1 // Core algorithmic facilities -*- C++ -*-
2 
3 // Copyright (C) 2001-2014 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 
_GLIBCXX_VISIBILITY(default)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     inline const _Tp&
194     min(const _Tp& __a, const _Tp& __b)
195     {
196       // concept requirements
197       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
198       //return __b < __a ? __b : __a;
199       if (__b < __a)
200 	return __b;
201       return __a;
202     }
203 
204   /**
205    *  @brief This does what you think it does.
206    *  @ingroup sorting_algorithms
207    *  @param  __a  A thing of arbitrary type.
208    *  @param  __b  Another thing of arbitrary type.
209    *  @return   The greater of the parameters.
210    *
211    *  This is the simple classic generic implementation.  It will work on
212    *  temporary expressions, since they are only evaluated once, unlike a
213    *  preprocessor macro.
214   */
215   template<typename _Tp>
216     inline const _Tp&
217     max(const _Tp& __a, const _Tp& __b)
218     {
219       // concept requirements
220       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
221       //return  __a < __b ? __b : __a;
222       if (__a < __b)
223 	return __b;
224       return __a;
225     }
226 
227   /**
228    *  @brief This does what you think it does.
229    *  @ingroup sorting_algorithms
230    *  @param  __a  A thing of arbitrary type.
231    *  @param  __b  Another thing of arbitrary type.
232    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
233    *  @return   The lesser of the parameters.
234    *
235    *  This will work on temporary expressions, since they are only evaluated
236    *  once, unlike a preprocessor macro.
237   */
238   template<typename _Tp, typename _Compare>
239     inline const _Tp&
240     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
241     {
242       //return __comp(__b, __a) ? __b : __a;
243       if (__comp(__b, __a))
244 	return __b;
245       return __a;
246     }
247 
248   /**
249    *  @brief This does what you think it does.
250    *  @ingroup sorting_algorithms
251    *  @param  __a  A thing of arbitrary type.
252    *  @param  __b  Another thing of arbitrary type.
253    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
254    *  @return   The greater of the parameters.
255    *
256    *  This will work on temporary expressions, since they are only evaluated
257    *  once, unlike a preprocessor macro.
258   */
259   template<typename _Tp, typename _Compare>
260     inline const _Tp&
261     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
262     {
263       //return __comp(__a, __b) ? __b : __a;
264       if (__comp(__a, __b))
265 	return __b;
266       return __a;
267     }
268 
269   // If _Iterator is a __normal_iterator return its base (a plain pointer,
270   // normally) otherwise return it untouched.  See copy, fill, ...
271   template<typename _Iterator>
272     struct _Niter_base
273     : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
274     { };
275 
276   template<typename _Iterator>
277     inline typename _Niter_base<_Iterator>::iterator_type
278     __niter_base(_Iterator __it)
279     { return std::_Niter_base<_Iterator>::_S_base(__it); }
280 
281   // Likewise, for move_iterator.
282   template<typename _Iterator>
283     struct _Miter_base
284     : _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
285     { };
286 
287   template<typename _Iterator>
288     inline typename _Miter_base<_Iterator>::iterator_type
289     __miter_base(_Iterator __it)
290     { return std::_Miter_base<_Iterator>::_S_base(__it); }
291 
292   // All of these auxiliary structs serve two purposes.  (1) Replace
293   // calls to copy with memmove whenever possible.  (Memmove, not memcpy,
294   // because the input and output ranges are permitted to overlap.)
295   // (2) If we're using random access iterators, then write the loop as
296   // a for loop with an explicit count.
297 
298   template<bool, bool, typename>
299     struct __copy_move
300     {
301       template<typename _II, typename _OI>
302         static _OI
303         __copy_m(_II __first, _II __last, _OI __result)
304         {
305 	  for (; __first != __last; ++__result, ++__first)
306 	    *__result = *__first;
307 	  return __result;
308 	}
309     };
310 
311 #if __cplusplus >= 201103L
312   template<typename _Category>
313     struct __copy_move<true, false, _Category>
314     {
315       template<typename _II, typename _OI>
316         static _OI
317         __copy_m(_II __first, _II __last, _OI __result)
318         {
319 	  for (; __first != __last; ++__result, ++__first)
320 	    *__result = std::move(*__first);
321 	  return __result;
322 	}
323     };
324 #endif
325 
326   template<>
327     struct __copy_move<false, false, random_access_iterator_tag>
328     {
329       template<typename _II, typename _OI>
330         static _OI
331         __copy_m(_II __first, _II __last, _OI __result)
332         {
333 	  typedef typename iterator_traits<_II>::difference_type _Distance;
334 	  for(_Distance __n = __last - __first; __n > 0; --__n)
335 	    {
336 	      *__result = *__first;
337 	      ++__first;
338 	      ++__result;
339 	    }
340 	  return __result;
341 	}
342     };
343 
344 #if __cplusplus >= 201103L
345   template<>
346     struct __copy_move<true, false, random_access_iterator_tag>
347     {
348       template<typename _II, typename _OI>
349         static _OI
350         __copy_m(_II __first, _II __last, _OI __result)
351         {
352 	  typedef typename iterator_traits<_II>::difference_type _Distance;
353 	  for(_Distance __n = __last - __first; __n > 0; --__n)
354 	    {
355 	      *__result = std::move(*__first);
356 	      ++__first;
357 	      ++__result;
358 	    }
359 	  return __result;
360 	}
361     };
362 #endif
363 
364   template<bool _IsMove>
365     struct __copy_move<_IsMove, true, random_access_iterator_tag>
366     {
367       template<typename _Tp>
368         static _Tp*
369         __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
370         {
371 #if __cplusplus >= 201103L
372 	  // trivial types can have deleted assignment
373 	  static_assert( is_copy_assignable<_Tp>::value,
374 	                 "type is not assignable" );
375 #endif
376 	  const ptrdiff_t _Num = __last - __first;
377 	  if (_Num)
378 	    __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
379 	  return __result + _Num;
380 	}
381     };
382 
383   template<bool _IsMove, typename _II, typename _OI>
384     inline _OI
385     __copy_move_a(_II __first, _II __last, _OI __result)
386     {
387       typedef typename iterator_traits<_II>::value_type _ValueTypeI;
388       typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
389       typedef typename iterator_traits<_II>::iterator_category _Category;
390       const bool __simple = (__is_trivial(_ValueTypeI)
391 	                     && __is_pointer<_II>::__value
392 	                     && __is_pointer<_OI>::__value
393 			     && __are_same<_ValueTypeI, _ValueTypeO>::__value);
394 
395       return std::__copy_move<_IsMove, __simple,
396 	                      _Category>::__copy_m(__first, __last, __result);
397     }
398 
399   // Helpers for streambuf iterators (either istream or ostream).
