1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP_VARIANT 11#define _LIBCPP_VARIANT 12 13/* 14 variant synopsis 15 16namespace std { 17 18 // 20.7.2, class template variant 19 template <class... Types> 20 class variant { 21 public: 22 23 // 20.7.2.1, constructors 24 constexpr variant() noexcept(see below); 25 constexpr variant(const variant&); 26 constexpr variant(variant&&) noexcept(see below); 27 28 template <class T> constexpr variant(T&&) noexcept(see below); 29 30 template <class T, class... Args> 31 constexpr explicit variant(in_place_type_t<T>, Args&&...); 32 33 template <class T, class U, class... Args> 34 constexpr explicit variant( 35 in_place_type_t<T>, initializer_list<U>, Args&&...); 36 37 template <size_t I, class... Args> 38 constexpr explicit variant(in_place_index_t<I>, Args&&...); 39 40 template <size_t I, class U, class... Args> 41 constexpr explicit variant( 42 in_place_index_t<I>, initializer_list<U>, Args&&...); 43 44 // 20.7.2.2, destructor 45 ~variant(); 46 47 // 20.7.2.3, assignment 48 constexpr variant& operator=(const variant&); 49 constexpr variant& operator=(variant&&) noexcept(see below); 50 51 template <class T> variant& operator=(T&&) noexcept(see below); 52 53 // 20.7.2.4, modifiers 54 template <class T, class... Args> 55 T& emplace(Args&&...); 56 57 template <class T, class U, class... Args> 58 T& emplace(initializer_list<U>, Args&&...); 59 60 template <size_t I, class... Args> 61 variant_alternative_t<I, variant>& emplace(Args&&...); 62 63 template <size_t I, class U, class... Args> 64 variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...); 65 66 // 20.7.2.5, value status 67 constexpr bool valueless_by_exception() const noexcept; 68 constexpr size_t index() const noexcept; 69 70 // 20.7.2.6, swap 71 void swap(variant&) noexcept(see below); 72 }; 73 74 // 20.7.3, variant helper classes 75 template <class T> struct variant_size; // undefined 76 77 template <class T> 78 inline constexpr size_t variant_size_v = variant_size<T>::value; 79 80 template <class T> struct variant_size<const T>; 81 template <class T> struct variant_size<volatile T>; 82 template <class T> struct variant_size<const volatile T>; 83 84 template <class... Types> 85 struct variant_size<variant<Types...>>; 86 87 template <size_t I, class T> struct variant_alternative; // undefined 88 89 template <size_t I, class T> 90 using variant_alternative_t = typename variant_alternative<I, T>::type; 91 92 template <size_t I, class T> struct variant_alternative<I, const T>; 93 template <size_t I, class T> struct variant_alternative<I, volatile T>; 94 template <size_t I, class T> struct variant_alternative<I, const volatile T>; 95 96 template <size_t I, class... Types> 97 struct variant_alternative<I, variant<Types...>>; 98 99 inline constexpr size_t variant_npos = -1; 100 101 // 20.7.4, value access 102 template <class T, class... Types> 103 constexpr bool holds_alternative(const variant<Types...>&) noexcept; 104 105 template <size_t I, class... Types> 106 constexpr variant_alternative_t<I, variant<Types...>>& 107 get(variant<Types...>&); 108 109 template <size_t I, class... Types> 110 constexpr variant_alternative_t<I, variant<Types...>>&& 111 get(variant<Types...>&&); 112 113 template <size_t I, class... Types> 114 constexpr variant_alternative_t<I, variant<Types...>> const& 115 get(const variant<Types...>&); 116 117 template <size_t I, class... Types> 118 constexpr variant_alternative_t<I, variant<Types...>> const&& 119 get(const variant<Types...>&&); 120 121 template <class T, class... Types> 122 constexpr T& get(variant<Types...>&); 123 124 template <class T, class... Types> 125 constexpr T&& get(variant<Types...>&&); 126 127 template <class T, class... Types> 128 constexpr const T& get(const variant<Types...>&); 129 130 template <class T, class... Types> 131 constexpr const T&& get(const variant<Types...>&&); 132 133 template <size_t I, class... Types> 134 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>> 135 get_if(variant<Types...>*) noexcept; 136 137 template <size_t I, class... Types> 138 constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>> 139 get_if(const variant<Types...>*) noexcept; 140 141 template <class T, class... Types> 142 constexpr add_pointer_t<T> 143 get_if(variant<Types...>*) noexcept; 144 145 template <class T, class... Types> 146 constexpr add_pointer_t<const T> 147 get_if(const variant<Types...>*) noexcept; 148 149 // 20.7.5, relational operators 150 template <class... Types> 151 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&); 152 153 template <class... Types> 154 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&); 155 156 template <class... Types> 157 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&); 158 159 template <class... Types> 160 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&); 161 162 template <class... Types> 163 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&); 164 165 template <class... Types> 166 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&); 167 168 template <class... Types> requires (three_way_comparable<Types> && ...) 169 constexpr common_comparison_category_t<compare_three_way_result_t<Types>...> 170 operator<=>(const variant<Types...>&, const variant<Types...>&); // since C++20 171 172 // 20.7.6, visitation 173 template <class Visitor, class... Variants> 174 constexpr see below visit(Visitor&&, Variants&&...); 175 176 template <class R, class Visitor, class... Variants> 177 constexpr R visit(Visitor&&, Variants&&...); // since C++20 178 179 // 20.7.7, class monostate 180 struct monostate; 181 182 // 20.7.8, monostate relational operators 183 constexpr bool operator==(monostate, monostate) noexcept; 184 constexpr bool operator!=(monostate, monostate) noexcept; // until C++20 185 constexpr bool operator<(monostate, monostate) noexcept; // until C++20 186 constexpr bool operator>(monostate, monostate) noexcept; // until C++20 187 constexpr bool operator<=(monostate, monostate) noexcept; // until C++20 188 constexpr bool operator>=(monostate, monostate) noexcept; // until C++20 189 constexpr strong_ordering operator<=>(monostate, monostate) noexcept; // since C++20 190 191 // 20.7.9, specialized algorithms 192 template <class... Types> 193 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below); 194 195 // 20.7.10, class bad_variant_access 196 class bad_variant_access; 197 198 // 20.7.11, hash support 199 template <class T> struct hash; 200 template <class... Types> struct hash<variant<Types...>>; 201 template <> struct hash<monostate>; 202 203} // namespace std 204 205*/ 206 207#include <__assert> // all public C++ headers provide the assertion handler 208#include <__availability> 209#include <__compare/common_comparison_category.h> 210#include <__compare/compare_three_way_result.h> 211#include <__compare/three_way_comparable.h> 212#include <__config> 213#include <__exception/exception.h> 214#include <__functional/hash.h> 215#include <__functional/invoke.h> 216#include <__functional/operations.h> 217#include <__functional/unary_function.h> 218#include <__memory/addressof.h> 219#include <__type_traits/add_const.h> 220#include <__type_traits/add_cv.h> 221#include <__type_traits/add_pointer.h> 222#include <__type_traits/add_volatile.h> 223#include <__type_traits/dependent_type.h> 224#include <__type_traits/is_array.h> 225#include <__type_traits/is_destructible.h> 226#include <__type_traits/is_nothrow_move_constructible.h> 227#include <__type_traits/is_trivially_copy_assignable.h> 228#include <__type_traits/is_trivially_copy_constructible.h> 229#include <__type_traits/is_trivially_destructible.h> 230#include <__type_traits/is_trivially_move_assignable.h> 231#include <__type_traits/is_trivially_move_constructible.h> 232#include <__type_traits/is_void.h> 233#include <__type_traits/remove_const.h> 234#include <__type_traits/type_identity.h> 235#include <__type_traits/void_t.h> 236#include <__utility/declval.h> 237#include <__utility/forward.h> 238#include <__utility/in_place.h> 239#include <__utility/move.h> 240#include <__utility/swap.h> 241#include <__variant/monostate.h> 242#include <__verbose_abort> 243#include <initializer_list> 244#include <limits> 245#include <new> 246#include <tuple> 247#include <version> 248 249// standard-mandated includes 250 251// [variant.syn] 252#include <compare> 253 254#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 255# pragma GCC system_header 256#endif 257 258_LIBCPP_PUSH_MACROS 259#include <__undef_macros> 260 261namespace std { // explicitly not using versioning namespace 262 263class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception { 264public: 265 const char* what() const _NOEXCEPT override; 266}; 267 268} // namespace std 269 270_LIBCPP_BEGIN_NAMESPACE_STD 271 272#if _LIBCPP_STD_VER >= 17 273 274// Light N-dimensional array of function pointers. Used in place of std::array to avoid 275// adding a dependency. 