1 // Concepts and traits for use with iterators -*- C++ -*- 2 3 // Copyright (C) 2019-2020 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/iterator_concepts.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{iterator} 28 */ 29 30 #ifndef _ITERATOR_CONCEPTS_H 31 #define _ITERATOR_CONCEPTS_H 1 32 33 #pragma GCC system_header 34 35 #include <concepts> 36 #include <bits/ptr_traits.h> // to_address 37 #include <bits/range_cmp.h> // identity, ranges::less 38 39 #if __cpp_lib_concepts 40 namespace std _GLIBCXX_VISIBILITY(default) 41 { 42 _GLIBCXX_BEGIN_NAMESPACE_VERSION 43 44 struct input_iterator_tag; 45 struct output_iterator_tag; 46 struct forward_iterator_tag; 47 struct bidirectional_iterator_tag; 48 struct random_access_iterator_tag; 49 struct contiguous_iterator_tag; 50 51 template<typename _Iterator> 52 struct iterator_traits; 53 54 template<typename _Tp> requires is_object_v<_Tp> 55 struct iterator_traits<_Tp*>; 56 57 template<typename _Iterator, typename> 58 struct __iterator_traits; 59 60 namespace __detail 61 { 62 template<typename _Tp> 63 using __with_ref = _Tp&; 64 65 template<typename _Tp> 66 concept __can_reference = requires { typename __with_ref<_Tp>; }; 67 68 template<typename _Tp> 69 concept __dereferenceable = requires(_Tp& __t) 70 { 71 { *__t } -> __can_reference; 72 }; 73 } // namespace __detail 74 75 template<__detail::__dereferenceable _Tp> 76 using iter_reference_t = decltype(*std::declval<_Tp&>()); 77 78 namespace ranges 79 { 80 namespace __cust_imove 81 { 82 void iter_move(); 83 84 template<typename _Tp> 85 concept __adl_imove 86 = (std::__detail::__class_or_enum<remove_reference_t<_Tp>>) 87 && requires(_Tp&& __t) { iter_move(static_cast<_Tp&&>(__t)); }; 88 89 struct _IMove 90 { 91 private: 92 template<typename _Tp> 93 struct __result 94 { using type = iter_reference_t<_Tp>; }; 95 96 template<typename _Tp> 97 requires __adl_imove<_Tp> 98 struct __result<_Tp> 99 { using type = decltype(iter_move(std::declval<_Tp>())); }; 100 101 template<typename _Tp> 102 requires (!__adl_imove<_Tp>) 103 && is_lvalue_reference_v<iter_reference_t<_Tp>> 104 struct __result<_Tp> 105 { using type = remove_reference_t<iter_reference_t<_Tp>>&&; }; 106 107 template<typename _Tp> 108 static constexpr bool 109 _S_noexcept() 110 { 111 if constexpr (__adl_imove<_Tp>) 112 return noexcept(iter_move(std::declval<_Tp>())); 113 else 114 return noexcept(*std::declval<_Tp>()); 115 } 116 117 public: 118 // The result type of iter_move(std::declval<_Tp>()) 119 template<std::__detail::__dereferenceable _Tp> 120 using __type = typename __result<_Tp>::type; 121 122 template<std::__detail::__dereferenceable _Tp> 123 constexpr __type<_Tp> 124 operator()(_Tp&& __e) const 125 noexcept(_S_noexcept<_Tp>()) 126 { 127 if constexpr (__adl_imove<_Tp>) 128 return iter_move(static_cast<_Tp&&>(__e)); 129 else if constexpr (is_lvalue_reference_v<iter_reference_t<_Tp>>) 130 return static_cast<__type<_Tp>>(*__e); 131 else 132 return *__e; 133 } 134 }; 135 } // namespace __cust_imove 136 137 inline namespace __cust 138 { 139 inline constexpr __cust_imove::_IMove iter_move{}; 140 } // inline namespace __cust 141 } // namespace ranges 142 143 template<__detail::__dereferenceable _Tp> 144 requires requires(_Tp& __t) 145 { { ranges::iter_move(__t) } -> __detail::__can_reference; } 146 using iter_rvalue_reference_t 147 = decltype(ranges::iter_move(std::declval<_Tp&>())); 148 149 template<typename> struct incrementable_traits { }; 150 151 template<typename _Tp> requires is_object_v<_Tp> 152 struct incrementable_traits<_Tp*> 153 { using difference_type = ptrdiff_t; }; 154 155 template<typename _Iter> 156 struct incrementable_traits<const _Iter> 157 : incrementable_traits<_Iter> { }; 158 159 template<typename _Tp> requires requires { typename _Tp::difference_type; } 160 struct incrementable_traits<_Tp> 161 { using difference_type = typename _Tp::difference_type; }; 162 163 template<typename _Tp> 164 requires (!requires { typename _Tp::difference_type; } 165 && requires(const _Tp& __a, const _Tp& __b) 166 { 167 requires (!is_void_v<remove_pointer_t<_Tp>>); // PR c++/78173 168 { __a - __b } -> integral; 169 }) 170 struct incrementable_traits<_Tp> 171 { 172 using difference_type 173 = make_signed_t<decltype(std::declval<_Tp>() - std::declval<_Tp>())>; 174 }; 175 176 #if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ 177 // __int128 is incrementable even if !integral<__int128> 178 template<> 179 struct incrementable_traits<__int128> 180 { using difference_type = __int128; }; 181 182 template<> 183 struct incrementable_traits<unsigned __int128> 184 { using difference_type = __int128; }; 185 #endif 186 187 namespace __detail 188 { 189 // An iterator such that iterator_traits<_Iter> names a specialization 190 // generated from the primary template. 191 template<typename _Iter> 192 concept __primary_traits_iter 193 = __is_base_of(__iterator_traits<_Iter, void>, iterator_traits<_Iter>); 194 195 template<typename _Iter, typename _Tp> 196 struct __iter_traits_impl 197 { using type = iterator_traits<_Iter>; }; 198 199 template<typename _Iter, typename _Tp> 200 requires __primary_traits_iter<_Iter> 201 struct __iter_traits_impl<_Iter, _Tp> 202 { using type = _Tp; }; 203 204 // ITER_TRAITS 205 template<typename _Iter, typename _Tp = _Iter> 206 using __iter_traits = typename __iter_traits_impl<_Iter, _Tp>::type; 207 208 template<typename _Tp> 209 using __iter_diff_t = typename 210 __iter_traits<_Tp, incrementable_traits<_Tp>>::difference_type; 211 } // namespace __detail 212 213 template<typename _Tp> 214 using iter_difference_t = __detail::__iter_diff_t<remove_cvref_t<_Tp>>; 215 216 namespace __detail 217 { 218 template<typename> struct __cond_value_type { }; 219 220 template<typename _Tp> requires is_object_v<_Tp> 221 struct __cond_value_type<_Tp> 222 { using value_type = remove_cv_t<_Tp>; }; 223 } // namespace __detail 224 225 template<typename> struct indirectly_readable_traits { }; 226 227 template<typename _Tp> 228 struct indirectly_readable_traits<_Tp*> 229 : __detail::__cond_value_type<_Tp> 230 { }; 231 232 template<typename _Iter> requires is_array_v<_Iter> 233 struct indirectly_readable_traits<_Iter> 234 { using value_type = remove_cv_t<remove_extent_t<_Iter>>; }; 235 236 template<typename _Iter> 237 struct indirectly_readable_traits<const _Iter> 238 : indirectly_readable_traits<_Iter> 239 { }; 240 241 template<typename _Tp> requires requires { typename _Tp::value_type; } 242 struct indirectly_readable_traits<_Tp> 243 : __detail::__cond_value_type<typename _Tp::value_type> 244 { }; 245 246 template<typename _Tp> requires requires { typename _Tp::element_type; } 247 struct indirectly_readable_traits<_Tp> 248 : __detail::__cond_value_type<typename _Tp::element_type> 249 { }; 250 251 namespace __detail 252 { 253 template<typename _Tp> 254 using __iter_value_t = typename 255 __iter_traits<_Tp, indirectly_readable_traits<_Tp>>::value_type; 256 } // namespace __detail 257 258 template<typename _Tp> 259 using iter_value_t = __detail::__iter_value_t<remove_cvref_t<_Tp>>; 260 261 namespace __detail 262 { 263 // _GLIBCXX_RESOLVE_LIB_DEFECTS 264 // 3420. cpp17-iterator should check [type] looks like an iterator first 265 template<typename _Iter> 266 concept __cpp17_iterator = requires(_Iter __it) 267 { 268 { *__it } -> __can_reference; 269 { ++__it } -> same_as<_Iter&>; 270 { *__it++ } -> __can_reference; 271 } && copyable<_Iter>; 272 273 template<typename _Iter> 274 concept __cpp17_input_iterator = __cpp17_iterator<_Iter> 275 && equality_comparable<_Iter> 276 && requires(_Iter __it) 277 { 278 typename incrementable_traits<_Iter>::difference_type; 279 typename indirectly_readable_traits<_Iter>::value_type; 280 typename common_reference_t<iter_reference_t<_Iter>&&, 281 typename indirectly_readable_traits<_Iter>::value_type&>; 282 typename