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 void emplace(Args&&...); 57 58 template <class T, class U, class... Args> 59 void emplace(initializer_list<U>, Args&&...); 60 61 template <size_t I, class... Args> 62 void emplace(Args&&...); 63 64 template <size_t I, class U, class... Args> 65 void 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)); 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 __move_constructible_trait, 362 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 363 364 static constexpr _Trait __move_assignable_trait = __common_trait( 365 {__move_constructible_trait, 366 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 367 368 static constexpr _Trait __destructible_trait = __common_trait( 369 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 370 }; 371 372 namespace __access { 373 374 struct __union { 375 template <class _Vp> 376 inline _LIBCPP_INLINE_VISIBILITY 377 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 378 return _VSTD::forward<_Vp>(__v).__head; 379 } 380 381 template <class _Vp, size_t _Ip> 382 inline _LIBCPP_INLINE_VISIBILITY 383 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 384 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 385 } 386 }; 387 388 struct __base { 389 template <size_t _Ip, class _Vp> 390 inline _LIBCPP_INLINE_VISIBILITY 391 static constexpr auto&& __get_alt(_Vp&& __v) { 392 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data, 393 in_place_index<_Ip>); 394 } 395 }; 396 397 struct __variant { 398 template <size_t _Ip, class _Vp> 399 inline _LIBCPP_INLINE_VISIBILITY 400 static constexpr auto&& __get_alt(_Vp&& __v) { 401 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl); 402 } 403 }; 404 405 } // namespace __access 406 407 namespace __visitation { 408 409 struct __base { 410 template <class _Visitor, class... _Vs> 411 inline _LIBCPP_INLINE_VISIBILITY 412 static constexpr decltype(auto) 413 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 414 constexpr auto __fdiagonal = 415 __make_fdiagonal<_Visitor&&, 416 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 417 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor), 418 _VSTD::forward<_Vs>(__vs).__as_base()...); 419 } 420 421 template <class _Visitor, class... _Vs> 422 inline _LIBCPP_INLINE_VISIBILITY 423 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 424 _Vs&&... __vs) { 425 constexpr auto __fmatrix = 426 __make_fmatrix<_Visitor&&, 427 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 428 const size_t __indices[] = {__vs.index()...}; 429 return __at(__fmatrix, __indices)(_VSTD::forward<_Visitor>(__visitor), 430 _VSTD::forward<_Vs>(__vs).__as_base()...); 431 } 432 433 private: 434 template <class _Tp> 435 inline _LIBCPP_INLINE_VISIBILITY 436 static constexpr const _Tp& __at_impl(const _Tp& __elem, const size_t*) { 437 return __elem; 438 } 439 440 template <class _Tp, size_t _Np> 441 inline _LIBCPP_INLINE_VISIBILITY 442 static constexpr auto&& __at_impl(const array<_Tp, _Np>& __elems, 443 const size_t* __index) { 444 return __at_impl(__elems[*__index], __index + 1); 445 } 446 447 template <class _Tp, size_t _Np, size_t _Ip> 448 inline _LIBCPP_INLINE_VISIBILITY 449 static constexpr auto&& __at(const array<_Tp, _Np>& __elems, 450 const size_t (&__indices)[_Ip]) { 451 return __at_impl(__elems, begin(__indices)); 452 } 453 454 template <class _Fp, class... _Fs> 455 static constexpr void __std_visit_visitor_return_type_check() { 456 static_assert( 457 __all<is_same_v<_Fp, _Fs>...>::value, 458 "`std::visit` requires the visitor to have a single return type."); 459 } 460 461 template <class... _Fs> 462 inline _LIBCPP_INLINE_VISIBILITY 463 static constexpr auto __make_farray(_Fs&&... __fs) { 464 __std_visit_visitor_return_type_check<decay_t<_Fs>...>(); 465 using __result = array<common_type_t<decay_t<_Fs>...>, sizeof...(_Fs)>; 466 return __result{{_VSTD::forward<_Fs>(__fs)...}}; 467 } 468 469 template <std::size_t... _Is> 470 struct __dispatcher { 471 template <class _Fp, class... _Vs> 472 inline _LIBCPP_INLINE_VISIBILITY 473 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 474 return __invoke_constexpr( 475 static_cast<_Fp>(__f), 476 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 477 } 478 }; 479 480 template <class _Fp, class... _Vs, size_t... _Is> 481 inline _LIBCPP_INLINE_VISIBILITY 482 static constexpr auto __make_dispatch(index_sequence<_Is...>) { 483 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 484 } 485 486 template <size_t _Ip, class _Fp, class... _Vs> 487 inline _LIBCPP_INLINE_VISIBILITY 488 static constexpr auto __make_fdiagonal_impl() { 489 return __make_dispatch<_Fp, _Vs...>( 490 index_sequence<(__identity<_Vs>{}, _Ip)...>{}); 491 } 492 493 template <class _Fp, class... _Vs, size_t... _Is> 494 inline _LIBCPP_INLINE_VISIBILITY 495 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 496 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 497 } 498 499 template <class _Fp, class _Vp, class... _Vs> 500 inline _LIBCPP_INLINE_VISIBILITY 501 static constexpr auto __make_fdiagonal() { 502 constexpr size_t _Np = decay_t<_Vp>::__size(); 503 static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value); 504 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{}); 505 } 506 507 template <class _Fp, class... _Vs, size_t... _Is> 508 inline _LIBCPP_INLINE_VISIBILITY 509 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 510 return __make_dispatch<_Fp, _Vs...