1 // -*- C++ -*- 2 //===------------------------------ variant -------------------------------===// 3 // 4 // The LLVM Compiler Infrastructure 5 // 6 // This file is dual licensed under the MIT and the University of Illinois Open 7 // Source Licenses. See LICENSE.TXT for details. 8 // 9 //===----------------------------------------------------------------------===// 10 11 #ifndef _LIBCPP_VARIANT 12 #define _LIBCPP_VARIANT 13 14 /* 15 variant synopsis 16 17 namespace std { 18 19 // 20.7.2, class template variant 20 template <class... Types> 21 class variant { 22 public: 23 24 // 20.7.2.1, constructors 25 constexpr variant() noexcept(see below); 26 variant(const variant&); 27 variant(variant&&) noexcept(see below); 28 29 template <class T> constexpr variant(T&&) noexcept(see below); 30 31 template <class T, class... Args> 32 constexpr explicit variant(in_place_type_t<T>, Args&&...); 33 34 template <class T, class U, class... Args> 35 constexpr explicit variant( 36 in_place_type_t<T>, initializer_list<U>, Args&&...); 37 38 template <size_t I, class... Args> 39 constexpr explicit variant(in_place_index_t<I>, Args&&...); 40 41 template <size_t I, class U, class... Args> 42 constexpr explicit variant( 43 in_place_index_t<I>, initializer_list<U>, Args&&...); 44 45 // 20.7.2.2, destructor 46 ~variant(); 47 48 // 20.7.2.3, assignment 49 variant& operator=(const variant&); 50 variant& operator=(variant&&) noexcept(see below); 51 52 template <class T> variant& operator=(T&&) noexcept(see below); 53 54 // 20.7.2.4, modifiers 55 template <class T, class... Args> 56 T& emplace(Args&&...); 57 58 template <class T, class U, class... Args> 59 T& emplace(initializer_list<U>, Args&&...); 60 61 template <size_t I, class... Args> 62 variant_alternative_t<I, variant>& emplace(Args&&...); 63 64 template <size_t I, class U, class... Args> 65 variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...); 66 67 // 20.7.2.5, value status 68 constexpr bool valueless_by_exception() const noexcept; 69 constexpr size_t index() const noexcept; 70 71 // 20.7.2.6, swap 72 void swap(variant&) noexcept(see below); 73 }; 74 75 // 20.7.3, variant helper classes 76 template <class T> struct variant_size; // undefined 77 78 template <class T> 79 constexpr size_t variant_size_v = variant_size<T>::value; 80 81 template <class T> struct variant_size<const T>; 82 template <class T> struct variant_size<volatile T>; 83 template <class T> struct variant_size<const volatile T>; 84 85 template <class... Types> 86 struct variant_size<variant<Types...>>; 87 88 template <size_t I, class T> struct variant_alternative; // undefined 89 90 template <size_t I, class T> 91 using variant_alternative_t = typename variant_alternative<I, T>::type; 92 93 template <size_t I, class T> struct variant_alternative<I, const T>; 94 template <size_t I, class T> struct variant_alternative<I, volatile T>; 95 template <size_t I, class T> struct variant_alternative<I, const volatile T>; 96 97 template <size_t I, class... Types> 98 struct variant_alternative<I, variant<Types...>>; 99 100 constexpr size_t variant_npos = -1; 101 102 // 20.7.4, value access 103 template <class T, class... Types> 104 constexpr bool holds_alternative(const variant<Types...>&) noexcept; 105 106 template <size_t I, class... Types> 107 constexpr variant_alternative_t<I, variant<Types...>>& 108 get(variant<Types...>&); 109 110 template <size_t I, class... Types> 111 constexpr variant_alternative_t<I, variant<Types...>>&& 112 get(variant<Types...>&&); 113 114 template <size_t I, class... Types> 115 constexpr variant_alternative_t<I, variant<Types...>> const& 116 get(const variant<Types...>&); 117 118 template <size_t I, class... Types> 119 constexpr variant_alternative_t<I, variant<Types...>> const&& 120 get(const variant<Types...>&&); 121 122 template <class T, class... Types> 123 constexpr T& get(variant<Types...>&); 124 125 template <class T, class... Types> 126 constexpr T&& get(variant<Types...>&&); 127 128 template <class T, class... Types> 129 constexpr const T& get(const variant<Types...>&); 130 131 template <class T, class... Types> 132 constexpr const T&& get(const variant<Types...>&&); 133 134 template <size_t I, class... Types> 135 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>> 136 get_if(variant<Types...>*) noexcept; 137 138 template <size_t I, class... Types> 139 constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>> 140 get_if(const variant<Types...>*) noexcept; 141 142 template <class T, class... Types> 143 constexpr add_pointer_t<T> 144 get_if(variant<Types...>*) noexcept; 145 146 template <class T, class... Types> 147 constexpr add_pointer_t<const T> 148 get_if(const variant<Types...>*) noexcept; 149 150 // 20.7.5, relational operators 151 template <class... Types> 152 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&); 153 154 template <class... Types> 155 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&); 156 157 template <class... Types> 158 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&); 159 160 template <class... Types> 161 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&); 162 163 template <class... Types> 164 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&); 165 166 template <class... Types> 167 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&); 168 169 // 20.7.6, visitation 170 template <class Visitor, class... Variants> 171 constexpr see below visit(Visitor&&, Variants&&...); 172 173 // 20.7.7, class monostate 174 struct monostate; 175 176 // 20.7.8, monostate relational operators 177 constexpr bool operator<(monostate, monostate) noexcept; 178 constexpr bool operator>(monostate, monostate) noexcept; 179 constexpr bool operator<=(monostate, monostate) noexcept; 180 constexpr bool operator>=(monostate, monostate) noexcept; 181 constexpr bool operator==(monostate, monostate) noexcept; 182 constexpr bool operator!=(monostate, monostate) noexcept; 183 184 // 20.7.9, specialized algorithms 185 template <class... Types> 186 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below); 187 188 // 20.7.10, class bad_variant_access 189 class bad_variant_access; 190 191 // 20.7.11, hash support 192 template <class T> struct hash; 193 template <class... Types> struct hash<variant<Types...