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 constexpr ~variant(); // constexpr since c++20 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> 52 constexpr variant& operator=(T&&) noexcept(see below); // constexpr since c++20 53 54 // 20.7.2.4, modifiers 55 template <class T, class... Args> 56 constexpr T& emplace(Args&&...); // constexpr since c++20 57 58 template <class T, class U, class... Args> 59 constexpr T& emplace(initializer_list<U>, Args&&...); // constexpr since c++20 60 61 template <size_t I, class... Args> 62 constexpr variant_alternative_t<I, variant>& emplace(Args&&...); // constexpr since c++20 63 64 template <size_t I, class U, class... Args> 65 constexpr variant_alternative_t<I, variant>& 66 emplace(initializer_list<U>, Args&&...); // constexpr since c++20 67 68 // 20.7.2.5, value status 69 constexpr bool valueless_by_exception() const noexcept; 70 constexpr size_t index() const noexcept; 71 72 // 20.7.2.6, swap 73 void swap(variant&) noexcept(see below); 74 75 // [variant.visit], visitation 76 template<class Self, class Visitor> 77 constexpr decltype(auto) visit(this Self&&, Visitor&&); // Since C++26 78 template<class R, class Self, class Visitor> 79 constexpr R visit(this Self&&, Visitor&&); // Since C++26 80 }; 81 82 // 20.7.3, variant helper classes 83 template <class T> struct variant_size; // undefined 84 85 template <class T> 86 inline constexpr size_t variant_size_v = variant_size<T>::value; 87 88 template <class T> struct variant_size<const T>; 89 template <class T> struct variant_size<volatile T>; 90 template <class T> struct variant_size<const volatile T>; 91 92 template <class... Types> 93 struct variant_size<variant<Types...>>; 94 95 template <size_t I, class T> struct variant_alternative; // undefined 96 97 template <size_t I, class T> 98 using variant_alternative_t = typename variant_alternative<I, T>::type; 99 100 template <size_t I, class T> struct variant_alternative<I, const T>; 101 template <size_t I, class T> struct variant_alternative<I, volatile T>; 102 template <size_t I, class T> struct variant_alternative<I, const volatile T>; 103 104 template <size_t I, class... Types> 105 struct variant_alternative<I, variant<Types...>>; 106 107 inline constexpr size_t variant_npos = -1; 108 109 // 20.7.4, value access 110 template <class T, class... Types> 111 constexpr bool holds_alternative(const variant<Types...>&) noexcept; 112 113 template <size_t I, class... Types> 114 constexpr variant_alternative_t<I, variant<Types...>>& 115 get(variant<Types...>&); 116 117 template <size_t I, class... Types> 118 constexpr variant_alternative_t<I, variant<Types...>>&& 119 get(variant<Types...>&&); 120 121 template <size_t I, class... Types> 122 constexpr variant_alternative_t<I, variant<Types...>> const& 123 get(const variant<Types...>&); 124 125 template <size_t I, class... Types> 126 constexpr variant_alternative_t<I, variant<Types...>> const&& 127 get(const variant<Types...>&&); 128 129 template <class T, class... Types> 130 constexpr T& get(variant<Types...>&); 131 132 template <class T, class... Types> 133 constexpr T&& get(variant<Types...>&&); 134 135 template <class T, class... Types> 136 constexpr const T& get(const variant<Types...>&); 137 138 template <class T, class... Types> 139 constexpr const T&& get(const variant<Types...>&&); 140 141 template <size_t I, class... Types> 142 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>> 143 get_if(variant<Types...>*) noexcept; 144 145 template <size_t I, class... Types> 146 constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>> 147 get_if(const variant<Types...>*) noexcept; 148 149 template <class T, class... Types> 150 constexpr add_pointer_t<T> 151 get_if(variant<Types...>*) noexcept; 152 153 template <class T, class... Types> 154 constexpr add_pointer_t<const T> 155 get_if(const variant<Types...>*) noexcept; 156 157 // 20.7.5, relational operators 158 template <class... Types> 159 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&); 160 161 template <class... Types> 162 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&); 163 164 template <class... Types> 165 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&); 166 167 template <class... Types> 168 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&); 169 170 template <class... Types> 171 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&); 172 173 template <class... Types> 174 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&); 175 176 template <class... Types> requires (three_way_comparable<Types> && ...) 177 constexpr common_comparison_category_t<compare_three_way_result_t<Types>...> 178 operator<=>(const variant<Types...>&, const variant<Types...>&); // since C++20 179 180 // 20.7.6, visitation 181 template <class Visitor, class... Variants> 182 constexpr see below visit(Visitor&&, Variants&&...); 183 184 template <class R, class Visitor, class... Variants> 185 constexpr R visit(Visitor&&, Variants&&...); // since C++20 186 187 // 20.7.7, class monostate 188 struct monostate; 189 190 // 20.7.8, monostate relational operators 191 constexpr bool operator==(monostate, monostate) noexcept; 192 constexpr bool operator!=(monostate, monostate) noexcept; // until C++20 193 constexpr bool operator<(monostate, monostate) noexcept; // until C++20 194 constexpr bool operator>(monostate, monostate) noexcept; // until C++20 195 constexpr bool operator<=(monostate, monostate) noexcept; // until C++20 196 constexpr bool operator>=(monostate, monostate) noexcept; // until C++20 197 constexpr strong_ordering operator<=>(monostate, monostate) noexcept; // since C++20 198 199 // 20.7.9, specialized algorithms 200 template <class... Types> 201 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below); 202 203 // 20.7.10, class bad_variant_access 204 class bad_variant_access; 205 206 // 20.7.11, hash support 207 template <class T> struct hash; 208 template <class... Types> struct hash<variant<Types...>>; 209 template <> struct hash<monostate>; 210 211} // namespace std 212 213*/ 214 215#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) 216# include <__cxx03/__config> 217#else 218# include <__compare/common_comparison_category.h> 219# include <__compare/compare_three_way_result.h> 220# include <__compare/ordering.h> 221# include <__compare/three_way_comparable.h> 222# include <__config> 223# include <__exception/exception.h> 224# include <__functional/hash.h> 225# include <__functional/operations.h> 226# include <__functional/unary_function.h> 227# include <__fwd/variant.h> 228# include <__memory/addressof.h> 229# include <__memory/construct_at.h> 230# include <__tuple/find_index.h> 231# include <__tuple/sfinae_helpers.h> 232# include <__type_traits/add_cv_quals.h> 233# include <__type_traits/add_pointer.h> 234# include <__type_traits/common_type.h> 235# include <__type_traits/conditional.h> 236# include <__type_traits/conjunction.h> 237# include <__type_traits/decay.h> 238# include <__type_traits/dependent_type.h> 239# include <__type_traits/enable_if.h> 240# include <__type_traits/invoke.h> 241# include <__type_traits/is_array.h> 242# include <__type_traits/is_assignable.h> 243# include <__type_traits/is_constructible.h> 244# include <__type_traits/is_convertible.h> 245# include <__type_traits/is_core_convertible.h> 246# include <__type_traits/is_destructible.h> 247# include <__type_traits/is_nothrow_assignable.h> 248# include <__type_traits/is_nothrow_constructible.h> 249# include <__type_traits/is_reference.h> 250# include <__type_traits/is_replaceable.h> 251# include <__type_traits/is_same.h> 252# include <__type_traits/is_swappable.h> 253# include <__type_traits/is_trivially_assignable.h> 254# include <__type_traits/is_trivially_constructible.h> 255# include <__type_traits/is_trivially_destructible.h> 256# include <__type_traits/is_trivially_relocatable.h> 257# include <__type_traits/is_void.h> 258# include <__type_traits/remove_const.h> 