libstdc++
stl_algobase.h
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1 // Core algorithmic facilities -*- C++ -*-
2 
3 // Copyright (C) 2001-2026 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
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10 
11 // This library is distributed in the hope that it will be useful,
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15 
16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
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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,
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/cpp_type_traits.h>
61 #include <ext/type_traits.h>
62 #include <ext/numeric_traits.h>
63 #include <bits/stl_pair.h>
64 #include <bits/stl_iterator_base_types.h>
65 #include <bits/stl_iterator_base_funcs.h>
66 #include <bits/stl_iterator.h>
67 #include <bits/concept_check.h>
68 #include <debug/debug.h>
69 #include <bits/move.h> // For std::swap
70 #include <bits/predefined_ops.h>
71 #if __cplusplus >= 201103L
72 # include <type_traits>
73 #endif
74 #if __cplusplus >= 201402L
75 # include <bit> // std::__bit_width
76 #endif
77 #if __cplusplus >= 202002L
78 # include <compare>
79 # include <bits/ptr_traits.h> // std::to_address
80 #endif
81 
82 namespace std _GLIBCXX_VISIBILITY(default)
83 {
84 _GLIBCXX_BEGIN_NAMESPACE_VERSION
85 
86  /*
87  * A constexpr wrapper for __builtin_memcmp.
88  * @param __num The number of elements of type _Tp (not bytes).
89  */
90  template<typename _Tp, typename _Up>
91  _GLIBCXX14_CONSTEXPR
92  inline int
93  __memcmp(const _Tp* __first1, const _Up* __first2, size_t __num)
94  {
95 #if __cplusplus >= 201103L
96  static_assert(sizeof(_Tp) == sizeof(_Up), "can be compared with memcmp");
97 #endif
98 #ifdef __cpp_lib_is_constant_evaluated
99  if (std::is_constant_evaluated())
100  {
101  for(; __num > 0; ++__first1, ++__first2, --__num)
102  if (*__first1 != *__first2)
103  return *__first1 < *__first2 ? -1 : 1;
104  return 0;
105  }
106  else
107 #endif
108  return __builtin_memcmp(__first1, __first2, sizeof(_Tp) * __num);
109  }
110 
111 #if __cplusplus < 201103L
112  // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
113  // nutshell, we are partially implementing the resolution of DR 187,
114  // when it's safe, i.e., the value_types are equal.
115  template<bool _BoolType>
116  struct __iter_swap
117  {
118  template<typename _ForwardIterator1, typename _ForwardIterator2>
119  static void
120  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
121  {
122  typedef typename iterator_traits<_ForwardIterator1>::value_type
123  _ValueType1;
124  _ValueType1 __tmp = *__a;
125  *__a = *__b;
126  *__b = __tmp;
127  }
128  };
129 
130  template<>
131  struct __iter_swap<true>
132  {
133  template<typename _ForwardIterator1, typename _ForwardIterator2>
134  static void
135  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
136  {
137  swap(*__a, *__b);
138  }
139  };
140 #endif // C++03
141 
142  /**
143  * @brief Swaps the contents of two iterators.
144  * @ingroup mutating_algorithms
145  * @param __a An iterator.
146  * @param __b Another iterator.
147  *
148  * This function swaps the values pointed to by two iterators, not the
149  * iterators themselves.
150  */
151  template<typename _ForwardIterator1, typename _ForwardIterator2>
152  _GLIBCXX20_CONSTEXPR
153  inline void
154  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
155  {
156  // concept requirements
157  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
158  _ForwardIterator1>)
159  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
160  _ForwardIterator2>)
161 
162 #if __cplusplus < 201103L
163  typedef typename iterator_traits<_ForwardIterator1>::value_type
164  _ValueType1;
165  typedef typename iterator_traits<_ForwardIterator2>::value_type
166  _ValueType2;
167 
168  __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
169  _ValueType2>)
170  __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
171  _ValueType1>)
172 
173  typedef typename iterator_traits<_ForwardIterator1>::reference
174  _ReferenceType1;
175  typedef typename iterator_traits<_ForwardIterator2>::reference
176  _ReferenceType2;
177  std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
178  && __are_same<_ValueType1&, _ReferenceType1>::__value
179  && __are_same<_ValueType2&, _ReferenceType2>::__value>::
180  iter_swap(__a, __b);
181 #else
182  // _GLIBCXX_RESOLVE_LIB_DEFECTS
183  // 187. iter_swap underspecified
184  swap(*__a, *__b);
185 #endif
186  }
187 
188  /**
189  * @brief Swap the elements of two sequences.
190  * @ingroup mutating_algorithms
191  * @param __first1 A forward iterator.
192  * @param __last1 A forward iterator.
193  * @param __first2 A forward iterator.
194  * @return An iterator equal to @p first2+(last1-first1).
195  *
196  * Swaps each element in the range @p [first1,last1) with the
197  * corresponding element in the range @p [first2,(last1-first1)).
198  * The ranges must not overlap.
199  */
200  template<typename _ForwardIterator1, typename _ForwardIterator2>
201  _GLIBCXX20_CONSTEXPR
202  _ForwardIterator2
203  swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
204  _ForwardIterator2 __first2)
205  {
206  // concept requirements
207  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
208  _ForwardIterator1>)
209  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
210  _ForwardIterator2>)
211  __glibcxx_requires_valid_range(__first1, __last1);
212 
213  for (; __first1 != __last1; ++__first1, (void)++__first2)
214  std::iter_swap(__first1, __first2);
215  return __first2;
216  }
217 
218  /**
219  * @brief This does what you think it does.
220  * @ingroup sorting_algorithms
221  * @param __a A thing of arbitrary type.
222  * @param __b Another thing of arbitrary type.
223  * @return The lesser of the parameters.
224  *
225  * This is the simple classic generic implementation. It will work on
226  * temporary expressions, since they are only evaluated once, unlike a
227  * preprocessor macro.
228  */
229  template<typename _Tp>
230  _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
231  inline const _Tp&
232  min(const _Tp& __a, const _Tp& __b)
233  {
234  // concept requirements
235  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
236  //return __b < __a ? __b : __a;
237  if (__b < __a)
238  return __b;
239  return __a;
240  }
241 
242  /**
243  * @brief This does what you think it does.
244  * @ingroup sorting_algorithms
245  * @param __a A thing of arbitrary type.
246  * @param __b Another thing of arbitrary type.
247  * @return The greater of the parameters.
248  *
249  * This is the simple classic generic implementation. It will work on
250  * temporary expressions, since they are only evaluated once, unlike a
251  * preprocessor macro.
252  */
253  template<typename _Tp>
254  _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
255  inline const _Tp&
256  max(const _Tp& __a, const _Tp& __b)
257  {
258  // concept requirements
259  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
260  //return __a < __b ? __b : __a;
261  if (__a < __b)
262  return __b;
263  return __a;
264  }
265 
266  /**
267  * @brief This does what you think it does.
268  * @ingroup sorting_algorithms
269  * @param __a A thing of arbitrary type.
270  * @param __b Another thing of arbitrary type.
271  * @param __comp A @link comparison_functors comparison functor@endlink.
272  * @return The lesser of the parameters.
273  *
274  * This will work on temporary expressions, since they are only evaluated
275  * once, unlike a preprocessor macro.
276  */
277  template<typename _Tp, typename _Compare>
278  _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
279  inline const _Tp&
280  min(const _Tp& __a, const _Tp& __b, _Compare __comp)
281  {
282  //return __comp(__b, __a) ? __b : __a;
283  if (__comp(__b, __a))
284  return __b;
285  return __a;
286  }
287 
288  /**
289  * @brief This does what you think it does.
290  * @ingroup sorting_algorithms
291  * @param __a A thing of arbitrary type.
292  * @param __b Another thing of arbitrary type.
293  * @param __comp A @link comparison_functors comparison functor@endlink.
294  * @return The greater of the parameters.
295  *
296  * This will work on temporary expressions, since they are only evaluated
297  * once, unlike a preprocessor macro.
298  */
299  template<typename _Tp, typename _Compare>
300  _GLIBCXX_NODISCARD _GLIBCXX14_CONSTEXPR
301  inline const _Tp&
302  max(const _Tp& __a, const _Tp& __b, _Compare __comp)
303  {
304  //return __comp(__a, __b) ? __b : __a;
305  if (__comp(__a, __b))
306  return __b;
307  return __a;
308  }
309 
310 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
311 
312  template<typename _Tp, typename _Ref, typename _Ptr>
313  struct _Deque_iterator;
314 
315  struct _Bit_iterator;
316 
317 _GLIBCXX_END_NAMESPACE_CONTAINER
318 
319 #if _GLIBCXX_HOSTED
320  // Helpers for streambuf iterators (either istream or ostream).
321  // NB: avoid including <iosfwd>, relatively large.
322  template<typename _CharT>
323  struct char_traits;
324 
325  template<typename _CharT, typename _Traits>
326  class istreambuf_iterator;
327 
328  template<typename _CharT, typename _Traits>
329  class ostreambuf_iterator;
330 
331  template<bool _IsMove, typename _CharT>
332  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
333  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
334  __copy_move_a2(_CharT*, _CharT*,
335  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
336 
337  template<bool _IsMove, typename _CharT>
338  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
339  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
340  __copy_move_a2(const _CharT*, const _CharT*,
341  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
342 
343  template<bool _IsMove, typename _CharT>
344  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
345  _CharT*>::__type
346  __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
347  istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
348 
349  template<bool _IsMove, typename _CharT>
350  typename __gnu_cxx::__enable_if<
351  __is_char<_CharT>::__value,
352  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
353  __copy_move_a2(
354  istreambuf_iterator<_CharT, char_traits<_CharT> >,
355  istreambuf_iterator<_CharT, char_traits<_CharT> >,
356  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>);
357 #endif // HOSTED
358 
359 #if __cpp_lib_concepts
360  template<typename _OutIter, typename _InIter, typename _Sent = _InIter>
361  concept __memcpyable_iterators
362  = contiguous_iterator<_OutIter> && contiguous_iterator<_InIter>
363  && sized_sentinel_for<_Sent, _InIter>
364  && requires (_OutIter __o, _InIter __i) {
365  requires !!__memcpyable<decltype(std::to_address(__o)),
366  decltype(std::to_address(__i))>::__value;
367  };
368 #endif
369 
370 #if __cplusplus < 201103L
371  // Used by __copy_move_a2, __copy_n_a and __copy_move_backward_a2 to
372  // get raw pointers so that calls to __builtin_memmove will compile,
373  // because C++98 can't use 'if constexpr' so statements that use memmove
374  // with pointer arguments need to also compile for arbitrary iterator types.
