libstdc++
stl_algobase.h
Go to the documentation of this file.
00001 // Core algorithmic facilities -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2013 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  *
00027  * Copyright (c) 1994
00028  * Hewlett-Packard Company
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Hewlett-Packard Company makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  *
00038  *
00039  * Copyright (c) 1996-1998
00040  * Silicon Graphics Computer Systems, Inc.
00041  *
00042  * Permission to use, copy, modify, distribute and sell this software
00043  * and its documentation for any purpose is hereby granted without fee,
00044  * provided that the above copyright notice appear in all copies and
00045  * that both that copyright notice and this permission notice appear
00046  * in supporting documentation.  Silicon Graphics makes no
00047  * representations about the suitability of this software for any
00048  * purpose.  It is provided "as is" without express or implied warranty.
00049  */
00050 
00051 /** @file bits/stl_algobase.h
00052  *  This is an internal header file, included by other library headers.
00053  *  Do not attempt to use it directly. @headername{algorithm}
00054  */
00055 
00056 #ifndef _STL_ALGOBASE_H
00057 #define _STL_ALGOBASE_H 1
00058 
00059 #include <bits/c++config.h>
00060 #include <bits/functexcept.h>
00061 #include <bits/cpp_type_traits.h>
00062 #include <ext/type_traits.h>
00063 #include <ext/numeric_traits.h>
00064 #include <bits/stl_pair.h>
00065 #include <bits/stl_iterator_base_types.h>
00066 #include <bits/stl_iterator_base_funcs.h>
00067 #include <bits/stl_iterator.h>
00068 #include <bits/concept_check.h>
00069 #include <debug/debug.h>
00070 #include <bits/move.h> // For std::swap and _GLIBCXX_MOVE
00071 
00072 namespace std _GLIBCXX_VISIBILITY(default)
00073 {
00074 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00075 
00076 #if __cplusplus < 201103L
00077   // See http://gcc.gnu.org/ml/libstdc++/2004-08/msg00167.html: in a
00078   // nutshell, we are partially implementing the resolution of DR 187,
00079   // when it's safe, i.e., the value_types are equal.
00080   template<bool _BoolType>
00081     struct __iter_swap
00082     {
00083       template<typename _ForwardIterator1, typename _ForwardIterator2>
00084         static void
00085         iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
00086         {
00087           typedef typename iterator_traits<_ForwardIterator1>::value_type
00088             _ValueType1;
00089           _ValueType1 __tmp = _GLIBCXX_MOVE(*__a);
00090           *__a = _GLIBCXX_MOVE(*__b);
00091           *__b = _GLIBCXX_MOVE(__tmp);
00092     }
00093     };
00094 
00095   template<>
00096     struct __iter_swap<true>
00097     {
00098       template<typename _ForwardIterator1, typename _ForwardIterator2>
00099         static void 
00100         iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
00101         {
00102           swap(*__a, *__b);
00103         }
00104     };
00105 #endif
00106 
00107   /**
00108    *  @brief Swaps the contents of two iterators.
00109    *  @ingroup mutating_algorithms
00110    *  @param  __a  An iterator.
00111    *  @param  __b  Another iterator.
00112    *  @return   Nothing.
00113    *
00114    *  This function swaps the values pointed to by two iterators, not the
00115    *  iterators themselves.
00116   */
00117   template<typename _ForwardIterator1, typename _ForwardIterator2>
00118     inline void
00119     iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
00120     {
00121       // concept requirements
00122       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
00123                   _ForwardIterator1>)
00124       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
00125                   _ForwardIterator2>)
00126 
00127 #if __cplusplus < 201103L
00128       typedef typename iterator_traits<_ForwardIterator1>::value_type
00129     _ValueType1;
00130       typedef typename iterator_traits<_ForwardIterator2>::value_type
00131     _ValueType2;
00132 
00133       __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
00134                   _ValueType2>)
00135       __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
00136                   _ValueType1>)
00137 
00138       typedef typename iterator_traits<_ForwardIterator1>::reference
00139     _ReferenceType1;
00140       typedef typename iterator_traits<_ForwardIterator2>::reference
00141     _ReferenceType2;
00142       std::__iter_swap<__are_same<_ValueType1, _ValueType2>::__value
00143     && __are_same<_ValueType1&, _ReferenceType1>::__value
00144     && __are_same<_ValueType2&, _ReferenceType2>::__value>::
00145     iter_swap(__a, __b);
00146 #else
00147       swap(*__a, *__b);
00148 #endif
00149     }
00150 
00151   /**
00152    *  @brief Swap the elements of two sequences.
00153    *  @ingroup mutating_algorithms
00154    *  @param  __first1  A forward iterator.
00155    *  @param  __last1   A forward iterator.
00156    *  @param  __first2  A forward iterator.
00157    *  @return   An iterator equal to @p first2+(last1-first1).
00158    *
00159    *  Swaps each element in the range @p [first1,last1) with the
00160    *  corresponding element in the range @p [first2,(last1-first1)).
00161    *  The ranges must not overlap.
00162   */
00163   template<typename _ForwardIterator1, typename _ForwardIterator2>
00164     _ForwardIterator2
00165     swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
00166         _ForwardIterator2 __first2)
00167     {
00168       // concept requirements
00169       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
00170                   _ForwardIterator1>)
00171       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
00172                   _ForwardIterator2>)
00173       __glibcxx_requires_valid_range(__first1, __last1);
00174 
00175       for (; __first1 != __last1; ++__first1, ++__first2)
00176     std::iter_swap(__first1, __first2);
00177       return __first2;
00178     }
00179 
00180   /**
00181    *  @brief This does what you think it does.
