xref: /netbsd-src/external/gpl3/gcc/dist/libstdc++-v3/include/bits/stl_algobase.h (revision 6cd39ddb8550f6fa1bff3fed32053d7f19fd0453)
1 // Core algorithmic facilities -*- C++ -*-
2 
3 // Copyright (C) 2001-2015 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library.  This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /*
26  *
27  * Copyright (c) 1994
28  * Hewlett-Packard Company
29  *
30  * Permission to use, copy, modify, distribute and sell this software
31  * and its documentation for any purpose is hereby granted without fee,
32  * provided that the above copyright notice appear in all copies and
33  * that both that copyright notice and this permission notice appear
34  * in supporting documentation.  Hewlett-Packard Company makes no
35  * representations about the suitability of this software for any
36  * purpose.  It is provided "as is" without express or implied warranty.
37  *
38  *
39  * Copyright (c) 1996-1998
40  * Silicon Graphics Computer Systems, Inc.
41  *
42  * Permission to use, copy, modify, distribute and sell this software
43  * and its documentation for any purpose is hereby granted without fee,
44  * provided that the above copyright notice appear in all copies and
45  * that both that copyright notice and this permission notice appear
46  * in supporting documentation.  Silicon Graphics makes no
47  * representations about the suitability of this software for any
48  * purpose.  It is provided "as is" without express or implied warranty.
49  */
50 
51 /** @file bits/stl_algobase.h
52  *  This is an internal header file, included by other library headers.
53  *  Do not attempt to use it directly. @headername{algorithm}
54  */
55 
56 #ifndef _STL_ALGOBASE_H
57 #define _STL_ALGOBASE_H 1
58 
59 #include <bits/c++config.h>
60 #include <bits/functexcept.h>
61 #include <bits/cpp_type_traits.h>
62 #include <ext/type_traits.h>
63 #include <ext/numeric_traits.h>
64 #include <bits/stl_pair.h>
65 #include <bits/stl_iterator_base_types.h>
66 #include <bits/stl_iterator_base_funcs.h>
67 #include <bits/stl_iterator.h>
68 #include <bits/concept_check.h>
69 #include <debug/debug.h>
70 #include <bits/move.h> // For std::swap and _GLIBCXX_MOVE
71 #include <bits/predefined_ops.h>
72 
73 namespace std _GLIBCXX_VISIBILITY(default)
74 {
75 _GLIBCXX_BEGIN_NAMESPACE_VERSION
76 
77 #if __cplusplus < 201103L
78   // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
79   // nutshell, we are partially implementing the resolution of DR 187,
80   // when it's safe, i.e., the value_types are equal.
81   template<bool _BoolType>
82     struct __iter_swap
83     {
84       template<typename _ForwardIterator1, typename _ForwardIterator2>
85         static void
86         iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
87         {
88           typedef typename iterator_traits<_ForwardIterator1>::value_type
89             _ValueType1;
90           _ValueType1 __tmp = _GLIBCXX_MOVE(*__a);
91           *__a = _GLIBCXX_MOVE(*__b);
92           *__b = _GLIBCXX_MOVE(__tmp);
93 	}
94     };
95 
96   template<>
97     struct __iter_swap<true>
98     {
99       template<typename _ForwardIterator1, typename _ForwardIterator2>
100         static void
101         iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
102         {
103           swap(*__a, *__b);
104         }
105     };
106 #endif
107 
108   /**
109    *  @brief Swaps the contents of two iterators.
110    *  @ingroup mutating_algorithms
111    *  @param  __a  An iterator.
112    *  @param  __b  Another iterator.
113    *  @return   Nothing.
114    *
115    *  This function swaps the values pointed to by two iterators, not the
116    *  iterators themselves.
117   */
118   template<typename _ForwardIterator1, typename _ForwardIterator2>
119     inline void
120     iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
121     {
122       // concept requirements
123       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
124 				  _ForwardIterator1>)
125       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
126 				  _ForwardIterator2>)
127 
128 #if __cplusplus < 201103L
129       typedef typename iterator_traits<_ForwardIterator1>::value_type
130 	_ValueType1;
131       typedef typename iterator_traits<_ForwardIterator2>::value_type
132 	_ValueType2;
133 
134       __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
135 				  _ValueType2>)
136       __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
137 				  _ValueType1>)
138 
139       typedef typename iterator_traits<_ForwardIterator1>::reference
140 	_ReferenceType1;
141       typedef typename iterator_traits<_ForwardIterator2>::reference
142 	_ReferenceType2;
143       std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
144 	&& __are_same<_ValueType1&, _ReferenceType1>::__value
145 	&& __are_same<_ValueType2&, _ReferenceType2>::__value>::
146 	iter_swap(__a, __b);
147 #else
148       swap(*__a, *__b);
149 #endif
150     }
151 
152   /**
153    *  @brief Swap the elements of two sequences.
154    *  @ingroup mutating_algorithms
155    *  @param  __first1  A forward iterator.
156    *  @param  __last1   A forward iterator.
157    *  @param  __first2  A forward iterator.
158    *  @return   An iterator equal to @p first2+(last1-first1).
159    *
160    *  Swaps each element in the range @p [first1,last1) with the
161    *  corresponding element in the range @p [first2,(last1-first1)).
162    *  The ranges must not overlap.
163   */
164   template<typename _ForwardIterator1, typename _ForwardIterator2>
165     _ForwardIterator2
166     swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
167 		_ForwardIterator2 __first2)
168     {
169       // concept requirements
170       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
171 				  _ForwardIterator1>)
172       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
173 				  _ForwardIterator2>)
174       __glibcxx_requires_valid_range(__first1, __last1);
175 
176       for (; __first1 != __last1; ++__first1, ++__first2)
177 	std::iter_swap(__first1, __first2);
178       return __first2;
179     }
180 
181   /**
182    *  @brief This does what you think it does.
183    *  @ingroup sorting_algorithms
184    *  @param  __a  A thing of arbitrary type.
185    *  @param  __b  Another thing of arbitrary type.
186    *  @return   The lesser of the parameters.
