libstdc++
stl_algobase.h
Go to the documentation of this file.
1 // Core algorithmic facilities -*- C++ -*-
2 
3 // Copyright (C) 2001-2013 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>
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 
72 namespace std _GLIBCXX_VISIBILITY(default)
73 {
74 _GLIBCXX_BEGIN_NAMESPACE_VERSION
75 
76 #if __cplusplus < 201103L
77  // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
78  // nutshell, we are partially implementing the resolution of DR 187,
79  // when it's safe, i.e., the value_types are equal.
80  template<bool _BoolType>
81  struct __iter_swap
82  {
83  template<typename _ForwardIterator1, typename _ForwardIterator2>
84  static void
85  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
86  {
87  typedef typename iterator_traits<_ForwardIterator1>::value_type
88  _ValueType1;
89  _ValueType1 __tmp = _GLIBCXX_MOVE(*__a);
90  *__a = _GLIBCXX_MOVE(*__b);
91  *__b = _GLIBCXX_MOVE(__tmp);
92  }
93  };
94 
95  template<>
96  struct __iter_swap<true>
97  {
98  template<typename _ForwardIterator1, typename _ForwardIterator2>
99  static void
100  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
101  {
102  swap(*__a, *__b);
103  }
104  };
105 #endif
106 
107  /**
108  * @brief Swaps the contents of two iterators.
109  * @ingroup mutating_algorithms
110  * @param __a An iterator.
111  * @param __b Another iterator.
112  * @return Nothing.
113  *
114  * This function swaps the values pointed to by two iterators, not the
115  * iterators themselves.
116  */
117  template<typename _ForwardIterator1, typename _ForwardIterator2>
118  inline void
119  iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
120  {
121  // concept requirements
122  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
123  _ForwardIterator1>)
124  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
125  _ForwardIterator2>)
126 
127 #if __cplusplus < 201103L
128  typedef typename iterator_traits<_ForwardIterator1>::value_type
129  _ValueType1;
130  typedef typename iterator_traits<_ForwardIterator2>::value_type
131  _ValueType2;
132 
133  __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
134  _ValueType2>)
135  __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
136  _ValueType1>)
137 
138  typedef typename iterator_traits<_ForwardIterator1>::reference
139  _ReferenceType1;
140  typedef typename iterator_traits<_ForwardIterator2>::reference
141  _ReferenceType2;
142  std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
143  && __are_same<_ValueType1&, _ReferenceType1>::__value
144  && __are_same<_ValueType2&, _ReferenceType2>::__value>::
145  iter_swap(__a, __b);
146 #else
147  swap(*__a, *__b);
148 #endif
149  }
150 
151  /**
152  * @brief Swap the elements of two sequences.
153  * @ingroup mutating_algorithms
154  * @param __first1 A forward iterator.
155  * @param __last1 A forward iterator.
156  * @param __first2 A forward iterator.
157  * @return An iterator equal to @p first2+(last1-first1).
158  *
159  * Swaps each element in the range @p [first1,last1) with the
160  * corresponding element in the range @p [first2,(last1-first1)).
161  * The ranges must not overlap.
162  */
163  template<typename _ForwardIterator1, typename _ForwardIterator2>
164  _ForwardIterator2
165  swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
166  _ForwardIterator2 __first2)
167  {
168  // concept requirements
169  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
170  _ForwardIterator1>)
171  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
172  _ForwardIterator2>)
173  __glibcxx_requires_valid_range(__first1, __last1);
174 
175  for (; __first1 != __last1; ++__first1, ++__first2)
176  std::iter_swap(__first1, __first2);
177  return __first2;
178  }
179 
180  /**
181  * @brief This does what you think it does.
182  * @ingroup sorting_algorithms
183  * @param __a A thing of arbitrary type.
184  * @param __b Another thing of arbitrary type.
185  * @return The lesser of the parameters.
186  *
187  * This is the simple classic generic implementation. It will work on
188  * temporary expressions, since they are only evaluated once, unlike a
189  * preprocessor macro.
190  */
191  template<typename _Tp>
192  inline const _Tp&
193  min(const _Tp& __a, const _Tp& __b)
194  {
195  // concept requirements
196  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
197  //return __b < __a ? __b : __a;
198  if (__b < __a)
199  return __b;
200  return __a;
201  }
202 
203  /**
204  * @brief This does what you think it does.
205  * @ingroup sorting_algorithms
206  * @param __a A thing of arbitrary type.
207  * @param __b Another thing of arbitrary type.
208  * @return The greater of the parameters.
209  *
210  * This is the simple classic generic implementation. It will work on
211  * temporary expressions, since they are only evaluated once, unlike a
212  * preprocessor macro.
213  */
214  template<typename _Tp>
215  inline const _Tp&
216  max(const _Tp& __a, const _Tp& __b)
217  {
218  // concept requirements
219  __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
220  //return __a < __b ? __b : __a;
221  if (__a < __b)
222  return __b;
223  return __a;
224  }
225 
226  /**
227  * @brief This does what you think it does.
228  * @ingroup sorting_algorithms
229  * @param __a A thing of arbitrary type.
230  * @param __b Another thing of arbitrary type.
231  * @param __comp A @link comparison_functors comparison functor@endlink.
232  * @return The lesser of the parameters.
233  *
234  * This will work on temporary expressions, since they are only evaluated
235  * once, unlike a preprocessor macro.
