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

   1 // Core algorithmic facilities -*- C++ -*-
   2
   3 // Copyright (C) 2020 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/ranges_algobase.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{algorithm}
  28  */
  29
  30 #ifndef _RANGES_ALGOBASE_H
  31 #define _RANGES_ALGOBASE_H 1
  32
  33 #if __cplusplus > 201703L
  34
  35 #include <compare>
  36 #include <iterator>
  37 // #include <bits/range_concepts.h>
  38 #include <ranges>
  39 #include <bits/invoke.h>
  40 #include <bits/cpp_type_traits.h> // __is_byte
  41
  42 #if __cpp_lib_concepts
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46 namespace ranges
  47 {
  48   namespace __detail
  49   {
  50     template<typename _Tp>
  51       constexpr inline bool __is_normal_iterator = false;
  52
  53     template<typename _Iterator, typename _Container>
  54       constexpr inline bool
  55         __is_normal_iterator<__gnu_cxx::__normal_iterator<_Iterator,
  56                                                           _Container>> = true;
  57
  58     template<typename _Tp>
  59       constexpr inline bool __is_reverse_iterator = false;
  60
  61     template<typename _Iterator>
  62       constexpr inline bool
  63         __is_reverse_iterator<reverse_iterator<_Iterator>> = true;
  64
  65     template<typename _Tp>
  66       constexpr inline bool __is_move_iterator = false;
  67
  68     template<typename _Iterator>
  69       constexpr inline bool
  70         __is_move_iterator<move_iterator<_Iterator>> = true;
  71   } // namespace __detail
  72
  73   struct __equal_fn
  74   {
  75     template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
  76              input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
  77              typename _Pred = ranges::equal_to,
  78              typename _Proj1 = identity, typename _Proj2 = identity>
  79       requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
  80       constexpr bool
  81       operator()(_Iter1 __first1, _Sent1 __last1,
  82                  _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
  83                  _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
  84       {
  85         // TODO: implement more specializations to at least have parity with
  86         // std::equal.
  87         if constexpr (__detail::__is_normal_iterator<_Iter1>
  88                       && same_as<_Iter1, _Sent1>)
  89           return (*this)(__first1.base(), __last1.base(),
  90                          std::move(__first2), std::move(__last2),
  91                          std::move(__pred),
  92                          std::move(__proj1), std::move(__proj2));
  93         else if constexpr (__detail::__is_normal_iterator<_Iter2>
  94                            && same_as<_Iter2, _Sent2>)
  95           return (*this)(std::move(__first1), std::move(__last1),
  96                          __first2.base(), __last2.base(),
  97                          std::move(__pred),
  98                          std::move(__proj1), std::move(__proj2));
  99         else if constexpr (sized_sentinel_for<_Sent1, _Iter1>
 100                            && sized_sentinel_for<_Sent2, _Iter2>)
 101           {
 102             auto __d1 = ranges::distance(__first1, __last1);
 103             auto __d2 = ranges::distance(__first2, __last2);
 104             if (__d1 != __d2)
 105               return false;
 106
 107             using _ValueType1 = iter_value_t<_Iter1>;
 108             constexpr bool __use_memcmp
 109               = ((is_integral_v<_ValueType1> || is_pointer_v<_ValueType1>)
 110                  && __memcmpable<_Iter1, _Iter2>::__value
 111                  && is_same_v<_Pred, ranges::equal_to>
 112                  && is_same_v<_Proj1, identity>
 113                  && is_same_v<_Proj2, identity>);
 114             if constexpr (__use_memcmp)
 115               {
 116                 if (const size_t __len = (__last1 - __first1))
 117                   return !std::__memcmp(__first1, __first2, __len);
 118                 return true;
 119               }
 120             else
