1// Core algorithmic facilities -*- C++ -*-
2
3// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
4// 2011 Free Software Foundation, Inc.
5//
6// This file is part of the GNU ISO C++ Library.  This library is free
7// software; you can redistribute it and/or modify it under the
8// terms of the GNU General Public License as published by the
9// Free Software Foundation; either version 3, or (at your option)
10// any later version.
11
12// This library is distributed in the hope that it will be useful,
13// but WITHOUT ANY WARRANTY; without even the implied warranty of
14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15// GNU General Public License for more details.
16
17// Under Section 7 of GPL version 3, you are granted additional
18// permissions described in the GCC Runtime Library Exception, version
19// 3.1, as published by the Free Software Foundation.
20
21// You should have received a copy of the GNU General Public License and
22// a copy of the GCC Runtime Library Exception along with this program;
23// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24// <http://www.gnu.org/licenses/>.
25
26/*
27 *
28 * Copyright (c) 1994
29 * Hewlett-Packard Company
30 *
31 * Permission to use, copy, modify, distribute and sell this software
32 * and its documentation for any purpose is hereby granted without fee,
33 * provided that the above copyright notice appear in all copies and
34 * that both that copyright notice and this permission notice appear
35 * in supporting documentation.  Hewlett-Packard Company makes no
36 * representations about the suitability of this software for any
37 * purpose.  It is provided "as is" without express or implied warranty.
38 *
39 *
40 * Copyright (c) 1996-1998
41 * Silicon Graphics Computer Systems, Inc.
42 *
43 * Permission to use, copy, modify, distribute and sell this software
44 * and its documentation for any purpose is hereby granted without fee,
45 * provided that the above copyright notice appear in all copies and
46 * that both that copyright notice and this permission notice appear
47 * in supporting documentation.  Silicon Graphics makes no
48 * representations about the suitability of this software for any
49 * purpose.  It is provided "as is" without express or implied warranty.
50 */
51
52/** @file bits/stl_algobase.h
53 *  This is an internal header file, included by other library headers.
54 *  Do not attempt to use it directly. @headername{algorithm}
55 */
56
57#ifndef _STL_ALGOBASE_H
58#define _STL_ALGOBASE_H 1
59
60#include <bits/c++config.h>
61#include <bits/functexcept.h>
62#include <bits/cpp_type_traits.h>
63#include <ext/type_traits.h>
64#include <ext/numeric_traits.h>
65#include <bits/stl_pair.h>
66#include <bits/stl_iterator_base_types.h>
67#include <bits/stl_iterator_base_funcs.h>
68#include <bits/stl_iterator.h>
69#include <bits/concept_check.h>
70#include <debug/debug.h>
71#include <bits/move.h> // For std::swap and _GLIBCXX_MOVE
72
73namespace std _GLIBCXX_VISIBILITY(default)
74{
75_GLIBCXX_BEGIN_NAMESPACE_VERSION
76
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
106  /**
107   *  @brief Swaps the contents of two iterators.
108   *  @ingroup mutating_algorithms
109   *  @param  __a  An iterator.
110   *  @param  __b  Another iterator.
111   *  @return   Nothing.
112   *
113   *  This function swaps the values pointed to by two iterators, not the
114   *  iterators themselves.
115  */
116  template<typename _ForwardIterator1, typename _ForwardIterator2>
117    inline void
118    iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
119    {
120      typedef typename iterator_traits<_ForwardIterator1>::value_type
121	_ValueType1;
122      typedef typename iterator_traits<_ForwardIterator2>::value_type
123	_ValueType2;
124
125      // concept requirements
126      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
127				  _ForwardIterator1>)
128      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
129				  _ForwardIterator2>)
130      __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
131				  _ValueType2>)
132      __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
133				  _ValueType1>)
134
135      typedef typename iterator_traits<_ForwardIterator1>::reference
136	_ReferenceType1;
137      typedef typename iterator_traits<_ForwardIterator2>::reference
138	_ReferenceType2;
139      std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
140	&& __are_same<_ValueType1&, _ReferenceType1>::__value
141	&& __are_same<_ValueType2&, _ReferenceType2>::__value>::
142	iter_swap(__a, __b);
143    }
144
145  /**
146   *  @brief Swap the elements of two sequences.
147   *  @ingroup mutating_algorithms
148   *  @param  __first1  A forward iterator.
149   *  @param  __last1   A forward iterator.
150   *  @param  __first2  A forward iterator.
151   *  @return   An iterator equal to @p first2+(last1-first1).
152   *
153   *  Swaps each element in the range @p [first1,last1) with the
154   *  corresponding element in the range @p [first2,(last1-first1)).
155   *  The ranges must not overlap.
156  */
157  template<typename _ForwardIterator1, typename _ForwardIterator2>
158    _ForwardIterator2
159    swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
160		_ForwardIterator2 __first2)
161    {
162      // concept requirements
163      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
164				  _ForwardIterator1>)
165      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
166				  _ForwardIterator2>)
167      __glibcxx_requires_valid_range(__first1, __last1);
168
169      for (; __first1 != __last1; ++__first1, ++__first2)
170	std::iter_swap(__first1, __first2);
171      return __first2;
172    }
173
174  /**
175   *  @brief This does what you think it does.