276template<class _Tp, size_t _Size> 277struct __farray { 278 static_assert(_Size > 0, "N-dimensional array should never be empty in std::visit"); 279 _Tp __buf_[_Size] = {}; 280 281 _LIBCPP_HIDE_FROM_ABI constexpr 282 const _Tp &operator[](size_t __n) const noexcept { 283 return __buf_[__n]; 284 } 285}; 286 287_LIBCPP_NORETURN 288inline _LIBCPP_HIDE_FROM_ABI 289_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 290void __throw_bad_variant_access() { 291#ifndef _LIBCPP_HAS_NO_EXCEPTIONS 292 throw bad_variant_access(); 293#else 294 _LIBCPP_VERBOSE_ABORT("bad_variant_access was thrown in -fno-exceptions mode"); 295#endif 296} 297 298template <class... _Types> 299class _LIBCPP_TEMPLATE_VIS variant; 300 301template <class _Tp> 302struct _LIBCPP_TEMPLATE_VIS variant_size; 303 304template <class _Tp> 305inline constexpr size_t variant_size_v = variant_size<_Tp>::value; 306 307template <class _Tp> 308struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {}; 309 310template <class _Tp> 311struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {}; 312 313template <class _Tp> 314struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> 315 : variant_size<_Tp> {}; 316 317template <class... _Types> 318struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> 319 : integral_constant<size_t, sizeof...(_Types)> {}; 320 321template <size_t _Ip, class _Tp> 322struct _LIBCPP_TEMPLATE_VIS variant_alternative; 323 324template <size_t _Ip, class _Tp> 325using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type; 326 327template <size_t _Ip, class _Tp> 328struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> 329 : add_const<variant_alternative_t<_Ip, _Tp>> {}; 330 331template <size_t _Ip, class _Tp> 332struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> 333 : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 334 335template <size_t _Ip, class _Tp> 336struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> 337 : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 338 339template <size_t _Ip, class... _Types> 340struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { 341 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 342 using type = __type_pack_element<_Ip, _Types...>; 343}; 344 345inline constexpr size_t variant_npos = static_cast<size_t>(-1); 346 347_LIBCPP_HIDE_FROM_ABI constexpr int __choose_index_type(unsigned int __num_elem) { 348 if (__num_elem < numeric_limits<unsigned char>::max()) 349 return 0; 350 if (__num_elem < numeric_limits<unsigned short>::max()) 351 return 1; 352 return 2; 353} 354 355template <size_t _NumAlts> 356using __variant_index_t = 357#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 358 unsigned int; 359#else 360 std::tuple_element_t< 361 __choose_index_type(_NumAlts), 362 std::tuple<unsigned char, unsigned short, unsigned int> 363 >; 364#endif 365 366template <class _IndexType> 367constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); 368 369template <class... _Types> 370class _LIBCPP_TEMPLATE_VIS variant; 371 372template <class... _Types> 373_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>& 374__as_variant(variant<_Types...>& __vs) noexcept { 375 return __vs; 376} 377 378template <class... _Types> 379_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>& 380__as_variant(const variant<_Types...>& __vs) noexcept { 381 return __vs; 382} 383 384template <class... _Types> 385_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>&& 386__as_variant(variant<_Types...>&& __vs) noexcept { 387 return std::move(__vs); 388} 389 390template <class... _Types> 391_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>&& 392__as_variant(const variant<_Types...>&& __vs) noexcept { 393 return std::move(__vs); 394} 395 396namespace __find_detail { 397 398template <class _Tp, class... _Types> 399_LIBCPP_HIDE_FROM_ABI 400constexpr size_t __find_index() { 401 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 402 size_t __result = __not_found; 403 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 404 if (__matches[__i]) { 405 if (__result != __not_found) { 406 return __ambiguous; 407 } 408 __result = __i; 409 } 410 } 411 return __result; 412} 413 414template <size_t _Index> 415struct __find_unambiguous_index_sfinae_impl 416 : integral_constant<size_t, _Index> {}; 417 418template <> 419struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 420 421template <> 422struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 423 424template <class _Tp, class... _Types> 425struct __find_unambiguous_index_sfinae 426 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {}; 427 428} // namespace __find_detail 429 430namespace __variant_detail { 431 432struct __valueless_t {}; 433 434enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 435 436template <typename _Tp, 437 template <typename> class _IsTriviallyAvailable, 438 template <typename> class _IsAvailable> 439constexpr _Trait __trait = 440 _IsTriviallyAvailable<_Tp>::value 441 ? _Trait::_TriviallyAvailable 442 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable; 443 444_LIBCPP_HIDE_FROM_ABI 445constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 446 _Trait __result = _Trait::_TriviallyAvailable; 447 for (_Trait __t : __traits) { 448 if (static_cast<int>(__t) > static_cast<int>(__result)) { 449 __result = __t; 450 } 451 } 452 return __result; 453} 454 455template <typename... _Types> 456struct __traits { 457 static constexpr _Trait __copy_constructible_trait = 458 __variant_detail::__common_trait({__trait<_Types, 459 is_trivially_copy_constructible, 460 is_copy_constructible>...}); 461 462 static constexpr _Trait __move_constructible_trait = 463 __variant_detail::__common_trait({__trait<_Types, 464 is_trivially_move_constructible, 465 is_move_constructible>...}); 466 467 static constexpr _Trait __copy_assignable_trait = __variant_detail::__common_trait( 468 {__copy_constructible_trait, 469 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 470 471 static constexpr _Trait __move_assignable_trait = __variant_detail::__common_trait( 472 {__move_constructible_trait, 473 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 474 475 static constexpr _Trait __destructible_trait = __variant_detail::__common_trait( 476 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 477}; 478 479namespace __access { 480 481struct __union { 482 template <class _Vp> 483 _LIBCPP_HIDE_FROM_ABI 484 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 485 return std::forward<_Vp>(__v).