 121               {
 122                 for (; __first1 != __last1; ++__first1, (void)++__first2)
 123                   if (!(bool)std::__invoke(__pred,
 124                                            std::__invoke(__proj1, *__first1),
 125                                            std::__invoke(__proj2, *__first2)))
 126                     return false;
 127                 return true;
 128               }
 129           }
 130         else
 131           {
 132             for (; __first1 != __last1 && __first2 != __last2;
 133                  ++__first1, (void)++__first2)
 134               if (!(bool)std::__invoke(__pred,
 135                                        std::__invoke(__proj1, *__first1),
 136                                        std::__invoke(__proj2, *__first2)))
 137                 return false;
 138             return __first1 == __last1 && __first2 == __last2;
 139           }
 140       }
 141
 142     template<input_range _Range1, input_range _Range2,
 143              typename _Pred = ranges::equal_to,
 144              typename _Proj1 = identity, typename _Proj2 = identity>
 145       requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
 146                                      _Pred, _Proj1, _Proj2>
 147       constexpr bool
 148       operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
 149                  _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
 150       {
 151         return (*this)(ranges::begin(__r1), ranges::end(__r1),
 152                        ranges::begin(__r2), ranges::end(__r2),
 153                        std::move(__pred),
 154                        std::move(__proj1), std::move(__proj2));
 155       }
 156   };
 157
 158   inline constexpr __equal_fn equal{};
 159
 160   template<typename _Iter, typename _Out>
 161     struct in_out_result
 162     {
 163       [[no_unique_address]] _Iter in;
 164       [[no_unique_address]] _Out out;
 165
 166       template<typename _Iter2, typename _Out2>
 167         requires convertible_to<const _Iter&, _Iter2>
 168           && convertible_to<const _Out&, _Out2>
 169         constexpr
 170         operator in_out_result<_Iter2, _Out2>() const &
 171         { return {in, out}; }
 172
 173       template<typename _Iter2, typename _Out2>
 174         requires convertible_to<_Iter, _Iter2>
 175           && convertible_to<_Out, _Out2>
 176         constexpr
 177         operator in_out_result<_Iter2, _Out2>() &&
 178         { return {std::move(in), std::move(out)}; }
 179     };
 180
 181   template<typename _Iter, typename _Out>
 182     using copy_result = in_out_result<_Iter, _Out>;
 183
 184   template<typename _Iter, typename _Out>
 185     using move_result = in_out_result<_Iter, _Out>;
 186
 187   template<typename _Iter1, typename _Iter2>
 188     using move_backward_result = in_out_result<_Iter1, _Iter2>;
 189
 190   template<typename _Iter1, typename _Iter2>
 191     using copy_backward_result = in_out_result<_Iter1, _Iter2>;
 192
 193   template<bool _IsMove,
 194            bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
 195            bidirectional_iterator _Out>
 196     requires (_IsMove
 197               ? indirectly_movable<_Iter, _Out>
 198               : indirectly_copyable<_Iter, _Out>)
 199     constexpr conditional_t<_IsMove,
 200                             move_backward_result<_Iter, _Out>,
 201                             copy_backward_result<_Iter, _Out>>
 202     __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result);
 203
 204   template<bool _IsMove,
 205            input_iterator _Iter, sentinel_for<_Iter> _Sent,
 206            weakly_incrementable _Out>
 207     requires (_IsMove
 208               ? indirectly_movable<_Iter, _Out>
 209               : indirectly_copyable<_Iter, _Out>)
 210     constexpr conditional_t<_IsMove,
 211                             move_result<_Iter, _Out>,
 212                             copy_result<_Iter, _Out>>
 213     __copy_or_move(_Iter __first, _Sent __last, _Out __result)
 214     {
 215       // TODO: implement more specializations to be at least on par with
 216       // std::copy/std::move.
