29 #ifndef _GLIBCXX_VARIANT
30 #define _GLIBCXX_VARIANT 1
32 #pragma GCC system_header
34 #if __cplusplus >= 201703L
36 #include <type_traits>
48 #if __cplusplus > 201703L
52 namespace std _GLIBCXX_VISIBILITY(default)
54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
60 template<
size_t _Np,
typename... _Types>
63 template<
size_t _Np,
typename _First,
typename... _Rest>
64 struct _Nth_type<_Np, _First, _Rest...>
65 : _Nth_type<_Np-1, _Rest...> { };
67 template<
typename _First,
typename... _Rest>
68 struct _Nth_type<0, _First, _Rest...>
69 {
using type = _First; };
74 #define __cpp_lib_variant 201606L
76 template<
typename... _Types>
class tuple;
77 template<
typename... _Types>
class variant;
78 template <
typename>
struct hash;
80 template<
typename _Variant>
83 template<
typename _Variant>
84 struct variant_size<const _Variant> : variant_size<_Variant> {};
86 template<
typename _Variant>
87 struct variant_size<volatile _Variant> : variant_size<_Variant> {};
89 template<
typename _Variant>
90 struct variant_size<const volatile _Variant> : variant_size<_Variant> {};
92 template<
typename... _Types>
93 struct variant_size<variant<_Types...>>
96 template<
typename _Variant>
97 inline constexpr
size_t variant_size_v = variant_size<_Variant>::value;
99 template<
size_t _Np,
typename _Variant>
100 struct variant_alternative;
102 template<
size_t _Np,
typename _First,
typename... _Rest>
103 struct variant_alternative<_Np, variant<_First, _Rest...>>
104 : variant_alternative<_Np-1, variant<_Rest...>> {};
106 template<
typename _First,
typename... _Rest>
107 struct variant_alternative<0, variant<_First, _Rest...>>
108 {
using type = _First; };
110 template<
size_t _Np,
typename _Variant>
111 using variant_alternative_t =
112 typename variant_alternative<_Np, _Variant>::type;
114 template<
size_t _Np,
typename _Variant>
115 struct variant_alternative<_Np, const _Variant>
116 {
using type = add_const_t<variant_alternative_t<_Np, _Variant>>; };
118 template<
size_t _Np,
typename _Variant>
119 struct variant_alternative<_Np, volatile _Variant>
120 {
using type = add_volatile_t<variant_alternative_t<_Np, _Variant>>; };
122 template<
size_t _Np,
typename _Variant>
123 struct variant_alternative<_Np, const volatile _Variant>
124 {
using type = add_cv_t<variant_alternative_t<_Np, _Variant>>; };
126 inline constexpr
size_t variant_npos = -1;
128 template<
size_t _Np,
typename... _Types>
129 constexpr variant_alternative_t<_Np, variant<_Types...>>&
130 get(variant<_Types...>&);
132 template<
size_t _Np,
typename... _Types>
133 constexpr variant_alternative_t<_Np, variant<_Types...>>&&
134 get(variant<_Types...>&&);
136 template<
size_t _Np,
typename... _Types>
137 constexpr variant_alternative_t<_Np, variant<_Types...>>
const&
138 get(
const variant<_Types...>&);
140 template<
size_t _Np,
typename... _Types>
141 constexpr variant_alternative_t<_Np, variant<_Types...>>
const&&
142 get(
const variant<_Types...>&&);
144 template<
typename _Result_type,
typename _Visitor,
typename... _Variants>
145 constexpr decltype(
auto)
146 __do_visit(_Visitor&& __visitor, _Variants&&... __variants);
148 template <typename... _Types, typename _Tp>
150 __variant_cast(_Tp&& __rhs)
152 if constexpr (is_lvalue_reference_v<_Tp>)
154 if constexpr (is_const_v<remove_reference_t<_Tp>>)
155 return static_cast<const variant<_Types...>&>(__rhs);
157 return static_cast<variant<_Types...>&>(__rhs);
160 return static_cast<variant<_Types...>&&>(__rhs);
169 template<
typename _Tp,
typename... _Types>
172 template<
typename _Tp,
typename... _Types>
173 inline constexpr
size_t __index_of_v = __index_of<_Tp, _Types...>::value;
175 template<
typename _Tp,
typename _First,
typename... _Rest>
176 struct __index_of<_Tp, _First, _Rest...> :
178 ? 0 : __index_of_v<_Tp, _Rest...> + 1> {};
181 struct __variant_cookie {};
183 struct __variant_idx_cookie {
using type = __variant_idx_cookie; };
185 template<
typename>
struct __deduce_visit_result { };
188 template<
typename _Visitor,
typename... _Variants>
190 __raw_visit(_Visitor&& __visitor, _Variants&&... __variants)
192 std::__do_visit<__variant_cookie>(std::forward<_Visitor>(__visitor),
193 std::forward<_Variants>(__variants)...);
197 template<
typename _Visitor,
typename... _Variants>
199 __raw_idx_visit(_Visitor&& __visitor, _Variants&&... __variants)
201 std::__do_visit<__variant_idx_cookie>(std::forward<_Visitor>(__visitor),
202 std::forward<_Variants>(__variants)...);
207 template<
typename _Type,
bool = std::is_trivially_destructible_v<_Type>>
208 struct _Uninitialized;
210 template<
typename _Type>
211 struct _Uninitialized<_Type, true>
213 template<
typename... _Args>
215 _Uninitialized(in_place_index_t<0>, _Args&&... __args)
216 : _M_storage(std::
forward<_Args>(__args)...)