__head; 486 } 487 488 template <class _Vp, size_t _Ip> 489 _LIBCPP_HIDE_FROM_ABI 490 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 491 return __get_alt(std::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 492 } 493}; 494 495struct __base { 496 template <size_t _Ip, class _Vp> 497 _LIBCPP_HIDE_FROM_ABI 498 static constexpr auto&& __get_alt(_Vp&& __v) { 499 return __union::__get_alt(std::forward<_Vp>(__v).__data, 500 in_place_index<_Ip>); 501 } 502}; 503 504struct __variant { 505 template <size_t _Ip, class _Vp> 506 _LIBCPP_HIDE_FROM_ABI 507 static constexpr auto&& __get_alt(_Vp&& __v) { 508 return __base::__get_alt<_Ip>(std::forward<_Vp>(__v).__impl_); 509 } 510}; 511 512} // namespace __access 513 514namespace __visitation { 515 516struct __base { 517 template <class _Visitor, class... _Vs> 518 _LIBCPP_HIDE_FROM_ABI 519 static constexpr decltype(auto) 520 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 521 constexpr auto __fdiagonal = 522 __make_fdiagonal<_Visitor&&, 523 decltype(std::forward<_Vs>(__vs).__as_base())...>(); 524 return __fdiagonal[__index](std::forward<_Visitor>(__visitor), 525 std::forward<_Vs>(__vs).__as_base()...); 526 } 527 528 template <class _Visitor, class... _Vs> 529 _LIBCPP_HIDE_FROM_ABI 530 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 531 _Vs&&... __vs) { 532 constexpr auto __fmatrix = 533 __make_fmatrix<_Visitor&&, 534 decltype(std::forward<_Vs>(__vs).__as_base())...>(); 535 return __at(__fmatrix, __vs.index()...)( 536 std::forward<_Visitor>(__visitor), 537 std::forward<_Vs>(__vs).__as_base()...); 538 } 539 540private: 541 template <class _Tp> 542 _LIBCPP_HIDE_FROM_ABI 543 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; } 544 545 template <class _Tp, size_t _Np, typename... _Indices> 546 _LIBCPP_HIDE_FROM_ABI 547 static constexpr auto&& __at(const __farray<_Tp, _Np>& __elems, 548 size_t __index, _Indices... __indices) { 549 return __at(__elems[__index], __indices...); 550 } 551 552 template <class _Fp, class... _Fs> 553 static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_visitor_return_type_check() { 554 static_assert( 555 __all<is_same_v<_Fp, _Fs>...>::value, 556 "`std::visit` requires the visitor to have a single return type."); 557 } 558 559 template <class... _Fs> 560 _LIBCPP_HIDE_FROM_ABI 561 static constexpr auto __make_farray(_Fs&&... __fs) { 562 __std_visit_visitor_return_type_check<__remove_cvref_t<_Fs>...>(); 563 using __result = __farray<common_type_t<__remove_cvref_t<_Fs>...>, sizeof...(_Fs)>; 564 return __result{{std::forward<_Fs>(__fs)...}}; 565 } 566 567 template <size_t... _Is> 568 struct __dispatcher { 569 template <class _Fp, class... _Vs> 570 _LIBCPP_HIDE_FROM_ABI 571 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 572 return std::__invoke( 573 static_cast<_Fp>(__f), 574 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 575 } 576 }; 577 578 template <class _Fp, class... _Vs, size_t... _Is> 579 _LIBCPP_HIDE_FROM_ABI 580 static constexpr auto __make_dispatch(index_sequence<_Is...>) { 581 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 582 } 583 584 template <size_t _Ip, class _Fp, class... _Vs> 585 _LIBCPP_HIDE_FROM_ABI 586 static constexpr auto __make_fdiagonal_impl() { 587 return __make_dispatch<_Fp, _Vs...>( 588 index_sequence<((void)__type_identity<_Vs>{}, _Ip)...>{}); 589 } 590 591 template <class _Fp, class... _Vs, size_t... _Is> 592 _LIBCPP_HIDE_FROM_ABI 593 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 594 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 595 } 596 597 template <class _Fp, class _Vp, class... _Vs> 598 _LIBCPP_HIDE_FROM_ABI 599 static constexpr auto __make_fdiagonal() { 600 constexpr size_t __np = __remove_cvref_t<_Vp>::__size(); 601 static_assert(__all<(__np == __remove_cvref_t<_Vs>::__size())...>::value); 602 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<__np>{}); 603 } 604 605 template <class _Fp, class... _Vs, size_t... _Is> 606 _LIBCPP_HIDE_FROM_ABI 607 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 608 return __make_dispatch<_Fp, _Vs...>(__is); 609 } 610 611 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 612 _LIBCPP_HIDE_FROM_ABI 613 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>, 614 index_sequence<_Js...>, 615 _Ls... __ls) { 616 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>( 617 index_sequence<_Is..., _Js>{}, __ls...)...); 618 } 619 620 template <class _Fp, class... _Vs> 621 _LIBCPP_HIDE_FROM_ABI 622 static constexpr auto __make_fmatrix() { 623 return __make_fmatrix_impl<_Fp, _Vs...>( 624 index_sequence<>{}, make_index_sequence<__remove_cvref_t<_Vs>::__size()>{}...); 625 } 626}; 627 628struct __variant { 629 template <class _Visitor, class... _Vs> 630 _LIBCPP_HIDE_FROM_ABI 631 static constexpr decltype(auto) 632 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 633 return __base::__visit_alt_at(__index, 634 std::forward<_Visitor>(__visitor), 635 std::forward<_Vs>(__vs).__impl_...); 636 } 637 638 template <class _Visitor, class... _Vs> 639 _LIBCPP_HIDE_FROM_ABI 640 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 641 _Vs&&... __vs) { 642 return __base::__visit_alt( 643 std::forward<_Visitor>(__visitor), 644 std::__as_variant(std::forward<_Vs>(__vs)).__impl_...); 645 } 646 647 template <class _Visitor, class... _Vs> 648 _LIBCPP_HIDE_FROM_ABI 649 static constexpr decltype(auto) 650 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 651 return __visit_alt_at( 652 __index, 653 __make_value_visitor(std::forward<_Visitor>(__visitor)), 654 std::forward<_Vs>(__vs)...); 655 } 656 657 template <class _Visitor, class... _Vs> 658 _LIBCPP_HIDE_FROM_ABI 659 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, 660 _Vs&&... __vs) { 661 return __visit_alt( 662 __make_value_visitor(std::forward<_Visitor>(__visitor)), 663 std::forward<_Vs>(__vs)...); 664 } 665 666#if _LIBCPP_STD_VER >= 20 667 template <class _Rp, class _Visitor, class... _Vs> 668 _LIBCPP_HIDE_FROM_ABI 669 static constexpr _Rp __visit_value(_Visitor&& __visitor, 670 _Vs&&... __vs) { 671 return __visit_alt( 672 __make_value_visitor<_Rp>(std::forward<_Visitor>(__visitor)), 673 std::forward<_Vs>(__vs)...); 674 } 675#endif 676 677private: 678 template <class _Visitor, class... _Values> 679 static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_exhaustive_visitor_check() { 680 static_assert(is_invocable_v<_Visitor, _Values...>, 681 "`std::visit` requires the visitor to be exhaustive."); 682 } 683 684 template <class _Visitor> 685 struct __value_visitor { 686 template <class... _Alts> 687 _LIBCPP_HIDE_FROM_ABI 688 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 689 __std_visit_exhaustive_visitor_check< 690 _Visitor, 691 decltype((std::forward<_Alts>(__alts).__value))...>(); 692 return std::__invoke(std::forward<_Visitor>(__visitor), 693 std::forward<_Alts>(__alts).__value...); 694 } 695 _Visitor&& __visitor; 696 }; 697 698#if _LIBCPP_STD_VER >= 20 699 template <class _Rp, class _Visitor> 700 struct __value_visitor_return_type { 701 template <class... _Alts> 702 _LIBCPP_HIDE_FROM_ABI 703 constexpr _Rp operator()(_Alts&&... __alts) const { 704 __std_visit_exhaustive_visitor_check< 705 _Visitor, 706 decltype((std::forward<_Alts>(__alts).__value))...>(); 707 if constexpr (is_void_v<_Rp>) { 708 std::__invoke(std::forward<_Visitor>(__visitor), 709 std::forward<_Alts>(__alts).__value...); 710 } 711 else { 712 return std::__invoke(std::forward<_Visitor>(__visitor), 713 std::forward<_Alts>(__alts).