2 //===------------------------------ variant -------------------------------===//
4 // The LLVM Compiler Infrastructure
6 // This file is dual licensed under the MIT and the University of Illinois Open
7 // Source Licenses. See LICENSE.TXT for details.
9 //===----------------------------------------------------------------------===//
11 #ifndef _LIBCPP_VARIANT
12 #define _LIBCPP_VARIANT
19 // 20.7.2, class template variant
20 template <class... Types>
24 // 20.7.2.1, constructors
25 constexpr variant() noexcept(see below);
26 variant(const variant&);
27 variant(variant&&) noexcept(see below);
29 template <class T> constexpr variant(T&&) noexcept(see below);
31 template <class T, class... Args>
32 constexpr explicit variant(in_place_type_t<T>, Args&&...);
34 template <class T, class U, class... Args>
35 constexpr explicit variant(
36 in_place_type_t<T>, initializer_list<U>, Args&&...);
38 template <size_t I, class... Args>
39 constexpr explicit variant(in_place_index_t<I>, Args&&...);
41 template <size_t I, class U, class... Args>
42 constexpr explicit variant(
43 in_place_index_t<I>, initializer_list<U>, Args&&...);
45 // 20.7.2.2, destructor
48 // 20.7.2.3, assignment
49 variant& operator=(const variant&);
50 variant& operator=(variant&&) noexcept(see below);
52 template <class T> variant& operator=(T&&) noexcept(see below);
54 // 20.7.2.4, modifiers
55 template <class T, class... Args>
56 T& emplace(Args&&...);
58 template <class T, class U, class... Args>
59 T& emplace(initializer_list<U>, Args&&...);
61 template <size_t I, class... Args>
62 variant_alternative_t<I, variant>& emplace(Args&&...);
64 template <size_t I, class U, class... Args>
65 variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...);
67 // 20.7.2.5, value status
68 constexpr bool valueless_by_exception() const noexcept;
69 constexpr size_t index() const noexcept;
72 void swap(variant&) noexcept(see below);
75 // 20.7.3, variant helper classes
76 template <class T> struct variant_size; // undefined
79 constexpr size_t variant_size_v = variant_size<T>::value;
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>;
85 template <class... Types>
86 struct variant_size<variant<Types...>>;
88 template <size_t I, class T> struct variant_alternative; // undefined
90 template <size_t I, class T>
91 using variant_alternative_t = typename variant_alternative<I, T>::type;
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>;
97 template <size_t I, class... Types>
98 struct variant_alternative<I, variant<Types...>>;
100 constexpr size_t variant_npos = -1;
102 // 20.7.4, value access
103 template <class T, class... Types>
104 constexpr bool holds_alternative(const variant<Types...>&) noexcept;
106 template <size_t I, class... Types>
107 constexpr variant_alternative_t<I, variant<Types...>>&
108 get(variant<Types...>&);
110 template <size_t I, class... Types>
111 constexpr variant_alternative_t<I, variant<Types...>>&&
112 get(variant<Types...>&&);
114 template <size_t I, class... Types>
115 constexpr variant_alternative_t<I, variant<Types...>> const&
116 get(const variant<Types...>&);
118 template <size_t I, class... Types>
119 constexpr variant_alternative_t<I, variant<Types...>> const&&
120 get(const variant<Types...>&&);
122 template <class T, class... Types>
123 constexpr T& get(variant<Types...>&);
125 template <class T, class... Types>
126 constexpr T&& get(variant<Types...>&&);
128 template <class T, class... Types>
129 constexpr const T& get(const variant<Types...>&);
131 template <class T, class... Types>
132 constexpr const T&& get(const variant<Types...>&&);
134 template <size_t I, class... Types>
135 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
136 get_if(variant<Types...>*) noexcept;
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;
142 template <class T, class... Types>
143 constexpr add_pointer_t<T>
144 get_if(variant<Types...>*) noexcept;
146 template <class T, class... Types>
147 constexpr add_pointer_t<const T>
148 get_if(const variant<Types...>*) noexcept;
150 // 20.7.5, relational operators
151 template <class... Types>
152 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
154 template <class... Types>
155 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
157 template <class... Types>
158 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
160 template <class... Types>
161 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
163 template <class... Types>
164 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
166 template <class... Types>
167 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
169 // 20.7.6, visitation
170 template <class Visitor, class... Variants>
171 constexpr see below visit(Visitor&&, Variants&&...);
173 // 20.7.7, class monostate
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;
184 // 20.7.9, specialized algorithms
185 template <class... Types>
186 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
188 // 20.7.10, class bad_variant_access
189 class bad_variant_access;
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>;
204 #include <functional>
205 #include <initializer_list>
208 #include <type_traits>
211 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
212 #pragma GCC system_header
215 namespace std { // explicitly not using versioning namespace
217 class _LIBCPP_EXCEPTION_ABI bad_variant_access : public exception {
219 virtual const char* what() const _NOEXCEPT;
224 _LIBCPP_BEGIN_NAMESPACE_STD