 217       using __detail::__is_move_iterator;
 218       using __detail::__is_reverse_iterator;
 219       using __detail::__is_normal_iterator;
 220       if constexpr (__is_move_iterator<_Iter> && same_as<_Iter, _Sent>)
 221         {
 222           auto [__in, __out]
 223             = ranges::__copy_or_move<true>(std::move(__first).base(),
 224                                            std::move(__last).base(),
 225                                            std::move(__result));
 226           return {move_iterator{std::move(__in)}, std::move(__out)};
 227         }
 228       else if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent>
 229                          && __is_reverse_iterator<_Out>)
 230         {
 231           auto [__in,__out]
 232             = ranges::__copy_or_move_backward<_IsMove>(std::move(__last).base(),
 233                                                        std::move(__first).base(),
 234                                                        std::move(__result).base());
 235           return {reverse_iterator{std::move(__in)},
 236                   reverse_iterator{std::move(__out)}};
 237         }
 238       else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>)
 239         {
 240           auto [__in,__out]
 241             = ranges::__copy_or_move<_IsMove>(__first.base(), __last.base(),
 242                                               __result);
 243           return {decltype(__first){__in}, std::move(__out)};
 244         }
 245       else if constexpr (__is_normal_iterator<_Out>)
 246         {
 247           auto [__in,__out]
 248             = ranges::__copy_or_move<_IsMove>(__first, __last, __result.base());
 249           return {std::move(__in), decltype(__result){__out}};
 250         }
 251       else if constexpr (sized_sentinel_for<_Sent, _Iter>)
 252         {
 253 #ifdef __cpp_lib_is_constant_evaluated
 254           if (!std::is_constant_evaluated())
 255 #endif
 256             {
 257               if constexpr (__memcpyable<_Iter, _Out>::__value)
 258                 {
 259                   using _ValueTypeI = iter_value_t<_Iter>;
 260                   static_assert(_IsMove
 261                       ? is_move_assignable_v<_ValueTypeI>
 262                       : is_copy_assignable_v<_ValueTypeI>);
 263                   auto __num = __last - __first;
 264                   if (__num)
 265                     __builtin_memmove(__result, __first,
 266                         sizeof(_ValueTypeI) * __num);
 267                   return {__first + __num, __result + __num};
 268                 }
 269             }
 270
 271           for (auto __n = __last - __first; __n > 0; --__n)
 272             {
 273               if constexpr (_IsMove)
 274                 *__result = std::move(*__first);
 275               else
 276                 *__result = *__first;
 277               ++__first;
 278               ++__result;
 279             }
 280           return {std::move(__first), std::move(__result)};
 281         }
 282       else
 283         {
 284           while (__first != __last)
 285             {
 286               if constexpr (_IsMove)
 287                 *__result = std::move(*__first);
 288               else
 289                 *__result = *__first;
 290               ++__first;
 291               ++__result;
 292             }
 293           return {std::move(__first), std::move(__result)};
 294         }
 295     }
 296
 297   struct __copy_fn
 298   {
 299     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 300              weakly_incrementable _Out>
 301       requires indirectly_copyable<_Iter, _Out>
 302       constexpr copy_result<_Iter, _Out>
 303       operator()(_Iter __first, _Sent __last, _Out __result) const
 304       {
 305         return ranges::__copy_or_move<false>(std::move(__first),
 306                                              std::move(__last),
 307                                              std::move(__result));
 308       }
 309
 310     template<input_range _Range, weakly_incrementable _Out>
 311       requires indirectly_copyable<iterator_t<_Range>, _Out>
 312       constexpr copy_result<borrowed_iterator_t<_Range>, _Out>
 313       operator()(_Range&& __r, _Out __result) const
 314       {
 315         return (*this)(ranges::begin(__r), ranges::end(__r),
 316                        std::move(__result));
 317       }
 318   };
 319
 320   inline constexpr __copy_fn copy{};
 321
 322   struct __move_fn
 323   {
 324     template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
 325              weakly_incrementable _Out>
 326       requires indirectly_movable<_Iter, _Out>
 327       constexpr move_result<_Iter, _Out>
 328       operator()(_Iter __first, _Sent __last, _Out __result) const
 329       {
 330         return ranges::__copy_or_move<true>(std::move(__first),
 331                                             std::move(__last),
 332                                             std::move(__result));
 333       }
 334
 335     template<input_range _Range, weakly_incrementable _Out>
 336       requires indirectly_movable<iterator_t<_Range>, _Out>
 337       constexpr move_result<borrowed_iterator_t<_Range>, _Out>
 338       operator()(_Range&& __r, _Out __result) const
 339       {
 340         return (*this)(ranges::begin(__r), ranges::end(__r),
 341                        std::move(__result));
 342       }
 343   };
 344
 345   inline constexpr __move_fn move{};
 346
 347   template<bool _IsMove,
 348            bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
 349            bidirectional_iterator _Out>
 350     requires (_IsMove
 351               ? indirectly_movable<_Iter, _Out>
 352               : indirectly_copyable<_Iter, _Out>)
 353     constexpr conditional_t<_IsMove,
 354                             move_backward_result<_Iter, _Out>,
 355                             copy_backward_result<_Iter, _Out>>
 356     __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result)
 357     {
 358       // TODO: implement more specializations to be at least on par with
 359       // std::copy_backward/std::move_backward.