176   *  @ingroup sorting_algorithms
177   *  @param  __a  A thing of arbitrary type.
178   *  @param  __b  Another thing of arbitrary type.
179   *  @return   The lesser of the parameters.
180   *
181   *  This is the simple classic generic implementation.  It will work on
182   *  temporary expressions, since they are only evaluated once, unlike a
183   *  preprocessor macro.
184  */
185  template<typename _Tp>
186    inline const _Tp&
187    min(const _Tp& __a, const _Tp& __b)
188    {
189      // concept requirements
190      __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
191      //return __b < __a ? __b : __a;
192      if (__b < __a)
193	return __b;
194      return __a;
195    }
196
197  /**
198   *  @brief This does what you think it does.
199   *  @ingroup sorting_algorithms
200   *  @param  __a  A thing of arbitrary type.
201   *  @param  __b  Another thing of arbitrary type.
202   *  @return   The greater of the parameters.
203   *
204   *  This is the simple classic generic implementation.  It will work on
205   *  temporary expressions, since they are only evaluated once, unlike a
206   *  preprocessor macro.
207  */
208  template<typename _Tp>
209    inline const _Tp&
210    max(const _Tp& __a, const _Tp& __b)
211    {
212      // concept requirements
213      __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
214      //return  __a < __b ? __b : __a;
215      if (__a < __b)
216	return __b;
217      return __a;
218    }
219
220  /**
221   *  @brief This does what you think it does.
222   *  @ingroup sorting_algorithms
223   *  @param  __a  A thing of arbitrary type.
224   *  @param  __b  Another thing of arbitrary type.
225   *  @param  __comp  A @link comparison_functors comparison functor@endlink.
226   *  @return   The lesser of the parameters.
227   *
228   *  This will work on temporary expressions, since they are only evaluated
229   *  once, unlike a preprocessor macro.
230  */
231  template<typename _Tp, typename _Compare>
232    inline const _Tp&
233    min(const _Tp& __a, const _Tp& __b, _Compare __comp)
234    {
235      //return __comp(__b, __a) ? __b : __a;
236      if (__comp(__b, __a))
237	return __b;
238      return __a;
239    }
240
241  /**
242   *  @brief This does what you think it does.
243   *  @ingroup sorting_algorithms
244   *  @param  __a  A thing of arbitrary type.
245   *  @param  __b  Another thing of arbitrary type.
246   *  @param  __comp  A @link comparison_functors comparison functor@endlink.
247   *  @return   The greater of the parameters.
248   *
249   *  This will work on temporary expressions, since they are only evaluated
250   *  once, unlike a preprocessor macro.
251  */
252  template<typename _Tp, typename _Compare>
253    inline const _Tp&
254    max(const _Tp& __a, const _Tp& __b, _Compare __comp)
255    {
256      //return __comp(__a, __b) ? __b : __a;
257      if (__comp(__a, __b))
258	return __b;
259      return __a;
260    }
261
262  // If _Iterator is a __normal_iterator return its base (a plain pointer,
263  // normally) otherwise return it untouched.  See copy, fill, ...
264  template<typename _Iterator>
265    struct _Niter_base
266    : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
267    { };
268
269  template<typename _Iterator>
270    inline typename _Niter_base<_Iterator>::iterator_type
271    __niter_base(_Iterator __it)
272    { return std::_Niter_base<_Iterator>::_S_base(__it); }
273
274  // Likewise, for move_iterator.
275  template<typename _Iterator>
276    struct _Miter_base
277    : _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
278    { };
279
280  template<typename _Iterator>
281    inline typename _Miter_base<_Iterator>::iterator_type
282    __miter_base(_Iterator __it)
283    { return std::_Miter_base<_Iterator>::_S_base(__it); }
284
285  // All of these auxiliary structs serve two purposes.  (1) Replace
286  // calls to copy with memmove whenever possible.  (Memmove, not memcpy,
287  // because the input and output ranges are permitted to overlap.)
288  // (2) If we're using random access iterators, then write the loop as
289  // a for loop with an explicit count.