375  template<typename _Iter> __attribute__((__always_inline__))
376  inline void* __ptr_or_null(_Iter) { return 0; }
377  template<typename _Tp> __attribute__((__always_inline__))
378  inline void* __ptr_or_null(_Tp* __p) { return (void*)__p; }
379 # define _GLIBCXX_TO_ADDR(P) std::__ptr_or_null(P)
380  // Used to advance output iterators (std::advance requires InputIterator).
381  template<typename _Iter> __attribute__((__always_inline__))
382  inline void __ptr_advance(_Iter&, ptrdiff_t) { }
383  template<typename _Tp> __attribute__((__always_inline__))
384  inline void __ptr_advance(_Tp*& __p, ptrdiff_t __n) { __p += __n; }
385 # define _GLIBCXX_ADVANCE(P, N) std::__ptr_advance(P, N)
386 #else
387  // For C++11 mode the __builtin_memmove calls are guarded by 'if constexpr'
388  // so we know the iterators used with memmove are guaranteed to be pointers.
389 # define _GLIBCXX_TO_ADDR(P) P
390 # define _GLIBCXX_ADVANCE(P, N) P += N
391 #endif
392 
393 #pragma GCC diagnostic push
394 #pragma GCC diagnostic ignored "-Wc++17-extensions"
395  template<bool _IsMove, typename _OutIter, typename _InIter>
396  __attribute__((__always_inline__)) _GLIBCXX20_CONSTEXPR
397  inline void
398  __assign_one(_OutIter& __out, _InIter& __in)
399  {
400 #if __cplusplus >= 201103L
401  if constexpr (_IsMove)
402  *__out = std::move(*__in);
403  else
404 #endif
405  *__out = *__in;
406  }
407 
408  template<bool _IsMove, typename _InIter, typename _Sent, typename _OutIter>
409  _GLIBCXX20_CONSTEXPR
410  inline _OutIter
411  __copy_move_a2(_InIter __first, _Sent __last, _OutIter __result)
412  {
413  typedef __decltype(*__first) _InRef;
414  typedef __decltype(*__result) _OutRef;
415  if _GLIBCXX_CONSTEXPR (!__is_trivially_assignable(_OutRef, _InRef))
416  { } /* Skip the optimizations and use the loop at the end. */
417  else if (std::__is_constant_evaluated())
418  { } /* Skip the optimizations and use the loop at the end. */
419  else if _GLIBCXX_CONSTEXPR (__memcpyable<_OutIter, _InIter>::__value)
420  {
421  ptrdiff_t __n = std::distance(__first, __last);
422  if (__builtin_expect(__n > 1, true))
423  {
424  __builtin_memmove(_GLIBCXX_TO_ADDR(__result),
425  _GLIBCXX_TO_ADDR(__first),
426  __n * sizeof(*__first));
427  _GLIBCXX_ADVANCE(__result, __n);
428  }
429  else if (__n == 1)
430  {
431  std::__assign_one<_IsMove>(__result, __first);
432  ++__result;
433  }
434  return __result;
435  }
436 #if __cpp_lib_concepts
437  else if constexpr (__memcpyable_iterators<_OutIter, _InIter, _Sent>)
438  {
439  if (auto __n = __last - __first; __n > 1) [[likely]]
440  {
441  void* __dest = std::to_address(__result);
442  const void* __src = std::to_address(__first);
443  size_t __nbytes = __n * sizeof(iter_value_t<_InIter>);
444  // Advance the iterators and convert to pointers first.
445  // This gives the iterators a chance to do bounds checking.
446  (void) std::to_address(__result += __n);
447  (void) std::to_address(__first += __n);
448  __builtin_memmove(__dest, __src, __nbytes);
449  }
450  else if (__n == 1)
451  {
452  std::__assign_one<_IsMove>(__result, __first);
453  ++__result;
454  }
455  return __result;
456  }
457 #endif
458 
459  for (; __first != __last; ++__result, (void)++__first)
460  std::__assign_one<_IsMove>(__result, __first);
461  return __result;
462  }
463 #pragma GCC diagnostic pop
464 
465  template<bool _IsMove,
466  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
467  _OI
468  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
469  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
470  _OI);
471 
472  template<bool _IsMove,
473  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
474  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
475  __copy_move_a1(_GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
476  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
477  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
478 
479  template<bool _IsMove, typename _II, typename _Tp>
480  typename __gnu_cxx::__enable_if<
481  __is_any_random_access_iter<_II>::__value,
482  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
483  __copy_move_a1(_II, _II, _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
484 
485  template<bool _IsMove, typename _II, typename _OI>
486  __attribute__((__always_inline__))
487  _GLIBCXX20_CONSTEXPR
488  inline _OI
489  __copy_move_a1(_II __first, _II __last, _OI __result)
490  { return std::__copy_move_a2<_IsMove>(__first, __last, __result); }
491 
492  template<bool _IsMove, typename _II, typename _OI>
493  __attribute__((__always_inline__))
494  _GLIBCXX20_CONSTEXPR
495  inline _OI
496  __copy_move_a(_II __first, _II __last, _OI __result)
497  {
498  return std::__niter_wrap(__result,
499  std::__copy_move_a1<_IsMove>(std::__niter_base(__first),
500  std::__niter_base(__last),
501  std::__niter_base(__result)));
502  }
503 
504  template<bool _IsMove,
505  typename _Ite, typename _Seq, typename _Cat, typename _OI>
506  _GLIBCXX20_CONSTEXPR
507  _OI
508  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
509  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
510  _OI);
511 
512  template<bool _IsMove,
513  typename _II, typename _Ite, typename _Seq, typename _Cat>
514  _GLIBCXX20_CONSTEXPR
515  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
516  __copy_move_a(_II, _II,
517  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
518 
519  template<bool _IsMove,
520  typename _IIte, typename _ISeq, typename _ICat,
521  typename _OIte, typename _OSeq, typename _OCat>
522  _GLIBCXX20_CONSTEXPR
523  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
524  __copy_move_a(const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
525  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
526  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
527 
528 #pragma GCC diagnostic push
529 #pragma GCC diagnostic ignored "-Wc++17-extensions" // for if-constexpr
530  template<typename _InputIterator, typename _Size, typename _OutputIterator>
531  _GLIBCXX20_CONSTEXPR
532  _OutputIterator
533  __copy_n_a(_InputIterator __first, _Size __n, _OutputIterator __result,
534  bool)
535  {
536  typedef __decltype(*__first) _InRef;
537  typedef __decltype(*__result) _OutRef;
538  if _GLIBCXX_CONSTEXPR (!__is_trivially_assignable(_OutRef, _InRef))
539  { } /* Skip the optimizations and use the loop at the end. */
540 #ifdef __cpp_lib_is_constant_evaluated
541  else if (std::is_constant_evaluated())
542  { } /* Skip the optimizations and use the loop at the end. */
543 #endif
544  else if _GLIBCXX_CONSTEXPR (__memcpyable<_OutputIterator,
545  _InputIterator>::__value)
546  {
547  if (__builtin_expect(__n > 1, true))
548  {
549  __builtin_memmove(_GLIBCXX_TO_ADDR(__result),
550  _GLIBCXX_TO_ADDR(__first),
551  __n * sizeof(*__first));
552  _GLIBCXX_ADVANCE(__result, __n);
553  }
554  else if (__n == 1)
555  *__result++ = *__first;
556  return __result;
557  }
558 #if __cpp_lib_concepts
559  else if constexpr (__memcpyable_iterators<_OutputIterator,
560  _InputIterator>)
561  {
562  if (__n > 1) [[likely]]
563  {
564  void* __dest = std::to_address(__result);
565  const void* __src = std::to_address(__first);
566  size_t __nbytes = __n * sizeof(iter_value_t<_InputIterator>);
567  // Advance the iterators and convert to pointers first.
568  // This gives the iterators a chance to do bounds checking.
569  (void) std::to_address(__result += __n);
570  (void) std::to_address(__first += __n);
571  __builtin_memmove(__dest, __src, __nbytes);
572  }
573  else if (__n == 1)
574  *__result++ = *__first;
575  return __result;
576  }
577 #endif
578 
579  if (__n > 0)
580  {
581  while (true)
582  {
583  *__result = *__first;
584  ++__result;
585  if (--__n > 0)
586  ++__first;
587  else
588  break;
589  }
590  }
591  return __result;
592  }
593 #pragma GCC diagnostic pop
594 
595 #if _GLIBCXX_HOSTED
596  template<typename _CharT, typename _Size>
597  typename __gnu_cxx::__enable_if<
598  __is_char<_CharT>::__value, _CharT*>::__type
599  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >,
600  _Size, _CharT*, bool);
601 
602  template<typename _CharT, typename _Size>
603  typename __gnu_cxx::__enable_if<
604  __is_char<_CharT>::__value,
605  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*> >::__type
606  __copy_n_a(istreambuf_iterator<_CharT, char_traits<_CharT> >, _Size,
607  _GLIBCXX_STD_C::_Deque_iterator<_CharT, _CharT&, _CharT*>,
608  bool);
609 #endif
610 
611  /**
612  * @brief Copies the range [first,last) into result.
613  * @ingroup mutating_algorithms
614  * @param __first An input iterator.
615  * @param __last An input iterator.
616  * @param __result An output iterator.
617  * @return result + (last - first)
618  *
619  * This inline function will boil down to a call to @c memmove whenever
620  * possible. Failing that, if random access iterators are passed, then the
621  * loop count will be known (and therefore a candidate for compiler
622  * optimizations such as unrolling). Result may not be contained within
623  * [first,last); the copy_backward function should be used instead.
624  *
625  * Note that the end of the output range is permitted to be contained
626  * within [first,last).
627  */
628  template<typename _II, typename _OI>
629  _GLIBCXX20_CONSTEXPR
630  inline _OI
631  copy(_II __first, _II __last, _OI __result)
632  {
633  // concept requirements
634  __glibcxx_function_requires(_InputIteratorConcept<_II>)
635  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
636  typename iterator_traits<_II>::reference>)
637  __glibcxx_requires_can_increment_range(__first, __last, __result);
638 
639  return std::__copy_move_a<__is_move_iterator<_II>::__value>
640  (std::__miter_base(__first), std::__miter_base(__last), __result);
641  }
642 
643 #if __cplusplus >= 201103L
644  /**
645  * @brief Moves the range [first,last) into result.
646  * @ingroup mutating_algorithms
647  * @param __first An input iterator.
648  * @param __last An input iterator.
649  * @param __result An output iterator.
650  * @return result + (last - first)
651  *
652  * This inline function will boil down to a call to @c memmove whenever
653  * possible. Failing that, if random access iterators are passed, then the
654  * loop count will be known (and therefore a candidate for compiler
655  * optimizations such as unrolling). Result may not be contained within
656  * [first,last); the move_backward function should be used instead.