>>; 194 template <> struct hash<monostate>; 195 196 } // namespace std 197 198 */ 199 200 #include <__config> 201 #include <__tuple> 202 #include <array> 203 #include <exception> 204 #include <functional> 205 #include <initializer_list> 206 #include <new> 207 #include <tuple> 208 #include <type_traits> 209 #include <utility> 210 211 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 212 #pragma GCC system_header 213 #endif 214 215 namespace std { // explicitly not using versioning namespace 216 217 class _LIBCPP_EXCEPTION_ABI bad_variant_access : public exception { 218 public: 219 virtual const char* what() const _NOEXCEPT; 220 }; 221 222 } // namespace std 223 224 _LIBCPP_BEGIN_NAMESPACE_STD 225 226 #if _LIBCPP_STD_VER > 14 227 228 _LIBCPP_NORETURN 229 inline _LIBCPP_INLINE_VISIBILITY 230 void __throw_bad_variant_access() { 231 #ifndef _LIBCPP_NO_EXCEPTIONS 232 throw bad_variant_access(); 233 #else 234 _VSTD::abort(); 235 #endif 236 } 237 238 template <class... _Types> 239 class _LIBCPP_TEMPLATE_VIS variant; 240 241 template <class _Tp> 242 struct _LIBCPP_TEMPLATE_VIS variant_size; 243 244 template <class _Tp> 245 constexpr size_t variant_size_v = variant_size<_Tp>::value; 246 247 template <class _Tp> 248 struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {}; 249 250 template <class _Tp> 251 struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {}; 252 253 template <class _Tp> 254 struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> 255 : variant_size<_Tp> {}; 256 257 template <class... _Types> 258 struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> 259 : integral_constant<size_t, sizeof...(_Types)> {}; 260 261 template <size_t _Ip, class _Tp> 262 struct _LIBCPP_TEMPLATE_VIS variant_alternative; 263 264 template <size_t _Ip, class _Tp> 265 using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type; 266 267 template <size_t _Ip, class _Tp> 268 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> 269 : add_const<variant_alternative_t<_Ip, _Tp>> {}; 270 271 template <size_t _Ip, class _Tp> 272 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> 273 : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 274 275 template <size_t _Ip, class _Tp> 276 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> 277 : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 278 279 template <size_t _Ip, class... _Types> 280 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { 281 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 282 using type = __type_pack_element<_Ip, _Types...>; 283 }; 284 285 constexpr size_t variant_npos = static_cast<size_t>(-1); 286 constexpr unsigned int __variant_npos = static_cast<unsigned int>(-1); 287 288 namespace __find_detail { 289 290 template <class _Tp, class... _Types> 291 inline _LIBCPP_INLINE_VISIBILITY 292 constexpr size_t __find_index() { 293 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 294 size_t __result = __not_found; 295 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 296 if (__matches[__i]) { 297 if (__result != __not_found) { 298 return __ambiguous; 299 } 300 __result = __i; 301 } 302 } 303 return __result; 304 } 305 306 template <size_t _Index> 307 struct __find_unambiguous_index_sfinae_impl 308 : integral_constant<size_t, _Index> {}; 309 310 template <> 311 struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 312 313 template <> 314 struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 315 316 template <class _Tp, class... _Types> 317 struct __find_unambiguous_index_sfinae 318 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {}; 319 320 } // namespace __find_detail 321 322 namespace __variant_detail { 323 324 struct __valueless_t {}; 325 326 enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 327 328 template <typename _Tp, 329 template <typename> class _IsTriviallyAvailable, 330 template <typename> class _IsAvailable> 331 constexpr _Trait __trait = 332 _IsTriviallyAvailable<_Tp>::value 333 ? _Trait::_TriviallyAvailable 334 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable; 335 336 inline _LIBCPP_INLINE_VISIBILITY 337 constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 338 _Trait __result = _Trait::_TriviallyAvailable; 339 for (_Trait __t : __traits) { 340 if (static_cast<int>(__t) > static_cast<int>(__result)) { 341 __result = __t; 342 } 343 } 344 return __result; 345 } 346 347 template <typename... _Types> 348 struct __traits { 349 static constexpr _Trait __copy_constructible_trait = 350 __common_trait({__trait<_Types, 351 is_trivially_copy_constructible, 352 is_copy_constructible>...}); 353 354 static constexpr _Trait __move_constructible_trait = 355 __common_trait({__trait<_Types, 356 is_trivially_move_constructible, 357 is_move_constructible>...}); 358 359 static constexpr _Trait __copy_assignable_trait = __common_trait( 360 {__copy_constructible_trait, 361 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 362 363 static constexpr _Trait __move_assignable_trait = __common_trait( 364 {__move_constructible_trait, 365 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 366 367 static constexpr _Trait __destructible_trait = __common_trait( 368 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 369 }; 370 371 namespace __access { 372 373 struct __union { 374 template <class _Vp> 375 inline _LIBCPP_INLINE_VISIBILITY 376 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 377 return _VSTD::forward<_Vp>(__v).__head; 378 } 379 380 template <class _Vp, size_t _Ip> 381 inline _LIBCPP_INLINE_VISIBILITY 382 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 383 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 384 } 385 }; 386 387 struct __base { 388 template <size_t _Ip, class _Vp> 389 inline _LIBCPP_INLINE_VISIBILITY 390 static constexpr auto&& __get_alt(_Vp&& __v) { 391 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data, 392 in_place_index<_Ip>); 393 } 394 }; 395 396 struct __variant { 397 template <size_t _Ip, class _Vp> 398 inline _LIBCPP_INLINE_VISIBILITY 399 static constexpr auto&& __get_alt(_Vp&& __v) { 400 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl); 401 } 402 }; 403 404 } // namespace __access 405 406 namespace __visitation { 407 408 struct __base { 409 template <class _Visitor, class... _Vs> 410 inline _LIBCPP_INLINE_VISIBILITY 411 static constexpr decltype(auto) 412 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 413 constexpr auto __fdiagonal = 414 __make_fdiagonal<_Visitor&&, 415 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 416 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor), 417 _VSTD::forward<_Vs>(__vs).__as_base()...); 418 } 419 420 template <class _Visitor, class... _Vs> 421 inline _LIBCPP_INLINE_VISIBILITY 422 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 423 _Vs&&... __vs) { 424 constexpr auto __fmatrix = 425 __make_fmatrix<_Visitor&&, 426 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 427 return __at(__fmatrix, __vs.index()...)