226 #if _LIBCPP_STD_VER > 14
229 inline _LIBCPP_INLINE_VISIBILITY
230 void __throw_bad_variant_access() {
231 #ifndef _LIBCPP_NO_EXCEPTIONS
232 throw bad_variant_access();
238 template <class... _Types>
239 class _LIBCPP_TEMPLATE_VIS variant;
242 struct _LIBCPP_TEMPLATE_VIS variant_size;
245 constexpr size_t variant_size_v = variant_size<_Tp>::value;
248 struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {};
251 struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {};
254 struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp>
255 : variant_size<_Tp> {};
257 template <class... _Types>
258 struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>>
259 : integral_constant<size_t, sizeof...(_Types)> {};
261 template <size_t _Ip, class _Tp>
262 struct _LIBCPP_TEMPLATE_VIS variant_alternative;
264 template <size_t _Ip, class _Tp>
265 using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
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>> {};
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>> {};
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>> {};
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...>;
285 constexpr size_t variant_npos = static_cast<size_t>(-1);
286 constexpr unsigned int __variant_npos = static_cast<unsigned int>(-1);
288 namespace __find_detail {
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) {
306 template <size_t _Index>
307 struct __find_unambiguous_index_sfinae_impl
308 : integral_constant<size_t, _Index> {};
311 struct __find_unambiguous_index_sfinae_impl<__not_found> {};
314 struct __find_unambiguous_index_sfinae_impl<__ambiguous> {};
316 template <class _Tp, class... _Types>
317 struct __find_unambiguous_index_sfinae
318 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {};
320 } // namespace __find_detail
322 namespace __variant_detail {
324 struct __valueless_t {};
326 enum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
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;
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)) {
347 template <typename... _Types>
349 static constexpr _Trait __copy_constructible_trait =
350 __common_trait({__trait<_Types,
351 is_trivially_copy_constructible,
352 is_copy_constructible>...});
354 static constexpr _Trait __move_constructible_trait =
355 __common_trait({__trait<_Types,
356 is_trivially_move_constructible,
357 is_move_constructible>...});
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>...});
364 static constexpr _Trait __move_assignable_trait = __common_trait(
365 {__move_constructible_trait,
366 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
368 static constexpr _Trait __destructible_trait = __common_trait(
369 {__trait<_Types, is_trivially_destructible, is_destructible>...});
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;
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>);
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>);
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);
405 } // namespace __access
407 namespace __visitation {
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()...);
421 template <class _Visitor, class... _Vs>
422 inline _LIBCPP_INLINE_VISIBILITY
423 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
425 constexpr auto __fmatrix =
426 __make_fmatrix<_Visitor&&,
427 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
428 return __at(__fmatrix, __vs.index()...)(
429 _VSTD::forward<_Visitor>(__visitor),
430 _VSTD::forward<_Vs>(__vs).__as_base()...);
435 inline _LIBCPP_INLINE_VISIBILITY
436 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
438 template <class _Tp, size_t _Np, typename... _Indices>
439 inline _LIBCPP_INLINE_VISIBILITY
440 static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
441 size_t __index, _Indices... __indices) {
442 return __at(__elems[__index], __indices...);
445 template <class _Fp, class... _Fs>
446 static constexpr void __std_visit_visitor_return_type_check() {
448 __all<is_same_v<_Fp, _Fs>...>::value,
449 "`std::visit` requires the visitor to have a single return type.");
452 template <class... _Fs>
453 inline _LIBCPP_INLINE_VISIBILITY
454 static constexpr auto __make_farray(_Fs&&... __fs) {
455 __std_visit_visitor_return_type_check<decay_t<_Fs>...>();
456 using __result = array<common_type_t<decay_t<_Fs>...>, sizeof...(_Fs)>;
457 return __result{{_VSTD::forward<_Fs>(__fs)...}};
460 template <std::size_t... _Is>
461 struct __dispatcher {
462 template <class _Fp, class... _Vs>
463 inline _LIBCPP_INLINE_VISIBILITY
464 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
465 return __invoke_constexpr(
466 static_cast<_Fp>(__f),
467 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
471 template <class _Fp, class... _Vs, size_t... _Is>
472 inline _LIBCPP_INLINE_VISIBILITY
473 static constexpr auto __make_dispatch(index_sequence<_Is...>) {
474 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
477 template <size_t _Ip, class _Fp, class... _Vs>
478 inline _LIBCPP_INLINE_VISIBILITY
479 static constexpr auto __make_fdiagonal_impl() {
480 return __make_dispatch<_Fp, _Vs...>(
481 index_sequence<(__identity<_Vs>{}, _Ip)...>{});
484 template <class _Fp, class... _Vs, size_t... _Is>
485 inline _LIBCPP_INLINE_VISIBILITY
486 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
487 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
490 template <class _Fp, class _Vp, class... _Vs>
491 inline _LIBCPP_INLINE_VISIBILITY