187    *
188    *  This is the simple classic generic implementation.  It will work on
189    *  temporary expressions, since they are only evaluated once, unlike a
190    *  preprocessor macro.
191   */
192   template<typename _Tp>
193     _GLIBCXX14_CONSTEXPR
194     inline const _Tp&
195     min(const _Tp& __a, const _Tp& __b)
196     {
197       // concept requirements
198       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
199       //return __b < __a ? __b : __a;
200       if (__b < __a)
201 	return __b;
202       return __a;
203     }
204 
205   /**
206    *  @brief This does what you think it does.
207    *  @ingroup sorting_algorithms
208    *  @param  __a  A thing of arbitrary type.
209    *  @param  __b  Another thing of arbitrary type.
210    *  @return   The greater of the parameters.
211    *
212    *  This is the simple classic generic implementation.  It will work on
213    *  temporary expressions, since they are only evaluated once, unlike a
214    *  preprocessor macro.
215   */
216   template<typename _Tp>
217     _GLIBCXX14_CONSTEXPR
218     inline const _Tp&
219     max(const _Tp& __a, const _Tp& __b)
220     {
221       // concept requirements
222       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
223       //return  __a < __b ? __b : __a;
224       if (__a < __b)
225 	return __b;
226       return __a;
227     }
228 
229   /**
230    *  @brief This does what you think it does.
231    *  @ingroup sorting_algorithms
232    *  @param  __a  A thing of arbitrary type.
233    *  @param  __b  Another thing of arbitrary type.
234    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
235    *  @return   The lesser of the parameters.
236    *
237    *  This will work on temporary expressions, since they are only evaluated
238    *  once, unlike a preprocessor macro.
239   */
240   template<typename _Tp, typename _Compare>
241     _GLIBCXX14_CONSTEXPR
242     inline const _Tp&
243     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
244     {
245       //return __comp(__b, __a) ? __b : __a;
246       if (__comp(__b, __a))
247 	return __b;
248       return __a;
249     }
250 
251   /**
252    *  @brief This does what you think it does.
253    *  @ingroup sorting_algorithms
254    *  @param  __a  A thing of arbitrary type.
255    *  @param  __b  Another thing of arbitrary type.
256    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
257    *  @return   The greater of the parameters.
258    *
259    *  This will work on temporary expressions, since they are only evaluated
260    *  once, unlike a preprocessor macro.
261   */
262   template<typename _Tp, typename _Compare>
263     _GLIBCXX14_CONSTEXPR
264     inline const _Tp&
265     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
266     {
267       //return __comp(__a, __b) ? __b : __a;
268       if (__comp(__a, __b))
269 	return __b;
270       return __a;
271     }
272 
273   // If _Iterator is a __normal_iterator return its base (a plain pointer,
274   // normally) otherwise return it untouched.  See copy, fill, ...
275   template<typename _Iterator>
276     struct _Niter_base
277     : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
278     { };
279 
280   template<typename _Iterator>
281     inline typename _Niter_base<_Iterator>::iterator_type
282     __niter_base(_Iterator __it)
283     { return std::_Niter_base<_Iterator>::_S_base(__it); }
284 
285   // Likewise, for move_iterator.
286   template<typename _Iterator>
287     struct _Miter_base
288     : _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
289     { };
290 
291   template<typename _Iterator>
292     inline typename _Miter_base<_Iterator>::iterator_type
293     __miter_base(_Iterator __it)
294     { return std::_Miter_base<_Iterator>::_S_base(__it); }
295 
296   // All of these auxiliary structs serve two purposes.  (1) Replace
297   // calls to copy with memmove whenever possible.  (Memmove, not memcpy,
298   // because the input and output ranges are permitted to overlap.)
299   // (2) If we're using random access iterators, then write the loop as
300   // a for loop with an explicit count.
301 
302   template<bool, bool, typename>
303     struct __copy_move
304     {
305       template<typename _II, typename _OI>
306         static _OI
307         __copy_m(_II __first, _II __last, _OI __result)
308         {
309 	  for (; __first != __last; ++__result, ++__first)
310 	    *__result = *__first;
311 	  return __result;
312 	}
313     };
314 
315 #if __cplusplus >= 201103L
316   template<typename _Category>
317     struct __copy_move<true, false, _Category>
318     {
319       template<typename _II, typename _OI>
320         static _OI
321         __copy_m(_II __first, _II __last, _OI __result)
322         {
323 	  for (; __first != __last; ++__result, ++__first)
324 	    *__result = std::move(*__first);
325 	  return __result;
326 	}
327     };
328 #endif
329 
330   template<>
331     struct __copy_move<false, false, random_access_iterator_tag>
332     {
333       template<typename _II, typename _OI>
334         static _OI
335         __copy_m(_II __first, _II __last, _OI __result)
336         {
337 	  typedef typename iterator_traits<_II>::difference_type _Distance;
338 	  for(_Distance __n = __last - __first; __n > 0; --__n)
339 	    {
340 	      *__result = *__first;
341 	      ++__first;
342 	      ++__result;
343 	    }
344 	  return __result;
345 	}
346     };
347 
348 #if __cplusplus >= 201103L
349   template<>
350     struct __copy_move<true, false, random_access_iterator_tag>
351     {
352       template<typename _II, typename _OI>
353         static _OI
354         __copy_m(_II __first, _II __last, _OI __result)
355         {
356 	  typedef typename iterator_traits<_II>::difference_type _Distance;
357 	  for(_Distance __n = __last - __first; __n > 0; --__n)
358 	    {
359 	      *__result = std::move(*__first);
360 	      ++__first;
361 	      ++__result;
362 	    }
363 	  return __result;
364 	}
365     };
366 #endif
367 
368   template<bool _IsMove>
369     struct __copy_move<_IsMove, true, random_access_iterator_tag>
370     {
371       template<typename _Tp>
372         static _Tp*
373         __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
374         {
375 #if __cplusplus >= 201103L
376 	  // trivial types can have deleted assignment
377 	  static_assert( is_copy_assignable<_Tp>::value,
378 	                 "type is not assignable" );
379 #endif
380 	  const ptrdiff_t _Num = __last - __first;
381 	  if (_Num)
382 	    __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
383 	  return __result + _Num;
384 	}
385     };
386 
387   template<bool _IsMove, typename _II, typename _OI>
388     inline _OI
389     __copy_move_a(_II __first, _II __last, _OI __result)
390     {
391       typedef typename iterator_traits<_II>::value_type _ValueTypeI;
392       typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
393       typedef typename iterator_traits<_II>::iterator_category _Category;
394       const bool __simple = (__is_trivial(_ValueTypeI)
395 	                     && __is_pointer<_II>::__value
396 	                     && __is_pointer<_OI>::__value
397 			     && __are_same<_ValueTypeI, _ValueTypeO>::__value);
398 
399       return std::__copy_move<_IsMove, __simple,
400 	                      _Category>::__copy_m(__first, __last, __result);
401     }
402 
403   // Helpers for streambuf iterators (either istream or ostream).