400   // NB: avoid including <iosfwd>, relatively large.
401   template<typename _CharT>
402     struct char_traits;
403 
404   template<typename _CharT, typename _Traits>
405     class istreambuf_iterator;
406 
407   template<typename _CharT, typename _Traits>
408     class ostreambuf_iterator;
409 
410   template<bool _IsMove, typename _CharT>
411     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
412 	     ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
413     __copy_move_a2(_CharT*, _CharT*,
414 		   ostreambuf_iterator<_CharT, char_traits<_CharT> >);
415 
416   template<bool _IsMove, typename _CharT>
417     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
418 	     ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
419     __copy_move_a2(const _CharT*, const _CharT*,
420 		   ostreambuf_iterator<_CharT, char_traits<_CharT> >);
421 
422   template<bool _IsMove, typename _CharT>
423     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
424 				    _CharT*>::__type
425     __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
426 		   istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
427 
428   template<bool _IsMove, typename _II, typename _OI>
429     inline _OI
430     __copy_move_a2(_II __first, _II __last, _OI __result)
431     {
432       return _OI(std::__copy_move_a<_IsMove>(std::__niter_base(__first),
433 					     std::__niter_base(__last),
434 					     std::__niter_base(__result)));
435     }
436 
437   /**
438    *  @brief Copies the range [first,last) into result.
439    *  @ingroup mutating_algorithms
440    *  @param  __first  An input iterator.
441    *  @param  __last   An input iterator.
442    *  @param  __result An output iterator.
443    *  @return   result + (first - last)
444    *
445    *  This inline function will boil down to a call to @c memmove whenever
446    *  possible.  Failing that, if random access iterators are passed, then the
447    *  loop count will be known (and therefore a candidate for compiler
448    *  optimizations such as unrolling).  Result may not be contained within
449    *  [first,last); the copy_backward function should be used instead.
450    *
451    *  Note that the end of the output range is permitted to be contained
452    *  within [first,last).
453   */
454   template<typename _II, typename _OI>
455     inline _OI
456     copy(_II __first, _II __last, _OI __result)
457     {
458       // concept requirements
459       __glibcxx_function_requires(_InputIteratorConcept<_II>)
460       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
461 	    typename iterator_traits<_II>::value_type>)
462       __glibcxx_requires_valid_range(__first, __last);
463 
464       return (std::__copy_move_a2<__is_move_iterator<_II>::__value>
465 	      (std::__miter_base(__first), std::__miter_base(__last),
466 	       __result));
467     }
468 
469 #if __cplusplus >= 201103L
470   /**
471    *  @brief Moves the range [first,last) into result.
472    *  @ingroup mutating_algorithms
473    *  @param  __first  An input iterator.
474    *  @param  __last   An input iterator.
475    *  @param  __result An output iterator.
476    *  @return   result + (first - last)
477    *
478    *  This inline function will boil down to a call to @c memmove whenever
479    *  possible.  Failing that, if random access iterators are passed, then the
480    *  loop count will be known (and therefore a candidate for compiler
481    *  optimizations such as unrolling).  Result may not be contained within
482    *  [first,last); the move_backward function should be used instead.
483    *
484    *  Note that the end of the output range is permitted to be contained
485    *  within [first,last).