219 constexpr
const _Type& _M_get() const & noexcept
220 {
return _M_storage; }
222 constexpr _Type& _M_get() & noexcept
223 {
return _M_storage; }
225 constexpr
const _Type&& _M_get() const && noexcept
228 constexpr _Type&& _M_get() && noexcept
234 template<
typename _Type>
235 struct _Uninitialized<_Type, false>
237 template<
typename... _Args>
239 _Uninitialized(in_place_index_t<0>, _Args&&... __args)
242 _Type(std::
forward<_Args>(__args)...);
245 const _Type& _M_get() const & noexcept
246 {
return *_M_storage._M_ptr(); }
248 _Type& _M_get() & noexcept
249 {
return *_M_storage._M_ptr(); }
251 const _Type&& _M_get() const && noexcept
252 {
return std::move(*_M_storage._M_ptr()); }
254 _Type&& _M_get() && noexcept
255 {
return std::move(*_M_storage._M_ptr()); }
257 __gnu_cxx::__aligned_membuf<_Type> _M_storage;
260 template<
typename _Union>
261 constexpr decltype(
auto)
262 __get(in_place_index_t<0>, _Union&& __u) noexcept
263 {
return std::forward<_Union>(__u)._M_first._M_get(); }
265 template<
size_t _Np,
typename _Union>
266 constexpr decltype(
auto)
267 __get(in_place_index_t<_Np>, _Union&& __u) noexcept
269 return __variant::__get(in_place_index<_Np-1>,
270 std::forward<_Union>(__u)._M_rest);
274 template<
size_t _Np,
typename _Variant>
275 constexpr decltype(
auto)
276 __get(_Variant&& __v) noexcept
278 return __variant::__get(std::in_place_index<_Np>,
279 std::forward<_Variant>(__v)._M_u);
282 template<
typename... _Types>
285 static constexpr
bool _S_default_ctor =
286 is_default_constructible_v<
typename _Nth_type<0, _Types...>::type>;
287 static constexpr
bool _S_copy_ctor =
288 (is_copy_constructible_v<_Types> && ...);
289 static constexpr
bool _S_move_ctor =
290 (is_move_constructible_v<_Types> && ...);
291 static constexpr
bool _S_copy_assign =
293 && (is_copy_assignable_v<_Types> && ...);
294 static constexpr
bool _S_move_assign =
296 && (is_move_assignable_v<_Types> && ...);
298 static constexpr
bool _S_trivial_dtor =
299 (is_trivially_destructible_v<_Types> && ...);
300 static constexpr
bool _S_trivial_copy_ctor =
301 (is_trivially_copy_constructible_v<_Types> && ...);
302 static constexpr
bool _S_trivial_move_ctor =
303 (is_trivially_move_constructible_v<_Types> && ...);
304 static constexpr
bool _S_trivial_copy_assign =
305 _S_trivial_dtor && _S_trivial_copy_ctor
306 && (is_trivially_copy_assignable_v<_Types> && ...);
307 static constexpr
bool _S_trivial_move_assign =
308 _S_trivial_dtor && _S_trivial_move_ctor
309 && (is_trivially_move_assignable_v<_Types> && ...);
313 static constexpr
bool _S_nothrow_default_ctor =
314 is_nothrow_default_constructible_v<
315 typename _Nth_type<0, _Types...>::type>;
316 static constexpr
bool _S_nothrow_copy_ctor =
false;
317 static constexpr
bool _S_nothrow_move_ctor =
318 (is_nothrow_move_constructible_v<_Types> && ...);
319 static constexpr
bool _S_nothrow_copy_assign =
false;
320 static constexpr
bool _S_nothrow_move_assign =
322 && (is_nothrow_move_assignable_v<_Types> && ...);
326 template<
typename... _Types>
327 union _Variadic_union { };
329 template<
typename _First,
typename... _Rest>
330 union _Variadic_union<_First, _Rest...>
332 constexpr _Variadic_union() : _M_rest() { }
334 template<
typename... _Args>
335 constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args)
336 : _M_first(in_place_index<0>, std::
forward<_Args>(__args)...)
339 template<
size_t _Np,
typename... _Args>
340 constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args)
341 : _M_rest(in_place_index<_Np-1>, std::
forward<_Args>(__args)...)
344 _Uninitialized<_First> _M_first;
345 _Variadic_union<_Rest...> _M_rest;
353 template<
typename _Tp>
354 struct _Never_valueless_alt
355 : __and_<bool_constant<sizeof(_Tp) <= 256>, is_trivially_copyable<_Tp>>
368 template <typename... _Types>
369 constexpr bool __never_valueless()
371 return _Traits<_Types...>::_S_move_assign
372 && (_Never_valueless_alt<_Types>::value && ...);
376 template<bool __trivially_destructible, typename... _Types>
377 struct _Variant_storage;
379 template <typename... _Types>
380 using __select_index =
381 typename __select_int::_Select_int_base<sizeof...(_Types),
383 unsigned short>::type::value_type;
385 template<typename... _Types>
386 struct _Variant_storage<false, _Types...>
390 : _M_index(static_cast<__index_type>(variant_npos))
393 template<size_t _Np, typename... _Args>
395 _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
396 : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...),
402 if (!_M_valid()) [[unlikely]]
405 std::__do_visit<void>([](auto&& __this_mem) mutable
407 std::_Destroy(std::__addressof(__this_mem));
408 }, __variant_cast<_Types...>(*this));
410 _M_index = static_cast<__index_type>(variant_npos);
417 _M_storage() const noexcept
419 return const_cast<void*>(static_cast<const void*>(
420 std::addressof(_M_u)));
424 _M_valid() const noexcept
426 if constexpr (__variant::__never_valueless<_Types...>())
428 return this->_M_index != __index_type(variant_npos);
431 _Variadic_union<_Types...> _M_u;
432 using __index_type = __select_index<_Types...>;
433 __index_type _M_index;
436 template<typename... _Types>
437 struct _Variant_storage<true, _Types...>
441 : _M_index(static_cast<__index_type>(variant_npos))
444 template<
size_t _Np,
typename... _Args>
446 _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
447 : _M_u(in_place_index<_Np>, std::
forward<_Args>(__args)...),
451 void _M_reset() noexcept
452 { _M_index =
static_cast<__index_type
>(variant_npos); }
455 _M_storage() const noexcept
457 return const_cast<void*
>(
static_cast<const void*
>(
462 _M_valid() const noexcept
464 if constexpr (__variant::__never_valueless<_Types...>())
466 return this->_M_index != static_cast<__index_type>(variant_npos);
469 _Variadic_union<_Types...> _M_u;
470 using __index_type = __select_index<_Types...>;
471 __index_type _M_index;
