libstdc++-v3/include/parallel/algo.h

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2007-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 3, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file parallel/algo.h
  26  *  @brief Parallel STL function calls corresponding to the stl_algo.h header.
  27  *
  28  *  The functions defined here mainly do case switches and
  29  *  call the actual parallelized versions in other files.
  30  *  Inlining policy: Functions that basically only contain one function call,
  31  *  are declared inline.
  32  *  This file is a GNU parallel extension to the Standard C++ Library.
  33  */
  34
  35 // Written by Johannes Singler and Felix Putze.
  36
  37 #ifndef _GLIBCXX_PARALLEL_ALGO_H
  38 #define _GLIBCXX_PARALLEL_ALGO_H 1
  39
  40 #include <parallel/algorithmfwd.h>
  41 #include <bits/stl_algobase.h>
  42 #include <bits/stl_algo.h>
  43 #include <parallel/iterator.h>
  44 #include <parallel/base.h>
  45 #include <parallel/sort.h>
  46 #include <parallel/workstealing.h>
  47 #include <parallel/par_loop.h>
  48 #include <parallel/omp_loop.h>
  49 #include <parallel/omp_loop_static.h>
  50 #include <parallel/for_each_selectors.h>
  51 #include <parallel/for_each.h>
  52 #include <parallel/find.h>
  53 #include <parallel/find_selectors.h>
  54 #include <parallel/search.h>
  55 #include <parallel/random_shuffle.h>
  56 #include <parallel/partition.h>
  57 #include <parallel/merge.h>
  58 #include <parallel/unique_copy.h>
  59 #include <parallel/set_operations.h>
  60
  61 namespace std _GLIBCXX_VISIBILITY(default)
  62 {
  63 namespace __parallel
  64 {
  65   // Sequential fallback
  66   template<typename _IIter, typename _Function>
  67     inline _Function
  68     for_each(_IIter __begin, _IIter __end, _Function __f,
  69              __gnu_parallel::sequential_tag)
  70     { return _GLIBCXX_STD_A::for_each(__begin, __end, __f); }
  71
  72   // Sequential fallback for input iterator case
  73   template<typename _IIter, typename _Function, typename _IteratorTag>
  74     inline _Function
  75     __for_each_switch(_IIter __begin, _IIter __end, _Function __f,
  76                       _IteratorTag)
  77     { return for_each(__begin, __end, __f, __gnu_parallel::sequential_tag()); }
  78
  79   // Parallel algorithm for random access iterators
  80   template<typename _RAIter, typename _Function>
  81     _Function
  82     __for_each_switch(_RAIter __begin, _RAIter __end,
  83                       _Function __f, random_access_iterator_tag,
  84                       __gnu_parallel::_Parallelism __parallelism_tag)
  85     {
  86       if (_GLIBCXX_PARALLEL_CONDITION(
  87             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
  88             >= __gnu_parallel::_Settings::get().for_each_minimal_n
  89             && __gnu_parallel::__is_parallel(__parallelism_tag)))
  90         {
  91           bool __dummy;
  92           __gnu_parallel::__for_each_selector<_RAIter> __functionality;
  93
  94           return __gnu_parallel::
  95             __for_each_template_random_access(
  96               __begin, __end, __f, __functionality,
  97               __gnu_parallel::_DummyReduct(), true, __dummy, -1,
  98               __parallelism_tag);
  99         }
 100       else
 101         return for_each(__begin, __end, __f, __gnu_parallel::sequential_tag());
 102     }
 103
 104   // Public interface
 105   template<typename _Iterator, typename _Function>
 106     inline _Function
 107     for_each(_Iterator __begin, _Iterator __end, _Function __f,
 108              __gnu_parallel::_Parallelism __parallelism_tag)
 109     {
 110       return __for_each_switch(__begin, __end, __f,
 111                                std::__iterator_category(__begin),
 112                                __parallelism_tag);
 113     }
 114
 115   template<typename _Iterator, typename _Function>
 116     inline _Function
 117     for_each(_Iterator __begin, _Iterator __end, _Function __f)
 118     {
 119       return __for_each_switch(__begin, __end, __f,
 120                                std::__iterator_category(__begin));
 121     }
 122
 123   // Sequential fallback
 124   template<typename _IIter, typename _Tp>
 125     inline _IIter
 126     find(_IIter __begin, _IIter __end, const _Tp& __val,
 127          __gnu_parallel::sequential_tag)
 128     { return _GLIBCXX_STD_A::find(__begin, __end, __val); }
 129
 130   // Sequential fallback for input iterator case
 131   template<typename _IIter, typename _Tp, typename _IteratorTag>
 132     inline _IIter
 133     __find_switch(_IIter __begin, _IIter __end, const _Tp& __val,
 134                 _IteratorTag)
 135     { return _GLIBCXX_STD_A::find(__begin, __end, __val); }
 136
 137   // Parallel find for random access iterators
 138   template<typename _RAIter, typename _Tp>
 139     _RAIter
 140     __find_switch(_RAIter __begin, _RAIter __end,
 141                 const _Tp& __val, random_access_iterator_tag)
 142     {
 143       typedef iterator_traits<_RAIter> _TraitsType;
 144       typedef typename _TraitsType::value_type _ValueType;
 145
 146       if (_GLIBCXX_PARALLEL_CONDITION(true))
 147         {
 148           __gnu_parallel::__binder2nd<__gnu_parallel::_EqualTo<_ValueType,
 149                                                                const _Tp&>,
 150                                       _ValueType, const _Tp&, bool>
 151             __comp(__gnu_parallel::_EqualTo<_ValueType, const _Tp&>(), __val);
 152           return __gnu_parallel::__find_template(
 153                    __begin, __end, __begin, __comp,
 154                    __gnu_parallel::__find_if_selector()).first;
 155         }
 156       else
 157         return _GLIBCXX_STD_A::find(__begin, __end, __val);
 158     }
 159
 160   // Public interface
 161   template<typename _IIter, typename _Tp>
 162     inline _IIter
 163     find(_IIter __begin, _IIter __end, const _Tp& __val)
 164     {
 165       return __find_switch(__begin, __end, __val,
 166                            std::__iterator_category(__begin));
 167     }
 168
 169   // Sequential fallback
 170   template<typename _IIter, typename _Predicate>
 171     inline _IIter
 172     find_if(_IIter __begin, _IIter __end, _Predicate __pred,
 173             __gnu_parallel::sequential_tag)
 174     { return _GLIBCXX_STD_A::find_if(__begin, __end, __pred); }
 175
 176   // Sequential fallback for input iterator case
 177   template<typename _IIter, typename _Predicate, typename _IteratorTag>
 178     inline _IIter
 179     __find_if_switch(_IIter __begin, _IIter __end, _Predicate __pred,
 180                    _IteratorTag)
 181     { return _GLIBCXX_STD_A::find_if(__begin, __end, __pred); }
 182
 183   // Parallel find_if for random access iterators
 184   template<typename _RAIter, typename _Predicate>
 185     _RAIter
 186     __find_if_switch(_RAIter __begin, _RAIter __end,
 187                    _Predicate __pred, random_access_iterator_tag)
 188     {
 189       if (_GLIBCXX_PARALLEL_CONDITION(true))
 190         return __gnu_parallel::__find_template(__begin, __end, __begin, __pred,
 191                                              __gnu_parallel::
 192                                              __find_if_selector()).first;
 193       else
 194         return _GLIBCXX_STD_A::find_if(__begin, __end, __pred);
 195     }
 196
 197   // Public interface
 198   template<typename _IIter, typename _Predicate>
 199     inline _IIter
 200     find_if(_IIter __begin, _IIter __end, _Predicate __pred)
 201     {
 202       return __find_if_switch(__begin, __end, __pred,
 203                               std::__iterator_category(__begin));
 204     }
 205
 206   // Sequential fallback
 207   template<typename _IIter, typename _FIterator>
 208     inline _IIter
 209     find_first_of(_IIter __begin1, _IIter __end1,
 210                   _FIterator __begin2, _FIterator __end2,
 211                   __gnu_parallel::sequential_tag)
 212     {
 213       return _GLIBCXX_STD_A::find_first_of(__begin1, __end1, __begin2, __end2);
 214     }
 215
 216   // Sequential fallback
 217   template<typename _IIter, typename _FIterator,
 218            typename _BinaryPredicate>
 219     inline _IIter
 220     find_first_of(_IIter __begin1, _IIter __end1,
 221                   _FIterator __begin2, _FIterator __end2,
 222                   _BinaryPredicate __comp, __gnu_parallel::sequential_tag)
 223   { return _GLIBCXX_STD_A::find_first_of(
 224              __begin1, __end1, __begin2, __end2, __comp); }
 225
 226   // Sequential fallback for input iterator type
 227   template<typename _IIter, typename _FIterator,
 228            typename _IteratorTag1, typename _IteratorTag2>
 229     inline _IIter
 230     __find_first_of_switch(_IIter __begin1, _IIter __end1,
 231                            _FIterator __begin2, _FIterator __end2,
 232                            _IteratorTag1, _IteratorTag2)
 233     { return find_first_of(__begin1, __end1, __begin2, __end2,
 234                            __gnu_parallel::sequential_tag()); }
 235
 236   // Parallel algorithm for random access iterators
 237   template<typename _RAIter, typename _FIterator,
 238            typename _BinaryPredicate, typename _IteratorTag>
 239     inline _RAIter
 240     __find_first_of_switch(_RAIter __begin1,
 241                            _RAIter __end1,
 242                            _FIterator __begin2, _FIterator __end2,
 243                            _BinaryPredicate __comp, random_access_iterator_tag,
 244                            _IteratorTag)
 245     {
 246       return __gnu_parallel::
 247         __find_template(__begin1, __end1, __begin1, __comp,
 248                       __gnu_parallel::__find_first_of_selector
 249                       <_FIterator>(__begin2, __end2)).first;
 250     }
 251
 252   // Sequential fallback for input iterator type
 253   template<typename _IIter, typename _FIterator,
 254            typename _BinaryPredicate, typename _IteratorTag1,
 255            typename _IteratorTag2>
 256     inline _IIter
 257     __find_first_of_switch(_IIter __begin1, _IIter __end1,
 258                            _FIterator __begin2, _FIterator __end2,
 259                            _BinaryPredicate __comp, _IteratorTag1, _IteratorTag2)
 260     { return find_first_of(__begin1, __end1, __begin2, __end2, __comp,
 261                            __gnu_parallel::sequential_tag()); }
 262
 263   // Public interface
 264   template<typename _IIter, typename _FIterator,
 265            typename _BinaryPredicate>
 266     inline _IIter
 267     find_first_of(_IIter __begin1, _IIter __end1,
 268                   _FIterator __begin2, _FIterator __end2,
 269                   _BinaryPredicate __comp)
 270     {
 271       return __find_first_of_switch(__begin1, __end1, __begin2, __end2, __comp,
 272                                     std::__iterator_category(__begin1),
 273                                     std::__iterator_category(__begin2));
 274     }
 275
 276   // Public interface, insert default comparator
 277   template<typename _IIter, typename _FIterator>
 278     inline _IIter
 279     find_first_of(_IIter __begin1, _IIter __end1,
 280                   _FIterator __begin2, _FIterator __end2)
 281     {
 282       typedef typename std::iterator_traits<_IIter>::value_type _IValueType;
 283       typedef typename std::iterator_traits<_FIterator>::value_type _FValueType;
 284
 285       return __gnu_parallel::find_first_of(__begin1, __end1, __begin2, __end2,
 286                          __gnu_parallel::_EqualTo<_IValueType, _FValueType>());
 287     }
 288
 289   // Sequential fallback
 290   template<typename _IIter, typename _OutputIterator>
 291     inline _OutputIterator
 292     unique_copy(_IIter __begin1, _IIter __end1, _OutputIterator __out,
 293                 __gnu_parallel::sequential_tag)
 294     { return _GLIBCXX_STD_A::unique_copy(__begin1, __end1, __out); }
 295
 296   // Sequential fallback
 297   template<typename _IIter, typename _OutputIterator,
 298            typename _Predicate>
 299     inline _OutputIterator
 300     unique_copy(_IIter __begin1, _IIter __end1, _OutputIterator __out,
 301                 _Predicate __pred, __gnu_parallel::sequential_tag)
 302     { return _GLIBCXX_STD_A::unique_copy(__begin1, __end1, __out, __pred); }
 303
 304   // Sequential fallback for input iterator case
 305   template<typename _IIter, typename _OutputIterator,
 306            typename _Predicate, typename _IteratorTag1, typename _IteratorTag2>
 307     inline _OutputIterator
 308     __unique_copy_switch(_IIter __begin, _IIter __last,
 309                        _OutputIterator __out, _Predicate __pred,
 310                        _IteratorTag1, _IteratorTag2)
 311     { return _GLIBCXX_STD_A::unique_copy(__begin, __last, __out, __pred); }
 312
 313   // Parallel unique_copy for random access iterators
 314   template<typename _RAIter, typename _RandomAccessOutputIterator,
 315            typename _Predicate>
 316     _RandomAccessOutputIterator
 317     __unique_copy_switch(_RAIter __begin, _RAIter __last,
 318                          _RandomAccessOutputIterator __out, _Predicate __pred,
 319                          random_access_iterator_tag, random_access_iterator_tag)
 320     {
 321       if (_GLIBCXX_PARALLEL_CONDITION(
 322             static_cast<__gnu_parallel::_SequenceIndex>(__last - __begin)
 323             > __gnu_parallel::_Settings::get().unique_copy_minimal_n))
 324         return __gnu_parallel::__parallel_unique_copy(