__value...); 714 } 715 } 716 717 _Visitor&& __visitor; 718 }; 719#endif 720 721 template <class _Visitor> 722 _LIBCPP_HIDE_FROM_ABI 723 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 724 return __value_visitor<_Visitor>{std::forward<_Visitor>(__visitor)}; 725 } 726 727#if _LIBCPP_STD_VER >= 20 728 template <class _Rp, class _Visitor> 729 _LIBCPP_HIDE_FROM_ABI 730 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 731 return __value_visitor_return_type<_Rp, _Visitor>{std::forward<_Visitor>(__visitor)}; 732 } 733#endif 734}; 735 736} // namespace __visitation 737 738template <size_t _Index, class _Tp> 739struct _LIBCPP_TEMPLATE_VIS __alt { 740 using __value_type = _Tp; 741 742 template <class... _Args> 743 _LIBCPP_HIDE_FROM_ABI 744 explicit constexpr __alt(in_place_t, _Args&&... __args) 745 : __value(std::forward<_Args>(__args)...) {} 746 747 __value_type __value; 748}; 749 750template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 751union _LIBCPP_TEMPLATE_VIS __union; 752 753template <_Trait _DestructibleTrait, size_t _Index> 754union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 755 756#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 757 template <size_t _Index, class _Tp, class... _Types> \ 758 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 759 _Index, \ 760 _Tp, \ 761 _Types...> { \ 762 public: \ 763 _LIBCPP_HIDE_FROM_ABI \ 764 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 765 \ 766 template <class... _Args> \ 767 _LIBCPP_HIDE_FROM_ABI \ 768 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 769 : __head(in_place, std::forward<_Args>(__args)...) {} \ 770 \ 771 template <size_t _Ip, class... _Args> \ 772 _LIBCPP_HIDE_FROM_ABI \ 773 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 774 : __tail(in_place_index<_Ip - 1>, std::forward<_Args>(__args)...) {} \ 775 \ 776 __union(const __union&) = default; \ 777 __union(__union&&) = default; \ 778 \ 779 destructor \ 780 \ 781 __union& operator=(const __union&) = default; \ 782 __union& operator=(__union&&) = default; \ 783 \ 784 private: \ 785 char __dummy; \ 786 __alt<_Index, _Tp> __head; \ 787 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 788 \ 789 friend struct __access::__union; \ 790 } 791 792_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 793_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 794_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 795 796#undef _LIBCPP_VARIANT_UNION 797 798template <_Trait _DestructibleTrait, class... _Types> 799class _LIBCPP_TEMPLATE_VIS __base { 800public: 801 using __index_t = __variant_index_t<sizeof...(_Types)>; 802 803 _LIBCPP_HIDE_FROM_ABI 804 explicit constexpr __base(__valueless_t __tag) noexcept 805 : __data(__tag), __index(__variant_npos<__index_t>) {} 806 807 template <size_t _Ip, class... _Args> 808 _LIBCPP_HIDE_FROM_ABI 809 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 810 : 811 __data(in_place_index<_Ip>, std::forward<_Args>(__args)...), 812 __index(_Ip) {} 813 814 _LIBCPP_HIDE_FROM_ABI 815 constexpr bool valueless_by_exception() const noexcept { 816 return index() == variant_npos; 817 } 818 819 _LIBCPP_HIDE_FROM_ABI 820 constexpr size_t index() const noexcept { 821 return __index == __variant_npos<__index_t> ? variant_npos : __index; 822 } 823 824protected: 825 _LIBCPP_HIDE_FROM_ABI 826 constexpr auto&& __as_base() & { return *this; } 827 828 _LIBCPP_HIDE_FROM_ABI 829 constexpr auto&& __as_base() && { return std::move(*this); } 830 831 _LIBCPP_HIDE_FROM_ABI 832 constexpr auto&& __as_base() const & { return *this; } 833 834 _LIBCPP_HIDE_FROM_ABI 835 constexpr auto&& __as_base() const && { return std::move(*this); } 836 837 _LIBCPP_HIDE_FROM_ABI 838 static constexpr size_t __size() { return sizeof...(_Types); } 839 840 __union<_DestructibleTrait, 0, _Types...> __data; 841 __index_t __index; 842 843 friend struct __access::__base; 844 friend struct __visitation::__base; 845}; 846 847template <class _Traits, _Trait = _Traits::__destructible_trait> 848class _LIBCPP_TEMPLATE_VIS __dtor; 849 850#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 851 template <class... _Types> \ 852 class _LIBCPP_TEMPLATE_VIS __dtor<__traits<_Types...>, \ 853 destructible_trait> \ 854 : public __base<destructible_trait, _Types...> { \ 855 using __base_type = __base<destructible_trait, _Types...>; \ 856 using __index_t = typename __base_type::__index_t; \ 857 \ 858 public: \ 859 using __base_type::__base_type; \ 860 using __base_type::operator=; \ 861 \ 862 __dtor(const __dtor&) = default; \ 863 __dtor(__dtor&&) = default; \ 864 destructor \ 865 __dtor& operator=(const __dtor&) = default; \ 866 __dtor& operator=(__dtor&&) = default; \ 867 \ 868 protected: \ 869 inline _LIBCPP_HIDE_FROM_ABI \ 870 destroy \ 871 } 872 873_LIBCPP_VARIANT_DESTRUCTOR( 874 _Trait::_TriviallyAvailable, 875 ~__dtor() = default;, 876 void __destroy() noexcept { this->__index = __variant_npos<__index_t>; }); 877 878_LIBCPP_VARIANT_DESTRUCTOR( 879 _Trait::_Available, 880 ~__dtor() { __destroy(); }, 881 void __destroy() noexcept { 882 if (!this->valueless_by_exception()) { 883 __visitation::__base::__visit_alt( 884 [](auto& __alt) noexcept { 885 using __alt_type = __remove_cvref_t<decltype(__alt)>; 886 __alt.~__alt_type(); 887 }, 888 *this); 889 } 890 this->__index = __variant_npos<__index_t>; 891 }); 892 893_LIBCPP_VARIANT_DESTRUCTOR( 894 _Trait::_Unavailable, 895 ~__dtor() = delete;, 896 void __destroy() noexcept = delete;); 897 898#undef _LIBCPP_VARIANT_DESTRUCTOR 899 900template <class _Traits> 901class _LIBCPP_TEMPLATE_VIS __ctor : public __dtor<_Traits> { 902 using __base_type = __dtor<_Traits>; 903 904public: 905 using __base_type::__base_type; 906 using __base_type::operator=; 907 908protected: 909 template <size_t _Ip, class _Tp, class... _Args> 910 _LIBCPP_HIDE_FROM_ABI 911 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 912 ::new ((void*)std::addressof(__a)) 913 __alt<_Ip, _Tp>(in_place, std::forward<_Args>(__args)...); 914 return __a.__value; 915 } 916 917 template <class _Rhs> 918 _LIBCPP_HIDE_FROM_ABI 919 static void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) { 920 __lhs.__destroy(); 921 if (!__rhs.valueless_by_exception()) { 922 __visitation::__base::__visit_alt_at( 923 __rhs.index(), 924 [](auto& __lhs_alt, auto&& __rhs_alt) { 925 __construct_alt( 926 __lhs_alt, 927 std::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 928 }, 929 __lhs, std::forward<_Rhs>(__rhs)); 930 __lhs.__index = __rhs.index(); 931 } 932 } 933}; 934 935template <class _Traits, _Trait = _Traits::__move_constructible_trait> 936class _LIBCPP_TEMPLATE_VIS __move_constructor; 937 938#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 939 move_constructor) \ 940 template <class... _Types> \ 941 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 942 move_constructible_trait> \ 943 : public __ctor<__traits<_Types...>> { \ 944 using __base_type = __ctor<__traits<_Types...>>; \ 945 \ 946 public: \ 947 using __base_type::__base_type; \ 948 using __base_type::operator=; \ 949 \ 950 __move_constructor(const __move_constructor&) = default; \ 951 move_constructor \ 952 ~__move_constructor() = default; \ 953 __move_constructor& operator=(const __move_constructor&) = default; \ 954 __move_constructor& operator=(__move_constructor&&) = default; \ 955 } 956 957_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 958 _Trait::_TriviallyAvailable, 959 __move_constructor(__move_constructor&& __that) = default;); 960 961_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 962 _Trait::_Available, 963 __move_constructor(__move_constructor&& __that) noexcept( 964 __all<is_nothrow_move_constructible_v<_Types>...>::value) 965 : __move_constructor(__valueless_t{}) { 966 this->__generic_construct(*this, std::move(__that)); 967 }); 968 969_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 970 _Trait::_Unavailable, 971 __move_constructor(__move_constructor&&) = delete;); 972 973#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 974 975template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 976class _LIBCPP_TEMPLATE_VIS __copy_constructor; 977 978#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 979 copy_constructor) \ 980 template <class... _Types> \ 981 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 982 copy_constructible_trait> \ 983 : public __move_constructor<__traits<_Types...