492 static constexpr auto __make_fdiagonal() {
493 constexpr size_t _Np = decay_t<_Vp>::__size();
494 static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value);
495 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
498 template <class _Fp, class... _Vs, size_t... _Is>
499 inline _LIBCPP_INLINE_VISIBILITY
500 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
501 return __make_dispatch<_Fp, _Vs...>(__is);
504 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
505 inline _LIBCPP_INLINE_VISIBILITY
506 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
507 index_sequence<_Js...>,
509 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
510 index_sequence<_Is..., _Js>{}, __ls...)...);
513 template <class _Fp, class... _Vs>
514 inline _LIBCPP_INLINE_VISIBILITY
515 static constexpr auto __make_fmatrix() {
516 return __make_fmatrix_impl<_Fp, _Vs...>(
517 index_sequence<>{}, make_index_sequence<decay_t<_Vs>::__size()>{}...);
522 template <class _Visitor, class... _Vs>
523 inline _LIBCPP_INLINE_VISIBILITY
524 static constexpr decltype(auto)
525 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
526 return __base::__visit_alt_at(__index,
527 _VSTD::forward<_Visitor>(__visitor),
528 _VSTD::forward<_Vs>(__vs).__impl...);
531 template <class _Visitor, class... _Vs>
532 inline _LIBCPP_INLINE_VISIBILITY
533 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
535 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor),
536 _VSTD::forward<_Vs>(__vs).__impl...);
539 template <class _Visitor, class... _Vs>
540 inline _LIBCPP_INLINE_VISIBILITY
541 static constexpr decltype(auto)
542 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
543 return __visit_alt_at(
545 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
546 _VSTD::forward<_Vs>(__vs)...);
549 template <class _Visitor, class... _Vs>
550 inline _LIBCPP_INLINE_VISIBILITY
551 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
554 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
555 _VSTD::forward<_Vs>(__vs)...);
559 template <class _Visitor, class... _Values>
560 static constexpr void __std_visit_exhaustive_visitor_check() {
561 static_assert(is_callable_v<_Visitor(_Values...)>,
562 "`std::visit` requires the visitor to be exhaustive.");
565 template <class _Visitor>
566 struct __value_visitor {
567 template <class... _Alts>
568 inline _LIBCPP_INLINE_VISIBILITY
569 constexpr decltype(auto) operator()(_Alts&&... __alts) const {
570 __std_visit_exhaustive_visitor_check<
572 decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
573 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
574 _VSTD::forward<_Alts>(__alts).__value...);
576 _Visitor&& __visitor;
579 template <class _Visitor>
580 inline _LIBCPP_INLINE_VISIBILITY
581 static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
582 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
586 } // namespace __visitation
588 template <size_t _Index, class _Tp>
589 struct _LIBCPP_TEMPLATE_VIS __alt {
590 using __value_type = _Tp;
592 template <class... _Args>
593 inline _LIBCPP_INLINE_VISIBILITY
594 explicit constexpr __alt(in_place_t, _Args&&... __args)
595 : __value(_VSTD::forward<_Args>(__args)...) {}
597 __value_type __value;
600 template <_Trait _DestructibleTrait, size_t _Index, class... _Types>
601 union _LIBCPP_TEMPLATE_VIS __union;
603 template <_Trait _DestructibleTrait, size_t _Index>
604 union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
606 #define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \
607 template <size_t _Index, class _Tp, class... _Types> \
608 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \
613 inline _LIBCPP_INLINE_VISIBILITY \
614 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \
616 template <class... _Args> \
617 inline _LIBCPP_INLINE_VISIBILITY \
618 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \
619 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \
621 template <size_t _Ip, class... _Args> \
622 inline _LIBCPP_INLINE_VISIBILITY \
623 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \
624 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \
626 __union(const __union&) = default; \
627 __union(__union&&) = default; \
631 __union& operator=(const __union&) = default; \
632 __union& operator=(__union&&) = default; \
636 __alt<_Index, _Tp> __head; \
637 __union<destructible_trait, _Index + 1, _Types...> __tail; \
639 friend struct __access::__union; \
642 _LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
643 _LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
644 _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;);
646 #undef _LIBCPP_VARIANT_UNION
648 template <_Trait _DestructibleTrait, class... _Types>
649 class _LIBCPP_TEMPLATE_VIS __base {
651 inline _LIBCPP_INLINE_VISIBILITY
652 explicit constexpr __base(__valueless_t tag) noexcept
653 : __data(tag), __index(__variant_npos) {}
655 template <size_t _Ip, class... _Args>
656 inline _LIBCPP_INLINE_VISIBILITY
657 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
659 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...),
662 inline _LIBCPP_INLINE_VISIBILITY
663 constexpr bool valueless_by_exception() const noexcept {
664 return index() == variant_npos;
667 inline _LIBCPP_INLINE_VISIBILITY
668 constexpr size_t index() const noexcept {
669 return __index == __variant_npos ? variant_npos : __index;
673 inline _LIBCPP_INLINE_VISIBILITY