>(__is); 511 } 512 513 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 514 inline _LIBCPP_INLINE_VISIBILITY 515 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>, 516 index_sequence<_Js...>, 517 _Ls... __ls) { 518 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>( 519 index_sequence<_Is..., _Js>{}, __ls...)...); 520 } 521 522 template <class _Fp, class... _Vs> 523 inline _LIBCPP_INLINE_VISIBILITY 524 static constexpr auto __make_fmatrix() { 525 return __make_fmatrix_impl<_Fp, _Vs...>( 526 index_sequence<>{}, make_index_sequence<decay_t<_Vs>::__size()>{}...); 527 } 528 }; 529 530 struct __variant { 531 template <class _Visitor, class... _Vs> 532 inline _LIBCPP_INLINE_VISIBILITY 533 static constexpr decltype(auto) 534 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 535 return __base::__visit_alt_at(__index, 536 _VSTD::forward<_Visitor>(__visitor), 537 _VSTD::forward<_Vs>(__vs).__impl...); 538 } 539 540 template <class _Visitor, class... _Vs> 541 inline _LIBCPP_INLINE_VISIBILITY 542 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 543 _Vs&&... __vs) { 544 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor), 545 _VSTD::forward<_Vs>(__vs).__impl...); 546 } 547 548 template <class _Visitor, class... _Vs> 549 inline _LIBCPP_INLINE_VISIBILITY 550 static constexpr decltype(auto) 551 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 552 return __visit_alt_at( 553 __index, 554 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 555 _VSTD::forward<_Vs>(__vs)...); 556 } 557 558 template <class _Visitor, class... _Vs> 559 inline _LIBCPP_INLINE_VISIBILITY 560 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, 561 _Vs&&... __vs) { 562 return __visit_alt( 563 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 564 _VSTD::forward<_Vs>(__vs)...); 565 } 566 567 private: 568 template <class _Visitor, class... _Values> 569 static constexpr void __std_visit_exhaustive_visitor_check() { 570 static_assert(is_callable_v<_Visitor(_Values...)>, 571 "`std::visit` requires the visitor to be exhaustive."); 572 } 573 574 template <class _Visitor> 575 struct __value_visitor { 576 template <class... _Alts> 577 inline _LIBCPP_INLINE_VISIBILITY 578 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 579 __std_visit_exhaustive_visitor_check< 580 _Visitor, 581 decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 582 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 583 _VSTD::forward<_Alts>(__alts).__value...); 584 } 585 _Visitor&& __visitor; 586 }; 587 588 template <class _Visitor> 589 inline _LIBCPP_INLINE_VISIBILITY 590 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 591 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)}; 592 } 593 }; 594 595 } // namespace __visitation 596 597 template <size_t _Index, class _Tp> 598 struct _LIBCPP_TEMPLATE_VIS __alt { 599 using __value_type = _Tp; 600 601 template <class... _Args> 602 inline _LIBCPP_INLINE_VISIBILITY 603 explicit constexpr __alt(in_place_t, _Args&&... __args) 604 : __value(_VSTD::forward<_Args>(__args)...) {} 605 606 __value_type __value; 607 }; 608 609 template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 610 union _LIBCPP_TEMPLATE_VIS __union; 611 612 template <_Trait _DestructibleTrait, size_t _Index> 613 union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 614 615 #define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 616 template <size_t _Index, class _Tp, class... _Types> \ 617 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 618 _Index, \ 619 _Tp, \ 620 _Types...> { \ 621 public: \ 622 inline _LIBCPP_INLINE_VISIBILITY \ 623 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 624 \ 625 template <class... _Args> \ 626 inline _LIBCPP_INLINE_VISIBILITY \ 627 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 628 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \ 629 \ 630 template <size_t _Ip, class... _Args> \ 631 inline _LIBCPP_INLINE_VISIBILITY \ 632 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 633 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \ 634 \ 635 __union(const __union&) = default; \ 636 __union(__union&&) = default; \ 637 \ 638 destructor \ 639 \ 640 __union& operator=(const __union&) = default; \ 641 __union& operator=(__union&&) = default; \ 642 \ 643 private: \ 644 char __dummy; \ 645 __alt<_Index, _Tp> __head; \ 646 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 647 \ 648 friend struct __access::__union; \ 649 } 650 651 _LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 652 _LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 653 _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 654 655 #undef _LIBCPP_VARIANT_UNION 656 657 template <_Trait _DestructibleTrait, class... _Types> 658 class _LIBCPP_TEMPLATE_VIS __base { 659 public: 660 inline _LIBCPP_INLINE_VISIBILITY 661 explicit constexpr __base(__valueless_t tag) noexcept 662 : __data(tag), __index(__variant_npos) {} 663 664 template <size_t _Ip, class... _Args> 665 inline _LIBCPP_INLINE_VISIBILITY 666 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 667 : 668 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...), 669 __index(_Ip) {} 670 671 inline _LIBCPP_INLINE_VISIBILITY 672 constexpr bool valueless_by_exception() const noexcept { 673 return index() == variant_npos; 674 } 675 676 inline _LIBCPP_INLINE_VISIBILITY 677 constexpr size_t index() const noexcept { 678 return __index == __variant_npos ? variant_npos : __index; 679 } 680 681 protected: 682 inline _LIBCPP_INLINE_VISIBILITY 683 constexpr auto&& __as_base() & { return *this; } 684 685 inline _LIBCPP_INLINE_VISIBILITY 686 constexpr auto&& __as_base() && { return _VSTD::move(*this); } 687 688 inline _LIBCPP_INLINE_VISIBILITY 689 constexpr auto&& __as_base() const & { return *this; } 690 691 inline _LIBCPP_INLINE_VISIBILITY 692 constexpr auto&& __as_base() const && { return _VSTD::move(*this); } 693 694 inline _LIBCPP_INLINE_VISIBILITY 695 static constexpr size_t __size() { return sizeof...(_Types); } 696 697 __union<_DestructibleTrait, 0, _Types...> __data; 698 unsigned int __index; 699 700 friend struct __access::__base; 701 friend struct __visitation::__base; 702 }; 703 704 template <class _Traits, _Trait = _Traits::__destructible_trait> 705 class _LIBCPP_TEMPLATE_VIS __destructor; 706 707 #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 708 template <class... _Types> \ 709 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \ 710 destructible_trait> \ 711 : public __base<destructible_trait, _Types...> { \ 712 using __base_type = __base<destructible_trait, _Types...>; \ 713 \ 714 public: \ 715 using __base_type::__base_type; \ 716 using __base_type::operator=; \ 717 \ 718 __destructor(const __destructor&) = default; \ 719 __destructor(__destructor&&) = default; \ 720 destructor \ 721 __destructor& operator=(const __destructor&) = default; \ 722 __destructor& operator=(__destructor&&) = default; \ 723 \ 724 protected: \ 725 inline _LIBCPP_INLINE_VISIBILITY \ 726 destroy \ 727 } 728 729 _LIBCPP_VARIANT_DESTRUCTOR( 730 _Trait::_TriviallyAvailable, 731 ~__destructor() = default;, 732 void __destroy() noexcept { this->__index = __variant_npos; }); 733 734 _LIBCPP_VARIANT_DESTRUCTOR( 735 _Trait::_Available, 736 ~__destructor() { __destroy(); }, 737 void __destroy() noexcept { 738 if (!this->valueless_by_exception()) { 739 __visitation::__base::__visit_alt( 740 [](auto& __alt) noexcept { 741 using __alt_type = decay_t<decltype(__alt)>; 742 __alt.~__alt_type(); 743 }, 744 *this); 745 } 746 this->__index = __variant_npos; 747 }); 748 749 _LIBCPP_VARIANT_DESTRUCTOR( 750 _Trait::_Unavailable, 751 ~__destructor() = delete;, 752 void __destroy() noexcept = delete;); 753 754 #undef _LIBCPP_VARIANT_DESTRUCTOR 755 756 template <class _Traits> 757 class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> { 758 using __base_type = __destructor<_Traits>; 759 760 public: 761 using __base_type::__base_type; 762 using __base_type::operator=; 763 764 protected: 765 template <size_t _Ip, class _Tp, class... _Args> 766 inline _LIBCPP_INLINE_VISIBILITY 767 static void __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 768 ::new (_VSTD::addressof(__a)) 769 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); 770 } 771 772 template <class _Rhs> 773 inline _LIBCPP_INLINE_VISIBILITY 774 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) { 775 __lhs.__destroy(); 776 if (!__rhs.valueless_by_exception()) { 777 __visitation::__base::__visit_alt_at( 778 __rhs.index(), 779 [](auto& __lhs_alt, auto&& __rhs_alt) { 780 __construct_alt( 781 __lhs_alt, 782 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 783 }, 784 __lhs, _VSTD::forward<_Rhs>(__rhs)); 785 __lhs.__index = __rhs.index(); 786 } 787 } 788 }; 789 790 template <class _Traits, _Trait = _Traits::__move_constructible_trait> 791 class _LIBCPP_TEMPLATE_VIS __move_constructor; 792 793 #define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 794 move_constructor) \ 795 template <class... _Types> \ 796 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 797 move_constructible_trait> \ 798 : public __constructor<__traits<_Types...>> { \ 799 using __base_type = __constructor<__traits<_Types...>>; \ 800 \ 801 public: \ 802 using __base_type::__base_type; \ 803 using __base_type::operator=; \ 804 \ 805 __move_constructor(const __move_constructor&) = default; \ 806 move_constructor \ 807 ~__move_constructor() = default; \ 808 __move_constructor& operator=(const __move_constructor&) = default; \ 809 __move_constructor& operator=(__move_constructor&&) = default; \ 810 } 811 812 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 813 _Trait::_TriviallyAvailable, 814 __move_constructor(__move_constructor&& __that) = default;); 815 816 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 817 _Trait::_Available, 818 __move_constructor(__move_constructor&& __that) noexcept( 819 __all<is_nothrow_move_constructible_v<_Types>...