259# include <__type_traits/remove_cvref.h> 260# include <__type_traits/remove_reference.h> 261# include <__type_traits/type_identity.h> 262# include <__type_traits/void_t.h> 263# include <__utility/declval.h> 264# include <__utility/forward.h> 265# include <__utility/forward_like.h> 266# include <__utility/in_place.h> 267# include <__utility/integer_sequence.h> 268# include <__utility/move.h> 269# include <__utility/swap.h> 270# include <__variant/monostate.h> 271# include <__verbose_abort> 272# include <initializer_list> 273# include <limits> 274# include <version> 275 276// standard-mandated includes 277 278// [variant.syn] 279# include <compare> 280 281# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 282# pragma GCC system_header 283# endif 284 285_LIBCPP_PUSH_MACROS 286# include <__undef_macros> 287 288_LIBCPP_BEGIN_UNVERSIONED_NAMESPACE_STD 289 290class _LIBCPP_EXPORTED_FROM_ABI bad_variant_access : public exception { 291public: 292 const char* what() const _NOEXCEPT override; 293}; 294 295_LIBCPP_END_UNVERSIONED_NAMESPACE_STD 296 297_LIBCPP_BEGIN_NAMESPACE_STD 298 299# if _LIBCPP_STD_VER >= 17 300 301// Light N-dimensional array of function pointers. Used in place of std::array to avoid 302// adding a dependency. 303template <class _Tp, size_t _Size> 304struct __farray { 305 static_assert(_Size > 0, "N-dimensional array should never be empty in std::visit"); 306 _Tp __buf_[_Size] = {}; 307 308 _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator[](size_t __n) const noexcept { return __buf_[__n]; } 309}; 310 311[[noreturn]] inline _LIBCPP_HIDE_FROM_ABI void __throw_bad_variant_access() { 312# if _LIBCPP_HAS_EXCEPTIONS 313 throw bad_variant_access(); 314# else 315 _LIBCPP_VERBOSE_ABORT("bad_variant_access was thrown in -fno-exceptions mode"); 316# endif 317} 318 319// variant_size 320template <class _Tp> 321struct variant_size<const _Tp> : variant_size<_Tp> {}; 322 323template <class _Tp> 324struct variant_size<volatile _Tp> : variant_size<_Tp> {}; 325 326template <class _Tp> 327struct variant_size<const volatile _Tp> : variant_size<_Tp> {}; 328 329template <class... _Types> 330struct variant_size<variant<_Types...>> : integral_constant<size_t, sizeof...(_Types)> {}; 331 332// variant_alternative 333template <size_t _Ip, class _Tp> 334struct variant_alternative<_Ip, const _Tp> : add_const<variant_alternative_t<_Ip, _Tp>> {}; 335 336template <size_t _Ip, class _Tp> 337struct variant_alternative<_Ip, volatile _Tp> : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 338 339template <size_t _Ip, class _Tp> 340struct variant_alternative<_Ip, const volatile _Tp> : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 341 342template <size_t _Ip, class... _Types> 343struct variant_alternative<_Ip, variant<_Types...>> { 344 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 345 using type _LIBCPP_NODEBUG = __type_pack_element<_Ip, _Types...>; 346}; 347 348template <size_t _NumAlternatives> 349_LIBCPP_HIDE_FROM_ABI constexpr auto __choose_index_type() { 350# ifdef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 351 if constexpr (_NumAlternatives < numeric_limits<unsigned char>::max()) 352 return static_cast<unsigned char>(0); 353 else if constexpr (_NumAlternatives < numeric_limits<unsigned short>::max()) 354 return static_cast<unsigned short>(0); 355 else 356# endif // _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 357 return static_cast<unsigned int>(0); 358} 359 360template <size_t _NumAlts> 361using __variant_index_t _LIBCPP_NODEBUG = decltype(std::__choose_index_type<_NumAlts>()); 362 363template <class _IndexType> 364constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); 365 366template <class... _Types> 367_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>& __as_variant(variant<_Types...>& __vs) noexcept { 368 return __vs; 369} 370 371template <class... _Types> 372_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>& __as_variant(const variant<_Types...>& __vs) noexcept { 373 return __vs; 374} 375 376template <class... _Types> 377_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>&& __as_variant(variant<_Types...>&& __vs) noexcept { 378 return std::move(__vs); 379} 380 381template <class... _Types> 382_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>&& __as_variant(const variant<_Types...>&& __vs) noexcept { 383 return std::move(__vs); 384} 385 386namespace __find_detail { 387 388template <class _Tp, class... _Types> 389_LIBCPP_HIDE_FROM_ABI constexpr size_t __find_index() { 390 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 391 size_t __result = __not_found; 392 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 393 if (__matches[__i]) { 394 if (__result != __not_found) { 395 return __ambiguous; 396 } 397 __result = __i; 398 } 399 } 400 return __result; 401} 402 403template <size_t _Index> 404struct __find_unambiguous_index_sfinae_impl : integral_constant<size_t, _Index> {}; 405 406template <> 407struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 408 409template <> 410struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 411 412template <class _Tp, class... _Types> 413struct __find_unambiguous_index_sfinae 414 : __find_unambiguous_index_sfinae_impl<__find_detail::__find_index<_Tp, _Types...>()> {}; 415 416} // namespace __find_detail 417 418namespace __variant_detail { 419 420struct __valueless_t {}; 421 422enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 423 424template <typename _Tp, template <typename> class _IsTriviallyAvailable, template <typename> class _IsAvailable> 425constexpr _Trait __trait = 426 _IsTriviallyAvailable<_Tp>::value ? _Trait::_TriviallyAvailable 427 : _IsAvailable<_Tp>::value 428 ? _Trait::_Available 429 : _Trait::_Unavailable; 430 431_LIBCPP_HIDE_FROM_ABI constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 432 _Trait __result = _Trait::_TriviallyAvailable; 433 for (_Trait __t : __traits) { 434 if (static_cast<int>(__t) > static_cast<int>(__result)) { 435 __result = __t; 436 } 437 } 438 return __result; 439} 440 441template <typename... _Types> 442struct __traits { 443 static constexpr _Trait __copy_constructible_trait = 444 __variant_detail::__common_trait({__trait<_Types, is_trivially_copy_constructible, is_copy_constructible>...}); 445 446 static constexpr _Trait __move_constructible_trait = 447 __variant_detail::__common_trait({__trait<_Types, is_trivially_move_constructible, is_move_constructible>...}); 448 449 static constexpr _Trait __copy_assignable_trait = __variant_detail::__common_trait( 450 {__copy_constructible_trait, __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 451 452 static constexpr _Trait __move_assignable_trait = __variant_detail::__common_trait( 453 {__move_constructible_trait, __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 454 455 static constexpr _Trait __destructible_trait = 456 __variant_detail::__common_trait({__trait<_Types, is_trivially_destructible, is_destructible>...}); 457}; 458 459namespace __access { 460 461struct __union { 462 template <class _Vp> 463 _LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 464 return std::forward<_Vp>(__v).__head; 465 } 466 467 template <class _Vp, size_t _Ip> 468 _LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 469 return __get_alt(std::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 470 } 471}; 472 473struct __base { 474 template <size_t _Ip, class _Vp> 475 _LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v) { 476 return __union::__get_alt(std::forward<_Vp>(__v).__data, in_place_index<_Ip>); 477 } 478}; 479 480struct __variant { 481 template <size_t _Ip, class _Vp> 482 _LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v) { 483 return __base::__get_alt<_Ip>(std::forward<_Vp>(__v).__impl_); 484 } 485}; 486 487} // namespace __access 488 489namespace __visitation { 490 491struct __base { 492 template <class _Visitor, class... _Vs> 493 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) 494 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 495 constexpr auto __fdiagonal = __make_fdiagonal<_Visitor&&, decltype(std::forward<_Vs>(__vs).