290
291  template<bool, bool, typename>
292    struct __copy_move
293    {
294      template<typename _II, typename _OI>
295        static _OI
296        __copy_m(_II __first, _II __last, _OI __result)
297        {
298	  for (; __first != __last; ++__result, ++__first)
299	    *__result = *__first;
300	  return __result;
301	}
302    };
303
304#ifdef __GXX_EXPERIMENTAL_CXX0X__
305  template<typename _Category>
306    struct __copy_move<true, false, _Category>
307    {
308      template<typename _II, typename _OI>
309        static _OI
310        __copy_m(_II __first, _II __last, _OI __result)
311        {
312	  for (; __first != __last; ++__result, ++__first)
313	    *__result = std::move(*__first);
314	  return __result;
315	}
316    };
317#endif
318
319  template<>
320    struct __copy_move<false, false, random_access_iterator_tag>
321    {
322      template<typename _II, typename _OI>
323        static _OI
324        __copy_m(_II __first, _II __last, _OI __result)
325        {
326	  typedef typename iterator_traits<_II>::difference_type _Distance;
327	  for(_Distance __n = __last - __first; __n > 0; --__n)
328	    {
329	      *__result = *__first;
330	      ++__first;
331	      ++__result;
332	    }
333	  return __result;
334	}
335    };
336
337#ifdef __GXX_EXPERIMENTAL_CXX0X__
338  template<>
339    struct __copy_move<true, false, random_access_iterator_tag>
340    {
341      template<typename _II, typename _OI>
342        static _OI
343        __copy_m(_II __first, _II __last, _OI __result)
344        {
345	  typedef typename iterator_traits<_II>::difference_type _Distance;
346	  for(_Distance __n = __last - __first; __n > 0; --__n)
347	    {
348	      *__result = std::move(*__first);
349	      ++__first;
350	      ++__result;
351	    }
352	  return __result;
353	}
354    };
355#endif
356
357  template<bool _IsMove>
358    struct __copy_move<_IsMove, true, random_access_iterator_tag>
359    {
360      template<typename _Tp>
361        static _Tp*
362        __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
363        {
364	  const ptrdiff_t _Num = __last - __first;
365	  if (_Num)
366	    __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
367	  return __result + _Num;
368	}
369    };
370
371  template<bool _IsMove, typename _II, typename _OI>
372    inline _OI
373    __copy_move_a(_II __first, _II __last, _OI __result)
374    {
375      typedef typename iterator_traits<_II>::value_type _ValueTypeI;
376      typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
377      typedef typename iterator_traits<_II>::iterator_category _Category;
378      const bool __simple = (__is_trivial(_ValueTypeI)
379	                     && __is_pointer<_II>::__value
380	                     && __is_pointer<_OI>::__value
381			     && __are_same<_ValueTypeI, _ValueTypeO>::__value);
382
383      return std::__copy_move<_IsMove, __simple,
384	                      _Category>::__copy_m(__first, __last, __result);
385    }
386
387  // Helpers for streambuf iterators (either istream or ostream).
388  // NB: avoid including <iosfwd>, relatively large.
389  template<typename _CharT>
390    struct char_traits;
391
392  template<typename _CharT, typename _Traits>
393    class istreambuf_iterator;
394
395  template<typename _CharT, typename _Traits>
396    class ostreambuf_iterator;
397
398  template<bool _IsMove, typename _CharT>
399    typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
400	     ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
401    __copy_move_a2(_CharT*, _CharT*,
402		   ostreambuf_iterator<_CharT, char_traits<_CharT> >);
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(const _CharT*, const _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				    _CharT*>::__type
413    __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
414		   istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
415
416  template<bool _IsMove, typename _II, typename _OI>
417    inline _OI
418    __copy_move_a2(_II __first, _II __last, _OI __result)
419    {
420      return _OI(std::__copy_move_a<_IsMove>(std::__niter_base(__first),
421					     std::__niter_base(__last),
422					     std::__niter_base(__result)));
423    }
424
425  /**
426   *  @brief Copies the range [first,last) into result.
427   *  @ingroup mutating_algorithms
428   *  @param  __first  An input iterator.
429   *  @param  __last   An input iterator.
430   *  @param  __result An output iterator.
431   *  @return   result + (first - last)
432   *
433   *  This inline function will boil down to a call to @c memmove whenever
434   *  possible.  Failing that, if random access iterators are passed, then the
435   *  loop count will be known (and therefore a candidate for compiler
436   *  optimizations such as unrolling).  Result may not be contained within
437   *  [first,last); the copy_backward function should be used instead.
438   *
439   *  Note that the end of the output range is permitted to be contained
440   *  within [first,last).
441  */
442  template<typename _II, typename _OI>
443    inline _OI
444    copy(_II __first, _II __last, _OI __result)
445    {
446      // concept requirements
447      __glibcxx_function_requires(_InputIteratorConcept<_II>)
448      __glibcxx_function_requires(_OutputIteratorConcept<_OI,
449	    typename iterator_traits<_II>::value_type>)
450      __glibcxx_requires_valid_range(__first, __last);
451
452      return (std::__copy_move_a2<__is_move_iterator<_II>::__value>
453	      (std::__miter_base(__first), std::__miter_base(__last),
454	       __result));
455    }
456
457#ifdef __GXX_EXPERIMENTAL_CXX0X__
458  /**
459   *  @brief Moves the range [first,last) into result.
460   *  @ingroup mutating_algorithms
461   *  @param  __first  An input iterator.
462   *  @param  __last   An input iterator.
463   *  @param  __result An output iterator.
464   *  @return   result + (first - last)
465   *
466   *  This inline function will boil down to a call to @c memmove whenever
467   *  possible.  Failing that, if random access iterators are passed, then the
468   *  loop count will be known (and therefore a candidate for compiler
469   *  optimizations such as unrolling).  Result may not be contained within
470   *  [first,last); the move_backward function should be used instead.