657  *
658  * Note that the end of the output range is permitted to be contained
659  * within [first,last).
660  */
661  template<typename _II, typename _OI>
662  _GLIBCXX20_CONSTEXPR
663  inline _OI
664  move(_II __first, _II __last, _OI __result)
665  {
666  // concept requirements
667  __glibcxx_function_requires(_InputIteratorConcept<_II>)
668  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
669  typename iterator_traits<_II>::value_type&&>)
670  __glibcxx_requires_can_increment_range(__first, __last, __result);
671 
672  return std::__copy_move_a<true>(std::__miter_base(__first),
673  std::__miter_base(__last), __result);
674  }
675 
676 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
677 #else
678 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
679 #endif
680 
681 #pragma GCC diagnostic push
682 #pragma GCC diagnostic ignored "-Wc++17-extensions"
683  template<bool _IsMove, typename _BI1, typename _BI2>
684  _GLIBCXX20_CONSTEXPR
685  inline _BI2
686  __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
687  {
688  typedef __decltype(*__first) _InRef;
689  typedef __decltype(*__result) _OutRef;
690  if _GLIBCXX_CONSTEXPR (!__is_trivially_assignable(_OutRef, _InRef))
691  { } /* Skip the optimizations and use the loop at the end. */
692 #ifdef __cpp_lib_is_constant_evaluated
693  else if (std::is_constant_evaluated())
694  { } /* Skip the optimizations and use the loop at the end. */
695 #endif
696  else if _GLIBCXX_CONSTEXPR (__memcpyable<_BI2, _BI1>::__value)
697  {
698  ptrdiff_t __n = std::distance(__first, __last);
699  std::advance(__result, -__n);
700  if (__builtin_expect(__n > 1, true))
701  {
702  __builtin_memmove(_GLIBCXX_TO_ADDR(__result),
703  _GLIBCXX_TO_ADDR(__first),
704  __n * sizeof(*__first));
705  }
706  else if (__n == 1)
707  std::__assign_one<_IsMove>(__result, __first);
708  return __result;
709  }
710 #if __cpp_lib_concepts
711  else if constexpr (__memcpyable_iterators<_BI2, _BI1>)
712  {
713  if (auto __n = __last - __first; __n > 1) [[likely]]
714  {
715  const void* __src = std::to_address(__first);
716  // Advance the iterators and convert to pointers first.
717  // This gives the iterators a chance to do bounds checking.
718  (void) std::to_address(__result -= __n);
719  (void) std::to_address(__first += __n);
720  void* __dest = std::to_address(__result);
721  size_t __nbytes = __n * sizeof(iter_value_t<_BI1>);
722  __builtin_memmove(__dest, __src, __nbytes);
723  }
724  else if (__n == 1)
725  {
726  --__result;
727  std::__assign_one<_IsMove>(__result, __first);
728  }
729  return __result;
730  }
731 #endif
732 
733  while (__first != __last)
734  {
735  --__last;
736  --__result;
737  std::__assign_one<_IsMove>(__result, __last);
738  }
739  return __result;
740  }
741 #pragma GCC diagnostic pop
742 
743 #undef _GLIBCXX_TO_ADDR
744 #undef _GLIBCXX_ADVANCE
745 
746  template<bool _IsMove, typename _BI1, typename _BI2>
747  __attribute__((__always_inline__))
748  _GLIBCXX20_CONSTEXPR
749  inline _BI2
750  __copy_move_backward_a1(_BI1 __first, _BI1 __last, _BI2 __result)
751  { return std::__copy_move_backward_a2<_IsMove>(__first, __last, __result); }
752 
753  template<bool _IsMove,
754  typename _Tp, typename _Ref, typename _Ptr, typename _OI>
755  _OI
756  __copy_move_backward_a1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
757  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
758  _OI);
759 
760  template<bool _IsMove,
761  typename _ITp, typename _IRef, typename _IPtr, typename _OTp>
762  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>
763  __copy_move_backward_a1(
764  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
765  _GLIBCXX_STD_C::_Deque_iterator<_ITp, _IRef, _IPtr>,
766  _GLIBCXX_STD_C::_Deque_iterator<_OTp, _OTp&, _OTp*>);
767 
768  template<bool _IsMove, typename _II, typename _Tp>
769  typename __gnu_cxx::__enable_if<
770  __is_any_random_access_iter<_II>::__value,
771  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*> >::__type
772  __copy_move_backward_a1(_II, _II,
773  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>);
774 
775  template<bool _IsMove, typename _II, typename _OI>
776  __attribute__((__always_inline__))
777  _GLIBCXX20_CONSTEXPR
778  inline _OI
779  __copy_move_backward_a(_II __first, _II __last, _OI __result)
780  {
781  return std::__niter_wrap(__result,
782  std::__copy_move_backward_a1<_IsMove>
783  (std::__niter_base(__first), std::__niter_base(__last),
784  std::__niter_base(__result)));
785  }
786 
787  template<bool _IsMove,
788  typename _Ite, typename _Seq, typename _Cat, typename _OI>
789  _GLIBCXX20_CONSTEXPR
790  _OI
791  __copy_move_backward_a(
792  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
793  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
794  _OI);
795 
796  template<bool _IsMove,
797  typename _II, typename _Ite, typename _Seq, typename _Cat>
798  _GLIBCXX20_CONSTEXPR
799  __gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
800  __copy_move_backward_a(_II, _II,
801  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&);
802 
803  template<bool _IsMove,
804  typename _IIte, typename _ISeq, typename _ICat,
805  typename _OIte, typename _OSeq, typename _OCat>
806  _GLIBCXX20_CONSTEXPR
807  ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>
808  __copy_move_backward_a(
809  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
810  const ::__gnu_debug::_Safe_iterator<_IIte, _ISeq, _ICat>&,
811  const ::__gnu_debug::_Safe_iterator<_OIte, _OSeq, _OCat>&);
812 
813  /**
814  * @brief Copies the range [first,last) into result.
815  * @ingroup mutating_algorithms
816  * @param __first A bidirectional iterator.
817  * @param __last A bidirectional iterator.
818  * @param __result A bidirectional iterator.
819  * @return result - (last - first)
820  *
821  * The function has the same effect as copy, but starts at the end of the
822  * range and works its way to the start, returning the start of the result.
823  * This inline function will boil down to a call to @c memmove whenever
824  * possible. Failing that, if random access iterators are passed, then the
825  * loop count will be known (and therefore a candidate for compiler
826  * optimizations such as unrolling).
827  *
828  * Result may not be in the range (first,last]. Use copy instead. Note
829  * that the start of the output range may overlap [first,last).
830  */
831  template<typename _BI1, typename _BI2>
832  __attribute__((__always_inline__))
833  _GLIBCXX20_CONSTEXPR
834  inline _BI2
835  copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
836  {
837  // concept requirements
838  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
839  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
840  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
841  typename iterator_traits<_BI1>::reference>)
842  __glibcxx_requires_can_decrement_range(__first, __last, __result);
843 
844  return std::__copy_move_backward_a<__is_move_iterator<_BI1>::__value>
845  (std::__miter_base(__first), std::__miter_base(__last), __result);
846  }
847 
848 #if __cplusplus >= 201103L
849  /**
850  * @brief Moves the range [first,last) into result.
851  * @ingroup mutating_algorithms
852  * @param __first A bidirectional iterator.
853  * @param __last A bidirectional iterator.
854  * @param __result A bidirectional iterator.
855  * @return result - (last - first)
856  *
857  * The function has the same effect as move, but starts at the end of the
858  * range and works its way to the start, returning the start of the result.
859  * This inline function will boil down to a call to @c memmove whenever
860  * possible. Failing that, if random access iterators are passed, then the
861  * loop count will be known (and therefore a candidate for compiler
862  * optimizations such as unrolling).
863  *
864  * Result may not be in the range (first,last]. Use move instead. Note
865  * that the start of the output range may overlap [first,last).
866  */
867  template<typename _BI1, typename _BI2>
868  __attribute__((__always_inline__))
869  _GLIBCXX20_CONSTEXPR
870  inline _BI2
871  move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
872  {
873  // concept requirements
874  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
875  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
876  __glibcxx_function_requires(_OutputIteratorConcept<_BI2,
877  typename iterator_traits<_BI1>::value_type&&>)
878  __glibcxx_requires_can_decrement_range(__first, __last, __result);
879 
880  return std::__copy_move_backward_a<true>(std::__miter_base(__first),
881  std::__miter_base(__last),
882  __result);
883  }
884 
885 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
886 #else
887 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
888 #endif
889 
890 #pragma GCC diagnostic push
891 #pragma GCC diagnostic ignored "-Wc++17-extensions"
892  template<typename _ForwardIterator, typename _Tp>
893  _GLIBCXX20_CONSTEXPR
894  inline void
895  __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
896  const _Tp& __value)
897  {
898 #pragma GCC diagnostic push
899 #pragma GCC diagnostic ignored "-Wlong-long"
900  // We can optimize this loop by moving the load from __value outside
901  // the loop, but only if we know that making that copy is trivial,
902  // and the assignment in the loop is also trivial (so that the identity
903  // of the operand doesn't matter).
904  const bool __load_outside_loop =
905 #if __has_builtin(__is_trivially_constructible) \
906  && __has_builtin(__is_trivially_assignable)
907  __is_trivially_constructible(_Tp, const _Tp&)
908  && __is_trivially_assignable(__decltype(*__first), const _Tp&)
909 #else
910  __is_trivially_copyable(_Tp)
911  && __is_same(_Tp, __typeof__(*__first))
912 #endif
913  && sizeof(_Tp) <= sizeof(long long);
914 #pragma GCC diagnostic pop
915 
916  // When the condition is true, we use a copy of __value,
917  // otherwise we just use another reference.
918  typedef typename __gnu_cxx::__conditional_type<__load_outside_loop,
919  const _Tp,
920  const _Tp&>::__type _Up;
921  _Up __val(__value);
922  for (; __first != __last; ++__first)
923  *__first = __val;
924  }
925 #pragma GCC diagnostic pop
926 
927  // Specialization: for char types we can use memset.
928  template<typename _Up, typename _Tp>
929  _GLIBCXX20_CONSTEXPR
930  inline typename
931  __gnu_cxx::__enable_if<__is_byte<_Up>::__value
932  && (__are_same<_Up, _Tp>::__value // for std::byte
933  || __memcpyable_integer<_Tp>::__width),
934  void>::__type
935  __fill_a1(_Up* __first, _Up* __last, const _Tp& __x)
936  {
937  // This hoists the load out of the loop and also ensures that we don't
938  // use memset for cases where the assignment would be ill-formed.
