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
73namespace 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      __builtin_memset(__first, static_cast<unsigned char>(__tmp),
715		       __last - __first);
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	  return !__builtin_memcmp(__first1, __first2, sizeof(_Tp)
822				   * (__last1 - __first1));
823	}
824    };
825
826  template<typename _II1, typename _II2>
827    inline bool
828    __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
829    {
830      typedef typename iterator_traits<_II1>::value_type _ValueType1;
831      typedef typename iterator_traits<_II2>::value_type _ValueType2;
832      const bool __simple = ((__is_integer<_ValueType1>::__value
833			      || __is_pointer<_ValueType1>::__value)
834	                     && __is_pointer<_II1>::__value
835	                     && __is_pointer<_II2>::__value
836			     && __are_same<_ValueType1, _ValueType2>::__value);
837
838      return std::__equal<__simple>::equal(__first1, __last1, __first2);
839    }
840
841  template<typename, typename>
842    struct __lc_rai
843    {
844      template<typename _II1, typename _II2>
845        static _II1
846        __newlast1(_II1, _II1 __last1, _II2, _II2)
847        { return __last1; }
848
849      template<typename _II>
850        static bool
851        __cnd2(_II __first, _II __last)
852        { return __first != __last; }
853    };
854
855  template<>
856    struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
857    {
858      template<typename _RAI1, typename _RAI2>
859        static _RAI1
860        __newlast1(_RAI1 __first1, _RAI1 __last1,
861		   _RAI2 __first2, _RAI2 __last2)
862        {
863	  const typename iterator_traits<_RAI1>::difference_type
864	    __diff1 = __last1 - __first1;
865	  const typename iterator_traits<_RAI2>::difference_type
866	    __diff2 = __last2 - __first2;
867	  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
868	}
869
870      template<typename _RAI>
871        static bool
872        __cnd2(_RAI, _RAI)
873        { return true; }
874    };
875
876  template<typename _II1, typename _II2, typename _Compare>
877    bool
878    __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
879				   _II2 __first2, _II2 __last2,
880				   _Compare __comp)
881    {
882      typedef typename iterator_traits<_II1>::iterator_category _Category1;
883      typedef typename iterator_traits<_II2>::iterator_category _Category2;
884      typedef std::__lc_rai<_Category1, _Category2> __rai_type;
885
886      __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
887      for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
888	   ++__first1, ++__first2)
889	{
890	  if (__comp(__first1, __first2))
891	    return true;
892	  if (__comp(__first2, __first1))
893	    return false;
894	}
895      return __first1 == __last1 && __first2 != __last2;
896    }
897
898  template<bool _BoolType>
899    struct __lexicographical_compare
900    {
901      template<typename _II1, typename _II2>
902        static bool __lc(_II1, _II1, _II2, _II2);
903    };
904
905  template<bool _BoolType>
906    template<typename _II1, typename _II2>
907      bool
908      __lexicographical_compare<_BoolType>::
909      __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
910      {
911	return std::__lexicographical_compare_impl(__first1, __last1,
912						   __first2, __last2,
913					__gnu_cxx::__ops::__iter_less_iter());
914      }
915
916  template<>
917    struct __lexicographical_compare<true>
918    {
919      template<typename _Tp, typename _Up>
920        static bool
921        __lc(const _Tp* __first1, const _Tp* __last1,
922	     const _Up* __first2, const _Up* __last2)
923	{
924	  const size_t __len1 = __last1 - __first1;
925	  const size_t __len2 = __last2 - __first2;
926	  const int __result = __builtin_memcmp(__first1, __first2,
927						std::min(__len1, __len2));
928	  return __result != 0 ? __result < 0 : __len1 < __len2;
929	}
930    };
931
932  template<typename _II1, typename _II2>
933    inline bool
934    __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
935				  _II2 __first2, _II2 __last2)
936    {
937      typedef typename iterator_traits<_II1>::value_type _ValueType1;
938      typedef typename iterator_traits<_II2>::value_type _ValueType2;
939      const bool __simple =
940	(__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
941	 && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
942	 && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
943	 && __is_pointer<_II1>::__value
944	 && __is_pointer<_II2>::__value);
945
946      return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
947							    __first2, __last2);
948    }
949
950  template<typename _ForwardIterator, typename _Tp, typename _Compare>
951    _ForwardIterator
952    __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
953		  const _Tp& __val, _Compare __comp)
954    {
955      typedef typename iterator_traits<_ForwardIterator>::difference_type
956	_DistanceType;
957
958      _DistanceType __len = std::distance(__first, __last);
959
960      while (__len > 0)
961	{
962	  _DistanceType __half = __len >> 1;
963	  _ForwardIterator __middle = __first;
964	  std::advance(__middle, __half);
965	  if (__comp(__middle, __val))
966	    {
967	      __first = __middle;
968	      ++__first;
969	      __len = __len - __half - 1;
970	    }
971	  else
972	    __len = __half;
973	}
974      return __first;
975    }
976
977  /**
978   *  @brief Finds the first position in which @a val could be inserted
979   *         without changing the ordering.