474 template<typename... _Types>
475 using _Variant_storage_alias =
476 _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>;
478 template<typename _Tp, typename _Up>
479 void __variant_construct_single(_Tp&& __lhs, _Up&& __rhs_mem)
482 using _Type = remove_reference_t<decltype(__rhs_mem)>;
483 if constexpr (!is_same_v<_Type, __variant_cookie>)
485 _Type(std::
forward<decltype(__rhs_mem)>(__rhs_mem));
488 template<
typename... _Types,
typename _Tp,
typename _Up>
489 void __variant_construct(_Tp&& __lhs, _Up&& __rhs)
491 __lhs._M_index = __rhs._M_index;
492 __variant::__raw_visit([&__lhs](
auto&& __rhs_mem)
mutable
494 __variant_construct_single(std::forward<_Tp>(__lhs),
496 }, __variant_cast<_Types...>(std::forward<_Up>(__rhs)));
502 template<bool,
typename... _Types>
503 struct _Copy_ctor_base : _Variant_storage_alias<_Types...>
505 using _Base = _Variant_storage_alias<_Types...>;
508 _Copy_ctor_base(
const _Copy_ctor_base& __rhs)
509 noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor)
511 __variant_construct<_Types...>(*
this, __rhs);
514 _Copy_ctor_base(_Copy_ctor_base&&) =
default;
515 _Copy_ctor_base& operator=(
const _Copy_ctor_base&) =
default;
516 _Copy_ctor_base& operator=(_Copy_ctor_base&&) =
default;
519 template<
typename... _Types>
520 struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...>
522 using _Base = _Variant_storage_alias<_Types...>;
526 template<
typename... _Types>
527 using _Copy_ctor_alias =
528 _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>;
530 template<bool,
typename... _Types>
531 struct _Move_ctor_base : _Copy_ctor_alias<_Types...>
533 using _Base = _Copy_ctor_alias<_Types...>;
536 _Move_ctor_base(_Move_ctor_base&& __rhs)
537 noexcept(_Traits<_Types...>::_S_nothrow_move_ctor)
539 __variant_construct<_Types...>(*
this,
std::move(__rhs));
542 template<
typename _Up>
543 void _M_destructive_move(
unsigned short __rhs_index, _Up&& __rhs)
546 __variant_construct_single(*
this, std::forward<_Up>(__rhs));
547 this->_M_index = __rhs_index;
550 template<
typename _Up>
551 void _M_destructive_copy(
unsigned short __rhs_index,
const _Up& __rhs)
554 __variant_construct_single(*
this, __rhs);
555 this->_M_index = __rhs_index;
558 _Move_ctor_base(
const _Move_ctor_base&) =
default;
559 _Move_ctor_base& operator=(
const _Move_ctor_base&) =
default;
560 _Move_ctor_base& operator=(_Move_ctor_base&&) =
default;
563 template<
typename... _Types>
564 struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...>
566 using _Base = _Copy_ctor_alias<_Types...>;
569 template<
typename _Up>
570 void _M_destructive_move(
unsigned short __rhs_index, _Up&& __rhs)
573 __variant_construct_single(*
this, std::forward<_Up>(__rhs));
574 this->_M_index = __rhs_index;
577 template<
typename _Up>
578 void _M_destructive_copy(
unsigned short __rhs_index,
const _Up& __rhs)
581 __variant_construct_single(*
this, __rhs);
582 this->_M_index = __rhs_index;
586 template<
typename... _Types>
587 using _Move_ctor_alias =
588 _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>;
590 template<bool,
typename... _Types>
591 struct _Copy_assign_base : _Move_ctor_alias<_Types...>
593 using _Base = _Move_ctor_alias<_Types...>;
597 operator=(
const _Copy_assign_base& __rhs)
598 noexcept(_Traits<_Types...>::_S_nothrow_copy_assign)
600 __variant::__raw_idx_visit(
601 [
this](
auto&& __rhs_mem,
auto __rhs_index)
mutable
603 if constexpr (__rhs_index != variant_npos)
605 if (this->_M_index == __rhs_index)
606 __variant::__get<__rhs_index>(*this) = __rhs_mem;
609 using __rhs_type = __remove_cvref_t<decltype(__rhs_mem)>;
610 if constexpr (is_nothrow_copy_constructible_v<__rhs_type>
611 || !is_nothrow_move_constructible_v<__rhs_type>)
619 this->_M_destructive_copy(__rhs_index, __rhs_mem);
621 __variant_cast<_Types...>(*this)
622 = variant<_Types...>(std::in_place_index<__rhs_index>,
628 }, __variant_cast<_Types...>(__rhs));
632 _Copy_assign_base(const _Copy_assign_base&) = default;
633 _Copy_assign_base(_Copy_assign_base&&) = default;
634 _Copy_assign_base& operator=(_Copy_assign_base&&) = default;
637 template<typename... _Types>
638 struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...>
640 using _Base = _Move_ctor_alias<_Types...>;
644 template<
typename... _Types>
645 using _Copy_assign_alias =
646 _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, _Types...>;
648 template<bool,
typename... _Types>
649 struct _Move_assign_base : _Copy_assign_alias<_Types...>
651 using _Base = _Copy_assign_alias<_Types...>;
655 operator=(_Move_assign_base&& __rhs)
656 noexcept(_Traits<_Types...>::_S_nothrow_move_assign)
658 __variant::__raw_idx_visit(
659 [
this](
auto&& __rhs_mem,
auto __rhs_index)
mutable
661 if constexpr (__rhs_index != variant_npos)
663 if (this->_M_index == __rhs_index)
664 __variant::__get<__rhs_index>(*this) =
std::move(__rhs_mem);
666 __variant_cast<_Types...>(*this)
667 .template emplace<__rhs_index>(
std::move(__rhs_mem));
671 }, __variant_cast<_Types...>(__rhs));
675 _Move_assign_base(
const _Move_assign_base&) =
default;
676 _Move_assign_base(_Move_assign_base&&) =
default;
677 _Move_assign_base& operator=(
const _Move_assign_base&) =
default;
680 template<
typename... _Types>
681 struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...>
683 using _Base = _Copy_assign_alias<_Types...>;
687 template<
typename... _Types>
688 using _Move_assign_alias =
689 _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, _Types...>;
691 template<
typename... _Types>
692 struct _Variant_base : _Move_assign_alias<_Types...>
694 using _Base = _Move_assign_alias<_Types...>;
698 noexcept(_Traits<_Types...>::_S_nothrow_default_ctor)
699 : _Variant_base(in_place_index<0>) { }
701 template<
size_t _Np,
typename... _Args>
703 _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args)
704 : _Base(__i, std::
forward<_Args>(__args)...)