common_reference_t<decltype(*__it++)&&, 283 typename indirectly_readable_traits<_Iter>::value_type&>; 284 requires signed_integral< 285 typename incrementable_traits<_Iter>::difference_type>; 286 }; 287 288 template<typename _Iter> 289 concept __cpp17_fwd_iterator = __cpp17_input_iterator<_Iter> 290 && constructible_from<_Iter> 291 && is_lvalue_reference_v<iter_reference_t<_Iter>> 292 && same_as<remove_cvref_t<iter_reference_t<_Iter>>, 293 typename indirectly_readable_traits<_Iter>::value_type> 294 && requires(_Iter __it) 295 { 296 { __it++ } -> convertible_to<const _Iter&>; 297 { *__it++ } -> same_as<iter_reference_t<_Iter>>; 298 }; 299 300 template<typename _Iter> 301 concept __cpp17_bidi_iterator = __cpp17_fwd_iterator<_Iter> 302 && requires(_Iter __it) 303 { 304 { --__it } -> same_as<_Iter&>; 305 { __it-- } -> convertible_to<const _Iter&>; 306 { *__it-- } -> same_as<iter_reference_t<_Iter>>; 307 }; 308 309 template<typename _Iter> 310 concept __cpp17_randacc_iterator = __cpp17_bidi_iterator<_Iter> 311 && totally_ordered<_Iter> 312 && requires(_Iter __it, 313 typename incrementable_traits<_Iter>::difference_type __n) 314 { 315 { __it += __n } -> same_as<_Iter&>; 316 { __it -= __n } -> same_as<_Iter&>; 317 { __it + __n } -> same_as<_Iter>; 318 { __n + __it } -> same_as<_Iter>; 319 { __it - __n } -> same_as<_Iter>; 320 { __it - __it } -> same_as<decltype(__n)>; 321 { __it[__n] } -> convertible_to<iter_reference_t<_Iter>>; 322 }; 323 324 template<typename _Iter> 325 concept __iter_with_nested_types = requires { 326 typename _Iter::iterator_category; 327 typename _Iter::value_type; 328 typename _Iter::difference_type; 329 typename _Iter::reference; 330 }; 331 332 template<typename _Iter> 333 concept __iter_without_nested_types = !__iter_with_nested_types<_Iter>; 334 335 template<typename _Iter> 336 concept __iter_without_category 337 = !requires { typename _Iter::iterator_category; }; 338 339 } // namespace __detail 340 341 template<typename _Iterator> 342 requires __detail::__iter_with_nested_types<_Iterator> 343 struct __iterator_traits<_Iterator, void> 344 { 345 private: 346 template<typename _Iter> 347 struct __ptr 348 { using type = void; }; 349 350 template<typename _Iter> requires requires { typename _Iter::pointer; } 351 struct __ptr<_Iter> 352 { using type = typename _Iter::pointer; }; 353 354 public: 355 using iterator_category = typename _Iterator::iterator_category; 356 using value_type = typename _Iterator::value_type; 357 using difference_type = typename _Iterator::difference_type; 358 using pointer = typename __ptr<_Iterator>::type; 359 using reference = typename _Iterator::reference; 360 }; 361 362 template<typename _Iterator> 363 requires __detail::__iter_without_nested_types<_Iterator> 364 && __detail::__cpp17_input_iterator<_Iterator> 365 struct __iterator_traits<_Iterator, void> 366 { 367 private: 368 template<typename _Iter> 369 struct __cat 370 { using type = input_iterator_tag; }; 371 372 template<typename _Iter> 373 requires requires { typename _Iter::iterator_category; } 374 struct __cat<_Iter> 375 { using type = typename _Iter::iterator_category; }; 376 377 template<typename _Iter> 378 requires __detail::__iter_without_category<_Iter> 379 && __detail::__cpp17_randacc_iterator<_Iter> 380 struct __cat<_Iter> 381 { using type = random_access_iterator_tag; }; 382 383 template<typename _Iter> 384 requires __detail::__iter_without_category<_Iter> 385 && __detail::__cpp17_bidi_iterator<_Iter> 386 struct __cat<_Iter> 387 { using type = bidirectional_iterator_tag; }; 388 389 template<typename _Iter> 390 requires __detail::__iter_without_category<_Iter> 391 && __detail::__cpp17_fwd_iterator<_Iter> 392 struct __cat<_Iter> 393 { using type = forward_iterator_tag; }; 394 395 template<typename _Iter> 396 struct __ptr 397 { using type = void; }; 398 399 template<typename _Iter> requires requires { typename _Iter::pointer; } 400 struct __ptr<_Iter> 