404   // NB: avoid including <iosfwd>, relatively large.
405   template<typename _CharT>
406     struct char_traits;
407 
408   template<typename _CharT, typename _Traits>
409     class istreambuf_iterator;
410 
411   template<typename _CharT, typename _Traits>
412     class ostreambuf_iterator;
413 
414   template<bool _IsMove, typename _CharT>
415     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
416 	     ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
417     __copy_move_a2(_CharT*, _CharT*,
418 		   ostreambuf_iterator<_CharT, char_traits<_CharT> >);
419 
420   template<bool _IsMove, typename _CharT>
421     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
422 	     ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
423     __copy_move_a2(const _CharT*, const _CharT*,
424 		   ostreambuf_iterator<_CharT, char_traits<_CharT> >);
425 
426   template<bool _IsMove, typename _CharT>
427     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
428 				    _CharT*>::__type
429     __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
430 		   istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
431 
432   template<bool _IsMove, typename _II, typename _OI>
433     inline _OI
434     __copy_move_a2(_II __first, _II __last, _OI __result)
435     {
436       return _OI(std::__copy_move_a<_IsMove>(std::__niter_base(__first),
437 					     std::__niter_base(__last),
438 					     std::__niter_base(__result)));
439     }
440 
441   /**
442    *  @brief Copies the range [first,last) into result.
443    *  @ingroup mutating_algorithms
444    *  @param  __first  An input iterator.
445    *  @param  __last   An input iterator.
446    *  @param  __result An output iterator.
447    *  @return   result + (first - last)
448    *
449    *  This inline function will boil down to a call to @c memmove whenever
450    *  possible.  Failing that, if random access iterators are passed, then the
451    *  loop count will be known (and therefore a candidate for compiler
452    *  optimizations such as unrolling).  Result may not be contained within
453    *  [first,last); the copy_backward function should be used instead.
454    *
455    *  Note that the end of the output range is permitted to be contained
456    *  within [first,last).
457   */
458   template<typename _II, typename _OI>
459     inline _OI
460     copy(_II __first, _II __last, _OI __result)
461     {
462       // concept requirements
463       __glibcxx_function_requires(_InputIteratorConcept<_II>)
464       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
465 	    typename iterator_traits<_II>::value_type>)
466       __glibcxx_requires_valid_range(__first, __last);
467 
468       return (std::__copy_move_a2<__is_move_iterator<_II>::__value>
469 	      (std::__miter_base(__first), std::__miter_base(__last),
470 	       __result));
471     }
472 
473 #if __cplusplus >= 201103L
474   /**
475    *  @brief Moves the range [first,last) into result.
476    *  @ingroup mutating_algorithms
477    *  @param  __first  An input iterator.
478    *  @param  __last   An input iterator.
479    *  @param  __result An output iterator.
480    *  @return   result + (first - last)
481    *
482    *  This inline function will boil down to a call to @c memmove whenever
483    *  possible.  Failing that, if random access iterators are passed, then the
484    *  loop count will be known (and therefore a candidate for compiler
485    *  optimizations such as unrolling).  Result may not be contained within
486    *  [first,last); the move_backward function should be used instead.
487    *
488    *  Note that the end of the output range is permitted to be contained
489    *  within [first,last).
490   */
491   template<typename _II, typename _OI>
492     inline _OI
493     move(_II __first, _II __last, _OI __result)
494     {
495       // concept requirements
496       __glibcxx_function_requires(_InputIteratorConcept<_II>)
497       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
498 	    typename iterator_traits<_II>::value_type>)
499       __glibcxx_requires_valid_range(__first, __last);
500 
501       return std::__copy_move_a2<true>(std::__miter_base(__first),
502 				       std::__miter_base(__last), __result);
503     }
504 
505 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
506 #else
507 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
508 #endif
509 
510   template<bool, bool, typename>
511     struct __copy_move_backward
512     {
513       template<typename _BI1, typename _BI2>
514         static _BI2
515         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
516         {
517 	  while (__first != __last)
518 	    *--__result = *--__last;
519 	  return __result;
520 	}
521     };
522 
523 #if __cplusplus >= 201103L
524   template<typename _Category>
525     struct __copy_move_backward<true, false, _Category>
526     {
527       template<typename _BI1, typename _BI2>
528         static _BI2
529         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
530         {
531 	  while (__first != __last)
532 	    *--__result = std::move(*--__last);
533 	  return __result;
534 	}
535     };
536 #endif
537 
538   template<>
539     struct __copy_move_backward<false, false, random_access_iterator_tag>
540     {
541       template<typename _BI1, typename _BI2>
542         static _BI2
543         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
544         {
545 	  typename iterator_traits<_BI1>::difference_type __n;
546 	  for (__n = __last - __first; __n > 0; --__n)
547 	    *--__result = *--__last;
548 	  return __result;
549 	}
550     };
551 
552 #if __cplusplus >= 201103L
553   template<>
554     struct __copy_move_backward<true, false, random_access_iterator_tag>
555     {
556       template<typename _BI1, typename _BI2>
557         static _BI2
558         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
559         {
560 	  typename iterator_traits<_BI1>::difference_type __n;
561 	  for (__n = __last - __first; __n > 0; --__n)
562 	    *--__result = std::move(*--__last);
563 	  return __result;
564 	}
565     };
566 #endif
567 
568   template<bool _IsMove>
569     struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
570     {
571       template<typename _Tp>
572         static _Tp*
573         __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
574         {
575 #if __cplusplus >= 201103L
576 	  // trivial types can have deleted assignment
577 	  static_assert( is_copy_assignable<_Tp>::value,
578 	                 "type is not assignable" );
579 #endif
580 	  const ptrdiff_t _Num = __last - __first;
581 	  if (_Num)
582 	    __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
583 	  return __result - _Num;
584 	}
585     };
586 
587   template<bool _IsMove, typename _BI1, typename _BI2>
588     inline _BI2
589     __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
590     {
591       typedef typename iterator_traits<_BI1>::value_type _ValueType1;
592       typedef typename iterator_traits<_BI2>::value_type _ValueType2;
593       typedef typename iterator_traits<_BI1>::iterator_category _Category;
594       const bool __simple = (__is_trivial(_ValueType1)
595 	                     && __is_pointer<_BI1>::__value
596 	                     && __is_pointer<_BI2>::__value
597 			     && __are_same<_ValueType1, _ValueType2>::__value);
598 
599       return std::__copy_move_backward<_IsMove, __simple,
600 	                               _Category>::__copy_move_b(__first,
601 								 __last,
602 								 __result);
603     }
604 
605   template<bool _IsMove, typename _BI1, typename _BI2>
606     inline _BI2
607     __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
608     {
609       return _BI2(std::__copy_move_backward_a<_IsMove>
610 		  (std::__niter_base(__first), std::__niter_base(__last),
611 		   std::__niter_base(__result)));
612     }
613 
614   /**
615    *  @brief Copies the range [first,last) into result.