980   *  @param  __first   An iterator.
981   *  @param  __last    Another iterator.
982   *  @param  __val     The search term.
983   *  @return         An iterator pointing to the first element <em>not less
984   *                  than</em> @a val, or end() if every element is less than
985   *                  @a val.
986   *  @ingroup binary_search_algorithms
987  */
988  template<typename _ForwardIterator, typename _Tp>
989    inline _ForwardIterator
990    lower_bound(_ForwardIterator __first, _ForwardIterator __last,
991		const _Tp& __val)
992    {
993      // concept requirements
994      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
995      __glibcxx_function_requires(_LessThanOpConcept<
996	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
997      __glibcxx_requires_partitioned_lower(__first, __last, __val);
998
999      return std::__lower_bound(__first, __last, __val,
1000				__gnu_cxx::__ops::__iter_less_val());
1001    }
1002
1003  /// This is a helper function for the sort routines and for random.tcc.
1004  //  Precondition: __n > 0.
1005  inline _GLIBCXX_CONSTEXPR int
1006  __lg(int __n)
1007  { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1008
1009  inline _GLIBCXX_CONSTEXPR unsigned
1010  __lg(unsigned __n)
1011  { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
1012
1013  inline _GLIBCXX_CONSTEXPR long
1014  __lg(long __n)
1015  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1016
1017  inline _GLIBCXX_CONSTEXPR unsigned long
1018  __lg(unsigned long __n)
1019  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
1020
1021  inline _GLIBCXX_CONSTEXPR long long
1022  __lg(long long __n)
1023  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1024
1025  inline _GLIBCXX_CONSTEXPR unsigned long long
1026  __lg(unsigned long long __n)
1027  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1028
1029_GLIBCXX_END_NAMESPACE_VERSION
1030
1031_GLIBCXX_BEGIN_NAMESPACE_ALGO
1032
1033  /**
1034   *  @brief Tests a range for element-wise equality.
1035   *  @ingroup non_mutating_algorithms
1036   *  @param  __first1  An input iterator.
1037   *  @param  __last1   An input iterator.
1038   *  @param  __first2  An input iterator.
1039   *  @return   A boolean true or false.
1040   *
1041   *  This compares the elements of two ranges using @c == and returns true or
1042   *  false depending on whether all of the corresponding elements of the
1043   *  ranges are equal.
1044  */
1045  template<typename _II1, typename _II2>
1046    inline bool
1047    equal(_II1 __first1, _II1 __last1, _II2 __first2)
1048    {
1049      // concept requirements
1050      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1051      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1052      __glibcxx_function_requires(_EqualOpConcept<
1053	    typename iterator_traits<_II1>::value_type,
1054	    typename iterator_traits<_II2>::value_type>)
1055      __glibcxx_requires_valid_range(__first1, __last1);
1056
1057      return std::__equal_aux(std::__niter_base(__first1),
1058			      std::__niter_base(__last1),
1059			      std::__niter_base(__first2));
1060    }
1061
1062  /**
1063   *  @brief Tests a range for element-wise equality.
1064   *  @ingroup non_mutating_algorithms
1065   *  @param  __first1  An input iterator.
1066   *  @param  __last1   An input iterator.
1067   *  @param  __first2  An input iterator.
1068   *  @param __binary_pred A binary predicate @link functors
1069   *                  functor@endlink.
1070   *  @return         A boolean true or false.
1071   *
1072   *  This compares the elements of two ranges using the binary_pred
1073   *  parameter, and returns true or
1074   *  false depending on whether all of the corresponding elements of the
1075   *  ranges are equal.