>> { \ 984 using __base_type = __move_constructor<__traits<_Types...>>; \ 985 \ 986 public: \ 987 using __base_type::__base_type; \ 988 using __base_type::operator=; \ 989 \ 990 copy_constructor \ 991 __copy_constructor(__copy_constructor&&) = default; \ 992 ~__copy_constructor() = default; \ 993 __copy_constructor& operator=(const __copy_constructor&) = default; \ 994 __copy_constructor& operator=(__copy_constructor&&) = default; \ 995 } 996 997_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 998 _Trait::_TriviallyAvailable, 999 __copy_constructor(const __copy_constructor& __that) = default;); 1000 1001_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 1002 _Trait::_Available, 1003 __copy_constructor(const __copy_constructor& __that) 1004 : __copy_constructor(__valueless_t{}) { 1005 this->__generic_construct(*this, __that); 1006 }); 1007 1008_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 1009 _Trait::_Unavailable, 1010 __copy_constructor(const __copy_constructor&) = delete;); 1011 1012#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 1013 1014template <class _Traits> 1015class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 1016 using __base_type = __copy_constructor<_Traits>; 1017 1018public: 1019 using __base_type::__base_type; 1020 using __base_type::operator=; 1021 1022 template <size_t _Ip, class... _Args> 1023 _LIBCPP_HIDE_FROM_ABI 1024 auto& __emplace(_Args&&... __args) { 1025 this->__destroy(); 1026 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 1027 std::forward<_Args>(__args)...); 1028 this->__index = _Ip; 1029 return __res; 1030 } 1031 1032protected: 1033 template <size_t _Ip, class _Tp, class _Arg> 1034 _LIBCPP_HIDE_FROM_ABI 1035 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 1036 if (this->index() == _Ip) { 1037 __a.__value = std::forward<_Arg>(__arg); 1038 } else { 1039 struct { 1040 _LIBCPP_HIDE_FROM_ABI void operator()(true_type) const { 1041 __this->__emplace<_Ip>(std::forward<_Arg>(__arg)); 1042 } 1043 _LIBCPP_HIDE_FROM_ABI void operator()(false_type) const { 1044 __this->__emplace<_Ip>(_Tp(std::forward<_Arg>(__arg))); 1045 } 1046 __assignment* __this; 1047 _Arg&& __arg; 1048 } __impl{this, std::forward<_Arg>(__arg)}; 1049 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> || 1050 !is_nothrow_move_constructible_v<_Tp>>{}); 1051 } 1052 } 1053 1054 template <class _That> 1055 _LIBCPP_HIDE_FROM_ABI 1056 void __generic_assign(_That&& __that) { 1057 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1058 // do nothing. 1059 } else if (__that.valueless_by_exception()) { 1060 this->__destroy(); 1061 } else { 1062 __visitation::__base::__visit_alt_at( 1063 __that.index(), 1064 [this](auto& __this_alt, auto&& __that_alt) { 1065 this->__assign_alt( 1066 __this_alt, 1067 std::forward<decltype(__that_alt)>(__that_alt).__value); 1068 }, 1069 *this, std::forward<_That>(__that)); 1070 } 1071 } 1072}; 1073 1074template <class _Traits, _Trait = _Traits::__move_assignable_trait> 1075class _LIBCPP_TEMPLATE_VIS __move_assignment; 1076 1077#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 1078 move_assignment) \ 1079 template <class... _Types> \ 1080 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 1081 move_assignable_trait> \ 1082 : public __assignment<__traits<_Types...>> { \ 1083 using __base_type = __assignment<__traits<_Types...>>; \ 1084 \ 1085 public: \ 1086 using __base_type::__base_type; \ 1087 using __base_type::operator=; \ 1088 \ 1089 __move_assignment(const __move_assignment&) = default; \ 1090 __move_assignment(__move_assignment&&) = default; \ 1091 ~__move_assignment() = default; \ 1092 __move_assignment& operator=(const __move_assignment&) = default; \ 1093 move_assignment \ 1094 } 1095 1096_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1097 _Trait::_TriviallyAvailable, 1098 __move_assignment& operator=(__move_assignment&& __that) = default;); 1099 1100_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1101 _Trait::_Available, 1102 __move_assignment& operator=(__move_assignment&& __that) noexcept( 1103 __all<(is_nothrow_move_constructible_v<_Types> && 1104 is_nothrow_move_assignable_v<_Types>)...>::value) { 1105 this->__generic_assign(std::move(__that)); 1106 return *this; 1107 }); 1108 1109_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1110 _Trait::_Unavailable, 1111 __move_assignment& operator=(__move_assignment&&) = delete;); 1112 1113#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 1114 1115template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 1116class _LIBCPP_TEMPLATE_VIS __copy_assignment; 1117 1118#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 1119 copy_assignment) \ 1120 template <class... _Types> \ 1121 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 1122 copy_assignable_trait> \ 1123 : public __move_assignment<__traits<_Types...>> { \ 1124 using __base_type = __move_assignment<__traits<_Types...>>; \ 1125 \ 1126 public: \ 1127 using __base_type::__base_type; \ 1128 using __base_type::operator=; \ 1129 \ 1130 __copy_assignment(const __copy_assignment&) = default; \ 1131 __copy_assignment(__copy_assignment&&) = default; \ 1132 ~__copy_assignment() = default; \ 1133 copy_assignment \ 1134 __copy_assignment& operator=(__copy_assignment&&) = default; \ 1135 } 1136 1137_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1138 _Trait::_TriviallyAvailable, 1139 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 1140 1141_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1142 _Trait::_Available, 1143 __copy_assignment& operator=(const __copy_assignment& __that) { 1144 this->__generic_assign(__that); 1145 return *this; 1146 }); 1147 1148_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1149 _Trait::_Unavailable, 1150 __copy_assignment& operator=(const __copy_assignment&) = delete;); 1151 1152#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1153 1154template <class... _Types> 1155class _LIBCPP_TEMPLATE_VIS __impl 1156 : public __copy_assignment<__traits<_Types...>> { 1157 using __base_type = __copy_assignment<__traits<_Types...>>; 1158 1159public: 1160 using __base_type::__base_type; // get in_place_index_t constructor & friends 1161 _LIBCPP_HIDE_FROM_ABI __impl(__impl const&) = default; 1162 _LIBCPP_HIDE_FROM_ABI __impl(__impl&&) = default; 1163 _LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl const&) = default; 1164 _LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl&&) = default; 1165 1166 template <size_t _Ip, class _Arg> 1167 _LIBCPP_HIDE_FROM_ABI 1168 void __assign(_Arg&& __arg) { 1169 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1170 std::forward<_Arg>(__arg)); 1171 } 1172 1173 inline _LIBCPP_HIDE_FROM_ABI 1174 void __swap(__impl& __that) { 1175 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1176 // do nothing. 1177 } else if (this->index() == __that.index()) { 1178 __visitation::__base::__visit_alt_at( 1179 this->index(), 1180 [](auto& __this_alt, auto& __that_alt) { 1181 using std::swap; 1182 swap(__this_alt.__value, __that_alt.__value); 1183 }, 1184 *this, 1185 __that); 1186 } else { 1187 __impl* __lhs = this; 1188 __impl* __rhs = std::addressof(__that); 1189 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1190 std::swap(__lhs, __rhs); 1191 } 1192 __impl __tmp(std::move(*__rhs)); 1193#ifndef _LIBCPP_HAS_NO_EXCEPTIONS 1194 if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) { 1195 this->__generic_construct(*__rhs, std::move(*__lhs)); 1196 } else { 1197 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1198 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1199 // into `__rhs` and provide the strong exception safety guarantee. 1200 try { 1201 this->__generic_construct(*__rhs, std::move(*__lhs)); 1202 } catch (...) { 1203 if (__tmp.