmp.
1783  template<typename _Iter>
1784  concept __is_byte_iter = contiguous_iterator<_Iter>
1785  && __is_memcmp_ordered<iter_value_t<_Iter>>::__value;
1786 
1787  // Return a struct with two members, initialized to the smaller of x and y
1788  // (or x if they compare equal) and the result of the comparison x <=> y.
1789  template<typename _Tp>
1790  constexpr auto
1791  __min_cmp(_Tp __x, _Tp __y)
1792  {
1793  struct _Res {
1794  _Tp _M_min;
1795  decltype(__x <=> __y) _M_cmp;
1796  };
1797  auto __c = __x <=> __y;
1798  if (__c > 0)
1799  return _Res{__y, __c};
1800  return _Res{__x, __c};
1801  }
1802 
1803  /**
1804  * @brief Performs dictionary comparison on ranges.
1805  * @ingroup sorting_algorithms
1806  * @param __first1 An input iterator.
1807  * @param __last1 An input iterator.
1808  * @param __first2 An input iterator.
1809  * @param __last2 An input iterator.
1810  * @param __comp A @link comparison_functors comparison functor@endlink.
1811  * @return The comparison category that `__comp(*__first1, *__first2)`
1812  * returns.
1813  */
1814  template<typename _InputIter1, typename _InputIter2, typename _Comp>
1815  constexpr auto
1816  lexicographical_compare_three_way(_InputIter1 __first1,
1817  _InputIter1 __last1,
1818  _InputIter2 __first2,
1819  _InputIter2 __last2,
1820  _Comp __comp)
1821  -> decltype(__comp(*__first1, *__first2))
1822  {
1823  // concept requirements
1824  __glibcxx_function_requires(_InputIteratorConcept<_InputIter1>)
1825  __glibcxx_function_requires(_InputIteratorConcept<_InputIter2>)
1826  __glibcxx_requires_valid_range(__first1, __last1);
1827  __glibcxx_requires_valid_range(__first2, __last2);
1828 
1829  using _Cat = decltype(__comp(*__first1, *__first2));
1830  static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
1831 
1832  if (!std::__is_constant_evaluated())
1833  if constexpr (same_as<_Comp, __detail::_Synth3way>
1834  || same_as<_Comp, compare_three_way>)
1835  if constexpr (__is_byte_iter<_InputIter1>)
1836  if constexpr (__is_byte_iter<_InputIter2>)
1837  {
1838  const auto [__len, __lencmp] = _GLIBCXX_STD_A::
1839  __min_cmp(__last1 - __first1, __last2 - __first2);
1840  if (__len)
1841  {
1842  const auto __c
1843  = __builtin_memcmp(&*__first1, &*__first2, __len) <=> 0;
1844  if (__c != 0)
1845  return __c;
1846  }
1847  return __lencmp;
1848  }
1849 
1850  while (__first1 != __last1)
1851  {
1852  if (__first2 == __last2)
1853  return strong_ordering::greater;
1854  if (auto __cmp = __comp(*__first1, *__first2); __cmp != 0)
1855  return __cmp;
1856  ++__first1;
1857  ++__first2;
1858  }
1859  return (__first2 == __last2) <=> true; // See PR 94006
1860  }
1861 
1862  template<typename _InputIter1, typename _InputIter2>
1863  constexpr auto
1864  lexicographical_compare_three_way(_InputIter1 __first1,
1865  _InputIter1 __last1,
1866  _InputIter2 __first2,
1867  _InputIter2 __last2)
1868  {
1869  return _GLIBCXX_STD_A::
1870  lexicographical_compare_three_way(__first1, __last1, __first2, __last2,
1871  compare_three_way{});
1872  }
1873 #endif // three_way_comparison
1874 
1875  template<typename _InputIterator1, typename _InputIterator2,
1876  typename _BinaryPredicate>
1877  _GLIBCXX20_CONSTEXPR
1878  pair<_InputIterator1, _InputIterator2>
1879  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1880  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1881  {
1882  while (__first1 != __last1 && __binary_pred(__first1, __first2))
1883  {
1884  ++__first1;
1885  ++__first2;
1886  }
1887  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1888  }
1889 
1890  /**
1891  * @brief Finds the places in ranges which don't match.
1892  * @ingroup non_mutating_algorithms
1893  * @param __first1 An input iterator.
1894  * @param __last1 An input iterator.
1895  * @param __first2 An input iterator.
1896  * @return A pair of iterators pointing to the first mismatch.