486   */
487   template<typename _II, typename _OI>
488     inline _OI
489     move(_II __first, _II __last, _OI __result)
490     {
491       // concept requirements
492       __glibcxx_function_requires(_InputIteratorConcept<_II>)
493       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
494 	    typename iterator_traits<_II>::value_type>)
495       __glibcxx_requires_valid_range(__first, __last);
496 
497       return std::__copy_move_a2<true>(std::__miter_base(__first),
498 				       std::__miter_base(__last), __result);
499     }
500 
501 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
502 #else
503 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
504 #endif
505 
506   template<bool, bool, typename>
507     struct __copy_move_backward
508     {
509       template<typename _BI1, typename _BI2>
510         static _BI2
511         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
512         {
513 	  while (__first != __last)
514 	    *--__result = *--__last;
515 	  return __result;
516 	}
517     };
518 
519 #if __cplusplus >= 201103L
520   template<typename _Category>
521     struct __copy_move_backward<true, false, _Category>
522     {
523       template<typename _BI1, typename _BI2>
524         static _BI2
525         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
526         {
527 	  while (__first != __last)
528 	    *--__result = std::move(*--__last);
529 	  return __result;
530 	}
531     };
532 #endif
533 
534   template<>
535     struct __copy_move_backward<false, false, random_access_iterator_tag>
536     {
537       template<typename _BI1, typename _BI2>
538         static _BI2
539         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
540         {
541 	  typename iterator_traits<_BI1>::difference_type __n;
542 	  for (__n = __last - __first; __n > 0; --__n)
543 	    *--__result = *--__last;
544 	  return __result;
545 	}
546     };
547 
548 #if __cplusplus >= 201103L
549   template<>
550     struct __copy_move_backward<true, false, random_access_iterator_tag>
551     {
552       template<typename _BI1, typename _BI2>
553         static _BI2
554         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
555         {
556 	  typename iterator_traits<_BI1>::difference_type __n;
557 	  for (__n = __last - __first; __n > 0; --__n)
558 	    *--__result = std::move(*--__last);
559 	  return __result;
560 	}
561     };
562 #endif
563 
564   template<bool _IsMove>
565     struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
566     {
567       template<typename _Tp>
568         static _Tp*
569         __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
570         {
571 #if __cplusplus >= 201103L
572 	  // trivial types can have deleted assignment
573 	  static_assert( is_copy_assignable<_Tp>::value,
574 	                 "type is not assignable" );
575 #endif
576 	  const ptrdiff_t _Num = __last - __first;
577 	  if (_Num)
578 	    __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
579 	  return __result - _Num;
580 	}
581     };
582 
583   template<bool _IsMove, typename _BI1, typename _BI2>
584     inline _BI2
585     __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
586     {
587       typedef typename iterator_traits<_BI1>::value_type _ValueType1;
588       typedef typename iterator_traits<_BI2>::value_type _ValueType2;
589       typedef typename iterator_traits<_BI1>::iterator_category _Category;
590       const bool __simple = (__is_trivial(_ValueType1)
591 	                     && __is_pointer<_BI1>::__value
592 	                     && __is_pointer<_BI2>::__value
593 			     && __are_same<_ValueType1, _ValueType2>::__value);
594 
595       return std::__copy_move_backward<_IsMove, __simple,
596 	                               _Category>::__copy_move_b(__first,
597 								 __last,
598 								 __result);
599     }
600 
601   template<bool _IsMove, typename _BI1, typename _BI2>
602     inline _BI2
603     __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
604     {
605       return _BI2(std::__copy_move_backward_a<_IsMove>
606 		  (std::__niter_base(__first), std::__niter_base(__last),
607 		   std::__niter_base(__result)));
608     }
609 
610   /**
611    *  @brief Copies the range [first,last) into result.
612    *  @ingroup mutating_algorithms
613    *  @param  __first  A bidirectional iterator.
614    *  @param  __last   A bidirectional iterator.
615    *  @param  __result A bidirectional iterator.
616    *  @return   result - (first - last)
617    *
618    *  The function has the same effect as copy, but starts at the end of the
619    *  range and works its way to the start, returning the start of the result.
620    *  This inline function will boil down to a call to @c memmove whenever
621    *  possible.  Failing that, if random access iterators are passed, then the
622    *  loop count will be known (and therefore a candidate for compiler
623    *  optimizations such as unrolling).
624    *
625    *  Result may not be in the range (first,last].  Use copy instead.  Note
626    *  that the start of the output range may overlap [first,last).
627   */
628   template<typename _BI1, typename _BI2>
629     inline _BI2
630     copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
631     {
632       // concept requirements
633       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
634       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
635       __glibcxx_function_requires(_ConvertibleConcept<
636 	    typename iterator_traits<_BI1>::value_type,
637 	    typename iterator_traits<_BI2>::value_type>)
638       __glibcxx_requires_valid_range(__first, __last);
639 
640       return (std::__copy_move_backward_a2<__is_move_iterator<_BI1>::__value>
641 	      (std::__miter_base(__first), std::__miter_base(__last),
642 	       __result));
643     }
644 
645 #if __cplusplus >= 201103L
646   /**
647    *  @brief Moves the range [first,last) into result.
648    *  @ingroup mutating_algorithms
649    *  @param  __first  A bidirectional iterator.
650    *  @param  __last   A bidirectional iterator.
651    *  @param  __result A bidirectional iterator.
652    *  @return   result - (first - last)
653    *
654    *  The function has the same effect as move, but starts at the end of the
655    *  range and works its way to the start, returning the start of the result.
656    *  This inline function will boil down to a call to @c memmove whenever
657    *  possible.  Failing that, if random access iterators are passed, then the
658    *  loop count will be known (and therefore a candidate for compiler
659    *  optimizations such as unrolling).
660    *
661    *  Result may not be in the range (first,last].  Use move instead.  Note
662    *  that the start of the output range may overlap [first,last).
