// -*- C++ -*- // Copyright (C) 2016-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // . /** @file variant * This is the C++ Library header. */ #ifndef _GLIBCXX_VARIANT #define _GLIBCXX_VARIANT 1 #pragma GCC system_header #if __cplusplus >= 201703L #include #include #include #include #include #include #include #include #include #include #include #include namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace __detail { namespace __variant { template struct _Nth_type; template struct _Nth_type<_Np, _First, _Rest...> : _Nth_type<_Np-1, _Rest...> { }; template struct _Nth_type<0, _First, _Rest...> { using type = _First; }; } // namespace __variant } // namespace __detail #define __cpp_lib_variant 201606L template class tuple; template class variant; template struct hash; template struct variant_size; template struct variant_size : variant_size<_Variant> {}; template struct variant_size : variant_size<_Variant> {}; template struct variant_size : variant_size<_Variant> {}; template struct variant_size> : std::integral_constant {}; template inline constexpr size_t variant_size_v = variant_size<_Variant>::value; template struct variant_alternative; template struct variant_alternative<_Np, variant<_First, _Rest...>> : variant_alternative<_Np-1, variant<_Rest...>> {}; template struct variant_alternative<0, variant<_First, _Rest...>> { using type = _First; }; template using variant_alternative_t = typename variant_alternative<_Np, _Variant>::type; template struct variant_alternative<_Np, const _Variant> { using type = add_const_t>; }; template struct variant_alternative<_Np, volatile _Variant> { using type = add_volatile_t>; }; template struct variant_alternative<_Np, const volatile _Variant> { using type = add_cv_t>; }; inline constexpr size_t variant_npos = -1; template constexpr variant_alternative_t<_Np, variant<_Types...>>& get(variant<_Types...>&); template constexpr variant_alternative_t<_Np, variant<_Types...>>&& get(variant<_Types...>&&); template constexpr variant_alternative_t<_Np, variant<_Types...>> const& get(const variant<_Types...>&); template constexpr variant_alternative_t<_Np, variant<_Types...>> const&& get(const variant<_Types...>&&); namespace __detail { namespace __variant { // Returns the first apparence of _Tp in _Types. // Returns sizeof...(_Types) if _Tp is not in _Types. template struct __index_of : std::integral_constant {}; template inline constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value; template struct __index_of<_Tp, _First, _Rest...> : std::integral_constant ? 0 : __index_of_v<_Tp, _Rest...> + 1> {}; // _Uninitialized is guaranteed to be a literal type, even if T is not. // We have to do this, because [basic.types]p10.5.3 (n4606) is not implemented // yet. When it's implemented, _Uninitialized can be changed to the alias // to T, therefore equivalent to being removed entirely. // // Another reason we may not want to remove _Uninitialzied may be that, we // want _Uninitialized to be trivially destructible, no matter whether T // is; but we will see. template> struct _Uninitialized; template struct _Uninitialized<_Type, true> { template constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args) : _M_storage(std::forward<_Args>(__args)...) { } constexpr const _Type& _M_get() const & { return _M_storage; } constexpr _Type& _M_get() & { return _M_storage; } constexpr const _Type&& _M_get() const && { return std::move(_M_storage); } constexpr _Type&& _M_get() && { return std::move(_M_storage); } _Type _M_storage; }; template struct _Uninitialized<_Type, false> { template constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args) { ::new (&_M_storage) _Type(std::forward<_Args>(__args)...); } const _Type& _M_get() const & { return *_M_storage._M_ptr(); } _Type& _M_get() & { return *_M_storage._M_ptr(); } const _Type&& _M_get() const && { return std::move(*_M_storage._M_ptr()); } _Type&& _M_get() && { return std::move(*_M_storage._M_ptr()); } __gnu_cxx::__aligned_membuf<_Type> _M_storage; }; template _Ref __ref_cast(void* __ptr) { return static_cast<_Ref>(*static_cast*>(__ptr)); } template constexpr decltype(auto) __get(in_place_index_t<0>, _Union&& __u) { return std::forward<_Union>(__u)._M_first._M_get(); } template constexpr decltype(auto) __get(in_place_index_t<_Np>, _Union&& __u) { return __variant::__get(in_place_index<_Np-1>, std::forward<_Union>(__u)._M_rest); } // Returns the typed storage for __v. template constexpr decltype(auto) __get(_Variant&& __v) { return __variant::__get(std::in_place_index<_Np>, std::forward<_Variant>(__v)._M_u); } // Various functions as "vtable" entries, where those vtables are used by // polymorphic operations. template void __erased_ctor(void* __lhs, void* __rhs) { using _Type = remove_reference_t<_Lhs>; ::new (__lhs) _Type(__variant::__ref_cast<_Rhs>(__rhs)); } template void __erased_dtor(_Variant&& __v) { std::_Destroy(std::__addressof(__variant::__get<_Np>(__v))); } template void __erased_assign(void* __lhs, void* __rhs) { __variant::__ref_cast<_Lhs>(__lhs) = __variant::__ref_cast<_Rhs>(__rhs); } template void __erased_swap(void* __lhs, void* __rhs) { using std::swap; swap(__variant::__ref_cast<_Lhs>(__lhs), __variant::__ref_cast<_Rhs>(__rhs)); } #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ template \ constexpr bool \ __erased_##__NAME(const _Variant& __lhs, const _Variant& __rhs) \ { \ return __variant::__get<_Np>(std::forward<_Variant>(__lhs)) \ __OP __variant::__get<_Np>(std::forward<_Variant>(__rhs)); \ } _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) #undef _VARIANT_RELATION_FUNCTION_TEMPLATE template size_t __erased_hash(void* __t) { return std::hash>>{}( __variant::__ref_cast<_Tp>(__t)); } template struct _Traits { static constexpr bool _S_default_ctor = is_default_constructible_v::type>; static constexpr bool _S_copy_ctor = (is_copy_constructible_v<_Types> && ...); static constexpr bool _S_move_ctor = (is_move_constructible_v<_Types> && ...); static constexpr bool _S_copy_assign = _S_copy_ctor && _S_move_ctor && (is_copy_assignable_v<_Types> && ...); static constexpr bool _S_move_assign = _S_move_ctor && (is_move_assignable_v<_Types> && ...); static constexpr bool _S_trivial_dtor = (is_trivially_destructible_v<_Types> && ...); static constexpr bool _S_trivial_copy_ctor = (is_trivially_copy_constructible_v<_Types> && ...); static constexpr bool _S_trivial_move_ctor = (is_trivially_move_constructible_v<_Types> && ...); static constexpr bool _S_trivial_copy_assign = _S_trivial_dtor && (is_trivially_copy_assignable_v<_Types> && ...); static constexpr bool _S_trivial_move_assign = _S_trivial_dtor && (is_trivially_move_assignable_v<_Types> && ...); // The following nothrow traits are for non-trivial SMFs. Trivial SMFs // are always nothrow. static constexpr bool _S_nothrow_default_ctor = is_nothrow_default_constructible_v< typename _Nth_type<0, _Types...>::type>; static constexpr bool _S_nothrow_copy_ctor = false; static constexpr bool _S_nothrow_move_ctor = (is_nothrow_move_constructible_v<_Types> && ...); static constexpr bool _S_nothrow_copy_assign = false; static constexpr bool _S_nothrow_move_assign = _S_nothrow_move_ctor && (is_nothrow_move_assignable_v<_Types> && ...); }; // Defines members and ctors. template union _Variadic_union { }; template union _Variadic_union<_First, _Rest...> { constexpr _Variadic_union() : _M_rest() { } template constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args) : _M_first(in_place_index<0>, std::forward<_Args>(__args)...) { } template constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args) : _M_rest(in_place_index<_Np-1>, std::forward<_Args>(__args)...) { } _Uninitialized<_First> _M_first; _Variadic_union<_Rest...> _M_rest; }; // Defines index and the dtor, possibly trivial. template struct _Variant_storage; template using __select_index = typename __select_int::_Select_int_base::type::value_type; template struct _Variant_storage { template static constexpr void (*_S_vtable[])(const _Variant_storage&) = { &__erased_dtor... }; constexpr _Variant_storage() : _M_index(variant_npos) { } template constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), _M_index(_Np) { } template constexpr void _M_reset_impl(std::index_sequence<__indices...>) { if (_M_index != __index_type(variant_npos)) _S_vtable<__indices...>[_M_index](*this); } void _M_reset() { _M_reset_impl(std::index_sequence_for<_Types...>{}); _M_index = variant_npos; } ~_Variant_storage() { _M_reset(); } void* _M_storage() const { return const_cast(static_cast( std::addressof(_M_u))); } constexpr bool _M_valid() const noexcept { return this->_M_index != __index_type(variant_npos); } _Variadic_union<_Types...