674 constexpr auto&& __as_base() & { return *this; }
676 inline _LIBCPP_INLINE_VISIBILITY
677 constexpr auto&& __as_base() && { return _VSTD::move(*this); }
679 inline _LIBCPP_INLINE_VISIBILITY
680 constexpr auto&& __as_base() const & { return *this; }
682 inline _LIBCPP_INLINE_VISIBILITY
683 constexpr auto&& __as_base() const && { return _VSTD::move(*this); }
685 inline _LIBCPP_INLINE_VISIBILITY
686 static constexpr size_t __size() { return sizeof...(_Types); }
688 __union<_DestructibleTrait, 0, _Types...> __data;
689 unsigned int __index;
691 friend struct __access::__base;
692 friend struct __visitation::__base;
695 template <class _Traits, _Trait = _Traits::__destructible_trait>
696 class _LIBCPP_TEMPLATE_VIS __destructor;
698 #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \
699 template <class... _Types> \
700 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \
701 destructible_trait> \
702 : public __base<destructible_trait, _Types...> { \
703 using __base_type = __base<destructible_trait, _Types...>; \
706 using __base_type::__base_type; \
707 using __base_type::operator=; \
709 __destructor(const __destructor&) = default; \
710 __destructor(__destructor&&) = default; \
712 __destructor& operator=(const __destructor&) = default; \
713 __destructor& operator=(__destructor&&) = default; \
716 inline _LIBCPP_INLINE_VISIBILITY \
720 _LIBCPP_VARIANT_DESTRUCTOR(
721 _Trait::_TriviallyAvailable,
722 ~__destructor() = default;,
723 void __destroy() noexcept { this->__index = __variant_npos; });
725 _LIBCPP_VARIANT_DESTRUCTOR(
727 ~__destructor() { __destroy(); },
728 void __destroy() noexcept {
729 if (!this->valueless_by_exception()) {
730 __visitation::__base::__visit_alt(
731 [](auto& __alt) noexcept {
732 using __alt_type = decay_t<decltype(__alt)>;
737 this->__index = __variant_npos;
740 _LIBCPP_VARIANT_DESTRUCTOR(
741 _Trait::_Unavailable,
742 ~__destructor() = delete;,
743 void __destroy() noexcept = delete;);
745 #undef _LIBCPP_VARIANT_DESTRUCTOR
747 template <class _Traits>
748 class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> {
749 using __base_type = __destructor<_Traits>;
752 using __base_type::__base_type;
753 using __base_type::operator=;
756 template <size_t _Ip, class _Tp, class... _Args>
757 inline _LIBCPP_INLINE_VISIBILITY
758 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
759 ::new ((void*)_VSTD::addressof(__a))
760 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
764 template <class _Rhs>
765 inline _LIBCPP_INLINE_VISIBILITY
766 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) {
768 if (!__rhs.valueless_by_exception()) {
769 __visitation::__base::__visit_alt_at(
771 [](auto& __lhs_alt, auto&& __rhs_alt) {
774 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
776 __lhs, _VSTD::forward<_Rhs>(__rhs));
777 __lhs.__index = __rhs.index();
782 template <class _Traits, _Trait = _Traits::__move_constructible_trait>
783 class _LIBCPP_TEMPLATE_VIS __move_constructor;
785 #define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \
787 template <class... _Types> \
788 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \
789 move_constructible_trait> \
790 : public __constructor<__traits<_Types...>> { \
791 using __base_type = __constructor<__traits<_Types...>>; \
794 using __base_type::__base_type; \
795 using __base_type::operator=; \
797 __move_constructor(const __move_constructor&) = default; \
799 ~__move_constructor() = default; \
800 __move_constructor& operator=(const __move_constructor&) = default; \
801 __move_constructor& operator=(__move_constructor&&) = default; \
804 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
805 _Trait::_TriviallyAvailable,
806 __move_constructor(__move_constructor&& __that) = default;);
808 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
810 __move_constructor(__move_constructor&& __that) noexcept(
811 __all<is_nothrow_move_constructible_v<_Types>...>::value)
812 : __move_constructor(__valueless_t{}) {
813 this->__generic_construct(*this, _VSTD::move(__that));
816 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
817 _Trait::_Unavailable,
818 __move_constructor(__move_constructor&&) = delete;);
820 #undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
822 template <class _Traits, _Trait = _Traits::__copy_constructible_trait>
823 class _LIBCPP_TEMPLATE_VIS __copy_constructor;
825 #define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \
827 template <class... _Types> \
828 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \
829 copy_constructible_trait> \
830 : public __move_constructor<__traits<_Types...>> { \
831 using __base_type = __move_constructor<__traits<_Types...>>; \
834 using __base_type::__base_type; \
835 using __base_type::operator=; \
838 __copy_constructor(__copy_constructor&&) = default; \
839 ~__copy_constructor() = default; \
840 __copy_constructor& operator=(const __copy_constructor&) = default; \
841 __copy_constructor& operator=(__copy_constructor&&) = default; \
844 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
845 _Trait::_TriviallyAvailable,
846 __copy_constructor(const __copy_constructor& __that) = default;);
848 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
850 __copy_constructor(const __copy_constructor& __that)
851 : __copy_constructor(__valueless_t{}) {
852 this->__generic_construct(*this, __that);
855 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
856 _Trait::_Unavailable,