663   */
664   template<typename _BI1, typename _BI2>
665     inline _BI2
666     move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
667     {
668       // concept requirements
669       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
670       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
671       __glibcxx_function_requires(_ConvertibleConcept<
672 	    typename iterator_traits<_BI1>::value_type,
673 	    typename iterator_traits<_BI2>::value_type>)
674       __glibcxx_requires_valid_range(__first, __last);
675 
676       return std::__copy_move_backward_a2<true>(std::__miter_base(__first),
677 						std::__miter_base(__last),
678 						__result);
679     }
680 
681 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
682 #else
683 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
684 #endif
685 
686   template<typename _ForwardIterator, typename _Tp>
687     inline typename
688     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
689     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
690  	     const _Tp& __value)
691     {
692       for (; __first != __last; ++__first)
693 	*__first = __value;
694     }
695 
696   template<typename _ForwardIterator, typename _Tp>
697     inline typename
698     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
699     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
700 	     const _Tp& __value)
701     {
702       const _Tp __tmp = __value;
703       for (; __first != __last; ++__first)
704 	*__first = __tmp;
705     }
706 
707   // Specialization: for char types we can use memset.
708   template<typename _Tp>
709     inline typename
710     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
711     __fill_a(_Tp* __first, _Tp* __last, const _Tp& __c)
712     {
713       const _Tp __tmp = __c;
714       if (const size_t __len = __last - __first)
715 	__builtin_memset(__first, static_cast<unsigned char>(__tmp), __len);
716     }
717 
718   /**
719    *  @brief Fills the range [first,last) with copies of value.
720    *  @ingroup mutating_algorithms
721    *  @param  __first  A forward iterator.
722    *  @param  __last   A forward iterator.
723    *  @param  __value  A reference-to-const of arbitrary type.
724    *  @return   Nothing.
725    *
726    *  This function fills a range with copies of the same value.  For char
727    *  types filling contiguous areas of memory, this becomes an inline call
728    *  to @c memset or @c wmemset.
729   */
730   template<typename _ForwardIterator, typename _Tp>
731     inline void
732     fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
733     {
734       // concept requirements
735       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
736 				  _ForwardIterator>)
737       __glibcxx_requires_valid_range(__first, __last);
738 
739       std::__fill_a(std::__niter_base(__first), std::__niter_base(__last),
740 		    __value);
741     }
742 
743   template<typename _OutputIterator, typename _Size, typename _Tp>
744     inline typename
745     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
746     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
747     {
748       for (__decltype(__n + 0) __niter = __n;
749 	   __niter > 0; --__niter, ++__first)
750 	*__first = __value;
751       return __first;
752     }
753 
754   template<typename _OutputIterator, typename _Size, typename _Tp>
755     inline typename
756     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
757     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
758     {
759       const _Tp __tmp = __value;
760       for (__decltype(__n + 0) __niter = __n;
761 	   __niter > 0; --__niter, ++__first)
762 	*__first = __tmp;
763       return __first;
764     }
765 
766   template<typename _Size, typename _Tp>
767     inline typename
768     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, _Tp*>::__type
769     __fill_n_a(_Tp* __first, _Size __n, const _Tp& __c)
770     {
771       std::__fill_a(__first, __first + __n, __c);
772       return __first + __n;
773     }
774 
775   /**
776    *  @brief Fills the range [first,first+n) with copies of value.
777    *  @ingroup mutating_algorithms
778    *  @param  __first  An output iterator.
779    *  @param  __n      The count of copies to perform.
780    *  @param  __value  A reference-to-const of arbitrary type.
781    *  @return   The iterator at first+n.
782    *
783    *  This function fills a range with copies of the same value.  For char
784    *  types filling contiguous areas of memory, this becomes an inline call
785    *  to @c memset or @ wmemset.