1076  */
1077  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1078    inline bool
1079    equal(_IIter1 __first1, _IIter1 __last1,
1080	  _IIter2 __first2, _BinaryPredicate __binary_pred)
1081    {
1082      // concept requirements
1083      __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1084      __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1085      __glibcxx_requires_valid_range(__first1, __last1);
1086
1087      for (; __first1 != __last1; ++__first1, ++__first2)
1088	if (!bool(__binary_pred(*__first1, *__first2)))
1089	  return false;
1090      return true;
1091    }
1092
1093#if __cplusplus > 201103L
1094  /**
1095   *  @brief Tests a range for element-wise equality.
1096   *  @ingroup non_mutating_algorithms
1097   *  @param  __first1  An input iterator.
1098   *  @param  __last1   An input iterator.
1099   *  @param  __first2  An input iterator.
1100   *  @param  __last2   An input iterator.
1101   *  @return   A boolean true or false.
1102   *
1103   *  This compares the elements of two ranges using @c == and returns true or
1104   *  false depending on whether all of the corresponding elements of the
1105   *  ranges are equal.
1106  */
1107  template<typename _II1, typename _II2>
1108    inline bool
1109    equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1110    {
1111      // concept requirements
1112      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1113      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1114      __glibcxx_function_requires(_EqualOpConcept<
1115	    typename iterator_traits<_II1>::value_type,
1116	    typename iterator_traits<_II2>::value_type>)
1117      __glibcxx_requires_valid_range(__first1, __last1);
1118      __glibcxx_requires_valid_range(__first2, __last2);
1119
1120      using _RATag = random_access_iterator_tag;
1121      using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1122      using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1123      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1124      if (_RAIters())
1125	{
1126	  auto __d1 = std::distance(__first1, __last1);
1127	  auto __d2 = std::distance(__first2, __last2);
1128	  if (__d1 != __d2)
1129	    return false;
1130	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2);
1131	}
1132
1133      for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1134	if (!(*__first1 == *__first2))
1135	  return false;
1136      return __first1 == __last1 && __first2 == __last2;
1137    }
1138
1139  /**
1140   *  @brief Tests a range for element-wise equality.
1141   *  @ingroup non_mutating_algorithms
1142   *  @param  __first1  An input iterator.
1143   *  @param  __last1   An input iterator.
1144   *  @param  __first2  An input iterator.
1145   *  @param  __last2   An input iterator.
1146   *  @param __binary_pred A binary predicate @link functors
1147   *                  functor@endlink.
1148   *  @return         A boolean true or false.
1149   *
1150   *  This compares the elements of two ranges using the binary_pred
1151   *  parameter, and returns true or
1152   *  false depending on whether all of the corresponding elements of the
1153   *  ranges are equal.
1154  */
1155  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1156    inline bool
1157    equal(_IIter1 __first1, _IIter1 __last1,
1158	  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1159    {
1160      // concept requirements
1161      __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1162      __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1163      __glibcxx_requires_valid_range(__first1, __last1);
1164      __glibcxx_requires_valid_range(__first2, __last2);
1165
1166      using _RATag = random_access_iterator_tag;
1167      using _Cat1 = typename iterator_traits<_IIter1>::iterator_category;
1168      using _Cat2 = typename iterator_traits<_IIter2>::iterator_category;
1169      using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1170      if (_RAIters())
1171	{
1172	  auto __d1 = std::distance(__first1, __last1);
1173	  auto __d2 = std::distance(__first2, __last2);
1174	  if (__d1 != __d2)
1175	    return false;
1176	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
1177				       __binary_pred);
1178	}
1179
1180      for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1181	if (!bool(__binary_pred(*__first1, *__first2)))
1182	  return false;
1183      return __first1 == __last1 && __first2 == __last2;
1184    }
1185#endif
1186
1187  /**
1188   *  @brief Performs @b dictionary comparison on ranges.
1189   *  @ingroup sorting_algorithms
1190   *  @param  __first1  An input iterator.
1191   *  @param  __last1   An input iterator.
1192   *  @param  __first2  An input iterator.
1193   *  @param  __last2   An input iterator.
1194   *  @return   A boolean true or false.