857 __copy_constructor(const __copy_constructor&) = delete;);
859 #undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
861 template <class _Traits>
862 class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
863 using __base_type = __copy_constructor<_Traits>;
866 using __base_type::__base_type;
867 using __base_type::operator=;
869 template <size_t _Ip, class... _Args>
870 inline _LIBCPP_INLINE_VISIBILITY
871 auto& __emplace(_Args&&... __args) {
873 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
874 _VSTD::forward<_Args>(__args)...);
880 template <bool _CopyAssign, size_t _Ip, class _Tp, class _Arg>
881 inline _LIBCPP_INLINE_VISIBILITY
882 void __assign_alt(__alt<_Ip, _Tp>& __a,
884 bool_constant<_CopyAssign> __tag) {
885 if (this->index() == _Ip) {
886 __a.__value = _VSTD::forward<_Arg>(__arg);
889 void operator()(true_type) const {
890 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
892 void operator()(false_type) const {
893 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
895 __assignment* __this;
897 } __impl{this, _VSTD::forward<_Arg>(__arg)};
902 template <class _That>
903 inline _LIBCPP_INLINE_VISIBILITY
904 void __generic_assign(_That&& __that) {
905 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
907 } else if (__that.valueless_by_exception()) {
910 __visitation::__base::__visit_alt_at(
912 [this](auto& __this_alt, auto&& __that_alt) {
915 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value,
916 is_lvalue_reference<_That>{});
918 *this, _VSTD::forward<_That>(__that));
923 template <class _Traits, _Trait = _Traits::__move_assignable_trait>
924 class _LIBCPP_TEMPLATE_VIS __move_assignment;
926 #define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \
928 template <class... _Types> \
929 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \
930 move_assignable_trait> \
931 : public __assignment<__traits<_Types...>> { \
932 using __base_type = __assignment<__traits<_Types...>>; \
935 using __base_type::__base_type; \
936 using __base_type::operator=; \
938 __move_assignment(const __move_assignment&) = default; \
939 __move_assignment(__move_assignment&&) = default; \
940 ~__move_assignment() = default; \
941 __move_assignment& operator=(const __move_assignment&) = default; \
945 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
946 _Trait::_TriviallyAvailable,
947 __move_assignment& operator=(__move_assignment&& __that) = default;);
949 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
951 __move_assignment& operator=(__move_assignment&& __that) noexcept(
952 __all<(is_nothrow_move_constructible_v<_Types> &&
953 is_nothrow_move_assignable_v<_Types>)...>::value) {
954 this->__generic_assign(_VSTD::move(__that));
958 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
959 _Trait::_Unavailable,
960 __move_assignment& operator=(__move_assignment&&) = delete;);
962 #undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
964 template <class _Traits, _Trait = _Traits::__copy_assignable_trait>
965 class _LIBCPP_TEMPLATE_VIS __copy_assignment;
967 #define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \
969 template <class... _Types> \
970 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \
971 copy_assignable_trait> \
972 : public __move_assignment<__traits<_Types...>> { \
973 using __base_type = __move_assignment<__traits<_Types...>>; \
976 using __base_type::__base_type; \
977 using __base_type::operator=; \
979 __copy_assignment(const __copy_assignment&) = default; \
980 __copy_assignment(__copy_assignment&&) = default; \
981 ~__copy_assignment() = default; \
983 __copy_assignment& operator=(__copy_assignment&&) = default; \
986 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
987 _Trait::_TriviallyAvailable,
988 __copy_assignment& operator=(const __copy_assignment& __that) = default;);
990 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
992 __copy_assignment& operator=(const __copy_assignment& __that) {
993 this->__generic_assign(__that);
997 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
998 _Trait::_Unavailable,
999 __copy_assignment& operator=(const __copy_assignment&) = delete;);
1001 #undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
1003 template <class... _Types>
1004 class _LIBCPP_TEMPLATE_VIS __impl
1005 : public __copy_assignment<__traits<_Types...>> {
1006 using __base_type = __copy_assignment<__traits<_Types...>>;
1009 using __base_type::__base_type;
1010 using __base_type::operator=;
1012 template <size_t _Ip, class _Arg>
1013 inline _LIBCPP_INLINE_VISIBILITY
1014 void __assign(_Arg&& __arg) {
1015 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
1016 _VSTD::forward<_Arg>(__arg),
1020 inline _LIBCPP_INLINE_VISIBILITY
1021 void __swap(__impl& __that) {
1022 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
1024 } else if (this->index() == __that.index()) {
1025 __visitation::__base::__visit_alt_at(
1027 [](auto& __this_alt, auto& __that_alt) {
1029 swap(__this_alt.__value, __that_alt.__value);
1034 __impl* __lhs = this;
1035 __impl* __rhs = _VSTD::addressof(__that);
1036 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
1037 _VSTD::swap(__lhs, __rhs);
1039 __impl __tmp(_VSTD::move(*__rhs));
1040 #ifndef _LIBCPP_NO_EXCEPTIONS
1041 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws
1042 // and `__tmp` is nothrow move constructible then we move `__tmp` back
1043 // into `__rhs` and provide the strong exception safety guarentee.