__as_base())...>(); 496 return __fdiagonal[__index](std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__as_base()...); 497 } 498 499 template <class _Visitor, class... _Vs> 500 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, _Vs&&... __vs) { 501 constexpr auto __fmatrix = __make_fmatrix<_Visitor&&, decltype(std::forward<_Vs>(__vs).__as_base())...>(); 502 return __at(__fmatrix, __vs.index()...)(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__as_base()...); 503 } 504 505private: 506 template <class _Tp> 507 _LIBCPP_HIDE_FROM_ABI static constexpr const _Tp& __at(const _Tp& __elem) { 508 return __elem; 509 } 510 511 template <class _Tp, size_t _Np, typename... _Indices> 512 _LIBCPP_HIDE_FROM_ABI static constexpr auto&& 513 __at(const __farray<_Tp, _Np>& __elems, size_t __index, _Indices... __indices) { 514 return __at(__elems[__index], __indices...); 515 } 516 517 template <class _Fp, class... _Fs> 518 static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_visitor_return_type_check() { 519 static_assert( 520 __all<is_same_v<_Fp, _Fs>...>::value, "`std::visit` requires the visitor to have a single return type."); 521 } 522 523 template <class... _Fs> 524 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_farray(_Fs&&... __fs) { 525 __std_visit_visitor_return_type_check<__remove_cvref_t<_Fs>...>(); 526 using __result = __farray<common_type_t<__remove_cvref_t<_Fs>...>, sizeof...(_Fs)>; 527 return __result{{std::forward<_Fs>(__fs)...}}; 528 } 529 530 template <size_t... _Is> 531 struct __dispatcher { 532 template <class _Fp, class... _Vs> 533 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 534 return std::__invoke(static_cast<_Fp>(__f), __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 535 } 536 }; 537 538 template <class _Fp, class... _Vs, size_t... _Is> 539 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_dispatch(index_sequence<_Is...>) { 540 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 541 } 542 543 template <size_t _Ip, class _Fp, class... _Vs> 544 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal_impl() { 545 return __make_dispatch<_Fp, _Vs...>(index_sequence<((void)__type_identity<_Vs>{}, _Ip)...>{}); 546 } 547 548 template <class _Fp, class... _Vs, size_t... _Is> 549 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 550 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 551 } 552 553 template <class _Fp, class _Vp, class... _Vs> 554 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal() { 555 constexpr size_t __np = __remove_cvref_t<_Vp>::__size(); 556 static_assert(__all<(__np == __remove_cvref_t<_Vs>::__size())...>::value); 557 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<__np>{}); 558 } 559 560 template <class _Fp, class... _Vs, size_t... _Is> 561 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 562 return __make_dispatch<_Fp, _Vs...>(__is); 563 } 564 565 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 566 _LIBCPP_HIDE_FROM_ABI static constexpr auto 567 __make_fmatrix_impl(index_sequence<_Is...>, index_sequence<_Js...>, _Ls... __ls) { 568 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(index_sequence<_Is..., _Js>{}, __ls...)...); 569 } 570 571 template <class _Fp, class... _Vs> 572 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fmatrix() { 573 return __make_fmatrix_impl<_Fp, _Vs...>( 574 index_sequence<>{}, make_index_sequence<__remove_cvref_t<_Vs>::__size()>{}...); 575 } 576}; 577 578struct __variant { 579 template <class _Visitor, class... _Vs> 580 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) 581 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 582 return __base::__visit_alt_at(__index, std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__impl_...); 583 } 584 585 template <class _Visitor, class... _Vs> 586 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, _Vs&&... __vs) { 587 return __base::__visit_alt( 588 std::forward<_Visitor>(__visitor), std::__as_variant(std::forward<_Vs>(__vs)).__impl_...); 589 } 590 591 template <class _Visitor, class... _Vs> 592 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) 593 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 594 return __visit_alt_at(__index, __make_value_visitor(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...); 595 } 596 597 template <class _Visitor, class... _Vs> 598 _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, _Vs&&... __vs) { 599 return __visit_alt(__make_value_visitor(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...); 600 } 601 602# if _LIBCPP_STD_VER >= 20 603 template <class _Rp, class _Visitor, class... _Vs> 604 _LIBCPP_HIDE_FROM_ABI static constexpr _Rp __visit_value(_Visitor&& __visitor, _Vs&&... __vs) { 605 return __visit_alt(__make_value_visitor<_Rp>(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...); 606 } 607# endif 608 609private: 610 template <class _Visitor, class... _Values> 611 static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_exhaustive_visitor_check() { 612 static_assert(is_invocable_v<_Visitor, _Values...>, "`std::visit` requires the visitor to be exhaustive."); 613 } 614 615 template <class _Visitor> 616 struct __value_visitor { 617 template <class... _Alts> 618 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Alts&&... __alts) const { 619 __std_visit_exhaustive_visitor_check< _Visitor, decltype((std::forward<_Alts>(__alts).__value))...>(); 620 return std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...); 621 } 622 _Visitor&& __visitor; 623 }; 624 625# if _LIBCPP_STD_VER >= 20 626 template <class _Rp, class _Visitor> 627 struct __value_visitor_return_type { 628 template <class... _Alts> 629 _LIBCPP_HIDE_FROM_ABI constexpr _Rp operator()(_Alts&&... __alts) const { 630 __std_visit_exhaustive_visitor_check< _Visitor, decltype((std::forward<_Alts>(__alts).__value))...>(); 631 if constexpr (is_void_v<_Rp>) { 632 std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...); 633 } else { 634 return std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...); 635 } 636 } 637 638 _Visitor&& __visitor; 639 }; 640# endif 641 642 template <class _Visitor> 643 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 644 return __value_visitor<_Visitor>{std::forward<_Visitor>(__visitor)}; 645 } 646 647# if _LIBCPP_STD_VER >= 20 648 template <class _Rp, class _Visitor> 649 _LIBCPP_HIDE_FROM_ABI static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 650 return __value_visitor_return_type<_Rp, _Visitor>{std::forward<_Visitor>(__visitor)}; 651 } 652# endif 653}; 654 655} // namespace __visitation 656 657// Adding semi-colons in macro expansions helps clang-format to do a better job. 658// This macro is used to avoid compilation errors due to "stray" semi-colons. 659# define _LIBCPP_EAT_SEMICOLON static_assert(true, "") 660 661template <size_t _Index, class _Tp> 662struct __alt { 663 using __value_type _LIBCPP_NODEBUG = _Tp; 664 static constexpr size_t __index = _Index; 665 666 template <class... _Args> 667 _LIBCPP_HIDE_FROM_ABI explicit constexpr __alt(in_place_t, _Args&&... __args) 668 : __value(std::forward<_Args>(__args)...) {} 669 670 __value_type __value; 671}; 672 673template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 674union __union; 675 676template <_Trait _DestructibleTrait, size_t _Index> 677union __union<_DestructibleTrait, _Index> {}; 678 679# define _LIBCPP_VARIANT_UNION(destructible_trait, destructor_definition) \ 680 template <size_t _Index, class _Tp, class... _Types> \ 681 union __union<destructible_trait, _Index, _Tp, _Types...