__move_nothrow()) { 1204 this->__generic_construct(*__rhs, std::move(__tmp)); 1205 } 1206 throw; 1207 } 1208 } 1209#else 1210 // this isn't consolidated with the `if constexpr` branch above due to 1211 // `throw` being ill-formed with exceptions disabled even when discarded. 1212 this->__generic_construct(*__rhs, std::move(*__lhs)); 1213#endif 1214 this->__generic_construct(*__lhs, std::move(__tmp)); 1215 } 1216 } 1217 1218private: 1219 inline _LIBCPP_HIDE_FROM_ABI 1220 bool __move_nothrow() const { 1221 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1222 return this->valueless_by_exception() || __results[this->index()]; 1223 } 1224}; 1225 1226struct __no_narrowing_check { 1227 template <class _Dest, class _Source> 1228 using _Apply = __type_identity<_Dest>; 1229}; 1230 1231struct __narrowing_check { 1232 template <class _Dest> 1233 static auto __test_impl(_Dest (&&)[1]) -> __type_identity<_Dest>; 1234 template <class _Dest, class _Source> 1235 using _Apply _LIBCPP_NODEBUG = decltype(__test_impl<_Dest>({std::declval<_Source>()})); 1236}; 1237 1238template <class _Dest, class _Source> 1239using __check_for_narrowing _LIBCPP_NODEBUG = 1240 typename _If< 1241#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT 1242 false && 1243#endif 1244 is_arithmetic<_Dest>::value, 1245 __narrowing_check, 1246 __no_narrowing_check 1247 >::template _Apply<_Dest, _Source>; 1248 1249template <class _Tp, size_t _Idx> 1250struct __overload { 1251 template <class _Up> 1252 auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>; 1253}; 1254 1255// TODO(LLVM-19): Remove all occurrences of this macro. 1256#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT 1257template <class _Tp, size_t> 1258struct __overload_bool { 1259 template <class _Up, class _Ap = __remove_cvref_t<_Up>> 1260 auto operator()(bool, _Up&&) const 1261 -> enable_if_t<is_same_v<_Ap, bool>, __type_identity<_Tp>>; 1262}; 1263 1264template <size_t _Idx> 1265struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {}; 1266template <size_t _Idx> 1267struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {}; 1268template <size_t _Idx> 1269struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {}; 1270template <size_t _Idx> 1271struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {}; 1272#endif 1273 1274template <class ..._Bases> 1275struct __all_overloads : _Bases... { 1276 void operator()() const; 1277 using _Bases::operator()...; 1278}; 1279 1280template <class _IdxSeq> 1281struct __make_overloads_imp; 1282 1283template <size_t ..._Idx> 1284struct __make_overloads_imp<__tuple_indices<_Idx...> > { 1285 template <class ..._Types> 1286 using _Apply _LIBCPP_NODEBUG = __all_overloads<__overload<_Types, _Idx>...>; 1287}; 1288 1289template <class ..._Types> 1290using _MakeOverloads _LIBCPP_NODEBUG = typename __make_overloads_imp< 1291 __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>; 1292 1293template <class _Tp, class... _Types> 1294using __best_match_t = 1295 typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type; 1296 1297} // namespace __variant_detail 1298 1299template <class... _Types> 1300class _LIBCPP_TEMPLATE_VIS _LIBCPP_DECLSPEC_EMPTY_BASES variant 1301 : private __sfinae_ctor_base< 1302 __all<is_copy_constructible_v<_Types>...>::value, 1303 __all<is_move_constructible_v<_Types>...>::value>, 1304 private __sfinae_assign_base< 1305 __all<(is_copy_constructible_v<_Types> && 1306 is_copy_assignable_v<_Types>)...>::value, 1307 __all<(is_move_constructible_v<_Types> && 1308 is_move_assignable_v<_Types>)...>::value> { 1309 static_assert(0 < sizeof...(_Types), 1310 "variant must consist of at least one alternative."); 1311 1312 static_assert(__all<!is_array_v<_Types>...>::value, 1313 "variant can not have an array type as an alternative."); 1314 1315 static_assert(__all<!is_reference_v<_Types>...>::value, 1316 "variant can not have a reference type as an alternative."); 1317 1318 static_assert(__all<!is_void_v<_Types>...>::value, 1319 "variant can not have a void type as an alternative."); 1320 1321 using __first_type = variant_alternative_t<0, variant>; 1322 1323public: 1324 template <bool _Dummy = true, 1325 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1326 _Dummy>::value, 1327 int> = 0> 1328 _LIBCPP_HIDE_FROM_ABI 1329 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1330 : __impl_(in_place_index<0>) {} 1331 1332 _LIBCPP_HIDE_FROM_ABI constexpr variant(const variant&) = default; 1333 _LIBCPP_HIDE_FROM_ABI constexpr variant(variant&&) = default; 1334 1335 template < 1336 class _Arg, 1337 enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0, 1338 enable_if_t<!__is_inplace_type<__remove_cvref_t<_Arg>>::value, int> = 0, 1339 enable_if_t<!__is_inplace_index<__remove_cvref_t<_Arg>>::value, int> = 0, 1340 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1341 size_t _Ip = 1342 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1343 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1344 _LIBCPP_HIDE_FROM_ABI 1345 constexpr variant(_Arg&& __arg) noexcept( 1346 is_nothrow_constructible_v<_Tp, _Arg>) 1347 : __impl_(in_place_index<_Ip>, std::forward<_Arg>(__arg)) {} 1348 1349 template <size_t _Ip, class... _Args, 1350 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1351 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1352 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1353 _LIBCPP_HIDE_FROM_ABI 1354 explicit constexpr variant( 1355 in_place_index_t<_Ip>, 1356 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1357 : __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {} 1358 1359 template < 1360 size_t _Ip, 1361 class _Up, 1362 class... _Args, 1363 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1364 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1365 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1366 int> = 0> 1367 _LIBCPP_HIDE_FROM_ABI 1368 explicit constexpr variant( 1369 in_place_index_t<_Ip>, 1370 initializer_list<_Up> __il, 1371 _Args&&... __args) noexcept( 1372 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1373 : __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {} 1374 1375 template < 1376 class _Tp, 1377 class... _Args, 1378 size_t _Ip = 1379 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1380 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1381 _LIBCPP_HIDE_FROM_ABI 1382 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1383 is_nothrow_constructible_v<_Tp, _Args...>) 1384 : __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {} 1385 1386 template < 1387 class _Tp, 1388 class _Up, 1389 class... _Args, 1390 size_t _Ip = 1391 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1392 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1393 int> = 0> 1394 _LIBCPP_HIDE_FROM_ABI 1395 explicit constexpr variant( 1396 in_place_type_t<_Tp>, 1397 initializer_list<_Up> __il, 1398 _Args&&... __args) noexcept( 1399 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1400 : __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {} 1401 1402 _LIBCPP_HIDE_FROM_ABI ~variant() = default; 1403 1404 _LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(const variant&) = default; 1405 _LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(variant&&) = default; 1406 1407 template < 1408 class _Arg, 1409 enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0, 1410 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1411 size_t _Ip = 1412 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1413 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1414 int> = 0> 1415 _LIBCPP_HIDE_FROM_ABI 1416 variant& operator=(_Arg&& __arg) noexcept( 1417 is_nothrow_assignable_v<_Tp&, _Arg> && 1418 is_nothrow_constructible_v<_Tp, _Arg>) { 1419 __impl_.template __assign<_Ip>(std::forward<_Arg>(__arg)); 1420 