 325                  __begin, __last, __out, __pred);
 326       else
 327         return _GLIBCXX_STD_A::unique_copy(__begin, __last, __out, __pred);
 328     }
 329
 330   // Public interface
 331   template<typename _IIter, typename _OutputIterator>
 332     inline _OutputIterator
 333     unique_copy(_IIter __begin1, _IIter __end1, _OutputIterator __out)
 334     {
 335       typedef typename std::iterator_traits<_IIter>::value_type _ValueType;
 336
 337       return __unique_copy_switch(
 338                __begin1, __end1, __out, equal_to<_ValueType>(),
 339                std::__iterator_category(__begin1),
 340                std::__iterator_category(__out));
 341     }
 342
 343   // Public interface
 344   template<typename _IIter, typename _OutputIterator, typename _Predicate>
 345     inline _OutputIterator
 346     unique_copy(_IIter __begin1, _IIter __end1, _OutputIterator __out,
 347                 _Predicate __pred)
 348     {
 349       return __unique_copy_switch(
 350                __begin1, __end1, __out, __pred,
 351                std::__iterator_category(__begin1),
 352                std::__iterator_category(__out));
 353     }
 354
 355   // Sequential fallback
 356   template<typename _IIter1, typename _IIter2,
 357            typename _OutputIterator>
 358     inline _OutputIterator
 359     set_union(_IIter1 __begin1, _IIter1 __end1,
 360               _IIter2 __begin2, _IIter2 __end2,
 361               _OutputIterator __out, __gnu_parallel::sequential_tag)
 362     { return _GLIBCXX_STD_A::set_union(
 363                __begin1, __end1, __begin2, __end2, __out); }
 364
 365   // Sequential fallback
 366   template<typename _IIter1, typename _IIter2,
 367            typename _OutputIterator, typename _Predicate>
 368     inline _OutputIterator
 369     set_union(_IIter1 __begin1, _IIter1 __end1,
 370               _IIter2 __begin2, _IIter2 __end2,
 371               _OutputIterator __out, _Predicate __pred,
 372               __gnu_parallel::sequential_tag)
 373     { return _GLIBCXX_STD_A::set_union(__begin1, __end1,
 374                                        __begin2, __end2, __out, __pred); }
 375
 376   // Sequential fallback for input iterator case
 377   template<typename _IIter1, typename _IIter2, typename _Predicate,
 378            typename _OutputIterator, typename _IteratorTag1,
 379            typename _IteratorTag2, typename _IteratorTag3>
 380     inline _OutputIterator
 381     __set_union_switch(
 382       _IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2, _IIter2 __end2,
 383       _OutputIterator __result, _Predicate __pred,
 384       _IteratorTag1, _IteratorTag2, _IteratorTag3)
 385     { return _GLIBCXX_STD_A::set_union(__begin1, __end1,
 386                                        __begin2, __end2, __result, __pred); }
 387
 388   // Parallel set_union for random access iterators
 389   template<typename _RAIter1, typename _RAIter2,
 390            typename _Output_RAIter, typename _Predicate>
 391     _Output_RAIter
 392     __set_union_switch(_RAIter1 __begin1, _RAIter1 __end1,
 393                        _RAIter2 __begin2, _RAIter2 __end2,
 394                        _Output_RAIter __result, _Predicate __pred,
 395                        random_access_iterator_tag, random_access_iterator_tag,
 396                        random_access_iterator_tag)
 397     {
 398       if (_GLIBCXX_PARALLEL_CONDITION(
 399             static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
 400             >= __gnu_parallel::_Settings::get().set_union_minimal_n
 401             || static_cast<__gnu_parallel::_SequenceIndex>(__end2 - __begin2)
 402             >= __gnu_parallel::_Settings::get().set_union_minimal_n))
 403         return __gnu_parallel::__parallel_set_union(
 404                  __begin1, __end1, __begin2, __end2, __result, __pred);
 405       else
 406         return _GLIBCXX_STD_A::set_union(__begin1, __end1,
 407                                          __begin2, __end2, __result, __pred);
 408     }
 409
 410   // Public interface
 411   template<typename _IIter1, typename _IIter2,
 412            typename _OutputIterator>
 413     inline _OutputIterator
 414     set_union(_IIter1 __begin1, _IIter1 __end1,
 415               _IIter2 __begin2, _IIter2 __end2, _OutputIterator __out)
 416     {
 417       typedef typename std::iterator_traits<_IIter1>::value_type _ValueType1;
 418       typedef typename std::iterator_traits<_IIter2>::value_type _ValueType2;
 419
 420       return __set_union_switch(
 421                __begin1, __end1, __begin2, __end2, __out,
 422                __gnu_parallel::_Less<_ValueType1, _ValueType2>(),
 423                std::__iterator_category(__begin1),
 424                std::__iterator_category(__begin2),
 425                std::__iterator_category(__out));
 426     }
 427
 428   // Public interface
 429   template<typename _IIter1, typename _IIter2,
 430            typename _OutputIterator, typename _Predicate>
 431     inline _OutputIterator
 432     set_union(_IIter1 __begin1, _IIter1 __end1,
 433               _IIter2 __begin2, _IIter2 __end2,
 434               _OutputIterator __out, _Predicate __pred)
 435     {
 436       return __set_union_switch(
 437                __begin1, __end1, __begin2, __end2, __out, __pred,
 438                std::__iterator_category(__begin1),
 439                std::__iterator_category(__begin2),
 440                std::__iterator_category(__out));
 441     }
 442
 443   // Sequential fallback.
 444   template<typename _IIter1, typename _IIter2,
 445            typename _OutputIterator>
 446     inline _OutputIterator
 447     set_intersection(_IIter1 __begin1, _IIter1 __end1,
 448                      _IIter2 __begin2, _IIter2 __end2,
 449                      _OutputIterator __out, __gnu_parallel::sequential_tag)
 450     { return _GLIBCXX_STD_A::set_intersection(__begin1, __end1,
 451                                               __begin2, __end2, __out); }
 452
 453   // Sequential fallback.
 454   template<typename _IIter1, typename _IIter2,
 455            typename _OutputIterator, typename _Predicate>
 456     inline _OutputIterator
 457     set_intersection(_IIter1 __begin1, _IIter1 __end1,
 458                      _IIter2 __begin2, _IIter2 __end2,
 459                      _OutputIterator __out, _Predicate __pred,
 460                      __gnu_parallel::sequential_tag)
 461     { return _GLIBCXX_STD_A::set_intersection(
 462                __begin1, __end1, __begin2, __end2, __out, __pred); }
 463
 464   // Sequential fallback for input iterator case
 465   template<typename _IIter1, typename _IIter2,
 466            typename _Predicate, typename _OutputIterator,
 467            typename _IteratorTag1, typename _IteratorTag2,
 468            typename _IteratorTag3>
 469     inline _OutputIterator
 470     __set_intersection_switch(_IIter1 __begin1, _IIter1 __end1,
 471                               _IIter2 __begin2, _IIter2 __end2,
 472                               _OutputIterator __result, _Predicate __pred,
 473                               _IteratorTag1, _IteratorTag2, _IteratorTag3)
 474     { return _GLIBCXX_STD_A::set_intersection(__begin1, __end1, __begin2,
 475                                               __end2, __result, __pred); }
 476
 477   // Parallel set_intersection for random access iterators
 478   template<typename _RAIter1, typename _RAIter2,
 479            typename _Output_RAIter, typename _Predicate>
 480     _Output_RAIter
 481     __set_intersection_switch(_RAIter1 __begin1,
 482                               _RAIter1 __end1,
 483                               _RAIter2 __begin2,
 484                               _RAIter2 __end2,
 485                               _Output_RAIter __result,
 486                               _Predicate __pred,
 487                               random_access_iterator_tag,
 488                               random_access_iterator_tag,
 489                               random_access_iterator_tag)
 490     {
 491       if (_GLIBCXX_PARALLEL_CONDITION(
 492             static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
 493             >= __gnu_parallel::_Settings::get().set_union_minimal_n
 494             || static_cast<__gnu_parallel::_SequenceIndex>(__end2 - __begin2)
 495             >= __gnu_parallel::_Settings::get().set_union_minimal_n))
 496         return __gnu_parallel::__parallel_set_intersection(
 497                  __begin1, __end1, __begin2, __end2, __result, __pred);
 498       else
 499         return _GLIBCXX_STD_A::set_intersection(
 500                  __begin1, __end1, __begin2, __end2, __result, __pred);
 501     }
 502
 503   // Public interface
 504   template<typename _IIter1, typename _IIter2,
 505            typename _OutputIterator>
 506     inline _OutputIterator
 507     set_intersection(_IIter1 __begin1, _IIter1 __end1,
 508                      _IIter2 __begin2, _IIter2 __end2,
 509                      _OutputIterator __out)
 510     {
 511       typedef typename std::iterator_traits<_IIter1>::value_type _ValueType1;
 512       typedef typename std::iterator_traits<_IIter2>::value_type _ValueType2;
 513
 514       return __set_intersection_switch(
 515                __begin1, __end1, __begin2, __end2, __out,
 516                __gnu_parallel::_Less<_ValueType1, _ValueType2>(),
 517                std::__iterator_category(__begin1),
 518                std::__iterator_category(__begin2),
 519                std::__iterator_category(__out));
 520     }
 521
 522   template<typename _IIter1, typename _IIter2,
 523            typename _OutputIterator, typename _Predicate>
 524     inline _OutputIterator
 525     set_intersection(_IIter1 __begin1, _IIter1 __end1,
 526                      _IIter2 __begin2, _IIter2 __end2,
 527                      _OutputIterator __out, _Predicate __pred)
 528     {
 529       return __set_intersection_switch(
 530                __begin1, __end1, __begin2, __end2, __out, __pred,
 531                std::__iterator_category(__begin1),
 532                std::__iterator_category(__begin2),
 533                std::__iterator_category(__out));
 534     }
 535
 536   // Sequential fallback
 537   template<typename _IIter1, typename _IIter2,
 538            typename _OutputIterator>
 539     inline _OutputIterator
 540     set_symmetric_difference(_IIter1 __begin1, _IIter1 __end1,
 541                              _IIter2 __begin2, _IIter2 __end2,
 542                              _OutputIterator __out,
 543                              __gnu_parallel::sequential_tag)
 544     { return _GLIBCXX_STD_A::set_symmetric_difference(
 545                __begin1, __end1, __begin2, __end2, __out); }
 546
 547   // Sequential fallback
 548   template<typename _IIter1, typename _IIter2,
 549            typename _OutputIterator, typename _Predicate>
 550     inline _OutputIterator
 551     set_symmetric_difference(_IIter1 __begin1, _IIter1 __end1,
 552                              _IIter2 __begin2, _IIter2 __end2,
 553                              _OutputIterator __out, _Predicate __pred,
 554                              __gnu_parallel::sequential_tag)
 555     { return _GLIBCXX_STD_A::set_symmetric_difference(
 556                __begin1, __end1, __begin2, __end2, __out, __pred); }
 557
 558   // Sequential fallback for input iterator case
 559   template<typename _IIter1, typename _IIter2,
 560            typename _Predicate, typename _OutputIterator,
 561            typename _IteratorTag1, typename _IteratorTag2,
 562            typename _IteratorTag3>
 563     inline _OutputIterator
 564     __set_symmetric_difference_switch(
 565         _IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2, _IIter2 __end2,
 566         _OutputIterator __result, _Predicate __pred,
 567         _IteratorTag1, _IteratorTag2, _IteratorTag3)
 568     { return _GLIBCXX_STD_A::set_symmetric_difference(
 569                __begin1, __end1, __begin2, __end2, __result, __pred); }
 570
 571   // Parallel set_symmetric_difference for random access iterators
 572   template<typename _RAIter1, typename _RAIter2,
 573            typename _Output_RAIter, typename _Predicate>
 574     _Output_RAIter
 575     __set_symmetric_difference_switch(_RAIter1 __begin1,
 576                                       _RAIter1 __end1,
 577                                       _RAIter2 __begin2,
 578                                       _RAIter2 __end2,
 579                                       _Output_RAIter __result,
 580                                       _Predicate __pred,
 581                                       random_access_iterator_tag,
 582                                       random_access_iterator_tag,
 583                                       random_access_iterator_tag)
 584     {
 585       if (_GLIBCXX_PARALLEL_CONDITION(
 586       static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
 587       >= __gnu_parallel::_Settings::get().set_symmetric_difference_minimal_n
 588       || static_cast<__gnu_parallel::_SequenceIndex>(__end2 - __begin2)
 589       >= __gnu_parallel::_Settings::get().set_symmetric_difference_minimal_n))
 590   return __gnu_parallel::__parallel_set_symmetric_difference(
 591            __begin1, __end1, __begin2, __end2, __result, __pred);
 592       else
 593         return _GLIBCXX_STD_A::set_symmetric_difference(
 594                  __begin1, __end1, __begin2, __end2, __result, __pred);
 595     }
 596
 597   // Public interface.