236  */
237  template<typename _Tp, typename _Compare>
238  inline const _Tp&
239  min(const _Tp& __a, const _Tp& __b, _Compare __comp)
240  {
241  //return __comp(__b, __a) ? __b : __a;
242  if (__comp(__b, __a))
243  return __b;
244  return __a;
245  }
246 
247  /**
248  * @brief This does what you think it does.
249  * @ingroup sorting_algorithms
250  * @param __a A thing of arbitrary type.
251  * @param __b Another thing of arbitrary type.
252  * @param __comp A @link comparison_functors comparison functor@endlink.
253  * @return The greater of the parameters.
254  *
255  * This will work on temporary expressions, since they are only evaluated
256  * once, unlike a preprocessor macro.
257  */
258  template<typename _Tp, typename _Compare>
259  inline const _Tp&
260  max(const _Tp& __a, const _Tp& __b, _Compare __comp)
261  {
262  //return __comp(__a, __b) ? __b : __a;
263  if (__comp(__a, __b))
264  return __b;
265  return __a;
266  }
267 
268  // If _Iterator is a __normal_iterator return its base (a plain pointer,
269  // normally) otherwise return it untouched. See copy, fill, ...
270  template<typename _Iterator>
271  struct _Niter_base
272  : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
273  { };
274 
275  template<typename _Iterator>
276  inline typename _Niter_base<_Iterator>::iterator_type
277  __niter_base(_Iterator __it)
278  { return std::_Niter_base<_Iterator>::_S_base(__it); }
279 
280  // Likewise, for move_iterator.
281  template<typename _Iterator>
282  struct _Miter_base
283  : _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
284  { };
285 
286  template<typename _Iterator>
287  inline typename _Miter_base<_Iterator>::iterator_type
288  __miter_base(_Iterator __it)
289  { return std::_Miter_base<_Iterator>::_S_base(__it); }
290 
291  // All of these auxiliary structs serve two purposes. (1) Replace
292  // calls to copy with memmove whenever possible. (Memmove, not memcpy,
293  // because the input and output ranges are permitted to overlap.)
294  // (2) If we're using random access iterators, then write the loop as
295  // a for loop with an explicit count.
296 
297  template<bool, bool, typename>
298  struct __copy_move
299  {
300  template<typename _II, typename _OI>
301  static _OI
302  __copy_m(_II __first, _II __last, _OI __result)
303  {
304  for (; __first != __last; ++__result, ++__first)
305  *__result = *__first;
306  return __result;
307  }
308  };
309 
310 #if __cplusplus >= 201103L
311  template<typename _Category>
312  struct __copy_move<true, false, _Category>
313  {
314  template<typename _II, typename _OI>
315  static _OI
316  __copy_m(_II __first, _II __last, _OI __result)
317  {
318  for (; __first != __last; ++__result, ++__first)
319  *__result = std::move(*__first);
320  return __result;
321  }
322  };
323 #endif
324 
325  template<>
326  struct __copy_move<false, false, random_access_iterator_tag>
327  {
328  template<typename _II, typename _OI>
329  static _OI
330  __copy_m(_II __first, _II __last, _OI __result)
331  {
332  typedef typename iterator_traits<_II>::difference_type _Distance;
333  for(_Distance __n = __last - __first; __n > 0; --__n)
334  {
335  *__result = *__first;
336  ++__first;
337  ++__result;
338  }
339  return __result;
340  }
341  };
342 
343 #if __cplusplus >= 201103L
344  template<>
345  struct __copy_move<true, false, random_access_iterator_tag>
346  {
347  template<typename _II, typename _OI>
348  static _OI
349  __copy_m(_II __first, _II __last, _OI __result)
350  {
351  typedef typename iterator_traits<_II>::difference_type _Distance;
352  for(_Distance __n = __last - __first; __n > 0; --__n)
353  {
354  *__result = std::move(*__first);
355  ++__first;
356  ++__result;
357  }
358  return __result;
359  }
360  };
361 #endif
362 
363  template<bool _IsMove>
364  struct __copy_move<_IsMove, true, random_access_iterator_tag>
365  {
366  template<typename _Tp>
367  static _Tp*
368  __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
369  {
370  const ptrdiff_t _Num = __last - __first;
371  if (_Num)
372  __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
373  return __result + _Num;
374  }
375  };
376 
377  template<bool _IsMove, typename _II, typename _OI>
378  inline _OI
379  __copy_move_a(_II __first, _II __last, _OI __result)
380  {
381  typedef typename iterator_traits<_II>::value_type _ValueTypeI;
382  typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
383  typedef typename iterator_traits<_II>::iterator_category _Category;
384  const bool __simple = (__is_trivial(_ValueTypeI)
385  && __is_pointer<_II>::__value
386  && __is_pointer<_OI>::__value
387  && __are_same<_ValueTypeI, _ValueTypeO>::__value);
388 
389  return std::__copy_move<_IsMove, __simple,
390  _Category>::__copy_m(__first, __last, __result);
391  }
392 
393  // Helpers for streambuf iterators (either istream or ostream).
394  // NB: avoid including <iosfwd>, relatively large.