( 428 _VSTD::forward<_Visitor>(__visitor), 429 _VSTD::forward<_Vs>(__vs).__as_base()...); 430 } 431 432 private: 433 template <class _Tp> 434 inline _LIBCPP_INLINE_VISIBILITY 435 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; } 436 437 template <class _Tp, size_t _Np, typename... _Indices> 438 inline _LIBCPP_INLINE_VISIBILITY 439 static constexpr auto&& __at(const array<_Tp, _Np>& __elems, 440 size_t __index, _Indices... __indices) { 441 return __at(__elems[__index], __indices...); 442 } 443 444 template <class _Fp, class... _Fs> 445 static constexpr void __std_visit_visitor_return_type_check() { 446 static_assert( 447 __all<is_same_v<_Fp, _Fs>...>::value, 448 "`std::visit` requires the visitor to have a single return type."); 449 } 450 451 template <class... _Fs> 452 inline _LIBCPP_INLINE_VISIBILITY 453 static constexpr auto __make_farray(_Fs&&... __fs) { 454 __std_visit_visitor_return_type_check<decay_t<_Fs>...>(); 455 using __result = array<common_type_t<decay_t<_Fs>...>, sizeof...(_Fs)>; 456 return __result{{_VSTD::forward<_Fs>(__fs)...}}; 457 } 458 459 template <std::size_t... _Is> 460 struct __dispatcher { 461 template <class _Fp, class... _Vs> 462 inline _LIBCPP_INLINE_VISIBILITY 463 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 464 return __invoke_constexpr( 465 static_cast<_Fp>(__f), 466 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 467 } 468 }; 469 470 template <class _Fp, class... _Vs, size_t... _Is> 471 inline _LIBCPP_INLINE_VISIBILITY 472 static constexpr auto __make_dispatch(index_sequence<_Is...>) { 473 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 474 } 475 476 template <size_t _Ip, class _Fp, class... _Vs> 477 inline _LIBCPP_INLINE_VISIBILITY 478 static constexpr auto __make_fdiagonal_impl() { 479 return __make_dispatch<_Fp, _Vs...>( 480 index_sequence<(__identity<_Vs>{}, _Ip)...>{}); 481 } 482 483 template <class _Fp, class... _Vs, size_t... _Is> 484 inline _LIBCPP_INLINE_VISIBILITY 485 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 486 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 487 } 488 489 template <class _Fp, class _Vp, class... _Vs> 490 inline _LIBCPP_INLINE_VISIBILITY 491 static constexpr auto __make_fdiagonal() { 492 constexpr size_t _Np = decay_t<_Vp>::__size(); 493 static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value); 494 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{}); 495 } 496 497 template <class _Fp, class... _Vs, size_t... _Is> 498 inline _LIBCPP_INLINE_VISIBILITY 499 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 500 return __make_dispatch<_Fp, _Vs...>(__is); 501 } 502 503 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 504 inline _LIBCPP_INLINE_VISIBILITY 505 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>, 506 index_sequence<_Js...>, 507 _Ls... __ls) { 508 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>( 509 index_sequence<_Is..., _Js>{}, __ls...)...); 510 } 511 512 template <class _Fp, class... _Vs> 513 inline _LIBCPP_INLINE_VISIBILITY 514 static constexpr auto __make_fmatrix() { 515 return __make_fmatrix_impl<_Fp, _Vs...>( 516 index_sequence<>{}, make_index_sequence<decay_t<_Vs>::__size()>{}...); 517 } 518 }; 519 520 struct __variant { 521 template <class _Visitor, class... _Vs> 522 inline _LIBCPP_INLINE_VISIBILITY 523 static constexpr decltype(auto) 524 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 525 return __base::__visit_alt_at(__index, 526 _VSTD::forward<_Visitor>(__visitor), 527 _VSTD::forward<_Vs>(__vs).__impl...); 528 } 529 530 template <class _Visitor, class... _Vs> 531 inline _LIBCPP_INLINE_VISIBILITY 532 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 533 _Vs&&... __vs) { 534 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor), 535 _VSTD::forward<_Vs>(__vs).__impl...); 536 } 537 538 template <class _Visitor, class... _Vs> 539 inline _LIBCPP_INLINE_VISIBILITY 540 static constexpr decltype(auto) 541 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 542 return __visit_alt_at( 543 __index, 544 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 545 _VSTD::forward<_Vs>(__vs)...); 546 } 547 548 template <class _Visitor, class... _Vs> 549 inline _LIBCPP_INLINE_VISIBILITY 550 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, 551 _Vs&&... __vs) { 552 return __visit_alt( 553 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 554 _VSTD::forward<_Vs>(__vs)...); 555 } 556 557 private: 558 template <class _Visitor, class... _Values> 559 static constexpr void __std_visit_exhaustive_visitor_check() { 560 static_assert(is_callable_v<_Visitor(_Values...)>, 561 "`std::visit` requires the visitor to be exhaustive."); 562 } 563 564 template <class _Visitor> 565 struct __value_visitor { 566 template <class... _Alts> 567 inline _LIBCPP_INLINE_VISIBILITY 568 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 569 __std_visit_exhaustive_visitor_check< 570 _Visitor, 571 decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 572 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 573 _VSTD::forward<_Alts>(__alts).__value...); 574 } 575 _Visitor&& __visitor; 576 }; 577 578 template <class _Visitor> 579 inline _LIBCPP_INLINE_VISIBILITY 580 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 581 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)}; 582 } 583 }; 584 585 } // namespace __visitation 586 587 template <size_t _Index, class _Tp> 588 struct _LIBCPP_TEMPLATE_VIS __alt { 589 using __value_type = _Tp; 590 591 template <class... _Args> 592 inline _LIBCPP_INLINE_VISIBILITY 593 explicit constexpr __alt(in_place_t, _Args&&... __args) 594 : __value(_VSTD::forward<_Args>(__args)...) {} 595 596 __value_type __value; 597 }; 598 599 template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 600 union _LIBCPP_TEMPLATE_VIS __union; 601 602 template <_Trait _DestructibleTrait, size_t _Index> 603 union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 604 605 #define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 606 template <size_t _Index, class _Tp, class... _Types> \ 607 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 608 _Index, \ 609 _Tp, \ 610 _Types...