786    *
787    *  _GLIBCXX_RESOLVE_LIB_DEFECTS
788    *  DR 865. More algorithms that throw away information
789   */
790   template<typename _OI, typename _Size, typename _Tp>
791     inline _OI
792     fill_n(_OI __first, _Size __n, const _Tp& __value)
793     {
794       // concept requirements
795       __glibcxx_function_requires(_OutputIteratorConcept<_OI, _Tp>)
796 
797       return _OI(std::__fill_n_a(std::__niter_base(__first), __n, __value));
798     }
799 
800   template<bool _BoolType>
801     struct __equal
802     {
803       template<typename _II1, typename _II2>
804         static bool
805         equal(_II1 __first1, _II1 __last1, _II2 __first2)
806         {
807 	  for (; __first1 != __last1; ++__first1, ++__first2)
808 	    if (!(*__first1 == *__first2))
809 	      return false;
810 	  return true;
811 	}
812     };
813 
814   template<>
815     struct __equal<true>
816     {
817       template<typename _Tp>
818         static bool
819         equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
820         {
821 	  if (const size_t __len = (__last1 - __first1))
822 	    return !__builtin_memcmp(__first1, __first2, sizeof(_Tp) * __len);
823 	  return true;
824 	}
825     };
826 
827   template<typename _II1, typename _II2>
828     inline bool
829     __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
830     {
831       typedef typename iterator_traits<_II1>::value_type _ValueType1;
832       typedef typename iterator_traits<_II2>::value_type _ValueType2;
833       const bool __simple = ((__is_integer<_ValueType1>::__value
834 			      || __is_pointer<_ValueType1>::__value)
835 	                     && __is_pointer<_II1>::__value
836 	                     && __is_pointer<_II2>::__value
837 			     && __are_same<_ValueType1, _ValueType2>::__value);
838 
839       return std::__equal<__simple>::equal(__first1, __last1, __first2);
840     }
841 
842   template<typename, typename>
843     struct __lc_rai
844     {
845       template<typename _II1, typename _II2>
846         static _II1
847         __newlast1(_II1, _II1 __last1, _II2, _II2)
848         { return __last1; }
849 
850       template<typename _II>
851         static bool
852         __cnd2(_II __first, _II __last)
853         { return __first != __last; }
854     };
855 
856   template<>
857     struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
858     {
859       template<typename _RAI1, typename _RAI2>
860         static _RAI1
861         __newlast1(_RAI1 __first1, _RAI1 __last1,
862 		   _RAI2 __first2, _RAI2 __last2)
863         {
864 	  const typename iterator_traits<_RAI1>::difference_type
865 	    __diff1 = __last1 - __first1;
866 	  const typename iterator_traits<_RAI2>::difference_type
867 	    __diff2 = __last2 - __first2;
868 	  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
869 	}
870 
871       template<typename _RAI>
872         static bool
873         __cnd2(_RAI, _RAI)
874         { return true; }
875     };
876 
877   template<typename _II1, typename _II2, typename _Compare>
878     bool
879     __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
880 				   _II2 __first2, _II2 __last2,
881 				   _Compare __comp)
882     {
883       typedef typename iterator_traits<_II1>::iterator_category _Category1;
884       typedef typename iterator_traits<_II2>::iterator_category _Category2;
885       typedef std::__lc_rai<_Category1, _Category2> __rai_type;
886 
887       __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
888       for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
889 	   ++__first1, ++__first2)
890 	{
891 	  if (__comp(__first1, __first2))
892 	    return true;
893 	  if (__comp(__first2, __first1))
894 	    return false;
895 	}
896       return __first1 == __last1 && __first2 != __last2;
897     }
898 
899   template<bool _BoolType>
900     struct __lexicographical_compare
901     {
902       template<typename _II1, typename _II2>
903         static bool __lc(_II1, _II1, _II2, _II2);
904     };
905 
906   template<bool _BoolType>
907     template<typename _II1, typename _II2>
908       bool
909       __lexicographical_compare<_BoolType>::
910       __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
911       {
912 	return std::__lexicographical_compare_impl(__first1, __last1,
913 						   __first2, __last2,
914 					__gnu_cxx::__ops::__iter_less_iter());
915       }
916 
917   template<>
918     struct __lexicographical_compare<true>
919     {
920       template<typename _Tp, typename _Up>
921         static bool
922         __lc(const _Tp* __first1, const _Tp* __last1,
923 	     const _Up* __first2, const _Up* __last2)
924 	{
925 	  const size_t __len1 = __last1 - __first1;
926 	  const size_t __len2 = __last2 - __first2;
927 	  if (const size_t __len = std::min(__len1, __len2))
928 	    if (int __result = __builtin_memcmp(__first1, __first2, __len))
929 	      return __result < 0;
930 	  return __len1 < __len2;
931 	}
932     };
933 
934   template<typename _II1, typename _II2>
935     inline bool
936     __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
937 				  _II2 __first2, _II2 __last2)
938     {
939       typedef typename iterator_traits<_II1>::value_type _ValueType1;
940       typedef typename iterator_traits<_II2>::value_type _ValueType2;
941       const bool __simple =
942 	(__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
943 	 && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
944 	 && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
945 	 && __is_pointer<_II1>::__value
946 	 && __is_pointer<_II2>::__value);
947 
948       return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
949 							    __first2, __last2);
950     }
951 
952   template<typename _ForwardIterator, typename _Tp, typename _Compare>
953     _ForwardIterator
954     __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
955 		  const _Tp& __val, _Compare __comp)
956     {
957       typedef typename iterator_traits<_ForwardIterator>::difference_type
958 	_DistanceType;
959 
960       _DistanceType __len = std::distance(__first, __last);
961 
962       while (__len > 0)
963 	{
964 	  _DistanceType __half = __len >> 1;
965 	  _ForwardIterator __middle = __first;
966 	  std::advance(__middle, __half);
967 	  if (__comp(__middle, __val))
968 	    {
969 	      __first = __middle;
970 	      ++__first;
971 	      __len = __len - __half - 1;
972 	    }
973 	  else
974 	    __len = __half;
975 	}
976       return __first;
977     }
978 
979   /**
980    *  @brief Finds the first position in which @a val could be inserted
981    *         without changing the ordering.
982    *  @param  __first   An iterator.
983    *  @param  __last    Another iterator.
984    *  @param  __val     The search term.
985    *  @return         An iterator pointing to the first element <em>not less
986    *                  than</em> @a val, or end() if every element is less than
987    *                  @a val.
988    *  @ingroup binary_search_algorithms
989   */
990   template<typename _ForwardIterator, typename _Tp>
991     inline _ForwardIterator
992     lower_bound(_ForwardIterator __first, _ForwardIterator __last,
993 		const _Tp& __val)
994     {
995       // concept requirements
996       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
997       __glibcxx_function_requires(_LessThanOpConcept<
998 	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
999       __glibcxx_requires_partitioned_lower(__first, __last, __val);
1000 
1001       return std::__lower_bound(__first, __last, __val,
1002 				__gnu_cxx::__ops::__iter_less_val());
1003     }
1004 
1005   /// This is a helper function for the sort routines and for random.tcc.