395  template<typename _CharT>
396  struct char_traits;
397 
398  template<typename _CharT, typename _Traits>
399  class istreambuf_iterator;
400 
401  template<typename _CharT, typename _Traits>
402  class ostreambuf_iterator;
403 
404  template<bool _IsMove, typename _CharT>
405  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
406  ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
407  __copy_move_a2(_CharT*, _CharT*,
408  ostreambuf_iterator<_CharT, char_traits<_CharT> >);
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(const _CharT*, const _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  _CharT*>::__type
419  __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
420  istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
421 
422  template<bool _IsMove, typename _II, typename _OI>
423  inline _OI
424  __copy_move_a2(_II __first, _II __last, _OI __result)
425  {
426  return _OI(std::__copy_move_a<_IsMove>(std::__niter_base(__first),
427  std::__niter_base(__last),
428  std::__niter_base(__result)));
429  }
430 
431  /**
432  * @brief Copies the range [first,last) into result.
433  * @ingroup mutating_algorithms
434  * @param __first An input iterator.
435  * @param __last An input iterator.
436  * @param __result An output iterator.
437  * @return result + (first - last)
438  *
439  * This inline function will boil down to a call to @c memmove whenever
440  * possible. Failing that, if random access iterators are passed, then the
441  * loop count will be known (and therefore a candidate for compiler
442  * optimizations such as unrolling). Result may not be contained within
443  * [first,last); the copy_backward function should be used instead.
444  *
445  * Note that the end of the output range is permitted to be contained
446  * within [first,last).
447  */
448  template<typename _II, typename _OI>
449  inline _OI
450  copy(_II __first, _II __last, _OI __result)
451  {
452  // concept requirements
453  __glibcxx_function_requires(_InputIteratorConcept<_II>)
454  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
455  typename iterator_traits<_II>::value_type>)
456  __glibcxx_requires_valid_range(__first, __last);
457 
458  return (std::__copy_move_a2<__is_move_iterator<_II>::__value>
459  (std::__miter_base(__first), std::__miter_base(__last),
460  __result));
461  }
462 
463 #if __cplusplus >= 201103L
464  /**
465  * @brief Moves the range [first,last) into result.
466  * @ingroup mutating_algorithms
467  * @param __first An input iterator.
468  * @param __last An input iterator.
469  * @param __result An output iterator.
470  * @return result + (first - last)
471  *
472  * This inline function will boil down to a call to @c memmove whenever
473  * possible. Failing that, if random access iterators are passed, then the
474  * loop count will be known (and therefore a candidate for compiler
475  * optimizations such as unrolling). Result may not be contained within
476  * [first,last); the move_backward function should be used instead.
477  *
478  * Note that the end of the output range is permitted to be contained
479  * within [first,last).
480  */
481  template<typename _II, typename _OI>
482  inline _OI
483  move(_II __first, _II __last, _OI __result)
484  {
485  // concept requirements
486  __glibcxx_function_requires(_InputIteratorConcept<_II>)
487  __glibcxx_function_requires(_OutputIteratorConcept<_OI,
488  typename iterator_traits<_II>::value_type>)
489  __glibcxx_requires_valid_range(__first, __last);
490 
491  return std::__copy_move_a2<true>(std::__miter_base(__first),
492  std::__miter_base(__last), __result);
493  }
494 
495 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
496 #else
497 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
498 #endif
499 
500  template<bool, bool, typename>
501  struct __copy_move_backward
502  {
503  template<typename _BI1, typename _BI2>
504  static _BI2
505  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
506  {
507  while (__first != __last)
508  *--__result = *--__last;
509  return __result;
510  }
511  };
512 
513 #if __cplusplus >= 201103L
514  template<typename _Category>
515  struct __copy_move_backward<true, false, _Category>
516  {
517  template<typename _BI1, typename _BI2>
518  static _BI2
519  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
520  {
521  while (__first != __last)
522  *--__result = std::move(*--__last);
523  return __result;
524  }
525  };
526 #endif
527 
528  template<>
529  struct __copy_move_backward<false, false, random_access_iterator_tag>
530  {
531  template<typename _BI1, typename _BI2>
532  static _BI2
533  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
534  {
535  typename iterator_traits<_BI1>::difference_type __n;
536  for (__n = __last - __first; __n > 0; --__n)
537  *--__result = *--__last;
538  return __result;
539  }
540  };
541 
542 #if __cplusplus >= 201103L
543  template<>
544  struct __copy_move_backward<true, false, random_access_iterator_tag>
545  {
546  template<typename _BI1, typename _BI2>
547  static _BI2
548  __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
549  {
550  typename iterator_traits<_BI1>::difference_type __n;
551  for (__n = __last - __first; __n > 0; --__n)
552  *--__result = std::move(*--__last);
553  return __result;
554  }
555  };
556 #endif
557 
558  template<bool _IsMove>
559  struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
560  {
561  template<typename _Tp>
562  static _Tp*
563  __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
564  {
565  const ptrdiff_t _Num = __last - __first;
566  if (_Num)
567  __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
568  return __result - _Num;
569  }
570  };
571 
572  template<bool _IsMove, typename _BI1, typename _BI2>
573  inline _BI2
574  __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
575  {
576  typedef typename iterator_traits<_BI1>::value_type _ValueType1;
577  typedef typename iterator_traits<_BI2>::value_type _ValueType2;
578  typedef typename iterator_traits<_BI1>::iterator_category _Category;
579  const bool __simple = (__is_trivial(_ValueType1)
580  && __is_pointer<_BI1>::__value
581  && __is_pointer<_BI2>::__value
582  && __are_same<_ValueType1, _ValueType2>::__value);
583 
584  return std::__copy_move_backward<_IsMove, __simple,
585  _Category>::__copy_move_b(__first,
586  __last,
587  __result);
588  }
589 
590  template<bool _IsMove, typename _BI1, typename _BI2>
591  inline _BI2
592  __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
593  {
594  return _BI2(std::__copy_move_backward_a<_IsMove>
595  (std::__niter_base(__first), std::__niter_base(__last),
596  std::__niter_base(__result)));
597  }
598 
599  /**
600  * @brief Copies the range [first,last) into result.