00182    *  @ingroup sorting_algorithms
00183    *  @param  __a  A thing of arbitrary type.
00184    *  @param  __b  Another thing of arbitrary type.
00185    *  @return   The lesser of the parameters.
00186    *
00187    *  This is the simple classic generic implementation.  It will work on
00188    *  temporary expressions, since they are only evaluated once, unlike a
00189    *  preprocessor macro.
00190   */
00191   template<typename _Tp>
00192     inline const _Tp&
00193     min(const _Tp& __a, const _Tp& __b)
00194     {
00195       // concept requirements
00196       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
00197       //return __b < __a ? __b : __a;
00198       if (__b < __a)
00199     return __b;
00200       return __a;
00201     }
00202 
00203   /**
00204    *  @brief This does what you think it does.
00205    *  @ingroup sorting_algorithms
00206    *  @param  __a  A thing of arbitrary type.
00207    *  @param  __b  Another thing of arbitrary type.
00208    *  @return   The greater of the parameters.
00209    *
00210    *  This is the simple classic generic implementation.  It will work on
00211    *  temporary expressions, since they are only evaluated once, unlike a
00212    *  preprocessor macro.
00213   */
00214   template<typename _Tp>
00215     inline const _Tp&
00216     max(const _Tp& __a, const _Tp& __b)
00217     {
00218       // concept requirements
00219       __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
00220       //return  __a < __b ? __b : __a;
00221       if (__a < __b)
00222     return __b;
00223       return __a;
00224     }
00225 
00226   /**
00227    *  @brief This does what you think it does.
00228    *  @ingroup sorting_algorithms
00229    *  @param  __a  A thing of arbitrary type.
00230    *  @param  __b  Another thing of arbitrary type.
00231    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
00232    *  @return   The lesser of the parameters.
00233    *
00234    *  This will work on temporary expressions, since they are only evaluated
00235    *  once, unlike a preprocessor macro.
00236   */
00237   template<typename _Tp, typename _Compare>
00238     inline const _Tp&
00239     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
00240     {
00241       //return __comp(__b, __a) ? __b : __a;
00242       if (__comp(__b, __a))
00243     return __b;
00244       return __a;
00245     }
00246 
00247   /**
00248    *  @brief This does what you think it does.
00249    *  @ingroup sorting_algorithms
00250    *  @param  __a  A thing of arbitrary type.
00251    *  @param  __b  Another thing of arbitrary type.
00252    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
00253    *  @return   The greater of the parameters.
00254    *
00255    *  This will work on temporary expressions, since they are only evaluated
00256    *  once, unlike a preprocessor macro.
00257   */
00258   template<typename _Tp, typename _Compare>
00259     inline const _Tp&
00260     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
00261     {
00262       //return __comp(__a, __b) ? __b : __a;
00263       if (__comp(__a, __b))
00264     return __b;
00265       return __a;
00266     }
00267 
00268   // If _Iterator is a __normal_iterator return its base (a plain pointer,
00269   // normally) otherwise return it untouched.  See copy, fill, ... 
00270   template<typename _Iterator>
00271     struct _Niter_base
00272     : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
00273     { };
00274 
00275   template<typename _Iterator>
00276     inline typename _Niter_base<_Iterator>::iterator_type
00277     __niter_base(_Iterator __it)
00278     { return std::_Niter_base<_Iterator>::_S_base(__it); }
00279 
00280   // Likewise, for move_iterator.
00281   template<typename _Iterator>
00282     struct _Miter_base
00283     : _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
00284     { };
00285 
00286   template<typename _Iterator>
00287     inline typename _Miter_base<_Iterator>::iterator_type
00288     __miter_base(_Iterator __it)
00289     { return std::_Miter_base<_Iterator>::_S_base(__it); }
00290 
00291   // All of these auxiliary structs serve two purposes.  (1) Replace
00292   // calls to copy with memmove whenever possible.  (Memmove, not memcpy,
00293   // because the input and output ranges are permitted to overlap.)
00294   // (2) If we're using random access iterators, then write the loop as
00295   // a for loop with an explicit count.