1045 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1047 if (__tmp.__move_nothrow()) {
1048 this->__generic_construct(*__rhs, _VSTD::move(__tmp));
1053 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1055 this->__generic_construct(*__lhs, _VSTD::move(__tmp));
1060 inline _LIBCPP_INLINE_VISIBILITY
1061 bool __move_nothrow() const {
1062 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
1063 return this->valueless_by_exception() || __results[this->index()];
1067 template <class... _Types>
1071 struct __overload<> { void operator()() const; };
1073 template <class _Tp, class... _Types>
1074 struct __overload<_Tp, _Types...> : __overload<_Types...> {
1075 using __overload<_Types...>::operator();
1076 __identity<_Tp> operator()(_Tp) const;
1079 template <class _Tp, class... _Types>
1080 using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type;
1082 } // __variant_detail
1084 template <class... _Types>
1085 class _LIBCPP_TEMPLATE_VIS variant
1086 : private __sfinae_ctor_base<
1087 __all<is_copy_constructible_v<_Types>...>::value,
1088 __all<is_move_constructible_v<_Types>...>::value>,
1089 private __sfinae_assign_base<
1090 __all<(is_copy_constructible_v<_Types> &&
1091 is_move_constructible_v<_Types> &&
1092 is_copy_assignable_v<_Types>)...>::value,
1093 __all<(is_move_constructible_v<_Types> &&
1094 is_move_assignable_v<_Types>)...>::value> {
1095 static_assert(0 < sizeof...(_Types),
1096 "variant must consist of at least one alternative.");
1098 static_assert(__all<!is_array_v<_Types>...>::value,
1099 "variant can not have an array type as an alternative.");
1101 static_assert(__all<!is_reference_v<_Types>...>::value,
1102 "variant can not have a reference type as an alternative.");
1104 static_assert(__all<!is_void_v<_Types>...>::value,
1105 "variant can not have a void type as an alternative.");
1107 using __first_type = variant_alternative_t<0, variant>;
1110 template <bool _Dummy = true,
1111 enable_if_t<__dependent_type<is_default_constructible<__first_type>,
1114 inline _LIBCPP_INLINE_VISIBILITY
1115 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
1116 : __impl(in_place_index<0>) {}
1118 variant(const variant&) = default;
1119 variant(variant&&) = default;
1123 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1124 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1126 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1127 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
1128 inline _LIBCPP_INLINE_VISIBILITY
1129 constexpr variant(_Arg&& __arg) noexcept(
1130 is_nothrow_constructible_v<_Tp, _Arg>)
1131 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {}
1133 template <size_t _Ip, class... _Args,
1134 class = enable_if_t<(_Ip < sizeof...(_Types)), int>,
1135 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1136 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1137 inline _LIBCPP_INLINE_VISIBILITY
1138 explicit constexpr variant(
1139 in_place_index_t<_Ip>,
1140 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
1141 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1147 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1148 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1149 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1151 inline _LIBCPP_INLINE_VISIBILITY
1152 explicit constexpr variant(
1153 in_place_index_t<_Ip>,
1154 initializer_list<_Up> __il,
1155 _Args&&... __args) noexcept(
1156 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
1157 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1163 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1164 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1165 inline _LIBCPP_INLINE_VISIBILITY
1166 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
1167 is_nothrow_constructible_v<_Tp, _Args...>)
1168 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1175 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1176 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1178 inline _LIBCPP_INLINE_VISIBILITY
1179 explicit constexpr variant(
1180 in_place_type_t<_Tp>,
1181 initializer_list<_Up> __il,
1182 _Args&&... __args) noexcept(
1183 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
1184 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1186 ~variant() = default;
1188 variant& operator=(const variant&) = default;
1189 variant& operator=(variant&&) = default;
1193 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1194 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1196 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1197 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>,
1199 inline _LIBCPP_INLINE_VISIBILITY
1200 variant& operator=(_Arg&& __arg) noexcept(
1201 is_nothrow_assignable_v<_Tp&, _Arg> &&
1202 is_nothrow_constructible_v<_Tp, _Arg>) {
1203 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg));
1210 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1211 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1212 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1213 inline _LIBCPP_INLINE_VISIBILITY
1214 _Tp& emplace(_Args&&... __args) {
1215 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1222 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1223 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1224 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1226 inline _LIBCPP_INLINE_VISIBILITY
1227 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