> { \ 682 public: \ 683 _LIBCPP_HIDE_FROM_ABI explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 684 \ 685 template <class... _Args> \ 686 _LIBCPP_HIDE_FROM_ABI explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 687 : __head(in_place, std::forward<_Args>(__args)...) {} \ 688 \ 689 template <size_t _Ip, class... _Args> \ 690 _LIBCPP_HIDE_FROM_ABI explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 691 : __tail(in_place_index<_Ip - 1>, std::forward<_Args>(__args)...) {} \ 692 \ 693 _LIBCPP_HIDE_FROM_ABI __union(const __union&) = default; \ 694 _LIBCPP_HIDE_FROM_ABI __union(__union&&) = default; \ 695 _LIBCPP_HIDE_FROM_ABI __union& operator=(const __union&) = default; \ 696 _LIBCPP_HIDE_FROM_ABI __union& operator=(__union&&) = default; \ 697 destructor_definition; \ 698 \ 699 private: \ 700 char __dummy; \ 701 __alt<_Index, _Tp> __head; \ 702 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 703 \ 704 friend struct __access::__union; \ 705 } 706 707_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, 708 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() = default); 709_LIBCPP_VARIANT_UNION( 710 _Trait::_Available, _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() {} _LIBCPP_EAT_SEMICOLON); 711_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() = delete); 712 713# undef _LIBCPP_VARIANT_UNION 714 715template <_Trait _DestructibleTrait, class... _Types> 716class __base { 717public: 718 using __index_t _LIBCPP_NODEBUG = __variant_index_t<sizeof...(_Types)>; 719 720 _LIBCPP_HIDE_FROM_ABI explicit constexpr __base(__valueless_t __tag) noexcept 721 : __data(__tag), __index(__variant_npos<__index_t>) {} 722 723 template <size_t _Ip, class... _Args> 724 _LIBCPP_HIDE_FROM_ABI explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 725 : __data(in_place_index<_Ip>, std::forward<_Args>(__args)...), __index(_Ip) {} 726 727 _LIBCPP_HIDE_FROM_ABI constexpr bool valueless_by_exception() const noexcept { return index() == variant_npos; } 728 729 _LIBCPP_HIDE_FROM_ABI constexpr size_t index() const noexcept { 730 return __index == __variant_npos<__index_t> ? variant_npos : __index; 731 } 732 733protected: 734 _LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() & { return *this; } 735 736 _LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() && { return std::move(*this); } 737 738 _LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() const& { return *this; } 739 740 _LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() const&& { return std::move(*this); } 741 742 _LIBCPP_HIDE_FROM_ABI static constexpr size_t __size() { return sizeof...(_Types); } 743 744 __union<_DestructibleTrait, 0, _Types...> __data; 745 __index_t __index; 746 747 friend struct __access::__base; 748 friend struct __visitation::__base; 749}; 750 751template <class _Traits, _Trait = _Traits::__destructible_trait> 752class __dtor; 753 754# define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor_definition, destroy) \ 755 template <class... _Types> \ 756 class __dtor<__traits<_Types...>, destructible_trait> : public __base<destructible_trait, _Types...> { \ 757 using __base_type _LIBCPP_NODEBUG = __base<destructible_trait, _Types...>; \ 758 using __index_t _LIBCPP_NODEBUG = typename __base_type::__index_t; \ 759 \ 760 public: \ 761 using __base_type::__base_type; \ 762 using __base_type::operator=; \ 763 _LIBCPP_HIDE_FROM_ABI __dtor(const __dtor&) = default; \ 764 _LIBCPP_HIDE_FROM_ABI __dtor(__dtor&&) = default; \ 765 _LIBCPP_HIDE_FROM_ABI __dtor& operator=(const __dtor&) = default; \ 766 _LIBCPP_HIDE_FROM_ABI __dtor& operator=(__dtor&&) = default; \ 767 destructor_definition; \ 768 \ 769 protected: \ 770 destroy; \ 771 } 772 773_LIBCPP_VARIANT_DESTRUCTOR( 774 _Trait::_TriviallyAvailable, 775 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() = default, 776 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept { 777 this->__index = __variant_npos<__index_t>; 778 } _LIBCPP_EAT_SEMICOLON); 779 780_LIBCPP_VARIANT_DESTRUCTOR( 781 _Trait::_Available, 782 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() { __destroy(); } _LIBCPP_EAT_SEMICOLON, 783 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept { 784 if (!this->valueless_by_exception()) { 785 __visitation::__base::__visit_alt( 786 [](auto& __alt) noexcept { 787 using __alt_type = __remove_cvref_t<decltype(__alt)>; 788 __alt.~__alt_type(); 789 }, 790 *this); 791 } 792 this->__index = __variant_npos<__index_t>; 793 } _LIBCPP_EAT_SEMICOLON); 794 795_LIBCPP_VARIANT_DESTRUCTOR(_Trait::_Unavailable, 796 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() = delete, 797 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept = delete); 798 799# undef _LIBCPP_VARIANT_DESTRUCTOR 800 801template <class _Traits> 802class __ctor : public __dtor<_Traits> { 803 using __base_type _LIBCPP_NODEBUG = __dtor<_Traits>; 804 805public: 806 using __base_type::__base_type; 807 using __base_type::operator=; 808 809protected: 810 template <class _Rhs> 811 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX20 void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) { 812 __lhs.__destroy(); 813 if (!__rhs.valueless_by_exception()) { 814 auto __rhs_index = __rhs.index(); 815 __visitation::__base::__visit_alt_at( 816 __rhs_index, 817 [&__lhs](auto&& __rhs_alt) { 818 std::__construct_at(std::addressof(__lhs.__data), 819 in_place_index<__decay_t<decltype(__rhs_alt)>::__index>, 820 std::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 821 }, 822 std::forward<_Rhs>(__rhs)); 823 __lhs.__index = __rhs_index; 824 } 825 } 826}; 827 828template <class _Traits, _Trait = _Traits::__move_constructible_trait> 829class __move_constructor; 830 831# define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, move_constructor_definition) \ 832 template <class... _Types> \ 833 class __move_constructor<__traits<_Types...>, move_constructible_trait> : public __ctor<__traits<_Types...>> { \ 834 using __base_type _LIBCPP_NODEBUG = __ctor<__traits<_Types...>>; \ 835 \ 836 public: \ 837 using __base_type::__base_type; \ 838 using __base_type::operator=; \ 839 \ 840 _LIBCPP_HIDE_FROM_ABI __move_constructor(const __move_constructor&) = default; \ 841 _LIBCPP_HIDE_FROM_ABI ~__move_constructor() = default; \ 842 _LIBCPP_HIDE_FROM_ABI __move_constructor& operator=(const __move_constructor&) = default; \ 843 _LIBCPP_HIDE_FROM_ABI __move_constructor& operator=(__move_constructor&&) = default; \ 844 move_constructor_definition; \ 845 } 846 847_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 848 _Trait::_TriviallyAvailable, 849 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&& __that) = default); 850 851_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 852 _Trait::_Available, 853 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&& __that) noexcept( 854 __all<is_nothrow_move_constructible_v<_Types>...>::value) : __move_constructor(__valueless_t{}) { 855 this->__generic_construct(*this, std::move(__that)); 856 } _LIBCPP_EAT_SEMICOLON); 857 858_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 859 _Trait::_Unavailable, 860 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&&) = delete); 861 862# undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 863 864template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 865class __copy_constructor; 866 867# define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, copy_constructor_definition) \ 868 template <class... _Types> \ 869 class __copy_constructor<__traits<_Types...>, copy_constructible_trait> \ 870 : public __move_constructor<__traits<_Types...>> { \ 871 using __base_type _LIBCPP_NODEBUG = __move_constructor<__traits<_Types...