1897  *
1898  * This compares the elements of two ranges using @c == and returns a pair
1899  * of iterators. The first iterator points into the first range, the
1900  * second iterator points into the second range, and the elements pointed
1901  * to by the iterators are not equal.
1902  */
1903  template<typename _InputIterator1, typename _InputIterator2>
1904  _GLIBCXX20_CONSTEXPR
1905  inline pair<_InputIterator1, _InputIterator2>
1906  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1907  _InputIterator2 __first2)
1908  {
1909  // concept requirements
1910  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1911  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1912  __glibcxx_function_requires(_EqualOpConcept<
1913  typename iterator_traits<_InputIterator1>::value_type,
1914  typename iterator_traits<_InputIterator2>::value_type>)
1915  __glibcxx_requires_valid_range(__first1, __last1);
1916 
1917  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1918  __gnu_cxx::__ops::__iter_equal_to_iter());
1919  }
1920 
1921  /**
1922  * @brief Finds the places in ranges which don't match.
1923  * @ingroup non_mutating_algorithms
1924  * @param __first1 An input iterator.
1925  * @param __last1 An input iterator.
1926  * @param __first2 An input iterator.
1927  * @param __binary_pred A binary predicate @link functors
1928  * functor@endlink.
1929  * @return A pair of iterators pointing to the first mismatch.
1930  *
1931  * This compares the elements of two ranges using the binary_pred
1932  * parameter, and returns a pair
1933  * of iterators. The first iterator points into the first range, the
1934  * second iterator points into the second range, and the elements pointed
1935  * to by the iterators are not equal.
1936  */
1937  template<typename _InputIterator1, typename _InputIterator2,
1938  typename _BinaryPredicate>
1939  _GLIBCXX20_CONSTEXPR
1940  inline pair<_InputIterator1, _InputIterator2>
1941  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1942  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1943  {
1944  // concept requirements
1945  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1946  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1947  __glibcxx_requires_valid_range(__first1, __last1);
1948 
1949  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1950  __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1951  }
1952 
1953 #if __cplusplus > 201103L
1954 
1955  template<typename _InputIterator1, typename _InputIterator2,
1956  typename _BinaryPredicate>
1957  _GLIBCXX20_CONSTEXPR
1958  pair<_InputIterator1, _InputIterator2>
1959  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1960  _InputIterator2 __first2, _InputIterator2 __last2,
1961  _BinaryPredicate __binary_pred)
1962  {
1963  while (__first1 != __last1 && __first2 != __last2
1964  && __binary_pred(__first1, __first2))
1965  {
1966  ++__first1;
1967  ++__first2;
1968  }
1969  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1970  }
1971 
1972  /**
1973  * @brief Finds the places in ranges which don't match.
1974  * @ingroup non_mutating_algorithms
1975  * @param __first1 An input iterator.
1976  * @param __last1 An input iterator.
1977  * @param __first2 An input iterator.
1978  * @param __last2 An input iterator.
1979  * @return A pair of iterators pointing to the first mismatch.
1980  *
1981  * This compares the elements of two ranges using @c == and returns a pair
1982  * of iterators. The first iterator points into the first range, the
1983  * second iterator points into the second range, and the elements pointed
1984  * to by the iterators are not equal.
1985  */
1986  template<typename _InputIterator1, typename _InputIterator2>
1987  _GLIBCXX20_CONSTEXPR
1988  inline pair<_InputIterator1, _InputIterator2>
1989  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1990  _InputIterator2 __first2, _InputIterator2 __last2)
1991  {
1992  // concept requirements
1993  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1994  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1995  __glibcxx_function_requires(_EqualOpConcept<
1996  typename iterator_traits<_InputIterator1>::value_type,
1997  typename iterator_traits<_InputIterator2>::value_type>)
1998  __glibcxx_requires_valid_range(__first1, __last1);
1999  __glibcxx_requires_valid_range(__first2, __last2);
2000 
2001  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2002  __gnu_cxx::__ops::__iter_equal_to_iter());
2003  }
2004 
2005  /**
2006  * @brief Finds the places in ranges which don't match.
2007  * @ingroup non_mutating_algorithms
2008  * @param __first1 An input iterator.
2009  * @param __last1 An input iterator.
2010  * @param __first2 An input iterator.
2011  * @param __last2 An input iterator.
2012  * @param __binary_pred A binary predicate @link functors
2013  * functor@endlink.