> { \ 611 public: \ 612 inline _LIBCPP_INLINE_VISIBILITY \ 613 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 614 \ 615 template <class... _Args> \ 616 inline _LIBCPP_INLINE_VISIBILITY \ 617 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 618 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \ 619 \ 620 template <size_t _Ip, class... _Args> \ 621 inline _LIBCPP_INLINE_VISIBILITY \ 622 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 623 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \ 624 \ 625 __union(const __union&) = default; \ 626 __union(__union&&) = default; \ 627 \ 628 destructor \ 629 \ 630 __union& operator=(const __union&) = default; \ 631 __union& operator=(__union&&) = default; \ 632 \ 633 private: \ 634 char __dummy; \ 635 __alt<_Index, _Tp> __head; \ 636 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 637 \ 638 friend struct __access::__union; \ 639 } 640 641 _LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 642 _LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 643 _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 644 645 #undef _LIBCPP_VARIANT_UNION 646 647 template <_Trait _DestructibleTrait, class... _Types> 648 class _LIBCPP_TEMPLATE_VIS __base { 649 public: 650 inline _LIBCPP_INLINE_VISIBILITY 651 explicit constexpr __base(__valueless_t tag) noexcept 652 : __data(tag), __index(__variant_npos) {} 653 654 template <size_t _Ip, class... _Args> 655 inline _LIBCPP_INLINE_VISIBILITY 656 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 657 : 658 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...), 659 __index(_Ip) {} 660 661 inline _LIBCPP_INLINE_VISIBILITY 662 constexpr bool valueless_by_exception() const noexcept { 663 return index() == variant_npos; 664 } 665 666 inline _LIBCPP_INLINE_VISIBILITY 667 constexpr size_t index() const noexcept { 668 return __index == __variant_npos ? variant_npos : __index; 669 } 670 671 protected: 672 inline _LIBCPP_INLINE_VISIBILITY 673 constexpr auto&& __as_base() & { return *this; } 674 675 inline _LIBCPP_INLINE_VISIBILITY 676 constexpr auto&& __as_base() && { return _VSTD::move(*this); } 677 678 inline _LIBCPP_INLINE_VISIBILITY 679 constexpr auto&& __as_base() const & { return *this; } 680 681 inline _LIBCPP_INLINE_VISIBILITY 682 constexpr auto&& __as_base() const && { return _VSTD::move(*this); } 683 684 inline _LIBCPP_INLINE_VISIBILITY 685 static constexpr size_t __size() { return sizeof...(_Types); } 686 687 __union<_DestructibleTrait, 0, _Types...> __data; 688 unsigned int __index; 689 690 friend struct __access::__base; 691 friend struct __visitation::__base; 692 }; 693 694 template <class _Traits, _Trait = _Traits::__destructible_trait> 695 class _LIBCPP_TEMPLATE_VIS __destructor; 696 697 #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 698 template <class... _Types> \ 699 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \ 700 destructible_trait> \ 701 : public __base<destructible_trait, _Types...> { \ 702 using __base_type = __base<destructible_trait, _Types...>; \ 703 \ 704 public: \ 705 using __base_type::__base_type; \ 706 using __base_type::operator=; \ 707 \ 708 __destructor(const __destructor&) = default; \ 709 __destructor(__destructor&&) = default; \ 710 destructor \ 711 __destructor& operator=(const __destructor&) = default; \ 712 __destructor& operator=(__destructor&&) = default; \ 713 \ 714 protected: \ 715 inline _LIBCPP_INLINE_VISIBILITY \ 716 destroy \ 717 } 718 719 _LIBCPP_VARIANT_DESTRUCTOR( 720 _Trait::_TriviallyAvailable, 721 ~__destructor() = default;, 722 void __destroy() noexcept { this->__index = __variant_npos; }); 723 724 _LIBCPP_VARIANT_DESTRUCTOR( 725 _Trait::_Available, 726 ~__destructor() { __destroy(); }, 727 void __destroy() noexcept { 728 if (!this->valueless_by_exception()) { 729 __visitation::__base::__visit_alt( 730 [](auto& __alt) noexcept { 731 using __alt_type = decay_t<decltype(__alt)>; 732 __alt.~__alt_type(); 733 }, 734 *this); 735 } 736 this->__index = __variant_npos; 737 }); 738 739 _LIBCPP_VARIANT_DESTRUCTOR( 740 _Trait::_Unavailable, 741 ~__destructor() = delete;, 742 void __destroy() noexcept = delete;); 743 744 #undef _LIBCPP_VARIANT_DESTRUCTOR 745 746 template <class _Traits> 747 class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> { 748 using __base_type = __destructor<_Traits>; 749 750 public: 751 using __base_type::__base_type; 752 using __base_type::operator=; 753 754 protected: 755 template <size_t _Ip, class _Tp, class... _Args> 756 inline _LIBCPP_INLINE_VISIBILITY 757 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 758 ::new ((void*)_VSTD::addressof(__a)) 759 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); 760 return __a.__value; 761 } 762 763 template <class _Rhs> 764 inline _LIBCPP_INLINE_VISIBILITY 765 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) { 766 __lhs.__destroy(); 767 if (!__rhs.valueless_by_exception()) { 768 __visitation::__base::__visit_alt_at( 769 __rhs.index(), 770 [](auto& __lhs_alt, auto&& __rhs_alt) { 771 __construct_alt( 772 __lhs_alt, 773 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 774 }, 775 __lhs, _VSTD::forward<_Rhs>(__rhs)); 776 __lhs.__index = __rhs.index(); 777 } 778 } 779 }; 780 781 template <class _Traits, _Trait = _Traits::__move_constructible_trait> 782 class _LIBCPP_TEMPLATE_VIS __move_constructor; 783 784 #define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 785 move_constructor) \ 786 template <class... _Types> \ 787 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 788 move_constructible_trait> \ 789 : public __constructor<__traits<_Types...>> { \ 790 using __base_type = __constructor<__traits<_Types...>>; \ 791 \ 792 public: \ 793 using __base_type::__base_type; \ 794 using __base_type::operator=; \ 795 \ 796 __move_constructor(const __move_constructor&) = default; \ 797 move_constructor \ 798 ~__move_constructor() = default; \ 799 __move_constructor& operator=(const __move_constructor&) = default; \ 800 __move_constructor& operator=(__move_constructor&&) = default; \ 801 } 802 803 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 804 _Trait::_TriviallyAvailable, 805 __move_constructor(__move_constructor&& __that) = default;); 806 807 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 808 _Trait::_Available, 809 __move_constructor(__move_constructor&& __that) noexcept( 810 __all<is_nothrow_move_constructible_v<_Types>...>::value) 811 : __move_constructor(__valueless_t{}) { 812 this->__generic_construct(*this, _VSTD::move(__that)); 813 }); 814 815 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 816 _Trait::_Unavailable, 817 __move_constructor(__move_constructor&&) = delete;); 818 819 #undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 820 821 template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 822 class _LIBCPP_TEMPLATE_VIS __copy_constructor; 823 824 #define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 825 copy_constructor) \ 826 template <class... _Types> \ 827 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 828 copy_constructible_trait> \ 829 : public __move_constructor<__traits<_Types...