 598   template<typename _IIter1, typename _IIter2,
 599            typename _OutputIterator>
 600     inline _OutputIterator
 601     set_symmetric_difference(_IIter1 __begin1, _IIter1 __end1,
 602                              _IIter2 __begin2, _IIter2 __end2,
 603                              _OutputIterator __out)
 604     {
 605       typedef typename std::iterator_traits<_IIter1>::value_type _ValueType1;
 606       typedef typename std::iterator_traits<_IIter2>::value_type _ValueType2;
 607
 608       return __set_symmetric_difference_switch(
 609                __begin1, __end1, __begin2, __end2, __out,
 610                __gnu_parallel::_Less<_ValueType1, _ValueType2>(),
 611                std::__iterator_category(__begin1),
 612                std::__iterator_category(__begin2),
 613                std::__iterator_category(__out));
 614     }
 615
 616   // Public interface.
 617   template<typename _IIter1, typename _IIter2,
 618            typename _OutputIterator, typename _Predicate>
 619     inline _OutputIterator
 620     set_symmetric_difference(_IIter1 __begin1, _IIter1 __end1,
 621                              _IIter2 __begin2, _IIter2 __end2,
 622                              _OutputIterator __out, _Predicate __pred)
 623     {
 624       return __set_symmetric_difference_switch(
 625                __begin1, __end1, __begin2, __end2, __out, __pred,
 626                std::__iterator_category(__begin1),
 627                std::__iterator_category(__begin2),
 628                std::__iterator_category(__out));
 629     }
 630
 631   // Sequential fallback.
 632   template<typename _IIter1, typename _IIter2,
 633            typename _OutputIterator>
 634     inline _OutputIterator
 635     set_difference(_IIter1 __begin1, _IIter1 __end1,
 636                    _IIter2 __begin2, _IIter2 __end2,
 637                    _OutputIterator __out, __gnu_parallel::sequential_tag)
 638     { return _GLIBCXX_STD_A::set_difference(
 639                __begin1,__end1, __begin2, __end2, __out); }
 640
 641   // Sequential fallback.
 642   template<typename _IIter1, typename _IIter2,
 643            typename _OutputIterator, typename _Predicate>
 644     inline _OutputIterator
 645     set_difference(_IIter1 __begin1, _IIter1 __end1,
 646                    _IIter2 __begin2, _IIter2 __end2,
 647                    _OutputIterator __out, _Predicate __pred,
 648                    __gnu_parallel::sequential_tag)
 649     { return _GLIBCXX_STD_A::set_difference(__begin1, __end1,
 650                                             __begin2, __end2, __out, __pred); }
 651
 652   // Sequential fallback for input iterator case.
 653   template<typename _IIter1, typename _IIter2, typename _Predicate,
 654            typename _OutputIterator, typename _IteratorTag1,
 655            typename _IteratorTag2, typename _IteratorTag3>
 656     inline _OutputIterator
 657     __set_difference_switch(_IIter1 __begin1, _IIter1 __end1,
 658                             _IIter2 __begin2, _IIter2 __end2,
 659                             _OutputIterator __result, _Predicate __pred,
 660                             _IteratorTag1, _IteratorTag2, _IteratorTag3)
 661     { return _GLIBCXX_STD_A::set_difference(
 662                __begin1, __end1, __begin2, __end2, __result, __pred); }
 663
 664   // Parallel set_difference for random access iterators
 665   template<typename _RAIter1, typename _RAIter2,
 666            typename _Output_RAIter, typename _Predicate>
 667     _Output_RAIter
 668     __set_difference_switch(_RAIter1 __begin1,
 669                             _RAIter1 __end1,
 670                             _RAIter2 __begin2,
 671                             _RAIter2 __end2,
 672                             _Output_RAIter __result, _Predicate __pred,
 673                             random_access_iterator_tag,
 674                             random_access_iterator_tag,
 675                             random_access_iterator_tag)
 676     {
 677       if (_GLIBCXX_PARALLEL_CONDITION(
 678             static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
 679             >= __gnu_parallel::_Settings::get().set_difference_minimal_n
 680             || static_cast<__gnu_parallel::_SequenceIndex>(__end2 - __begin2)
 681             >= __gnu_parallel::_Settings::get().set_difference_minimal_n))
 682         return __gnu_parallel::__parallel_set_difference(
 683                  __begin1, __end1, __begin2, __end2, __result, __pred);
 684       else
 685         return _GLIBCXX_STD_A::set_difference(
 686                  __begin1, __end1, __begin2, __end2, __result, __pred);
 687     }
 688
 689   // Public interface
 690   template<typename _IIter1, typename _IIter2,
 691            typename _OutputIterator>
 692     inline _OutputIterator
 693     set_difference(_IIter1 __begin1, _IIter1 __end1,
 694                    _IIter2 __begin2, _IIter2 __end2,
 695                    _OutputIterator __out)
 696     {
 697       typedef typename std::iterator_traits<_IIter1>::value_type _ValueType1;
 698       typedef typename std::iterator_traits<_IIter2>::value_type _ValueType2;
 699
 700       return __set_difference_switch(
 701                __begin1, __end1, __begin2, __end2, __out,
 702                __gnu_parallel::_Less<_ValueType1, _ValueType2>(),
 703                std::__iterator_category(__begin1),
 704                std::__iterator_category(__begin2),
 705                std::__iterator_category(__out));
 706     }
 707
 708   // Public interface
 709   template<typename _IIter1, typename _IIter2,
 710            typename _OutputIterator, typename _Predicate>
 711     inline _OutputIterator
 712     set_difference(_IIter1 __begin1, _IIter1 __end1,
 713                    _IIter2 __begin2, _IIter2 __end2,
 714                    _OutputIterator __out, _Predicate __pred)
 715     {
 716       return __set_difference_switch(
 717                __begin1, __end1, __begin2, __end2, __out, __pred,
 718                std::__iterator_category(__begin1),
 719                std::__iterator_category(__begin2),
 720                std::__iterator_category(__out));
 721     }
 722
 723   // Sequential fallback
 724   template<typename _FIterator>
 725     inline _FIterator
 726     adjacent_find(_FIterator __begin, _FIterator __end,
 727                   __gnu_parallel::sequential_tag)
 728     { return _GLIBCXX_STD_A::adjacent_find(__begin, __end); }
 729
 730   // Sequential fallback
 731   template<typename _FIterator, typename _BinaryPredicate>
 732     inline _FIterator
 733     adjacent_find(_FIterator __begin, _FIterator __end,
 734                   _BinaryPredicate __binary_pred,
 735                   __gnu_parallel::sequential_tag)
 736     { return _GLIBCXX_STD_A::adjacent_find(__begin, __end, __binary_pred); }
 737
 738   // Parallel algorithm for random access iterators
 739   template<typename _RAIter>
 740     _RAIter
 741     __adjacent_find_switch(_RAIter __begin, _RAIter __end,
 742                            random_access_iterator_tag)
 743     {
 744       typedef iterator_traits<_RAIter> _TraitsType;
 745       typedef typename _TraitsType::value_type _ValueType;
 746
 747       if (_GLIBCXX_PARALLEL_CONDITION(true))
 748         {
 749           _RAIter __spot = __gnu_parallel::
 750               __find_template(
 751                 __begin, __end - 1, __begin, equal_to<_ValueType>(),
 752                 __gnu_parallel::__adjacent_find_selector())
 753             .first;
 754           if (__spot == (__end - 1))
 755             return __end;
 756           else
 757             return __spot;
 758         }
 759       else
 760         return adjacent_find(__begin, __end, __gnu_parallel::sequential_tag());
 761     }
 762
 763   // Sequential fallback for input iterator case
 764   template<typename _FIterator, typename _IteratorTag>
 765     inline _FIterator
 766     __adjacent_find_switch(_FIterator __begin, _FIterator __end,
 767                            _IteratorTag)
 768     { return adjacent_find(__begin, __end, __gnu_parallel::sequential_tag()); }
 769
 770   // Public interface
 771   template<typename _FIterator>
 772     inline _FIterator
 773     adjacent_find(_FIterator __begin, _FIterator __end)
 774     {
 775       return __adjacent_find_switch(__begin, __end,
 776                                     std::__iterator_category(__begin));
 777     }
 778
 779   // Sequential fallback for input iterator case
 780   template<typename _FIterator, typename _BinaryPredicate,
 781            typename _IteratorTag>
 782     inline _FIterator
 783     __adjacent_find_switch(_FIterator __begin, _FIterator __end,
 784                            _BinaryPredicate __pred, _IteratorTag)
 785     { return adjacent_find(__begin, __end, __pred,
 786                            __gnu_parallel::sequential_tag()); }
 787
 788   // Parallel algorithm for random access iterators
 789   template<typename _RAIter, typename _BinaryPredicate>
 790     _RAIter
 791     __adjacent_find_switch(_RAIter __begin, _RAIter __end,
 792                            _BinaryPredicate __pred, random_access_iterator_tag)
 793     {
 794       if (_GLIBCXX_PARALLEL_CONDITION(true))
 795         return __gnu_parallel::__find_template(__begin, __end, __begin, __pred,
 796                                              __gnu_parallel::
 797                                              __adjacent_find_selector()).first;
 798       else
 799         return adjacent_find(__begin, __end, __pred,
 800                              __gnu_parallel::sequential_tag());
 801     }
 802
 803   // Public interface
 804   template<typename _FIterator, typename _BinaryPredicate>
 805     inline _FIterator
 806     adjacent_find(_FIterator __begin, _FIterator __end,
 807                   _BinaryPredicate __pred)
 808     {
 809       return __adjacent_find_switch(__begin, __end, __pred,
 810                                     std::__iterator_category(__begin));
 811     }
 812
 813   // Sequential fallback
 814   template<typename _IIter, typename _Tp>
 815     inline typename iterator_traits<_IIter>::difference_type
 816     count(_IIter __begin, _IIter __end, const _Tp& __value,
 817           __gnu_parallel::sequential_tag)
 818     { return _GLIBCXX_STD_A::count(__begin, __end, __value); }
 819
 820   // Parallel code for random access iterators
 821   template<typename _RAIter, typename _Tp>
 822     typename iterator_traits<_RAIter>::difference_type
 823     __count_switch(_RAIter __begin, _RAIter __end,
 824                    const _Tp& __value, random_access_iterator_tag,
 825                    __gnu_parallel::_Parallelism __parallelism_tag)
 826     {
 827       typedef iterator_traits<_RAIter> _TraitsType;
 828       typedef typename _TraitsType::value_type _ValueType;
 829       typedef typename _TraitsType::difference_type _DifferenceType;
 830       typedef __gnu_parallel::_SequenceIndex _SequenceIndex;
 831
 832       if (_GLIBCXX_PARALLEL_CONDITION(
 833             static_cast<_SequenceIndex>(__end - __begin)
 834             >= __gnu_parallel::_Settings::get().count_minimal_n
 835             && __gnu_parallel::__is_parallel(__parallelism_tag)))
 836         {
 837           __gnu_parallel::__count_selector<_RAIter, _DifferenceType>
 838             __functionality;
 839           _DifferenceType __res = 0;
 840           __gnu_parallel::
 841             __for_each_template_random_access(
 842               __begin, __end, __value, __functionality,
 843               std::plus<_SequenceIndex>(), __res, __res, -1,
 844               __parallelism_tag);
 845           return __res;
 846         }
 847       else
 848         return count(__begin, __end, __value,
 849                      __gnu_parallel::sequential_tag());
 850     }
 851
 852   // Sequential fallback for input iterator case.