401 { using type = typename _Iter::pointer; }; 402 403 template<typename _Iter> 404 requires (!requires { typename _Iter::pointer; } 405 && requires(_Iter& __it) { __it.operator->(); }) 406 struct __ptr<_Iter> 407 { using type = decltype(std::declval<_Iter&>().operator->()); }; 408 409 template<typename _Iter> 410 struct __ref 411 { using type = iter_reference_t<_Iter>; }; 412 413 template<typename _Iter> requires requires { typename _Iter::reference; } 414 struct __ref<_Iter> 415 { using type = typename _Iter::reference; }; 416 417 public: 418 using iterator_category = typename __cat<_Iterator>::type; 419 using value_type 420 = typename indirectly_readable_traits<_Iterator>::value_type; 421 using difference_type 422 = typename incrementable_traits<_Iterator>::difference_type; 423 using pointer = typename __ptr<_Iterator>::type; 424 using reference = typename __ref<_Iterator>::type; 425 }; 426 427 template<typename _Iterator> 428 requires __detail::__iter_without_nested_types<_Iterator> 429 && __detail::__cpp17_iterator<_Iterator> 430 struct __iterator_traits<_Iterator, void> 431 { 432 private: 433 template<typename _Iter> 434 struct __diff 435 { using type = void; }; 436 437 template<typename _Iter> 438 requires requires 439 { typename incrementable_traits<_Iter>::difference_type; } 440 struct __diff<_Iter> 441 { 442 using type = typename incrementable_traits<_Iter>::difference_type; 443 }; 444 445 public: 446 using iterator_category = output_iterator_tag; 447 using value_type = void; 448 using difference_type = typename __diff<_Iterator>::type; 449 using pointer = void; 450 using reference = void; 451 }; 452 453 namespace __detail 454 { 455 template<typename _Iter> 456 struct __iter_concept_impl; 457 458 // ITER_CONCEPT(I) is ITER_TRAITS(I)::iterator_concept if that is valid. 459 template<typename _Iter> 460 requires requires { typename __iter_traits<_Iter>::iterator_concept; } 461 struct __iter_concept_impl<_Iter> 462 { using type = typename __iter_traits<_Iter>::iterator_concept; }; 463 464 // Otherwise, ITER_TRAITS(I)::iterator_category if that is valid. 465 template<typename _Iter> 466 requires (!requires { typename __iter_traits<_Iter>::iterator_concept; } 467 && requires { typename __iter_traits<_Iter>::iterator_category; }) 468 struct __iter_concept_impl<_Iter> 469 { using type = typename __iter_traits<_Iter>::iterator_category; }; 470 471 // Otherwise, random_access_tag if iterator_traits<I> is not specialized. 472 template<typename _Iter> 473 requires (!requires { typename __iter_traits<_Iter>::iterator_concept; } 474 && !requires { typename __iter_traits<_Iter>::iterator_category; } 475 && __primary_traits_iter<_Iter>) 476 struct __iter_concept_impl<_Iter> 477 { using type = random_access_iterator_tag; }; 478 479 // Otherwise, there is no ITER_CONCEPT(I) type. 480 template<typename _Iter> 481 struct __iter_concept_impl 482 { }; 483 484 // ITER_CONCEPT 485 template<typename _Iter> 486 using __iter_concept = typename __iter_concept_impl<_Iter>::type; 487 488 template<typename _In> 489 concept __indirectly_readable_impl = requires(const _In __in) 490 { 491 typename iter_value_t<_In>; 492 typename iter_reference_t<_In>; 493 typename iter_rvalue_reference_t<_In>; 494 { *__in } -> same_as<iter_reference_t<_In>>; 495 { ranges::iter_move(__in) } -> same_as<iter_rvalue_reference_t<_In>>; 496 } 497 && common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> 498 && common_reference_with<iter_reference_t<_In>&&, 499 iter_rvalue_reference_t<_In>&&> 500 && common_reference_with<iter_rvalue_reference_t<_In>&&, 501 const iter_value_t<_In>&>; 502 503 } // namespace __detail 504 505 /// Requirements for types that are readable by applying operator*. 506 template<typename _In> 507 concept indirectly_readable 508 = __detail::__indirectly_readable_impl<remove_cvref_t<_In>>; 509 510 template<indirectly_readable _Tp> 511 using iter_common_reference_t 512 = common_reference_t<iter_reference_t<_Tp>, iter_value_t<_Tp>&>; 513 514 /// Requirements for writing a value into an iterator's referenced object. 