libstdc++-v3/include/bits/stl_algobase.h

   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
  73 namespace 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<_II1>::__value
 817                              && __is_pointer<_II2>::__value
 818                              && __are_same<_ValueType1, _ValueType2>::__value);
 819
 820       return std::__equal<__simple>::equal(__first1, __last1, __first2);
 821     }
 822
 823
 824   template<typename, typename>
 825     struct __lc_rai
 826     {
 827       template<typename _II1, typename _II2>
 828         static _II1
 829         __newlast1(_II1, _II1 __last1, _II2, _II2)
 830         { return __last1; }
 831
 832       template<typename _II>
 833         static bool
 834         __cnd2(_II __first, _II __last)
 835         { return __first != __last; }
 836     };
 837
 838   template<>
 839     struct __lc_rai<random_access_iterator_tag, random_access_iterator_tag>
 840     {
 841       template<typename _RAI1, typename _RAI2>
 842         static _RAI1
 843         __newlast1(_RAI1 __first1, _RAI1 __last1,
 844                    _RAI2 __first2, _RAI2 __last2)
 845         {
 846           const typename iterator_traits<_RAI1>::difference_type
 847             __diff1 = __last1 - __first1;
 848           const typename iterator_traits<_RAI2>::difference_type
 849             __diff2 = __last2 - __first2;
 850           return __diff2 < __diff1 ? __first1 + __diff2 : __last1;
 851         }
 852
 853       template<typename _RAI>
 854         static bool
 855         __cnd2(_RAI, _RAI)
 856         { return true; }
 857     };
 858
 859   template<bool _BoolType>
 860     struct __lexicographical_compare
 861     {
 862       template<typename _II1, typename _II2>
 863         static bool __lc(_II1, _II1, _II2, _II2);
 864     };
 865
 866   template<bool _BoolType>
 867     template<typename _II1, typename _II2>
 868       bool
 869       __lexicographical_compare<_BoolType>::
 870       __lc(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2)
 871       {
 872         typedef typename iterator_traits<_II1>::iterator_category _Category1;
 873         typedef typename iterator_traits<_II2>::iterator_category _Category2;
 874         typedef std::__lc_rai<_Category1, _Category2>   __rai_type;
 875
 876         __last1 = __rai_type::__newlast1(__first1, __last1,
 877                                          __first2, __last2);
 878         for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
 879              ++__first1, ++__first2)
 880           {
 881             if (*__first1 < *__first2)
 882               return true;
 883             if (*__first2 < *__first1)
 884               return false;
 885           }
 886         return __first1 == __last1 && __first2 != __last2;
 887       }
 888
 889   template<>
 890     struct __lexicographical_compare<true>
 891     {
 892       template<typename _Tp, typename _Up>
 893         static bool
 894         __lc(const _Tp* __first1, const _Tp* __last1,
 895              const _Up* __first2, const _Up* __last2)
 896         {
 897           const size_t __len1 = __last1 - __first1;
 898           const size_t __len2 = __last2 - __first2;
 899           const int __result = __builtin_memcmp(__first1, __first2,
 900                                                 std::min(__len1, __len2));
 901           return __result != 0 ? __result < 0 : __len1 < __len2;
 902         }
 903     };
 904
 905   template<typename _II1, typename _II2>
 906     inline bool
 907     __lexicographical_compare_aux(_II1 __first1, _II1 __last1,
 908                                   _II2 __first2, _II2 __last2)
 909     {
 910       typedef typename iterator_traits<_II1>::value_type _ValueType1;
 911       typedef typename iterator_traits<_II2>::value_type _ValueType2;
 912       const bool __simple =
 913         (__is_byte<_ValueType1>::__value && __is_byte<_ValueType2>::__value
 914          && !__gnu_cxx::__numeric_traits<_ValueType1>::__is_signed
 915          && !__gnu_cxx::__numeric_traits<_ValueType2>::__is_signed
 916          && __is_pointer<_II1>::__value
 917          && __is_pointer<_II2>::__value);
 918
 919       return std::__lexicographical_compare<__simple>::__lc(__first1, __last1,
 920                                                             __first2, __last2);
 921     }
 922
 923   /**
 924    *  @brief Finds the first position in which @a val could be inserted
 925    *         without changing the ordering.
 926    *  @param  first   An iterator.
 927    *  @param  last    Another iterator.
 928    *  @param  val     The search term.
 929    *  @return         An iterator pointing to the first element <em>not less
 930    *                  than</em> @a val, or end() if every element is less than
 931    *                  @a val.