471   *
472   *  Note that the end of the output range is permitted to be contained
473   *  within [first,last).
474  */
475  template<typename _II, typename _OI>
476    inline _OI
477    move(_II __first, _II __last, _OI __result)
478    {
479      // concept requirements
480      __glibcxx_function_requires(_InputIteratorConcept<_II>)
481      __glibcxx_function_requires(_OutputIteratorConcept<_OI,
482	    typename iterator_traits<_II>::value_type>)
483      __glibcxx_requires_valid_range(__first, __last);
484
485      return std::__copy_move_a2<true>(std::__miter_base(__first),
486				       std::__miter_base(__last), __result);
487    }
488
489#define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
490#else
491#define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
492#endif
493
494  template<bool, bool, typename>
495    struct __copy_move_backward
496    {
497      template<typename _BI1, typename _BI2>
498        static _BI2
499        __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
500        {
501	  while (__first != __last)
502	    *--__result = *--__last;
503	  return __result;
504	}
505    };
506
507#ifdef __GXX_EXPERIMENTAL_CXX0X__
508  template<typename _Category>
509    struct __copy_move_backward<true, false, _Category>
510    {
511      template<typename _BI1, typename _BI2>
512        static _BI2
513        __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
514        {
515	  while (__first != __last)
516	    *--__result = std::move(*--__last);
517	  return __result;
518	}
519    };
520#endif
521
522  template<>
523    struct __copy_move_backward<false, false, random_access_iterator_tag>
524    {
525      template<typename _BI1, typename _BI2>
526        static _BI2
527        __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
528        {
529	  typename iterator_traits<_BI1>::difference_type __n;
530	  for (__n = __last - __first; __n > 0; --__n)
531	    *--__result = *--__last;
532	  return __result;
533	}
534    };
535
536#ifdef __GXX_EXPERIMENTAL_CXX0X__
537  template<>
538    struct __copy_move_backward<true, false, random_access_iterator_tag>
539    {
540      template<typename _BI1, typename _BI2>
541        static _BI2
542        __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
543        {
544	  typename iterator_traits<_BI1>::difference_type __n;
545	  for (__n = __last - __first; __n > 0; --__n)
546	    *--__result = std::move(*--__last);
547	  return __result;
548	}
549    };
550#endif
551
552  template<bool _IsMove>
553    struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
554    {
555      template<typename _Tp>
556        static _Tp*
557        __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
558        {
559	  const ptrdiff_t _Num = __last - __first;
560	  if (_Num)
561	    __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
562	  return __result - _Num;
563	}
564    };
565
566  template<bool _IsMove, typename _BI1, typename _BI2>
567    inline _BI2
568    __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
569    {
570      typedef typename iterator_traits<_BI1>::value_type _ValueType1;
571      typedef typename iterator_traits<_BI2>::value_type _ValueType2;
572      typedef typename iterator_traits<_BI1>::iterator_category _Category;
573      const bool __simple = (__is_trivial(_ValueType1)
574	                     && __is_pointer<_BI1>::__value
575	                     && __is_pointer<_BI2>::__value
576			     && __are_same<_ValueType1, _ValueType2>::__value);
577
578      return std::__copy_move_backward<_IsMove, __simple,
579	                               _Category>::__copy_move_b(__first,
580								 __last,
581								 __result);
582    }
583
584  template<bool _IsMove, typename _BI1, typename _BI2>
585    inline _BI2
586    __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
587    {
588      return _BI2(std::__copy_move_backward_a<_IsMove>
589		  (std::__niter_base(__first), std::__niter_base(__last),
590		   std::__niter_base(__result)));
591    }
592
593  /**
594   *  @brief Copies the range [first,last) into result.
595   *  @ingroup mutating_algorithms
596   *  @param  __first  A bidirectional iterator.
597   *  @param  __last   A bidirectional iterator.
598   *  @param  __result A bidirectional iterator.
599   *  @return   result - (first - last)
600   *
601   *  The function has the same effect as copy, but starts at the end of the
602   *  range and works its way to the start, returning the start of the result.
603   *  This inline function will boil down to a call to @c memmove whenever
604   *  possible.  Failing that, if random access iterators are passed, then the
605   *  loop count will be known (and therefore a candidate for compiler
606   *  optimizations such as unrolling).
607   *
608   *  Result may not be in the range [first,last).  Use copy instead.  Note
609   *  that the start of the output range may overlap [first,last).
610  */
611  template<typename _BI1, typename _BI2>
612    inline _BI2
613    copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
614    {
615      // concept requirements
616      __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
617      __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
618      __glibcxx_function_requires(_ConvertibleConcept<
619	    typename iterator_traits<_BI1>::value_type,
620	    typename iterator_traits<_BI2>::value_type>)
621      __glibcxx_requires_valid_range(__first, __last);
622
623      return (std::__copy_move_backward_a2<__is_move_iterator<_BI1>::__value>
624	      (std::__miter_base(__first), std::__miter_base(__last),
625	       __result));
626    }
627
628#ifdef __GXX_EXPERIMENTAL_CXX0X__
629  /**
630   *  @brief Moves the range [first,last) into result.