00296 
00297   template<bool, bool, typename>
00298     struct __copy_move
00299     {
00300       template<typename _II, typename _OI>
00301         static _OI
00302         __copy_m(_II __first, _II __last, _OI __result)
00303         {
00304       for (; __first != __last; ++__result, ++__first)
00305         *__result = *__first;
00306       return __result;
00307     }
00308     };
00309 
00310 #if __cplusplus >= 201103L
00311   template<typename _Category>
00312     struct __copy_move<true, false, _Category>
00313     {
00314       template<typename _II, typename _OI>
00315         static _OI
00316         __copy_m(_II __first, _II __last, _OI __result)
00317         {
00318       for (; __first != __last; ++__result, ++__first)
00319         *__result = std::move(*__first);
00320       return __result;
00321     }
00322     };
00323 #endif
00324 
00325   template<>
00326     struct __copy_move<false, false, random_access_iterator_tag>
00327     {
00328       template<typename _II, typename _OI>
00329         static _OI
00330         __copy_m(_II __first, _II __last, _OI __result)
00331         { 
00332       typedef typename iterator_traits<_II>::difference_type _Distance;
00333       for(_Distance __n = __last - __first; __n > 0; --__n)
00334         {
00335           *__result = *__first;
00336           ++__first;
00337           ++__result;
00338         }
00339       return __result;
00340     }
00341     };
00342 
00343 #if __cplusplus >= 201103L
00344   template<>
00345     struct __copy_move<true, false, random_access_iterator_tag>
00346     {
00347       template<typename _II, typename _OI>
00348         static _OI
00349         __copy_m(_II __first, _II __last, _OI __result)
00350         { 
00351       typedef typename iterator_traits<_II>::difference_type _Distance;
00352       for(_Distance __n = __last - __first; __n > 0; --__n)
00353         {
00354           *__result = std::move(*__first);
00355           ++__first;
00356           ++__result;
00357         }
00358       return __result;
00359     }
00360     };
00361 #endif
00362 
00363   template<bool _IsMove>
00364     struct __copy_move<_IsMove, true, random_access_iterator_tag>
00365     {
00366       template<typename _Tp>
00367         static _Tp*
00368         __copy_m(const _Tp* __first, const _Tp* __last, _Tp* __result)
00369         {
00370       const ptrdiff_t _Num = __last - __first;
00371       if (_Num)
00372         __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
00373       return __result + _Num;
00374     }
00375     };
00376 
00377   template<bool _IsMove, typename _II, typename _OI>
00378     inline _OI
00379     __copy_move_a(_II __first, _II __last, _OI __result)
00380     {
00381       typedef typename iterator_traits<_II>::value_type _ValueTypeI;
00382       typedef typename iterator_traits<_OI>::value_type _ValueTypeO;
00383       typedef typename iterator_traits<_II>::iterator_category _Category;
00384       const bool __simple = (__is_trivial(_ValueTypeI)
00385                          && __is_pointer<_II>::__value
00386                          && __is_pointer<_OI>::__value
00387                  && __are_same<_ValueTypeI, _ValueTypeO>::__value);
00388 
00389       return std::__copy_move<_IsMove, __simple,
00390                           _Category>::__copy_m(__first, __last, __result);
00391     }
00392 
00393   // Helpers for streambuf iterators (either istream or ostream).
00394   // NB: avoid including <iosfwd>, relatively large.
00395   template<typename _CharT>
00396     struct char_traits;
00397 
00398   template<typename _CharT, typename _Traits>
00399     class istreambuf_iterator;
00400 
00401   template<typename _CharT, typename _Traits>
00402     class ostreambuf_iterator;
00403 
00404   template<bool _IsMove, typename _CharT>
00405     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value, 
00406          ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
00407     __copy_move_a2(_CharT*, _CharT*,
00408            ostreambuf_iterator<_CharT, char_traits<_CharT> >);
00409 
00410   template<bool _IsMove, typename _CharT>
00411     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value, 
00412          ostreambuf_iterator<_CharT, char_traits<_CharT> > >::__type
00413     __copy_move_a2(const _CharT*, const _CharT*,
00414            ostreambuf_iterator<_CharT, char_traits<_CharT> >);
00415 
00416   template<bool _IsMove, typename _CharT>
00417     typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value,
00418                     _CharT*>::__type
00419     __copy_move_a2(istreambuf_iterator<_CharT, char_traits<_CharT> >,
00420            istreambuf_iterator<_CharT, char_traits<_CharT> >, _CharT*);
00421 
00422   template<bool _IsMove, typename _II, typename _OI>
00423     inline _OI
00424     __copy_move_a2(_II __first, _II __last, _OI __result)
00425     {
00426       return _OI(std::__copy_move_a<_IsMove>(std::__niter_base(__first),
00427                          std::__niter_base(__last),
00428                          std::__niter_base(__result)));
00429     }
00430 
00431   /**
00432    *  @brief Copies the range [first,last) into result.
00433    *  @ingroup mutating_algorithms
00434    *  @param  __first  An input iterator.
00435    *  @param  __last   An input iterator.
00436    *  @param  __result An output iterator.
00437    *  @return   result + (first - last)
00438    *
00439    *  This inline function will boil down to a call to @c memmove whenever
00440    *  possible.  Failing that, if random access iterators are passed, then the
00441    *  loop count will be known (and therefore a candidate for compiler
00442    *  optimizations such as unrolling).  Result may not be contained within
00443    *  [first,last); the copy_backward function should be used instead.
00444    *
00445    *  Note that the end of the output range is permitted to be contained
00446    *  within [first,last).
00447   */
00448   template<typename _II, typename _OI>
00449     inline _OI
00450     copy(_II __first, _II __last, _OI __result)
00451     {
00452       // concept requirements
00453       __glibcxx_function_requires(_InputIteratorConcept<_II>)
00454       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
00455         typename iterator_traits<_II>::value_type>)
00456       __glibcxx_requires_valid_range(__first, __last);
00457 
00458       return (std::__copy_move_a2<__is_move_iterator<_II>::__value>
00459           (std::__miter_base(__first), std::__miter_base(__last),
00460            __result));
00461     }
00462 
00463 #if __cplusplus >= 201103L
00464   /**
00465    *  @brief Moves the range [first,last) into result.
00466    *  @ingroup mutating_algorithms
00467    *  @param  __first  An input iterator.
00468    *  @param  __last   An input iterator.
00469    *  @param  __result An output iterator.
00470    *  @return   result + (first - last)
00471    *
00472    *  This inline function will boil down to a call to @c memmove whenever
00473    *  possible.  Failing that, if random access iterators are passed, then the
00474    *  loop count will be known (and therefore a candidate for compiler
00475    *  optimizations such as unrolling).  Result may not be contained within
00476    *  [first,last); the move_backward function should be used instead.