939  const _Up __val = __x;
940 #if __cpp_lib_is_constant_evaluated
941  if (std::is_constant_evaluated())
942  {
943  for (; __first != __last; ++__first)
944  *__first = __val;
945  return;
946  }
947 #endif
948  if (const size_t __len = __last - __first)
949  __builtin_memset(__first, static_cast<unsigned char>(__val), __len);
950  }
951 
952  template<typename _Ite, typename _Cont, typename _Tp>
953  __attribute__((__always_inline__))
954  _GLIBCXX20_CONSTEXPR
955  inline void
956  __fill_a1(::__gnu_cxx::__normal_iterator<_Ite, _Cont> __first,
957  ::__gnu_cxx::__normal_iterator<_Ite, _Cont> __last,
958  const _Tp& __value)
959  { std::__fill_a1(__first.base(), __last.base(), __value); }
960 
961  template<typename _Tp, typename _VTp>
962  void
963  __fill_a1(const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
964  const _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Tp&, _Tp*>&,
965  const _VTp&);
966 
967  _GLIBCXX20_CONSTEXPR
968  void
969  __fill_a1(_GLIBCXX_STD_C::_Bit_iterator, _GLIBCXX_STD_C::_Bit_iterator,
970  const bool&);
971 
972  template<typename _FIte, typename _Tp>
973  __attribute__((__always_inline__))
974  _GLIBCXX20_CONSTEXPR
975  inline void
976  __fill_a(_FIte __first, _FIte __last, const _Tp& __value)
977  { std::__fill_a1(__first, __last, __value); }
978 
979  template<typename _Ite, typename _Seq, typename _Cat, typename _Tp>
980  _GLIBCXX20_CONSTEXPR
981  void
982  __fill_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
983  const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>&,
984  const _Tp&);
985 
986  /**
987  * @brief Fills the range [first,last) with copies of value.
988  * @ingroup mutating_algorithms
989  * @param __first A forward iterator.
990  * @param __last A forward iterator.
991  * @param __value A reference-to-const of arbitrary type.
992  *
993  * This function fills a range with copies of the same value. For char
994  * types filling contiguous areas of memory, this becomes an inline call
995  * to @c memset or @c wmemset.
996  */
997  template<typename _ForwardIterator, typename _Tp>
998  __attribute__((__always_inline__))
999  _GLIBCXX20_CONSTEXPR
1000  inline void
1001  fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
1002  {
1003  // concept requirements
1004  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
1005  _ForwardIterator>)
1006  __glibcxx_requires_valid_range(__first, __last);
1007 
1008  std::__fill_a(__first, __last, __value);
1009  }
1010 
1011 #pragma GCC diagnostic push
1012 #pragma GCC diagnostic ignored "-Wlong-long"
1013  // Used by fill_n, generate_n, etc. to convert _Size to an integral type:
1014  inline _GLIBCXX_CONSTEXPR int
1015  __size_to_integer(int __n) { return __n; }
1016  inline _GLIBCXX_CONSTEXPR unsigned
1017  __size_to_integer(unsigned __n) { return __n; }
1018  inline _GLIBCXX_CONSTEXPR long
1019  __size_to_integer(long __n) { return __n; }
1020  inline _GLIBCXX_CONSTEXPR unsigned long
1021  __size_to_integer(unsigned long __n) { return __n; }
1022  inline _GLIBCXX_CONSTEXPR long long
1023  __size_to_integer(long long __n) { return __n; }
1024  inline _GLIBCXX_CONSTEXPR unsigned long long
1025  __size_to_integer(unsigned long long __n) { return __n; }
1026 
1027 #if defined(__GLIBCXX_TYPE_INT_N_0)
1028  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_0
1029  __size_to_integer(__GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1030  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_0
1031  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_0 __n) { return __n; }
1032 #endif
1033 #if defined(__GLIBCXX_TYPE_INT_N_1)
1034  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_1
1035  __size_to_integer(__GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1036  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_1
1037  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_1 __n) { return __n; }
1038 #endif
1039 #if defined(__GLIBCXX_TYPE_INT_N_2)
1040  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_2
1041  __size_to_integer(__GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1042  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_2
1043  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_2 __n) { return __n; }
1044 #endif
1045 #if defined(__GLIBCXX_TYPE_INT_N_3)
1046  __extension__ inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_3
1047  __size_to_integer(__GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1048  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __GLIBCXX_TYPE_INT_N_3
1049  __size_to_integer(unsigned __GLIBCXX_TYPE_INT_N_3 __n) { return __n; }
1050 #endif
1051 
1052 #if defined(__STRICT_ANSI__) && defined(__SIZEOF_INT128__)
1053  __extension__ inline _GLIBCXX_CONSTEXPR __int128
1054  __size_to_integer(__int128 __n) { return __n; }
1055  __extension__ inline _GLIBCXX_CONSTEXPR unsigned __int128
1056  __size_to_integer(unsigned __int128 __n) { return __n; }
1057 #endif
1058 
1059  inline _GLIBCXX_CONSTEXPR long long
1060  __size_to_integer(float __n) { return (long long)__n; }
1061  inline _GLIBCXX_CONSTEXPR long long
1062  __size_to_integer(double __n) { return (long long)__n; }
1063  inline _GLIBCXX_CONSTEXPR long long
1064  __size_to_integer(long double __n) { return (long long)__n; }
1065 #ifdef _GLIBCXX_USE_FLOAT128
1066  __extension__ inline _GLIBCXX_CONSTEXPR long long
1067  __size_to_integer(__float128 __n) { return (long long)__n; }
1068 #endif
1069 #pragma GCC diagnostic pop
1070 
1071 #pragma GCC diagnostic push
1072 #pragma GCC diagnostic ignored "-Wc++17-extensions"
1073 #pragma GCC diagnostic ignored "-Wlong-long"
1074  template<typename _OutputIterator, typename _Size, typename _Tp>
1075  _GLIBCXX20_CONSTEXPR
1076  inline _OutputIterator
1077  __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
1078  {
1079  // See std::__fill_a1 for explanation of this condition.
1080  const bool __load_outside_loop =
1081 #if __has_builtin(__is_trivially_constructible) \
1082  && __has_builtin(__is_trivially_assignable)
1083  __is_trivially_constructible(_Tp, const _Tp&)
1084  && __is_trivially_assignable(__decltype(*__first), const _Tp&)
1085 #else
1086  __is_trivially_copyable(_Tp)
1087  && __is_same(_Tp, __typeof__(*__first))
1088 #endif
1089  && sizeof(_Tp) <= sizeof(long long);
1090 
1091  // When the condition is true, we use a copy of __value,
1092  // otherwise we just use another reference.
1093  typedef typename __gnu_cxx::__conditional_type<__load_outside_loop,
1094  const _Tp,
1095  const _Tp&>::__type _Up;
1096  _Up __val(__value);
1097  for (; __n > 0; --__n, (void) ++__first)
1098  *__first = __val;
1099  return __first;
1100  }
1101 #pragma GCC diagnostic pop
1102 
1103  template<typename _Ite, typename _Seq, typename _Cat, typename _Size,
1104  typename _Tp>
1105  _GLIBCXX20_CONSTEXPR
1106  ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>
1107  __fill_n_a(const ::__gnu_debug::_Safe_iterator<_Ite, _Seq, _Cat>& __first,
1108  _Size __n, const _Tp& __value,
1109  std::input_iterator_tag);
1110 
1111  template<typename _OutputIterator, typename _Size, typename _Tp>
1112  __attribute__((__always_inline__))
1113  _GLIBCXX20_CONSTEXPR
1114  inline _OutputIterator
1115  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1116  std::output_iterator_tag)
1117  {
1118 #if __cplusplus >= 201103L
1119  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1120 #endif
1121  return __fill_n_a1(__first, __n, __value);
1122  }
1123 
1124  template<typename _OutputIterator, typename _Size, typename _Tp>
1125  __attribute__((__always_inline__))
1126  _GLIBCXX20_CONSTEXPR
1127  inline _OutputIterator
1128  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1129  std::input_iterator_tag)
1130  {
1131 #if __cplusplus >= 201103L
1132  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1133 #endif
1134  return __fill_n_a1(__first, __n, __value);
1135  }
1136 
1137  template<typename _OutputIterator, typename _Size, typename _Tp>
1138  __attribute__((__always_inline__))
1139  _GLIBCXX20_CONSTEXPR
1140  inline _OutputIterator
1141  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value,
1142  std::random_access_iterator_tag)
1143  {
1144 #if __cplusplus >= 201103L
1145  static_assert(is_integral<_Size>{}, "fill_n must pass integral size");
1146 #endif
1147  if (__n <= 0)
1148  return __first;
1149 
1150  typename iterator_traits<_OutputIterator>::difference_type __d = __n;
1151  __glibcxx_requires_can_increment(__first, __d);
1152 
1153  _OutputIterator __last = __first + __d;
1154  std::__fill_a(__first, __last, __value);
1155  return __last;
1156  }
1157 
1158  /**
1159  * @brief Fills the range [first,first+n) with copies of value.
1160  * @ingroup mutating_algorithms
1161  * @param __first An output iterator.
1162  * @param __n The count of copies to perform.
1163  * @param __value A reference-to-const of arbitrary type.
1164  * @return The iterator at first+n.
1165  *
1166  * This function fills a range with copies of the same value. For char
1167  * types filling contiguous areas of memory, this becomes an inline call
1168  * to @c memset or @c wmemset.
1169  *
1170  * If @p __n is negative, the function does nothing.