601  * @ingroup mutating_algorithms
602  * @param __first A bidirectional iterator.
603  * @param __last A bidirectional iterator.
604  * @param __result A bidirectional iterator.
605  * @return result - (first - last)
606  *
607  * The function has the same effect as copy, but starts at the end of the
608  * range and works its way to the start, returning the start of the result.
609  * This inline function will boil down to a call to @c memmove whenever
610  * possible. Failing that, if random access iterators are passed, then the
611  * loop count will be known (and therefore a candidate for compiler
612  * optimizations such as unrolling).
613  *
614  * Result may not be in the range [first,last). Use copy instead. Note
615  * that the start of the output range may overlap [first,last).
616  */
617  template<typename _BI1, typename _BI2>
618  inline _BI2
619  copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
620  {
621  // concept requirements
622  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
623  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
624  __glibcxx_function_requires(_ConvertibleConcept<
625  typename iterator_traits<_BI1>::value_type,
626  typename iterator_traits<_BI2>::value_type>)
627  __glibcxx_requires_valid_range(__first, __last);
628 
629  return (std::__copy_move_backward_a2<__is_move_iterator<_BI1>::__value>
630  (std::__miter_base(__first), std::__miter_base(__last),
631  __result));
632  }
633 
634 #if __cplusplus >= 201103L
635  /**
636  * @brief Moves the range [first,last) into result.
637  * @ingroup mutating_algorithms
638  * @param __first A bidirectional iterator.
639  * @param __last A bidirectional iterator.
640  * @param __result A bidirectional iterator.
641  * @return result - (first - last)
642  *
643  * The function has the same effect as move, but starts at the end of the
644  * range and works its way to the start, returning the start of the result.
645  * This inline function will boil down to a call to @c memmove whenever
646  * possible. Failing that, if random access iterators are passed, then the
647  * loop count will be known (and therefore a candidate for compiler
648  * optimizations such as unrolling).
649  *
650  * Result may not be in the range (first,last]. Use move instead. Note
651  * that the start of the output range may overlap [first,last).
652  */
653  template<typename _BI1, typename _BI2>
654  inline _BI2
655  move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
656  {
657  // concept requirements
658  __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
659  __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
660  __glibcxx_function_requires(_ConvertibleConcept<
661  typename iterator_traits<_BI1>::value_type,
662  typename iterator_traits<_BI2>::value_type>)
663  __glibcxx_requires_valid_range(__first, __last);
664 
665  return std::__copy_move_backward_a2<true>(std::__miter_base(__first),
666  std::__miter_base(__last),
667  __result);
668  }
669 
670 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
671 #else
672 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
673 #endif
674 
675  template<typename _ForwardIterator, typename _Tp>
676  inline typename
677  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
678  __fill_a(_ForwardIterator __first, _ForwardIterator __last,
679  const _Tp& __value)
680  {
681  for (; __first != __last; ++__first)
682  *__first = __value;
683  }
684 
685  template<typename _ForwardIterator, typename _Tp>
686  inline typename
687  __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
688  __fill_a(_ForwardIterator __first, _ForwardIterator __last,
689  const _Tp& __value)
690  {
691  const _Tp __tmp = __value;
692  for (; __first != __last; ++__first)
693  *__first = __tmp;
694  }
695 
696  // Specialization: for char types we can use memset.
697  template<typename _Tp>
698  inline typename
699  __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
700  __fill_a(_Tp* __first, _Tp* __last, const _Tp& __c)
701  {
702  const _Tp __tmp = __c;
703  __builtin_memset(__first, static_cast<unsigned char>(__tmp),
704  __last - __first);
705  }
706 
707  /**
708  * @brief Fills the range [first,last) with copies of value.
709  * @ingroup mutating_algorithms
710  * @param __first A forward iterator.
711  * @param __last A forward iterator.
712  * @param __value A reference-to-const of arbitrary type.
713  * @return Nothing.
714  *
715  * This function fills a range with copies of the same value. For char
716  * types filling contiguous areas of memory, this becomes an inline call
717  * to @c memset or @c wmemset.
718  */
719  template<typename _ForwardIterator, typename _Tp>
720  inline void
721  fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
722  {
723  // concept requirements
724  __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
725  _ForwardIterator>)
726  __glibcxx_requires_valid_range(__first, __last);
727 
728  std::__fill_a(std::__niter_base(__first), std::__niter_base(__last),
729  __value);
730  }
731 
732  template<typename _OutputIterator, typename _Size, typename _Tp>
733  inline typename
734  __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
735  __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
736  {
737  for (__decltype(__n + 0) __niter = __n;
738  __niter > 0; --__niter, ++__first)
739  *__first = __value;
740  return __first;
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  const _Tp __tmp = __value;
749  for (__decltype(__n + 0) __niter = __n;
750  __niter > 0; --__niter, ++__first)
751  *__first = __tmp;
752  return __first;
753  }
754 
755  template<typename _Size, typename _Tp>
756  inline typename
757  __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, _Tp*>::__type
758  __fill_n_a(_Tp* __first, _Size __n, const _Tp& __c)
759  {
760  std::__fill_a(__first, __first + __n, __c);
761  return __first + __n;
762  }
763 
764  /**
765  * @brief Fills the range [first,first+n) with copies of value.