2014  * @return A pair of iterators pointing to the first mismatch.
2015  *
2016  * This compares the elements of two ranges using the binary_pred
2017  * parameter, and returns a pair
2018  * of iterators. The first iterator points into the first range, the
2019  * second iterator points into the second range, and the elements pointed
2020  * to by the iterators are not equal.
2021  */
2022  template<typename _InputIterator1, typename _InputIterator2,
2023  typename _BinaryPredicate>
2024  _GLIBCXX20_CONSTEXPR
2025  inline pair<_InputIterator1, _InputIterator2>
2026  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
2027  _InputIterator2 __first2, _InputIterator2 __last2,
2028  _BinaryPredicate __binary_pred)
2029  {
2030  // concept requirements
2031  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2032  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2033  __glibcxx_requires_valid_range(__first1, __last1);
2034  __glibcxx_requires_valid_range(__first2, __last2);
2035 
2036  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2037  __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
2038  }
2039 #endif
2040 
2041 _GLIBCXX_END_NAMESPACE_ALGO
2042 
2043  /// This is an overload used by find algos for the Input Iterator case.
2044  template<typename _InputIterator, typename _Predicate>
2045  _GLIBCXX20_CONSTEXPR
2046  inline _InputIterator
2047  __find_if(_InputIterator __first, _InputIterator __last,
2048  _Predicate __pred, input_iterator_tag)
2049  {
2050  while (__first != __last && !__pred(__first))
2051  ++__first;
2052  return __first;
2053  }
2054 
2055  /// This is an overload used by find algos for the RAI case.
2056  template<typename _RandomAccessIterator, typename _Predicate>
2057  _GLIBCXX20_CONSTEXPR
2058  _RandomAccessIterator
2059  __find_if(_RandomAccessIterator __first, _RandomAccessIterator __last,
2060  _Predicate __pred, random_access_iterator_tag)
2061  {
2062  typename iterator_traits<_RandomAccessIterator>::difference_type
2063  __trip_count = (__last - __first) >> 2;
2064 
2065  for (; __trip_count > 0; --__trip_count)
2066  {
2067  if (__pred(__first))
2068  return __first;
2069  ++__first;
2070 
2071  if (__pred(__first))
2072  return __first;
2073  ++__first;
2074 
2075  if (__pred(__first))
2076  return __first;
2077  ++__first;
2078 
2079  if (__pred(__first))
2080  return __first;
2081  ++__first;
2082  }
2083 
2084  switch (__last - __first)
2085  {
2086  case 3:
2087  if (__pred(__first))
2088  return __first;
2089  ++__first;
2090  // FALLTHRU
2091  case 2:
2092  if (__pred(__first))
2093  return __first;
2094  ++__first;
2095  // FALLTHRU
2096  case 1:
2097  if (__pred(__first))
2098  return __first;
2099  ++__first;
2100  // FALLTHRU
2101  case 0:
2102  default:
2103  return __last;
2104  }
2105  }
2106 
2107  template<typename _Iterator, typename _Predicate>
2108  _GLIBCXX20_CONSTEXPR
2109  inline _Iterator
2110  __find_if(_Iterator __first, _Iterator __last, _Predicate __pred)
2111  {
2112  return __find_if(__first, __last, __pred,
2113  std::__iterator_category(__first));
2114  }
2115 
2116  template<typename _InputIterator, typename _Predicate>
2117  _GLIBCXX20_CONSTEXPR
2118  typename iterator_traits<_InputIterator>::difference_type
2119  __count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
2120  {
2121  typename iterator_traits<_InputIterator>::difference_type __n = 0;
2122  for (; __first != __last; ++__first)
2123  if (__pred(__first))
2124  ++__n;
2125  return __n;
2126  }
2127 
2128  template<typename _ForwardIterator, typename _Predicate>
2129  _GLIBCXX20_CONSTEXPR
2130  _ForwardIterator
2131  __remove_if(_ForwardIterator __first, _ForwardIterator __last,
2132  _Predicate __pred)
2133  {
2134  __first = std::__find_if(__first, __last, __pred);
2135  if (__first == __last)
2136  return __first;
2137  _ForwardIterator __result = __first;
2138  ++__first;
2139  for (; __first != __last; ++__first)
2140  if (!__pred(__first))
2141  {
2142  *__result = _GLIBCXX_MOVE(*__first);
2143  ++__result;
2144  }
2145  return __result;
2146  }
2147 
2148 #if __cplusplus >= 201103L
2149  template<typename _ForwardIterator1, typename _ForwardIterator2,
2150  typename _BinaryPredicate>
2151  _GLIBCXX20_CONSTEXPR
2152  bool
2153  __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2154  _ForwardIterator2 __first2, _BinaryPredicate __pred)
2155  {
2156  // Efficiently compare identical prefixes: O(N) if sequences
2157  // have the same elements in the same order.