1006   //  Precondition: __n > 0.
1007   inline _GLIBCXX_CONSTEXPR int
1008   __lg(int __n)
1009   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1010 
1011   inline _GLIBCXX_CONSTEXPR unsigned
1012   __lg(unsigned __n)
1013   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1014 
1015   inline _GLIBCXX_CONSTEXPR long
1016   __lg(long __n)
1017   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1018 
1019   inline _GLIBCXX_CONSTEXPR unsigned long
1020   __lg(unsigned long __n)
1021   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1022 
1023   inline _GLIBCXX_CONSTEXPR long long
1024   __lg(long long __n)
1025   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1026 
1027   inline _GLIBCXX_CONSTEXPR unsigned long long
1028   __lg(unsigned long long __n)
1029   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1030 
1031 _GLIBCXX_END_NAMESPACE_VERSION
1032 
1033 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1034 
1035   /**
1036    *  @brief Tests a range for element-wise equality.
1037    *  @ingroup non_mutating_algorithms
1038    *  @param  __first1  An input iterator.
1039    *  @param  __last1   An input iterator.
1040    *  @param  __first2  An input iterator.
1041    *  @return   A boolean true or false.
1042    *
1043    *  This compares the elements of two ranges using @c == and returns true or
1044    *  false depending on whether all of the corresponding elements of the
1045    *  ranges are equal.
1046   */
1047   template<typename _II1, typename _II2>
1048     inline bool
1049     equal(_II1 __first1, _II1 __last1, _II2 __first2)
1050     {
1051       // concept requirements
1052       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1053       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1054       __glibcxx_function_requires(_EqualOpConcept<
1055 	    typename iterator_traits<_II1>::value_type,
1056 	    typename iterator_traits<_II2>::value_type>)
1057       __glibcxx_requires_valid_range(__first1, __last1);
1058 
1059       return std::__equal_aux(std::__niter_base(__first1),
1060 			      std::__niter_base(__last1),
1061 			      std::__niter_base(__first2));
1062     }
1063 
1064   /**
1065    *  @brief Tests a range for element-wise equality.
1066    *  @ingroup non_mutating_algorithms
1067    *  @param  __first1  An input iterator.
1068    *  @param  __last1   An input iterator.
1069    *  @param  __first2  An input iterator.
1070    *  @param __binary_pred A binary predicate @link functors
1071    *                  functor@endlink.
1072    *  @return         A boolean true or false.
1073    *
1074    *  This compares the elements of two ranges using the binary_pred
1075    *  parameter, and returns true or
1076    *  false depending on whether all of the corresponding elements of the
1077    *  ranges are equal.
1078   */
1079   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1080     inline bool
1081     equal(_IIter1 __first1, _IIter1 __last1,
1082 	  _IIter2 __first2, _BinaryPredicate __binary_pred)
1083     {
1084       // concept requirements
1085       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1086       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1087       __glibcxx_requires_valid_range(__first1, __last1);
1088 
1089       for (; __first1 != __last1; ++__first1, ++__first2)
1090 	if (!bool(__binary_pred(*__first1, *__first2)))
1091 	  return false;
1092       return true;
1093     }
1094 
1095 #if __cplusplus > 201103L
1096 
1097 #define __cpp_lib_robust_nonmodifying_seq_ops 201304
1098 
1099   /**
1100    *  @brief Tests a range for element-wise equality.
1101    *  @ingroup non_mutating_algorithms
1102    *  @param  __first1  An input iterator.
1103    *  @param  __last1   An input iterator.
1104    *  @param  __first2  An input iterator.
1105    *  @param  __last2   An input iterator.
1106    *  @return   A boolean true or false.
1107    *
1108    *  This compares the elements of two ranges using @c == and returns true or
1109    *  false depending on whether all of the corresponding elements of the
1110    *  ranges are equal.
1111   */
1112   template<typename _II1, typename _II2>
1113     inline bool
1114     equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1115     {
1116       // concept requirements
1117       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1118       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1119       __glibcxx_function_requires(_EqualOpConcept<
1120 	    typename iterator_traits<_II1>::value_type,
1121 	    typename iterator_traits<_II2>::value_type>)
1122       __glibcxx_requires_valid_range(__first1, __last1);
1123       __glibcxx_requires_valid_range(__first2, __last2);
1124 
1125       using _RATag = random_access_iterator_tag;
1126       using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1127       using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1128       using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1129       if (_RAIters())
1130 	{
1131 	  auto __d1 = std::distance(__first1, __last1);
1132 	  auto __d2 = std::distance(__first2, __last2);
1133 	  if (__d1 != __d2)
1134 	    return false;
1135 	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1136 	}
1137 
1138       for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1139 	if (!(*__first1 == *__first2))
1140 	  return false;
1141       return __first1 == __last1 && __first2 == __last2;
1142     }
1143 
1144   /**
1145    *  @brief Tests a range for element-wise equality.
1146    *  @ingroup non_mutating_algorithms
1147    *  @param  __first1  An input iterator.
1148    *  @param  __last1   An input iterator.