>>; \ 872 \ 873 public: \ 874 using __base_type::__base_type; \ 875 using __base_type::operator=; \ 876 \ 877 _LIBCPP_HIDE_FROM_ABI __copy_constructor(__copy_constructor&&) = default; \ 878 _LIBCPP_HIDE_FROM_ABI ~__copy_constructor() = default; \ 879 _LIBCPP_HIDE_FROM_ABI __copy_constructor& operator=(const __copy_constructor&) = default; \ 880 _LIBCPP_HIDE_FROM_ABI __copy_constructor& operator=(__copy_constructor&&) = default; \ 881 copy_constructor_definition; \ 882 } 883 884_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 885 _Trait::_TriviallyAvailable, 886 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor& __that) = default); 887 888_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 889 _Trait::_Available, 890 _LIBCPP_HIDE_FROM_ABI 891 _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor& __that) : __copy_constructor( 892 __valueless_t{}) { this->__generic_construct(*this, __that); } _LIBCPP_EAT_SEMICOLON); 893 894_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 895 _Trait::_Unavailable, 896 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor&) = delete); 897 898# undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 899 900template <class _Traits> 901class __assignment : public __copy_constructor<_Traits> { 902 using __base_type _LIBCPP_NODEBUG = __copy_constructor<_Traits>; 903 904public: 905 using __base_type::__base_type; 906 using __base_type::operator=; 907 908 template <size_t _Ip, class... _Args> 909 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto& __emplace(_Args&&... __args) { 910 this->__destroy(); 911 std::__construct_at(std::addressof(this->__data), in_place_index<_Ip>, std::forward<_Args>(__args)...); 912 this->__index = _Ip; 913 return __access::__base::__get_alt<_Ip>(*this).__value; 914 } 915 916protected: 917 template <size_t _Ip, class _Tp, class _Arg> 918 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 919 if (this->index() == _Ip) { 920 __a.__value = std::forward<_Arg>(__arg); 921 } else { 922 struct { 923 _LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 void operator()(true_type) const { 924 __this->__emplace<_Ip>(std::forward<_Arg>(__arg)); 925 } 926 _LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 void operator()(false_type) const { 927 __this->__emplace<_Ip>(_Tp(std::forward<_Arg>(__arg))); 928 } 929 __assignment* __this; 930 _Arg&& __arg; 931 } __impl{this, std::forward<_Arg>(__arg)}; 932 __impl(bool_constant < is_nothrow_constructible_v<_Tp, _Arg> || !is_nothrow_move_constructible_v < _Tp >> {}); 933 } 934 } 935 936 template <class _That> 937 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __generic_assign(_That&& __that) { 938 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 939 // do nothing. 940 } else if (__that.valueless_by_exception()) { 941 this->__destroy(); 942 } else { 943 __visitation::__base::__visit_alt_at( 944 __that.index(), 945 [this](auto& __this_alt, auto&& __that_alt) { 946 this->__assign_alt(__this_alt, std::forward<decltype(__that_alt)>(__that_alt).__value); 947 }, 948 *this, 949 std::forward<_That>(__that)); 950 } 951 } 952}; 953 954template <class _Traits, _Trait = _Traits::__move_assignable_trait> 955class __move_assignment; 956 957# define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, move_assignment_definition) \ 958 template <class... _Types> \ 959 class __move_assignment<__traits<_Types...>, move_assignable_trait> : public __assignment<__traits<_Types...>> { \ 960 using __base_type _LIBCPP_NODEBUG = __assignment<__traits<_Types...>>; \ 961 \ 962 public: \ 963 using __base_type::__base_type; \ 964 using __base_type::operator=; \ 965 \ 966 _LIBCPP_HIDE_FROM_ABI __move_assignment(const __move_assignment&) = default; \ 967 _LIBCPP_HIDE_FROM_ABI __move_assignment(__move_assignment&&) = default; \ 968 _LIBCPP_HIDE_FROM_ABI ~__move_assignment() = default; \ 969 _LIBCPP_HIDE_FROM_ABI __move_assignment& operator=(const __move_assignment&) = default; \ 970 move_assignment_definition; \ 971 } 972 973_LIBCPP_VARIANT_MOVE_ASSIGNMENT(_Trait::_TriviallyAvailable, 974 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment& operator=( 975 __move_assignment&& __that) = default); 976 977_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 978 _Trait::_Available, 979 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment& 980 operator=(__move_assignment&& __that) noexcept( 981 __all<(is_nothrow_move_constructible_v<_Types> && is_nothrow_move_assignable_v<_Types>)...>::value) { 982 this->__generic_assign(std::move(__that)); 983 return *this; 984 } _LIBCPP_EAT_SEMICOLON); 985 986_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 987 _Trait::_Unavailable, 988 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment& operator=(__move_assignment&&) = delete); 989 990# undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 991 992template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 993class __copy_assignment; 994 995# define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, copy_assignment_definition) \ 996 template <class... _Types> \ 997 class __copy_assignment<__traits<_Types...>, copy_assignable_trait> \ 998 : public __move_assignment<__traits<_Types...>> { \ 999 using __base_type _LIBCPP_NODEBUG = __move_assignment<__traits<_Types...>>; \ 1000 \ 1001 public: \ 1002 using __base_type::__base_type; \ 1003 using __base_type::operator=; \ 1004 \ 1005 _LIBCPP_HIDE_FROM_ABI __copy_assignment(const __copy_assignment&) = default; \ 1006 _LIBCPP_HIDE_FROM_ABI __copy_assignment(__copy_assignment&&) = default; \ 1007 _LIBCPP_HIDE_FROM_ABI ~__copy_assignment() = default; \ 1008 _LIBCPP_HIDE_FROM_ABI __copy_assignment& operator=(__copy_assignment&&) = default; \ 1009 copy_assignment_definition; \ 1010 } 1011 1012_LIBCPP_VARIANT_COPY_ASSIGNMENT(_Trait::_TriviallyAvailable, 1013 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment& operator=( 1014 const __copy_assignment& __that) = default); 1015 1016_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1017 _Trait::_Available, 1018 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment& 1019 operator=(const __copy_assignment& __that) { 1020 this->__generic_assign(__that); 1021 return *this; 1022 } _LIBCPP_EAT_SEMICOLON); 1023 1024_LIBCPP_VARIANT_COPY_ASSIGNMENT(_Trait::_Unavailable, 1025 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment& operator=( 1026 const __copy_assignment&) = delete); 1027 1028# undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1029 1030template <class... _Types> 1031class __impl : public __copy_assignment<__traits<_Types...>> { 1032 using __base_type _LIBCPP_NODEBUG = __copy_assignment<__traits<_Types...>>; 1033 1034public: 1035 using __base_type::__base_type; // get in_place_index_t constructor & friends 1036 _LIBCPP_HIDE_FROM_ABI __impl(__impl const&) = default; 1037 _LIBCPP_HIDE_FROM_ABI __impl(__impl&&) = default; 1038 _LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl const&) = default; 1039 _LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl&&) = default; 1040 1041 template <size_t _Ip, class _Arg> 1042 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __assign(_Arg&& __arg) { 1043 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), std::forward<_Arg>(__arg)); 1044 } 1045 1046 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__impl& __that) { 1047 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1048 // do nothing. 1049 } else if (this->index() == __that.index()) { 1050 __visitation::__base::__visit_alt_at( 1051 this->index(), 1052 [](auto& __this_alt, auto& __that_alt) { 1053 using std::swap; 1054 swap(__this_alt.__value, __that_alt.__value); 1055 }, 1056 *this, 1057 __that); 1058 } else { 1059 __impl* __lhs = this; 1060 __impl* __rhs = std::addressof(__that); 1061 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1062 std::swap(__lhs, __rhs); 1063 } 1064 __impl __tmp(std::move(*__rhs)); 1065# if _LIBCPP_HAS_EXCEPTIONS 1066 if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) { 1067 this->__generic_construct(*__rhs, std::move(*__lhs)); 1068 } else { 1069 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1070 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1071 // into `__rhs` and provide the strong exception safety guarantee. 1072 try { 1073 this->__generic_construct(*__rhs, std::move(*__lhs)); 1074 } catch (...) { 1075 if (__tmp.