> _M_u; using __index_type = __select_index<_Types...>; __index_type _M_index; }; template struct _Variant_storage { constexpr _Variant_storage() : _M_index(variant_npos) { } template constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), _M_index(_Np) { } void _M_reset() { _M_index = variant_npos; } void* _M_storage() const { return const_cast(static_cast( std::addressof(_M_u))); } constexpr bool _M_valid() const noexcept { return this->_M_index != __index_type(variant_npos); } _Variadic_union<_Types...> _M_u; using __index_type = __select_index<_Types...>; __index_type _M_index; }; template using _Variant_storage_alias = _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>; // The following are (Copy|Move) (ctor|assign) layers for forwarding // triviality and handling non-trivial SMF behaviors. template struct _Copy_ctor_base : _Variant_storage_alias<_Types...> { using _Base = _Variant_storage_alias<_Types...>; using _Base::_Base; _Copy_ctor_base(const _Copy_ctor_base& __rhs) noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor) { if (__rhs._M_valid()) { static constexpr void (*_S_vtable[])(void*, void*) = { &__erased_ctor<_Types&, const _Types&>... }; _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); this->_M_index = __rhs._M_index; } } _Copy_ctor_base(_Copy_ctor_base&&) = default; _Copy_ctor_base& operator=(const _Copy_ctor_base&) = default; _Copy_ctor_base& operator=(_Copy_ctor_base&&) = default; }; template struct _Copy_ctor_base : _Variant_storage_alias<_Types...> { using _Base = _Variant_storage_alias<_Types...>; using _Base::_Base; }; template using _Copy_ctor_alias = _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>; template struct _Move_ctor_base : _Copy_ctor_alias<_Types...> { using _Base = _Copy_ctor_alias<_Types...>; using _Base::_Base; _Move_ctor_base(_Move_ctor_base&& __rhs) noexcept(_Traits<_Types...>::_S_nothrow_move_ctor) { if (__rhs._M_valid()) { static constexpr void (*_S_vtable[])(void*, void*) = { &__erased_ctor<_Types&, _Types&&>... }; _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); this->_M_index = __rhs._M_index; } } void _M_destructive_move(_Move_ctor_base&& __rhs) { this->~_Move_ctor_base(); __try { ::new (this) _Move_ctor_base(std::move(__rhs)); } __catch (...) { this->_M_index = variant_npos; __throw_exception_again; } } _Move_ctor_base(const _Move_ctor_base&) = default; _Move_ctor_base& operator=(const _Move_ctor_base&) = default; _Move_ctor_base& operator=(_Move_ctor_base&&) = default; }; template struct _Move_ctor_base : _Copy_ctor_alias<_Types...> { using _Base = _Copy_ctor_alias<_Types...>; using _Base::_Base; void _M_destructive_move(_Move_ctor_base&& __rhs) { this->~_Move_ctor_base(); ::new (this) _Move_ctor_base(std::move(__rhs)); } }; template using _Move_ctor_alias = _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>; template struct _Copy_assign_base : _Move_ctor_alias<_Types...> { using _Base = _Move_ctor_alias<_Types...>; using _Base::_Base; _Copy_assign_base& operator=(const _Copy_assign_base& __rhs) noexcept(_Traits<_Types...>::_S_nothrow_copy_assign) { if (this->_M_index == __rhs._M_index) { if (__rhs._M_valid()) { static constexpr void (*_S_vtable[])(void*, void*) = { &__erased_assign<_Types&, const _Types&>... }; _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); } } else { _Copy_assign_base __tmp(__rhs); this->_M_destructive_move(std::move(__tmp)); } __glibcxx_assert(this->_M_index == __rhs._M_index); return *this; } _Copy_assign_base(const _Copy_assign_base&) = default; _Copy_assign_base(_Copy_assign_base&&) = default; _Copy_assign_base& operator=(_Copy_assign_base&&) = default; }; template struct _Copy_assign_base : _Move_ctor_alias<_Types...> { using _Base = _Move_ctor_alias<_Types...>; using _Base::_Base; }; template using _Copy_assign_alias = _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, _Types...>; template struct _Move_assign_base : _Copy_assign_alias<_Types...> { using _Base = _Copy_assign_alias<_Types...>; using _Base::_Base; _Move_assign_base& operator=(_Move_assign_base&& __rhs) noexcept(_Traits<_Types...