>::value) 820 : __move_constructor(__valueless_t{}) { 821 this->__generic_construct(*this, _VSTD::move(__that)); 822 }); 823 824 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 825 _Trait::_Unavailable, 826 __move_constructor(__move_constructor&&) = delete;); 827 828 #undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 829 830 template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 831 class _LIBCPP_TEMPLATE_VIS __copy_constructor; 832 833 #define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 834 copy_constructor) \ 835 template <class... _Types> \ 836 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 837 copy_constructible_trait> \ 838 : public __move_constructor<__traits<_Types...>> { \ 839 using __base_type = __move_constructor<__traits<_Types...>>; \ 840 \ 841 public: \ 842 using __base_type::__base_type; \ 843 using __base_type::operator=; \ 844 \ 845 copy_constructor \ 846 __copy_constructor(__copy_constructor&&) = default; \ 847 ~__copy_constructor() = default; \ 848 __copy_constructor& operator=(const __copy_constructor&) = default; \ 849 __copy_constructor& operator=(__copy_constructor&&) = default; \ 850 } 851 852 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 853 _Trait::_TriviallyAvailable, 854 __copy_constructor(const __copy_constructor& __that) = default;); 855 856 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 857 _Trait::_Available, 858 __copy_constructor(const __copy_constructor& __that) 859 : __copy_constructor(__valueless_t{}) { 860 this->__generic_construct(*this, __that); 861 }); 862 863 _LIBCPP_VARIANT_COPY_CONSTRUCTOR( 864 _Trait::_Unavailable, 865 __copy_constructor(const __copy_constructor&) = delete;); 866 867 #undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 868 869 template <class _Traits> 870 class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 871 using __base_type = __copy_constructor<_Traits>; 872 873 public: 874 using __base_type::__base_type; 875 using __base_type::operator=; 876 877 template <size_t _Ip, class... _Args> 878 inline _LIBCPP_INLINE_VISIBILITY 879 void __emplace(_Args&&... __args) { 880 this->__destroy(); 881 this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 882 _VSTD::forward<_Args>(__args)...); 883 this->__index = _Ip; 884 } 885 886 protected: 887 template <bool _CopyAssign, size_t _Ip, class _Tp, class _Arg> 888 inline _LIBCPP_INLINE_VISIBILITY 889 void __assign_alt(__alt<_Ip, _Tp>& __a, 890 _Arg&& __arg, 891 bool_constant<_CopyAssign> __tag) { 892 if (this->index() == _Ip) { 893 __a.__value = _VSTD::forward<_Arg>(__arg); 894 } else { 895 struct { 896 void operator()(true_type) const { 897 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg))); 898 } 899 void operator()(false_type) const { 900 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg)); 901 } 902 __assignment* __this; 903 _Arg&& __arg; 904 } __impl{this, _VSTD::forward<_Arg>(__arg)}; 905 __impl(__tag); 906 } 907 } 908 909 template <class _That> 910 inline _LIBCPP_INLINE_VISIBILITY 911 void __generic_assign(_That&& __that) { 912 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 913 // do nothing. 914 } else if (__that.valueless_by_exception()) { 915 this->__destroy(); 916 } else { 917 __visitation::__base::__visit_alt_at( 918 __that.index(), 919 [this](auto& __this_alt, auto&& __that_alt) { 920 this->__assign_alt( 921 __this_alt, 922 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value, 923 is_lvalue_reference<_That>{}); 924 }, 925 *this, _VSTD::forward<_That>(__that)); 926 } 927 } 928 }; 929 930 template <class _Traits, _Trait = _Traits::__move_assignable_trait> 931 class _LIBCPP_TEMPLATE_VIS __move_assignment; 932 933 #define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 934 move_assignment) \ 935 template <class... _Types> \ 936 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 937 move_assignable_trait> \ 938 : public __assignment<__traits<_Types...>> { \ 939 using __base_type = __assignment<__traits<_Types...>>; \ 940 \ 941 public: \ 942 using __base_type::__base_type; \ 943 using __base_type::operator=; \ 944 \ 945 __move_assignment(const __move_assignment&) = default; \ 946 __move_assignment(__move_assignment&&) = default; \ 947 ~__move_assignment() = default; \ 948 __move_assignment& operator=(const __move_assignment&) = default; \ 949 move_assignment \ 950 } 951 952 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 953 _Trait::_TriviallyAvailable, 954 __move_assignment& operator=(__move_assignment&& __that) = default;); 955 956 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 957 _Trait::_Available, 958 __move_assignment& operator=(__move_assignment&& __that) noexcept( 959 __all<(is_nothrow_move_constructible_v<_Types> && 960 is_nothrow_move_assignable_v<_Types>)...>::value) { 961 this->__generic_assign(_VSTD::move(__that)); 962 return *this; 963 }); 964 965 _LIBCPP_VARIANT_MOVE_ASSIGNMENT( 966 _Trait::_Unavailable, 967 __move_assignment& operator=(__move_assignment&&) = delete;); 968 969 #undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 970 971 template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 972 class _LIBCPP_TEMPLATE_VIS __copy_assignment; 973 974 #define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 975 copy_assignment) \ 976 template <class... _Types> \ 977 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 978 copy_assignable_trait> \ 979 : public __move_assignment<__traits<_Types...