>> { \ 830 using __base_type = __move_constructor<__traits<_Types...>>; \ 831 \ 832 public: \ 833 using __base_type::__base_type; \ 834 using __base_type::operator=; \ 835 \ 836 copy_constructor \ 837 __copy_constructor(__copy_constructor&&) = default; \ 838 ~__copy_constructor() = default; \ 839 __copy_constructor& operator=(const __copy_constructor&) = default; \ 840 __copy_constructor& operator=(__copy_constructor&&) = default; \ 841 } 842 843 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 844 _Trait::_TriviallyAvailable, 845 __copy_constructor(const __copy_constructor& __that) = default;); 846 847 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 848 _Trait::_Available, 849 __copy_constructor(const __copy_constructor& __that) 850 : __copy_constructor(__valueless_t{}) { 851 this->__generic_construct(*this, __that); 852 }); 853 854 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 855 _Trait::_Unavailable, 856 __copy_constructor(const __copy_constructor&) = delete;); 857 858 #undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 859 860 template <class _Traits> 861 class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 862 using __base_type = __copy_constructor<_Traits>; 863 864 public: 865 using __base_type::__base_type; 866 using __base_type::operator=; 867 868 template <size_t _Ip, class... _Args> 869 inline _LIBCPP_INLINE_VISIBILITY 870 auto& __emplace(_Args&&... __args) { 871 this->__destroy(); 872 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 873 _VSTD::forward<_Args>(__args)...); 874 this->__index = _Ip; 875 return __res; 876 } 877 878 protected: 879 template <size_t _Ip, class _Tp, class _Arg> 880 inline _LIBCPP_INLINE_VISIBILITY 881 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 882 if (this->index() == _Ip) { 883 __a.__value = _VSTD::forward<_Arg>(__arg); 884 } else { 885 struct { 886 void operator()(true_type) const { 887 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg)); 888 } 889 void operator()(false_type) const { 890 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg))); 891 } 892 __assignment* __this; 893 _Arg&& __arg; 894 } __impl{this, _VSTD::forward<_Arg>(__arg)}; 895 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> || 896 !is_nothrow_move_constructible_v<_Tp>>{}); 897 } 898 } 899 900 template <class _That> 901 inline _LIBCPP_INLINE_VISIBILITY 902 void __generic_assign(_That&& __that) { 903 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 904 // do nothing. 905 } else if (__that.valueless_by_exception()) { 906 this->__destroy(); 907 } else { 908 __visitation::__base::__visit_alt_at( 909 __that.index(), 910 [this](auto& __this_alt, auto&& __that_alt) { 911 this->__assign_alt( 912 __this_alt, 913 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value); 914 }, 915 *this, _VSTD::forward<_That>(__that)); 916 } 917 } 918 }; 919 920 template <class _Traits, _Trait = _Traits::__move_assignable_trait> 921 class _LIBCPP_TEMPLATE_VIS __move_assignment; 922 923 #define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 924 move_assignment) \ 925 template <class... _Types> \ 926 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 927 move_assignable_trait> \ 928 : public __assignment<__traits<_Types...>> { \ 929 using __base_type = __assignment<__traits<_Types...>>; \ 930 \ 931 public: \ 932 using __base_type::__base_type; \ 933 using __base_type::operator=; \ 934 \ 935 __move_assignment(const __move_assignment&) = default; \ 936 __move_assignment(__move_assignment&&) = default; \ 937 ~__move_assignment() = default; \ 938 __move_assignment& operator=(const __move_assignment&) = default; \ 939 move_assignment \ 940 } 941 942 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 943 _Trait::_TriviallyAvailable, 944 __move_assignment& operator=(__move_assignment&& __that) = default;); 945 946 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 947 _Trait::_Available, 948 __move_assignment& operator=(__move_assignment&& __that) noexcept( 949 __all<(is_nothrow_move_constructible_v<_Types> && 950 is_nothrow_move_assignable_v<_Types>)...>::value) { 951 this->__generic_assign(_VSTD::move(__that)); 952 return *this; 953 }); 954 955 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 956 _Trait::_Unavailable, 957 __move_assignment& operator=(__move_assignment&&) = delete;); 958 959 #undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 960 961 template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 962 class _LIBCPP_TEMPLATE_VIS __copy_assignment; 963 964 #define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 965 copy_assignment) \ 966 template <class... _Types> \ 967 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 968 copy_assignable_trait> \ 969 : public __move_assignment<__traits<_Types...>> { \ 970 using __base_type = __move_assignment<__traits<_Types...>>; \ 971 \ 972 public: \ 973 using __base_type::__base_type; \ 974 using __base_type::operator=; \ 975 \ 976 __copy_assignment(const __copy_assignment&) = default; \ 977 __copy_assignment(__copy_assignment&&) = default; \ 978 ~__copy_assignment() = default; \ 979 copy_assignment \ 980 __copy_assignment& operator=(__copy_assignment&&) = default; \ 981 } 982 983 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 984 _Trait::_TriviallyAvailable, 985 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 986 987 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 988 _Trait::_Available, 989 __copy_assignment& operator=(const __copy_assignment& __that) { 990 this->__generic_assign(__that); 991 return *this; 992 }); 993 994 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 995 _Trait::_Unavailable, 996 __copy_assignment& operator=(const __copy_assignment&) = delete;); 997 998 #undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 999 1000 template <class... _Types> 1001 class _LIBCPP_TEMPLATE_VIS __impl 1002 : public __copy_assignment<__traits<_Types...>> { 1003 using __base_type = __copy_assignment<__traits<_Types...