515 template<typename _Out, typename _Tp> 516 concept indirectly_writable = requires(_Out&& __o, _Tp&& __t) 517 { 518 *__o = std::forward<_Tp>(__t); 519 *std::forward<_Out>(__o) = std::forward<_Tp>(__t); 520 const_cast<const iter_reference_t<_Out>&&>(*__o) 521 = std::forward<_Tp>(__t); 522 const_cast<const iter_reference_t<_Out>&&>(*std::forward<_Out>(__o)) 523 = std::forward<_Tp>(__t); 524 }; 525 526 namespace ranges::__detail 527 { 528 #if __SIZEOF_INT128__ 529 using __max_diff_type = __int128; 530 using __max_size_type = unsigned __int128; 531 #else 532 using __max_diff_type = long long; 533 using __max_size_type = unsigned long long; 534 #endif 535 536 template<typename _Tp> 537 concept __is_integer_like = integral<_Tp> 538 || same_as<_Tp, __max_diff_type> || same_as<_Tp, __max_size_type>; 539 540 template<typename _Tp> 541 concept __is_signed_integer_like = signed_integral<_Tp> 542 || same_as<_Tp, __max_diff_type>; 543 544 } // namespace ranges::__detail 545 546 namespace __detail { using ranges::__detail::__is_signed_integer_like; } 547 548 /// Requirements on types that can be incremented with ++. 549 template<typename _Iter> 550 concept weakly_incrementable = default_initializable<_Iter> 551 && movable<_Iter> 552 && requires(_Iter __i) 553 { 554 typename iter_difference_t<_Iter>; 555 requires __detail::__is_signed_integer_like<iter_difference_t<_Iter>>; 556 { ++__i } -> same_as<_Iter&>; 557 __i++; 558 }; 559 560 template<typename _Iter> 561 concept incrementable = regular<_Iter> && weakly_incrementable<_Iter> 562 && requires(_Iter __i) { { __i++ } -> same_as<_Iter>; }; 563 564 template<typename _Iter> 565 concept input_or_output_iterator 566 = requires(_Iter __i) { { *__i } -> __detail::__can_reference; } 567 && weakly_incrementable<_Iter>; 568 569 template<typename _Sent, typename _Iter> 570 concept sentinel_for = semiregular<_Sent> 571 && input_or_output_iterator<_Iter> 572 && __detail::__weakly_eq_cmp_with<_Sent, _Iter>; 573 574 template<typename _Sent, typename _Iter> 575 inline constexpr bool disable_sized_sentinel_for = false; 576 577 template<typename _Sent, typename _Iter> 578 concept sized_sentinel_for = sentinel_for<_Sent, _Iter> 579 && !disable_sized_sentinel_for<remove_cv_t<_Sent>, remove_cv_t<_Iter>> 580 && requires(const _Iter& __i, const _Sent& __s) 581 { 582 { __s - __i } -> same_as<iter_difference_t<_Iter>>; 583 { __i - __s } -> same_as<iter_difference_t<_Iter>>; 584 }; 585 586 template<typename _Iter> 587 concept input_iterator = input_or_output_iterator<_Iter> 588 && indirectly_readable<_Iter> 589 && requires { typename __detail::__iter_concept<_Iter>; } 590 && derived_from<__detail::__iter_concept<_Iter>, input_iterator_tag>; 591 592 template<typename _Iter, typename _Tp> 593 concept output_iterator = input_or_output_iterator<_Iter> 594 && indirectly_writable<_Iter, _Tp> 595 && requires(_Iter __i, _Tp&& __t) { *__i++ = std::forward<_Tp>(__t); }; 596 597 template<typename _Iter> 598 concept forward_iterator = input_iterator<_Iter> 599 && derived_from<__detail::__iter_concept<_Iter>, forward_iterator_tag> 600 && incrementable<_Iter> && sentinel_for<_Iter, _Iter>; 601 602 template<typename _Iter> 603 concept bidirectional_iterator = forward_iterator<_Iter> 604 && derived_from<__detail::__iter_concept<_Iter>, 605 bidirectional_iterator_tag> 606 && requires(_Iter __i) 607 { 608 { --__i } -> same_as<_Iter&>; 609 { __i-- } -> same_as<_Iter>; 610 }; 611 612 template<typename _Iter> 613 concept random_access_iterator = bidirectional_iterator<_Iter> 614 && derived_from<__detail::__iter_concept<_Iter>, 615 random_access_iterator_tag> 616 && totally_ordered<_Iter> && sized_sentinel_for<_Iter, _Iter> 617 && requires(_Iter __i, const _Iter __j, 618 const iter_difference_t<_Iter> __n) 619 { 