766  * @ingroup mutating_algorithms
767  * @param __first An output iterator.
768  * @param __n The count of copies to perform.
769  * @param __value A reference-to-const of arbitrary type.
770  * @return The iterator at first+n.
771  *
772  * This function fills a range with copies of the same value. For char
773  * types filling contiguous areas of memory, this becomes an inline call
774  * to @c memset or @ wmemset.
775  *
776  * _GLIBCXX_RESOLVE_LIB_DEFECTS
777  * DR 865. More algorithms that throw away information
778  */
779  template<typename _OI, typename _Size, typename _Tp>
780  inline _OI
781  fill_n(_OI __first, _Size __n, const _Tp& __value)
782  {
783  // concept requirements
784  __glibcxx_function_requires(_OutputIteratorConcept<_OI, _Tp>)
785 
786  return _OI(std::__fill_n_a(std::__niter_base(__first), __n, __value));
787  }
788 
789  template<bool _BoolType>
790  struct __equal
791  {
792  template<typename _II1, typename _II2>
793  static bool
794  equal(_II1 __first1, _II1 __last1, _II2 __first2)
795  {
796  for (; __first1 != __last1; ++__first1, ++__first2)
797  if (!(*__first1 == *__first2))
798  return false;
799  return true;
800  }
801  };
802 
803  template<>
804  struct __equal<true>
805  {
806  template<typename _Tp>
807  static bool
808  equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
809  {
810  return !__builtin_memcmp(__first1, __first2, sizeof(_Tp)
811  * (__last1 - __first1));
812  }
813  };
814 
815  template<typename _II1, typename _II2>
816  inline bool
817  __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
818  {
819  typedef typename iterator_traits<_II1>::value_type _ValueType1;
820  typedef typename iterator_traits<_II2>::value_type _ValueType2;
821  const bool __simple = ((__is_integer<_ValueType1>::__value
822  || __is_pointer<_ValueType1>::__value)
823  && __is_pointer<_II1>::__value
824  && __is_pointer<_II2>::__value
825  && __are_same<_ValueType1, _ValueType2>::__value);
826 
827  return std::__equal<__simple>::equal(__first1, __last1, __first2);
828  }
829 
830  template<typename, typename>
831  struct __lc_rai
832  {
833  template<typename _II1, typename _II2>
834  static _II1
835  __newlast1(_II1, _II1 __last1, _II2, _II2)
836  { return __last1; }
837 
838  template<typename _II>
839  static bool
840  __cnd2(_II __first, _II __last)
841  { return __first != __last; }
842  };
843 
844  template<>
845  struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
846  {
847  template<typename _RAI1, typename _RAI2>
848  static _RAI1
849  __newlast1(_RAI1 __first1, _RAI1 __last1,
850  _RAI2 __first2, _RAI2 __last2)
851  {
852  const typename iterator_traits<_RAI1>::difference_type
853  __diff1 = __last1 - __first1;
854  const typename iterator_traits<_RAI2>::difference_type
855  __diff2 = __last2 - __first2;
856  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
857  }
858 
859  template<typename _RAI>
860  static bool
861  __cnd2(_RAI, _RAI)
862  { return true; }
863  };
864 
865  template<bool _BoolType>
866  struct __lexicographical_compare
867  {
868  template<typename _II1, typename _II2>
869  static bool __lc(_II1, _II1, _II2, _II2);
870  };
871 
872  template<bool _BoolType>
873  template<typename _II1, typename _II2>
874  bool
875  __lexicographical_compare<_BoolType>::
876  __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
877  {
878  typedef typename iterator_traits<_II1>::iterator_category _Category1;
879  typedef typename iterator_traits<_II2>::iterator_category _Category2;
880  typedef std::__lc_rai<_Category1, _Category2> __rai_type;
881 
882  __last1 = __rai_type::__newlast1(__first1, __last1,
883  __first2, __last2);
884  for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
885  ++__first1, ++__first2)
886  {
887  if (*__first1 < *__first2)
888  return true;
889  if (*__first2 < *__first1)
890  return false;
891  }
892  return __first1 == __last1 && __first2 != __last2;
893  }
894 
895  template<>
896  struct __lexicographical_compare<true>
897  {
898  template<typename _Tp, typename _Up>
899  static bool
900  __lc(const _Tp* __first1, const _Tp* __last1,
901  const _Up* __first2, const _Up* __last2)
902  {
903  const size_t __len1 = __last1 - __first1;
904  const size_t __len2 = __last2 - __first2;
905  const int __result = __builtin_memcmp(__first1, __first2,
906  std::min(__len1, __len2));
907  return __result != 0 ? __result < 0 : __len1 < __len2;
908  }
909  };
910 
911  template<typename _II1, typename _II2>
912  inline bool
913  __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
914  _II2 __first2, _II2 __last2)
915  {
916  typedef typename iterator_traits<_II1>::value_type _ValueType1;
917  typedef typename iterator_traits<_II2>::value_type _ValueType2;
918  const bool __simple =
919  (__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
920  && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
921  && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
922  && __is_pointer<_II1>::__value
923  && __is_pointer<_II2>::__value);
924 
925  return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
926  __first2, __last2);
927  }
928 
929  /**
930  * @brief Finds the first position in which @a val could be inserted
931  * without changing the ordering.