1171  */
1172  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1173  // DR 865. More algorithms that throw away information
1174  // DR 426. search_n(), fill_n(), and generate_n() with negative n
1175  template<typename _OI, typename _Size, typename _Tp>
1176  __attribute__((__always_inline__))
1177  _GLIBCXX20_CONSTEXPR
1178  inline _OI
1179  fill_n(_OI __first, _Size __n, const _Tp& __value)
1180  {
1181  // concept requirements
1182  __glibcxx_function_requires(_OutputIteratorConcept<_OI, const _Tp&>)
1183 
1184  return std::__fill_n_a(__first, std::__size_to_integer(__n), __value,
1185  std::__iterator_category(__first));
1186  }
1187 
1188  template<bool _BoolType>
1189  struct __equal
1190  {
1191  template<typename _II1, typename _II2>
1192  _GLIBCXX20_CONSTEXPR
1193  static bool
1194  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1195  {
1196  for (; __first1 != __last1; ++__first1, (void) ++__first2)
1197  if (!(*__first1 == *__first2))
1198  return false;
1199  return true;
1200  }
1201  };
1202 
1203  template<>
1204  struct __equal<true>
1205  {
1206  template<typename _Tp>
1207  _GLIBCXX20_CONSTEXPR
1208  static bool
1209  equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
1210  {
1211  if (const size_t __len = (__last1 - __first1))
1212  return !std::__memcmp(__first1, __first2, __len);
1213  return true;
1214  }
1215  };
1216 
1217  template<typename _Tp, typename _Ref, typename _Ptr, typename _II>
1218  typename __gnu_cxx::__enable_if<
1219  __is_any_random_access_iter<_II>::__value, bool>::__type
1220  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1221  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>,
1222  _II);
1223 
1224  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1225  typename _Tp2, typename _Ref2, typename _Ptr2>
1226  bool
1227  __equal_aux1(_GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1228  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1229  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1230 
1231  template<typename _II, typename _Tp, typename _Ref, typename _Ptr>
1232  typename __gnu_cxx::__enable_if<
1233  __is_any_random_access_iter<_II>::__value, bool>::__type
1234  __equal_aux1(_II, _II,
1235  _GLIBCXX_STD_C::_Deque_iterator<_Tp, _Ref, _Ptr>);
1236 
1237  template<typename _II1, typename _II2>
1238  _GLIBCXX20_CONSTEXPR
1239  inline bool
1240  __equal_aux1(_II1 __first1, _II1 __last1, _II2 __first2)
1241  {
1242  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1243  const bool __simple = ((__is_integer<_ValueType1>::__value
1244 #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer)
1245  || __is_pointer(_ValueType1)
1246 #endif
1247 #if __glibcxx_byte && __glibcxx_type_trait_variable_templates
1248  // bits/cpp_type_traits.h declares std::byte
1249  || is_same_v<_ValueType1, byte>
1250 #endif
1251  ) && __memcmpable<_II1, _II2>::__value);
1252  return std::__equal<__simple>::equal(__first1, __last1, __first2);
1253  }
1254 
1255  template<typename _II1, typename _II2>
1256  __attribute__((__always_inline__))
1257  _GLIBCXX20_CONSTEXPR
1258  inline bool
1259  __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
1260  {
1261  return std::__equal_aux1(std::__niter_base(__first1),
1262  std::__niter_base(__last1),
1263  std::__niter_base(__first2));
1264  }
1265 
1266  template<typename _II1, typename _Seq1, typename _Cat1, typename _II2>
1267  _GLIBCXX20_CONSTEXPR
1268  bool
1269  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1270  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1271  _II2);
1272 
1273  template<typename _II1, typename _II2, typename _Seq2, typename _Cat2>
1274  _GLIBCXX20_CONSTEXPR
1275  bool
1276  __equal_aux(_II1, _II1,
1277  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1278 
1279  template<typename _II1, typename _Seq1, typename _Cat1,
1280  typename _II2, typename _Seq2, typename _Cat2>
1281  _GLIBCXX20_CONSTEXPR
1282  bool
1283  __equal_aux(const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1284  const ::__gnu_debug::_Safe_iterator<_II1, _Seq1, _Cat1>&,
1285  const ::__gnu_debug::_Safe_iterator<_II2, _Seq2, _Cat2>&);
1286 
1287  template<typename, typename>
1288  struct __lc_rai
1289  {
1290  template<typename _II1, typename _II2>
1291  _GLIBCXX20_CONSTEXPR
1292  static _II1
1293  __newlast1(_II1, _II1 __last1, _II2, _II2)
1294  { return __last1; }
1295 
1296  template<typename _II>
1297  _GLIBCXX20_CONSTEXPR
1298  static bool
1299  __cnd2(_II __first, _II __last)
1300  { return __first != __last; }
1301  };
1302 
1303  template<>
1304  struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
1305  {
1306  template<typename _RAI1, typename _RAI2>
1307  _GLIBCXX20_CONSTEXPR
1308  static _RAI1
1309  __newlast1(_RAI1 __first1, _RAI1 __last1,
1310  _RAI2 __first2, _RAI2 __last2)
1311  {
1312  typedef typename iterator_traits<_RAI1>::difference_type _Diff1;
1313  typedef typename iterator_traits<_RAI2>::difference_type _Diff2;
1314  const _Diff1 __diff1 = __last1 - __first1;
1315  const _Diff2 __diff2 = __last2 - __first2;
1316  return __diff2 < __diff1 ? __first1 + _Diff1(__diff2) : __last1;
1317  }
1318 
1319  template<typename _RAI>
1320  static _GLIBCXX20_CONSTEXPR bool
1321  __cnd2(_RAI, _RAI)
1322  { return true; }
1323  };
1324 
1325  template<typename _II1, typename _II2, typename _Compare>
1326  _GLIBCXX20_CONSTEXPR
1327  bool
1328  __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
1329  _II2 __first2, _II2 __last2,
1330  _Compare __comp)
1331  {
1332  typedef __decltype(std::__iter_concept_or_category<_II1>()) _Category1;
1333  typedef __decltype(std::__iter_concept_or_category<_II2>()) _Category2;
1334  typedef std::__lc_rai<_Category1, _Category2> __rai_type;
1335 
1336  __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1337  for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1338  ++__first1, (void)++__first2)
1339  {
1340  if (__comp(*__first1, *__first2))
1341  return true;
1342  if (__comp(*__first2, *__first1))
1343  return false;
1344  }
1345  return __first1 == __last1 && __first2 != __last2;
1346  }
1347 
1348  template<bool _BoolType>
1349  struct __lexicographical_compare
1350  {
1351  template<typename _II1, typename _II2>
1352  _GLIBCXX20_CONSTEXPR
1353  static bool
1354  __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1355  {
1356  using __gnu_cxx::__ops::less;
1357  return std::__lexicographical_compare_impl(__first1, __last1,
1358  __first2, __last2,
1359  less());
1360  }
1361 
1362  template<typename _II1, typename _II2>
1363  _GLIBCXX20_CONSTEXPR
1364  static int
1365  __3way(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1366  {
1367  while (__first1 != __last1)
1368  {
1369  if (__first2 == __last2)
1370  return +1;
1371  if (*__first1 < *__first2)
1372  return -1;
1373  if (*__first2 < *__first1)
1374  return +1;
1375  ++__first1;
1376  ++__first2;
1377  }
1378  return int(__first2 == __last2) - 1;
1379  }
1380  };
1381 
1382  template<>
1383  struct __lexicographical_compare<true>
1384  {
1385  template<typename _Tp, typename _Up>
1386  _GLIBCXX20_CONSTEXPR
1387  static bool
1388  __lc(const _Tp* __first1, const _Tp* __last1,
1389  const _Up* __first2, const _Up* __last2)
1390  { return __3way(__first1, __last1, __first2, __last2) < 0; }
1391 
1392  template<typename _Tp, typename _Up>
1393  _GLIBCXX20_CONSTEXPR
1394  static ptrdiff_t
1395  __3way(const _Tp* __first1, const _Tp* __last1,
1396  const _Up* __first2, const _Up* __last2)
1397  {
1398  const size_t __len1 = __last1 - __first1;
1399  const size_t __len2 = __last2 - __first2;
1400  if (const size_t __len = std::min(__len1, __len2))
1401  if (int __result = std::__memcmp(__first1, __first2, __len))
1402  return __result;
1403  return ptrdiff_t(__len1 - __len2);
1404  }
1405  };
1406 
1407  template<typename _II1, typename _II2>
1408  _GLIBCXX20_CONSTEXPR
1409  inline bool
1410  __lexicographical_compare_aux1(_II1 __first1, _II1 __last1,
1411  _II2 __first2, _II2 __last2)
1412  {
1413  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1414  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1415 #if _GLIBCXX_USE_BUILTIN_TRAIT(__is_pointer)
1416  const bool __simple =
1417  (__is_memcmp_ordered_with<_ValueType1, _ValueType2>::__value
1418  && __is_pointer(_II1) && __is_pointer(_II2)
1419 #if __cplusplus > 201703L && __glibcxx_concepts
1420  // For C++20 iterator_traits<volatile T*>::value_type is non-volatile
1421  // so __is_byte<T> could be true, but we can't use memcmp with
1422  // volatile data.
1423  && !is_volatile_v<remove_reference_t<iter_reference_t<_II1>>>
1424  && !is_volatile_v<remove_reference_t<iter_reference_t<_II2>>>
1425 #endif
1426  );
1427 #else
1428  const bool __simple = false;
1429 #endif
1430 
1431  return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
1432  __first2, __last2);
1433  }
1434 
1435  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1436  typename _Tp2>
1437  bool
1438  __lexicographical_compare_aux1(
1439  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1440  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1441  _Tp2*, _Tp2*);
1442 
1443  template<typename _Tp1,
1444  typename _Tp2, typename _Ref2, typename _Ptr2>
1445  bool
1446  __lexicographical_compare_aux1(_Tp1*, _Tp1*,
1447  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1448  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1449 
1450  template<typename _Tp1, typename _Ref1, typename _Ptr1,
1451  typename _Tp2, typename _Ref2, typename _Ptr2>
1452  bool
1453  __lexicographical_compare_aux1(
1454  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1455  _GLIBCXX_STD_C::_Deque_iterator<_Tp1, _Ref1, _Ptr1>,
1456  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>,
1457  _GLIBCXX_STD_C::_Deque_iterator<_Tp2, _Ref2, _Ptr2>);
1458 
1459  template<typename _II1, typename _II2>
1460  _GLIBCXX20_CONSTEXPR
1461  inline bool
1462  __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
1463  _II2 __first2, _II2 __last2)
1464  {
1465  return std::__lexicographical_compare_aux1(std::__niter_base(__first1),
1466  std::__niter_base(__last1),
1467  std::__niter_base(__first2),
1468  std::__niter_base(__last2));
1469  }
1470 
1471  template<typename _Iter1, typename _Seq1, typename _Cat1,
1472  typename _II2>
1473  _GLIBCXX20_CONSTEXPR
1474  bool
1475  __lexicographical_compare_aux(
1476  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1477  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1478  _II2, _II2);
1479 
1480  template<typename _II1,
1481  typename _Iter2, typename _Seq2, typename _Cat2>
1482  _GLIBCXX20_CONSTEXPR
1483  bool
1484  __lexicographical_compare_aux(
1485  _II1, _II1,
1486  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1487  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1488 
1489  template<typename _Iter1, typename _Seq1, typename _Cat1,
1490  typename _Iter2, typename _Seq2, typename _Cat2>
1491  _GLIBCXX20_CONSTEXPR
1492  bool
1493  __lexicographical_compare_aux(
1494  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1495  const ::__gnu_debug::_Safe_iterator<_Iter1, _Seq1, _Cat1>&,
1496  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&,
1497  const ::__gnu_debug::_Safe_iterator<_Iter2, _Seq2, _Cat2>&);
1498 
1499  template<typename _ForwardIterator, typename _Tp, typename _Compare>
1500  _GLIBCXX20_CONSTEXPR
1501  _ForwardIterator
1502  __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1503  const _Tp& __val, _Compare __comp)
1504  {
1505  typedef typename iterator_traits<_ForwardIterator>::difference_type
1506  _DistanceType;
1507 
1508  _DistanceType __len = std::distance(__first, __last);
1509 
1510  while (__len > 0)
1511  {
1512  _DistanceType __half = __len >> 1;
1513  _ForwardIterator __middle = __first;
1514  std::advance(__middle, __half);
1515  if (__comp(*__middle, __val))
1516  {
1517  __first = __middle;
1518  ++__first;
1519  __len = __len - __half - 1;
1520  }
1521  else
1522  __len = __half;
1523  }
1524  return __first;
1525  }
1526 
1527  /**
1528  * @brief Finds the first position in which @a val could be inserted
1529  * without changing the ordering.