2158  for (; __first1 != __last1; ++__first1, (void)++__first2)
2159  if (!__pred(__first1, __first2))
2160  break;
2161 
2162  if (__first1 == __last1)
2163  return true;
2164 
2165  // Establish __last2 assuming equal ranges by iterating over the
2166  // rest of the list.
2167  _ForwardIterator2 __last2 = __first2;
2168  std::advance(__last2, std::distance(__first1, __last1));
2169  for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
2170  {
2171  if (__scan != std::__find_if(__first1, __scan,
2172  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan)))
2173  continue; // We've seen this one before.
2174 
2175  auto __matches
2176  = std::__count_if(__first2, __last2,
2177  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan));
2178  if (0 == __matches ||
2179  std::__count_if(__scan, __last1,
2180  __gnu_cxx::__ops::__iter_comp_iter(__pred, __scan))
2181  != __matches)
2182  return false;
2183  }
2184  return true;
2185  }
2186 
2187  /**
2188  * @brief Checks whether a permutation of the second sequence is equal
2189  * to the first sequence.
2190  * @ingroup non_mutating_algorithms
2191  * @param __first1 Start of first range.
2192  * @param __last1 End of first range.
2193  * @param __first2 Start of second range.
2194  * @return true if there exists a permutation of the elements in the range
2195  * [__first2, __first2 + (__last1 - __first1)), beginning with
2196  * ForwardIterator2 begin, such that equal(__first1, __last1, begin)
2197  * returns true; otherwise, returns false.
2198  */
2199  template<typename _ForwardIterator1, typename _ForwardIterator2>
2200  _GLIBCXX20_CONSTEXPR
2201  inline bool
2202  is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2203  _ForwardIterator2 __first2)
2204  {
2205  // concept requirements
2206  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
2207  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
2208  __glibcxx_function_requires(_EqualOpConcept<
2209  typename iterator_traits<_ForwardIterator1>::value_type,
2210  typename iterator_traits<_ForwardIterator2>::value_type>)
2211  __glibcxx_requires_valid_range(__first1, __last1);
2212 
2213  return std::__is_permutation(__first1, __last1, __first2,
2214  __gnu_cxx::__ops::__iter_equal_to_iter());
2215  }
2216 #endif // C++11
2217 
2218 _GLIBCXX_END_NAMESPACE_VERSION
2219 } // namespace std
2220 
2221 // NB: This file is included within many other C++ includes, as a way
2222 // of getting the base algorithms. So, make sure that parallel bits
2223 // come in too if requested.
2224 #ifdef _GLIBCXX_PARALLEL
2225 # include <parallel/algobase.h>
2226 #endif
2227 
2228 #endif
algobase.h
Parallel STL function calls corresponding to the stl_algobase.h header. The functions defined here ma...
std::is_constant_evaluated
constexpr bool is_constant_evaluated() noexcept
Returns true only when called during constant evaluation.
Definition: type_traits:3519
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:429
std::copy
constexpr _OI copy(_II __first, _II __last, _OI __result)
Copies the range [first,last) into result.
Definition: stl_algobase.h:611
std::move_backward
constexpr _BI2 move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
Moves the range [first,last) into result.
Definition: stl_algobase.h:883
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:1699
std::max
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:254
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition: stl_iterator_base_types.h:238
std
ISO C++ entities toplevel namespace is std.
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::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:2047
std::__lg
constexpr int __lg(int __n)
This is a helper function for the sort routines and for random.tcc.
Definition: stl_algobase.h:1505
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:1081
__gnu_debug::_Safe_iterator
Safe iterator wrapper.
Definition: safe_iterator.h:117
std::iterator_traits
Traits class for iterators.
Definition: stl_iterator_base_types.h:178
std::input_iterator_tag
Marking input iterators.
Definition: stl_iterator_base_types.h:93
std::output_iterator_tag
Marking output iterators.
Definition: stl_iterator_base_types.h:96
std::random_access_iterator_tag
Random-access iterators support a superset of bidirectional iterator operations.
Definition: stl_iterator_base_types.h:107