932  * @param __first An iterator.
933  * @param __last Another iterator.
934  * @param __val The search term.
935  * @return An iterator pointing to the first element <em>not less
936  * than</em> @a val, or end() if every element is less than
937  * @a val.
938  * @ingroup binary_search_algorithms
939  */
940  template<typename _ForwardIterator, typename _Tp>
941  _ForwardIterator
942  lower_bound(_ForwardIterator __first, _ForwardIterator __last,
943  const _Tp& __val)
944  {
945 #ifdef _GLIBCXX_CONCEPT_CHECKS
946  typedef typename iterator_traits<_ForwardIterator>::value_type
947  _ValueType;
948 #endif
949  typedef typename iterator_traits<_ForwardIterator>::difference_type
950  _DistanceType;
951 
952  // concept requirements
953  __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
954  __glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
955  __glibcxx_requires_partitioned_lower(__first, __last, __val);
956 
957  _DistanceType __len = std::distance(__first, __last);
958 
959  while (__len > 0)
960  {
961  _DistanceType __half = __len >> 1;
962  _ForwardIterator __middle = __first;
963  std::advance(__middle, __half);
964  if (*__middle < __val)
965  {
966  __first = __middle;
967  ++__first;
968  __len = __len - __half - 1;
969  }
970  else
971  __len = __half;
972  }
973  return __first;
974  }
975 
976  /// This is a helper function for the sort routines and for random.tcc.
977  // Precondition: __n > 0.
978  inline _GLIBCXX_CONSTEXPR int
979  __lg(int __n)
980  { return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
981 
982  inline _GLIBCXX_CONSTEXPR unsigned
983  __lg(unsigned __n)
984  { return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
985 
986  inline _GLIBCXX_CONSTEXPR long
987  __lg(long __n)
988  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
989 
990  inline _GLIBCXX_CONSTEXPR unsigned long
991  __lg(unsigned long __n)
992  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
993 
994  inline _GLIBCXX_CONSTEXPR long long
995  __lg(long long __n)
996  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
997 
998  inline _GLIBCXX_CONSTEXPR unsigned long long
999  __lg(unsigned long long __n)
1000  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1001 
1002 _GLIBCXX_END_NAMESPACE_VERSION
1003 
1004 _GLIBCXX_BEGIN_NAMESPACE_ALGO
1005 
1006  /**
1007  * @brief Tests a range for element-wise equality.
1008  * @ingroup non_mutating_algorithms
1009  * @param __first1 An input iterator.
1010  * @param __last1 An input iterator.
1011  * @param __first2 An input iterator.
1012  * @return A boolean true or false.
1013  *
1014  * This compares the elements of two ranges using @c == and returns true or
1015  * false depending on whether all of the corresponding elements of the
1016  * ranges are equal.
1017  */
1018  template<typename _II1, typename _II2>
1019  inline bool
1020  equal(_II1 __first1, _II1 __last1, _II2 __first2)
1021  {
1022  // concept requirements
1023  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1024  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1025  __glibcxx_function_requires(_EqualOpConcept<
1026  typename iterator_traits<_II1>::value_type,
1027  typename iterator_traits<_II2>::value_type>)
1028  __glibcxx_requires_valid_range(__first1, __last1);
1029 
1030  return std::__equal_aux(std::__niter_base(__first1),
1031  std::__niter_base(__last1),
1032  std::__niter_base(__first2));
1033  }
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  * @param __binary_pred A binary predicate @link functors
1042  * functor@endlink.
1043  * @return A boolean true or false.
1044  *
1045  * This compares the elements of two ranges using the binary_pred
1046  * parameter, and returns true or
1047  * false depending on whether all of the corresponding elements of the
1048  * ranges are equal.
1049  */
1050  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1051  inline bool
1052  equal(_IIter1 __first1, _IIter1 __last1,
1053  _IIter2 __first2, _BinaryPredicate __binary_pred)
1054  {
1055  // concept requirements
1056  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1057  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1058  __glibcxx_requires_valid_range(__first1, __last1);
1059 
1060  for (; __first1 != __last1; ++__first1, ++__first2)
1061  if (!bool(__binary_pred(*__first1, *__first2)))
1062  return false;
1063  return true;
1064  }
1065 
1066 #if __cplusplus > 201103L
1067  /**
1068  * @brief Tests a range for element-wise equality.
1069  * @ingroup non_mutating_algorithms
1070  * @param __first1 An input iterator.
1071  * @param __last1 An input iterator.
1072  * @param __first2 An input iterator.
1073  * @param __last2 An input iterator.
1074  * @return A boolean true or false.
1075  *
1076  * This compares the elements of two ranges using @c == and returns true or
1077  * false depending on whether all of the corresponding elements of the
1078  * ranges are equal.
1079  */
1080  template<typename _II1, typename _II2>
1081  inline bool
1082  equal(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
1083  {
1084  // concept requirements
1085  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1086  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1087  __glibcxx_function_requires(_EqualOpConcept<
1088  typename iterator_traits<_II1>::value_type,
1089  typename iterator_traits<_II2>::value_type>)
1090  __glibcxx_requires_valid_range(__first1, __last1);
1091  __glibcxx_requires_valid_range(__first2, __last2);
1092 
1093  using _RATag = random_access_iterator_tag;
1094  using _Cat1 = typename iterator_traits<_II1>::iterator_category;
1095  using _Cat2 = typename iterator_traits<_II2>::iterator_category;
1096  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1097  if (_RAIters())
1098  {
1099  auto __d1 = std::distance(__first1, __last1);
1100  auto __d2 = std::distance(__first2, __last2);
1101  if (__d1 != __d2)
1102  return false;
1103  return std::equal(__first1, __last1, __first2);
1104  }
1105 
1106  for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1107  if (!(*__first1 == *__first2))
1108  return false;
1109  return __first1 == __last1 && __first2 == __last2;
1110  }
1111 
1112  /**
1113  * @brief Tests a range for element-wise equality.