631   *  @ingroup mutating_algorithms
632   *  @param  __first  A bidirectional iterator.
633   *  @param  __last   A bidirectional iterator.
634   *  @param  __result A bidirectional iterator.
635   *  @return   result - (first - last)
636   *
637   *  The function has the same effect as move, but starts at the end of the
638   *  range and works its way to the start, returning the start of the result.
639   *  This inline function will boil down to a call to @c memmove whenever
640   *  possible.  Failing that, if random access iterators are passed, then the
641   *  loop count will be known (and therefore a candidate for compiler
642   *  optimizations such as unrolling).
643   *
644   *  Result may not be in the range (first,last].  Use move instead.  Note
645   *  that the start of the output range may overlap [first,last).
646  */
647  template<typename _BI1, typename _BI2>
648    inline _BI2
649    move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
650    {
651      // concept requirements
652      __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
653      __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
654      __glibcxx_function_requires(_ConvertibleConcept<
655	    typename iterator_traits<_BI1>::value_type,
656	    typename iterator_traits<_BI2>::value_type>)
657      __glibcxx_requires_valid_range(__first, __last);
658
659      return std::__copy_move_backward_a2<true>(std::__miter_base(__first),
660						std::__miter_base(__last),
661						__result);
662    }
663
664#define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
665#else
666#define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
667#endif
668
669  template<typename _ForwardIterator, typename _Tp>
670    inline typename
671    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
672    __fill_a(_ForwardIterator __first, _ForwardIterator __last,
673 	     const _Tp& __value)
674    {
675      for (; __first != __last; ++__first)
676	*__first = __value;
677    }
678
679  template<typename _ForwardIterator, typename _Tp>
680    inline typename
681    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
682    __fill_a(_ForwardIterator __first, _ForwardIterator __last,
683	     const _Tp& __value)
684    {
685      const _Tp __tmp = __value;
686      for (; __first != __last; ++__first)
687	*__first = __tmp;
688    }
689
690  // Specialization: for char types we can use memset.
691  template<typename _Tp>
692    inline typename
693    __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
694    __fill_a(_Tp* __first, _Tp* __last, const _Tp& __c)
695    {
696      const _Tp __tmp = __c;
697      __builtin_memset(__first, static_cast<unsigned char>(__tmp),
698		       __last - __first);
699    }
700
701  /**
702   *  @brief Fills the range [first,last) with copies of value.
703   *  @ingroup mutating_algorithms
704   *  @param  __first  A forward iterator.
705   *  @param  __last   A forward iterator.
706   *  @param  __value  A reference-to-const of arbitrary type.
707   *  @return   Nothing.
708   *
709   *  This function fills a range with copies of the same value.  For char
710   *  types filling contiguous areas of memory, this becomes an inline call
711   *  to @c memset or @c wmemset.
712  */
713  template<typename _ForwardIterator, typename _Tp>
714    inline void
715    fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
716    {
717      // concept requirements
718      __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
719				  _ForwardIterator>)
720      __glibcxx_requires_valid_range(__first, __last);
721
722      std::__fill_a(std::__niter_base(__first), std::__niter_base(__last),
723		    __value);
724    }
725
726  template<typename _OutputIterator, typename _Size, typename _Tp>
727    inline typename
728    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
729    __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
730    {
731      for (__decltype(__n + 0) __niter = __n;
732	   __niter > 0; --__niter, ++__first)
733	*__first = __value;
734      return __first;
735    }
736
737  template<typename _OutputIterator, typename _Size, typename _Tp>
738    inline typename
739    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
740    __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
741    {
742      const _Tp __tmp = __value;
743      for (__decltype(__n + 0) __niter = __n;
744	   __niter > 0; --__niter, ++__first)
745	*__first = __tmp;
746      return __first;
747    }
748
749  template<typename _Size, typename _Tp>
750    inline typename
751    __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, _Tp*>::__type
752    __fill_n_a(_Tp* __first, _Size __n, const _Tp& __c)
753    {
754      std::__fill_a(__first, __first + __n, __c);
755      return __first + __n;
756    }
757
758  /**
759   *  @brief Fills the range [first,first+n) with copies of value.
760   *  @ingroup mutating_algorithms
761   *  @param  __first  An output iterator.
762   *  @param  __n      The count of copies to perform.
763   *  @param  __value  A reference-to-const of arbitrary type.
764   *  @return   The iterator at first+n.
765   *
766   *  This function fills a range with copies of the same value.  For char
767   *  types filling contiguous areas of memory, this becomes an inline call
768   *  to @c memset or @ wmemset.