1195   *
1196   *  <em>Returns true if the sequence of elements defined by the range
1197   *  [first1,last1) is lexicographically less than the sequence of elements
1198   *  defined by the range [first2,last2).  Returns false otherwise.</em>
1199   *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
1200   *  then this is an inline call to @c memcmp.
1201  */
1202  template<typename _II1, typename _II2>
1203    inline bool
1204    lexicographical_compare(_II1 __first1, _II1 __last1,
1205			    _II2 __first2, _II2 __last2)
1206    {
1207#ifdef _GLIBCXX_CONCEPT_CHECKS
1208      // concept requirements
1209      typedef typename iterator_traits<_II1>::value_type _ValueType1;
1210      typedef typename iterator_traits<_II2>::value_type _ValueType2;
1211#endif
1212      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1213      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1214      __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1215      __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1216      __glibcxx_requires_valid_range(__first1, __last1);
1217      __glibcxx_requires_valid_range(__first2, __last2);
1218
1219      return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1220						std::__niter_base(__last1),
1221						std::__niter_base(__first2),
1222						std::__niter_base(__last2));
1223    }
1224
1225  /**
1226   *  @brief Performs @b dictionary comparison on ranges.
1227   *  @ingroup sorting_algorithms
1228   *  @param  __first1  An input iterator.
1229   *  @param  __last1   An input iterator.
1230   *  @param  __first2  An input iterator.
1231   *  @param  __last2   An input iterator.
1232   *  @param  __comp  A @link comparison_functors comparison functor@endlink.
1233   *  @return   A boolean true or false.
1234   *
1235   *  The same as the four-parameter @c lexicographical_compare, but uses the
1236   *  comp parameter instead of @c <.
1237  */
1238  template<typename _II1, typename _II2, typename _Compare>
1239    inline bool
1240    lexicographical_compare(_II1 __first1, _II1 __last1,
1241			    _II2 __first2, _II2 __last2, _Compare __comp)
1242    {
1243      // concept requirements
1244      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1245      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1246      __glibcxx_requires_valid_range(__first1, __last1);
1247      __glibcxx_requires_valid_range(__first2, __last2);
1248
1249      return std::__lexicographical_compare_impl
1250	(__first1, __last1, __first2, __last2,
1251	 __gnu_cxx::__ops::__iter_comp_iter(__comp));
1252    }
1253
1254  template<typename _InputIterator1, typename _InputIterator2,
1255	   typename _BinaryPredicate>
1256    pair<_InputIterator1, _InputIterator2>
1257    __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1258	       _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1259    {
1260      while (__first1 != __last1 && __binary_pred(__first1, __first2))
1261        {
1262	  ++__first1;
1263	  ++__first2;
1264        }
1265      return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1266    }
1267
1268  /**
1269   *  @brief Finds the places in ranges which don't match.
1270   *  @ingroup non_mutating_algorithms
1271   *  @param  __first1  An input iterator.
1272   *  @param  __last1   An input iterator.
1273   *  @param  __first2  An input iterator.
1274   *  @return   A pair of iterators pointing to the first mismatch.
1275   *
1276   *  This compares the elements of two ranges using @c == and returns a pair
1277   *  of iterators.  The first iterator points into the first range, the
1278   *  second iterator points into the second range, and the elements pointed
1279   *  to by the iterators are not equal.
1280  */
1281  template<typename _InputIterator1, typename _InputIterator2>
1282    inline pair<_InputIterator1, _InputIterator2>
1283    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1284	     _InputIterator2 __first2)
1285    {
1286      // concept requirements
1287      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1288      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1289      __glibcxx_function_requires(_EqualOpConcept<
1290	    typename iterator_traits<_InputIterator1>::value_type,
1291	    typename iterator_traits<_InputIterator2>::value_type>)
1292      __glibcxx_requires_valid_range(__first1, __last1);
1293
1294      return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1295			     __gnu_cxx::__ops::__iter_equal_to_iter());
1296    }
1297
1298  /**
1299   *  @brief Finds the places in ranges which don't match.
1300   *  @ingroup non_mutating_algorithms
1301   *  @param  __first1  An input iterator.
1302   *  @param  __last1   An input iterator.
1303   *  @param  __first2  An input iterator.
1304   *  @param __binary_pred A binary predicate @link functors
1305   *         functor@endlink.
1306   *  @return   A pair of iterators pointing to the first mismatch.