707 _Variant_base(
const _Variant_base&) =
default;
708 _Variant_base(_Variant_base&&) =
default;
709 _Variant_base& operator=(
const _Variant_base&) =
default;
710 _Variant_base& operator=(_Variant_base&&) =
default;
714 template<
typename _Tp,
typename _Tuple>
715 struct __tuple_count;
717 template<
typename _Tp,
typename _Tuple>
718 inline constexpr
size_t __tuple_count_v =
719 __tuple_count<_Tp, _Tuple>::value;
721 template<
typename _Tp,
typename... _Types>
722 struct __tuple_count<_Tp, tuple<_Types...>>
723 : integral_constant<size_t, 0> { };
725 template<
typename _Tp,
typename _First,
typename... _Rest>
726 struct __tuple_count<_Tp, tuple<_First, _Rest...>>
729 __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { };
732 template<
typename _Tp,
typename... _Types>
733 inline constexpr
bool __exactly_once =
734 __tuple_count_v<_Tp, tuple<_Types...>> == 1;
737 template<
typename _Ti>
struct _Arr { _Ti _M_x[1]; };
740 template<
size_t _Ind,
typename _Tp,
typename _Ti,
741 bool _Ti_is_cv_bool = is_same_v<remove_cv_t<_Ti>,
bool>,
751 template<
size_t _Ind,
typename _Tp,
typename _Ti>
752 struct _Build_FUN<_Ind, _Tp, _Ti, false,
753 void_t<decltype(_Arr<_Ti>{{std::declval<_Tp>()}})>>
756 static integral_constant<size_t, _Ind> _S_fun(_Ti);
760 template<
size_t _Ind,
typename _Tp,
typename _Ti>
761 struct _Build_FUN<_Ind, _Tp, _Ti, true,
762 enable_if_t<is_same_v<__remove_cvref_t<_Tp>, bool>>>
765 static integral_constant<size_t, _Ind> _S_fun(_Ti);
768 template<
typename _Tp,
typename _Variant,
769 typename = make_index_sequence<variant_size_v<_Variant>>>
772 template<
typename _Tp,
typename... _Ti,
size_t... _Ind>
774 : _Build_FUN<_Ind, _Tp, _Ti>...
776 using _Build_FUN<_Ind, _Tp, _Ti>::_S_fun...;
781 template<
typename _Tp,
typename _Variant>
783 = decltype(_Build_FUNs<_Tp, _Variant>::_S_fun(std::declval<_Tp>()));
786 template<
typename _Tp,
typename _Variant,
typename =
void>
787 struct __accepted_index
788 : integral_constant<size_t, variant_npos>
791 template<
typename _Tp,
typename _Variant>
792 struct __accepted_index<_Tp, _Variant,
void_t<_FUN_type<_Tp, _Variant>>>
793 : _FUN_type<_Tp, _Variant>
797 template<
typename _Variant>
798 void* __get_storage(_Variant&& __v) noexcept
799 {
return __v._M_storage(); }
801 template <
typename _Maybe_variant_cookie,
typename _Variant>
802 struct _Extra_visit_slot_needed
804 template <
typename>
struct _Variant_never_valueless;
806 template <
typename... _Types>
807 struct _Variant_never_valueless<variant<_Types...>>
808 : bool_constant<__variant::__never_valueless<_Types...>()> {};
810 static constexpr
bool value =
811 (is_same_v<_Maybe_variant_cookie, __variant_cookie>
812 || is_same_v<_Maybe_variant_cookie, __variant_idx_cookie>)
813 && !_Variant_never_valueless<__remove_cvref_t<_Variant>>::value;
817 template<
typename _Tp,
size_t... _Dimensions>
821 template<
typename _Tp>
822 struct _Multi_array<_Tp>
825 struct __untag_result
827 {
using element_type = _Tp; };
829 template <
typename... _Args>
830 struct __untag_result<const void(*)(_Args...)>
832 {
using element_type = void(*)(_Args...); };
834 template <
typename... _Args>
835 struct __untag_result<__variant_cookie(*)(_Args...)>
837 {
using element_type = void(*)(_Args...); };
839 template <
typename... _Args>
840 struct __untag_result<__variant_idx_cookie(*)(_Args...)>
842 {
using element_type = void(*)(_Args...); };
844 template <
typename _Res,
typename... _Args>
845 struct __untag_result<__deduce_visit_result<_Res>(*)(_Args...)>
847 {
using element_type = _Res(*)(_Args...); };
849 using __result_is_deduced = __untag_result<_Tp>;
851 constexpr
const typename __untag_result<_Tp>::element_type&
855 typename __untag_result<_Tp>::element_type _M_data;
859 template<
typename _Ret,
861 typename... _Variants,
862 size_t __first,
size_t... __rest>
863 struct _Multi_array<_Ret(*)(_Visitor, _Variants...), __first, __rest...>
865 static constexpr
size_t __index =
866 sizeof...(_Variants) -
sizeof...(__rest) - 1;
868 using _Variant =
typename _Nth_type<__index, _Variants...>::type;
870 static constexpr
int __do_cookie =
871 _Extra_visit_slot_needed<_Ret, _Variant>::value ? 1 : 0;
873 using _Tp = _Ret(*)(_Visitor, _Variants...);
875 template<
typename... _Args>
876 constexpr decltype(
auto)
877 _M_access(
size_t __first_index, _Args... __rest_indices)
const
879 return _M_arr[__first_index + __do_cookie]
880 ._M_access(__rest_indices...);
883 _Multi_array<_Tp, __rest...> _M_arr[__first + __do_cookie];
913 template<
typename _Array_type,
typename _Index_seq>
914 struct __gen_vtable_impl;
923 template<
typename _Result_type,
typename _Visitor,
size_t... __dimensions,
924 typename... _Variants,
size_t... __indices>
925 struct __gen_vtable_impl<
926 _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>,
931 _Variants...>::type>;
933 _Multi_array<_Result_type (*)(_Visitor, _Variants...),
936 static constexpr _Array_type
939 _Array_type __vtable{};
945 template<
size_t... __var_indices>
946 static constexpr
void
947 _S_apply_all_alts(_Array_type& __vtable,
950 if constexpr (_Extra_visit_slot_needed<_Result_type, _Next>::value)
951 (_S_apply_single_alt<true, __var_indices>(
952 __vtable._M_arr[__var_indices + 1],
953 &(__vtable._M_arr[0])), ...);
955 (_S_apply_single_alt<false, __var_indices>(
956 __vtable._M_arr[__var_indices]), ...);
959 template<
bool __do_cookie,
size_t __index,
typename _Tp>
960 static constexpr
void
961 _S_apply_single_alt(_Tp& __element, _Tp* __cookie_element =
nullptr)
963 if constexpr (__do_cookie)
965 __element = __gen_vtable_impl<
968 *__cookie_element = __gen_vtable_impl<
974 __element = __gen_vtable_impl<
975 remove_reference_t<decltype(__element)>,
984 template<
typename _Result_type,
typename _Visitor,
typename... _Variants,
986 struct __gen_vtable_impl<
987 _Multi_array<_Result_type (*)(_Visitor, _Variants...)>,
991 _Multi_array<_Result_type (*)(_Visitor, _Variants...)>;
993 template<
size_t __index,
typename _Variant>
994 static constexpr decltype(
auto)
995 __element_by_index_or_cookie(_Variant&& __var) noexcept
997 if constexpr (__index != variant_npos)
998 return __variant::__get<__index>(std::
forward<_Variant>(__var));
1000 return __variant_cookie{};
1003 static constexpr decltype(
auto)
1004 __visit_invoke(_Visitor&& __visitor, _Variants... __vars)
1006 if constexpr (is_same_v<_Result_type, __variant_idx_cookie>)