769   *
770   *  _GLIBCXX_RESOLVE_LIB_DEFECTS
771   *  DR 865. More algorithms that throw away information
772  */
773  template<typename _OI, typename _Size, typename _Tp>
774    inline _OI
775    fill_n(_OI __first, _Size __n, const _Tp& __value)
776    {
777      // concept requirements
778      __glibcxx_function_requires(_OutputIteratorConcept<_OI, _Tp>)
779
780      return _OI(std::__fill_n_a(std::__niter_base(__first), __n, __value));
781    }
782
783  template<bool _BoolType>
784    struct __equal
785    {
786      template<typename _II1, typename _II2>
787        static bool
788        equal(_II1 __first1, _II1 __last1, _II2 __first2)
789        {
790	  for (; __first1 != __last1; ++__first1, ++__first2)
791	    if (!(*__first1 == *__first2))
792	      return false;
793	  return true;
794	}
795    };
796
797  template<>
798    struct __equal<true>
799    {
800      template<typename _Tp>
801        static bool
802        equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
803        {
804	  return !__builtin_memcmp(__first1, __first2, sizeof(_Tp)
805				   * (__last1 - __first1));
806	}
807    };
808
809  template<typename _II1, typename _II2>
810    inline bool
811    __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
812    {
813      typedef typename iterator_traits<_II1>::value_type _ValueType1;
814      typedef typename iterator_traits<_II2>::value_type _ValueType2;
815      const bool __simple = ((__is_integer<_ValueType1>::__value
816			      || __is_pointer<_ValueType1>::__value)
817	                     && __is_pointer<_II1>::__value
818	                     && __is_pointer<_II2>::__value
819			     && __are_same<_ValueType1, _ValueType2>::__value);
820
821      return std::__equal<__simple>::equal(__first1, __last1, __first2);
822    }
823
824
825  template<typename, typename>
826    struct __lc_rai
827    {
828      template<typename _II1, typename _II2>
829        static _II1
830        __newlast1(_II1, _II1 __last1, _II2, _II2)
831        { return __last1; }
832
833      template<typename _II>
834        static bool
835        __cnd2(_II __first, _II __last)
836        { return __first != __last; }
837    };
838
839  template<>
840    struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
841    {
842      template<typename _RAI1, typename _RAI2>
843        static _RAI1
844        __newlast1(_RAI1 __first1, _RAI1 __last1,
845		   _RAI2 __first2, _RAI2 __last2)
846        {
847	  const typename iterator_traits<_RAI1>::difference_type
848	    __diff1 = __last1 - __first1;
849	  const typename iterator_traits<_RAI2>::difference_type
850	    __diff2 = __last2 - __first2;
851	  return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
852	}
853
854      template<typename _RAI>
855        static bool
856        __cnd2(_RAI, _RAI)
857        { return true; }
858    };
859
860  template<bool _BoolType>
861    struct __lexicographical_compare
862    {
863      template<typename _II1, typename _II2>
864        static bool __lc(_II1, _II1, _II2, _II2);
865    };
866
867  template<bool _BoolType>
868    template<typename _II1, typename _II2>
869      bool
870      __lexicographical_compare<_BoolType>::
871      __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
872      {
873	typedef typename iterator_traits<_II1>::iterator_category _Category1;
874	typedef typename iterator_traits<_II2>::iterator_category _Category2;
875	typedef std::__lc_rai<_Category1, _Category2> 	__rai_type;
876
877	__last1 = __rai_type::__newlast1(__first1, __last1,
878					 __first2, __last2);
879	for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
880	     ++__first1, ++__first2)
881	  {
882	    if (*__first1 < *__first2)
883	      return true;
884	    if (*__first2 < *__first1)
885	      return false;
886	  }
887	return __first1 == __last1 && __first2 != __last2;
888      }
889
890  template<>
891    struct __lexicographical_compare<true>
892    {
893      template<typename _Tp, typename _Up>
894        static bool
895        __lc(const _Tp* __first1, const _Tp* __last1,
896	     const _Up* __first2, const _Up* __last2)
897	{
898	  const size_t __len1 = __last1 - __first1;
899	  const size_t __len2 = __last2 - __first2;
900	  const int __result = __builtin_memcmp(__first1, __first2,
901						std::min(__len1, __len2));
902	  return __result != 0 ? __result < 0 : __len1 < __len2;
903	}
904    };
905
906  template<typename _II1, typename _II2>
907    inline bool
908    __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
909				  _II2 __first2, _II2 __last2)
910    {
911      typedef typename iterator_traits<_II1>::value_type _ValueType1;
912      typedef typename iterator_traits<_II2>::value_type _ValueType2;
913      const bool __simple =
914	(__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
915	 && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
916	 && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
917	 && __is_pointer<_II1>::__value
918	 && __is_pointer<_II2>::__value);
919
920      return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
921							    __first2, __last2);
922    }
923
924  /**
925   *  @brief Finds the first position in which @a val could be inserted
926   *         without changing the ordering.
927   *  @param  __first   An iterator.
928   *  @param  __last    Another iterator.
929   *  @param  __val     The search term.
930   *  @return         An iterator pointing to the first element <em>not less
931   *                  than</em> @a val, or end() if every element is less than
932   *                  @a val.