 853   template<typename _IIter, typename _Tp, typename _IteratorTag>
 854     inline typename iterator_traits<_IIter>::difference_type
 855     __count_switch(_IIter __begin, _IIter __end, const _Tp& __value,
 856                    _IteratorTag)
 857     { return count(__begin, __end, __value, __gnu_parallel::sequential_tag());
 858       }
 859
 860   // Public interface.
 861   template<typename _IIter, typename _Tp>
 862     inline typename iterator_traits<_IIter>::difference_type
 863     count(_IIter __begin, _IIter __end, const _Tp& __value,
 864           __gnu_parallel::_Parallelism __parallelism_tag)
 865     {
 866       return __count_switch(__begin, __end, __value,
 867                             std::__iterator_category(__begin),
 868                             __parallelism_tag);
 869     }
 870
 871   template<typename _IIter, typename _Tp>
 872     inline typename iterator_traits<_IIter>::difference_type
 873     count(_IIter __begin, _IIter __end, const _Tp& __value)
 874     {
 875       return __count_switch(__begin, __end, __value,
 876                             std::__iterator_category(__begin));
 877     }
 878
 879
 880   // Sequential fallback.
 881   template<typename _IIter, typename _Predicate>
 882     inline typename iterator_traits<_IIter>::difference_type
 883     count_if(_IIter __begin, _IIter __end, _Predicate __pred,
 884              __gnu_parallel::sequential_tag)
 885     { return _GLIBCXX_STD_A::count_if(__begin, __end, __pred); }
 886
 887   // Parallel count_if for random access iterators
 888   template<typename _RAIter, typename _Predicate>
 889     typename iterator_traits<_RAIter>::difference_type
 890     __count_if_switch(_RAIter __begin, _RAIter __end,
 891                       _Predicate __pred, random_access_iterator_tag,
 892                       __gnu_parallel::_Parallelism __parallelism_tag)
 893     {
 894       typedef iterator_traits<_RAIter> _TraitsType;
 895       typedef typename _TraitsType::value_type _ValueType;
 896       typedef typename _TraitsType::difference_type _DifferenceType;
 897       typedef __gnu_parallel::_SequenceIndex _SequenceIndex;
 898
 899       if (_GLIBCXX_PARALLEL_CONDITION(
 900             static_cast<_SequenceIndex>(__end - __begin)
 901             >= __gnu_parallel::_Settings::get().count_minimal_n
 902             && __gnu_parallel::__is_parallel(__parallelism_tag)))
 903         {
 904           _DifferenceType __res = 0;
 905           __gnu_parallel::
 906             __count_if_selector<_RAIter, _DifferenceType>
 907             __functionality;
 908           __gnu_parallel::
 909             __for_each_template_random_access(
 910               __begin, __end, __pred, __functionality,
 911               std::plus<_SequenceIndex>(), __res, __res, -1,
 912               __parallelism_tag);
 913           return __res;
 914         }
 915       else
 916         return count_if(__begin, __end, __pred,
 917                         __gnu_parallel::sequential_tag());
 918     }
 919
 920   // Sequential fallback for input iterator case.
 921   template<typename _IIter, typename _Predicate, typename _IteratorTag>
 922     inline typename iterator_traits<_IIter>::difference_type
 923     __count_if_switch(_IIter __begin, _IIter __end, _Predicate __pred,
 924                       _IteratorTag)
 925     { return count_if(__begin, __end, __pred,
 926                       __gnu_parallel::sequential_tag()); }
 927
 928   // Public interface.
 929   template<typename _IIter, typename _Predicate>
 930     inline typename iterator_traits<_IIter>::difference_type
 931     count_if(_IIter __begin, _IIter __end, _Predicate __pred,
 932              __gnu_parallel::_Parallelism __parallelism_tag)
 933     {
 934       return __count_if_switch(__begin, __end, __pred,
 935                                std::__iterator_category(__begin),
 936                                __parallelism_tag);
 937     }
 938
 939   template<typename _IIter, typename _Predicate>
 940     inline typename iterator_traits<_IIter>::difference_type
 941     count_if(_IIter __begin, _IIter __end, _Predicate __pred)
 942     {
 943       return __count_if_switch(__begin, __end, __pred,
 944                                std::__iterator_category(__begin));
 945     }
 946
 947
 948   // Sequential fallback.
 949   template<typename _FIterator1, typename _FIterator2>
 950     inline _FIterator1
 951     search(_FIterator1 __begin1, _FIterator1 __end1,
 952            _FIterator2 __begin2, _FIterator2 __end2,
 953            __gnu_parallel::sequential_tag)
 954     { return _GLIBCXX_STD_A::search(__begin1, __end1, __begin2, __end2); }
 955
 956   // Parallel algorithm for random access iterator
 957   template<typename _RAIter1, typename _RAIter2>
 958     _RAIter1
 959     __search_switch(_RAIter1 __begin1, _RAIter1 __end1,
 960                     _RAIter2 __begin2, _RAIter2 __end2,
 961                     random_access_iterator_tag, random_access_iterator_tag)
 962     {
 963       typedef typename std::iterator_traits<_RAIter1>::value_type _ValueType1;
 964       typedef typename std::iterator_traits<_RAIter2>::value_type _ValueType2;
 965
 966       if (_GLIBCXX_PARALLEL_CONDITION(
 967                 static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
 968             >= __gnu_parallel::_Settings::get().search_minimal_n))
 969         return __gnu_parallel::
 970           __search_template(
 971             __begin1, __end1, __begin2, __end2,
 972             __gnu_parallel::_EqualTo<_ValueType1, _ValueType2>());
 973       else
 974         return search(__begin1, __end1, __begin2, __end2,
 975                       __gnu_parallel::sequential_tag());
 976     }
 977
 978   // Sequential fallback for input iterator case
 979   template<typename _FIterator1, typename _FIterator2,
 980            typename _IteratorTag1, typename _IteratorTag2>
 981     inline _FIterator1
 982     __search_switch(_FIterator1 __begin1, _FIterator1 __end1,
 983                     _FIterator2 __begin2, _FIterator2 __end2,
 984                     _IteratorTag1, _IteratorTag2)
 985     { return search(__begin1, __end1, __begin2, __end2,
 986                     __gnu_parallel::sequential_tag()); }
 987
 988   // Public interface.
 989   template<typename _FIterator1, typename _FIterator2>
 990     inline _FIterator1
 991     search(_FIterator1 __begin1, _FIterator1 __end1,
 992            _FIterator2 __begin2, _FIterator2 __end2)
 993     {
 994       return __search_switch(__begin1, __end1, __begin2, __end2,
 995                              std::__iterator_category(__begin1),
 996                              std::__iterator_category(__begin2));
 997     }
 998
 999 #if __cplusplus >= 201703L
1000   /** @brief Search a sequence using a Searcher object.
1001    *
1002    *  @param  __first        A forward iterator.
1003    *  @param  __last         A forward iterator.
1004    *  @param  __searcher     A callable object.
1005    *  @return @p __searcher(__first,__last).first
1006   */
1007   template<typename _ForwardIterator, typename _Searcher>
1008     inline _ForwardIterator
1009     search(_ForwardIterator __first, _ForwardIterator __last,
1010            const _Searcher& __searcher)
1011     { return __searcher(__first, __last).first; }
1012 #endif
1013
1014   // Sequential fallback
1015   template<typename _FIterator, typename _Integer, typename _Tp>
1016     inline _FIterator
1017     search_n(_FIterator __begin, _FIterator __end, _Integer __count,
1018              const _Tp& __val, __gnu_parallel::sequential_tag)
1019     { return _GLIBCXX_STD_A::search_n(__begin, __end, __count, __val); }
1020
1021   // Sequential fallback
1022   template<typename _FIterator, typename _Integer, typename _Tp,
1023            typename _BinaryPredicate>
1024     inline _FIterator
1025     search_n(_FIterator __begin, _FIterator __end, _Integer __count,
1026              const _Tp& __val, _BinaryPredicate __binary_pred,
1027              __gnu_parallel::sequential_tag)
1028     { return _GLIBCXX_STD_A::search_n(
1029                __begin, __end, __count, __val, __binary_pred); }
1030
1031   // Public interface.
1032   template<typename _FIterator, typename _Integer, typename _Tp>
1033     inline _FIterator
1034     search_n(_FIterator __begin, _FIterator __end, _Integer __count,
1035              const _Tp& __val)
1036     {
1037       typedef typename iterator_traits<_FIterator>::value_type _ValueType;
1038       return __gnu_parallel::search_n(__begin, __end, __count, __val,
1039                       __gnu_parallel::_EqualTo<_ValueType, _Tp>());
1040     }
1041
1042   // Parallel algorithm for random access iterators.