__move_nothrow()) { 1076 this->__generic_construct(*__rhs, std::move(__tmp)); 1077 } 1078 throw; 1079 } 1080 } 1081# else 1082 // this isn't consolidated with the `if constexpr` branch above due to 1083 // `throw` being ill-formed with exceptions disabled even when discarded. 1084 this->__generic_construct(*__rhs, std::move(*__lhs)); 1085# endif 1086 this->__generic_construct(*__lhs, std::move(__tmp)); 1087 } 1088 } 1089 1090private: 1091 constexpr inline _LIBCPP_HIDE_FROM_ABI bool __move_nothrow() const { 1092 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1093 return this->valueless_by_exception() || __results[this->index()]; 1094 } 1095}; 1096 1097struct __no_narrowing_check { 1098 template <class _Dest, class _Source> 1099 using _Apply _LIBCPP_NODEBUG = __type_identity<_Dest>; 1100}; 1101 1102struct __narrowing_check { 1103 template <class _Dest> 1104 static auto __test_impl(_Dest (&&)[1]) -> __type_identity<_Dest>; 1105 template <class _Dest, class _Source> 1106 using _Apply _LIBCPP_NODEBUG = decltype(__test_impl<_Dest>({std::declval<_Source>()})); 1107}; 1108 1109template <class _Dest, class _Source> 1110using __check_for_narrowing _LIBCPP_NODEBUG = 1111 typename _If< is_arithmetic<_Dest>::value, __narrowing_check, __no_narrowing_check >::template _Apply<_Dest, 1112 _Source>; 1113 1114template <class _Tp, size_t _Idx> 1115struct __overload { 1116 template <class _Up> 1117 auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>; 1118}; 1119 1120template <class... _Bases> 1121struct __all_overloads : _Bases... { 1122 void operator()() const; 1123 using _Bases::operator()...; 1124}; 1125 1126template <class _IdxSeq> 1127struct __make_overloads_imp; 1128 1129template <size_t... _Idx> 1130struct __make_overloads_imp<__tuple_indices<_Idx...> > { 1131 template <class... _Types> 1132 using _Apply _LIBCPP_NODEBUG = __all_overloads<__overload<_Types, _Idx>...>; 1133}; 1134 1135template <class... _Types> 1136using _MakeOverloads _LIBCPP_NODEBUG = 1137 typename __make_overloads_imp< __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>; 1138 1139template <class _Tp, class... _Types> 1140using __best_match_t _LIBCPP_NODEBUG = typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type; 1141 1142} // namespace __variant_detail 1143 1144template <class _Visitor, class... _Vs, typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...>> 1145_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs); 1146 1147# if _LIBCPP_STD_VER >= 20 1148template <class _Rp, 1149 class _Visitor, 1150 class... _Vs, 1151 typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...>> 1152_LIBCPP_HIDE_FROM_ABI constexpr _Rp visit(_Visitor&& __visitor, _Vs&&... __vs); 1153# endif 1154 1155template <class... _Types> 1156class _LIBCPP_DECLSPEC_EMPTY_BASES _LIBCPP_NO_SPECIALIZATIONS variant 1157 : private __sfinae_ctor_base< __all<is_copy_constructible_v<_Types>...>::value, 1158 __all<is_move_constructible_v<_Types>...>::value>, 1159 private __sfinae_assign_base< 1160 __all<(is_copy_constructible_v<_Types> && is_copy_assignable_v<_Types>)...>::value, 1161 __all<(is_move_constructible_v<_Types> && is_move_assignable_v<_Types>)...>::value> { 1162 static_assert(0 < sizeof...(_Types), "variant must consist of at least one alternative."); 1163 1164 static_assert(__all<!is_array_v<_Types>...>::value, "variant can not have an array type as an alternative."); 1165 1166 static_assert(__all<!is_reference_v<_Types>...>::value, "variant can not have a reference type as an alternative."); 1167 1168 static_assert(__all<!is_void_v<_Types>...>::value, "variant can not have a void type as an alternative."); 1169 1170 using __first_type _LIBCPP_NODEBUG = variant_alternative_t<0, variant>; 1171 1172public: 1173 using __trivially_relocatable _LIBCPP_NODEBUG = 1174 conditional_t<_And<__libcpp_is_trivially_relocatable<_Types>...>::value, variant, void>; 1175 using __replaceable _LIBCPP_NODEBUG = conditional_t<_And<__is_replaceable<_Types>...>::value, variant, void>; 1176 1177 template <bool _Dummy = true, 1178 enable_if_t<__dependent_type<is_default_constructible<__first_type>, _Dummy>::value, int> = 0> 1179 _LIBCPP_HIDE_FROM_ABI constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1180 : __impl_(in_place_index<0>) {} 1181 1182 _LIBCPP_HIDE_FROM_ABI constexpr variant(const variant&) = default; 1183 _LIBCPP_HIDE_FROM_ABI constexpr variant(variant&&) = default; 1184 1185 template < class _Arg, 1186 enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0, 1187 enable_if_t<!__is_inplace_type<__remove_cvref_t<_Arg>>::value, int> = 0, 1188 enable_if_t<!__is_inplace_index<__remove_cvref_t<_Arg>>::value, int> = 0, 1189 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1190 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1191 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1192 _LIBCPP_HIDE_FROM_ABI constexpr variant(_Arg&& __arg) noexcept(is_nothrow_constructible_v<_Tp, _Arg>) 1193 : __impl_(in_place_index<_Ip>, std::forward<_Arg>(__arg)) {} 1194 1195 template <size_t _Ip, 1196 class... _Args, 1197 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1198 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1199 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1200 _LIBCPP_HIDE_FROM_ABI explicit constexpr variant(in_place_index_t<_Ip>, _Args&&... __args) noexcept( 1201 is_nothrow_constructible_v<_Tp, _Args...>) 1202 : __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {} 1203 1204 template < size_t _Ip, 1205 class _Up, 1206 class... _Args, 1207 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1208 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1209 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> 1210 _LIBCPP_HIDE_FROM_ABI explicit constexpr variant( 1211 in_place_index_t<_Ip>, 1212 initializer_list<_Up> __il, 1213 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1214 : __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {} 1215 1216 template < class _Tp, 1217 class... _Args, 1218 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1219 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1220 _LIBCPP_HIDE_FROM_ABI explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1221 is_nothrow_constructible_v<_Tp, _Args...>) 1222 : __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {} 1223 1224 template < class _Tp, 1225 class _Up, 1226 class... _Args, 1227 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1228 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> 1229 _LIBCPP_HIDE_FROM_ABI explicit constexpr variant( 1230 in_place_type_t<_Tp>, 1231 initializer_list<_Up> __il, 1232 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1233 : __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {} 1234 1235 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~variant() = default; 1236 1237 _LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(const variant&) = default; 1238 _LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(variant&&) = default; 1239 1240 template < class _Arg, 1241 enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0, 1242 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1243 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1244 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, int> = 0> 1245 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 variant& 1246 operator=(_Arg&& __arg) noexcept(is_nothrow_assignable_v<_Tp&, _Arg> && is_nothrow_constructible_v<_Tp, _Arg>) { 1247 __impl_.template __assign<_Ip>(std::forward<_Arg>(__arg)); 1248 return *this; 1249 } 1250 1251 template < size_t _Ip, 1252 class... _Args, 1253 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1254 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1255 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1256 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(_Args&&... __args) { 1257 return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...); 1258 } 1259 1260 template < size_t _Ip, 1261 class _Up, 1262 class... _Args, 1263 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1264 