 932    *  @ingroup binary_search_algorithms
 933   */
 934   template<typename _ForwardIterator, typename _Tp>
 935     _ForwardIterator
 936     lower_bound(_ForwardIterator __first, _ForwardIterator __last,
 937                 const _Tp& __val)
 938     {
 939       typedef typename iterator_traits<_ForwardIterator>::value_type
 940         _ValueType;
 941       typedef typename iterator_traits<_ForwardIterator>::difference_type
 942         _DistanceType;
 943
 944       // concept requirements
 945       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
 946       __glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
 947       __glibcxx_requires_partitioned_lower(__first, __last, __val);
 948
 949       _DistanceType __len = std::distance(__first, __last);
 950
 951       while (__len > 0)
 952         {
 953           _DistanceType __half = __len >> 1;
 954           _ForwardIterator __middle = __first;
 955           std::advance(__middle, __half);
 956           if (*__middle < __val)
 957             {
 958               __first = __middle;
 959               ++__first;
 960               __len = __len - __half - 1;
 961             }
 962           else
 963             __len = __half;
 964         }
 965       return __first;
 966     }
 967
 968   /// This is a helper function for the sort routines and for random.tcc.
 969   //  Precondition: __n > 0.
 970   template<typename _Size>
 971     inline _Size
 972     __lg(_Size __n)
 973     {
 974       _Size __k;
 975       for (__k = 0; __n != 0; __n >>= 1)
 976         ++__k;
 977       return __k - 1;
 978     }
 979
 980   inline int
 981   __lg(int __n)
 982   { return sizeof(int) * __CHAR_BIT__  - 1 - __builtin_clz(__n); }
 983
 984   inline long
 985   __lg(long __n)
 986   { return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
 987
 988   inline long long
 989   __lg(long long __n)
 990   { return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
 991
 992 _GLIBCXX_END_NAMESPACE_VERSION
 993
 994 _GLIBCXX_BEGIN_NAMESPACE_ALGO
 995
 996   /**
 997    *  @brief Tests a range for element-wise equality.
 998    *  @ingroup non_mutating_algorithms
 999    *  @param  first1  An input iterator.
1000    *  @param  last1   An input iterator.
1001    *  @param  first2  An input iterator.
1002    *  @return   A boolean true or false.
1003    *
1004    *  This compares the elements of two ranges using @c == and returns true or
1005    *  false depending on whether all of the corresponding elements of the
1006    *  ranges are equal.
1007   */
1008   template<typename _II1, typename _II2>
1009     inline bool
1010     equal(_II1 __first1, _II1 __last1, _II2 __first2)
1011     {
1012       // concept requirements
1013       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1014       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1015       __glibcxx_function_requires(_EqualOpConcept<
1016             typename iterator_traits<_II1>::value_type,
1017             typename iterator_traits<_II2>::value_type>)
1018       __glibcxx_requires_valid_range(__first1, __last1);
1019
1020       return std::__equal_aux(std::__niter_base(__first1),
1021                               std::__niter_base(__last1),
1022                               std::__niter_base(__first2));
1023     }
1024
1025   /**
1026    *  @brief Tests a range for element-wise equality.
1027    *  @ingroup non_mutating_algorithms
1028    *  @param  first1  An input iterator.
1029    *  @param  last1   An input iterator.
1030    *  @param  first2  An input iterator.
1031    *  @param binary_pred A binary predicate @link functors
1032    *                  functor@endlink.
1033    *  @return         A boolean true or false.
1034    *
1035    *  This compares the elements of two ranges using the binary_pred
1036    *  parameter, and returns true or
1037    *  false depending on whether all of the corresponding elements of the
1038    *  ranges are equal.
1039   */
1040   template<typename _IIter1, typename _IIter2, typename _BinaryPredicate>
1041     inline bool
1042     equal(_IIter1 __first1, _IIter1 __last1,
1043           _IIter2 __first2, _BinaryPredicate __binary_pred)
1044     {
1045       // concept requirements
1046       __glibcxx_function_requires(_InputIteratorConcept<_IIter1>)
1047       __glibcxx_function_requires(_InputIteratorConcept<_IIter2>)
1048       __glibcxx_requires_valid_range(__first1, __last1);
1049
1050       for (; __first1 != __last1; ++__first1, ++__first2)
1051         if (!bool(__binary_pred(*__first1, *__first2)))
1052           return false;
1053       return true;
1054     }
1055
1056   /**
1057    *  @brief Performs @b dictionary comparison on ranges.
1058    *  @ingroup sorting_algorithms
1059    *  @param  first1  An input iterator.
1060    *  @param  last1   An input iterator.
1061    *  @param  first2  An input iterator.
1062    *  @param  last2   An input iterator.
1063    *  @return   A boolean true or false.
1064    *
1065    *  <em>Returns true if the sequence of elements defined by the range
1066    *  [first1,last1) is lexicographically less than the sequence of elements
1067    *  defined by the range [first2,last2).  Returns false otherwise.</em>
1068    *  (Quoted from [25.3.8]/1.)  If the iterators are all character pointers,
1069    *  then this is an inline call to @c memcmp.
1070   */
1071   template<typename _II1, typename _II2>
1072     inline bool
1073     lexicographical_compare(_II1 __first1, _II1 __last1,
1074                             _II2 __first2, _II2 __last2)
1075     {
1076       // concept requirements
1077       typedef typename iterator_traits<_II1>::value_type _ValueType1;
1078       typedef typename iterator_traits<_II2>::value_type _ValueType2;
1079       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1080       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1081       __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
1082       __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
1083       __glibcxx_requires_valid_range(__first1, __last1);
1084       __glibcxx_requires_valid_range(__first2, __last2);
1085
1086       return std::__lexicographical_compare_aux(std::__niter_base(__first1),
1087                                                 std::__niter_base(__last1),
1088                                                 std::__niter_base(__first2),
1089                                                 std::__niter_base(__last2));
1090     }
1091
1092   /**
1093    *  @brief Performs @b dictionary comparison on ranges.