1043   template<typename _RAIter, typename _Integer,
1044            typename _Tp, typename _BinaryPredicate>
1045     _RAIter
1046     __search_n_switch(_RAIter __begin, _RAIter __end, _Integer __count,
1047                       const _Tp& __val, _BinaryPredicate __binary_pred,
1048                       random_access_iterator_tag)
1049     {
1050       if (_GLIBCXX_PARALLEL_CONDITION(
1051                 static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1052             >= __gnu_parallel::_Settings::get().search_minimal_n))
1053         {
1054           __gnu_parallel::_PseudoSequence<_Tp, _Integer> __ps(__val, __count);
1055           return __gnu_parallel::__search_template(
1056                    __begin, __end, __ps.begin(), __ps.end(), __binary_pred);
1057         }
1058       else
1059         return _GLIBCXX_STD_A::search_n(__begin, __end, __count, __val,
1060                                         __binary_pred);
1061     }
1062
1063   // Sequential fallback for input iterator case.
1064   template<typename _FIterator, typename _Integer, typename _Tp,
1065            typename _BinaryPredicate, typename _IteratorTag>
1066     inline _FIterator
1067     __search_n_switch(_FIterator __begin, _FIterator __end, _Integer __count,
1068                       const _Tp& __val, _BinaryPredicate __binary_pred,
1069                       _IteratorTag)
1070     { return _GLIBCXX_STD_A::search_n(__begin, __end, __count, __val,
1071                                       __binary_pred); }
1072
1073   // Public interface.
1074   template<typename _FIterator, typename _Integer, typename _Tp,
1075            typename _BinaryPredicate>
1076     inline _FIterator
1077     search_n(_FIterator __begin, _FIterator __end, _Integer __count,
1078              const _Tp& __val, _BinaryPredicate __binary_pred)
1079     {
1080       return __search_n_switch(__begin, __end, __count, __val, __binary_pred,
1081                                std::__iterator_category(__begin));
1082     }
1083
1084
1085   // Sequential fallback.
1086   template<typename _IIter, typename _OutputIterator,
1087            typename _UnaryOperation>
1088     inline _OutputIterator
1089     transform(_IIter __begin, _IIter __end, _OutputIterator __result,
1090               _UnaryOperation __unary_op, __gnu_parallel::sequential_tag)
1091     { return _GLIBCXX_STD_A::transform(__begin, __end, __result, __unary_op); }
1092
1093   // Parallel unary transform for random access iterators.
1094   template<typename _RAIter1, typename _RAIter2,
1095            typename _UnaryOperation>
1096     _RAIter2
1097     __transform1_switch(_RAIter1 __begin, _RAIter1 __end,
1098                         _RAIter2 __result, _UnaryOperation __unary_op,
1099                         random_access_iterator_tag, random_access_iterator_tag,
1100                         __gnu_parallel::_Parallelism __parallelism_tag)
1101     {
1102       if (_GLIBCXX_PARALLEL_CONDITION(
1103             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1104             >= __gnu_parallel::_Settings::get().transform_minimal_n
1105             && __gnu_parallel::__is_parallel(__parallelism_tag)))
1106         {
1107           bool __dummy = true;
1108           typedef __gnu_parallel::_IteratorPair<_RAIter1,
1109             _RAIter2, random_access_iterator_tag> _ItTrip;
1110           _ItTrip __begin_pair(__begin, __result),
1111                   __end_pair(__end, __result + (__end - __begin));
1112           __gnu_parallel::__transform1_selector<_ItTrip> __functionality;
1113           __gnu_parallel::
1114             __for_each_template_random_access(
1115               __begin_pair, __end_pair, __unary_op, __functionality,
1116               __gnu_parallel::_DummyReduct(),
1117               __dummy, __dummy, -1, __parallelism_tag);
1118           return __functionality._M_finish_iterator;
1119         }
1120       else
1121         return transform(__begin, __end, __result, __unary_op,
1122                          __gnu_parallel::sequential_tag());
1123     }
1124
1125   // Sequential fallback for input iterator case.
1126   template<typename _RAIter1, typename _RAIter2,
1127            typename _UnaryOperation, typename _IteratorTag1,
1128            typename _IteratorTag2>
1129     inline _RAIter2
1130     __transform1_switch(_RAIter1 __begin, _RAIter1 __end,
1131                         _RAIter2 __result, _UnaryOperation __unary_op,
1132                         _IteratorTag1, _IteratorTag2)
1133     { return transform(__begin, __end, __result, __unary_op,
1134                        __gnu_parallel::sequential_tag()); }
1135
1136   // Public interface.
1137   template<typename _IIter, typename _OutputIterator,
1138            typename _UnaryOperation>
1139     inline _OutputIterator
1140     transform(_IIter __begin, _IIter __end, _OutputIterator __result,
1141               _UnaryOperation __unary_op,
1142               __gnu_parallel::_Parallelism __parallelism_tag)
1143     {
1144       return __transform1_switch(__begin, __end, __result, __unary_op,
1145                                  std::__iterator_category(__begin),
1146                                  std::__iterator_category(__result),
1147                                  __parallelism_tag);
1148     }
1149
1150   template<typename _IIter, typename _OutputIterator,
1151            typename _UnaryOperation>
1152     inline _OutputIterator
1153     transform(_IIter __begin, _IIter __end, _OutputIterator __result,
1154               _UnaryOperation __unary_op)
1155     {
1156       return __transform1_switch(__begin, __end, __result, __unary_op,
1157                                  std::__iterator_category(__begin),
1158                                  std::__iterator_category(__result));
1159     }
1160
1161
1162   // Sequential fallback
1163   template<typename _IIter1, typename _IIter2,
1164            typename _OutputIterator, typename _BinaryOperation>
1165     inline _OutputIterator
1166     transform(_IIter1 __begin1, _IIter1 __end1,
1167               _IIter2 __begin2, _OutputIterator __result,
1168               _BinaryOperation __binary_op, __gnu_parallel::sequential_tag)
1169     { return _GLIBCXX_STD_A::transform(__begin1, __end1,
1170                                        __begin2, __result, __binary_op); }
1171
1172   // Parallel binary transform for random access iterators.
1173   template<typename _RAIter1, typename _RAIter2,
1174            typename _RAIter3, typename _BinaryOperation>
1175     _RAIter3
1176     __transform2_switch(_RAIter1 __begin1, _RAIter1 __end1,
1177                         _RAIter2 __begin2,
1178                         _RAIter3 __result, _BinaryOperation __binary_op,
1179                         random_access_iterator_tag, random_access_iterator_tag,
1180                         random_access_iterator_tag,
1181                         __gnu_parallel::_Parallelism __parallelism_tag)
1182     {
1183       if (_GLIBCXX_PARALLEL_CONDITION(
1184             (__end1 - __begin1) >=
1185                 __gnu_parallel::_Settings::get().transform_minimal_n
1186             && __gnu_parallel::__is_parallel(__parallelism_tag)))
1187         {
1188           bool __dummy = true;
1189           typedef __gnu_parallel::_IteratorTriple<_RAIter1,
1190             _RAIter2, _RAIter3,
1191             random_access_iterator_tag> _ItTrip;
1192           _ItTrip __begin_triple(__begin1, __begin2, __result),
1193             __end_triple(__end1, __begin2 + (__end1 - __begin1),
1194                        __result + (__end1 - __begin1));
1195           __gnu_parallel::__transform2_selector<_ItTrip> __functionality;
1196           __gnu_parallel::
1197             __for_each_template_random_access(__begin_triple, __end_triple,
1198                                               __binary_op, __functionality,
1199                                               __gnu_parallel::_DummyReduct(),
1200                                               __dummy, __dummy, -1,
1201                                               __parallelism_tag);
1202           return __functionality._M_finish_iterator;
1203         }
1204       else
1205         return transform(__begin1, __end1, __begin2, __result, __binary_op,
1206                          __gnu_parallel::sequential_tag());
1207     }
1208
1209   // Sequential fallback for input iterator case.
1210   template<typename _IIter1, typename _IIter2,
1211            typename _OutputIterator, typename _BinaryOperation,
1212            typename _Tag1, typename _Tag2, typename _Tag3>
1213     inline _OutputIterator
1214     __transform2_switch(_IIter1 __begin1, _IIter1 __end1,
1215                         _IIter2 __begin2, _OutputIterator __result,
1216                         _BinaryOperation __binary_op, _Tag1, _Tag2, _Tag3)
1217     { return transform(__begin1, __end1, __begin2, __result, __binary_op,
1218                        __gnu_parallel::sequential_tag()); }
1219
1220   // Public interface.
1221   template<typename _IIter1, typename _IIter2,
1222            typename _OutputIterator, typename _BinaryOperation>
1223     inline _OutputIterator
1224     transform(_IIter1 __begin1, _IIter1 __end1,
1225               _IIter2 __begin2, _OutputIterator __result,
1226               _BinaryOperation __binary_op,
1227               __gnu_parallel::_Parallelism __parallelism_tag)
1228     {
1229       return __transform2_switch(
1230                __begin1, __end1, __begin2, __result, __binary_op,
1231                std::__iterator_category(__begin1),
1232                std::__iterator_category(__begin2),
1233                std::__iterator_category(__result),
1234                __parallelism_tag);
1235     }
1236
1237   template<typename _IIter1, typename _IIter2,
1238            typename _OutputIterator, typename _BinaryOperation>
1239     inline _OutputIterator
1240     transform(_IIter1 __begin1, _IIter1 __end1,
1241               _IIter2 __begin2, _OutputIterator __result,
1242               _BinaryOperation __binary_op)
1243     {
1244       return __transform2_switch(
1245                __begin1, __end1, __begin2, __result, __binary_op,
1246                std::__iterator_category(__begin1),
1247                std::__iterator_category(__begin2),
1248                std::__iterator_category(__result));
1249     }
1250
1251   // Sequential fallback
1252   template<typename _FIterator, typename _Tp>
1253     inline void
1254     replace(_FIterator __begin, _FIterator __end, const _Tp& __old_value,
1255             const _Tp& __new_value, __gnu_parallel::sequential_tag)
1256     { _GLIBCXX_STD_A::replace(__begin, __end, __old_value, __new_value); }
1257
1258   // Sequential fallback for input iterator case
1259   template<typename _FIterator, typename _Tp, typename _IteratorTag>
1260     inline void
1261     __replace_switch(_FIterator __begin, _FIterator __end,
1262                      const _Tp& __old_value, const _Tp& __new_value,
1263                      _IteratorTag)
1264     { replace(__begin, __end, __old_value, __new_value,
1265               __gnu_parallel::sequential_tag()); }
1266
1267   // Parallel replace for random access iterators
1268   template<typename _RAIter, typename _Tp>
1269     inline void
1270     __replace_switch(_RAIter __begin, _RAIter __end,
1271                      const _Tp& __old_value, const _Tp& __new_value,
1272                      random_access_iterator_tag,
1273                      __gnu_parallel::_Parallelism __parallelism_tag)
1274     {
1275       // XXX parallel version is where?