00477    *
00478    *  Note that the end of the output range is permitted to be contained
00479    *  within [first,last).
00480   */
00481   template<typename _II, typename _OI>
00482     inline _OI
00483     move(_II __first, _II __last, _OI __result)
00484     {
00485       // concept requirements
00486       __glibcxx_function_requires(_InputIteratorConcept<_II>)
00487       __glibcxx_function_requires(_OutputIteratorConcept<_OI,
00488         typename iterator_traits<_II>::value_type>)
00489       __glibcxx_requires_valid_range(__first, __last);
00490 
00491       return std::__copy_move_a2<true>(std::__miter_base(__first),
00492                        std::__miter_base(__last), __result);
00493     }
00494 
00495 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::move(_Tp, _Up, _Vp)
00496 #else
00497 #define _GLIBCXX_MOVE3(_Tp, _Up, _Vp) std::copy(_Tp, _Up, _Vp)
00498 #endif
00499 
00500   template<bool, bool, typename>
00501     struct __copy_move_backward
00502     {
00503       template<typename _BI1, typename _BI2>
00504         static _BI2
00505         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
00506         {
00507       while (__first != __last)
00508         *--__result = *--__last;
00509       return __result;
00510     }
00511     };
00512 
00513 #if __cplusplus >= 201103L
00514   template<typename _Category>
00515     struct __copy_move_backward<true, false, _Category>
00516     {
00517       template<typename _BI1, typename _BI2>
00518         static _BI2
00519         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
00520         {
00521       while (__first != __last)
00522         *--__result = std::move(*--__last);
00523       return __result;
00524     }
00525     };
00526 #endif
00527 
00528   template<>
00529     struct __copy_move_backward<false, false, random_access_iterator_tag>
00530     {
00531       template<typename _BI1, typename _BI2>
00532         static _BI2
00533         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
00534         {
00535       typename iterator_traits<_BI1>::difference_type __n;
00536       for (__n = __last - __first; __n > 0; --__n)
00537         *--__result = *--__last;
00538       return __result;
00539     }
00540     };
00541 
00542 #if __cplusplus >= 201103L
00543   template<>
00544     struct __copy_move_backward<true, false, random_access_iterator_tag>
00545     {
00546       template<typename _BI1, typename _BI2>
00547         static _BI2
00548         __copy_move_b(_BI1 __first, _BI1 __last, _BI2 __result)
00549         {
00550       typename iterator_traits<_BI1>::difference_type __n;
00551       for (__n = __last - __first; __n > 0; --__n)
00552         *--__result = std::move(*--__last);
00553       return __result;
00554     }
00555     };
00556 #endif
00557 
00558   template<bool _IsMove>
00559     struct __copy_move_backward<_IsMove, true, random_access_iterator_tag>
00560     {
00561       template<typename _Tp>
00562         static _Tp*
00563         __copy_move_b(const _Tp* __first, const _Tp* __last, _Tp* __result)
00564         {
00565       const ptrdiff_t _Num = __last - __first;
00566       if (_Num)
00567         __builtin_memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
00568       return __result - _Num;
00569     }
00570     };
00571 
00572   template<bool _IsMove, typename _BI1, typename _BI2>
00573     inline _BI2
00574     __copy_move_backward_a(_BI1 __first, _BI1 __last, _BI2 __result)
00575     {
00576       typedef typename iterator_traits<_BI1>::value_type _ValueType1;
00577       typedef typename iterator_traits<_BI2>::value_type _ValueType2;
00578       typedef typename iterator_traits<_BI1>::iterator_category _Category;
00579       const bool __simple = (__is_trivial(_ValueType1)
00580                          && __is_pointer<_BI1>::__value
00581                          && __is_pointer<_BI2>::__value
00582                  && __are_same<_ValueType1, _ValueType2>::__value);
00583 
00584       return std::__copy_move_backward<_IsMove, __simple,
00585                                    _Category>::__copy_move_b(__first,
00586                                  __last,
00587                                  __result);
00588     }
00589 
00590   template<bool _IsMove, typename _BI1, typename _BI2>
00591     inline _BI2
00592     __copy_move_backward_a2(_BI1 __first, _BI1 __last, _BI2 __result)
00593     {
00594       return _BI2(std::__copy_move_backward_a<_IsMove>
00595           (std::__niter_base(__first), std::__niter_base(__last),
00596            std::__niter_base(__result)));
00597     }
00598 
00599   /**
00600    *  @brief Copies the range [first,last) into result.
00601    *  @ingroup mutating_algorithms
00602    *  @param  __first  A bidirectional iterator.
00603    *  @param  __last   A bidirectional iterator.
00604    *  @param  __result A bidirectional iterator.
00605    *  @return   result - (first - last)
00606    *
00607    *  The function has the same effect as copy, but starts at the end of the
00608    *  range and works its way to the start, returning the start of the result.
00609    *  This inline function will boil down to a call to @c memmove whenever
00610    *  possible.  Failing that, if random access iterators are passed, then the
00611    *  loop count will be known (and therefore a candidate for compiler
00612    *  optimizations such as unrolling).
00613    *
00614    *  Result may not be in the range [first,last).  Use copy instead.  Note
00615    *  that the start of the output range may overlap [first,last).