>> { \ 980 using __base_type = __move_assignment<__traits<_Types...>>; \ 981 \ 982 public: \ 983 using __base_type::__base_type; \ 984 using __base_type::operator=; \ 985 \ 986 __copy_assignment(const __copy_assignment&) = default; \ 987 __copy_assignment(__copy_assignment&&) = default; \ 988 ~__copy_assignment() = default; \ 989 copy_assignment \ 990 __copy_assignment& operator=(__copy_assignment&&) = default; \ 991 } 992 993 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 994 _Trait::_TriviallyAvailable, 995 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 996 997 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 998 _Trait::_Available, 999 __copy_assignment& operator=(const __copy_assignment& __that) { 1000 this->__generic_assign(__that); 1001 return *this; 1002 }); 1003 1004 _LIBCPP_VARIANT_COPY_ASSIGNMENT( 1005 _Trait::_Unavailable, 1006 __copy_assignment& operator=(const __copy_assignment&) = delete;); 1007 1008 #undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1009 1010 template <class... _Types> 1011 class _LIBCPP_TEMPLATE_VIS __impl 1012 : public __copy_assignment<__traits<_Types...>> { 1013 using __base_type = __copy_assignment<__traits<_Types...>>; 1014 1015 public: 1016 using __base_type::__base_type; 1017 using __base_type::operator=; 1018 1019 template <size_t _Ip, class _Arg> 1020 inline _LIBCPP_INLINE_VISIBILITY 1021 void __assign(_Arg&& __arg) { 1022 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1023 _VSTD::forward<_Arg>(__arg), 1024 false_type{}); 1025 } 1026 1027 inline _LIBCPP_INLINE_VISIBILITY 1028 void __swap(__impl& __that) { 1029 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1030 // do nothing. 1031 } else if (this->index() == __that.index()) { 1032 __visitation::__base::__visit_alt_at( 1033 this->index(), 1034 [](auto& __this_alt, auto& __that_alt) { 1035 using _VSTD::swap; 1036 swap(__this_alt.__value, __that_alt.__value); 1037 }, 1038 *this, 1039 __that); 1040 } else { 1041 __impl* __lhs = this; 1042 __impl* __rhs = _VSTD::addressof(__that); 1043 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1044 _VSTD::swap(__lhs, __rhs); 1045 } 1046 __impl __tmp(_VSTD::move(*__rhs)); 1047 #ifndef _LIBCPP_NO_EXCEPTIONS 1048 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1049 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1050 // into `__rhs` and provide the strong exception safety guarentee. 1051 try { 1052 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1053 } catch (...) { 1054 if (__tmp.__move_nothrow()) { 1055 this->__generic_construct(*__rhs, _VSTD::move(__tmp)); 1056 } 1057 throw; 1058 } 1059 #else 1060 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1061 #endif 1062 this->__generic_construct(*__lhs, _VSTD::move(__tmp)); 1063 } 1064 } 1065 1066 private: 1067 inline _LIBCPP_INLINE_VISIBILITY 1068 bool __move_nothrow() const { 1069 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1070 return this->valueless_by_exception() || __results[this->index()]; 1071 } 1072 }; 1073 1074 template <class... _Types> 1075 struct __overload; 1076 1077 template <> 1078 struct __overload<> { void operator()() const; }; 1079 1080 template <class _Tp, class... _Types> 1081 struct __overload<_Tp, _Types...> : __overload<_Types...> { 1082 using __overload<_Types...>::operator(); 1083 __identity<_Tp> operator()(_Tp) const; 1084 }; 1085 1086 template <class _Tp, class... _Types> 1087 using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type; 1088 1089 } // __variant_detail 1090 1091 template <class... _Types> 1092 class _LIBCPP_TEMPLATE_VIS variant 1093 : private __sfinae_ctor_base< 1094 __all<is_copy_constructible_v<_Types>...>::value, 1095 __all<is_move_constructible_v<_Types>...>::value>, 1096 private __sfinae_assign_base< 1097 __all<(is_copy_constructible_v<_Types> && 1098 is_move_constructible_v<_Types> && 1099 is_copy_assignable_v<_Types>)...>::value, 1100 __all<(is_move_constructible_v<_Types> && 1101 is_move_assignable_v<_Types>)...>::value> { 1102 static_assert(0 < sizeof...(_Types), 1103 "variant must consist of at least one alternative."); 1104 1105 static_assert(__all<!is_array_v<_Types>...>::value, 1106 "variant can not have an array type as an alternative."); 1107 1108 static_assert(__all<!is_reference_v<_Types>...>::value, 1109 "variant can not have a reference type as an alternative."); 1110 1111 static_assert(__all<!is_void_v<_Types>...