1276       replace(__begin, __end, __old_value, __new_value,
1277               __gnu_parallel::sequential_tag());
1278     }
1279
1280   // Public interface
1281   template<typename _FIterator, typename _Tp>
1282     inline void
1283     replace(_FIterator __begin, _FIterator __end, const _Tp& __old_value,
1284             const _Tp& __new_value,
1285             __gnu_parallel::_Parallelism __parallelism_tag)
1286     {
1287       __replace_switch(__begin, __end, __old_value, __new_value,
1288                        std::__iterator_category(__begin),
1289                        __parallelism_tag);
1290     }
1291
1292   template<typename _FIterator, typename _Tp>
1293     inline void
1294     replace(_FIterator __begin, _FIterator __end, const _Tp& __old_value,
1295             const _Tp& __new_value)
1296     {
1297       __replace_switch(__begin, __end, __old_value, __new_value,
1298                        std::__iterator_category(__begin));
1299     }
1300
1301
1302   // Sequential fallback
1303   template<typename _FIterator, typename _Predicate, typename _Tp>
1304     inline void
1305     replace_if(_FIterator __begin, _FIterator __end, _Predicate __pred,
1306                const _Tp& __new_value, __gnu_parallel::sequential_tag)
1307     { _GLIBCXX_STD_A::replace_if(__begin, __end, __pred, __new_value); }
1308
1309   // Sequential fallback for input iterator case
1310   template<typename _FIterator, typename _Predicate, typename _Tp,
1311            typename _IteratorTag>
1312     inline void
1313     __replace_if_switch(_FIterator __begin, _FIterator __end,
1314                         _Predicate __pred, const _Tp& __new_value, _IteratorTag)
1315     { replace_if(__begin, __end, __pred, __new_value,
1316                  __gnu_parallel::sequential_tag()); }
1317
1318   // Parallel algorithm for random access iterators.
1319   template<typename _RAIter, typename _Predicate, typename _Tp>
1320     void
1321     __replace_if_switch(_RAIter __begin, _RAIter __end,
1322                         _Predicate __pred, const _Tp& __new_value,
1323                         random_access_iterator_tag,
1324                         __gnu_parallel::_Parallelism __parallelism_tag)
1325     {
1326       if (_GLIBCXX_PARALLEL_CONDITION(
1327             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1328             >= __gnu_parallel::_Settings::get().replace_minimal_n
1329             && __gnu_parallel::__is_parallel(__parallelism_tag)))
1330         {
1331           bool __dummy;
1332           __gnu_parallel::
1333             __replace_if_selector<_RAIter, _Predicate, _Tp>
1334             __functionality(__new_value);
1335           __gnu_parallel::
1336             __for_each_template_random_access(
1337               __begin, __end, __pred, __functionality,
1338               __gnu_parallel::_DummyReduct(),
1339               true, __dummy, -1, __parallelism_tag);
1340         }
1341       else
1342         replace_if(__begin, __end, __pred, __new_value,
1343                    __gnu_parallel::sequential_tag());
1344     }
1345
1346   // Public interface.
1347   template<typename _FIterator, typename _Predicate, typename _Tp>
1348     inline void
1349     replace_if(_FIterator __begin, _FIterator __end,
1350                _Predicate __pred, const _Tp& __new_value,
1351                __gnu_parallel::_Parallelism __parallelism_tag)
1352     {
1353       __replace_if_switch(__begin, __end, __pred, __new_value,
1354                           std::__iterator_category(__begin),
1355                           __parallelism_tag);
1356     }
1357
1358   template<typename _FIterator, typename _Predicate, typename _Tp>
1359     inline void
1360     replace_if(_FIterator __begin, _FIterator __end,
1361                _Predicate __pred, const _Tp& __new_value)
1362     {
1363       __replace_if_switch(__begin, __end, __pred, __new_value,
1364                           std::__iterator_category(__begin));
1365     }
1366
1367   // Sequential fallback
1368   template<typename _FIterator, typename _Generator>
1369     inline void
1370     generate(_FIterator __begin, _FIterator __end, _Generator __gen,
1371              __gnu_parallel::sequential_tag)
1372     { _GLIBCXX_STD_A::generate(__begin, __end, __gen); }
1373
1374   // Sequential fallback for input iterator case.
1375   template<typename _FIterator, typename _Generator, typename _IteratorTag>
1376     inline void
1377     __generate_switch(_FIterator __begin, _FIterator __end, _Generator __gen,
1378                       _IteratorTag)
1379     { generate(__begin, __end, __gen, __gnu_parallel::sequential_tag()); }
1380
1381   // Parallel algorithm for random access iterators.
1382   template<typename _RAIter, typename _Generator>
1383     void
1384     __generate_switch(_RAIter __begin, _RAIter __end,
1385                       _Generator __gen, random_access_iterator_tag,
1386                       __gnu_parallel::_Parallelism __parallelism_tag)
1387     {
1388       if (_GLIBCXX_PARALLEL_CONDITION(
1389             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1390             >= __gnu_parallel::_Settings::get().generate_minimal_n
1391             && __gnu_parallel::__is_parallel(__parallelism_tag)))
1392         {
1393           bool __dummy;
1394           __gnu_parallel::__generate_selector<_RAIter>
1395             __functionality;
1396           __gnu_parallel::
1397             __for_each_template_random_access(
1398               __begin, __end, __gen, __functionality,
1399               __gnu_parallel::_DummyReduct(),
1400               true, __dummy, -1, __parallelism_tag);
1401         }
1402       else
1403         generate(__begin, __end, __gen, __gnu_parallel::sequential_tag());
1404     }
1405
1406   // Public interface.
1407   template<typename _FIterator, typename _Generator>
1408     inline void
1409     generate(_FIterator __begin, _FIterator __end,
1410              _Generator __gen, __gnu_parallel::_Parallelism __parallelism_tag)
1411     {
1412       __generate_switch(__begin, __end, __gen,
1413                         std::__iterator_category(__begin),
1414                         __parallelism_tag);
1415     }
1416
1417   template<typename _FIterator, typename _Generator>
1418     inline void
1419     generate(_FIterator __begin, _FIterator __end, _Generator __gen)
1420     {
1421       __generate_switch(__begin, __end, __gen,
1422                         std::__iterator_category(__begin));
1423     }
1424
1425
1426   // Sequential fallback.
1427   template<typename _OutputIterator, typename _Size, typename _Generator>
1428     inline _OutputIterator
1429     generate_n(_OutputIterator __begin, _Size __n, _Generator __gen,
1430                __gnu_parallel::sequential_tag)
1431     { return _GLIBCXX_STD_A::generate_n(__begin, __n, __gen); }
1432
1433   // Sequential fallback for input iterator case.
1434   template<typename _OutputIterator, typename _Size, typename _Generator,
1435            typename _IteratorTag>
1436     inline _OutputIterator
1437     __generate_n_switch(_OutputIterator __begin, _Size __n, _Generator __gen,
1438                         _IteratorTag)
1439     { return generate_n(__begin, __n, __gen,
1440                         __gnu_parallel::sequential_tag()); }
1441
1442   // Parallel algorithm for random access iterators.
1443   template<typename _RAIter, typename _Size, typename _Generator>
1444     inline _RAIter
1445     __generate_n_switch(_RAIter __begin, _Size __n, _Generator __gen,
1446                         random_access_iterator_tag,
1447                         __gnu_parallel::_Parallelism __parallelism_tag)
1448     {
1449       // XXX parallel version is where?
1450       return generate_n(__begin, __n, __gen, __gnu_parallel::sequential_tag());
1451     }
1452
1453   // Public interface.
1454   template<typename _OutputIterator, typename _Size, typename _Generator>
1455     inline _OutputIterator
1456     generate_n(_OutputIterator __begin, _Size __n, _Generator __gen,
1457                __gnu_parallel::_Parallelism __parallelism_tag)
1458     {
1459       return __generate_n_switch(__begin, __n, __gen,
1460                                  std::__iterator_category(__begin),
1461                                  __parallelism_tag);
1462     }
1463
1464   template<typename _OutputIterator, typename _Size, typename _Generator>
1465     inline _OutputIterator
1466     generate_n(_OutputIterator __begin, _Size __n, _Generator __gen)
1467     {
1468       return __generate_n_switch(__begin, __n, __gen,
1469                                  std::__iterator_category(__begin));
1470     }
1471
1472
1473   // Sequential fallback.
1474   template<typename _RAIter>
1475     inline void
1476     random_shuffle(_RAIter __begin, _RAIter __end,
1477                    __gnu_parallel::sequential_tag)
1478     { _GLIBCXX_STD_A::random_shuffle(__begin, __end); }
1479
1480   // Sequential fallback.
1481   template<typename _RAIter, typename _RandomNumberGenerator>
1482     inline void
1483     random_shuffle(_RAIter __begin, _RAIter __end,
1484                    _RandomNumberGenerator& __rand,
1485                    __gnu_parallel::sequential_tag)
1486     { _GLIBCXX_STD_A::random_shuffle(__begin, __end, __rand); }
1487
1488
1489   /** @brief Functor wrapper for std::rand(). */
1490   template<typename _MustBeInt = int>
1491     struct _CRandNumber
1492     {
1493       int
1494       operator()(int __limit)
1495       { return rand() % __limit; }
1496     };
1497
1498   // Fill in random number generator.
1499   template<typename _RAIter>
1500     inline void
1501     random_shuffle(_RAIter __begin, _RAIter __end)
1502     {
1503       _CRandNumber<> __r;
1504       // Parallelization still possible.
1505       __gnu_parallel::random_shuffle(__begin, __end, __r);
1506     }
1507
1508   // Parallel algorithm for random access iterators.
1509   template<typename _RAIter, typename _RandomNumberGenerator>
1510     void
1511     random_shuffle(_RAIter __begin, _RAIter __end,
1512 #if __cplusplus >= 201103L
1513                    _RandomNumberGenerator&& __rand)
1514 #else
1515                    _RandomNumberGenerator& __rand)
1516 #endif
1517     {
1518       if (__begin == __end)
1519         return;
1520       if (_GLIBCXX_PARALLEL_CONDITION(
1521             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1522             >= __gnu_parallel::_Settings::get().random_shuffle_minimal_n))
1523         __gnu_parallel::__parallel_random_shuffle(__begin, __end, __rand);
1524       else
1525         __gnu_parallel::__sequential_random_shuffle(__begin, __end, __rand);
1526     }
1527
1528   // Sequential fallback.
1529   template<typename _FIterator, typename _Predicate>
1530     inline _FIterator
1531     partition(_FIterator __begin, _FIterator __end,
1532               _Predicate __pred, __gnu_parallel::sequential_tag)
1533     { return _GLIBCXX_STD_A::partition(__begin, __end, __pred); }
1534
1535   // Sequential fallback for input iterator case.
1536   template<typename _FIterator, typename _Predicate, typename _IteratorTag>
1537     inline _FIterator
1538     __partition_switch(_FIterator __begin, _FIterator __end,
1539                        _Predicate __pred, _IteratorTag)
1540     { return partition(__begin, __end, __pred,
1541                        __gnu_parallel::sequential_tag()); }
1542
1543   // Parallel algorithm for random access iterators.
1544   template<typename _RAIter, typename _Predicate>
1545     _RAIter
1546     __partition_switch(_RAIter __begin, _RAIter __end,
1547                        _Predicate __pred, random_access_iterator_tag)
1548     {
1549       if (_GLIBCXX_PARALLEL_CONDITION(
1550             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1551             >= __gnu_parallel::_Settings::get().partition_minimal_n))
1552         {
1553           typedef typename std::iterator_traits<_RAIter>::
1554             difference_type _DifferenceType;
1555           _DifferenceType __middle = __gnu_parallel::
1556             __parallel_partition(__begin, __end, __pred,
1557                                __gnu_parallel::__get_max_threads());
1558           return __begin + __middle;
1559         }
1560       else
1561         return partition(__begin, __end, __pred,
1562                          __gnu_parallel::sequential_tag());
1563     }
1564
1565   // Public interface.