1009 std::__invoke(std::
forward<_Visitor>(__visitor),
1010 __element_by_index_or_cookie<__indices>(
1011 std::
forward<_Variants>(__vars))...,
1012 integral_constant<
size_t, __indices>()...);
1013 else if constexpr (is_same_v<_Result_type, __variant_cookie>)
1015 std::__invoke(std::
forward<_Visitor>(__visitor),
1016 __element_by_index_or_cookie<__indices>(
1017 std::
forward<_Variants>(__vars))...);
1018 else if constexpr (_Array_type::__result_is_deduced::value)
1020 return std::__invoke(std::
forward<_Visitor>(__visitor),
1021 __element_by_index_or_cookie<__indices>(
1022 std::
forward<_Variants>(__vars))...);
1024 return std::__invoke_r<_Result_type>(
1025 std::
forward<_Visitor>(__visitor),
1026 __variant::__get<__indices>(std::
forward<_Variants>(__vars))...);
1029 static constexpr auto
1031 {
return _Array_type{&__visit_invoke}; }
1034 template<
typename _Result_type,
typename _Visitor,
typename... _Variants>
1038 _Multi_array<_Result_type (*)(_Visitor, _Variants...),
1039 variant_size_v<remove_reference_t<_Variants>>...>;
1041 static constexpr _Array_type _S_vtable
1042 = __gen_vtable_impl<_Array_type, std::index_sequence<>>::_S_apply();
1045 template<
size_t _Np,
typename _Tp>
1046 struct _Base_dedup :
public _Tp { };
1048 template<
typename _Variant,
typename __indices>
1049 struct _Variant_hash_base;
1051 template<
typename... _Types,
size_t... __indices>
1052 struct _Variant_hash_base<variant<_Types...>,
1054 : _Base_dedup<__indices, __poison_hash<remove_const_t<_Types>>>... { };
1059 template<
size_t _Np,
typename _Variant,
typename... _Args>
1060 void __variant_construct_by_index(_Variant& __v, _Args&&... __args)
1063 auto&& __storage = __detail::__variant::__get<_Np>(__v);
1066 (std::
forward<_Args>(__args)...);
1069 template<typename _Tp, typename... _Types>
1071 holds_alternative(const variant<_Types...>& __v) noexcept
1073 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1074 "T must occur exactly once in alternatives");
1075 return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>;
1078 template<
typename _Tp,
typename... _Types>
1079 constexpr _Tp&
get(variant<_Types...>& __v)
1081 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1082 "T must occur exactly once in alternatives");
1083 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1084 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
1087 template<
typename _Tp,
typename... _Types>
1088 constexpr _Tp&&
get(variant<_Types...>&& __v)
1090 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1091 "T must occur exactly once in alternatives");
1092 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1093 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
1097 template<
typename _Tp,
typename... _Types>
1098 constexpr
const _Tp&
get(
const variant<_Types...>& __v)
1100 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1101 "T must occur exactly once in alternatives");
1102 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1103 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
1106 template<
typename _Tp,
typename... _Types>
1107 constexpr
const _Tp&&
get(
const variant<_Types...>&& __v)
1109 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1110 "T must occur exactly once in alternatives");
1111 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1112 return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
1116 template<
size_t _Np,
typename... _Types>
1117 constexpr
add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>>
1118 get_if(variant<_Types...>* __ptr) noexcept
1120 using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
1121 static_assert(_Np <
sizeof...(_Types),
1122 "The index must be in [0, number of alternatives)");
1123 static_assert(!is_void_v<_Alternative_type>,
"_Tp must not be void");
1124 if (__ptr && __ptr->index() == _Np)
1129 template<
size_t _Np,
typename... _Types>
1131 add_pointer_t<
const variant_alternative_t<_Np, variant<_Types...>>>
1132 get_if(
const variant<_Types...>* __ptr) noexcept
1134 using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
1135 static_assert(_Np <
sizeof...(_Types),
1136 "The index must be in [0, number of alternatives)");
1137 static_assert(!is_void_v<_Alternative_type>,
"_Tp must not be void");
1138 if (__ptr && __ptr->index() == _Np)
1143 template<
typename _Tp,
typename... _Types>
1144 constexpr add_pointer_t<_Tp>
1145 get_if(variant<_Types...>* __ptr) noexcept
1147 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1148 "T must occur exactly once in alternatives");
1149 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1150 return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(
1154 template<
typename _Tp,
typename... _Types>
1155 constexpr add_pointer_t<const _Tp>
1156 get_if(
const variant<_Types...>* __ptr) noexcept
1158 static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
1159 "T must occur exactly once in alternatives");
1160 static_assert(!is_void_v<_Tp>,
"_Tp must not be void");
1161 return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(
1165 struct monostate { };
1167 #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \
1168 template<typename... _Types> \
1169 constexpr bool operator __OP(const variant<_Types...>& __lhs, \
1170 const variant<_Types...>& __rhs) \
1172 bool __ret = true; \
1173 __detail::__variant::__raw_idx_visit( \
1174 [&__ret, &__lhs] (auto&& __rhs_mem, auto __rhs_index) mutable \
1176 if constexpr (__rhs_index != variant_npos) \
1178 if (__lhs.index() == __rhs_index) \
1180 auto& __this_mem = std::get<__rhs_index>(__lhs); \
1181 __ret = __this_mem __OP __rhs_mem; \
1184 __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \
1187 __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \
1192 _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less)
1193 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal)
1194 _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal)
1195 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal)
1196 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal)
1197 _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater)
1199 #undef _VARIANT_RELATION_FUNCTION_TEMPLATE
1201 constexpr
bool operator==(monostate, monostate) noexcept {
return true; }
1203 #ifdef __cpp_lib_three_way_comparison
1204 template<
typename... _Types>
1205 requires (three_way_comparable<_Types> && ...)