1149    *  @param  __first2  An input iterator.
1150    *  @param  __last2   An input iterator.
1151    *  @param __binary_pred A binary predicate @link functors
1152    *                  functor@endlink.
1153    *  @return         A boolean true or false.
1154    *
1155    *  This compares the elements of two ranges using the binary_pred
1156    *  parameter, and returns true or
1157    *  false depending on whether all of the corresponding elements of the
1158    *  ranges are equal.
1159   */
1160   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1161     inline bool
1162     equal(_IIter1 __first1, _IIter1 __last1,
1163 	  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1164     {
1165       // concept requirements
1166       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1167       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1168       __glibcxx_requires_valid_range(__first1, __last1);
1169       __glibcxx_requires_valid_range(__first2, __last2);
1170 
1171       using _RATag = random_access_iterator_tag;
1172       using _Cat1 = typename iterator_traits<_IIter1>::iterator_category;
1173       using _Cat2 = typename iterator_traits<_IIter2>::iterator_category;
1174       using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1175       if (_RAIters())
1176 	{
1177 	  auto __d1 = std::distance(__first1, __last1);
1178 	  auto __d2 = std::distance(__first2, __last2);
1179 	  if (__d1 != __d2)
1180 	    return false;
1181 	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1182 				       __binary_pred);
1183 	}
1184 
1185       for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1186 	if (!bool(__binary_pred(*__first1, *__first2)))
1187 	  return false;
1188       return __first1 == __last1 && __first2 == __last2;
1189     }
1190 #endif
1191 
1192   /**
1193    *  @brief Performs @b dictionary comparison on ranges.
1194    *  @ingroup sorting_algorithms
1195    *  @param  __first1  An input iterator.
1196    *  @param  __last1   An input iterator.
1197    *  @param  __first2  An input iterator.
1198    *  @param  __last2   An input iterator.
1199    *  @return   A boolean true or false.
1200    *
1201    *  <em>Returns true if the sequence of elements defined by the range
1202    *  [first1,last1) is lexicographically less than the sequence of elements
1203    *  defined by the range [first2,last2).  Returns false otherwise.</em>
1204    *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
1205    *  then this is an inline call to @c memcmp.
1206   */
1207   template<typename _II1, typename _II2>
1208     inline bool
1209     lexicographical_compare(_II1 __first1, _II1 __last1,
1210 			    _II2 __first2, _II2 __last2)
1211     {
1212 #ifdef _GLIBCXX_CONCEPT_CHECKS
1213       // concept requirements
1214       typedef typename iterator_traits<_II1>::value_type _ValueType1;
1215       typedef typename iterator_traits<_II2>::value_type _ValueType2;
1216 #endif
1217       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1218       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1219       __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1220       __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1221       __glibcxx_requires_valid_range(__first1, __last1);
1222       __glibcxx_requires_valid_range(__first2, __last2);
1223 
1224       return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1225 						std::__niter_base(__last1),
1226 						std::__niter_base(__first2),
1227 						std::__niter_base(__last2));
1228     }
1229 
1230   /**
1231    *  @brief Performs @b dictionary comparison on ranges.
1232    *  @ingroup sorting_algorithms
1233    *  @param  __first1  An input iterator.
1234    *  @param  __last1   An input iterator.
1235    *  @param  __first2  An input iterator.
1236    *  @param  __last2   An input iterator.
1237    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
1238    *  @return   A boolean true or false.
1239    *
1240    *  The same as the four-parameter @c lexicographical_compare, but uses the
1241    *  comp parameter instead of @c <.
1242   */
1243   template<typename _II1, typename _II2, typename _Compare>
1244     inline bool
1245     lexicographical_compare(_II1 __first1, _II1 __last1,
1246 			    _II2 __first2, _II2 __last2, _Compare __comp)
1247     {
1248       // concept requirements
1249       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1250       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1251       __glibcxx_requires_valid_range(__first1, __last1);
1252       __glibcxx_requires_valid_range(__first2, __last2);
1253 
1254       return std::__lexicographical_compare_impl
1255 	(__first1, __last1, __first2, __last2,
1256 	 __gnu_cxx::__ops::__iter_comp_iter(__comp));
1257     }
1258 
1259   template<typename _InputIterator1, typename _InputIterator2,
1260 	   typename _BinaryPredicate>
1261     pair<_InputIterator1, _InputIterator2>
1262     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1263 	       _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1264     {
1265       while (__first1 != __last1 && __binary_pred(__first1, __first2))
1266         {
1267 	  ++__first1;
1268 	  ++__first2;
1269         }
1270       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1271     }
1272 
1273   /**
1274    *  @brief Finds the places in ranges which don't match.
1275    *  @ingroup non_mutating_algorithms
1276    *  @param  __first1  An input iterator.
1277    *  @param  __last1   An input iterator.
1278    *  @param  __first2  An input iterator.
1279    *  @return   A pair of iterators pointing to the first mismatch.
1280    *
1281    *  This compares the elements of two ranges using @c == and returns a pair
1282    *  of iterators.  The first iterator points into the first range, the
1283    *  second iterator points into the second range, and the elements pointed
1284    *  to by the iterators are not equal.