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1265 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> 1266 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1267 return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...); 1268 } 1269 1270 template < class _Tp, 1271 class... _Args, 1272 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1273 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1274 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(_Args&&... __args) { 1275 return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...); 1276 } 1277 1278 template < class _Tp, 1279 class _Up, 1280 class... _Args, 1281 size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1282 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0> 1283 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1284 return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...); 1285 } 1286 1287 _LIBCPP_HIDE_FROM_ABI constexpr bool valueless_by_exception() const noexcept { 1288 return __impl_.valueless_by_exception(); 1289 } 1290 1291 _LIBCPP_HIDE_FROM_ABI constexpr size_t index() const noexcept { return __impl_.index(); } 1292 1293 template < bool _Dummy = true, 1294 enable_if_t< __all<(__dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1295 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1296 int> = 0> 1297 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(variant& __that) noexcept( 1298 __all<(is_nothrow_move_constructible_v<_Types> && is_nothrow_swappable_v<_Types>)...>::value) { 1299 __impl_.__swap(__that.__impl_); 1300 } 1301 1302# if _LIBCPP_STD_VER >= 26 && _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 1303 // Helper class to implement [variant.visit]/10 1304 // Constraints: The call to visit does not use an explicit template-argument-list 1305 // that begins with a type template-argument. 1306 struct __variant_visit_barrier_tag { 1307 _LIBCPP_HIDE_FROM_ABI explicit __variant_visit_barrier_tag() = default; 1308 }; 1309 1310 template <__variant_visit_barrier_tag = __variant_visit_barrier_tag{}, class _Self, class _Visitor> 1311 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) visit(this _Self&& __self, _Visitor&& __visitor) { 1312 return std::visit(std::forward<_Visitor>(__visitor), std::__forward_as<_Self, variant>(__self)); 1313 } 1314 1315 template <class _Rp, class _Self, class _Visitor> 1316 _LIBCPP_HIDE_FROM_ABI constexpr _Rp visit(this _Self&& __self, _Visitor&& __visitor) { 1317 return std::visit<_Rp>(std::forward<_Visitor>(__visitor), std::__forward_as<_Self, variant>(__self)); 1318 } 1319# endif 1320 1321private: 1322 __variant_detail::__impl<_Types...> __impl_; 1323 1324 friend struct __variant_detail::__access::__variant; 1325 friend struct __variant_detail::__visitation::__variant; 1326}; 1327 1328template <size_t _Ip, class... _Types> 1329_LIBCPP_HIDE_FROM_ABI constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1330 return __v.index() == _Ip; 1331} 1332 1333template <class _Tp, class... _Types> 1334_LIBCPP_HIDE_FROM_ABI constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1335 return std::__holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1336} 1337 1338template <size_t _Ip, class _Vp> 1339_LIBCPP_HIDE_FROM_ABI constexpr auto&& __generic_get(_Vp&& __v) { 1340 using __variant_detail::__access::__variant; 1341 if (!std::__holds_alternative<_Ip>(__v)) { 1342 std::__throw_bad_variant_access(); 1343 } 1344 return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value; 1345} 1346 1347template <size_t _Ip, class... _Types> 1348_LIBCPP_HIDE_FROM_ABI constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(variant<_Types...>& __v) { 1349 static_assert(_Ip < sizeof...(_Types)); 1350 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1351 return std::__generic_get<_Ip>(__v); 1352} 1353 1354template <size_t _Ip, class... _Types> 1355_LIBCPP_HIDE_FROM_ABI constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(variant<_Types...>&& __v) { 1356 static_assert(_Ip < sizeof...(_Types)); 1357 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1358 return std::__generic_get<_Ip>(std::move(__v)); 1359} 1360 1361template <size_t _Ip, class... _Types> 1362_LIBCPP_HIDE_FROM_ABI constexpr const variant_alternative_t<_Ip, variant<_Types...>>& 1363get(const variant<_Types...>& __v) { 1364 static_assert(_Ip < sizeof...(_Types)); 1365 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1366 return std::__generic_get<_Ip>(__v); 1367} 1368 1369template <size_t _Ip, class... _Types> 1370_LIBCPP_HIDE_FROM_ABI constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& 1371get(const variant<_Types...>&& __v) { 1372 static_assert(_Ip < sizeof...(_Types)); 1373 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1374 return std::__generic_get<_Ip>(std::move(__v)); 1375} 1376 1377template <class _Tp, class... _Types> 1378_LIBCPP_HIDE_FROM_ABI constexpr _Tp& get(variant<_Types...>& __v) { 1379 static_assert(!is_void_v<_Tp>); 1380 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1381} 1382 1383template <class _Tp, class... _Types> 1384_LIBCPP_HIDE_FROM_ABI constexpr _Tp&& get(variant<_Types...>&& __v) { 1385 static_assert(!is_void_v<_Tp>); 1386 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(std::move(__v)); 1387} 1388 1389template <class _Tp, class... _Types> 1390_LIBCPP_HIDE_FROM_ABI constexpr const _Tp& get(const variant<_Types...>& __v) { 1391 static_assert(!is_void_v<_Tp>); 1392 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1393} 1394 1395template <class _Tp, class... _Types> 1396_LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1397 static_assert(!is_void_v<_Tp>); 1398 return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(std::move(__v)); 1399} 1400 1401template <size_t _Ip, class _Vp> 1402_LIBCPP_HIDE_FROM_ABI constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1403 using __variant_detail::__access::__variant; 1404 return __v && std::__holds_alternative<_Ip>(*__v) ? std::addressof(__variant::__get_alt<_Ip>(*__v).__value) : nullptr; 1405} 1406 1407template <size_t _Ip, class... _Types> 1408_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1409get_if(variant<_Types...>* __v) noexcept { 1410 static_assert(_Ip < sizeof...(_Types)); 1411 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1412 return std::__generic_get_if<_Ip>(__v); 1413} 1414 1415template <size_t _Ip, class... _Types> 1416_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1417get_if(const variant<_Types...>* __v) noexcept { 1418 static_assert(_Ip < sizeof...(_Types)); 1419 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1420 return std::__generic_get_if<_Ip>(__v); 1421} 1422 1423template <class _Tp, class... _Types> 1424_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> get_if(variant<_Types...>* __v) noexcept { 1425 static_assert(!is_void_v<_Tp>); 1426 return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1427} 1428 1429template <class _Tp, class... _Types> 1430_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<const _Tp> get_if(const variant<_Types...>* __v) noexcept { 1431 static_assert(!is_void_v<_Tp>); 1432 return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1433} 1434 1435template <class _Operator> 1436struct __convert_to_bool { 1437 template <class _T1, class _T2> 1438 _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_T1&& __t1, _T2&& __t2) const { 1439 static_assert(is_convertible<decltype(_Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2))), bool>::value, 1440 "the relational operator does not return a type which is implicitly convertible to bool"); 1441 return _Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2)); 1442 } 1443}; 1444 1445template <class... _Types> 1446# if _LIBCPP_STD_VER >= 26 1447 requires(requires(const _Types& __t) { 1448 { __t == __t } -> __core_convertible_to<bool>; 1449 } && ...) 