1207 common_comparison_category_t<compare_three_way_result_t<_Types>...>
1208 operator<=>(const variant<_Types...>& __v, const variant<_Types...>& __w)
1210 common_comparison_category_t<compare_three_way_result_t<_Types>...> __ret
1211 = strong_ordering::equal;
1213 __detail::__variant::__raw_idx_visit(
1214 [&__ret, &__v] (
auto&& __w_mem,
auto __w_index)
mutable
1216 if constexpr (__w_index != variant_npos)
1218 if (__v.index() == __w_index)
1220 auto& __this_mem = std::get<__w_index>(__v);
1221 __ret = __this_mem <=> __w_mem;
1225 __ret = (__v.index() + 1) <=> (__w_index + 1);
1230 constexpr strong_ordering
1231 operator<=>(monostate, monostate) noexcept {
return strong_ordering::equal; }
1233 constexpr
bool operator!=(monostate, monostate) noexcept {
return false; }
1234 constexpr
bool operator<(monostate, monostate) noexcept {
return false; }
1235 constexpr
bool operator>(monostate, monostate) noexcept {
return false; }
1236 constexpr
bool operator<=(monostate, monostate) noexcept {
return true; }
1237 constexpr
bool operator>=(monostate, monostate) noexcept {
return true; }
1240 template<
typename _Visitor,
typename... _Variants>
1241 constexpr decltype(
auto) visit(_Visitor&&, _Variants&&...);
1243 template<typename... _Types>
1244 inline
enable_if_t<(is_move_constructible_v<_Types> && ...)
1246 swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs)
1247 noexcept(noexcept(__lhs.swap(__rhs)))
1248 { __lhs.swap(__rhs); }
1250 template<
typename... _Types>
1251 enable_if_t<!((is_move_constructible_v<_Types> && ...)
1252 && (is_swappable_v<_Types> && ...))>
1253 swap(variant<_Types...>&, variant<_Types...>&) =
delete;
1255 class bad_variant_access :
public exception
1258 bad_variant_access() noexcept { }
1260 const char* what() const noexcept
override
1261 {
return _M_reason; }
1264 bad_variant_access(
const char* __reason) noexcept : _M_reason(__reason) { }
1267 const char* _M_reason =
"bad variant access";
1269 friend void __throw_bad_variant_access(
const char* __what);
1274 __throw_bad_variant_access(
const char* __what)
1275 { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); }
1278 __throw_bad_variant_access(
bool __valueless)
1280 if (__valueless) [[__unlikely__]]
1281 __throw_bad_variant_access(
"std::get: variant is valueless");
1283 __throw_bad_variant_access(
"std::get: wrong index for variant");
1286 template<
typename... _Types>
1288 :
private __detail::__variant::_Variant_base<_Types...>,
1289 private _Enable_default_constructor<
1290 __detail::__variant::_Traits<_Types...>::_S_default_ctor,
1291 variant<_Types...>>,
1292 private _Enable_copy_move<
1293 __detail::__variant::_Traits<_Types...>::_S_copy_ctor,
1294 __detail::__variant::_Traits<_Types...>::_S_copy_assign,
1295 __detail::__variant::_Traits<_Types...>::_S_move_ctor,
1296 __detail::__variant::_Traits<_Types...>::_S_move_assign,
1300 template <
typename... _UTypes,
typename _Tp>
1301 friend decltype(
auto) __variant_cast(_Tp&&);
1302 template<
size_t _Np, typename _Variant, typename... _Args>
1303 friend
void __variant_construct_by_index(_Variant& __v,
1306 static_assert(sizeof...(_Types) > 0,
1307 "variant must have at least one alternative");
1308 static_assert(!(std::is_reference_v<_Types> || ...),
1309 "variant must have no reference alternative");
1310 static_assert(!(std::is_void_v<_Types> || ...),
1311 "variant must have no
void alternative");
1313 using _Base = __detail::__variant::_Variant_base<_Types...>;
1314 using _Default_ctor_enabler =
1315 _Enable_default_constructor<
1316 __detail::__variant::_Traits<_Types...>::_S_default_ctor,
1317 variant<_Types...>>;
1319 template<typename _Tp>
1320 static constexpr
bool __not_self
1321 = !is_same_v<__remove_cvref_t<_Tp>, variant>;
1323 template<typename _Tp>
1324 static constexpr
bool
1325 __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>;
1327 template<typename _Tp>
1328 static constexpr
size_t __accepted_index
1329 = __detail::__variant::__accepted_index<_Tp, variant>::value;
1331 template<
size_t _Np, typename =
enable_if_t<(_Np < sizeof...(_Types))>>
1332 using __to_type = variant_alternative_t<_Np, variant>;
1334 template<typename _Tp, typename =
enable_if_t<__not_self<_Tp>>>
1335 using __accepted_type = __to_type<__accepted_index<_Tp>>;
1337 template<typename _Tp>
1338 static constexpr
size_t __index_of =
1339 __detail::__variant::__index_of_v<_Tp, _Types...>;
1341 using _Traits = __detail::__variant::_Traits<_Types...>;
1343 template<typename _Tp>
1345 template<
typename _Tp>
1346 struct __is_in_place_tag<in_place_type_t<_Tp>> :
true_type { };
1347 template<
size_t _Np>
1348 struct __is_in_place_tag<in_place_index_t<_Np>> :
true_type { };
1350 template<
typename _Tp>
1351 static constexpr
bool __not_in_place_tag
1352 = !__is_in_place_tag<__remove_cvref_t<_Tp>>::value;
1355 variant() =
default;
1356 variant(
const variant& __rhs) =
default;
1357 variant(variant&&) =
default;
1358 variant& operator=(
const variant&) =
default;
1359 variant& operator=(variant&&) =
default;
1360 ~variant() =
default;
1362 template<
typename _Tp,
1365 typename _Tj = __accepted_type<_Tp&&>,
1367 && is_constructible_v<_Tj, _Tp>>>
1370 noexcept(is_nothrow_constructible_v<_Tj, _Tp>)
1371 : variant(in_place_index<__accepted_index<_Tp>>,
1375 template<
typename _Tp,
typename... _Args,
1376 typename = enable_if_t<__exactly_once<_Tp>
1377 && is_constructible_v<_Tp, _Args...>>>
1379 variant(in_place_type_t<_Tp>, _Args&&... __args)
1380 : variant(in_place_index<__index_of<_Tp>>,
1381 std::
forward<_Args>(__args)...)
1384 template<
typename _Tp,
typename _Up,
typename... _Args,
1385 typename = enable_if_t<__exactly_once<_Tp>
1386 && is_constructible_v<_Tp,
1387 initializer_list<_Up>&, _Args...>>>
1389 variant(in_place_type_t<_Tp>, initializer_list<_Up> __il,
1391 : variant(in_place_index<__index_of<_Tp>>, __il,
1392 std::
forward<_Args>(__args)...)