1566   template<typename _FIterator, typename _Predicate>
1567     inline _FIterator
1568     partition(_FIterator __begin, _FIterator __end, _Predicate __pred)
1569     {
1570       return __partition_switch(__begin, __end, __pred,
1571                                 std::__iterator_category(__begin));
1572     }
1573
1574   // sort interface
1575
1576   // Sequential fallback
1577   template<typename _RAIter>
1578     inline void
1579     sort(_RAIter __begin, _RAIter __end,
1580          __gnu_parallel::sequential_tag)
1581     { _GLIBCXX_STD_A::sort(__begin, __end); }
1582
1583   // Sequential fallback
1584   template<typename _RAIter, typename _Compare>
1585     inline void
1586     sort(_RAIter __begin, _RAIter __end, _Compare __comp,
1587          __gnu_parallel::sequential_tag)
1588     { _GLIBCXX_STD_A::sort<_RAIter, _Compare>(__begin, __end,
1589                                                              __comp); }
1590
1591   // Public interface
1592   template<typename _RAIter, typename _Compare,
1593            typename _Parallelism>
1594     void
1595     sort(_RAIter __begin, _RAIter __end, _Compare __comp,
1596          _Parallelism __parallelism)
1597   {
1598     typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1599
1600     if (__begin != __end)
1601       {
1602         if (_GLIBCXX_PARALLEL_CONDITION(
1603             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin) >=
1604               __gnu_parallel::_Settings::get().sort_minimal_n))
1605           __gnu_parallel::__parallel_sort<false>(
1606                             __begin, __end, __comp, __parallelism);
1607         else
1608           sort(__begin, __end, __comp, __gnu_parallel::sequential_tag());
1609       }
1610   }
1611
1612   // Public interface, insert default comparator
1613   template<typename _RAIter>
1614     inline void
1615     sort(_RAIter __begin, _RAIter __end)
1616     {
1617       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1618       sort(__begin, __end, std::less<_ValueType>(),
1619            __gnu_parallel::default_parallel_tag());
1620     }
1621
1622   // Public interface, insert default comparator
1623   template<typename _RAIter>
1624     inline void
1625     sort(_RAIter __begin, _RAIter __end,
1626          __gnu_parallel::default_parallel_tag __parallelism)
1627     {
1628       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1629       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1630     }
1631
1632   // Public interface, insert default comparator
1633   template<typename _RAIter>
1634     inline void
1635     sort(_RAIter __begin, _RAIter __end,
1636          __gnu_parallel::parallel_tag __parallelism)
1637     {
1638       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1639       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1640     }
1641
1642   // Public interface, insert default comparator
1643   template<typename _RAIter>
1644     inline void
1645     sort(_RAIter __begin, _RAIter __end,
1646          __gnu_parallel::multiway_mergesort_tag __parallelism)
1647     {
1648       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1649       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1650     }
1651
1652   // Public interface, insert default comparator
1653   template<typename _RAIter>
1654     inline void
1655     sort(_RAIter __begin, _RAIter __end,
1656          __gnu_parallel::multiway_mergesort_sampling_tag __parallelism)
1657     {
1658       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1659       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1660     }
1661
1662   // Public interface, insert default comparator
1663   template<typename _RAIter>
1664     inline void
1665     sort(_RAIter __begin, _RAIter __end,
1666          __gnu_parallel::multiway_mergesort_exact_tag __parallelism)
1667     {
1668       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1669       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1670     }
1671
1672   // Public interface, insert default comparator
1673   template<typename _RAIter>
1674     inline void
1675     sort(_RAIter __begin, _RAIter __end,
1676          __gnu_parallel::quicksort_tag __parallelism)
1677     {
1678       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1679       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1680     }
1681
1682   // Public interface, insert default comparator
1683   template<typename _RAIter>
1684     inline void
1685     sort(_RAIter __begin, _RAIter __end,
1686          __gnu_parallel::balanced_quicksort_tag __parallelism)
1687     {
1688       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1689       sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1690     }
1691
1692   // Public interface
1693   template<typename _RAIter, typename _Compare>
1694     void
1695     sort(_RAIter __begin, _RAIter __end, _Compare __comp)
1696     {
1697       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1698       sort(__begin, __end, __comp, __gnu_parallel::default_parallel_tag());
1699     }
1700
1701   // stable_sort interface
1702
1703
1704   // Sequential fallback
1705   template<typename _RAIter>
1706     inline void
1707     stable_sort(_RAIter __begin, _RAIter __end,
1708                 __gnu_parallel::sequential_tag)
1709     { _GLIBCXX_STD_A::stable_sort(__begin, __end); }
1710
1711   // Sequential fallback
1712   template<typename _RAIter, typename _Compare>
1713     inline void
1714     stable_sort(_RAIter __begin, _RAIter __end,
1715                 _Compare __comp, __gnu_parallel::sequential_tag)
1716     { _GLIBCXX_STD_A::stable_sort<_RAIter, _Compare>(__begin, __end, __comp); }
1717
1718   // Public interface
1719   template<typename _RAIter, typename _Compare,
1720            typename _Parallelism>
1721     void
1722     stable_sort(_RAIter __begin, _RAIter __end,
1723                 _Compare __comp, _Parallelism __parallelism)
1724     {
1725       typedef iterator_traits<_RAIter> _TraitsType;
1726       typedef typename _TraitsType::value_type _ValueType;
1727
1728       if (__begin != __end)
1729         {
1730           if (_GLIBCXX_PARALLEL_CONDITION(
1731                 static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin) >=
1732                 __gnu_parallel::_Settings::get().sort_minimal_n))
1733             __gnu_parallel::__parallel_sort<true>(__begin, __end,
1734                                                   __comp, __parallelism);
1735           else
1736             stable_sort(__begin, __end, __comp,
1737                         __gnu_parallel::sequential_tag());
1738         }
1739     }
1740
1741   // Public interface, insert default comparator
1742   template<typename _RAIter>
1743     inline void
1744     stable_sort(_RAIter __begin, _RAIter __end)
1745     {
1746       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1747       stable_sort(__begin, __end, std::less<_ValueType>(),
1748                   __gnu_parallel::default_parallel_tag());
1749     }
1750
1751   // Public interface, insert default comparator
1752   template<typename _RAIter>
1753     inline void
1754     stable_sort(_RAIter __begin, _RAIter __end,
1755                 __gnu_parallel::default_parallel_tag __parallelism)
1756     {
1757       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1758       stable_sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1759     }
1760
1761   // Public interface, insert default comparator
1762   template<typename _RAIter>
1763     inline void
1764     stable_sort(_RAIter __begin, _RAIter __end,
1765                 __gnu_parallel::parallel_tag __parallelism)
1766     {
1767       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1768       stable_sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1769     }
1770
1771   // Public interface, insert default comparator
1772   template<typename _RAIter>
1773     inline void
1774     stable_sort(_RAIter __begin, _RAIter __end,
1775                 __gnu_parallel::multiway_mergesort_tag __parallelism)
1776     {
1777       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1778       stable_sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1779     }
1780
1781   // Public interface, insert default comparator
1782   template<typename _RAIter>
1783     inline void
1784     stable_sort(_RAIter __begin, _RAIter __end,
1785                 __gnu_parallel::quicksort_tag __parallelism)
1786     {
1787       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1788       stable_sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1789     }
1790
1791   // Public interface, insert default comparator
1792   template<typename _RAIter>
1793     inline void
1794     stable_sort(_RAIter __begin, _RAIter __end,
1795                 __gnu_parallel::balanced_quicksort_tag __parallelism)
1796     {
1797       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1798       stable_sort(__begin, __end, std::less<_ValueType>(), __parallelism);
1799     }
1800
1801   // Public interface
1802   template<typename _RAIter, typename _Compare>
1803     void
1804     stable_sort(_RAIter __begin, _RAIter __end, _Compare __comp)
1805     {
1806       stable_sort(
1807         __begin, __end, __comp, __gnu_parallel::default_parallel_tag());
1808     }
1809
1810   // Sequential fallback
1811   template<typename _IIter1, typename _IIter2,
1812            typename _OutputIterator>
1813     inline _OutputIterator
1814     merge(_IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2,
1815           _IIter2 __end2, _OutputIterator __result,
1816           __gnu_parallel::sequential_tag)
1817     { return _GLIBCXX_STD_A::merge(
1818                __begin1, __end1, __begin2, __end2, __result); }
1819
1820   // Sequential fallback
1821   template<typename _IIter1, typename _IIter2,
1822            typename _OutputIterator, typename _Compare>
1823     inline _OutputIterator
1824     merge(_IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2,
1825           _IIter2 __end2, _OutputIterator __result, _Compare __comp,
1826           __gnu_parallel::sequential_tag)
1827     { return _GLIBCXX_STD_A::merge(
1828                 __begin1, __end1, __begin2, __end2, __result, __comp); }
1829
1830   // Sequential fallback for input iterator case
1831   template<typename _IIter1, typename _IIter2, typename _OutputIterator,
1832            typename _Compare, typename _IteratorTag1,
1833            typename _IteratorTag2, typename _IteratorTag3>
1834     inline _OutputIterator
1835     __merge_switch(_IIter1 __begin1, _IIter1 __end1,
1836                    _IIter2 __begin2, _IIter2 __end2,
1837                    _OutputIterator __result, _Compare __comp,
1838                    _IteratorTag1, _IteratorTag2, _IteratorTag3)
1839      { return _GLIBCXX_STD_A::merge(__begin1, __end1, __begin2, __end2,
1840                                     __result, __comp); }
1841
1842   // Parallel algorithm for random access iterators
1843   template<typename _IIter1, typename _IIter2,
1844            typename _OutputIterator, typename _Compare>
1845     _OutputIterator
1846     __merge_switch(_IIter1 __begin1, _IIter1 __end1,
1847                    _IIter2 __begin2, _IIter2 __end2,
1848                    _OutputIterator __result, _Compare __comp,
1849                    random_access_iterator_tag, random_access_iterator_tag,
1850                    random_access_iterator_tag)
1851     {
1852       if (_GLIBCXX_PARALLEL_CONDITION(
1853             (static_cast<__gnu_parallel::_SequenceIndex>(__end1 - __begin1)
1854              >= __gnu_parallel::_Settings::get().merge_minimal_n
1855              || static_cast<__gnu_parallel::_SequenceIndex>(__end2 - __begin2)
1856              >= __gnu_parallel::_Settings::get().merge_minimal_n)))
1857         return __gnu_parallel::__parallel_merge_advance(
1858                  __begin1, __end1, __begin2, __end2, __result,
1859                  (__end1 - __begin1) + (__end2 - __begin2), __comp);
1860       else
1861         return __gnu_parallel::__merge_advance(
1862                  __begin1, __end1, __begin2, __end2, __result,
1863                  (__end1 - __begin1) + (__end2 - __begin2), __comp);
1864   }
1865
1866   // Public interface
1867   template<typename _IIter1, typename _IIter2,
1868            typename _OutputIterator, typename _Compare>
1869     inline _OutputIterator
1870     merge(_IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2,
1871           _IIter2 __end2, _OutputIterator __result, _Compare __comp)