620 { __i += __n } -> same_as<_Iter&>; 621 { __j + __n } -> same_as<_Iter>; 622 { __n + __j } -> same_as<_Iter>; 623 { __i -= __n } -> same_as<_Iter&>; 624 { __j - __n } -> same_as<_Iter>; 625 { __j[__n] } -> same_as<iter_reference_t<_Iter>>; 626 }; 627 628 template<typename _Iter> 629 concept contiguous_iterator = random_access_iterator<_Iter> 630 && derived_from<__detail::__iter_concept<_Iter>, contiguous_iterator_tag> 631 && is_lvalue_reference_v<iter_reference_t<_Iter>> 632 && same_as<iter_value_t<_Iter>, remove_cvref_t<iter_reference_t<_Iter>>> 633 && requires(const _Iter& __i) 634 { 635 { std::to_address(__i) } 636 -> same_as<add_pointer_t<iter_reference_t<_Iter>>>; 637 }; 638 639 // [indirectcallable], indirect callable requirements 640 641 // [indirectcallable.indirectinvocable], indirect callables 642 643 template<typename _Fn, typename _Iter> 644 concept indirectly_unary_invocable = indirectly_readable<_Iter> 645 && copy_constructible<_Fn> && invocable<_Fn&, iter_value_t<_Iter>&> 646 && invocable<_Fn&, iter_reference_t<_Iter>> 647 && invocable<_Fn&, iter_common_reference_t<_Iter>> 648 && common_reference_with<invoke_result_t<_Fn&, iter_value_t<_Iter>&>, 649 invoke_result_t<_Fn&, iter_reference_t<_Iter>>>; 650 651 template<typename _Fn, typename _Iter> 652 concept indirectly_regular_unary_invocable = indirectly_readable<_Iter> 653 && copy_constructible<_Fn> 654 && regular_invocable<_Fn&, iter_value_t<_Iter>&> 655 && regular_invocable<_Fn&, iter_reference_t<_Iter>> 656 && regular_invocable<_Fn&, iter_common_reference_t<_Iter>> 657 && common_reference_with<invoke_result_t<_Fn&, iter_value_t<_Iter>&>, 658 invoke_result_t<_Fn&, iter_reference_t<_Iter>>>; 659 660 template<typename _Fn, typename _Iter> 661 concept indirect_unary_predicate = indirectly_readable<_Iter> 662 && copy_constructible<_Fn> && predicate<_Fn&, iter_value_t<_Iter>&> 663 && predicate<_Fn&, iter_reference_t<_Iter>> 664 && predicate<_Fn&, iter_common_reference_t<_Iter>>; 665 666 template<typename _Fn, typename _I1, typename _I2> 667 concept indirect_binary_predicate 668 = indirectly_readable<_I1> && indirectly_readable<_I2> 669 && copy_constructible<_Fn> 670 && predicate<_Fn&, iter_value_t<_I1>&, iter_value_t<_I2>&> 671 && predicate<_Fn&, iter_value_t<_I1>&, iter_reference_t<_I2>> 672 && predicate<_Fn&, iter_reference_t<_I1>, iter_value_t<_I2>&> 673 && predicate<_Fn&, iter_reference_t<_I1>, iter_reference_t<_I2>> 674 && predicate<_Fn&, iter_common_reference_t<_I1>, 675 iter_common_reference_t<_I2>>; 676 677 template<typename _Fn, typename _I1, typename _I2 = _I1> 678 concept indirect_equivalence_relation 679 = indirectly_readable<_I1> && indirectly_readable<_I2> 680 && copy_constructible<_Fn> 681 && equivalence_relation<_Fn&, iter_value_t<_I1>&, iter_value_t<_I2>&> 682 && equivalence_relation<_Fn&, iter_value_t<_I1>&, iter_reference_t<_I2>> 683 && equivalence_relation<_Fn&, iter_reference_t<_I1>, iter_value_t<_I2>&> 684 && equivalence_relation<_Fn&, iter_reference_t<_I1>, 685 iter_reference_t<_I2>> 686 && equivalence_relation<_Fn&, iter_common_reference_t<_I1>, 687 iter_common_reference_t<_I2>>; 688 689 template<typename _Fn, typename _I1, typename _I2 = _I1> 690 concept indirect_strict_weak_order 691 = indirectly_readable<_I1> && indirectly_readable<_I2> 692 && copy_constructible<_Fn> 693 && strict_weak_order<_Fn&, iter_value_t<_I1>&, iter_value_t<_I2>&> 694 && strict_weak_order<_Fn&, iter_value_t<_I1>&, iter_reference_t<_I2>> 695 && strict_weak_order<_Fn&, iter_reference_t<_I1>, iter_value_t<_I2>&> 696 && strict_weak_order<_Fn&, iter_reference_t<_I1>, iter_reference_t<_I2>> 697 && strict_weak_order<_Fn&, iter_common_reference_t<_I1>, 698 iter_common_reference_t<_I2>>; 699 700 template<typename _Fn, typename... _Is> 701 requires (indirectly_readable<_Is> && ...) 702 && invocable<_Fn, iter_reference_t<_Is>...> 703 using indirect_result_t = invoke_result_t<_Fn, iter_reference_t<_Is>...