1114  * @ingroup non_mutating_algorithms
1115  * @param __first1 An input iterator.
1116  * @param __last1 An input iterator.
1117  * @param __first2 An input iterator.
1118  * @param __last2 An input iterator.
1119  * @param __binary_pred A binary predicate @link functors
1120  * functor@endlink.
1121  * @return A boolean true or false.
1122  *
1123  * This compares the elements of two ranges using the binary_pred
1124  * parameter, and returns true or
1125  * false depending on whether all of the corresponding elements of the
1126  * ranges are equal.
1127  */
1128  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1129  inline bool
1130  equal(_IIter1 __first1, _IIter1 __last1,
1131  _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
1132  {
1133  // concept requirements
1134  __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1135  __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1136  __glibcxx_requires_valid_range(__first1, __last1);
1137  __glibcxx_requires_valid_range(__first2, __last2);
1138 
1139  using _RATag = random_access_iterator_tag;
1140  using _Cat1 = typename iterator_traits<_IIter1>::iterator_category;
1141  using _Cat2 = typename iterator_traits<_IIter2>::iterator_category;
1142  using _RAIters = __and_<is_same<_Cat1, _RATag>, is_same<_Cat2, _RATag>>;
1143  if (_RAIters())
1144  {
1145  auto __d1 = std::distance(__first1, __last1);
1146  auto __d2 = std::distance(__first2, __last2);
1147  if (__d1 != __d2)
1148  return false;
1149  return std::equal(__first1, __last1, __first2, __binary_pred);
1150  }
1151 
1152  for (; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
1153  if (!bool(__binary_pred(*__first1, *__first2)))
1154  return false;
1155  return __first1 == __last1 && __first2 == __last2;
1156  }
1157 #endif
1158 
1159  /**
1160  * @brief Performs @b dictionary comparison on ranges.
1161  * @ingroup sorting_algorithms
1162  * @param __first1 An input iterator.
1163  * @param __last1 An input iterator.
1164  * @param __first2 An input iterator.
1165  * @param __last2 An input iterator.
1166  * @return A boolean true or false.
1167  *
1168  * <em>Returns true if the sequence of elements defined by the range
1169  * [first1,last1) is lexicographically less than the sequence of elements
1170  * defined by the range [first2,last2). Returns false otherwise.</em>
1171  * (Quoted from [25.3.8]/1.) If the iterators are all character pointers,
1172  * then this is an inline call to @c memcmp.
1173  */
1174  template<typename _II1, typename _II2>
1175  inline bool
1176  lexicographical_compare(_II1 __first1, _II1 __last1,
1177  _II2 __first2, _II2 __last2)
1178  {
1179 #ifdef _GLIBCXX_CONCEPT_CHECKS
1180  // concept requirements
1181  typedef typename iterator_traits<_II1>::value_type _ValueType1;
1182  typedef typename iterator_traits<_II2>::value_type _ValueType2;
1183 #endif
1184  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1185  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1186  __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1187  __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1188  __glibcxx_requires_valid_range(__first1, __last1);
1189  __glibcxx_requires_valid_range(__first2, __last2);
1190 
1191  return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1192  std::__niter_base(__last1),
1193  std::__niter_base(__first2),
1194  std::__niter_base(__last2));
1195  }
1196 
1197  /**
1198  * @brief Performs @b dictionary comparison on ranges.
1199  * @ingroup sorting_algorithms
1200  * @param __first1 An input iterator.
1201  * @param __last1 An input iterator.
1202  * @param __first2 An input iterator.
1203  * @param __last2 An input iterator.
1204  * @param __comp A @link comparison_functors comparison functor@endlink.
1205  * @return A boolean true or false.
1206  *
1207  * The same as the four-parameter @c lexicographical_compare, but uses the
1208  * comp parameter instead of @c <.
1209  */
1210  template<typename _II1, typename _II2, typename _Compare>
1211  bool
1212  lexicographical_compare(_II1 __first1, _II1 __last1,
1213  _II2 __first2, _II2 __last2, _Compare __comp)
1214  {
1215  typedef typename iterator_traits<_II1>::iterator_category _Category1;
1216  typedef typename iterator_traits<_II2>::iterator_category _Category2;
1217  typedef std::__lc_rai<_Category1, _Category2> __rai_type;
1218 
1219  // concept requirements
1220  __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1221  __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1222  __glibcxx_requires_valid_range(__first1, __last1);
1223  __glibcxx_requires_valid_range(__first2, __last2);
1224 
1225  __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1226  for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1227  ++__first1, ++__first2)
1228  {
1229  if (__comp(*__first1, *__first2))
1230  return true;
1231  if (__comp(*__first2, *__first1))
1232  return false;
1233  }
1234  return __first1 == __last1 && __first2 != __last2;
1235  }
1236 
1237  /**
1238  * @brief Finds the places in ranges which don't match.