1228 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1235 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1236 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1237 inline _LIBCPP_INLINE_VISIBILITY
1238 _Tp& emplace(_Args&&... __args) {
1239 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1247 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1248 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1250 inline _LIBCPP_INLINE_VISIBILITY
1251 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
1252 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1255 inline _LIBCPP_INLINE_VISIBILITY
1256 constexpr bool valueless_by_exception() const noexcept {
1257 return __impl.valueless_by_exception();
1260 inline _LIBCPP_INLINE_VISIBILITY
1261 constexpr size_t index() const noexcept { return __impl.index(); }
1267 __dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
1268 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
1270 inline _LIBCPP_INLINE_VISIBILITY
1271 void swap(variant& __that) noexcept(
1272 __all<(is_nothrow_move_constructible_v<_Types> &&
1273 is_nothrow_swappable_v<_Types>)...>::value) {
1274 __impl.__swap(__that.__impl);
1278 __variant_detail::__impl<_Types...> __impl;
1280 friend struct __variant_detail::__access::__variant;
1281 friend struct __variant_detail::__visitation::__variant;
1284 template <size_t _Ip, class... _Types>
1285 inline _LIBCPP_INLINE_VISIBILITY
1286 constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
1287 return __v.index() == _Ip;
1290 template <class _Tp, class... _Types>
1291 inline _LIBCPP_INLINE_VISIBILITY
1292 constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
1293 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1296 template <size_t _Ip, class _Vp>
1297 inline _LIBCPP_INLINE_VISIBILITY
1298 static constexpr auto&& __generic_get(_Vp&& __v) {
1299 using __variant_detail::__access::__variant;
1300 if (!__holds_alternative<_Ip>(__v)) {
1301 __throw_bad_variant_access();
1303 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
1306 template <size_t _Ip, class... _Types>
1307 inline _LIBCPP_INLINE_VISIBILITY
1308 constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(
1309 variant<_Types...>& __v) {
1310 static_assert(_Ip < sizeof...(_Types));
1311 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1312 return __generic_get<_Ip>(__v);
1315 template <size_t _Ip, class... _Types>
1316 inline _LIBCPP_INLINE_VISIBILITY
1317 constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(
1318 variant<_Types...>&& __v) {
1319 static_assert(_Ip < sizeof...(_Types));
1320 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1321 return __generic_get<_Ip>(_VSTD::move(__v));
1324 template <size_t _Ip, class... _Types>
1325 inline _LIBCPP_INLINE_VISIBILITY
1326 constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(
1327 const variant<_Types...>& __v) {
1328 static_assert(_Ip < sizeof...(_Types));
1329 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1330 return __generic_get<_Ip>(__v);
1333 template <size_t _Ip, class... _Types>
1334 inline _LIBCPP_INLINE_VISIBILITY
1335 constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(
1336 const variant<_Types...>&& __v) {
1337 static_assert(_Ip < sizeof...(_Types));
1338 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1339 return __generic_get<_Ip>(_VSTD::move(__v));
1342 template <class _Tp, class... _Types>
1343 inline _LIBCPP_INLINE_VISIBILITY
1344 constexpr _Tp& get(variant<_Types...>& __v) {
1345 static_assert(!is_void_v<_Tp>);
1346 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
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>(
1357 template <class _Tp, class... _Types>
1358 inline _LIBCPP_INLINE_VISIBILITY
1359 constexpr const _Tp& get(const variant<_Types...>& __v) {
1360 static_assert(!is_void_v<_Tp>);
1361 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
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>(
1372 template <size_t _Ip, class _Vp>
1373 inline _LIBCPP_INLINE_VISIBILITY
1374 constexpr auto* __generic_get_if(_Vp* __v) noexcept {
1375 using __variant_detail::__access::__variant;
1376 return __v && __holds_alternative<_Ip>(*__v)
1377 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value)
1381 template <size_t _Ip, class... _Types>
1382 inline _LIBCPP_INLINE_VISIBILITY
1383 constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
1384 get_if(variant<_Types...>* __v) noexcept {
1385 static_assert(_Ip < sizeof...(_Types));
1386 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1387 return __generic_get_if<_Ip>(__v);
1390 template <size_t _Ip, class... _Types>
1391 inline _LIBCPP_INLINE_VISIBILITY
1392 constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
1393 get_if(const variant<_Types...>* __v) noexcept {
1394 static_assert(_Ip < sizeof...(_Types));
1395 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1396 return __generic_get_if<_Ip>(__v);
1399 template <class _Tp, class... _Types>
1400 inline _LIBCPP_INLINE_VISIBILITY
1401 constexpr add_pointer_t<_Tp>
1402 get_if(variant<_Types...>* __v) noexcept {
1403 static_assert(!is_void_v<_Tp>);
1404 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1407 template <class _Tp, class... _Types>
1408 inline _LIBCPP_INLINE_VISIBILITY
1409 constexpr add_pointer_t<const _Tp>
1410 get_if(const variant<_Types...>* __v) noexcept {
1411 static_assert(!is_void_v<_Tp>);
1412 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1415 template <class... _Types>
1416 inline _LIBCPP_INLINE_VISIBILITY