00616   */
00617   template<typename _BI1, typename _BI2>
00618     inline _BI2
00619     copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
00620     {
00621       // concept requirements
00622       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
00623       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
00624       __glibcxx_function_requires(_ConvertibleConcept<
00625         typename iterator_traits<_BI1>::value_type,
00626         typename iterator_traits<_BI2>::value_type>)
00627       __glibcxx_requires_valid_range(__first, __last);
00628 
00629       return (std::__copy_move_backward_a2<__is_move_iterator<_BI1>::__value>
00630           (std::__miter_base(__first), std::__miter_base(__last),
00631            __result));
00632     }
00633 
00634 #if __cplusplus >= 201103L
00635   /**
00636    *  @brief Moves the range [first,last) into result.
00637    *  @ingroup mutating_algorithms
00638    *  @param  __first  A bidirectional iterator.
00639    *  @param  __last   A bidirectional iterator.
00640    *  @param  __result A bidirectional iterator.
00641    *  @return   result - (first - last)
00642    *
00643    *  The function has the same effect as move, but starts at the end of the
00644    *  range and works its way to the start, returning the start of the result.
00645    *  This inline function will boil down to a call to @c memmove whenever
00646    *  possible.  Failing that, if random access iterators are passed, then the
00647    *  loop count will be known (and therefore a candidate for compiler
00648    *  optimizations such as unrolling).
00649    *
00650    *  Result may not be in the range (first,last].  Use move instead.  Note
00651    *  that the start of the output range may overlap [first,last).
00652   */
00653   template<typename _BI1, typename _BI2>
00654     inline _BI2
00655     move_backward(_BI1 __first, _BI1 __last, _BI2 __result)
00656     {
00657       // concept requirements
00658       __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
00659       __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
00660       __glibcxx_function_requires(_ConvertibleConcept<
00661         typename iterator_traits<_BI1>::value_type,
00662         typename iterator_traits<_BI2>::value_type>)
00663       __glibcxx_requires_valid_range(__first, __last);
00664 
00665       return std::__copy_move_backward_a2<true>(std::__miter_base(__first),
00666                         std::__miter_base(__last),
00667                         __result);
00668     }
00669 
00670 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::move_backward(_Tp, _Up, _Vp)
00671 #else
00672 #define _GLIBCXX_MOVE_BACKWARD3(_Tp, _Up, _Vp) std::copy_backward(_Tp, _Up, _Vp)
00673 #endif
00674 
00675   template<typename _ForwardIterator, typename _Tp>
00676     inline typename
00677     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
00678     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
00679          const _Tp& __value)
00680     {
00681       for (; __first != __last; ++__first)
00682     *__first = __value;
00683     }
00684     
00685   template<typename _ForwardIterator, typename _Tp>
00686     inline typename
00687     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
00688     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
00689          const _Tp& __value)
00690     {
00691       const _Tp __tmp = __value;
00692       for (; __first != __last; ++__first)
00693     *__first = __tmp;
00694     }
00695 
00696   // Specialization: for char types we can use memset.
00697   template<typename _Tp>
00698     inline typename
00699     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, void>::__type
00700     __fill_a(_Tp* __first, _Tp* __last, const _Tp& __c)
00701     {
00702       const _Tp __tmp = __c;
00703       __builtin_memset(__first, static_cast<unsigned char>(__tmp),
00704                __last - __first);
00705     }
00706 
00707   /**
00708    *  @brief Fills the range [first,last) with copies of value.
00709    *  @ingroup mutating_algorithms
00710    *  @param  __first  A forward iterator.
00711    *  @param  __last   A forward iterator.
00712    *  @param  __value  A reference-to-const of arbitrary type.
00713    *  @return   Nothing.
00714    *
00715    *  This function fills a range with copies of the same value.  For char
00716    *  types filling contiguous areas of memory, this becomes an inline call
00717    *  to @c memset or @c wmemset.
00718   */
00719   template<typename _ForwardIterator, typename _Tp>
00720     inline void
00721     fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
00722     {
00723       // concept requirements
00724       __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
00725                   _ForwardIterator>)
00726       __glibcxx_requires_valid_range(__first, __last);
00727 
00728       std::__fill_a(std::__niter_base(__first), std::__niter_base(__last),
00729             __value);
00730     }
00731 
00732   template<typename _OutputIterator, typename _Size, typename _Tp>
00733     inline typename
00734     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
00735     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
00736     {
00737       for (__decltype(__n + 0) __niter = __n;
00738        __niter > 0; --__niter, ++__first)
00739     *__first = __value;
00740       return __first;
00741     }
00742 
00743   template<typename _OutputIterator, typename _Size, typename _Tp>
00744     inline typename
00745     __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
00746     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
00747     {
00748       const _Tp __tmp = __value;
00749       for (__decltype(__n + 0) __niter = __n;
00750        __niter > 0; --__niter, ++__first)
00751     *__first = __tmp;
00752       return __first;
00753     }
00754 
00755   template<typename _Size, typename _Tp>
00756     inline typename
00757     __gnu_cxx::__enable_if<__is_byte<_Tp>::__value, _Tp*>::__type
00758     __fill_n_a(_Tp* __first, _Size __n, const _Tp& __c)
00759     {
00760       std::__fill_a(__first, __first + __n, __c);
00761       return __first + __n;
00762     }
00763 
00764   /**
00765    *  @brief Fills the range [first,first+n) with copies of value.
00766    *  @ingroup mutating_algorithms
00767    *  @param  __first  An output iterator.
00768    *  @param  __n      The count of copies to perform.
00769    *  @param  __value  A reference-to-const of arbitrary type.
00770    *  @return   The iterator at first+n.