1530  * @param __first An iterator.
1531  * @param __last Another iterator.
1532  * @param __val The search term.
1533  * @return An iterator pointing to the first element <em>not less
1534  * than</em> @a val, or end() if every element is less than
1535  * @a val.
1536  * @ingroup binary_search_algorithms
1537  */
1538  template<typename _ForwardIterator, typename _Tp>
1539  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1540  inline _ForwardIterator
1541  lower_bound(_ForwardIterator __first, _ForwardIterator __last,
1542  const _Tp& __val)
1543  {
1544  // concept requirements
1545  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
1546  __glibcxx_function_requires(_LessThanOpConcept<
1547  typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
1548  __glibcxx_requires_partitioned_lower(__first, __last, __val);
1549 
1550  return std::__lower_bound(__first, __last, __val,
1551  __gnu_cxx::__ops::less());
1552  }
1553 
1554  /// This is a helper function for the sort routines and for random.tcc.
1555  // Precondition: __n > 0.
1556  template<typename _Tp>
1557  inline _GLIBCXX_CONSTEXPR _Tp
1558  __lg(_Tp __n)
1559  {
1560 #if __cplusplus >= 201402L
1561  return std::__bit_width(make_unsigned_t<_Tp>(__n)) - 1;
1562 #else
1563 #pragma GCC diagnostic push
1564 #pragma GCC diagnostic ignored "-Wlong-long"
1565  // Use +__n so it promotes to at least int.
1566  return (sizeof(+__n) * __CHAR_BIT__ - 1)
1567  - (sizeof(+__n) == sizeof(long long)
1568  ? __builtin_clzll(+__n)
1569  : (sizeof(+__n) == sizeof(long)
1570  ? __builtin_clzl(+__n)
1571  : __builtin_clz(+__n)));
1572 #pragma GCC diagnostic pop
1573 #endif
1574  }
1575 
1576 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1577 
1578  /**
1579  * @brief Tests a range for element-wise equality.
1580  * @ingroup non_mutating_algorithms
1581  * @param __first1 An input iterator.
1582  * @param __last1 An input iterator.
1583  * @param __first2 An input iterator.
1584  * @return A boolean true or false.
1585  *
1586  * This compares the elements of two ranges using @c == and returns true or
1587  * false depending on whether all of the corresponding elements of the
1588  * ranges are equal.
1589  */
1590  template<typename _II1, typename _II2>
1591  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1592  inline bool
1593  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1594  {
1595  // concept requirements
1596  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1597  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1598  __glibcxx_function_requires(_EqualOpConcept<
1599  typename iterator_traits<_II1>::value_type,
1600  typename iterator_traits<_II2>::value_type>)
1601  __glibcxx_requires_can_increment_range(__first1, __last1, __first2);
1602 
1603  return std::__equal_aux(__first1, __last1, __first2);
1604  }
1605 
1606  /**
1607  * @brief Tests a range for element-wise equality.
1608  * @ingroup non_mutating_algorithms
1609  * @param __first1 An input iterator.
1610  * @param __last1 An input iterator.
1611  * @param __first2 An input iterator.
1612  * @param __binary_pred A binary predicate @link functors
1613  * functor@endlink.
1614  * @return A boolean true or false.
1615  *
1616  * This compares the elements of two ranges using the binary_pred
1617  * parameter, and returns true or
1618  * false depending on whether all of the corresponding elements of the
1619  * ranges are equal.
1620  */
1621  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1622  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1623  inline bool
1624  equal(_IIter1 __first1, _IIter1 __last1,
1625  _IIter2 __first2, _BinaryPredicate __binary_pred)
1626  {
1627  // concept requirements
1628  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1629  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1630  __glibcxx_requires_valid_range(__first1, __last1);
1631 
1632  for (; __first1 != __last1; ++__first1, (void)++__first2)
1633  if (!bool(__binary_pred(*__first1, *__first2)))
1634  return false;
1635  return true;
1636  }
1637 
1638 #if __cplusplus >= 201103L
1639 #pragma GCC diagnostic push
1640 #pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
1641 
1642  // 4-iterator version of std::equal<It1, It2> for use in C++11.
1643  template<typename _II1, typename _II2>
1644  _GLIBCXX20_CONSTEXPR
1645  inline bool
1646  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1647  {
1648  using _RATag = random_access_iterator_tag;
1649  using _Cat1 = decltype(std::__iter_concept_or_category<_II1>());
1650  using _Cat2 = decltype(std::__iter_concept_or_category<_II2>());
1651  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1652  if constexpr (_RAIters::value)
1653  {
1654  if ((__last1 - __first1) != (__last2 - __first2))
1655  return false;
1656  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1657  }
1658  else
1659  {
1660  for (; __first1 != __last1 && __first2 != __last2;
1661  ++__first1, (void)++__first2)
1662  if (!(*__first1 == *__first2))
1663  return false;
1664  return __first1 == __last1 && __first2 == __last2;
1665  }
1666  }
1667 
1668  // 4-iterator version of std::equal<It1, It2, BinaryPred> for use in C++11.
1669  template<typename _II1, typename _II2, typename _BinaryPredicate>
1670  _GLIBCXX20_CONSTEXPR
1671  inline bool
1672  __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2,
1673  _BinaryPredicate __binary_pred)
1674  {
1675  using _RATag = random_access_iterator_tag;
1676  using _Cat1 = decltype(std::__iter_concept_or_category<_II1>());
1677  using _Cat2 = decltype(std::__iter_concept_or_category<_II2>());
1678  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1679  if constexpr (_RAIters::value)
1680  {
1681  if ((__last1 - __first1) != (__last2 - __first2))
1682  return false;
1683  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1684  __binary_pred);
1685  }
1686  else
1687  {
1688  for (; __first1 != __last1 && __first2 != __last2;
1689  ++__first1, (void)++__first2)
1690  if (!bool(__binary_pred(*__first1, *__first2)))
1691  return false;
1692  return __first1 == __last1 && __first2 == __last2;
1693  }
1694  }
1695 #pragma GCC diagnostic pop
1696 #endif // C++11
1697 
1698 #ifdef __glibcxx_robust_nonmodifying_seq_ops // C++ >= 14
1699  /**
1700  * @brief Tests a range for element-wise equality.
1701  * @ingroup non_mutating_algorithms
1702  * @param __first1 An input iterator.
1703  * @param __last1 An input iterator.
1704  * @param __first2 An input iterator.
1705  * @param __last2 An input iterator.
1706  * @return A boolean true or false.
1707  *
1708  * This compares the elements of two ranges using @c == and returns true or
1709  * false depending on whether all of the corresponding elements of the
1710  * ranges are equal.
1711  */
1712  template<typename _II1, typename _II2>
1713  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1714  inline bool
1715  equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1716  {
1717  // concept requirements
1718  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1719  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1720  __glibcxx_function_requires(_EqualOpConcept<
1721  typename iterator_traits<_II1>::value_type,
1722  typename iterator_traits<_II2>::value_type>)
1723  __glibcxx_requires_valid_range(__first1, __last1);
1724  __glibcxx_requires_valid_range(__first2, __last2);
1725 
1726  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2);
1727  }
1728 
1729  /**
1730  * @brief Tests a range for element-wise equality.
1731  * @ingroup non_mutating_algorithms
1732  * @param __first1 An input iterator.
1733  * @param __last1 An input iterator.
1734  * @param __first2 An input iterator.
1735  * @param __last2 An input iterator.
1736  * @param __binary_pred A binary predicate @link functors
1737  * functor@endlink.
1738  * @return A boolean true or false.
1739  *
1740  * This compares the elements of two ranges using the binary_pred
1741  * parameter, and returns true or
1742  * false depending on whether all of the corresponding elements of the
1743  * ranges are equal.
1744  */
1745  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1746  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1747  inline bool
1748  equal(_IIter1 __first1, _IIter1 __last1,
1749  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1750  {
1751  // concept requirements
1752  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1753  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1754  __glibcxx_requires_valid_range(__first1, __last1);
1755  __glibcxx_requires_valid_range(__first2, __last2);
1756 
1757  return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2,
1758  __binary_pred);
1759  }
1760 #endif // __glibcxx_robust_nonmodifying_seq_ops
1761 
1762  /**
1763  * @brief Performs @b dictionary comparison on ranges.
1764  * @ingroup sorting_algorithms
1765  * @param __first1 An input iterator.
1766  * @param __last1 An input iterator.
1767  * @param __first2 An input iterator.
1768  * @param __last2 An input iterator.
1769  * @return A boolean true or false.
1770  *
1771  * <em>Returns true if the sequence of elements defined by the range
1772  * [first1,last1) is lexicographically less than the sequence of elements
1773  * defined by the range [first2,last2). Returns false otherwise.</em>
1774  * (Quoted from [25.3.8]/1.) If the iterators are all character pointers,
1775  * then this is an inline call to @c memcmp.
1776  */
1777  template<typename _II1, typename _II2>
1778  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1779  inline bool
1780  lexicographical_compare(_II1 __first1, _II1 __last1,
1781  _II2 __first2, _II2 __last2)
1782  {
1783 #ifdef _GLIBCXX_CONCEPT_CHECKS
1784  // concept requirements
1785  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1786  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1787 #endif
1788  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1789  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1790  __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1791  __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1792  __glibcxx_requires_valid_range(__first1, __last1);
1793  __glibcxx_requires_valid_range(__first2, __last2);
1794 
1795  return std::__lexicographical_compare_aux(__first1, __last1,
1796  __first2, __last2);
1797  }
1798 
1799  /**
1800  * @brief Performs @b dictionary comparison on ranges.
1801  * @ingroup sorting_algorithms
1802  * @param __first1 An input iterator.
1803  * @param __last1 An input iterator.
1804  * @param __first2 An input iterator.
1805  * @param __last2 An input iterator.
1806  * @param __comp A @link comparison_functors comparison functor@endlink.
1807  * @return A boolean true or false.
1808  *
1809  * The same as the four-parameter @c lexicographical_compare, but uses the
1810  * comp parameter instead of @c <.