933   *  @ingroup binary_search_algorithms
934  */
935  template<typename _ForwardIterator, typename _Tp>
936    _ForwardIterator
937    lower_bound(_ForwardIterator __first, _ForwardIterator __last,
938		const _Tp& __val)
939    {
940      typedef typename iterator_traits<_ForwardIterator>::value_type
941	_ValueType;
942      typedef typename iterator_traits<_ForwardIterator>::difference_type
943	_DistanceType;
944
945      // concept requirements
946      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
947      __glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
948      __glibcxx_requires_partitioned_lower(__first, __last, __val);
949
950      _DistanceType __len = std::distance(__first, __last);
951
952      while (__len > 0)
953	{
954	  _DistanceType __half = __len >> 1;
955	  _ForwardIterator __middle = __first;
956	  std::advance(__middle, __half);
957	  if (*__middle < __val)
958	    {
959	      __first = __middle;
960	      ++__first;
961	      __len = __len - __half - 1;
962	    }
963	  else
964	    __len = __half;
965	}
966      return __first;
967    }
968
969  /// This is a helper function for the sort routines and for random.tcc.
970  //  Precondition: __n > 0.
971  template<typename _Size>
972    inline _Size
973    __lg(_Size __n)
974    {
975      _Size __k;
976      for (__k = 0; __n != 0; __n >>= 1)
977	++__k;
978      return __k - 1;
979    }
980
981  inline int
982  __lg(int __n)
983  { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
984
985  inline unsigned
986  __lg(unsigned __n)
987  { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
988
989  inline long
990  __lg(long __n)
991  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
992
993  inline unsigned long
994  __lg(unsigned long __n)
995  { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
996
997  inline long long
998  __lg(long long __n)
999  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1000
1001  inline unsigned long long
1002  __lg(unsigned long long __n)
1003  { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
1004
1005_GLIBCXX_END_NAMESPACE_VERSION
1006
1007_GLIBCXX_BEGIN_NAMESPACE_ALGO
1008
1009  /**
1010   *  @brief Tests a range for element-wise equality.
1011   *  @ingroup non_mutating_algorithms
1012   *  @param  __first1  An input iterator.
1013   *  @param  __last1   An input iterator.
1014   *  @param  __first2  An input iterator.
1015   *  @return   A boolean true or false.
1016   *
1017   *  This compares the elements of two ranges using @c == and returns true or
1018   *  false depending on whether all of the corresponding elements of the
1019   *  ranges are equal.
1020  */
1021  template<typename _II1, typename _II2>
1022    inline bool
1023    equal(_II1 __first1, _II1 __last1, _II2 __first2)
1024    {
1025      // concept requirements
1026      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1027      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1028      __glibcxx_function_requires(_EqualOpConcept<
1029	    typename iterator_traits<_II1>::value_type,
1030	    typename iterator_traits<_II2>::value_type>)
1031      __glibcxx_requires_valid_range(__first1, __last1);
1032
1033      return std::__equal_aux(std::__niter_base(__first1),
1034			      std::__niter_base(__last1),
1035			      std::__niter_base(__first2));
1036    }
1037
1038  /**
1039   *  @brief Tests a range for element-wise equality.
1040   *  @ingroup non_mutating_algorithms
1041   *  @param  __first1  An input iterator.
1042   *  @param  __last1   An input iterator.
1043   *  @param  __first2  An input iterator.
1044   *  @param __binary_pred A binary predicate @link functors
1045   *                  functor@endlink.
1046   *  @return         A boolean true or false.
1047   *
1048   *  This compares the elements of two ranges using the binary_pred
1049   *  parameter, and returns true or
1050   *  false depending on whether all of the corresponding elements of the
1051   *  ranges are equal.
1052  */
1053  template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1054    inline bool
1055    equal(_IIter1 __first1, _IIter1 __last1,
1056	  _IIter2 __first2, _BinaryPredicate __binary_pred)
1057    {
1058      // concept requirements
1059      __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1060      __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1061      __glibcxx_requires_valid_range(__first1, __last1);
1062
1063      for (; __first1 != __last1; ++__first1, ++__first2)
1064	if (!bool(__binary_pred(*__first1, *__first2)))
1065	  return false;
1066      return true;
1067    }
1068
1069  /**
1070   *  @brief Performs @b dictionary comparison on ranges.
1071   *  @ingroup sorting_algorithms
1072   *  @param  __first1  An input iterator.
1073   *  @param  __last1   An input iterator.
1074   *  @param  __first2  An input iterator.
1075   *  @param  __last2   An input iterator.
1076   *  @return   A boolean true or false.
1077   *
1078   *  <em>Returns true if the sequence of elements defined by the range
1079   *  [first1,last1) is lexicographically less than the sequence of elements
1080   *  defined by the range [first2,last2).  Returns false otherwise.</em>
1081   *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
1082   *  then this is an inline call to @c memcmp.