>; 704 705 /// [projected], projected 706 template<indirectly_readable _Iter, 707 indirectly_regular_unary_invocable<_Iter> _Proj> 708 struct projected 709 { 710 using value_type = remove_cvref_t<indirect_result_t<_Proj&, _Iter>>; 711 712 indirect_result_t<_Proj&, _Iter> operator*() const; // not defined 713 }; 714 715 template<weakly_incrementable _Iter, typename _Proj> 716 struct incrementable_traits<projected<_Iter, _Proj>> 717 { using difference_type = iter_difference_t<_Iter>; }; 718 719 // [alg.req], common algorithm requirements 720 721 /// [alg.req.ind.move], concept `indirectly_movable` 722 723 template<typename _In, typename _Out> 724 concept indirectly_movable = indirectly_readable<_In> 725 && indirectly_writable<_Out, iter_rvalue_reference_t<_In>>; 726 727 template<typename _In, typename _Out> 728 concept indirectly_movable_storable = indirectly_movable<_In, _Out> 729 && indirectly_writable<_Out, iter_value_t<_In>> 730 && movable<iter_value_t<_In>> 731 && constructible_from<iter_value_t<_In>, iter_rvalue_reference_t<_In>> 732 && assignable_from<iter_value_t<_In>&, iter_rvalue_reference_t<_In>>; 733 734 /// [alg.req.ind.copy], concept `indirectly_copyable` 735 template<typename _In, typename _Out> 736 concept indirectly_copyable = indirectly_readable<_In> 737 && indirectly_writable<_Out, iter_reference_t<_In>>; 738 739 template<typename _In, typename _Out> 740 concept indirectly_copyable_storable = indirectly_copyable<_In, _Out> 741 && indirectly_writable<_Out, iter_value_t<_In>&> 742 && indirectly_writable<_Out, const iter_value_t<_In>&> 743 && indirectly_writable<_Out, iter_value_t<_In>&&> 744 && indirectly_writable<_Out, const iter_value_t<_In>&&> 745 && copyable<iter_value_t<_In>> 746 && constructible_from<iter_value_t<_In>, iter_reference_t<_In>> 747 && assignable_from<iter_value_t<_In>&, iter_reference_t<_In>>; 748 749 namespace ranges 750 { 751 namespace __cust_iswap 752 { 753 template<typename _It1, typename _It2> 754 void iter_swap(_It1, _It2) = delete; 755 756 template<typename _Tp, typename _Up> 757 concept __adl_iswap 758 = (std::__detail::__class_or_enum<remove_reference_t<_Tp>> 759 || std::__detail::__class_or_enum<remove_reference_t<_Up>>) 760 && requires(_Tp&& __t, _Up&& __u) { 761 iter_swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u)); 762 }; 763 764 template<typename _Xp, typename _Yp> 765 constexpr iter_value_t<_Xp> 766 __iter_exchange_move(_Xp&& __x, _Yp&& __y) 767 noexcept(noexcept(iter_value_t<_Xp>(iter_move(__x))) 768 && noexcept(*__x = iter_move(__y))) 769 { 770 iter_value_t<_Xp> __old_value(iter_move(__x)); 771 *__x = iter_move(__y); 772 return __old_value; 773 } 774 775 struct _IterSwap 776 { 777 private: 778 template<typename _Tp, typename _Up> 779 static constexpr bool 780 _S_noexcept() 781 { 782 if constexpr (__adl_iswap<_Tp, _Up>) 783 return noexcept(iter_swap(std::declval<_Tp>(), 784 std::declval<_Up>())); 785 else if constexpr (indirectly_readable<_Tp> 786 && indirectly_readable<_Up> 787 && swappable_with<iter_reference_t<_Tp>, iter_reference_t<_Up>>) 788 return noexcept(ranges::swap(*std::declval<_Tp>(), 789 *std::declval<_Up>())); 790 else 791 return noexcept(*std::declval<_Tp>() 792 = __iter_exchange_move(std::declval<_Up>(), 793 std::declval<_Tp>())); 794 } 795 796 public: 797 template<typename _Tp, typename _Up> 798 requires __adl_iswap<_Tp, _Up> 799 || (indirectly_readable<remove_reference_t<_Tp>> 800 && indirectly_readable<remove_reference_t<_Up>> 801 && swappable_with<iter_reference_t<_Tp>, iter_reference_t<_Up>>) 802 || (indirectly_movable_storable<_Tp, _Up> 803 && indirectly_movable_storable<_Up, _Tp>) 804 constexpr void 805 operator()(_Tp&& __e1, _Up&& __e2) const 806 noexcept(_S_noexcept<_Tp, _Up>()) 807 { 808 if constexpr (__adl_iswap<_Tp, _Up>) 809 iter_swap(static_cast<_Tp&&>(__e1), static_cast<_Up&&>(__e2)); 810 else if constexpr (indirectly_readable<_Tp> 811 && indirectly_readable<_Up> 