1307   *
1308   *  This compares the elements of two ranges using the binary_pred
1309   *  parameter, and returns a pair
1310   *  of iterators.  The first iterator points into the first range, the
1311   *  second iterator points into the second range, and the elements pointed
1312   *  to by the iterators are not equal.
1313  */
1314  template<typename _InputIterator1, typename _InputIterator2,
1315	   typename _BinaryPredicate>
1316    inline pair<_InputIterator1, _InputIterator2>
1317    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1318	     _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1319    {
1320      // concept requirements
1321      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1322      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1323      __glibcxx_requires_valid_range(__first1, __last1);
1324
1325      return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
1326	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1327    }
1328
1329#if __cplusplus > 201103L
1330
1331  template<typename _InputIterator1, typename _InputIterator2,
1332	   typename _BinaryPredicate>
1333    pair<_InputIterator1, _InputIterator2>
1334    __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1335	       _InputIterator2 __first2, _InputIterator2 __last2,
1336	       _BinaryPredicate __binary_pred)
1337    {
1338      while (__first1 != __last1 && __first2 != __last2
1339	     && __binary_pred(__first1, __first2))
1340        {
1341	  ++__first1;
1342	  ++__first2;
1343        }
1344      return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1345    }
1346
1347  /**
1348   *  @brief Finds the places in ranges which don't match.
1349   *  @ingroup non_mutating_algorithms
1350   *  @param  __first1  An input iterator.
1351   *  @param  __last1   An input iterator.
1352   *  @param  __first2  An input iterator.
1353   *  @param  __last2   An input iterator.
1354   *  @return   A pair of iterators pointing to the first mismatch.
1355   *
1356   *  This compares the elements of two ranges using @c == and returns a pair
1357   *  of iterators.  The first iterator points into the first range, the
1358   *  second iterator points into the second range, and the elements pointed
1359   *  to by the iterators are not equal.
1360  */
1361  template<typename _InputIterator1, typename _InputIterator2>
1362    inline pair<_InputIterator1, _InputIterator2>
1363    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1364	     _InputIterator2 __first2, _InputIterator2 __last2)
1365    {
1366      // concept requirements
1367      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1368      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1369      __glibcxx_function_requires(_EqualOpConcept<
1370	    typename iterator_traits<_InputIterator1>::value_type,
1371	    typename iterator_traits<_InputIterator2>::value_type>)
1372      __glibcxx_requires_valid_range(__first1, __last1);
1373      __glibcxx_requires_valid_range(__first2, __last2);
1374
1375      return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1376			     __gnu_cxx::__ops::__iter_equal_to_iter());
1377    }
1378
1379  /**
1380   *  @brief Finds the places in ranges which don't match.
1381   *  @ingroup non_mutating_algorithms
1382   *  @param  __first1  An input iterator.
1383   *  @param  __last1   An input iterator.
1384   *  @param  __first2  An input iterator.
1385   *  @param  __last2   An input iterator.
1386   *  @param __binary_pred A binary predicate @link functors
1387   *         functor@endlink.
1388   *  @return   A pair of iterators pointing to the first mismatch.
1389   *
1390   *  This compares the elements of two ranges using the binary_pred
1391   *  parameter, and returns a pair
1392   *  of iterators.  The first iterator points into the first range, the
1393   *  second iterator points into the second range, and the elements pointed
1394   *  to by the iterators are not equal.
1395  */
1396  template<typename _InputIterator1, typename _InputIterator2,
1397	   typename _BinaryPredicate>
1398    inline pair<_InputIterator1, _InputIterator2>
1399    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1400	     _InputIterator2 __first2, _InputIterator2 __last2,
1401	     _BinaryPredicate __binary_pred)
1402    {
1403      // concept requirements
1404      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1405      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1406      __glibcxx_requires_valid_range(__first1, __last1);
1407      __glibcxx_requires_valid_range(__first2, __last2);
1408
1409      return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
1410			     __gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
1411    }
1412#endif
1413
1414_GLIBCXX_END_NAMESPACE_ALGO
1415} // namespace std
1416
1417// NB: This file is included within many other C++ includes, as a way
1418// of getting the base algorithms. So, make sure that parallel bits
1419// come in too if requested.
1420#ifdef _GLIBCXX_PARALLEL
1421# include <parallel/algobase.h>
1422#endif
1423
1424#endif
1425