 360       using __detail::__is_reverse_iterator;
 361       using __detail::__is_normal_iterator;
 362       if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent>
 363                     && __is_reverse_iterator<_Out>)
 364         {
 365           auto [__in,__out]
 366             = ranges::__copy_or_move<_IsMove>(std::move(__last).base(),
 367                                               std::move(__first).base(),
 368                                               std::move(__result).base());
 369           return {reverse_iterator{std::move(__in)},
 370                   reverse_iterator{std::move(__out)}};
 371         }
 372       else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>)
 373         {
 374           auto [__in,__out]
 375             = ranges::__copy_or_move_backward<_IsMove>(__first.base(),
 376                                                        __last.base(),
 377                                                        std::move(__result));
 378           return {decltype(__first){__in}, std::move(__out)};
 379         }
 380       else if constexpr (__is_normal_iterator<_Out>)
 381         {
 382           auto [__in,__out]
 383             = ranges::__copy_or_move_backward<_IsMove>(std::move(__first),
 384                                                        std::move(__last),
 385                                                        __result.base());
 386           return {std::move(__in), decltype(__result){__out}};
 387         }
 388       else if constexpr (sized_sentinel_for<_Sent, _Iter>)
 389         {
 390 #ifdef __cpp_lib_is_constant_evaluated
 391           if (!std::is_constant_evaluated())
 392 #endif
 393             {
 394               if constexpr (__memcpyable<_Out, _Iter>::__value)
 395                 {
 396                   using _ValueTypeI = iter_value_t<_Iter>;
 397                   static_assert(_IsMove
 398                       ? is_move_assignable_v<_ValueTypeI>
 399                       : is_copy_assignable_v<_ValueTypeI>);
 400                   auto __num = __last - __first;
 401                   if (__num)
 402                     __builtin_memmove(__result - __num, __first,
 403                                       sizeof(_ValueTypeI) * __num);
 404                   return {__first + __num, __result - __num};
 405                 }
 406             }
 407
 408           auto __lasti = ranges::next(__first, __last);
 409           auto __tail = __lasti;
 410
 411           for (auto __n = __last - __first; __n > 0; --__n)
 412             {
 413               --__tail;
 414               --__result;
 415               if constexpr (_IsMove)
 416                 *__result = std::move(*__tail);
 417               else
 418                 *__result = *__tail;
 419             }
 420           return {std::move(__lasti), std::move(__result)};
 421         }
 422       else
 423         {
 424           auto __lasti = ranges::next(__first, __last);
 425           auto __tail = __lasti;
 426
 427           while (__first != __tail)
 428             {
 429               --__tail;
 430               --__result;
 431               if constexpr (_IsMove)
 432                 *__result = std::move(*__tail);
 433               else
 434                 *__result = *__tail;
 435             }
 436           return {std::move(__lasti), std::move(__result)};
 437         }
 438     }
 439
 440   struct __copy_backward_fn
 441   {
 442     template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
 443              bidirectional_iterator _Iter2>
 444       requires indirectly_copyable<_Iter1, _Iter2>
 445       constexpr copy_backward_result<_Iter1, _Iter2>
 446       operator()(_Iter1 __first, _Sent1 __last, _Iter2 __result) const
 447       {
 448         return ranges::__copy_or_move_backward<false>(std::move(__first),
 449                                                       std::move(__last),
 450                                                       std::move(__result));
 451       }
 452
 453     template<bidirectional_range _Range, bidirectional_iterator _Iter>
 454       requires indirectly_copyable<iterator_t<_Range>, _Iter>
 455       constexpr copy_backward_result<borrowed_iterator_t<_Range>, _Iter>
 456       operator()(_Range&& __r, _Iter __result) const
 457       {
 458         return (*this)(ranges::begin(__r), ranges::end(__r),
 459                        std::move(__result));
 460       }
 461   };
 462
 463   inline constexpr __copy_backward_fn copy_backward{};
 464
 465   struct __move_backward_fn
 466   {
 467     template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
 468              bidirectional_iterator _Iter2>
 469       requires indirectly_movable<_Iter1, _Iter2>