616    *  @ingroup mutating_algorithms
617    *  @param  __first  A bidirectional iterator.
618    *  @param  __last   A bidirectional iterator.
619    *  @param  __result A bidirectional iterator.
620    *  @return   result - (first - last)
621    *
622    *  The function has the same effect as copy, but starts at the end of the
623    *  range and works its way to the start, returning the start of the result.
624    *  This inline function will boil down to a call to @c memmove whenever
625    *  possible.  Failing that, if random access iterators are passed, then the
626    *  loop count will be known (and therefore a candidate for compiler
627    *  optimizations such as unrolling).
628    *
629    *  Result may not be in the range (first,last].  Use copy instead.  Note
630    *  that the start of the output range may overlap [first,last).
631   */
632   template<typename _BI1, typename _BI2>
633     inline _BI2
634     copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
635     {
636       // concept requirements
637       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
638       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
639       __glibcxx_function_requires(_ConvertibleConcept<
640 	    typename iterator_traits<_BI1>::value_type,
641 	    typename iterator_traits<_BI2>::value_type>)
642       __glibcxx_requires_valid_range(__first, __last);
643 
644       return (std::__copy_move_backward_a2<__is_move_iterator<_BI1>::__value>
645 	      (std::__miter_base(__first), std::__miter_base(__last),
646 	       __result));
647     }
648 
649 #if __cplusplus >= 201103L
650   /**
651    *  @brief Moves the range [first,last) into result.
652    *  @ingroup mutating_algorithms
653    *  @param  __first  A bidirectional iterator.
654    *  @param  __last   A bidirectional iterator.
655    *  @param  __result A bidirectional iterator.
656    *  @return   result - (first - last)
657    *
658    *  The function has the same effect as move, but starts at the end of the
659    *  range and works its way to the start, returning the start of the result.
660    *  This inline function will boil down to a call to @c memmove whenever
661    *  possible.  Failing that, if random access iterators are passed, then the
662    *  loop count will be known (and therefore a candidate for compiler
663    *  optimizations such as unrolling).
664    *
665    *  Result may not be in the range (first,last].  Use move instead.  Note
666    *  that the start of the output range may overlap [first,last).
667   */
668   template<typename _BI1, typename _BI2>
669     inline _BI2
670     move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
671     {
672       // concept requirements
673       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
674       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
675       __glibcxx_function_requires(_ConvertibleConcept<
676 	    typename iterator_traits<_BI1>::value_type,
677 	    typename iterator_traits<_BI2>::value_type>)
678       __glibcxx_requires_valid_range(__first, __last);
679 
680       return std::__copy_move_backward_a2<true>(std::__miter_base(__first),
681 						std::__miter_base(__last),
682 						__result);
683     }
684 
685 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
686 #else
687 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
688 #endif
689 
690   template<typename _ForwardIterator, typename _Tp>
691     inline typename
692     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
693     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
694  	     const _Tp& __value)
695     {
696       for (; __first != __last; ++__first)
697 	*__first = __value;
698     }
699 
700   template<typename _ForwardIterator, typename _Tp>
701     inline typename
702     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
703     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
704 	     const _Tp& __value)
705     {
706       const _Tp __tmp = __value;
707       for (; __first != __last; ++__first)
708 	*__first = __tmp;
709     }
710 
711   // Specialization: for char types we can use memset.
712   template<typename _Tp>
713     inline typename
714     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
715     __fill_a(_Tp* __first, _Tp* __last, const _Tp& __c)
716     {
717       const _Tp __tmp = __c;
718       if (const size_t __len = __last - __first)
719 	__builtin_memset(__first, static_cast<unsigned char>(__tmp), __len);
720     }
721 
722   /**
723    *  @brief Fills the range [first,last) with copies of value.
724    *  @ingroup mutating_algorithms
725    *  @param  __first  A forward iterator.
726    *  @param  __last   A forward iterator.
727    *  @param  __value  A reference-to-const of arbitrary type.
728    *  @return   Nothing.
729    *
730    *  This function fills a range with copies of the same value.  For char
731    *  types filling contiguous areas of memory, this becomes an inline call
732    *  to @c memset or @c wmemset.