1395 template<
size_t _Np,
typename... _Args,
1396 typename _Tp = __to_type<_Np>,
1397 typename =
enable_if_t<is_constructible_v<_Tp, _Args...>>>
1399 variant(in_place_index_t<_Np>, _Args&&... __args)
1400 : _Base(in_place_index<_Np>, std::
forward<_Args>(__args)...),
1401 _Default_ctor_enabler(_Enable_default_constructor_tag{})
1404 template<
size_t _Np,
typename _Up,
typename... _Args,
1405 typename _Tp = __to_type<_Np>,
1407 initializer_list<_Up>&,
1410 variant(in_place_index_t<_Np>, initializer_list<_Up> __il,
1412 : _Base(in_place_index<_Np>, __il, std::
forward<_Args>(__args)...),
1413 _Default_ctor_enabler(_Enable_default_constructor_tag{})
1416 template<
typename _Tp>
1417 enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
1418 && is_constructible_v<__accepted_type<_Tp&&>, _Tp>
1419 && is_assignable_v<__accepted_type<_Tp&&>&, _Tp>,
1421 operator=(_Tp&& __rhs)
1422 noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp>
1423 && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp>)
1425 constexpr
auto __index = __accepted_index<_Tp>;
1426 if (index() == __index)
1427 std::get<__index>(*this) = std::forward<_Tp>(__rhs);
1430 using _Tj = __accepted_type<_Tp&&>;
1431 if constexpr (is_nothrow_constructible_v<_Tj, _Tp>
1432 || !is_nothrow_move_constructible_v<_Tj>)
1433 this->emplace<__index>(std::
forward<_Tp>(__rhs));
1435 operator=(variant(std::
forward<_Tp>(__rhs)));
1440 template<typename _Tp, typename... _Args>
1441 enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>,
1443 emplace(_Args&&... __args)
1445 constexpr
size_t __index = __index_of<_Tp>;
1446 return this->emplace<__index>(std::forward<_Args>(__args)...);
1449 template<
typename _Tp,
typename _Up,
typename... _Args>
1450 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>
1451 && __exactly_once<_Tp>,
1453 emplace(initializer_list<_Up> __il, _Args&&... __args)
1455 constexpr
size_t __index = __index_of<_Tp>;
1456 return this->emplace<__index>(__il, std::forward<_Args>(__args)...);
1459 template<
size_t _Np,
typename... _Args>
1460 enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
1462 variant_alternative_t<_Np, variant>&>
1463 emplace(_Args&&... __args)
1465 static_assert(_Np <
sizeof...(_Types),
1466 "The index must be in [0, number of alternatives)");
1467 using type = variant_alternative_t<_Np, variant>;
1470 if constexpr (is_nothrow_constructible_v<type, _Args...>)
1473 __variant_construct_by_index<_Np>(*
this,
1474 std::forward<_Args>(__args)...);
1476 else if constexpr (is_scalar_v<type>)
1479 const type __tmp(std::forward<_Args>(__args)...);
1482 __variant_construct_by_index<_Np>(*
this, __tmp);
1484 else if constexpr (__detail::__variant::_Never_valueless_alt<type>()
1485 && _Traits::_S_move_assign)
1488 variant __tmp(in_place_index<_Np>,
1489 std::forward<_Args>(__args)...);
1500 __variant_construct_by_index<_Np>(*
this,
1501 std::forward<_Args>(__args)...);
1505 this->_M_index = variant_npos;
1506 __throw_exception_again;
1509 return std::get<_Np>(*this);
1512 template<
size_t _Np,
typename _Up,
typename... _Args>
1513 enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>,
1514 initializer_list<_Up>&, _Args...>,
1515 variant_alternative_t<_Np, variant>&>
1516 emplace(initializer_list<_Up> __il, _Args&&... __args)
1518 static_assert(_Np <
sizeof...(_Types),
1519 "The index must be in [0, number of alternatives)");
1520 using type = variant_alternative_t<_Np, variant>;
1523 if constexpr (is_nothrow_constructible_v<type,
1524 initializer_list<_Up>&,
1528 __variant_construct_by_index<_Np>(*
this, __il,
1529 std::forward<_Args>(__args)...);
1531 else if constexpr (__detail::__variant::_Never_valueless_alt<type>()
1532 && _Traits::_S_move_assign)
1535 variant __tmp(in_place_index<_Np>, __il,
1536 std::forward<_Args>(__args)...);
1547 __variant_construct_by_index<_Np>(*
this, __il,
1548 std::forward<_Args>(__args)...);
1552 this->_M_index = variant_npos;
1553 __throw_exception_again;
1556 return std::get<_Np>(*this);
1559 constexpr
bool valueless_by_exception() const noexcept
1560 {
return !this->_M_valid(); }
1562 constexpr
size_t index() const noexcept
1564 using __index_type =
typename _Base::__index_type;
1565 if constexpr (__detail::__variant::__never_valueless<_Types...>())
1566 return this->_M_index;
1567 else if constexpr (sizeof...(_Types) <= __index_type(-1) / 2)
1570 return
size_t(__index_type(this->_M_index + 1)) - 1;
1574 swap(variant& __rhs)
1575 noexcept((__is_nothrow_swappable<_Types>::value && ...)