812 && swappable_with<iter_reference_t<_Tp>, iter_reference_t<_Up>>) 813 ranges::swap(*__e1, *__e2); 814 else 815 *__e1 = __iter_exchange_move(__e2, __e1); 816 } 817 }; 818 } // namespace __cust_iswap 819 820 inline namespace __cust 821 { 822 inline constexpr __cust_iswap::_IterSwap iter_swap{}; 823 } // inline namespace __cust 824 825 } // namespace ranges 826 827 /// [alg.req.ind.swap], concept `indirectly_swappable` 828 template<typename _I1, typename _I2 = _I1> 829 concept indirectly_swappable 830 = indirectly_readable<_I1> && indirectly_readable<_I2> 831 && requires(const _I1 __i1, const _I2 __i2) 832 { 833 ranges::iter_swap(__i1, __i1); 834 ranges::iter_swap(__i2, __i2); 835 ranges::iter_swap(__i1, __i2); 836 ranges::iter_swap(__i2, __i1); 837 }; 838 839 /// [alg.req.ind.cmp], concept `indirectly_comparable` 840 template<typename _I1, typename _I2, typename _Rel, typename _P1 = identity, 841 typename _P2 = identity> 842 concept indirectly_comparable 843 = indirect_binary_predicate<_Rel, projected<_I1, _P1>, 844 projected<_I2, _P2>>; 845 846 /// [alg.req.permutable], concept `permutable` 847 template<typename _Iter> 848 concept permutable = forward_iterator<_Iter> 849 && indirectly_movable_storable<_Iter, _Iter> 850 && indirectly_swappable<_Iter, _Iter>; 851 852 /// [alg.req.mergeable], concept `mergeable` 853 template<typename _I1, typename _I2, typename _Out, 854 typename _Rel = ranges::less, typename _P1 = identity, 855 typename _P2 = identity> 856 concept mergeable = input_iterator<_I1> && input_iterator<_I2> 857 && weakly_incrementable<_Out> && indirectly_copyable<_I1, _Out> 858 && indirectly_copyable<_I2, _Out> 859 && indirect_strict_weak_order<_Rel, projected<_I1, _P1>, 860 projected<_I2, _P2>>; 861 862 /// [alg.req.sortable], concept `sortable` 863 template<typename _Iter, typename _Rel = ranges::less, 864 typename _Proj = identity> 865 concept sortable = permutable<_Iter> 866 && indirect_strict_weak_order<_Rel, projected<_Iter, _Proj>>; 867 868 struct unreachable_sentinel_t 869 { 870 template<weakly_incrementable _It> 871 friend constexpr bool 872 operator==(unreachable_sentinel_t, const _It&) noexcept 873 { return false; } 874 }; 875 876 inline constexpr unreachable_sentinel_t unreachable_sentinel{}; 877 878 struct default_sentinel_t { }; 879 inline constexpr default_sentinel_t default_sentinel{}; 880 881 namespace __detail 882 { 883 template<typename _Tp> 884 constexpr decay_t<_Tp> 885 __decay_copy(_Tp&& __t) 886 noexcept(is_nothrow_convertible_v<_Tp, decay_t<_Tp>>) 887 { return std::forward<_Tp>(__t); } 888 889 template<typename _Tp> 890 concept __member_begin = requires(_Tp& __t) 891 { 892 { __detail::__decay_copy(__t.begin()) } -> input_or_output_iterator; 893 }; 894 895 void begin(auto&) = delete; 896 void begin(const auto&) = delete; 897 898 template<typename _Tp> 899 concept __adl_begin = __class_or_enum<remove_reference_t<_Tp>> 900 && requires(_Tp& __t) 901 { 902 { __detail::__decay_copy(begin(__t)) } -> input_or_output_iterator; 903 }; 904 905 // Simplified version of std::ranges::begin that only supports lvalues, 906 // for use by __range_iter_t below. 907 template<typename _Tp> 908 requires is_array_v<_Tp> || __member_begin<_Tp&> || __adl_begin<_Tp&> 909 auto 910 __ranges_begin(_Tp& __t) 911 { 912 if constexpr (is_array_v<_Tp>) 913 { 914 static_assert(sizeof(remove_all_extents_t<_Tp>) != 0, 915 "not array of incomplete type"); 916 return __t + 0; 917 } 918 else if constexpr (__member_begin<_Tp&>) 919 return __t.begin(); 920 else 921 return begin(__t); 922 } 923 924 // Implementation of std::ranges::iterator_t, without using ranges::begin. 925 template<typename _Tp> 926 using __range_iter_t 927 = decltype(__detail::__ranges_begin(std::declval<_Tp&>())); 928 929 } // namespace __detail 930 931 _GLIBCXX_END_NAMESPACE_VERSION 932 } // namespace std 933 #endif // C++20 library concepts 934 #endif // _ITERATOR_CONCEPTS_H 935