00771    *
00772    *  This function fills a range with copies of the same value.  For char
00773    *  types filling contiguous areas of memory, this becomes an inline call
00774    *  to @c memset or @ wmemset.
00775    *
00776    *  _GLIBCXX_RESOLVE_LIB_DEFECTS
00777    *  DR 865. More algorithms that throw away information
00778   */
00779   template<typename _OI, typename _Size, typename _Tp>
00780     inline _OI
00781     fill_n(_OI __first, _Size __n, const _Tp& __value)
00782     {
00783       // concept requirements
00784       __glibcxx_function_requires(_OutputIteratorConcept<_OI, _Tp>)
00785 
00786       return _OI(std::__fill_n_a(std::__niter_base(__first), __n, __value));
00787     }
00788 
00789   template<bool _BoolType>
00790     struct __equal
00791     {
00792       template<typename _II1, typename _II2>
00793         static bool
00794         equal(_II1 __first1, _II1 __last1, _II2 __first2)
00795         {
00796       for (; __first1 != __last1; ++__first1, ++__first2)
00797         if (!(*__first1 == *__first2))
00798           return false;
00799       return true;
00800     }
00801     };
00802 
00803   template<>
00804     struct __equal<true>
00805     {
00806       template<typename _Tp>
00807         static bool
00808         equal(const _Tp* __first1, const _Tp* __last1, const _Tp* __first2)
00809         {
00810       return !__builtin_memcmp(__first1, __first2, sizeof(_Tp)
00811                    * (__last1 - __first1));
00812     }
00813     };
00814 
00815   template<typename _II1, typename _II2>
00816     inline bool
00817     __equal_aux(_II1 __first1, _II1 __last1, _II2 __first2)
00818     {
00819       typedef typename iterator_traits<_II1>::value_type _ValueType1;
00820       typedef typename iterator_traits<_II2>::value_type _ValueType2;
00821       const bool __simple = ((__is_integer<_ValueType1>::__value
00822                   || __is_pointer<_ValueType1>::__value)
00823                          && __is_pointer<_II1>::__value
00824                          && __is_pointer<_II2>::__value
00825                  && __are_same<_ValueType1, _ValueType2>::__value);
00826 
00827       return std::__equal<__simple>::equal(__first1, __last1, __first2);
00828     }
00829 
00830 
00831   template<typename, typename>
00832     struct __lc_rai
00833     {
00834       template<typename _II1, typename _II2>
00835         static _II1
00836         __newlast1(_II1, _II1 __last1, _II2, _II2)
00837         { return __last1; }
00838 
00839       template<typename _II>
00840         static bool
00841         __cnd2(_II __first, _II __last)
00842         { return __first != __last; }
00843     };
00844 
00845   template<>
00846     struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
00847     {
00848       template<typename _RAI1, typename _RAI2>
00849         static _RAI1
00850         __newlast1(_RAI1 __first1, _RAI1 __last1,
00851            _RAI2 __first2, _RAI2 __last2)
00852         {
00853       const typename iterator_traits<_RAI1>::difference_type
00854         __diff1 = __last1 - __first1;
00855       const typename iterator_traits<_RAI2>::difference_type
00856         __diff2 = __last2 - __first2;
00857       return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
00858     }
00859 
00860       template<typename _RAI>
00861         static bool
00862         __cnd2(_RAI, _RAI)
00863         { return true; }
00864     };
00865 
00866   template<bool _BoolType>
00867     struct __lexicographical_compare
00868     {
00869       template<typename _II1, typename _II2>
00870         static bool __lc(_II1, _II1, _II2, _II2);
00871     };
00872 
00873   template<bool _BoolType>
00874     template<typename _II1, typename _II2>
00875       bool
00876       __lexicographical_compare<_BoolType>::
00877       __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
00878       {
00879     typedef typename iterator_traits<_II1>::iterator_category _Category1;
00880     typedef typename iterator_traits<_II2>::iterator_category _Category2;
00881     typedef std::__lc_rai<_Category1, _Category2>   __rai_type;
00882     
00883     __last1 = __rai_type::__newlast1(__first1, __last1,
00884                      __first2, __last2);
00885     for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
00886          ++__first1, ++__first2)
00887       {
00888         if (*__first1 < *__first2)
00889           return true;
00890         if (*__first2 < *__first1)
00891           return false;
00892       }
00893     return __first1 == __last1 && __first2 != __last2;
00894       }
00895 
00896   template<>
00897     struct __lexicographical_compare<true>
00898     {
00899       template<typename _Tp, typename _Up>
00900         static bool
00901         __lc(const _Tp* __first1, const _Tp* __last1,
00902          const _Up* __first2, const _Up* __last2)
00903     {
00904       const size_t __len1 = __last1 - __first1;
00905       const size_t __len2 = __last2 - __first2;
00906       const int __result = __builtin_memcmp(__first1, __first2,
00907                         std::min(__len1, __len2));
00908       return __result != 0 ? __result < 0 : __len1 < __len2;
00909     }
00910     };
00911 
00912   template<typename _II1, typename _II2>
00913     inline bool
00914     __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
00915                   _II2 __first2, _II2 __last2)
00916     {
00917       typedef typename iterator_traits<_II1>::value_type _ValueType1;
00918       typedef typename iterator_traits<_II2>::value_type _ValueType2;
00919       const bool __simple =
00920     (__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
00921      && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
00922      && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
00923      && __is_pointer<_II1>::__value
00924      && __is_pointer<_II2>::__value);
00925 
00926       return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
00927                                 __first2, __last2);
00928     }
00929 
00930   /**
00931    *  @brief Finds the first position in which @a val could be inserted
00932    *         without changing the ordering.