1285   */
1286   template<typename _InputIterator1, typename _InputIterator2>
1287     inline pair<_InputIterator1, _InputIterator2>
1288     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1289 	     _InputIterator2 __first2)
1290     {
1291       // concept requirements
1292       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1293       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1294       __glibcxx_function_requires(_EqualOpConcept<
1295 	    typename iterator_traits<_InputIterator1>::value_type,
1296 	    typename iterator_traits<_InputIterator2>::value_type>)
1297       __glibcxx_requires_valid_range(__first1, __last1);
1298 
1299       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1300 			     __gnu_cxx::__ops::__iter_equal_to_iter());
1301     }
1302 
1303   /**
1304    *  @brief Finds the places in ranges which don't match.
1305    *  @ingroup non_mutating_algorithms
1306    *  @param  __first1  An input iterator.
1307    *  @param  __last1   An input iterator.
1308    *  @param  __first2  An input iterator.
1309    *  @param __binary_pred A binary predicate @link functors
1310    *         functor@endlink.
1311    *  @return   A pair of iterators pointing to the first mismatch.
1312    *
1313    *  This compares the elements of two ranges using the binary_pred
1314    *  parameter, and returns a pair
1315    *  of iterators.  The first iterator points into the first range, the
1316    *  second iterator points into the second range, and the elements pointed
1317    *  to by the iterators are not equal.
1318   */
1319   template<typename _InputIterator1, typename _InputIterator2,
1320 	   typename _BinaryPredicate>
1321     inline pair<_InputIterator1, _InputIterator2>
1322     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1323 	     _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1324     {
1325       // concept requirements
1326       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1327       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1328       __glibcxx_requires_valid_range(__first1, __last1);
1329 
1330       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1331 	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1332     }
1333 
1334 #if __cplusplus > 201103L
1335 
1336   template<typename _InputIterator1, typename _InputIterator2,
1337 	   typename _BinaryPredicate>
1338     pair<_InputIterator1, _InputIterator2>
1339     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1340 	       _InputIterator2 __first2, _InputIterator2 __last2,
1341 	       _BinaryPredicate __binary_pred)
1342     {
1343       while (__first1 != __last1 && __first2 != __last2
1344 	     && __binary_pred(__first1, __first2))
1345         {
1346 	  ++__first1;
1347 	  ++__first2;
1348         }
1349       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1350     }
1351 
1352   /**
1353    *  @brief Finds the places in ranges which don't match.
1354    *  @ingroup non_mutating_algorithms
1355    *  @param  __first1  An input iterator.
1356    *  @param  __last1   An input iterator.
1357    *  @param  __first2  An input iterator.
1358    *  @param  __last2   An input iterator.
1359    *  @return   A pair of iterators pointing to the first mismatch.
1360    *
1361    *  This compares the elements of two ranges using @c == and returns a pair
1362    *  of iterators.  The first iterator points into the first range, the
1363    *  second iterator points into the second range, and the elements pointed
1364    *  to by the iterators are not equal.
1365   */
1366   template<typename _InputIterator1, typename _InputIterator2>
1367     inline pair<_InputIterator1, _InputIterator2>
1368     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1369 	     _InputIterator2 __first2, _InputIterator2 __last2)
1370     {
1371       // concept requirements
1372       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1373       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1374       __glibcxx_function_requires(_EqualOpConcept<
1375 	    typename iterator_traits<_InputIterator1>::value_type,
1376 	    typename iterator_traits<_InputIterator2>::value_type>)
1377       __glibcxx_requires_valid_range(__first1, __last1);
1378       __glibcxx_requires_valid_range(__first2, __last2);
1379 
1380       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1381 			     __gnu_cxx::__ops::__iter_equal_to_iter());
1382     }
1383 
1384   /**
1385    *  @brief Finds the places in ranges which don't match.
1386    *  @ingroup non_mutating_algorithms
1387    *  @param  __first1  An input iterator.
1388    *  @param  __last1   An input iterator.
1389    *  @param  __first2  An input iterator.
1390    *  @param  __last2   An input iterator.
1391    *  @param __binary_pred A binary predicate @link functors
1392    *         functor@endlink.
1393    *  @return   A pair of iterators pointing to the first mismatch.
1394    *
1395    *  This compares the elements of two ranges using the binary_pred
1396    *  parameter, and returns a pair
1397    *  of iterators.  The first iterator points into the first range, the
1398    *  second iterator points into the second range, and the elements pointed
1399    *  to by the iterators are not equal.
1400   */
1401   template<typename _InputIterator1, typename _InputIterator2,
1402 	   typename _BinaryPredicate>
1403     inline pair<_InputIterator1, _InputIterator2>
1404     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1405 	     _InputIterator2 __first2, _InputIterator2 __last2,
1406 	     _BinaryPredicate __binary_pred)
1407     {
1408       // concept requirements
1409       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1410       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1411       __glibcxx_requires_valid_range(__first1, __last1);
1412       __glibcxx_requires_valid_range(__first2, __last2);
1413 
1414       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1415 			     __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1416     }
1417 #endif
1418 
1419 _GLIBCXX_END_NAMESPACE_ALGO
1420 } // namespace std
1421 
1422 // NB: This file is included within many other C++ includes, as a way
1423 // of getting the base algorithms. So, make sure that parallel bits
1424 // come in too if requested.
1425 #ifdef _GLIBCXX_PARALLEL
1426 # include <parallel/algobase.h>
1427 #endif
1428 
1429 #endif
1430