>>; 1004 1005 public: 1006 using __base_type::__base_type; 1007 using __base_type::operator=; 1008 1009 template <size_t _Ip, class _Arg> 1010 inline _LIBCPP_INLINE_VISIBILITY 1011 void __assign(_Arg&& __arg) { 1012 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1013 _VSTD::forward<_Arg>(__arg)); 1014 } 1015 1016 inline _LIBCPP_INLINE_VISIBILITY 1017 void __swap(__impl& __that) { 1018 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1019 // do nothing. 1020 } else if (this->index() == __that.index()) { 1021 __visitation::__base::__visit_alt_at( 1022 this->index(), 1023 [](auto& __this_alt, auto& __that_alt) { 1024 using _VSTD::swap; 1025 swap(__this_alt.__value, __that_alt.__value); 1026 }, 1027 *this, 1028 __that); 1029 } else { 1030 __impl* __lhs = this; 1031 __impl* __rhs = _VSTD::addressof(__that); 1032 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1033 _VSTD::swap(__lhs, __rhs); 1034 } 1035 __impl __tmp(_VSTD::move(*__rhs)); 1036 #ifndef _LIBCPP_NO_EXCEPTIONS 1037 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1038 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1039 // into `__rhs` and provide the strong exception safety guarentee. 1040 try { 1041 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1042 } catch (...) { 1043 if (__tmp.__move_nothrow()) { 1044 this->__generic_construct(*__rhs, _VSTD::move(__tmp)); 1045 } 1046 throw; 1047 } 1048 #else 1049 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1050 #endif 1051 this->__generic_construct(*__lhs, _VSTD::move(__tmp)); 1052 } 1053 } 1054 1055 private: 1056 inline _LIBCPP_INLINE_VISIBILITY 1057 bool __move_nothrow() const { 1058 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1059 return this->valueless_by_exception() || __results[this->index()]; 1060 } 1061 }; 1062 1063 template <class... _Types> 1064 struct __overload; 1065 1066 template <> 1067 struct __overload<> { void operator()() const; }; 1068 1069 template <class _Tp, class... _Types> 1070 struct __overload<_Tp, _Types...> : __overload<_Types...> { 1071 using __overload<_Types...>::operator(); 1072 __identity<_Tp> operator()(_Tp) const; 1073 }; 1074 1075 template <class _Tp, class... _Types> 1076 using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type; 1077 1078 } // __variant_detail 1079 1080 template <class... _Types> 1081 class _LIBCPP_TEMPLATE_VIS variant 1082 : private __sfinae_ctor_base< 1083 __all<is_copy_constructible_v<_Types>...>::value, 1084 __all<is_move_constructible_v<_Types>...>::value>, 1085 private __sfinae_assign_base< 1086 __all<(is_copy_constructible_v<_Types> && 1087 is_copy_assignable_v<_Types>)...>::value, 1088 __all<(is_move_constructible_v<_Types> && 1089 is_move_assignable_v<_Types>)...>::value> { 1090 static_assert(0 < sizeof...(_Types), 1091 "variant must consist of at least one alternative."); 1092 1093 static_assert(__all<!is_array_v<_Types>...>::value, 1094 "variant can not have an array type as an alternative."); 1095 1096 static_assert(__all<!is_reference_v<_Types>...>::value, 1097 "variant can not have a reference type as an alternative."); 1098 1099 static_assert(__all<!is_void_v<_Types>...>::value, 1100 "variant can not have a void type as an alternative."); 1101 1102 using __first_type = variant_alternative_t<0, variant>; 1103 1104 public: 1105 template <bool _Dummy = true, 1106 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1107 _Dummy>::value, 1108 int> = 0> 1109 inline _LIBCPP_INLINE_VISIBILITY 1110 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1111 : __impl(in_place_index<0>) {} 1112 1113 variant(const variant&) = default; 1114 variant(variant&&) = default; 1115 1116 template < 1117 class _Arg, 1118 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0, 1119 enable_if_t<!__is_inplace_type<decay_t<_Arg>>::value, int> = 0, 1120 enable_if_t<!__is_inplace_index<decay_t<_Arg>>::value, int> = 0, 1121 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1122 size_t _Ip = 1123 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1124 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1125 inline _LIBCPP_INLINE_VISIBILITY 1126 constexpr variant(_Arg&& __arg) noexcept( 1127 is_nothrow_constructible_v<_Tp, _Arg>) 1128 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {} 1129 1130 template <size_t _Ip, class... _Args, 1131 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1132 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1133 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1134 inline _LIBCPP_INLINE_VISIBILITY 1135 explicit constexpr variant( 1136 in_place_index_t<_Ip>, 1137 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1138 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1139 1140 template < 1141 size_t _Ip, 1142 class _Up, 1143 class... _Args, 1144 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1145 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1146 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1147 int> = 0> 1148 inline _LIBCPP_INLINE_VISIBILITY 1149 explicit constexpr variant( 1150 in_place_index_t<_Ip>, 1151 initializer_list<_Up> __il, 1152 _Args&&... __args) noexcept( 1153 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1154 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1155 1156 template < 1157 class _Tp, 1158 class... _Args, 1159 size_t _Ip = 1160 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1161 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1162 inline _LIBCPP_INLINE_VISIBILITY 1163 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1164 is_nothrow_constructible_v<_Tp, _Args...>) 1165 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1166 1167 template < 1168 class _Tp, 1169 class _Up, 1170 class... _Args, 1171 size_t _Ip = 1172 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1173 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1174 int> = 0> 1175 inline _LIBCPP_INLINE_VISIBILITY 1176 explicit constexpr variant( 1177 in_place_type_t<_Tp>, 1178 initializer_list<_Up> __il, 1179 _Args&&... __args) noexcept( 1180 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1181 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1182 1183 ~variant() = default; 1184 1185 variant& operator=(const variant&) = default; 1186 variant& operator=(variant&&) = default; 1187 1188 template < 1189 class _Arg, 1190 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0, 1191 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1192 size_t _Ip = 1193 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1194 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1195 int> = 0> 1196 inline _LIBCPP_INLINE_VISIBILITY 1197 variant& operator=(_Arg&& __arg) noexcept( 1198 is_nothrow_assignable_v<_Tp&, _Arg> && 1199 is_nothrow_constructible_v<_Tp, _Arg>) { 