1450# endif 1451_LIBCPP_HIDE_FROM_ABI constexpr bool operator==(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1452 using __variant_detail::__visitation::__variant; 1453 if (__lhs.index() != __rhs.index()) 1454 return false; 1455 if (__lhs.valueless_by_exception()) 1456 return true; 1457 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs); 1458} 1459 1460# if _LIBCPP_STD_VER >= 20 1461 1462template <class... _Types> 1463 requires(three_way_comparable<_Types> && ...) 1464_LIBCPP_HIDE_FROM_ABI constexpr common_comparison_category_t<compare_three_way_result_t<_Types>...> 1465operator<=>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1466 using __variant_detail::__visitation::__variant; 1467 using __result_t = common_comparison_category_t<compare_three_way_result_t<_Types>...>; 1468 if (__lhs.valueless_by_exception() && __rhs.valueless_by_exception()) 1469 return strong_ordering::equal; 1470 if (__lhs.valueless_by_exception()) 1471 return strong_ordering::less; 1472 if (__rhs.valueless_by_exception()) 1473 return strong_ordering::greater; 1474 if (auto __c = __lhs.index() <=> __rhs.index(); __c != 0) 1475 return __c; 1476 auto __three_way = []<class _Type>(const _Type& __v, const _Type& __w) -> __result_t { return __v <=> __w; }; 1477 return __variant::__visit_value_at(__lhs.index(), __three_way, __lhs, __rhs); 1478} 1479 1480# endif // _LIBCPP_STD_VER >= 20 1481 1482template <class... _Types> 1483# if _LIBCPP_STD_VER >= 26 1484 requires(requires(const _Types& __t) { 1485 { __t != __t } -> __core_convertible_to<bool>; 1486 } && ...) 1487# endif 1488_LIBCPP_HIDE_FROM_ABI constexpr bool operator!=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1489 using __variant_detail::__visitation::__variant; 1490 if (__lhs.index() != __rhs.index()) 1491 return true; 1492 if (__lhs.valueless_by_exception()) 1493 return false; 1494 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs); 1495} 1496 1497template <class... _Types> 1498# if _LIBCPP_STD_VER >= 26 1499 requires(requires(const _Types& __t) { 1500 { __t < __t } -> __core_convertible_to<bool>; 1501 } && ...) 1502# endif 1503_LIBCPP_HIDE_FROM_ABI constexpr bool operator<(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1504 using __variant_detail::__visitation::__variant; 1505 if (__rhs.valueless_by_exception()) 1506 return false; 1507 if (__lhs.valueless_by_exception()) 1508 return true; 1509 if (__lhs.index() < __rhs.index()) 1510 return true; 1511 if (__lhs.index() > __rhs.index()) 1512 return false; 1513 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs); 1514} 1515 1516template <class... _Types> 1517# if _LIBCPP_STD_VER >= 26 1518 requires(requires(const _Types& __t) { 1519 { __t > __t } -> __core_convertible_to<bool>; 1520 } && ...) 1521# endif 1522_LIBCPP_HIDE_FROM_ABI constexpr bool operator>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1523 using __variant_detail::__visitation::__variant; 1524 if (__lhs.valueless_by_exception()) 1525 return false; 1526 if (__rhs.valueless_by_exception()) 1527 return true; 1528 if (__lhs.index() > __rhs.index()) 1529 return true; 1530 if (__lhs.index() < __rhs.index()) 1531 return false; 1532 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs); 1533} 1534 1535template <class... _Types> 1536# if _LIBCPP_STD_VER >= 26 1537 requires(requires(const _Types& __t) { 1538 { __t <= __t } -> __core_convertible_to<bool>; 1539 } && ...) 1540# endif 1541_LIBCPP_HIDE_FROM_ABI constexpr bool operator<=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1542 using __variant_detail::__visitation::__variant; 1543 if (__lhs.valueless_by_exception()) 1544 return true; 1545 if (__rhs.valueless_by_exception()) 1546 return false; 1547 if (__lhs.index() < __rhs.index()) 1548 return true; 1549 if (__lhs.index() > __rhs.index()) 1550 return false; 1551 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs); 1552} 1553 1554template <class... _Types> 1555# if _LIBCPP_STD_VER >= 26 1556 requires(requires(const _Types& __t) { 1557 { __t >= __t } -> __core_convertible_to<bool>; 1558 } && ...) 1559# endif 1560_LIBCPP_HIDE_FROM_ABI constexpr bool operator>=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) { 1561 using __variant_detail::__visitation::__variant; 1562 if (__rhs.valueless_by_exception()) 1563 return true; 1564 if (__lhs.valueless_by_exception()) 1565 return false; 1566 if (__lhs.index() > __rhs.index()) 1567 return true; 1568 if (__lhs.index() < __rhs.index()) 1569 return false; 1570 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs); 1571} 1572 1573template <class... _Vs> 1574_LIBCPP_HIDE_FROM_ABI constexpr void __throw_if_valueless(_Vs&&... __vs) { 1575 const bool __valueless = (... || std::__as_variant(__vs).valueless_by_exception()); 1576 if (__valueless) { 1577 std::__throw_bad_variant_access(); 1578 } 1579} 1580 1581template < class _Visitor, class... _Vs, typename> 1582_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1583 using __variant_detail::__visitation::__variant; 1584 std::__throw_if_valueless(std::forward<_Vs>(__vs)...); 1585 return __variant::__visit_value(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs)...); 1586} 1587 1588# if _LIBCPP_STD_VER >= 20 1589template < class _Rp, class _Visitor, class... _Vs, typename> 1590_LIBCPP_HIDE_FROM_ABI constexpr _Rp visit(_Visitor&& __visitor, _Vs&&... __vs) { 1591 using __variant_detail::__visitation::__variant; 1592 std::__throw_if_valueless(std::forward<_Vs>(__vs)...); 1593 return __variant::__visit_value<_Rp>(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs)...); 1594} 1595# endif 1596 1597template <class... _Types> 1598_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto 1599swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1600 -> decltype(__lhs.swap(__rhs)) { 1601 return __lhs.swap(__rhs); 1602} 1603 1604template <class... _Types> 1605struct hash< __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1606# if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_BINDER_TYPEDEFS) 1607 using argument_type _LIBCPP_DEPRECATED_IN_CXX17 = variant<_Types...>; 1608 using result_type _LIBCPP_DEPRECATED_IN_CXX17 = size_t; 1609# endif 1610 1611 _LIBCPP_HIDE_FROM_ABI size_t operator()(const variant<_Types...>& __v) const { 1612 using __variant_detail::__visitation::__variant; 1613 size_t __res = 1614 __v.valueless_by_exception() 1615 ? 299792458 // Random value chosen by the universe upon creation 1616 : __variant::__visit_alt( 1617 [](const auto& __alt) { 1618 using __alt_type = __remove_cvref_t<decltype(__alt)>; 1619 using __value_type = remove_const_t< typename __alt_type::__value_type>; 1620 return hash<__value_type>{}(__alt.__value); 1621 }, 1622 __v); 1623 return std::__hash_combine(__res, hash<size_t>{}(__v.index())); 1624 } 1625}; 1626 1627// __unchecked_get is the same as std::get, except, it is UB to use it with the wrong 1628// type whereas std::get will throw or returning nullptr. This makes it faster than 1629// std::get. 1630template <size_t _Ip, class _Vp> 1631_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(_Vp&& __v) noexcept { 1632 using __variant_detail::__access::__variant; 1633 return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value; 1634} 1635 1636template <class _Tp, class... _Types> 1637_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(const variant<_Types...>& __v) noexcept { 1638 return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1639} 1640 1641template <class _Tp, class... _Types> 1642_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(variant<_Types...>& __v) noexcept { 1643 return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1644} 1645 1646# endif // _LIBCPP_STD_VER >= 17 1647 1648_LIBCPP_END_NAMESPACE_STD 1649 1650_LIBCPP_POP_MACROS 1651 1652# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20 1653# include <cstddef> 1654# include <exception> 1655# include <tuple> 1656# include <type_traits> 1657# include <typeinfo> 1658# include <utility> 1659# endif 1660#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS) 1661 1662#endif // _LIBCPP_VARIANT 1663