return *this; 1421 } 1422 1423 template < 1424 size_t _Ip, 1425 class... _Args, 1426 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1427 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1428 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1429 _LIBCPP_HIDE_FROM_ABI 1430 _Tp& emplace(_Args&&... __args) { 1431 return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...); 1432 } 1433 1434 template < 1435 size_t _Ip, 1436 class _Up, 1437 class... _Args, 1438 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1439 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1440 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1441 int> = 0> 1442 _LIBCPP_HIDE_FROM_ABI 1443 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1444 return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...); 1445 } 1446 1447 template < 1448 class _Tp, 1449 class... _Args, 1450 size_t _Ip = 1451 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1452 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1453 _LIBCPP_HIDE_FROM_ABI 1454 _Tp& emplace(_Args&&... __args) { 1455 return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...); 1456 } 1457 1458 template < 1459 class _Tp, 1460 class _Up, 1461 class... _Args, 1462 size_t _Ip = 1463 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1464 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1465 int> = 0> 1466 _LIBCPP_HIDE_FROM_ABI 1467 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1468 return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...); 1469 } 1470 1471 _LIBCPP_HIDE_FROM_ABI 1472 constexpr bool valueless_by_exception() const noexcept { 1473 return __impl_.valueless_by_exception(); 1474 } 1475 1476 _LIBCPP_HIDE_FROM_ABI 1477 constexpr size_t index() const noexcept { return __impl_.index(); } 1478 1479 template < 1480 bool _Dummy = true, 1481 enable_if_t< 1482 __all<( 1483 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1484 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1485 int> = 0> 1486 _LIBCPP_HIDE_FROM_ABI 1487 void swap(variant& __that) noexcept( 1488 __all<(is_nothrow_move_constructible_v<_Types> && 1489 is_nothrow_swappable_v<_Types>)...>::value) { 1490 __impl_.__swap(__that.__impl_); 1491 } 1492 1493private: 1494 __variant_detail::__impl<_Types...> __impl_; 1495 1496 friend struct __variant_detail::__access::__variant; 1497 friend struct __variant_detail::__visitation::__variant; 1498}; 1499 1500template <size_t _Ip, class... _Types> 1501_LIBCPP_HIDE_FROM_ABI 1502constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1503 return __v.index() == _Ip; 1504} 1505 1506template <class _Tp, class... _Types> 1507_LIBCPP_HIDE_FROM_ABI 1508constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1509 return std::__holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1510} 1511 1512template <size_t _Ip, class _Vp> 1513_LIBCPP_HIDE_FROM_ABI 1514_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1515constexpr auto&& __generic_get(_Vp&& __v) { 1516 using __variant_detail::__access::__variant; 1517 if (!std::__holds_alternative<_Ip>(__v)) { 1518 __throw_bad_variant_access(); 1519 } 1520 return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value; 1521} 1522 1523template <size_t _Ip, class... _Types> 1524_LIBCPP_HIDE_FROM_ABI 1525_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1526constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1527 variant<_Types...>& __v) { 1528 static_assert(_Ip < sizeof...(_Types)); 1529 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1530 return std::__generic_get<_Ip>(__v); 1531} 1532 1533template <size_t _Ip, class... _Types> 1534_LIBCPP_HIDE_FROM_ABI 1535_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1536constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1537 variant<_Types...>&& __v) { 1538 static_assert(_Ip < sizeof...(_Types)); 1539 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1540 return std::__generic_get<_Ip>(std::move(__v)); 1541} 1542 1543template <size_t _Ip, class... _Types> 1544_LIBCPP_HIDE_FROM_ABI 1545_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1546constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1547 const variant<_Types...>& __v) { 1548 static_assert(_Ip < sizeof...(_Types)); 1549 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1550 return std::__generic_get<_Ip>(__v); 1551} 1552 1553template <size_t _Ip, class... _Types> 1554_LIBCPP_HIDE_FROM_ABI 1555_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1556constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1557 const variant<_Types...>&& __v) { 1558 static_assert(_Ip < sizeof...(_Types)); 1559 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1560 return std::__generic_get<_Ip>(std::move(__v)); 1561} 1562 1563template <class _Tp, class... _Types> 1564_LIBCPP_HIDE_FROM_ABI 1565_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1566constexpr _Tp& get(variant<_Types...>& __v) { 1567 static_assert(!is_void_v<_Tp>); 1568 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1569} 1570 1571template <class _Tp, class... _Types> 1572_LIBCPP_HIDE_FROM_ABI 1573_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1574constexpr _Tp&& get(variant<_Types...>&& __v) { 1575 static_assert(!is_void_v<_Tp>); 1576 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1577 std::move(__v)); 1578} 1579 1580template <class _Tp, class... _Types> 1581_LIBCPP_HIDE_FROM_ABI 1582_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1583constexpr const _Tp& get(const variant<_Types...>& __v) { 1584 static_assert(!is_void_v<_Tp>); 1585 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1586} 1587 1588template <class _Tp, class... _Types> 1589_LIBCPP_HIDE_FROM_ABI 1590_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1591constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1592 static_assert(!is_void_v<_Tp>); 1593 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1594 std::move(__v)); 1595} 1596 1597template <size_t _Ip, class _Vp> 1598_LIBCPP_HIDE_FROM_ABI 1599constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1600 using __variant_detail::__access::__variant; 1601 return __v && std::__holds_alternative<_Ip>(*__v) 1602 ? std::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1603 : nullptr; 1604} 1605 1606template <size_t _Ip, class... _Types> 1607_LIBCPP_HIDE_FROM_ABI 1608constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1609get_if(variant<_Types...>* __v) noexcept { 1610 static_assert(_Ip < sizeof...(_Types)); 1611 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1612 return std::__generic_get_if<_Ip>(__v); 1613} 1614 1615template <size_t _Ip, class... _Types> 1616_LIBCPP_HIDE_FROM_ABI 1617constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1618get_if(const variant<_Types...>* __v) noexcept { 1619 static_assert(_Ip < sizeof...(_Types)); 1620 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1621 return std::__generic_get_if<_Ip>(__v); 1622} 1623 1624template <class _Tp, class... _Types> 1625_LIBCPP_HIDE_FROM_ABI 1626constexpr add_pointer_t<_Tp> 1627get_if(variant<_Types...>* __v) noexcept { 1628 static_assert(!is_void_v<_Tp>); 1629 return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1630} 1631 1632template <class _Tp, class... _Types> 1633_LIBCPP_HIDE_FROM_ABI 1634constexpr add_pointer_t<const _Tp> 1635get_if(const variant<_Types...>* __v) noexcept { 1636 static_assert(!is_void_v<_Tp>); 1637 return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1638} 1639 1640template <class _Operator> 1641struct __convert_to_bool { 1642 template <class _T1, class _T2> 1643 _LIBCPP_HIDE_FROM_ABI 1644 constexpr bool operator()(_T1 && __t1, _T2&& __t2) const { 1645 static_assert(is_convertible<decltype(_Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2))), bool>::value, 1646 "the relational operator does not return a type which is implicitly convertible to bool"); 1647 return _Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2)); 1648 } 1649}; 1650 1651template <class... _Types> 1652_LIBCPP_HIDE_FROM_ABI 1653constexpr bool operator==(const variant<_Types...