1200 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg)); 1201 return *this; 1202 } 1203 1204 template < 1205 size_t _Ip, 1206 class... _Args, 1207 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1208 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1209 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1210 inline _LIBCPP_INLINE_VISIBILITY 1211 _Tp& emplace(_Args&&... __args) { 1212 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1213 } 1214 1215 template < 1216 size_t _Ip, 1217 class _Up, 1218 class... _Args, 1219 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1220 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1221 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1222 int> = 0> 1223 inline _LIBCPP_INLINE_VISIBILITY 1224 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1225 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1226 } 1227 1228 template < 1229 class _Tp, 1230 class... _Args, 1231 size_t _Ip = 1232 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1233 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1234 inline _LIBCPP_INLINE_VISIBILITY 1235 _Tp& emplace(_Args&&... __args) { 1236 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1237 } 1238 1239 template < 1240 class _Tp, 1241 class _Up, 1242 class... _Args, 1243 size_t _Ip = 1244 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1245 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1246 int> = 0> 1247 inline _LIBCPP_INLINE_VISIBILITY 1248 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1249 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1250 } 1251 1252 inline _LIBCPP_INLINE_VISIBILITY 1253 constexpr bool valueless_by_exception() const noexcept { 1254 return __impl.valueless_by_exception(); 1255 } 1256 1257 inline _LIBCPP_INLINE_VISIBILITY 1258 constexpr size_t index() const noexcept { return __impl.index(); } 1259 1260 template < 1261 bool _Dummy = true, 1262 enable_if_t< 1263 __all<( 1264 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1265 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1266 int> = 0> 1267 inline _LIBCPP_INLINE_VISIBILITY 1268 void swap(variant& __that) noexcept( 1269 __all<(is_nothrow_move_constructible_v<_Types> && 1270 is_nothrow_swappable_v<_Types>)...>::value) { 1271 __impl.__swap(__that.__impl); 1272 } 1273 1274 private: 1275 __variant_detail::__impl<_Types...> __impl; 1276 1277 friend struct __variant_detail::__access::__variant; 1278 friend struct __variant_detail::__visitation::__variant; 1279 }; 1280 1281 template <size_t _Ip, class... _Types> 1282 inline _LIBCPP_INLINE_VISIBILITY 1283 constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1284 return __v.index() == _Ip; 1285 } 1286 1287 template <class _Tp, class... _Types> 1288 inline _LIBCPP_INLINE_VISIBILITY 1289 constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1290 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1291 } 1292 1293 template <size_t _Ip, class _Vp> 1294 inline _LIBCPP_INLINE_VISIBILITY 1295 static constexpr auto&& __generic_get(_Vp&& __v) { 1296 using __variant_detail::__access::__variant; 1297 if (!__holds_alternative<_Ip>(__v)) { 1298 __throw_bad_variant_access(); 1299 } 1300 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1301 } 1302 1303 template <size_t _Ip, class... _Types> 1304 inline _LIBCPP_INLINE_VISIBILITY 1305 constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1306 variant<_Types...>& __v) { 1307 static_assert(_Ip < sizeof...(_Types)); 1308 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1309 return __generic_get<_Ip>(__v); 1310 } 1311 1312 template <size_t _Ip, class... _Types> 1313 inline _LIBCPP_INLINE_VISIBILITY 1314 constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1315 variant<_Types...>&& __v) { 1316 static_assert(_Ip < sizeof...(_Types)); 1317 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1318 return __generic_get<_Ip>(_VSTD::move(__v)); 1319 } 1320 1321 template <size_t _Ip, class... _Types> 1322 inline _LIBCPP_INLINE_VISIBILITY 1323 constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1324 const variant<_Types...>& __v) { 1325 static_assert(_Ip < sizeof...(_Types)); 1326 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1327 return __generic_get<_Ip>(__v); 1328 } 1329 1330 template <size_t _Ip, class... _Types> 1331 inline _LIBCPP_INLINE_VISIBILITY 1332 constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1333 const variant<_Types...>&& __v) { 1334 static_assert(_Ip < sizeof...(_Types)); 1335 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1336 return __generic_get<_Ip>(_VSTD::move(__v)); 1337 } 1338 1339 template <class _Tp, class... _Types> 1340 inline _LIBCPP_INLINE_VISIBILITY 1341 constexpr _Tp& get(variant<_Types...>& __v) { 1342 static_assert(!is_void_v<_Tp>); 1343 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1344 } 1345 1346 template <class _Tp, class... _Types> 1347 inline _LIBCPP_INLINE_VISIBILITY 1348 constexpr _Tp&& get(variant<_Types...>&& __v) { 1349 static_assert(!is_void_v<_Tp>); 1350 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1351 _VSTD::move(__v)); 1352 } 1353 1354 template <class _Tp, class... _Types> 1355 inline _LIBCPP_INLINE_VISIBILITY 1356 constexpr const _Tp& get(const variant<_Types...>& __v) { 1357 static_assert(!is_void_v<_Tp>); 1358 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1359 } 1360 1361 template <class _Tp, class... _Types> 1362 inline _LIBCPP_INLINE_VISIBILITY 1363 constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1364 static_assert(!is_void_v<_Tp>); 1365 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1366 _VSTD::move(__v)); 1367 } 1368 1369 template <size_t _Ip, class _Vp> 1370 inline _LIBCPP_INLINE_VISIBILITY 1371 constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1372 using __variant_detail::__access::__variant; 1373 return __v && __holds_alternative<_Ip>(*__v) 1374 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1375 : nullptr; 1376 } 1377 1378 template <size_t _Ip, class... _Types> 1379 inline _LIBCPP_INLINE_VISIBILITY 1380 constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1381 get_if(variant<_Types...>* __v) noexcept { 1382 static_assert(_Ip < sizeof...(_Types)); 1383 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1384 return __generic_get_if<_Ip>(__v); 1385 } 1386 1387 template <size_t _Ip, class... _Types> 1388 inline _LIBCPP_INLINE_VISIBILITY 1389 constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1390 get_if(const variant<_Types...>* __v) noexcept { 1391 static_assert(_Ip < sizeof...