1576 && is_nothrow_move_constructible_v<variant>)
1578 __detail::__variant::__raw_idx_visit(
1579 [
this, &__rhs](
auto&& __rhs_mem,
auto __rhs_index)
mutable
1581 if constexpr (__rhs_index != variant_npos)
1583 if (this->index() == __rhs_index)
1586 std::get<__rhs_index>(*this);
1588 swap(__this_mem, __rhs_mem);
1592 if (!this->valueless_by_exception()) [[__likely__]]
1596 this->_M_destructive_move(__rhs_index,
1601 this->_M_destructive_move(__rhs_index,
1609 if (!this->valueless_by_exception()) [[__likely__]]
1620 #if defined(__clang__) && __clang_major__ <= 7
1626 template<
size_t _Np,
typename _Vp>
1627 friend constexpr decltype(
auto)
1628 __detail::__variant::__get(_Vp&& __v) noexcept;
1630 template<typename _Vp>
1632 __detail::__variant::__get_storage(_Vp&& __v) noexcept;
1634 #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \
1635 template<typename... _Tp> \
1636 friend constexpr bool \
1637 operator __OP(const variant<_Tp...>& __lhs, \
1638 const variant<_Tp...>& __rhs);
1640 _VARIANT_RELATION_FUNCTION_TEMPLATE(<)
1641 _VARIANT_RELATION_FUNCTION_TEMPLATE(<=)
1642 _VARIANT_RELATION_FUNCTION_TEMPLATE(==)
1643 _VARIANT_RELATION_FUNCTION_TEMPLATE(!=)
1644 _VARIANT_RELATION_FUNCTION_TEMPLATE(>=)
1645 _VARIANT_RELATION_FUNCTION_TEMPLATE(>)
1647 #undef _VARIANT_RELATION_FUNCTION_TEMPLATE
1650 template<
size_t _Np,
typename... _Types>
1651 constexpr variant_alternative_t<_Np, variant<_Types...>>&
1652 get(variant<_Types...>& __v)
1654 static_assert(_Np <
sizeof...(_Types),
1655 "The index must be in [0, number of alternatives)");
1656 if (__v.index() != _Np)
1657 __throw_bad_variant_access(__v.valueless_by_exception());
1658 return __detail::__variant::__get<_Np>(__v);
1661 template<
size_t _Np,
typename... _Types>
1662 constexpr variant_alternative_t<_Np, variant<_Types...>>&&
1663 get(variant<_Types...>&& __v)
1665 static_assert(_Np <
sizeof...(_Types),
1666 "The index must be in [0, number of alternatives)");
1667 if (__v.index() != _Np)
1668 __throw_bad_variant_access(__v.valueless_by_exception());
1669 return __detail::__variant::__get<_Np>(
std::move(__v));
1672 template<
size_t _Np,
typename... _Types>
1673 constexpr
const variant_alternative_t<_Np, variant<_Types...>>&
1674 get(
const variant<_Types...>& __v)
1676 static_assert(_Np <
sizeof...(_Types),
1677 "The index must be in [0, number of alternatives)");
1678 if (__v.index() != _Np)
1679 __throw_bad_variant_access(__v.valueless_by_exception());
1680 return __detail::__variant::__get<_Np>(__v);
1683 template<
size_t _Np,
typename... _Types>
1684 constexpr
const variant_alternative_t<_Np, variant<_Types...>>&&
1685 get(
const variant<_Types...>&& __v)
1687 static_assert(_Np <
sizeof...(_Types),
1688 "The index must be in [0, number of alternatives)");
1689 if (__v.index() != _Np)
1690 __throw_bad_variant_access(__v.valueless_by_exception());
1691 return __detail::__variant::__get<_Np>(
std::move(__v));
1694 template<
typename _Result_type,
typename _Visitor,
typename... _Variants>
1695 constexpr decltype(
auto)
1696 __do_visit(_Visitor&& __visitor, _Variants&&... __variants)
1698 constexpr
auto& __vtable = __detail::__variant::__gen_vtable<
1699 _Result_type, _Visitor&&, _Variants&&...>::_S_vtable;
1701 auto __func_ptr = __vtable._M_access(__variants.index()...);
1702 return (*__func_ptr)(std::forward<_Visitor>(__visitor),
1703 std::forward<_Variants>(__variants)...);
1706 template<
typename _Visitor,
typename... _Variants>
1707 constexpr decltype(
auto)
1708 visit(_Visitor&& __visitor, _Variants&&... __variants)
1710 if ((__variants.valueless_by_exception() || ...))
1711 __throw_bad_variant_access(
"std::visit: variant is valueless");
1713 using _Result_type = std::invoke_result_t<_Visitor,
1714 decltype(std::get<0>(std::declval<_Variants>()))...>;
1716 using _Tag = __detail::__variant::__deduce_visit_result<_Result_type>;
1718 return std::__do_visit<_Tag>(std::forward<_Visitor>(__visitor),
1719 std::forward<_Variants>(__variants)...);
1722 #if __cplusplus > 201703L
1723 template<
typename _Res,
typename _Visitor,
typename... _Variants>
1725 visit(_Visitor&& __visitor, _Variants&&... __variants)
1727 if ((__variants.valueless_by_exception() || ...))
1728 __throw_bad_variant_access(
"std::visit<R>: variant is valueless");
1730 return std::__do_visit<_Res>(std::forward<_Visitor>(__visitor),
1731 std::forward<_Variants>(__variants)...);
1735 template<bool,
typename... _Types>
1736 struct __variant_hash_call_base_impl
1739 operator()(
const variant<_Types...>& __t)
const
1740 noexcept((is_nothrow_invocable_v<hash<decay_t<_Types>>, _Types> && ...))
1743 __detail::__variant::__raw_visit(
1744 [&__t, &__ret](
auto&& __t_mem)
mutable
1746 using _Type = __remove_cvref_t<decltype(__t_mem)>;
1747 if constexpr (!is_same_v<_Type,
1748 __detail::__variant::__variant_cookie>)
1749 __ret = std::hash<
size_t>{}(__t.index())
1758 template<
typename... _Types>
1759 struct __variant_hash_call_base_impl<false, _Types...> {};
1761 template<
typename... _Types>
1762 using __variant_hash_call_base =
1763 __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>::
1764 __enable_hash_call &&...), _Types...>;
1766 template<
typename... _Types>
1767 struct hash<variant<_Types...>>
1768 :
private __detail::__variant::_Variant_hash_base<
1769 variant<_Types...>, std::index_sequence_for<_Types...>>,
1770 public __variant_hash_call_base<_Types...>
1772 using result_type [[__deprecated__]] = size_t;
1773 using argument_type [[__deprecated__]] = variant<_Types...>;
1777 struct hash<monostate>
1779 using result_type [[__deprecated__]] = size_t;
1780 using argument_type [[__deprecated__]] = monostate;
1783 operator()(
const monostate&) const noexcept
1785 constexpr
size_t __magic_monostate_hash = -7777;
1786 return __magic_monostate_hash;
1790 template<
typename... _Types>
1791 struct __is_fast_hash<hash<variant<_Types...>>>
1792 : bool_constant<(__is_fast_hash<_Types>::value && ...)>
1795 _GLIBCXX_END_NAMESPACE_VERSION
1800 #endif // _GLIBCXX_VARIANT
constexpr _Tp * addressof(_Tp &__r) noexcept
Returns the actual address of the object or function referenced by r, even in the presence of an over...
integer_sequence< size_t, _Idx...> index_sequence
Alias template index_sequence.
make_integer_sequence< size_t, _Num > make_index_sequence
Alias template make_index_sequence.
Class template integer_sequence.
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
void void_t
A metafunction that always yields void, used for detecting valid types.
typename make_signed< _Tp >::type make_signed_t
Alias template for make_signed.
constexpr bool is_swappable_v
is_swappable_v
typename add_pointer< _Tp >::type add_pointer_t
Alias template for add_pointer.
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Primary class template hash.
typename remove_reference< _Tp >::type remove_reference_t
Alias template for remove_reference.
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
typename enable_if< _Cond, _Tp >::type enable_if_t
Alias template for enable_if.
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.