>::value, 1112 "variant can not have a void type as an alternative."); 1113 1114 using __first_type = variant_alternative_t<0, variant>; 1115 1116 public: 1117 template <bool _Dummy = true, 1118 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1119 _Dummy>::value, 1120 int> = 0> 1121 inline _LIBCPP_INLINE_VISIBILITY 1122 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1123 : __impl(in_place_index<0>) {} 1124 1125 variant(const variant&) = default; 1126 variant(variant&&) = default; 1127 1128 template < 1129 class _Arg, 1130 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0, 1131 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1132 size_t _Ip = 1133 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1134 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1135 inline _LIBCPP_INLINE_VISIBILITY 1136 constexpr variant(_Arg&& __arg) noexcept( 1137 is_nothrow_constructible_v<_Tp, _Arg>) 1138 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {} 1139 1140 template <size_t _Ip, class... _Args, 1141 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1142 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1143 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1144 inline _LIBCPP_INLINE_VISIBILITY 1145 explicit constexpr variant( 1146 in_place_index_t<_Ip>, 1147 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1148 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1149 1150 template < 1151 size_t _Ip, 1152 class _Up, 1153 class... _Args, 1154 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1155 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1156 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1157 int> = 0> 1158 inline _LIBCPP_INLINE_VISIBILITY 1159 explicit constexpr variant( 1160 in_place_index_t<_Ip>, 1161 initializer_list<_Up> __il, 1162 _Args&&... __args) noexcept( 1163 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1164 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1165 1166 template < 1167 class _Tp, 1168 class... _Args, 1169 size_t _Ip = 1170 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1171 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1172 inline _LIBCPP_INLINE_VISIBILITY 1173 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1174 is_nothrow_constructible_v<_Tp, _Args...>) 1175 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1176 1177 template < 1178 class _Tp, 1179 class _Up, 1180 class... _Args, 1181 size_t _Ip = 1182 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1183 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1184 int> = 0> 1185 inline _LIBCPP_INLINE_VISIBILITY 1186 explicit constexpr variant( 1187 in_place_type_t<_Tp>, 1188 initializer_list<_Up> __il, 1189 _Args&&... __args) noexcept( 1190 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1191 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1192 1193 ~variant() = default; 1194 1195 variant& operator=(const variant&) = default; 1196 variant& operator=(variant&&) = default; 1197 1198 template < 1199 class _Arg, 1200 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0, 1201 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1202 size_t _Ip = 1203 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1204 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1205 int> = 0> 1206 inline _LIBCPP_INLINE_VISIBILITY 1207 variant& operator=(_Arg&& __arg) noexcept( 1208 is_nothrow_assignable_v<_Tp&, _Arg> && 1209 is_nothrow_constructible_v<_Tp, _Arg>) { 1210 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg)); 1211 return *this; 1212 } 1213 1214 template < 1215 size_t _Ip, 1216 class... _Args, 1217 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1218 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1219 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1220 inline _LIBCPP_INLINE_VISIBILITY 1221 void emplace(_Args&&... __args) { 1222 __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1223 } 1224 1225 template < 1226 size_t _Ip, 1227 class _Up, 1228 class... _Args, 1229 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1230 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1231 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1232 int> = 0> 1233 inline _LIBCPP_INLINE_VISIBILITY 1234 void emplace(initializer_list<_Up> __il, _Args&&... __args) { 1235 __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1236 } 1237 1238 template < 1239 class _Tp, 1240 class... _Args, 1241 size_t _Ip = 1242 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1243 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1244 inline _LIBCPP_INLINE_VISIBILITY 1245 void emplace(_Args&&... __args) { 1246 __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1247 } 1248 1249 template < 1250 class _Tp, 1251 class _Up, 1252 class... _Args, 1253 size_t _Ip = 1254 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1255 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1256 int> = 0> 1257 inline _LIBCPP_INLINE_VISIBILITY 1258 void emplace(initializer_list<_Up> __il, _Args&&... __args) { 1259 __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1260 } 1261 1262 inline _LIBCPP_INLINE_VISIBILITY 1263 constexpr bool valueless_by_exception() const noexcept { 1264 return __impl.valueless_by_exception(); 1265 } 1266 1267 inline _LIBCPP_INLINE_VISIBILITY 1268 constexpr size_t index() const noexcept { return __impl.index(); } 1269 1270 template < 1271 bool _Dummy = true, 1272 enable_if_t< 1273 __all<( 1274 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1275 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1276 int> = 0> 1277 inline _LIBCPP_INLINE_VISIBILITY 1278 void swap(variant& __that) noexcept( 1279 __all<(is_nothrow_move_constructible_v<_Types> && 1280 is_nothrow_swappable_v<_Types>)...>::value) { 1281 __impl.__swap(__that.__impl); 1282 } 1283 1284 private: 1285 __variant_detail::__impl<_Types...