(_Types)); 1392 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1393 return __generic_get_if<_Ip>(__v); 1394 } 1395 1396 template <class _Tp, class... _Types> 1397 inline _LIBCPP_INLINE_VISIBILITY 1398 constexpr add_pointer_t<_Tp> 1399 get_if(variant<_Types...>* __v) noexcept { 1400 static_assert(!is_void_v<_Tp>); 1401 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1402 } 1403 1404 template <class _Tp, class... _Types> 1405 inline _LIBCPP_INLINE_VISIBILITY 1406 constexpr add_pointer_t<const _Tp> 1407 get_if(const variant<_Types...>* __v) noexcept { 1408 static_assert(!is_void_v<_Tp>); 1409 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1410 } 1411 1412 template <class... _Types> 1413 inline _LIBCPP_INLINE_VISIBILITY 1414 constexpr bool operator==(const variant<_Types...>& __lhs, 1415 const variant<_Types...>& __rhs) { 1416 using __variant_detail::__visitation::__variant; 1417 if (__lhs.index() != __rhs.index()) return false; 1418 if (__lhs.valueless_by_exception()) return true; 1419 return __variant::__visit_value_at(__lhs.index(), equal_to<>{}, __lhs, __rhs); 1420 } 1421 1422 template <class... _Types> 1423 inline _LIBCPP_INLINE_VISIBILITY 1424 constexpr bool operator!=(const variant<_Types...>& __lhs, 1425 const variant<_Types...>& __rhs) { 1426 using __variant_detail::__visitation::__variant; 1427 if (__lhs.index() != __rhs.index()) return true; 1428 if (__lhs.valueless_by_exception()) return false; 1429 return __variant::__visit_value_at( 1430 __lhs.index(), not_equal_to<>{}, __lhs, __rhs); 1431 } 1432 1433 template <class... _Types> 1434 inline _LIBCPP_INLINE_VISIBILITY 1435 constexpr bool operator<(const variant<_Types...>& __lhs, 1436 const variant<_Types...>& __rhs) { 1437 using __variant_detail::__visitation::__variant; 1438 if (__rhs.valueless_by_exception()) return false; 1439 if (__lhs.valueless_by_exception()) return true; 1440 if (__lhs.index() < __rhs.index()) return true; 1441 if (__lhs.index() > __rhs.index()) return false; 1442 return __variant::__visit_value_at(__lhs.index(), less<>{}, __lhs, __rhs); 1443 } 1444 1445 template <class... _Types> 1446 inline _LIBCPP_INLINE_VISIBILITY 1447 constexpr bool operator>(const variant<_Types...>& __lhs, 1448 const variant<_Types...>& __rhs) { 1449 using __variant_detail::__visitation::__variant; 1450 if (__lhs.valueless_by_exception()) return false; 1451 if (__rhs.valueless_by_exception()) return true; 1452 if (__lhs.index() > __rhs.index()) return true; 1453 if (__lhs.index() < __rhs.index()) return false; 1454 return __variant::__visit_value_at(__lhs.index(), greater<>{}, __lhs, __rhs); 1455 } 1456 1457 template <class... _Types> 1458 inline _LIBCPP_INLINE_VISIBILITY 1459 constexpr bool operator<=(const variant<_Types...>& __lhs, 1460 const variant<_Types...>& __rhs) { 1461 using __variant_detail::__visitation::__variant; 1462 if (__lhs.valueless_by_exception()) return true; 1463 if (__rhs.valueless_by_exception()) return false; 1464 if (__lhs.index() < __rhs.index()) return true; 1465 if (__lhs.index() > __rhs.index()) return false; 1466 return __variant::__visit_value_at( 1467 __lhs.index(), less_equal<>{}, __lhs, __rhs); 1468 } 1469 1470 template <class... _Types> 1471 inline _LIBCPP_INLINE_VISIBILITY 1472 constexpr bool operator>=(const variant<_Types...>& __lhs, 1473 const variant<_Types...>& __rhs) { 1474 using __variant_detail::__visitation::__variant; 1475 if (__rhs.valueless_by_exception()) return true; 1476 if (__lhs.valueless_by_exception()) return false; 1477 if (__lhs.index() > __rhs.index()) return true; 1478 if (__lhs.index() < __rhs.index()) return false; 1479 return __variant::__visit_value_at( 1480 __lhs.index(), greater_equal<>{}, __lhs, __rhs); 1481 } 1482 1483 template <class _Visitor, class... _Vs> 1484 inline _LIBCPP_INLINE_VISIBILITY 1485 constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1486 using __variant_detail::__visitation::__variant; 1487 bool __results[] = {__vs.valueless_by_exception()...}; 1488 for (bool __result : __results) { 1489 if (__result) { 1490 __throw_bad_variant_access(); 1491 } 1492 } 1493 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor), 1494 _VSTD::forward<_Vs>(__vs)...); 1495 } 1496 1497 struct _LIBCPP_TEMPLATE_VIS monostate {}; 1498 1499 inline _LIBCPP_INLINE_VISIBILITY 1500 constexpr bool operator<(monostate, monostate) noexcept { return false; } 1501 1502 inline _LIBCPP_INLINE_VISIBILITY 1503 constexpr bool operator>(monostate, monostate) noexcept { return false; } 1504 1505 inline _LIBCPP_INLINE_VISIBILITY 1506 constexpr bool operator<=(monostate, monostate) noexcept { return true; } 1507 1508 inline _LIBCPP_INLINE_VISIBILITY 1509 constexpr bool operator>=(monostate, monostate) noexcept { return true; } 1510 1511 inline _LIBCPP_INLINE_VISIBILITY 1512 constexpr bool operator==(monostate, monostate) noexcept { return true; } 1513 1514 inline _LIBCPP_INLINE_VISIBILITY 1515 constexpr bool operator!=(monostate, monostate) noexcept { return false; } 1516 1517 template <class... _Types> 1518 inline _LIBCPP_INLINE_VISIBILITY 1519 auto swap(variant<_Types...>& __lhs, 1520 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1521 -> decltype(__lhs.swap(__rhs)) { 1522 __lhs.swap(__rhs); 1523 } 1524 1525 template <class... _Types> 1526 struct _LIBCPP_TEMPLATE_VIS hash< 1527 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1528 using argument_type = variant<_Types...>; 1529 using result_type = size_t; 1530 1531 inline _LIBCPP_INLINE_VISIBILITY 1532 result_type operator()(const argument_type& __v) const { 1533 using __variant_detail::__visitation::__variant; 1534 size_t __res = 1535 __v.valueless_by_exception() 1536 ? 299792458 // Random value chosen by the universe upon creation 1537 : __variant::__visit_alt( 1538 [](const auto& __alt) { 1539 using __alt_type = decay_t<decltype(__alt)>; 1540 using __value_type = remove_const_t< 1541 typename __alt_type::__value_type>; 1542 return hash<__value_type>{}(__alt.__value); 1543 }, 1544 __v); 1545 return __hash_combine(__res, hash<size_t>{}(__v.index())); 1546 } 1547 }; 1548 1549 template <> 1550 struct _LIBCPP_TEMPLATE_VIS hash<monostate> { 1551 using argument_type = monostate; 1552 using result_type = size_t; 1553 1554 inline _LIBCPP_INLINE_VISIBILITY 1555 result_type operator()(const argument_type&) const _NOEXCEPT { 1556 return 66740831; // return a fundamentally attractive random value. 1557 } 1558 }; 1559 1560 #endif // _LIBCPP_STD_VER > 14 1561 1562 _LIBCPP_END_NAMESPACE_STD 1563 1564 #endif // _LIBCPP_VARIANT 1565
