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