1083  */
1084  template<typename _II1, typename _II2>
1085    inline bool
1086    lexicographical_compare(_II1 __first1, _II1 __last1,
1087			    _II2 __first2, _II2 __last2)
1088    {
1089      // concept requirements
1090      typedef typename iterator_traits<_II1>::value_type _ValueType1;
1091      typedef typename iterator_traits<_II2>::value_type _ValueType2;
1092      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1093      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1094      __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1095      __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1096      __glibcxx_requires_valid_range(__first1, __last1);
1097      __glibcxx_requires_valid_range(__first2, __last2);
1098
1099      return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1100						std::__niter_base(__last1),
1101						std::__niter_base(__first2),
1102						std::__niter_base(__last2));
1103    }
1104
1105  /**
1106   *  @brief Performs @b dictionary comparison on ranges.
1107   *  @ingroup sorting_algorithms
1108   *  @param  __first1  An input iterator.
1109   *  @param  __last1   An input iterator.
1110   *  @param  __first2  An input iterator.
1111   *  @param  __last2   An input iterator.
1112   *  @param  __comp  A @link comparison_functors comparison functor@endlink.
1113   *  @return   A boolean true or false.
1114   *
1115   *  The same as the four-parameter @c lexicographical_compare, but uses the
1116   *  comp parameter instead of @c <.
1117  */
1118  template<typename _II1, typename _II2, typename _Compare>
1119    bool
1120    lexicographical_compare(_II1 __first1, _II1 __last1,
1121			    _II2 __first2, _II2 __last2, _Compare __comp)
1122    {
1123      typedef typename iterator_traits<_II1>::iterator_category _Category1;
1124      typedef typename iterator_traits<_II2>::iterator_category _Category2;
1125      typedef std::__lc_rai<_Category1, _Category2> 	__rai_type;
1126
1127      // concept requirements
1128      __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1129      __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1130      __glibcxx_requires_valid_range(__first1, __last1);
1131      __glibcxx_requires_valid_range(__first2, __last2);
1132
1133      __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1134      for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1135	   ++__first1, ++__first2)
1136	{
1137	  if (__comp(*__first1, *__first2))
1138	    return true;
1139	  if (__comp(*__first2, *__first1))
1140	    return false;
1141	}
1142      return __first1 == __last1 && __first2 != __last2;
1143    }
1144
1145  /**
1146   *  @brief Finds the places in ranges which don't match.
1147   *  @ingroup non_mutating_algorithms
1148   *  @param  __first1  An input iterator.
1149   *  @param  __last1   An input iterator.
1150   *  @param  __first2  An input iterator.
1151   *  @return   A pair of iterators pointing to the first mismatch.
1152   *
1153   *  This compares the elements of two ranges using @c == and returns a pair
1154   *  of iterators.  The first iterator points into the first range, the
1155   *  second iterator points into the second range, and the elements pointed
1156   *  to by the iterators are not equal.
1157  */
1158  template<typename _InputIterator1, typename _InputIterator2>
1159    pair<_InputIterator1, _InputIterator2>
1160    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1161	     _InputIterator2 __first2)
1162    {
1163      // concept requirements
1164      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1165      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1166      __glibcxx_function_requires(_EqualOpConcept<
1167	    typename iterator_traits<_InputIterator1>::value_type,
1168	    typename iterator_traits<_InputIterator2>::value_type>)
1169      __glibcxx_requires_valid_range(__first1, __last1);
1170
1171      while (__first1 != __last1 && *__first1 == *__first2)
1172        {
1173	  ++__first1;
1174	  ++__first2;
1175        }
1176      return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1177    }
1178
1179  /**
1180   *  @brief Finds the places in ranges which don't match.
1181   *  @ingroup non_mutating_algorithms
1182   *  @param  __first1  An input iterator.
1183   *  @param  __last1   An input iterator.
1184   *  @param  __first2  An input iterator.
1185   *  @param __binary_pred A binary predicate @link functors
1186   *         functor@endlink.
1187   *  @return   A pair of iterators pointing to the first mismatch.
1188   *
1189   *  This compares the elements of two ranges using the binary_pred
1190   *  parameter, and returns a pair
1191   *  of iterators.  The first iterator points into the first range, the
1192   *  second iterator points into the second range, and the elements pointed
1193   *  to by the iterators are not equal.
1194  */
1195  template<typename _InputIterator1, typename _InputIterator2,
1196	   typename _BinaryPredicate>
1197    pair<_InputIterator1, _InputIterator2>
1198    mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1199	     _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1200    {
1201      // concept requirements
1202      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1203      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1204      __glibcxx_requires_valid_range(__first1, __last1);
1205
1206      while (__first1 != __last1 && bool(__binary_pred(*__first1, *__first2)))
1207        {
1208	  ++__first1;
1209	  ++__first2;
1210        }
1211      return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1212    }
1213
1214_GLIBCXX_END_NAMESPACE_ALGO
1215} // namespace std
1216
1217// NB: This file is included within many other C++ includes, as a way
1218// of getting the base algorithms. So, make sure that parallel bits
1219// come in too if requested.
1220#ifdef _GLIBCXX_PARALLEL
1221# include <parallel/algobase.h>
1222#endif
1223
1224#endif
1225