00933    *  @param  __first   An iterator.
00934    *  @param  __last    Another iterator.
00935    *  @param  __val     The search term.
00936    *  @return         An iterator pointing to the first element <em>not less
00937    *                  than</em> @a val, or end() if every element is less than 
00938    *                  @a val.
00939    *  @ingroup binary_search_algorithms
00940   */
00941   template<typename _ForwardIterator, typename _Tp>
00942     _ForwardIterator
00943     lower_bound(_ForwardIterator __first, _ForwardIterator __last,
00944         const _Tp& __val)
00945     {
00946 #ifdef _GLIBCXX_CONCEPT_CHECKS
00947       typedef typename iterator_traits<_ForwardIterator>::value_type
00948     _ValueType;
00949 #endif
00950       typedef typename iterator_traits<_ForwardIterator>::difference_type
00951     _DistanceType;
00952 
00953       // concept requirements
00954       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
00955       __glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
00956       __glibcxx_requires_partitioned_lower(__first, __last, __val);
00957 
00958       _DistanceType __len = std::distance(__first, __last);
00959 
00960       while (__len > 0)
00961     {
00962       _DistanceType __half = __len >> 1;
00963       _ForwardIterator __middle = __first;
00964       std::advance(__middle, __half);
00965       if (*__middle < __val)
00966         {
00967           __first = __middle;
00968           ++__first;
00969           __len = __len - __half - 1;
00970         }
00971       else
00972         __len = __half;
00973     }
00974       return __first;
00975     }
00976 
00977   /// This is a helper function for the sort routines and for random.tcc.
00978   //  Precondition: __n > 0.
00979   inline _GLIBCXX_CONSTEXPR int
00980   __lg(int __n)
00981   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
00982 
00983   inline _GLIBCXX_CONSTEXPR unsigned
00984   __lg(unsigned __n)
00985   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
00986 
00987   inline _GLIBCXX_CONSTEXPR long
00988   __lg(long __n)
00989   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
00990 
00991   inline _GLIBCXX_CONSTEXPR unsigned long
00992   __lg(unsigned long __n)
00993   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
00994 
00995   inline _GLIBCXX_CONSTEXPR long long
00996   __lg(long long __n)
00997   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
00998 
00999   inline _GLIBCXX_CONSTEXPR unsigned long long
01000   __lg(unsigned long long __n)
01001   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
01002 
01003 _GLIBCXX_END_NAMESPACE_VERSION
01004 
01005 _GLIBCXX_BEGIN_NAMESPACE_ALGO
01006 
01007   /**
01008    *  @brief Tests a range for element-wise equality.
01009    *  @ingroup non_mutating_algorithms
01010    *  @param  __first1  An input iterator.
01011    *  @param  __last1   An input iterator.
01012    *  @param  __first2  An input iterator.
01013    *  @return   A boolean true or false.
01014    *
01015    *  This compares the elements of two ranges using @c == and returns true or
01016    *  false depending on whether all of the corresponding elements of the
01017    *  ranges are equal.
01018   */
01019   template<typename _II1, typename _II2>
01020     inline bool
01021     equal(_II1 __first1, _II1 __last1, _II2 __first2)
01022     {
01023       // concept requirements
01024       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
01025       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
01026       __glibcxx_function_requires(_EqualOpConcept<
01027         typename iterator_traits<_II1>::value_type,
01028         typename iterator_traits<_II2>::value_type>)
01029       __glibcxx_requires_valid_range(__first1, __last1);
01030 
01031       return std::__equal_aux(std::__niter_base(__first1),
01032                   std::__niter_base(__last1),
01033                   std::__niter_base(__first2));
01034     }
01035 
01036   /**
01037    *  @brief Tests a range for element-wise equality.
01038    *  @ingroup non_mutating_algorithms
01039    *  @param  __first1  An input iterator.
01040    *  @param  __last1   An input iterator.
01041    *  @param  __first2  An input iterator.
01042    *  @param __binary_pred A binary predicate @link functors
01043    *                  functor@endlink.
01044    *  @return         A boolean true or false.
01045    *
01046    *  This compares the elements of two ranges using the binary_pred
01047    *  parameter, and returns true or
01048    *  false depending on whether all of the corresponding elements of the
01049    *  ranges are equal.
01050   */
01051   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
01052     inline bool
01053     equal(_IIter1 __first1, _IIter1 __last1,
01054       _IIter2 __first2, _BinaryPredicate __binary_pred)
01055     {
01056       // concept requirements
01057       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
01058       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
01059       __glibcxx_requires_valid_range(__first1, __last1);
01060 
01061       for (; __first1 != __last1; ++__first1, ++__first2)
01062     if (!bool(__binary_pred(*__first1, *__first2)))
01063       return false;
01064       return true;
01065     }
01066 
01067   /**
01068    *  @brief Performs @b dictionary comparison on ranges.
01069    *  @ingroup sorting_algorithms
01070    *  @param  __first1  An input iterator.
01071    *  @param  __last1   An input iterator.
01072    *  @param  __first2  An input iterator.
01073    *  @param  __last2   An input iterator.
01074    *  @return   A boolean true or false.
01075    *
01076    *  <em>Returns true if the sequence of elements defined by the range
01077    *  [first1,last1) is lexicographically less than the sequence of elements
01078    *  defined by the range [first2,last2).  Returns false otherwise.</em>
01079    *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
01080    *  then this is an inline call to @c memcmp.