> __impl; 1286 1287 friend struct __variant_detail::__access::__variant; 1288 friend struct __variant_detail::__visitation::__variant; 1289 }; 1290 1291 template <size_t _Ip, class... _Types> 1292 inline _LIBCPP_INLINE_VISIBILITY 1293 constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1294 return __v.index() == _Ip; 1295 } 1296 1297 template <class _Tp, class... _Types> 1298 inline _LIBCPP_INLINE_VISIBILITY 1299 constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1300 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1301 } 1302 1303 template <size_t _Ip, class _Vp> 1304 inline _LIBCPP_INLINE_VISIBILITY 1305 static constexpr auto&& __generic_get(_Vp&& __v) { 1306 using __variant_detail::__access::__variant; 1307 if (!__holds_alternative<_Ip>(__v)) { 1308 __throw_bad_variant_access(); 1309 } 1310 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1311 } 1312 1313 template <size_t _Ip, class... _Types> 1314 inline _LIBCPP_INLINE_VISIBILITY 1315 constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1316 variant<_Types...>& __v) { 1317 static_assert(_Ip < sizeof...(_Types)); 1318 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1319 return __generic_get<_Ip>(__v); 1320 } 1321 1322 template <size_t _Ip, class... _Types> 1323 inline _LIBCPP_INLINE_VISIBILITY 1324 constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1325 variant<_Types...>&& __v) { 1326 static_assert(_Ip < sizeof...(_Types)); 1327 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1328 return __generic_get<_Ip>(_VSTD::move(__v)); 1329 } 1330 1331 template <size_t _Ip, class... _Types> 1332 inline _LIBCPP_INLINE_VISIBILITY 1333 constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1334 const variant<_Types...>& __v) { 1335 static_assert(_Ip < sizeof...(_Types)); 1336 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1337 return __generic_get<_Ip>(__v); 1338 } 1339 1340 template <size_t _Ip, class... _Types> 1341 inline _LIBCPP_INLINE_VISIBILITY 1342 constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1343 const variant<_Types...>&& __v) { 1344 static_assert(_Ip < sizeof...(_Types)); 1345 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1346 return __generic_get<_Ip>(_VSTD::move(__v)); 1347 } 1348 1349 template <class _Tp, class... _Types> 1350 inline _LIBCPP_INLINE_VISIBILITY 1351 constexpr _Tp& get(variant<_Types...>& __v) { 1352 static_assert(!is_void_v<_Tp>); 1353 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1354 } 1355 1356 template <class _Tp, class... _Types> 1357 inline _LIBCPP_INLINE_VISIBILITY 1358 constexpr _Tp&& get(variant<_Types...>&& __v) { 1359 static_assert(!is_void_v<_Tp>); 1360 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1361 _VSTD::move(__v)); 1362 } 1363 1364 template <class _Tp, class... _Types> 1365 inline _LIBCPP_INLINE_VISIBILITY 1366 constexpr const _Tp& get(const variant<_Types...>& __v) { 1367 static_assert(!is_void_v<_Tp>); 1368 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1369 } 1370 1371 template <class _Tp, class... _Types> 1372 inline _LIBCPP_INLINE_VISIBILITY 1373 constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1374 static_assert(!is_void_v<_Tp>); 1375 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1376 _VSTD::move(__v)); 1377 } 1378 1379 template <size_t _Ip, class _Vp> 1380 inline _LIBCPP_INLINE_VISIBILITY 1381 constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1382 using __variant_detail::__access::__variant; 1383 return __v && __holds_alternative<_Ip>(*__v) 1384 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1385 : nullptr; 1386 } 1387 1388 template <size_t _Ip, class... _Types> 1389 inline _LIBCPP_INLINE_VISIBILITY 1390 constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1391 get_if(variant<_Types...>* __v) noexcept { 1392 static_assert(_Ip < sizeof...(_Types)); 1393 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1394 return __generic_get_if<_Ip>(__v); 1395 } 1396 1397 template <size_t _Ip, class... _Types> 1398 inline _LIBCPP_INLINE_VISIBILITY 1399 constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1400 get_if(const variant<_Types...>* __v) noexcept { 1401 static_assert(_Ip < sizeof...(_Types)); 1402 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1403 return __generic_get_if<_Ip>(__v); 1404 } 1405 1406 template <class _Tp, class... _Types> 1407 inline _LIBCPP_INLINE_VISIBILITY 1408 constexpr add_pointer_t<_Tp> 1409 get_if(variant<_Types...>* __v) noexcept { 1410 static_assert(!is_void_v<_Tp>); 1411 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1412 } 1413 1414 template <class _Tp, class... _Types> 1415 inline _LIBCPP_INLINE_VISIBILITY 1416 constexpr add_pointer_t<const _Tp> 1417 get_if(const variant<_Types...>* __v) noexcept { 1418 static_assert(!is_void_v<_Tp>); 1419 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 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 false; 1428 if (__lhs.valueless_by_exception()) return true; 1429 return __variant::__visit_value_at(__lhs.index(), equal_to<>{}, __lhs, __rhs); 1430 } 1431 1432 template <class... _Types> 1433 inline _LIBCPP_INLINE_VISIBILITY 1434 constexpr bool operator!=(const variant<_Types...>& __lhs, 1435 const variant<_Types...