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