733   */
734   template<typename _ForwardIterator, typename _Tp>
735     inline void
736     fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
737     {
738       // concept requirements
739       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
740 				  _ForwardIterator>)
741       __glibcxx_requires_valid_range(__first, __last);
742 
743       std::__fill_a(std::__niter_base(__first), std::__niter_base(__last),
744 		    __value);
745     }
746 
747   template<typename _OutputIterator, typename _Size, typename _Tp>
748     inline typename
749     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
750     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
751     {
752       for (__decltype(__n + 0) __niter = __n;
753 	   __niter > 0; --__niter, ++__first)
754 	*__first = __value;
755       return __first;
756     }
757 
758   template<typename _OutputIterator, typename _Size, typename _Tp>
759     inline typename
760     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
761     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
762     {
763       const _Tp __tmp = __value;
764       for (__decltype(__n + 0) __niter = __n;
765 	   __niter > 0; --__niter, ++__first)
766 	*__first = __tmp;
767       return __first;
768     }
769 
770   template<typename _Size, typename _Tp>
771     inline typename
772     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, _Tp*>::__type
773     __fill_n_a(_Tp* __first, _Size __n, const _Tp& __c)
774     {
775       std::__fill_a(__first, __first + __n, __c);
776       return __first + __n;
777     }
778 
779   /**
780    *  @brief Fills the range [first,first+n) with copies of value.
781    *  @ingroup mutating_algorithms
782    *  @param  __first  An output iterator.
783    *  @param  __n      The count of copies to perform.
784    *  @param  __value  A reference-to-const of arbitrary type.
785    *  @return   The iterator at first+n.
786    *
787    *  This function fills a range with copies of the same value.  For char
788    *  types filling contiguous areas of memory, this becomes an inline call
789    *  to @c memset or @ wmemset.
790    *
791    *  _GLIBCXX_RESOLVE_LIB_DEFECTS
792    *  DR 865. More algorithms that throw away information
793   */
794   template<typename _OI, typename _Size, typename _Tp>
795     inline _OI
796     fill_n(_OI __first, _Size __n, const _Tp& __value)
797     {
798       // concept requirements
799       __glibcxx_function_requires(_OutputIteratorConcept<_OI, _Tp>)
800 
801       return _OI(std::__fill_n_a(std::__niter_base(__first), __n, __value));
802     }
803 
804   template<bool _BoolType>
805     struct __equal
806     {
807       template<typename _II1, typename _II2>
808         static bool
809         equal(_II1 __first1, _II1 __last1, _II2 __first2)
810         {
811 	  for (; __first1 != __last1; ++__first1, ++__first2)
812 	    if (!(*__first1 == *__first2))
813 	      return false;
814 	  return true;
815 	}
816     };
817 
818   template<>
819     struct __equal<true>
820     {
821       template<typename _Tp>
822         static bool
823         equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
824         {
825 	  if (const size_t __len = (__last1 - __first1))
826 	    return !__builtin_memcmp(__first1, __first2, sizeof(_Tp) * __len);
827 	  return true;
828 	}
829     };
830 
831   template<typename _II1, typename _II2>
832     inline bool
833     __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
834     {
835       typedef typename iterator_traits<_II1>::value_type _ValueType1;
836       typedef typename iterator_traits<_II2>::value_type _ValueType2;
837       const bool __simple = ((__is_integer<_ValueType1>::__value
838 			      || __is_pointer<_ValueType1>::__value)
839 	                     && __is_pointer<_II1>::__value
840 	                     && __is_pointer<_II2>::__value
841 			     && __are_same<_ValueType1, _ValueType2>::__value);
842 
843       return std::__equal<__simple>::equal(__first1, __last1, __first2);
844     }
845 
846   template<typename, typename>
847     struct __lc_rai
848     {
849       template<typename _II1, typename _II2>
850         static _II1
851         __newlast1(_II1, _II1 __last1, _II2, _II2)
852         { return __last1; }
853 
854       template<typename _II>
855         static bool
856         __cnd2(_II __first, _II __last)
857         { return __first != __last; }
858     };
859 
860   template<>
861     struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
862     {
863       template<typename _RAI1, typename _RAI2>
864         static _RAI1
865         __newlast1(_RAI1 __first1, _RAI1 __last1,
866 		   _RAI2 __first2, _RAI2 __last2)
867         {
868 	  const typename iterator_traits<_RAI1>::difference_type
869 	    __diff1 = __last1 - __first1;
870 	  const typename iterator_traits<_RAI2>::difference_type
871 	    __diff2 = __last2 - __first2;
872 	  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
873 	}
874 
875       template<typename _RAI>
876         static bool
877         __cnd2(_RAI, _RAI)
878         { return true; }
879     };
880 
881   template<typename _II1, typename _II2, typename _Compare>
882     bool
883     __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
884 				   _II2 __first2, _II2 __last2,
885 				   _Compare __comp)
886     {
887       typedef typename iterator_traits<_II1>::iterator_category _Category1;
888       typedef typename iterator_traits<_II2>::iterator_category _Category2;
889       typedef std::__lc_rai<_Category1, _Category2> __rai_type;
890 
891       __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
892       for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
893 	   ++__first1, ++__first2)
894 	{
895 	  if (__comp(__first1, __first2))
896 	    return true;
897 	  if (__comp(__first2, __first1))
898 	    return false;
899 	}
900       return __first1 == __last1 && __first2 != __last2;
901     }
902 
903   template<bool _BoolType>
904     struct __lexicographical_compare
905     {
906       template<typename _II1, typename _II2>
907         static bool __lc(_II1, _II1, _II2, _II2);
908     };
909 
910   template<bool _BoolType>
911     template<typename _II1, typename _II2>
912       bool
913       __lexicographical_compare<_BoolType>::
914       __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
915       {
916 	return std::__lexicographical_compare_impl(__first1, __last1,
917 						   __first2, __last2,
918 					__gnu_cxx::__ops::__iter_less_iter());
919       }
920 
921   template<>
922     struct __lexicographical_compare<true>
923     {
924       template<typename _Tp, typename _Up>
925         static bool
926         __lc(const _Tp* __first1, const _Tp* __last1,
927 	     const _Up* __first2, const _Up* __last2)
928 	{
929 	  const size_t __len1 = __last1 - __first1;
930 	  const size_t __len2 = __last2 - __first2;
931 	  if (const size_t __len = std::min(__len1, __len2))
932 	    if (int __result = __builtin_memcmp(__first1, __first2, __len))
933 	      return __result < 0;
934 	  return __len1 < __len2;
935 	}
936     };
937 
938   template<typename _II1, typename _II2>
939     inline bool
940     __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
941 				  _II2 __first2, _II2 __last2)
942     {
943       typedef typename iterator_traits<_II1>::value_type _ValueType1;
944       typedef typename iterator_traits<_II2>::value_type _ValueType2;
945       const bool __simple =
946 	(__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
947 	 && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed_val
948 	 && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed_val
949 	 && __is_pointer<_II1>::__value
950 	 && __is_pointer<_II2>::__value);
951 
952       return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
953 							    __first2, __last2);
954     }
955 
956   template<typename _ForwardIterator, typename _Tp, typename _Compare>
957     _ForwardIterator
958     __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
959 		  const _Tp& __val, _Compare __comp)
960     {
961       typedef typename iterator_traits<_ForwardIterator>::difference_type
962 	_DistanceType;
963 
964       _DistanceType __len = std::distance(__first, __last);
965 
966       while (__len > 0)
967 	{
968 	  _DistanceType __half = __len >> 1;
969 	  _ForwardIterator __middle = __first;
970 	  std::advance(__middle, __half);
971 	  if (__comp(__middle, __val))
972 	    {
973 	      __first = __middle;
974 	      ++__first;
975 	      __len = __len - __half - 1;
976 	    }
977 	  else
978 	    __len = __half;
979 	}
980       return __first;
981     }
982 
983   /**
984    *  @brief Finds the first position in which @a val could be inserted
985    *         without changing the ordering.