1811  */
1812  template<typename _II1, typename _II2, typename _Compare>
1813  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1814  inline bool
1815  lexicographical_compare(_II1 __first1, _II1 __last1,
1816  _II2 __first2, _II2 __last2, _Compare __comp)
1817  {
1818  // concept requirements
1819  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1820  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1821  __glibcxx_requires_valid_range(__first1, __last1);
1822  __glibcxx_requires_valid_range(__first2, __last2);
1823 
1824  return std::__lexicographical_compare_impl
1825  (__first1, __last1, __first2, __last2, __comp);
1826  }
1827 
1828 #if __cpp_lib_three_way_comparison
1829  // Both iterators refer to contiguous ranges of unsigned narrow characters,
1830  // or std::byte, or big-endian unsigned integers, suitable for comparison
1831  // using memcmp.
1832  template<typename _Iter1, typename _Iter2>
1833  concept __memcmp_ordered_with
1834  = (__is_memcmp_ordered_with<iter_value_t<_Iter1>,
1835  iter_value_t<_Iter2>>::__value)
1836  && contiguous_iterator<_Iter1> && contiguous_iterator<_Iter2>;
1837 
1838  // Return a struct with two members, initialized to the smaller of x and y
1839  // (or x if they compare equal) and the result of the comparison x <=> y.
1840  template<typename _Tp>
1841  constexpr auto
1842  __min_cmp(_Tp __x, _Tp __y)
1843  {
1844  struct _Res {
1845  _Tp _M_min;
1846  decltype(__x <=> __y) _M_cmp;
1847  };
1848  auto __c = __x <=> __y;
1849  if (__c > 0)
1850  return _Res{__y, __c};
1851  return _Res{__x, __c};
1852  }
1853 
1854  /**
1855  * @brief Performs dictionary comparison on ranges.
1856  * @ingroup sorting_algorithms
1857  * @param __first1 An input iterator.
1858  * @param __last1 An input iterator.
1859  * @param __first2 An input iterator.
1860  * @param __last2 An input iterator.
1861  * @param __comp A @link comparison_functors comparison functor@endlink.
1862  * @return The comparison category that `__comp(*__first1, *__first2)`
1863  * returns.
1864  */
1865  template<typename _InputIter1, typename _InputIter2, typename _Comp>
1866  [[nodiscard]] constexpr auto
1867  lexicographical_compare_three_way(_InputIter1 __first1,
1868  _InputIter1 __last1,
1869  _InputIter2 __first2,
1870  _InputIter2 __last2,
1871  _Comp __comp)
1872  -> decltype(__comp(*__first1, *__first2))
1873  {
1874  // concept requirements
1875  __glibcxx_function_requires(_InputIteratorConcept<_InputIter1>)
1876  __glibcxx_function_requires(_InputIteratorConcept<_InputIter2>)
1877  __glibcxx_requires_valid_range(__first1, __last1);
1878  __glibcxx_requires_valid_range(__first2, __last2);
1879 
1880  using _Cat = decltype(__comp(*__first1, *__first2));
1881  static_assert(same_as<common_comparison_category_t<_Cat>, _Cat>);
1882 
1883  if (!std::__is_constant_evaluated())
1884  if constexpr (same_as<_Comp, __detail::_Synth3way>
1885  || same_as<_Comp, compare_three_way>)
1886  if constexpr (__memcmp_ordered_with<_InputIter1, _InputIter2>)
1887  {
1888  const auto [__len, __lencmp] = _GLIBCXX_STD_A::
1889  __min_cmp(__last1 - __first1, __last2 - __first2);
1890  if (__len)
1891  {
1892  const auto __blen = __len * sizeof(*__first1);
1893  const auto __c
1894  = __builtin_memcmp(&*__first1, &*__first2, __blen) <=> 0;
1895  if (__c != 0)
1896  return __c;
1897  }
1898  return __lencmp;
1899  }
1900 
1901  while (__first1 != __last1)
1902  {
1903  if (__first2 == __last2)
1904  return strong_ordering::greater;
1905  if (auto __cmp = __comp(*__first1, *__first2); __cmp != 0)
1906  return __cmp;
1907  ++__first1;
1908  ++__first2;
1909  }
1910  return (__first2 == __last2) <=> true; // See PR 94006
1911  }
1912 
1913  template<typename _InputIter1, typename _InputIter2>
1914  constexpr auto
1915  lexicographical_compare_three_way(_InputIter1 __first1,
1916  _InputIter1 __last1,
1917  _InputIter2 __first2,
1918  _InputIter2 __last2)
1919  {
1920  return _GLIBCXX_STD_A::
1921  lexicographical_compare_three_way(__first1, __last1, __first2, __last2,
1922  compare_three_way{});
1923  }
1924 #endif // three_way_comparison
1925 
1926  template<typename _InputIterator1, typename _InputIterator2,
1927  typename _BinaryPredicate>
1928  _GLIBCXX20_CONSTEXPR
1929  pair<_InputIterator1, _InputIterator2>
1930  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1931  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1932  {
1933  while (__first1 != __last1 && __binary_pred(*__first1, *__first2))
1934  {
1935  ++__first1;
1936  ++__first2;
1937  }
1938  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1939  }
1940 
1941  /**
1942  * @brief Finds the places in ranges which don't match.
1943  * @ingroup non_mutating_algorithms
1944  * @param __first1 An input iterator.
1945  * @param __last1 An input iterator.
1946  * @param __first2 An input iterator.
1947  * @return A pair of iterators pointing to the first mismatch.
1948  *
1949  * This compares the elements of two ranges using @c == and returns a pair
1950  * of iterators. The first iterator points into the first range, the
1951  * second iterator points into the second range, and the elements pointed
1952  * to by the iterators are not equal.
1953  */
1954  template<typename _InputIterator1, typename _InputIterator2>
1955  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1956  inline pair<_InputIterator1, _InputIterator2>
1957  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1958  _InputIterator2 __first2)
1959  {
1960  // concept requirements
1961  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1962  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1963  __glibcxx_function_requires(_EqualOpConcept<
1964  typename iterator_traits<_InputIterator1>::value_type,
1965  typename iterator_traits<_InputIterator2>::value_type>)
1966  __glibcxx_requires_valid_range(__first1, __last1);
1967 
1968  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1969  __gnu_cxx::__ops::equal_to());
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 __binary_pred A binary predicate @link functors
1979  * functor@endlink.
1980  * @return A pair of iterators pointing to the first mismatch.
1981  *
1982  * This compares the elements of two ranges using the binary_pred
1983  * parameter, and returns a pair
1984  * of iterators. The first iterator points into the first range, the
1985  * second iterator points into the second range, and the elements pointed
1986  * to by the iterators are not equal.
1987  */
1988  template<typename _InputIterator1, typename _InputIterator2,
1989  typename _BinaryPredicate>
1990  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
1991  inline pair<_InputIterator1, _InputIterator2>
1992  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1993  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1994  {
1995  // concept requirements
1996  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1997  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1998  __glibcxx_requires_valid_range(__first1, __last1);
1999 
2000  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
2001  __binary_pred);
2002  }
2003 
2004 #if __glibcxx_robust_nonmodifying_seq_ops // C++ >= 14
2005  template<typename _InputIterator1, typename _InputIterator2,
2006  typename _BinaryPredicate>
2007  _GLIBCXX20_CONSTEXPR
2008  pair<_InputIterator1, _InputIterator2>
2009  __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
2010  _InputIterator2 __first2, _InputIterator2 __last2,
2011  _BinaryPredicate __binary_pred)
2012  {
2013  while (__first1 != __last1 && __first2 != __last2
2014  && __binary_pred(*__first1, *__first2))
2015  {
2016  ++__first1;
2017  ++__first2;
2018  }
2019  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
2020  }
2021 
2022  /**
2023  * @brief Finds the places in ranges which don't match.
2024  * @ingroup non_mutating_algorithms
2025  * @param __first1 An input iterator.
2026  * @param __last1 An input iterator.
2027  * @param __first2 An input iterator.
2028  * @param __last2 An input iterator.
2029  * @return A pair of iterators pointing to the first mismatch.
2030  *
2031  * This compares the elements of two ranges using @c == and returns a pair
2032  * of iterators. The first iterator points into the first range, the
2033  * second iterator points into the second range, and the elements pointed
2034  * to by the iterators are not equal.
2035  */
2036  template<typename _InputIterator1, typename _InputIterator2>
2037  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
2038  inline pair<_InputIterator1, _InputIterator2>
2039  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
2040  _InputIterator2 __first2, _InputIterator2 __last2)
2041  {
2042  // concept requirements
2043  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2044  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2045  __glibcxx_function_requires(_EqualOpConcept<
2046  typename iterator_traits<_InputIterator1>::value_type,
2047  typename iterator_traits<_InputIterator2>::value_type>)
2048  __glibcxx_requires_valid_range(__first1, __last1);
2049  __glibcxx_requires_valid_range(__first2, __last2);
2050 
2051  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2052  __gnu_cxx::__ops::equal_to());
2053  }
2054 
2055  /**
2056  * @brief Finds the places in ranges which don't match.
2057  * @ingroup non_mutating_algorithms
2058  * @param __first1 An input iterator.
2059  * @param __last1 An input iterator.
2060  * @param __first2 An input iterator.
2061  * @param __last2 An input iterator.
2062  * @param __binary_pred A binary predicate @link functors
2063  * functor@endlink.
2064  * @return A pair of iterators pointing to the first mismatch.
2065  *
2066  * This compares the elements of two ranges using the binary_pred
2067  * parameter, and returns a pair
2068  * of iterators. The first iterator points into the first range, the
2069  * second iterator points into the second range, and the elements pointed
2070  * to by the iterators are not equal.
2071  */
2072  template<typename _InputIterator1, typename _InputIterator2,
2073  typename _BinaryPredicate>
2074  _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
2075  inline pair<_InputIterator1, _InputIterator2>
2076  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
2077  _InputIterator2 __first2, _InputIterator2 __last2,
2078  _BinaryPredicate __binary_pred)
2079  {
2080  // concept requirements
2081  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2082  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2083  __glibcxx_requires_valid_range(__first1, __last1);
2084  __glibcxx_requires_valid_range(__first2, __last2);
2085 
2086  return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
2087  __binary_pred);
2088  }
2089 #endif // __glibcxx_robust_nonmodifying_seq_ops
2090 
2091 _GLIBCXX_END_NAMESPACE_ALGO
2092 
2093  // Implementation of std::find_if, also used in std::remove_if and others.