 470       constexpr move_backward_result<_Iter1, _Iter2>
 471       operator()(_Iter1 __first, _Sent1 __last, _Iter2 __result) const
 472       {
 473         return ranges::__copy_or_move_backward<true>(std::move(__first),
 474                                                      std::move(__last),
 475                                                      std::move(__result));
 476       }
 477
 478     template<bidirectional_range _Range, bidirectional_iterator _Iter>
 479       requires indirectly_movable<iterator_t<_Range>, _Iter>
 480       constexpr move_backward_result<borrowed_iterator_t<_Range>, _Iter>
 481       operator()(_Range&& __r, _Iter __result) const
 482       {
 483         return (*this)(ranges::begin(__r), ranges::end(__r),
 484                        std::move(__result));
 485       }
 486   };
 487
 488   inline constexpr __move_backward_fn move_backward{};
 489
 490   template<typename _Iter, typename _Out>
 491     using copy_n_result = in_out_result<_Iter, _Out>;
 492
 493   struct __copy_n_fn
 494   {
 495     template<input_iterator _Iter, weakly_incrementable _Out>
 496       requires indirectly_copyable<_Iter, _Out>
 497       constexpr copy_n_result<_Iter, _Out>
 498       operator()(_Iter __first, iter_difference_t<_Iter> __n,
 499                  _Out __result) const
 500       {
 501         if constexpr (random_access_iterator<_Iter>)
 502           {
 503             if (__n > 0)
 504               return ranges::copy(__first, __first + __n, std::move(__result));
 505           }
 506         else
 507           {
 508             for (; __n > 0; --__n, (void)++__result, (void)++__first)
 509               *__result = *__first;
 510           }
 511         return {std::move(__first), std::move(__result)};
 512       }
 513   };
 514
 515   inline constexpr __copy_n_fn copy_n{};
 516
 517   struct __fill_n_fn
 518   {
 519     template<typename _Tp, output_iterator<const _Tp&> _Out>
 520       constexpr _Out
 521       operator()(_Out __first, iter_difference_t<_Out> __n,
 522                  const _Tp& __value) const
 523       {
 524         // TODO: implement more specializations to be at least on par with
 525         // std::fill_n
 526         if (__n <= 0)
 527           return __first;
 528
 529         // TODO: Generalize this optimization to contiguous iterators.
 530         if constexpr (is_pointer_v<_Out>
 531                       // Note that __is_byte already implies !is_volatile.
 532                       && __is_byte<remove_pointer_t<_Out>>::__value
 533                       && integral<_Tp>)
 534           {
 535             __builtin_memset(__first, static_cast<unsigned char>(__value), __n);
 536             return __first + __n;
 537           }
 538         else if constexpr (is_scalar_v<_Tp>)
 539           {
 540             const auto __tmp = __value;
 541             for (; __n > 0; --__n, (void)++__first)
 542               *__first = __tmp;
 543             return __first;
 544           }
 545         else
 546           {
 547             for (; __n > 0; --__n, (void)++__first)
 548               *__first = __value;
 549             return __first;
 550           }
 551       }
 552   };
 553
 554   inline constexpr __fill_n_fn fill_n{};
 555
 556   struct __fill_fn
 557   {
 558     template<typename _Tp,
 559              output_iterator<const _Tp&> _Out, sentinel_for<_Out> _Sent>
 560       constexpr _Out
 561       operator()(_Out __first, _Sent __last, const _Tp& __value) const
 562       {
 563         // TODO: implement more specializations to be at least on par with
 564         // std::fill
 565         if constexpr (sized_sentinel_for<_Sent, _Out>)
 566           {
 567             const auto __len = __last - __first;
 568             return ranges::fill_n(__first, __len, __value);
 569           }
 570         else if constexpr (is_scalar_v<_Tp>)
 571           {
 572             const auto __tmp = __value;
 573             for (; __first != __last; ++__first)
 574               *__first = __tmp;
 575             return __first;
 576           }
 577         else
 578           {
 579             for (; __first != __last; ++__first)
 580               *__first = __value;
 581             return __first;
 582           }
 583       }
 584
 585     template<typename _Tp, output_range<const _Tp&> _Range>
 586       constexpr borrowed_iterator_t<_Range>
 587       operator()(_Range&& __r, const _Tp& __value) const
 588       {
 589         return (*this)(ranges::begin(__r), ranges::end(__r), __value);
 590       }
 591   };
 592
 593   inline constexpr __fill_fn fill{};
 594 }
 595 _GLIBCXX_END_NAMESPACE_VERSION
 596 } // namespace std
 597 #endif // concepts
 598 #endif // C++20
 599 #endif // _RANGES_ALGOBASE_H