986    *  @param  __first   An iterator.
987    *  @param  __last    Another iterator.
988    *  @param  __val     The search term.
989    *  @return         An iterator pointing to the first element <em>not less
990    *                  than</em> @a val, or end() if every element is less than
991    *                  @a val.
992    *  @ingroup binary_search_algorithms
993   */
994   template<typename _ForwardIterator, typename _Tp>
995     inline _ForwardIterator
996     lower_bound(_ForwardIterator __first, _ForwardIterator __last,
997 		const _Tp& __val)
998     {
999       // concept requirements
1000       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
1001       __glibcxx_function_requires(_LessThanOpConcept<
1002 	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
1003       __glibcxx_requires_partitioned_lower(__first, __last, __val);
1004 
1005       return std::__lower_bound(__first, __last, __val,
1006 				__gnu_cxx::__ops::__iter_less_val());
1007     }
1008 
1009   /// This is a helper function for the sort routines and for random.tcc.
1010   //  Precondition: __n > 0.
1011   inline _GLIBCXX_CONSTEXPR int
1012   __lg(int __n)
1013   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1014 
1015   inline _GLIBCXX_CONSTEXPR unsigned
1016   __lg(unsigned __n)
1017   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1018 
1019   inline _GLIBCXX_CONSTEXPR long
1020   __lg(long __n)
1021   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1022 
1023   inline _GLIBCXX_CONSTEXPR unsigned long
1024   __lg(unsigned long __n)
1025   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1026 
1027   inline _GLIBCXX_CONSTEXPR long long
1028   __lg(long long __n)
1029   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1030 
1031   inline _GLIBCXX_CONSTEXPR unsigned long long
1032   __lg(unsigned long long __n)
1033   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1034 
1035 _GLIBCXX_END_NAMESPACE_VERSION
1036 
1037 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1038 
1039   /**
1040    *  @brief Tests a range for element-wise equality.
1041    *  @ingroup non_mutating_algorithms
1042    *  @param  __first1  An input iterator.
1043    *  @param  __last1   An input iterator.
1044    *  @param  __first2  An input iterator.
1045    *  @return   A boolean true or false.
1046    *
1047    *  This compares the elements of two ranges using @c == and returns true or
1048    *  false depending on whether all of the corresponding elements of the
1049    *  ranges are equal.
1050   */
1051   template<typename _II1, typename _II2>
1052     inline bool
1053     equal(_II1 __first1, _II1 __last1, _II2 __first2)
1054     {
1055       // concept requirements
1056       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1057       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1058       __glibcxx_function_requires(_EqualOpConcept<
1059 	    typename iterator_traits<_II1>::value_type,
1060 	    typename iterator_traits<_II2>::value_type>)
1061       __glibcxx_requires_valid_range(__first1, __last1);
1062 
1063       return std::__equal_aux(std::__niter_base(__first1),
1064 			      std::__niter_base(__last1),
1065 			      std::__niter_base(__first2));
1066     }
1067 
1068   /**
1069    *  @brief Tests a range for element-wise equality.
1070    *  @ingroup non_mutating_algorithms
1071    *  @param  __first1  An input iterator.
1072    *  @param  __last1   An input iterator.
1073    *  @param  __first2  An input iterator.
1074    *  @param __binary_pred A binary predicate @link functors
1075    *                  functor@endlink.
1076    *  @return         A boolean true or false.
1077    *
1078    *  This compares the elements of two ranges using the binary_pred
1079    *  parameter, and returns true or
1080    *  false depending on whether all of the corresponding elements of the
1081    *  ranges are equal.
1082   */
1083   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1084     inline bool
1085     equal(_IIter1 __first1, _IIter1 __last1,
1086 	  _IIter2 __first2, _BinaryPredicate __binary_pred)
1087     {
1088       // concept requirements
1089       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1090       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1091       __glibcxx_requires_valid_range(__first1, __last1);
1092 
1093       for (; __first1 != __last1; ++__first1, ++__first2)
1094 	if (!bool(__binary_pred(*__first1, *__first2)))
1095 	  return false;
1096       return true;
1097     }
1098 
1099 #if __cplusplus > 201103L
1100 
1101 #define __cpp_lib_robust_nonmodifying_seq_ops 201304
1102 
1103   /**
1104    *  @brief Tests a range for element-wise equality.
1105    *  @ingroup non_mutating_algorithms
1106    *  @param  __first1  An input iterator.