1417 constexpr bool operator==(const variant<_Types...>& __lhs,
1418 const variant<_Types...>& __rhs) {
1419 using __variant_detail::__visitation::__variant;
1420 if (__lhs.index() != __rhs.index()) return false;
1421 if (__lhs.valueless_by_exception()) return true;
1422 return __variant::__visit_value_at(__lhs.index(), equal_to<>{}, __lhs, __rhs);
1425 template <class... _Types>
1426 inline _LIBCPP_INLINE_VISIBILITY
1427 constexpr bool operator!=(const variant<_Types...>& __lhs,
1428 const variant<_Types...>& __rhs) {
1429 using __variant_detail::__visitation::__variant;
1430 if (__lhs.index() != __rhs.index()) return true;
1431 if (__lhs.valueless_by_exception()) return false;
1432 return __variant::__visit_value_at(
1433 __lhs.index(), not_equal_to<>{}, __lhs, __rhs);
1436 template <class... _Types>
1437 inline _LIBCPP_INLINE_VISIBILITY
1438 constexpr bool operator<(const variant<_Types...>& __lhs,
1439 const variant<_Types...>& __rhs) {
1440 using __variant_detail::__visitation::__variant;
1441 if (__rhs.valueless_by_exception()) return false;
1442 if (__lhs.valueless_by_exception()) return true;
1443 if (__lhs.index() < __rhs.index()) return true;
1444 if (__lhs.index() > __rhs.index()) return false;
1445 return __variant::__visit_value_at(__lhs.index(), less<>{}, __lhs, __rhs);
1448 template <class... _Types>
1449 inline _LIBCPP_INLINE_VISIBILITY
1450 constexpr bool operator>(const variant<_Types...>& __lhs,
1451 const variant<_Types...>& __rhs) {
1452 using __variant_detail::__visitation::__variant;
1453 if (__lhs.valueless_by_exception()) return false;
1454 if (__rhs.valueless_by_exception()) return true;
1455 if (__lhs.index() > __rhs.index()) return true;
1456 if (__lhs.index() < __rhs.index()) return false;
1457 return __variant::__visit_value_at(__lhs.index(), greater<>{}, __lhs, __rhs);
1460 template <class... _Types>
1461 inline _LIBCPP_INLINE_VISIBILITY
1462 constexpr bool operator<=(const variant<_Types...>& __lhs,
1463 const variant<_Types...>& __rhs) {
1464 using __variant_detail::__visitation::__variant;
1465 if (__lhs.valueless_by_exception()) return true;
1466 if (__rhs.valueless_by_exception()) return false;
1467 if (__lhs.index() < __rhs.index()) return true;
1468 if (__lhs.index() > __rhs.index()) return false;
1469 return __variant::__visit_value_at(
1470 __lhs.index(), less_equal<>{}, __lhs, __rhs);
1473 template <class... _Types>
1474 inline _LIBCPP_INLINE_VISIBILITY
1475 constexpr bool operator>=(const variant<_Types...>& __lhs,
1476 const variant<_Types...>& __rhs) {
1477 using __variant_detail::__visitation::__variant;
1478 if (__rhs.valueless_by_exception()) return true;
1479 if (__lhs.valueless_by_exception()) return false;
1480 if (__lhs.index() > __rhs.index()) return true;
1481 if (__lhs.index() < __rhs.index()) return false;
1482 return __variant::__visit_value_at(
1483 __lhs.index(), greater_equal<>{}, __lhs, __rhs);
1486 template <class _Visitor, class... _Vs>
1487 inline _LIBCPP_INLINE_VISIBILITY
1488 constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
1489 using __variant_detail::__visitation::__variant;
1490 bool __results[] = {__vs.valueless_by_exception()...};
1491 for (bool __result : __results) {
1493 __throw_bad_variant_access();
1496 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
1497 _VSTD::forward<_Vs>(__vs)...);
1500 struct _LIBCPP_TEMPLATE_VIS monostate {};
1502 inline _LIBCPP_INLINE_VISIBILITY
1503 constexpr bool operator<(monostate, monostate) noexcept { return false; }
1505 inline _LIBCPP_INLINE_VISIBILITY
1506 constexpr bool operator>(monostate, monostate) noexcept { return false; }
1508 inline _LIBCPP_INLINE_VISIBILITY
1509 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
1511 inline _LIBCPP_INLINE_VISIBILITY
1512 constexpr bool operator>=(monostate, monostate) noexcept { return true; }
1514 inline _LIBCPP_INLINE_VISIBILITY
1515 constexpr bool operator==(monostate, monostate) noexcept { return true; }
1517 inline _LIBCPP_INLINE_VISIBILITY
1518 constexpr bool operator!=(monostate, monostate) noexcept { return false; }
1520 template <class... _Types>
1521 inline _LIBCPP_INLINE_VISIBILITY
1522 auto swap(variant<_Types...>& __lhs,
1523 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs)))
1524 -> decltype(__lhs.swap(__rhs)) {
1528 template <class... _Types>
1529 struct _LIBCPP_TEMPLATE_VIS hash<
1530 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> {
1531 using argument_type = variant<_Types...>;
1532 using result_type = size_t;
1534 inline _LIBCPP_INLINE_VISIBILITY
1535 result_type operator()(const argument_type& __v) const {
1536 using __variant_detail::__visitation::__variant;
1538 __v.valueless_by_exception()
1539 ? 299792458 // Random value chosen by the universe upon creation
1540 : __variant::__visit_alt(
1541 [](const auto& __alt) {
1542 using __alt_type = decay_t<decltype(__alt)>;
1543 using __value_type = remove_const_t<
1544 typename __alt_type::__value_type>;
1545 return hash<__value_type>{}(__alt.__value);
1548 return __hash_combine(__res, hash<size_t>{}(__v.index()));
1553 struct _LIBCPP_TEMPLATE_VIS hash<monostate> {
1554 using argument_type = monostate;
1555 using result_type = size_t;
1557 inline _LIBCPP_INLINE_VISIBILITY
1558 result_type operator()(const argument_type&) const _NOEXCEPT {
1559 return 66740831; // return a fundamentally attractive random value.
1563 #endif // _LIBCPP_STD_VER > 14
1565 _LIBCPP_END_NAMESPACE_STD
1567 #endif // _LIBCPP_VARIANT