1872     {
1873       return __merge_switch(
1874                 __begin1, __end1, __begin2, __end2, __result, __comp,
1875                 std::__iterator_category(__begin1),
1876                 std::__iterator_category(__begin2),
1877                 std::__iterator_category(__result));
1878   }
1879
1880   // Public interface, insert default comparator
1881   template<typename _IIter1, typename _IIter2,
1882            typename _OutputIterator>
1883     inline _OutputIterator
1884     merge(_IIter1 __begin1, _IIter1 __end1, _IIter2 __begin2,
1885           _IIter2 __end2, _OutputIterator __result)
1886     {
1887       typedef typename std::iterator_traits<_IIter1>::value_type _ValueType1;
1888       typedef typename std::iterator_traits<_IIter2>::value_type _ValueType2;
1889
1890       return __gnu_parallel::merge(__begin1, __end1, __begin2, __end2,
1891                 __result, __gnu_parallel::_Less<_ValueType1, _ValueType2>());
1892     }
1893
1894   // Sequential fallback
1895   template<typename _RAIter>
1896     inline void
1897     nth_element(_RAIter __begin, _RAIter __nth,
1898                 _RAIter __end, __gnu_parallel::sequential_tag)
1899     { return _GLIBCXX_STD_A::nth_element(__begin, __nth, __end); }
1900
1901   // Sequential fallback
1902   template<typename _RAIter, typename _Compare>
1903     inline void
1904     nth_element(_RAIter __begin, _RAIter __nth,
1905                 _RAIter __end, _Compare __comp,
1906                 __gnu_parallel::sequential_tag)
1907     { return _GLIBCXX_STD_A::nth_element(__begin, __nth, __end, __comp); }
1908
1909   // Public interface
1910   template<typename _RAIter, typename _Compare>
1911     inline void
1912     nth_element(_RAIter __begin, _RAIter __nth,
1913                 _RAIter __end, _Compare __comp)
1914     {
1915       if (_GLIBCXX_PARALLEL_CONDITION(
1916             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1917             >= __gnu_parallel::_Settings::get().nth_element_minimal_n))
1918         __gnu_parallel::__parallel_nth_element(__begin, __nth, __end, __comp);
1919       else
1920         nth_element(__begin, __nth, __end, __comp,
1921                     __gnu_parallel::sequential_tag());
1922     }
1923
1924   // Public interface, insert default comparator
1925   template<typename _RAIter>
1926     inline void
1927     nth_element(_RAIter __begin, _RAIter __nth,
1928                 _RAIter __end)
1929     {
1930       typedef typename iterator_traits<_RAIter>::value_type _ValueType;
1931       __gnu_parallel::nth_element(__begin, __nth, __end,
1932                                   std::less<_ValueType>());
1933     }
1934
1935   // Sequential fallback
1936   template<typename _RAIter, typename _Compare>
1937     inline void
1938     partial_sort(_RAIter __begin, _RAIter __middle,
1939                  _RAIter __end, _Compare __comp,
1940                  __gnu_parallel::sequential_tag)
1941     { _GLIBCXX_STD_A::partial_sort(__begin, __middle, __end, __comp); }
1942
1943   // Sequential fallback
1944   template<typename _RAIter>
1945     inline void
1946     partial_sort(_RAIter __begin, _RAIter __middle,
1947                  _RAIter __end, __gnu_parallel::sequential_tag)
1948     { _GLIBCXX_STD_A::partial_sort(__begin, __middle, __end); }
1949
1950   // Public interface, parallel algorithm for random access iterators
1951   template<typename _RAIter, typename _Compare>
1952     void
1953     partial_sort(_RAIter __begin, _RAIter __middle,
1954                  _RAIter __end, _Compare __comp)
1955     {
1956       if (_GLIBCXX_PARALLEL_CONDITION(
1957             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
1958             >= __gnu_parallel::_Settings::get().partial_sort_minimal_n))
1959         __gnu_parallel::
1960           __parallel_partial_sort(__begin, __middle, __end, __comp);
1961       else
1962         partial_sort(__begin, __middle, __end, __comp,
1963                      __gnu_parallel::sequential_tag());
1964     }
1965
1966   // Public interface, insert default comparator
1967   template<typename _RAIter>
1968     inline void
1969     partial_sort(_RAIter __begin, _RAIter __middle,
1970                  _RAIter __end)
1971     {
1972       typedef iterator_traits<_RAIter> _TraitsType;
1973       typedef typename _TraitsType::value_type _ValueType;
1974       __gnu_parallel::partial_sort(__begin, __middle, __end,
1975                                    std::less<_ValueType>());
1976     }
1977
1978   // Sequential fallback
1979   template<typename _FIterator>
1980     inline _FIterator
1981     max_element(_FIterator __begin, _FIterator __end,
1982                 __gnu_parallel::sequential_tag)
1983     { return _GLIBCXX_STD_A::max_element(__begin, __end); }
1984
1985   // Sequential fallback
1986   template<typename _FIterator, typename _Compare>
1987     inline _FIterator
1988     max_element(_FIterator __begin, _FIterator __end, _Compare __comp,
1989                 __gnu_parallel::sequential_tag)
1990     { return _GLIBCXX_STD_A::max_element(__begin, __end, __comp); }
1991
1992   // Sequential fallback for input iterator case
1993   template<typename _FIterator, typename _Compare, typename _IteratorTag>
1994     inline _FIterator
1995     __max_element_switch(_FIterator __begin, _FIterator __end,
1996                        _Compare __comp, _IteratorTag)
1997     { return max_element(__begin, __end, __comp,
1998                          __gnu_parallel::sequential_tag()); }
1999
2000   // Parallel algorithm for random access iterators
2001   template<typename _RAIter, typename _Compare>
2002     _RAIter
2003     __max_element_switch(_RAIter __begin, _RAIter __end,
2004                          _Compare __comp, random_access_iterator_tag,
2005                          __gnu_parallel::_Parallelism __parallelism_tag)
2006     {
2007       if (_GLIBCXX_PARALLEL_CONDITION(
2008             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
2009             >= __gnu_parallel::_Settings::get().max_element_minimal_n
2010             && __gnu_parallel::__is_parallel(__parallelism_tag)))
2011         {
2012           _RAIter __res(__begin);
2013           __gnu_parallel::__identity_selector<_RAIter>
2014             __functionality;
2015           __gnu_parallel::
2016             __for_each_template_random_access(
2017               __begin, __end, __gnu_parallel::_Nothing(), __functionality,
2018               __gnu_parallel::__max_element_reduct<_Compare, _RAIter>(__comp),
2019               __res, __res, -1, __parallelism_tag);
2020           return __res;
2021         }
2022       else
2023         return max_element(__begin, __end, __comp,
2024                            __gnu_parallel::sequential_tag());
2025     }
2026
2027   // Public interface, insert default comparator
2028   template<typename _FIterator>
2029     inline _FIterator
2030     max_element(_FIterator __begin, _FIterator __end,
2031                 __gnu_parallel::_Parallelism __parallelism_tag)
2032     {
2033       typedef typename iterator_traits<_FIterator>::value_type _ValueType;
2034       return max_element(__begin, __end, std::less<_ValueType>(),
2035                          __parallelism_tag);
2036     }
2037
2038   template<typename _FIterator>
2039     inline _FIterator
2040     max_element(_FIterator __begin, _FIterator __end)
2041     {
2042       typedef typename iterator_traits<_FIterator>::value_type _ValueType;
2043       return __gnu_parallel::max_element(__begin, __end,
2044                                          std::less<_ValueType>());
2045     }
2046
2047   // Public interface
2048   template<typename _FIterator, typename _Compare>
2049     inline _FIterator
2050     max_element(_FIterator __begin, _FIterator __end, _Compare __comp,
2051                 __gnu_parallel::_Parallelism __parallelism_tag)
2052     {
2053       return __max_element_switch(__begin, __end, __comp,
2054                                   std::__iterator_category(__begin),
2055                                   __parallelism_tag);
2056     }
2057
2058   template<typename _FIterator, typename _Compare>
2059     inline _FIterator
2060     max_element(_FIterator __begin, _FIterator __end, _Compare __comp)
2061     {
2062       return __max_element_switch(__begin, __end, __comp,
2063                                   std::__iterator_category(__begin));
2064     }
2065
2066
2067   // Sequential fallback
2068   template<typename _FIterator>
2069     inline _FIterator
2070     min_element(_FIterator __begin, _FIterator __end,
2071                 __gnu_parallel::sequential_tag)
2072     { return _GLIBCXX_STD_A::min_element(__begin, __end); }
2073
2074   // Sequential fallback
2075   template<typename _FIterator, typename _Compare>
2076     inline _FIterator
2077     min_element(_FIterator __begin, _FIterator __end, _Compare __comp,
2078                 __gnu_parallel::sequential_tag)
2079     { return _GLIBCXX_STD_A::min_element(__begin, __end, __comp); }
2080
2081   // Sequential fallback for input iterator case
2082   template<typename _FIterator, typename _Compare, typename _IteratorTag>
2083     inline _FIterator
2084     __min_element_switch(_FIterator __begin, _FIterator __end,
2085                        _Compare __comp, _IteratorTag)
2086     { return min_element(__begin, __end, __comp,
2087                          __gnu_parallel::sequential_tag()); }
2088
2089   // Parallel algorithm for random access iterators
2090   template<typename _RAIter, typename _Compare>
2091     _RAIter
2092     __min_element_switch(_RAIter __begin, _RAIter __end,
2093                          _Compare __comp, random_access_iterator_tag,
2094                          __gnu_parallel::_Parallelism __parallelism_tag)
2095     {
2096       if (_GLIBCXX_PARALLEL_CONDITION(
2097             static_cast<__gnu_parallel::_SequenceIndex>(__end - __begin)
2098             >= __gnu_parallel::_Settings::get().min_element_minimal_n
2099             && __gnu_parallel::__is_parallel(__parallelism_tag)))
2100         {
2101           _RAIter __res(__begin);
2102           __gnu_parallel::__identity_selector<_RAIter>
2103             __functionality;
2104           __gnu_parallel::
2105             __for_each_template_random_access(
2106               __begin, __end, __gnu_parallel::_Nothing(), __functionality,
2107               __gnu_parallel::__min_element_reduct<_Compare, _RAIter>(__comp),
2108               __res, __res, -1, __parallelism_tag);
2109           return __res;
2110         }
2111       else
2112         return min_element(__begin, __end, __comp,
2113                            __gnu_parallel::sequential_tag());
2114     }
2115
2116   // Public interface, insert default comparator
2117   template<typename _FIterator>
2118     inline _FIterator
2119     min_element(_FIterator __begin, _FIterator __end,
2120                 __gnu_parallel::_Parallelism __parallelism_tag)
2121     {
2122       typedef typename iterator_traits<_FIterator>::value_type _ValueType;
2123       return min_element(__begin, __end, std::less<_ValueType>(),
2124                          __parallelism_tag);
2125     }
2126
2127   template<typename _FIterator>
2128     inline _FIterator
2129     min_element(_FIterator __begin, _FIterator __end)
2130     {
2131       typedef typename iterator_traits<_FIterator>::value_type _ValueType;
2132       return __gnu_parallel::min_element(__begin, __end,
2133                                          std::less<_ValueType>());
2134     }
2135
2136   // Public interface
2137   template<typename _FIterator, typename _Compare>
2138     inline _FIterator
2139     min_element(_FIterator __begin, _FIterator __end, _Compare __comp,
2140                 __gnu_parallel::_Parallelism __parallelism_tag)
2141     {
2142       return __min_element_switch(__begin, __end, __comp,
2143                                   std::__iterator_category(__begin),
2144                                   __parallelism_tag);
2145     }
2146
2147   template<typename _FIterator, typename _Compare>
2148     inline _FIterator
2149     min_element(_FIterator __begin, _FIterator __end, _Compare __comp)
2150     {
2151       return __min_element_switch(__begin, __end, __comp,
2152                                   std::__iterator_category(__begin));
2153     }
2154
2155 #if __cplusplus >= 201703L
2156   using _GLIBCXX_STD_A::for_each_n;
2157   using _GLIBCXX_STD_A::sample;
2158 #endif
2159 } // end namespace
2160 } // end namespace
2161
2162 #endif /* _GLIBCXX_PARALLEL_ALGO_H */