1239  * @ingroup non_mutating_algorithms
1240  * @param __first1 An input iterator.
1241  * @param __last1 An input iterator.
1242  * @param __first2 An input iterator.
1243  * @return A pair of iterators pointing to the first mismatch.
1244  *
1245  * This compares the elements of two ranges using @c == and returns a pair
1246  * of iterators. The first iterator points into the first range, the
1247  * second iterator points into the second range, and the elements pointed
1248  * to by the iterators are not equal.
1249  */
1250  template<typename _InputIterator1, typename _InputIterator2>
1251  pair<_InputIterator1, _InputIterator2>
1252  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1253  _InputIterator2 __first2)
1254  {
1255  // concept requirements
1256  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1257  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1258  __glibcxx_function_requires(_EqualOpConcept<
1259  typename iterator_traits<_InputIterator1>::value_type,
1260  typename iterator_traits<_InputIterator2>::value_type>)
1261  __glibcxx_requires_valid_range(__first1, __last1);
1262 
1263  while (__first1 != __last1 && *__first1 == *__first2)
1264  {
1265  ++__first1;
1266  ++__first2;
1267  }
1268  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1269  }
1270 
1271  /**
1272  * @brief Finds the places in ranges which don't match.
1273  * @ingroup non_mutating_algorithms
1274  * @param __first1 An input iterator.
1275  * @param __last1 An input iterator.
1276  * @param __first2 An input iterator.
1277  * @param __binary_pred A binary predicate @link functors
1278  * functor@endlink.
1279  * @return A pair of iterators pointing to the first mismatch.
1280  *
1281  * This compares the elements of two ranges using the binary_pred
1282  * parameter, and returns a pair
1283  * of iterators. The first iterator points into the first range, the
1284  * second iterator points into the second range, and the elements pointed
1285  * to by the iterators are not equal.
1286  */
1287  template<typename _InputIterator1, typename _InputIterator2,
1288  typename _BinaryPredicate>
1289  pair<_InputIterator1, _InputIterator2>
1290  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1291  _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1292  {
1293  // concept requirements
1294  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1295  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1296  __glibcxx_requires_valid_range(__first1, __last1);
1297 
1298  while (__first1 != __last1 && bool(__binary_pred(*__first1, *__first2)))
1299  {
1300  ++__first1;
1301  ++__first2;
1302  }
1303  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1304  }
1305 
1306 #if __cplusplus > 201103L
1307  /**
1308  * @brief Finds the places in ranges which don't match.
1309  * @ingroup non_mutating_algorithms
1310  * @param __first1 An input iterator.
1311  * @param __last1 An input iterator.
1312  * @param __first2 An input iterator.
1313  * @param __last2 An input iterator.
1314  * @return A pair of iterators pointing to the first mismatch.
1315  *
1316  * This compares the elements of two ranges using @c == and returns a pair
1317  * of iterators. The first iterator points into the first range, the
1318  * second iterator points into the second range, and the elements pointed
1319  * to by the iterators are not equal.
1320  */
1321  template<typename _InputIterator1, typename _InputIterator2>
1322  pair<_InputIterator1, _InputIterator2>
1323  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1324  _InputIterator2 __first2, _InputIterator2 __last2)
1325  {
1326  // concept requirements
1327  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1328  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1329  __glibcxx_function_requires(_EqualOpConcept<
1330  typename iterator_traits<_InputIterator1>::value_type,
1331  typename iterator_traits<_InputIterator2>::value_type>)
1332  __glibcxx_requires_valid_range(__first1, __last1);
1333  __glibcxx_requires_valid_range(__first2, __last2);
1334 
1335  while (__first1 != __last1 && __first2 != __last2
1336  && *__first1 == *__first2)
1337  {
1338  ++__first1;
1339  ++__first2;
1340  }
1341  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1342  }
1343 
1344  /**
1345  * @brief Finds the places in ranges which don't match.
1346  * @ingroup non_mutating_algorithms
1347  * @param __first1 An input iterator.
1348  * @param __last1 An input iterator.
1349  * @param __first2 An input iterator.
1350  * @param __last2 An input iterator.
1351  * @param __binary_pred A binary predicate @link functors
1352  * functor@endlink.
1353  * @return A pair of iterators pointing to the first mismatch.
1354  *
1355  * This compares the elements of two ranges using the binary_pred
1356  * parameter, 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  typename _BinaryPredicate>
1363  pair<_InputIterator1, _InputIterator2>
1364  mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1365  _InputIterator2 __first2, _InputIterator2 __last2,
1366  _BinaryPredicate __binary_pred)
1367  {
1368  // concept requirements
1369  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1370  __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1371  __glibcxx_requires_valid_range(__first1, __last1);
1372  __glibcxx_requires_valid_range(__first2, __last2);
1373 
1374  while (__first1 != __last1 && __first2 != __last2
1375  && bool(__binary_pred(*__first1, *__first2)))
1376  {
1377  ++__first1;
1378  ++__first2;
1379  }
1380  return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1381  }
1382 #endif
1383 
1384 _GLIBCXX_END_NAMESPACE_ALGO
1385 } // namespace std
1386 
1387 // NB: This file is included within many other C++ includes, as a way
1388 // of getting the base algorithms. So, make sure that parallel bits
1389 // come in too if requested.
1390 #ifdef _GLIBCXX_PARALLEL
1391 # include <parallel/algobase.h>
1392 #endif
1393 
1394 #endif