01081   */
01082   template<typename _II1, typename _II2>
01083     inline bool
01084     lexicographical_compare(_II1 __first1, _II1 __last1,
01085                 _II2 __first2, _II2 __last2)
01086     {
01087 #ifdef _GLIBCXX_CONCEPT_CHECKS
01088       // concept requirements
01089       typedef typename iterator_traits<_II1>::value_type _ValueType1;
01090       typedef typename iterator_traits<_II2>::value_type _ValueType2;
01091 #endif
01092       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
01093       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
01094       __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
01095       __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
01096       __glibcxx_requires_valid_range(__first1, __last1);
01097       __glibcxx_requires_valid_range(__first2, __last2);
01098 
01099       return std::__lexicographical_compare_aux(std::__niter_base(__first1),
01100                         std::__niter_base(__last1),
01101                         std::__niter_base(__first2),
01102                         std::__niter_base(__last2));
01103     }
01104 
01105   /**
01106    *  @brief Performs @b dictionary comparison on ranges.
01107    *  @ingroup sorting_algorithms
01108    *  @param  __first1  An input iterator.
01109    *  @param  __last1   An input iterator.
01110    *  @param  __first2  An input iterator.
01111    *  @param  __last2   An input iterator.
01112    *  @param  __comp  A @link comparison_functors comparison functor@endlink.
01113    *  @return   A boolean true or false.
01114    *
01115    *  The same as the four-parameter @c lexicographical_compare, but uses the
01116    *  comp parameter instead of @c <.
01117   */
01118   template<typename _II1, typename _II2, typename _Compare>
01119     bool
01120     lexicographical_compare(_II1 __first1, _II1 __last1,
01121                 _II2 __first2, _II2 __last2, _Compare __comp)
01122     {
01123       typedef typename iterator_traits<_II1>::iterator_category _Category1;
01124       typedef typename iterator_traits<_II2>::iterator_category _Category2;
01125       typedef std::__lc_rai<_Category1, _Category2>     __rai_type;
01126 
01127       // concept requirements
01128       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
01129       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
01130       __glibcxx_requires_valid_range(__first1, __last1);
01131       __glibcxx_requires_valid_range(__first2, __last2);
01132 
01133       __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
01134       for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
01135        ++__first1, ++__first2)
01136     {
01137       if (__comp(*__first1, *__first2))
01138         return true;
01139       if (__comp(*__first2, *__first1))
01140         return false;
01141     }
01142       return __first1 == __last1 && __first2 != __last2;
01143     }
01144 
01145   /**
01146    *  @brief Finds the places in ranges which don't match.
01147    *  @ingroup non_mutating_algorithms
01148    *  @param  __first1  An input iterator.
01149    *  @param  __last1   An input iterator.
01150    *  @param  __first2  An input iterator.
01151    *  @return   A pair of iterators pointing to the first mismatch.
01152    *
01153    *  This compares the elements of two ranges using @c == and returns a pair
01154    *  of iterators.  The first iterator points into the first range, the
01155    *  second iterator points into the second range, and the elements pointed
01156    *  to by the iterators are not equal.
01157   */
01158   template<typename _InputIterator1, typename _InputIterator2>
01159     pair<_InputIterator1, _InputIterator2>
01160     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
01161          _InputIterator2 __first2)
01162     {
01163       // concept requirements
01164       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
01165       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
01166       __glibcxx_function_requires(_EqualOpConcept<
01167         typename iterator_traits<_InputIterator1>::value_type,
01168         typename iterator_traits<_InputIterator2>::value_type>)
01169       __glibcxx_requires_valid_range(__first1, __last1);
01170 
01171       while (__first1 != __last1 && *__first1 == *__first2)
01172         {
01173       ++__first1;
01174       ++__first2;
01175         }
01176       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
01177     }
01178 
01179   /**
01180    *  @brief Finds the places in ranges which don't match.
01181    *  @ingroup non_mutating_algorithms
01182    *  @param  __first1  An input iterator.
01183    *  @param  __last1   An input iterator.
01184    *  @param  __first2  An input iterator.
01185    *  @param __binary_pred A binary predicate @link functors
01186    *         functor@endlink.
01187    *  @return   A pair of iterators pointing to the first mismatch.
01188    *
01189    *  This compares the elements of two ranges using the binary_pred
01190    *  parameter, and returns a pair
01191    *  of iterators.  The first iterator points into the first range, the
01192    *  second iterator points into the second range, and the elements pointed
01193    *  to by the iterators are not equal.
01194   */
01195   template<typename _InputIterator1, typename _InputIterator2,
01196        typename _BinaryPredicate>
01197     pair<_InputIterator1, _InputIterator2>
01198     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
01199          _InputIterator2 __first2, _BinaryPredicate __binary_pred)
01200     {
01201       // concept requirements
01202       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
01203       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
01204       __glibcxx_requires_valid_range(__first1, __last1);
01205 
01206       while (__first1 != __last1 && bool(__binary_pred(*__first1, *__first2)))
01207         {
01208       ++__first1;
01209       ++__first2;
01210         }
01211       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
01212     }
01213 
01214 _GLIBCXX_END_NAMESPACE_ALGO
01215 } // namespace std
01216 
01217 // NB: This file is included within many other C++ includes, as a way
01218 // of getting the base algorithms. So, make sure that parallel bits
01219 // come in too if requested. 
01220 #ifdef _GLIBCXX_PARALLEL
01221 # include <parallel/algobase.h>
01222 #endif
01223 
01224 #endif