1107    *  @param  __last1   An input iterator.
1108    *  @param  __first2  An input iterator.
1109    *  @param  __last2   An input iterator.
1110    *  @return   A boolean true or false.
1111    *
1112    *  This compares the elements of two ranges using @c == and returns true or
1113    *  false depending on whether all of the corresponding elements of the
1114    *  ranges are equal.
1115   */
1116   template<typename _II1, typename _II2>
1117     inline bool
1118     equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1119     {
1120       // concept requirements
1121       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1122       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1123       __glibcxx_function_requires(_EqualOpConcept<
1124 	    typename iterator_traits<_II1>::value_type,
1125 	    typename iterator_traits<_II2>::value_type>)
1126       __glibcxx_requires_valid_range(__first1, __last1);
1127       __glibcxx_requires_valid_range(__first2, __last2);
1128 
1129       using _RATag = random_access_iterator_tag;
1130       using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1131       using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1132       using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1133       if (_RAIters())
1134 	{
1135 	  auto __d1 = std::distance(__first1, __last1);
1136 	  auto __d2 = std::distance(__first2, __last2);
1137 	  if (__d1 != __d2)
1138 	    return false;
1139 	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1140 	}
1141 
1142       for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1143 	if (!(*__first1 == *__first2))
1144 	  return false;
1145       return __first1 == __last1 && __first2 == __last2;
1146     }
1147 
1148   /**
1149    *  @brief Tests a range for element-wise equality.
1150    *  @ingroup non_mutating_algorithms
1151    *  @param  __first1  An input iterator.
1152    *  @param  __last1   An input iterator.
1153    *  @param  __first2  An input iterator.
1154    *  @param  __last2   An input iterator.
1155    *  @param __binary_pred A binary predicate @link functors
1156    *                  functor@endlink.
1157    *  @return         A boolean true or false.
1158    *
1159    *  This compares the elements of two ranges using the binary_pred
1160    *  parameter, and returns true or
1161    *  false depending on whether all of the corresponding elements of the
1162    *  ranges are equal.
1163   */
1164   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1165     inline bool
1166     equal(_IIter1 __first1, _IIter1 __last1,
1167 	  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1168     {
1169       // concept requirements
1170       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1171       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1172       __glibcxx_requires_valid_range(__first1, __last1);
1173       __glibcxx_requires_valid_range(__first2, __last2);
1174 
1175       using _RATag = random_access_iterator_tag;
1176       using _Cat1 = typename iterator_traits<_IIter1>::iterator_category;
1177       using _Cat2 = typename iterator_traits<_IIter2>::iterator_category;
1178       using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1179       if (_RAIters())
1180 	{
1181 	  auto __d1 = std::distance(__first1, __last1);
1182 	  auto __d2 = std::distance(__first2, __last2);
1183 	  if (__d1 != __d2)
1184 	    return false;
1185 	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1186 				       __binary_pred);
1187 	}
1188 
1189       for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1190 	if (!bool(__binary_pred(*__first1, *__first2)))
1191 	  return false;
1192       return __first1 == __last1 && __first2 == __last2;
1193     }
1194 #endif
1195 
1196   /**
1197    *  @brief Performs @b dictionary comparison on ranges.
1198    *  @ingroup sorting_algorithms
1199    *  @param  __first1  An input iterator.
1200    *  @param  __last1   An input iterator.
1201    *  @param  __first2  An input iterator.
1202    *  @param  __last2   An input iterator.
1203    *  @return   A boolean true or false.
1204    *
1205    *  <em>Returns true if the sequence of elements defined by the range
1206    *  [first1,last1) is lexicographically less than the sequence of elements
1207    *  defined by the range [first2,last2).  Returns false otherwise.</em>
1208    *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
1209    *  then this is an inline call to @c memcmp.
1210   */
1211   template<typename _II1, typename _II2>
1212     inline bool
1213     lexicographical_compare(_II1 __first1, _II1 __last1,
1214 			    _II2 __first2, _II2 __last2)
1215     {
1216 #ifdef _GLIBCXX_CONCEPT_CHECKS
1217       // concept requirements
1218       typedef typename iterator_traits<_II1>::value_type _ValueType1;
1219       typedef typename iterator_traits<_II2>::value_type _ValueType2;
1220 #endif
1221       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1222       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1223       __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1224       __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1225       __glibcxx_requires_valid_range(__first1, __last1);
1226       __glibcxx_requires_valid_range(__first2, __last2);
1227 
1228       return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1229 						std::__niter_base(__last1),
1230 						std::__niter_base(__first2),
1231 						std::__niter_base(__last2));
1232     }
1233 
1234   /**
1235    *  @brief Performs @b dictionary comparison on ranges.
1236    *  @ingroup sorting_algorithms
1237    *  @param  __first1  An input iterator.
1238    *  @param  __last1   An input iterator.
1239    *  @param  __first2  An input iterator.
1240    *  @param  __last2   An input iterator.
1241    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
1242    *  @return   A boolean true or false.
1243    *
1244    *  The same as the four-parameter @c lexicographical_compare, but uses the
1245    *  comp parameter instead of @c <.
1246   */
1247   template<typename _II1, typename _II2, typename _Compare>
1248     inline bool
1249     lexicographical_compare(_II1 __first1, _II1 __last1,
1250 			    _II2 __first2, _II2 __last2, _Compare __comp)
1251     {
1252       // concept requirements
1253       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1254       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1255       __glibcxx_requires_valid_range(__first1, __last1);
1256       __glibcxx_requires_valid_range(__first2, __last2);
1257 
1258       return std::__lexicographical_compare_impl
1259 	(__first1, __last1, __first2, __last2,
1260 	 __gnu_cxx::__ops::__iter_comp_iter(__comp));
1261     }
1262 
1263   template<typename _InputIterator1, typename _InputIterator2,
1264 	   typename _BinaryPredicate>
1265     pair<_InputIterator1, _InputIterator2>
1266     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1267 	       _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1268     {
1269       while (__first1 != __last1 && __binary_pred(__first1, __first2))
1270         {
1271 	  ++__first1;
1272 	  ++__first2;
1273         }
1274       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1275     }
1276 
1277   /**
1278    *  @brief Finds the places in ranges which don't match.