1094    *  @ingroup sorting_algorithms
1095    *  @param  first1  An input iterator.
1096    *  @param  last1   An input iterator.
1097    *  @param  first2  An input iterator.
1098    *  @param  last2   An input iterator.
1099    *  @param  comp  A @link comparison_functors comparison functor@endlink.
1100    *  @return   A boolean true or false.
1101    *
1102    *  The same as the four-parameter @c lexicographical_compare, but uses the
1103    *  comp parameter instead of @c <.
1104   */
1105   template<typename _II1, typename _II2, typename _Compare>
1106     bool
1107     lexicographical_compare(_II1 __first1, _II1 __last1,
1108                             _II2 __first2, _II2 __last2, _Compare __comp)
1109     {
1110       typedef typename iterator_traits<_II1>::iterator_category _Category1;
1111       typedef typename iterator_traits<_II2>::iterator_category _Category2;
1112       typedef std::__lc_rai<_Category1, _Category2>     __rai_type;
1113
1114       // concept requirements
1115       __glibcxx_function_requires(_InputIteratorConcept<_II1>)
1116       __glibcxx_function_requires(_InputIteratorConcept<_II2>)
1117       __glibcxx_requires_valid_range(__first1, __last1);
1118       __glibcxx_requires_valid_range(__first2, __last2);
1119
1120       __last1 = __rai_type::__newlast1(__first1, __last1, __first2, __last2);
1121       for (; __first1 != __last1 && __rai_type::__cnd2(__first2, __last2);
1122            ++__first1, ++__first2)
1123         {
1124           if (__comp(*__first1, *__first2))
1125             return true;
1126           if (__comp(*__first2, *__first1))
1127             return false;
1128         }
1129       return __first1 == __last1 && __first2 != __last2;
1130     }
1131
1132   /**
1133    *  @brief Finds the places in ranges which don't match.
1134    *  @ingroup non_mutating_algorithms
1135    *  @param  first1  An input iterator.
1136    *  @param  last1   An input iterator.
1137    *  @param  first2  An input iterator.
1138    *  @return   A pair of iterators pointing to the first mismatch.
1139    *
1140    *  This compares the elements of two ranges using @c == and returns a pair
1141    *  of iterators.  The first iterator points into the first range, the
1142    *  second iterator points into the second range, and the elements pointed
1143    *  to by the iterators are not equal.
1144   */
1145   template<typename _InputIterator1, typename _InputIterator2>
1146     pair<_InputIterator1, _InputIterator2>
1147     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1148              _InputIterator2 __first2)
1149     {
1150       // concept requirements
1151       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1152       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1153       __glibcxx_function_requires(_EqualOpConcept<
1154             typename iterator_traits<_InputIterator1>::value_type,
1155             typename iterator_traits<_InputIterator2>::value_type>)
1156       __glibcxx_requires_valid_range(__first1, __last1);
1157
1158       while (__first1 != __last1 && *__first1 == *__first2)
1159         {
1160           ++__first1;
1161           ++__first2;
1162         }
1163       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1164     }
1165
1166   /**
1167    *  @brief Finds the places in ranges which don't match.
1168    *  @ingroup non_mutating_algorithms
1169    *  @param  first1  An input iterator.
1170    *  @param  last1   An input iterator.
1171    *  @param  first2  An input iterator.
1172    *  @param binary_pred A binary predicate @link functors
1173    *         functor@endlink.
1174    *  @return   A pair of iterators pointing to the first mismatch.
1175    *
1176    *  This compares the elements of two ranges using the binary_pred
1177    *  parameter, and returns a pair
1178    *  of iterators.  The first iterator points into the first range, the
1179    *  second iterator points into the second range, and the elements pointed
1180    *  to by the iterators are not equal.
1181   */
1182   template<typename _InputIterator1, typename _InputIterator2,
1183            typename _BinaryPredicate>
1184     pair<_InputIterator1, _InputIterator2>
1185     mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1186              _InputIterator2 __first2, _BinaryPredicate __binary_pred)
1187     {
1188       // concept requirements
1189       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
1190       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
1191       __glibcxx_requires_valid_range(__first1, __last1);
1192
1193       while (__first1 != __last1 && bool(__binary_pred(*__first1, *__first2)))
1194         {
1195           ++__first1;
1196           ++__first2;
1197         }
1198       return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1199     }
1200
1201 _GLIBCXX_END_NAMESPACE_ALGO
1202 } // namespace std
1203
1204 // NB: This file is included within many other C++ includes, as a way
1205 // of getting the base algorithms. So, make sure that parallel bits
1206 // come in too if requested.
1207 #ifdef _GLIBCXX_PARALLEL
1208 # include <parallel/algobase.h>
1209 #endif
1210
1211 #endif