2094  template<typename _Iterator, typename _Predicate>
2095  _GLIBCXX20_CONSTEXPR
2096  inline _Iterator
2097  __find_if(_Iterator __first, _Iterator __last, _Predicate __pred)
2098  {
2099 #pragma GCC unroll 4
2100  while (__first != __last && !__pred(*__first))
2101  ++__first;
2102  return __first;
2103  }
2104 
2105  template<typename _InputIterator, typename _Predicate>
2106  _GLIBCXX20_CONSTEXPR
2107  typename iterator_traits<_InputIterator>::difference_type
2108  __count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
2109  {
2110  typename iterator_traits<_InputIterator>::difference_type __n = 0;
2111  for (; __first != __last; ++__first)
2112  if (__pred(*__first))
2113  ++__n;
2114  return __n;
2115  }
2116 
2117  template<typename _ForwardIterator, typename _Predicate>
2118  _GLIBCXX20_CONSTEXPR
2119  _ForwardIterator
2120  __remove_if(_ForwardIterator __first, _ForwardIterator __last,
2121  _Predicate __pred)
2122  {
2123  __first = std::__find_if(__first, __last, __pred);
2124  if (__first == __last)
2125  return __first;
2126  _ForwardIterator __result = __first;
2127  ++__first;
2128  for (; __first != __last; ++__first)
2129  if (!__pred(*__first))
2130  {
2131  *__result = _GLIBCXX_MOVE(*__first);
2132  ++__result;
2133  }
2134  return __result;
2135  }
2136 
2137  template<typename _ForwardIterator1, typename _ForwardIterator2,
2138  typename _BinaryPredicate>
2139  _GLIBCXX20_CONSTEXPR
2140  _ForwardIterator1
2141  __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2142  _ForwardIterator2 __first2, _ForwardIterator2 __last2,
2143  _BinaryPredicate __predicate)
2144  {
2145  // Test for empty ranges
2146  if (__first1 == __last1 || __first2 == __last2)
2147  return __first1;
2148 
2149  __decltype(*__first2) __first2_val(*__first2);
2150  __decltype(__gnu_cxx::__ops::bind2nd(__predicate, __first2_val))
2151  __match_first = __gnu_cxx::__ops::bind2nd(__predicate, __first2_val);
2152 
2153  // Test for a pattern of length 1.
2154  _ForwardIterator2 __p1(__first2);
2155  if (++__p1 == __last2)
2156  return std::__find_if(__first1, __last1, __match_first);
2157 
2158  // General case.
2159  _ForwardIterator1 __current = __first1;
2160 
2161  for (;;)
2162  {
2163  __first1 = std::__find_if(__first1, __last1, __match_first);
2164 
2165  if (__first1 == __last1)
2166  return __last1;
2167 
2168  _ForwardIterator2 __p = __p1;
2169  __current = __first1;
2170  if (++__current == __last1)
2171  return __last1;
2172 
2173  while (__predicate(*__current, *__p))
2174  {
2175  if (++__p == __last2)
2176  return __first1;
2177  if (++__current == __last1)
2178  return __last1;
2179  }
2180  ++__first1;
2181  }
2182  return __first1;
2183  }
2184 #undef __match_first
2185 
2186 #if __cplusplus >= 201103L
2187  template<typename _ForwardIterator1, typename _ForwardIterator2,
2188  typename _BinaryPredicate>
2189  _GLIBCXX20_CONSTEXPR
2190  bool
2191  __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2192  _ForwardIterator2 __first2, _BinaryPredicate __pred)
2193  {
2194  // Efficiently compare identical prefixes: O(N) if sequences
2195  // have the same elements in the same order.
2196  for (; __first1 != __last1; ++__first1, (void)++__first2)
2197  if (!__pred(*__first1, *__first2))
2198  break;
2199 
2200  if (__first1 == __last1)
2201  return true;
2202 
2203  // Establish __last2 assuming equal ranges by iterating over the
2204  // rest of the list.
2205  _ForwardIterator2 __last2 = __first2;
2206  std::advance(__last2, std::distance(__first1, __last1));
2207  for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
2208  {
2209  auto&& __scan_val = *__scan;
2210  auto __scaneq = __gnu_cxx::__ops::bind1st(__pred, __scan_val);
2211  if (__scan != std::__find_if(__first1, __scan, __scaneq))
2212  continue; // We've seen this one before.
2213 
2214  auto __matches = std::__count_if(__first2, __last2, __scaneq);
2215  if (0 == __matches
2216  || std::__count_if(__scan, __last1, __scaneq) != __matches)
2217  return false;
2218  }
2219  return true;
2220  }
2221 
2222  /**
2223  * @brief Checks whether a permutation of the second sequence is equal
2224  * to the first sequence.
2225  * @ingroup non_mutating_algorithms
2226  * @param __first1 Start of first range.
2227  * @param __last1 End of first range.
2228  * @param __first2 Start of second range.
2229  * @return true if there exists a permutation of the elements in the range
2230  * [__first2, __first2 + (__last1 - __first1)), beginning with
2231  * ForwardIterator2 begin, such that equal(__first1, __last1, begin)
2232  * returns true; otherwise, returns false.
2233  */
2234  template<typename _ForwardIterator1, typename _ForwardIterator2>
2235  _GLIBCXX20_CONSTEXPR
2236  inline bool
2237  is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2238  _ForwardIterator2 __first2)
2239  {
2240  // concept requirements
2241  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
2242  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
2243  __glibcxx_function_requires(_EqualOpConcept<
2244  typename iterator_traits<_ForwardIterator1>::value_type,
2245  typename iterator_traits<_ForwardIterator2>::value_type>)
2246  __glibcxx_requires_valid_range(__first1, __last1);
2247 
2248  return std::__is_permutation(__first1, __last1, __first2,
2249  __gnu_cxx::__ops::equal_to());
2250  }
2251 #endif // C++11
2252 
2253 _GLIBCXX_BEGIN_NAMESPACE_ALGO
2254 
2255  /**
2256  * @brief Search a sequence for a matching sub-sequence using a predicate.
2257  * @ingroup non_mutating_algorithms
2258  * @param __first1 A forward iterator.
2259  * @param __last1 A forward iterator.
2260  * @param __first2 A forward iterator.
2261  * @param __last2 A forward iterator.
2262  * @param __predicate A binary predicate.
2263  * @return The first iterator @c i in the range
2264  * @p [__first1,__last1-(__last2-__first2)) such that
2265  * @p __predicate(*(i+N),*(__first2+N)) is true for each @c N in the range
2266  * @p [0,__last2-__first2), or @p __last1 if no such iterator exists.
2267  *
2268  * Searches the range @p [__first1,__last1) for a sub-sequence that
2269  * compares equal value-by-value with the sequence given by @p
2270  * [__first2,__last2), using @p __predicate to determine equality,
2271  * and returns an iterator to the first element of the
2272  * sub-sequence, or @p __last1 if no such iterator exists.
2273  *
2274  * @see search(_ForwardIter1, _ForwardIter1, _ForwardIter2, _ForwardIter2)
2275  */
2276  template<typename _ForwardIterator1, typename _ForwardIterator2,
2277  typename _BinaryPredicate>
2278  _GLIBCXX20_CONSTEXPR
2279  inline _ForwardIterator1
2280  search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
2281  _ForwardIterator2 __first2, _ForwardIterator2 __last2,
2282  _BinaryPredicate __predicate)
2283  {
2284  // concept requirements
2285  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
2286  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
2287  __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
2288  typename iterator_traits<_ForwardIterator1>::value_type,
2289  typename iterator_traits<_ForwardIterator2>::value_type>)
2290  __glibcxx_requires_valid_range(__first1, __last1);
2291  __glibcxx_requires_valid_range(__first2, __last2);
2292 
2293  return std::__search(__first1, __last1, __first2, __last2, __predicate);
2294  }
2295 
2296 _GLIBCXX_END_NAMESPACE_ALGO
2297 _GLIBCXX_END_NAMESPACE_VERSION
2298 } // namespace std
2299 
2300 // NB: This file is included within many other C++ includes, as a way
2301 // of getting the base algorithms. So, make sure that parallel bits
2302 // come in too if requested.
2303 #ifdef _GLIBCXX_PARALLEL
2304 # include <parallel/algobase.h>
2305 #endif
2306 
2307 #endif
algobase.h
Parallel STL function calls corresponding to the stl_algobase.h header. The functions defined here ma...
std::requires
requires requires
Definition: complex:1948
std::to_address
constexpr _Tp * to_address(_Tp *__ptr) noexcept
Obtain address referenced by a pointer to an object.
Definition: ptr_traits.h:232
std::make_unsigned_t
typename make_unsigned< _Tp >::type make_unsigned_t
Alias template for make_unsigned.
Definition: type_traits:2252
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:138
std::fill
constexpr void fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp &__value)
Fills the range [first,last) with copies of value.
Definition: stl_algobase.h:1001
std::copy
constexpr _OI copy(_II __first, _II __last, _OI __result)
Copies the range [first,last) into result.
Definition: stl_algobase.h:631
std::copy_backward
constexpr _BI2 copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
Copies the range [first,last) into result.
Definition: stl_algobase.h:835
std::move_backward
constexpr _BI2 move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
Moves the range [first,last) into result.
Definition: stl_algobase.h:871
std::fill_n
constexpr _OI fill_n(_OI __first, _Size __n, const _Tp &__value)
Fills the range [first,first+n) with copies of value.
Definition: stl_algobase.h:1179
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:1748
std::lexicographical_compare_three_way
constexpr auto lexicographical_compare_three_way(_InputIter1 __first1, _InputIter1 __last1, _InputIter2 __first2, _InputIter2 __last2, _Comp __comp) -> decltype(__comp(*__first1, *__first2))
Performs dictionary comparison on ranges.
Definition: stl_algobase.h:1867
std::max
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:256
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:232
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition: stl_iterator_base_types.h:241
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:172
std::same_as
concept same_as
[concept.same], concept same_as
Definition: concepts:65
std::__lg
constexpr _Tp __lg(_Tp __n)
This is a helper function for the sort routines and for random.tcc.
Definition: stl_algobase.h:1558
std::advance
constexpr void advance(_InputIterator &__i, _Distance __n)
A generalization of pointer arithmetic.
Definition: stl_iterator_base_funcs.h:261
__gnu_debug::_Safe_iterator
Safe iterator wrapper.
Definition: safe_iterator.h:133
std::iterator_traits
Traits class for iterators.
Definition: stl_iterator_base_types.h:180
std::equal_to< void >
One of the comparison functors.
Definition: stl_function.h:496
std::less< void >
One of the comparison functors.
Definition: stl_function.h:595
std::input_iterator_tag
Marking input iterators.
Definition: stl_iterator_base_types.h:95
std::output_iterator_tag
Marking output iterators.
Definition: stl_iterator_base_types.h:98
std::random_access_iterator_tag
Random-access iterators support a superset of bidirectional iterator operations.
Definition: stl_iterator_base_types.h:109
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