>& __lhs, 1654 const variant<_Types...>& __rhs) { 1655 using __variant_detail::__visitation::__variant; 1656 if (__lhs.index() != __rhs.index()) return false; 1657 if (__lhs.valueless_by_exception()) return true; 1658 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs); 1659} 1660 1661# if _LIBCPP_STD_VER >= 20 1662 1663template <class... _Types> requires (three_way_comparable<_Types> && ...) 1664_LIBCPP_HIDE_FROM_ABI constexpr common_comparison_category_t<compare_three_way_result_t<_Types>...> 1665operator<=>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1666 using __variant_detail::__visitation::__variant; 1667 using __result_t = common_comparison_category_t<compare_three_way_result_t<_Types>...>; 1668 if (__lhs.valueless_by_exception() && __rhs.valueless_by_exception()) 1669 return strong_ordering::equal; 1670 if (__lhs.valueless_by_exception()) 1671 return strong_ordering::less; 1672 if (__rhs.valueless_by_exception()) 1673 return strong_ordering::greater; 1674 if (auto __c = __lhs.index() <=> __rhs.index(); __c != 0) 1675 return __c; 1676 auto __three_way = []<class _Type>(const _Type& __v, const _Type& __w) -> __result_t { return __v <=> __w; }; 1677 return __variant::__visit_value_at(__lhs.index(), __three_way, __lhs, __rhs); 1678} 1679 1680# endif // _LIBCPP_STD_VER >= 20 1681 1682template <class... _Types> 1683_LIBCPP_HIDE_FROM_ABI 1684constexpr bool operator!=(const variant<_Types...>& __lhs, 1685 const variant<_Types...>& __rhs) { 1686 using __variant_detail::__visitation::__variant; 1687 if (__lhs.index() != __rhs.index()) return true; 1688 if (__lhs.valueless_by_exception()) return false; 1689 return __variant::__visit_value_at( 1690 __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs); 1691} 1692 1693template <class... _Types> 1694_LIBCPP_HIDE_FROM_ABI 1695constexpr bool operator<(const variant<_Types...>& __lhs, 1696 const variant<_Types...>& __rhs) { 1697 using __variant_detail::__visitation::__variant; 1698 if (__rhs.valueless_by_exception()) return false; 1699 if (__lhs.valueless_by_exception()) return true; 1700 if (__lhs.index() < __rhs.index()) return true; 1701 if (__lhs.index() > __rhs.index()) return false; 1702 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs); 1703} 1704 1705template <class... _Types> 1706_LIBCPP_HIDE_FROM_ABI 1707constexpr bool operator>(const variant<_Types...>& __lhs, 1708 const variant<_Types...>& __rhs) { 1709 using __variant_detail::__visitation::__variant; 1710 if (__lhs.valueless_by_exception()) return false; 1711 if (__rhs.valueless_by_exception()) return true; 1712 if (__lhs.index() > __rhs.index()) return true; 1713 if (__lhs.index() < __rhs.index()) return false; 1714 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs); 1715} 1716 1717template <class... _Types> 1718_LIBCPP_HIDE_FROM_ABI 1719constexpr bool operator<=(const variant<_Types...>& __lhs, 1720 const variant<_Types...>& __rhs) { 1721 using __variant_detail::__visitation::__variant; 1722 if (__lhs.valueless_by_exception()) return true; 1723 if (__rhs.valueless_by_exception()) return false; 1724 if (__lhs.index() < __rhs.index()) return true; 1725 if (__lhs.index() > __rhs.index()) return false; 1726 return __variant::__visit_value_at( 1727 __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs); 1728} 1729 1730template <class... _Types> 1731_LIBCPP_HIDE_FROM_ABI 1732constexpr bool operator>=(const variant<_Types...>& __lhs, 1733 const variant<_Types...>& __rhs) { 1734 using __variant_detail::__visitation::__variant; 1735 if (__rhs.valueless_by_exception()) return true; 1736 if (__lhs.valueless_by_exception()) return false; 1737 if (__lhs.index() > __rhs.index()) return true; 1738 if (__lhs.index() < __rhs.index()) return false; 1739 return __variant::__visit_value_at( 1740 __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs); 1741} 1742 1743template <class... _Vs> 1744_LIBCPP_HIDE_FROM_ABI 1745_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1746constexpr void __throw_if_valueless(_Vs&&... __vs) { 1747 const bool __valueless = 1748 (... || std::__as_variant(__vs).valueless_by_exception()); 1749 if (__valueless) { 1750 __throw_bad_variant_access(); 1751 } 1752} 1753 1754template < 1755 class _Visitor, class... _Vs, 1756 typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...> > 1757_LIBCPP_HIDE_FROM_ABI 1758_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1759constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1760 using __variant_detail::__visitation::__variant; 1761 std::__throw_if_valueless(std::forward<_Vs>(__vs)...); 1762 return __variant::__visit_value(std::forward<_Visitor>(__visitor), 1763 std::forward<_Vs>(__vs)...); 1764} 1765 1766#if _LIBCPP_STD_VER >= 20 1767template < 1768 class _Rp, class _Visitor, class... _Vs, 1769 typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...> > 1770_LIBCPP_HIDE_FROM_ABI 1771_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1772constexpr _Rp visit(_Visitor&& __visitor, _Vs&&... __vs) { 1773 using __variant_detail::__visitation::__variant; 1774 std::__throw_if_valueless(std::forward<_Vs>(__vs)...); 1775 return __variant::__visit_value<_Rp>(std::forward<_Visitor>(__visitor), 1776 std::forward<_Vs>(__vs)...); 1777} 1778#endif 1779 1780template <class... _Types> 1781_LIBCPP_HIDE_FROM_ABI 1782auto swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) 1783 noexcept(noexcept(__lhs.swap(__rhs))) 1784 -> decltype( __lhs.swap(__rhs)) 1785 { return __lhs.swap(__rhs); } 1786 1787template <class... _Types> 1788struct _LIBCPP_TEMPLATE_VIS hash< 1789 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1790 using argument_type = variant<_Types...>; 1791 using result_type = size_t; 1792 1793 _LIBCPP_HIDE_FROM_ABI 1794 result_type operator()(const argument_type& __v) const { 1795 using __variant_detail::__visitation::__variant; 1796 size_t __res = 1797 __v.valueless_by_exception() 1798 ? 299792458 // Random value chosen by the universe upon creation 1799 : __variant::__visit_alt( 1800 [](const auto& __alt) { 1801 using __alt_type = __remove_cvref_t<decltype(__alt)>; 1802 using __value_type = remove_const_t< 1803 typename __alt_type::__value_type>; 1804 return hash<__value_type>{}(__alt.__value); 1805 }, 1806 __v); 1807 return std::__hash_combine(__res, hash<size_t>{}(__v.index())); 1808 } 1809}; 1810 1811// __unchecked_get is the same as std::get, except, it is UB to use it with the wrong 1812// type whereas std::get will throw or returning nullptr. This makes it faster than 1813// std::get. 1814template <size_t _Ip, class _Vp> 1815_LIBCPP_HIDE_FROM_ABI 1816constexpr auto&& __unchecked_get(_Vp&& __v) noexcept { 1817 using __variant_detail::__access::__variant; 1818 return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value; 1819} 1820 1821template <class _Tp, class... _Types> 1822_LIBCPP_HIDE_FROM_ABI 1823constexpr auto&& __unchecked_get(const variant<_Types...>& __v) noexcept { 1824 return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1825} 1826 1827template <class _Tp, class... _Types> 1828_LIBCPP_HIDE_FROM_ABI 1829constexpr auto&& __unchecked_get(variant<_Types...>& __v) noexcept { 1830 return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1831} 1832 1833#endif // _LIBCPP_STD_VER >= 17 1834 1835_LIBCPP_END_NAMESPACE_STD 1836 1837_LIBCPP_POP_MACROS 1838 1839#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 1840# include <exception> 1841# include <type_traits> 1842# include <typeinfo> 1843# include <utility> 1844#endif 1845 1846#endif // _LIBCPP_VARIANT 1847