1279    *  @ingroup non_mutating_algorithms
1280    *  @param  __first1  An input iterator.
1281    *  @param  __last1   An input iterator.
1282    *  @param  __first2  An input iterator.
1283    *  @return   A pair of iterators pointing to the first mismatch.
1284    *
1285    *  This compares the elements of two ranges using @c == and returns a pair
1286    *  of iterators.  The first iterator points into the first range, the
1287    *  second iterator points into the second range, and the elements pointed
1288    *  to by the iterators are not equal.
1289   */
1290   template<typename _InputIterator1, typename _InputIterator2>
1291     inline pair<_InputIterator1, _InputIterator2>
1292     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1293 	     _InputIterator2 __first2)
1294     {
1295       // concept requirements
1296       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1297       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1298       __glibcxx_function_requires(_EqualOpConcept<
1299 	    typename iterator_traits<_InputIterator1>::value_type,
1300 	    typename iterator_traits<_InputIterator2>::value_type>)
1301       __glibcxx_requires_valid_range(__first1, __last1);
1302 
1303       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1304 			     __gnu_cxx::__ops::__iter_equal_to_iter());
1305     }
1306 
1307   /**
1308    *  @brief Finds the places in ranges which don't match.
1309    *  @ingroup non_mutating_algorithms
1310    *  @param  __first1  An input iterator.
1311    *  @param  __last1   An input iterator.
1312    *  @param  __first2  An input iterator.
1313    *  @param __binary_pred A binary predicate @link functors
1314    *         functor@endlink.
1315    *  @return   A pair of iterators pointing to the first mismatch.
1316    *
1317    *  This compares the elements of two ranges using the binary_pred
1318    *  parameter, and returns a pair
1319    *  of iterators.  The first iterator points into the first range, the
1320    *  second iterator points into the second range, and the elements pointed
1321    *  to by the iterators are not equal.
1322   */
1323   template<typename _InputIterator1, typename _InputIterator2,
1324 	   typename _BinaryPredicate>
1325     inline pair<_InputIterator1, _InputIterator2>
1326     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1327 	     _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1328     {
1329       // concept requirements
1330       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1331       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1332       __glibcxx_requires_valid_range(__first1, __last1);
1333 
1334       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1335 	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1336     }
1337 
1338 #if __cplusplus > 201103L
1339 
1340   template<typename _InputIterator1, typename _InputIterator2,
1341 	   typename _BinaryPredicate>
1342     pair<_InputIterator1, _InputIterator2>
1343     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1344 	       _InputIterator2 __first2, _InputIterator2 __last2,
1345 	       _BinaryPredicate __binary_pred)
1346     {
1347       while (__first1 != __last1 && __first2 != __last2
1348 	     && __binary_pred(__first1, __first2))
1349         {
1350 	  ++__first1;
1351 	  ++__first2;
1352         }
1353       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1354     }
1355 
1356   /**
1357    *  @brief Finds the places in ranges which don't match.
1358    *  @ingroup non_mutating_algorithms
1359    *  @param  __first1  An input iterator.
1360    *  @param  __last1   An input iterator.
1361    *  @param  __first2  An input iterator.
1362    *  @param  __last2   An input iterator.
1363    *  @return   A pair of iterators pointing to the first mismatch.
1364    *
1365    *  This compares the elements of two ranges using @c == and returns a pair
1366    *  of iterators.  The first iterator points into the first range, the
1367    *  second iterator points into the second range, and the elements pointed
1368    *  to by the iterators are not equal.
1369   */
1370   template<typename _InputIterator1, typename _InputIterator2>
1371     inline pair<_InputIterator1, _InputIterator2>
1372     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1373 	     _InputIterator2 __first2, _InputIterator2 __last2)
1374     {
1375       // concept requirements
1376       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1377       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1378       __glibcxx_function_requires(_EqualOpConcept<
1379 	    typename iterator_traits<_InputIterator1>::value_type,
1380 	    typename iterator_traits<_InputIterator2>::value_type>)
1381       __glibcxx_requires_valid_range(__first1, __last1);
1382       __glibcxx_requires_valid_range(__first2, __last2);
1383 
1384       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1385 			     __gnu_cxx::__ops::__iter_equal_to_iter());
1386     }
1387 
1388   /**
1389    *  @brief Finds the places in ranges which don't match.
1390    *  @ingroup non_mutating_algorithms
1391    *  @param  __first1  An input iterator.
1392    *  @param  __last1   An input iterator.
1393    *  @param  __first2  An input iterator.
1394    *  @param  __last2   An input iterator.
1395    *  @param __binary_pred A binary predicate @link functors
1396    *         functor@endlink.
1397    *  @return   A pair of iterators pointing to the first mismatch.
1398    *
1399    *  This compares the elements of two ranges using the binary_pred
1400    *  parameter, and returns a pair
1401    *  of iterators.  The first iterator points into the first range, the
1402    *  second iterator points into the second range, and the elements pointed
1403    *  to by the iterators are not equal.
1404   */
1405   template<typename _InputIterator1, typename _InputIterator2,
1406 	   typename _BinaryPredicate>
1407     inline pair<_InputIterator1, _InputIterator2>
1408     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1409 	     _InputIterator2 __first2, _InputIterator2 __last2,
1410 	     _BinaryPredicate __binary_pred)
1411     {
1412       // concept requirements
1413       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1414       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1415       __glibcxx_requires_valid_range(__first1, __last1);
1416       __glibcxx_requires_valid_range(__first2, __last2);
1417 
1418       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1419 			     __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1420     }
1421 #endif
1422 
1423 _GLIBCXX_END_NAMESPACE_ALGO
1424 } // namespace std
1425 
1426 // NB: This file is included within many other C++ includes, as a way
1427 // of getting the base algorithms. So, make sure that parallel bits
1428 // come in too if requested.
1429 #ifdef _GLIBCXX_PARALLEL
1430 # include <parallel/algobase.h>
1431 #endif
1432 
1433 #endif
1434