>& __rhs) { 1436 using __variant_detail::__visitation::__variant; 1437 if (__lhs.index() != __rhs.index()) return true; 1438 if (__lhs.valueless_by_exception()) return false; 1439 return __variant::__visit_value_at( 1440 __lhs.index(), not_equal_to<>{}, __lhs, __rhs); 1441 } 1442 1443 template <class... _Types> 1444 inline _LIBCPP_INLINE_VISIBILITY 1445 constexpr bool operator<(const variant<_Types...>& __lhs, 1446 const variant<_Types...>& __rhs) { 1447 using __variant_detail::__visitation::__variant; 1448 if (__rhs.valueless_by_exception()) return false; 1449 if (__lhs.valueless_by_exception()) return true; 1450 if (__lhs.index() < __rhs.index()) return true; 1451 if (__lhs.index() > __rhs.index()) return false; 1452 return __variant::__visit_value_at(__lhs.index(), less<>{}, __lhs, __rhs); 1453 } 1454 1455 template <class... _Types> 1456 inline _LIBCPP_INLINE_VISIBILITY 1457 constexpr bool operator>(const variant<_Types...>& __lhs, 1458 const variant<_Types...>& __rhs) { 1459 using __variant_detail::__visitation::__variant; 1460 if (__lhs.valueless_by_exception()) return false; 1461 if (__rhs.valueless_by_exception()) return true; 1462 if (__lhs.index() > __rhs.index()) return true; 1463 if (__lhs.index() < __rhs.index()) return false; 1464 return __variant::__visit_value_at(__lhs.index(), greater<>{}, __lhs, __rhs); 1465 } 1466 1467 template <class... _Types> 1468 inline _LIBCPP_INLINE_VISIBILITY 1469 constexpr bool operator<=(const variant<_Types...>& __lhs, 1470 const variant<_Types...>& __rhs) { 1471 using __variant_detail::__visitation::__variant; 1472 if (__lhs.valueless_by_exception()) return true; 1473 if (__rhs.valueless_by_exception()) return false; 1474 if (__lhs.index() < __rhs.index()) return true; 1475 if (__lhs.index() > __rhs.index()) return false; 1476 return __variant::__visit_value_at( 1477 __lhs.index(), less_equal<>{}, __lhs, __rhs); 1478 } 1479 1480 template <class... _Types> 1481 inline _LIBCPP_INLINE_VISIBILITY 1482 constexpr bool operator>=(const variant<_Types...>& __lhs, 1483 const variant<_Types...>& __rhs) { 1484 using __variant_detail::__visitation::__variant; 1485 if (__rhs.valueless_by_exception()) return true; 1486 if (__lhs.valueless_by_exception()) return false; 1487 if (__lhs.index() > __rhs.index()) return true; 1488 if (__lhs.index() < __rhs.index()) return false; 1489 return __variant::__visit_value_at( 1490 __lhs.index(), greater_equal<>{}, __lhs, __rhs); 1491 } 1492 1493 template <class _Visitor, class... _Vs> 1494 inline _LIBCPP_INLINE_VISIBILITY 1495 constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1496 using __variant_detail::__visitation::__variant; 1497 bool __results[] = {__vs.valueless_by_exception()...}; 1498 for (bool __result : __results) { 1499 if (__result) { 1500 __throw_bad_variant_access(); 1501 } 1502 } 1503 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor), 1504 _VSTD::forward<_Vs>(__vs)...); 1505 } 1506 1507 struct _LIBCPP_TEMPLATE_VIS monostate {}; 1508 1509 inline _LIBCPP_INLINE_VISIBILITY 1510 constexpr bool operator<(monostate, monostate) noexcept { return false; } 1511 1512 inline _LIBCPP_INLINE_VISIBILITY 1513 constexpr bool operator>(monostate, monostate) noexcept { return false; } 1514 1515 inline _LIBCPP_INLINE_VISIBILITY 1516 constexpr bool operator<=(monostate, monostate) noexcept { return true; } 1517 1518 inline _LIBCPP_INLINE_VISIBILITY 1519 constexpr bool operator>=(monostate, monostate) noexcept { return true; } 1520 1521 inline _LIBCPP_INLINE_VISIBILITY 1522 constexpr bool operator==(monostate, monostate) noexcept { return true; } 1523 1524 inline _LIBCPP_INLINE_VISIBILITY 1525 constexpr bool operator!=(monostate, monostate) noexcept { return false; } 1526 1527 template <class... _Types> 1528 inline _LIBCPP_INLINE_VISIBILITY 1529 auto swap(variant<_Types...>& __lhs, 1530 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1531 -> decltype(__lhs.swap(__rhs)) { 1532 __lhs.swap(__rhs); 1533 } 1534 1535 template <class... _Types> 1536 struct _LIBCPP_TEMPLATE_VIS hash< 1537 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1538 using argument_type = variant<_Types...>; 1539 using result_type = size_t; 1540 1541 inline _LIBCPP_INLINE_VISIBILITY 1542 result_type operator()(const argument_type& __v) const { 1543 using __variant_detail::__visitation::__variant; 1544 size_t __res = 1545 __v.valueless_by_exception() 1546 ? 299792458 // Random value chosen by the universe upon creation 1547 : __variant::__visit_alt( 1548 [](const auto& __alt) { 1549 using __alt_type = decay_t<decltype(__alt)>; 1550 using __value_type = remove_const_t< 1551 typename __alt_type::__value_type>; 1552 return hash<__value_type>{}(__alt.__value); 1553 }, 1554 __v); 1555 return __hash_combine(__res, hash<size_t>{}(__v.index())); 1556 } 1557 }; 1558 1559 template <> 1560 struct _LIBCPP_TEMPLATE_VIS hash<monostate> { 1561 using argument_type = monostate; 1562 using result_type = size_t; 1563 1564 inline _LIBCPP_INLINE_VISIBILITY 1565 result_type operator()(const argument_type&) const { 1566 return 66740831; // return a fundamentally attractive random value. 1567 } 1568 }; 1569 1570 #endif // _LIBCPP_STD_VER > 14 1571 1572 _LIBCPP_END_NAMESPACE_STD 1573 1574 #endif // _LIBCPP_VARIANT 1575