>::_S_nothrow_move_assign) { if (this->_M_index == __rhs._M_index) { if (__rhs._M_valid()) { static constexpr void (*_S_vtable[])(void*, void*) = { &__erased_assign<_Types&, _Types&&>... }; _S_vtable[__rhs._M_index] (this->_M_storage(), __rhs._M_storage()); } } else { _Move_assign_base __tmp(std::move(__rhs)); this->_M_destructive_move(std::move(__tmp)); } __glibcxx_assert(this->_M_index == __rhs._M_index); return *this; } _Move_assign_base(const _Move_assign_base&) = default; _Move_assign_base(_Move_assign_base&&) = default; _Move_assign_base& operator=(const _Move_assign_base&) = default; }; template struct _Move_assign_base : _Copy_assign_alias<_Types...> { using _Base = _Copy_assign_alias<_Types...>; using _Base::_Base; }; template using _Move_assign_alias = _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, _Types...>; template struct _Variant_base : _Move_assign_alias<_Types...> { using _Base = _Move_assign_alias<_Types...>; constexpr _Variant_base() noexcept(_Traits<_Types...>::_S_nothrow_default_ctor) : _Variant_base(in_place_index<0>) { } template constexpr explicit _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args) : _Base(__i, std::forward<_Args>(__args)...) { } _Variant_base(const _Variant_base&) = default; _Variant_base(_Variant_base&&) = default; _Variant_base& operator=(const _Variant_base&) = default; _Variant_base& operator=(_Variant_base&&) = default; }; // For how many times does _Tp appear in _Tuple? template struct __tuple_count; template inline constexpr size_t __tuple_count_v = __tuple_count<_Tp, _Tuple>::value; template struct __tuple_count<_Tp, tuple<_Types...>> : integral_constant { }; template struct __tuple_count<_Tp, tuple<_First, _Rest...>> : integral_constant< size_t, __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { }; // TODO: Reuse this in ? template inline constexpr bool __exactly_once = __tuple_count_v<_Tp, tuple<_Types...>> == 1; // Takes _Types and create an overloaded _S_fun for each type. // If a type appears more than once in _Types, create only one overload. template struct __overload_set { static void _S_fun(); }; template struct __overload_set<_First, _Rest...> : __overload_set<_Rest...> { using __overload_set<_Rest...>::_S_fun; static integral_constant _S_fun(_First); }; template struct __overload_set : __overload_set<_Rest...> { using __overload_set<_Rest...>::_S_fun; }; // Helper for variant(_Tp&&) and variant::operator=(_Tp&&). // __accepted_index maps the arbitrary _Tp to an alternative type in _Variant. template struct __accepted_index { static constexpr size_t value = variant_npos; }; template struct __accepted_index< _Tp, variant<_Types...>, decltype(__overload_set<_Types...>::_S_fun(std::declval<_Tp>()), std::declval())> { static constexpr size_t value = sizeof...(_Types) - 1 - decltype(__overload_set<_Types...>:: _S_fun(std::declval<_Tp>()))::value; }; // Returns the raw storage for __v. template void* __get_storage(_Variant&& __v) { return __v._M_storage(); } // Used for storing multi-dimensional vtable. template struct _Multi_array { constexpr const _Tp& _M_access() const { return _M_data; } _Tp _M_data; }; template struct _Multi_array<_Tp, __first, __rest...> { template constexpr const _Tp& _M_access(size_t __first_index, _Args... __rest_indices) const { return _M_arr[__first_index]._M_access(__rest_indices...); } _Multi_array<_Tp, __rest...> _M_arr[__first]; }; // Creates a multi-dimensional vtable recursively. // // For example, // visit([](auto, auto){}, // variant(), // typedef'ed as V1 // variant()) // typedef'ed as V2 // will trigger instantiations of: // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<0>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<0, 0>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<0, 1>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<0, 2>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<1>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<1, 0>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<1, 1>> // __gen_vtable_impl<_Multi_array, // tuple, std::index_sequence<1, 2>> // The returned multi-dimensional vtable can be fast accessed by the visitor // using index calculation. template struct __gen_vtable_impl; template struct __gen_vtable_impl< _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>, tuple<_Variants...>, std::index_sequence<__indices...>> { using _Next = remove_reference_t::type>; using _Array_type = _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>; static constexpr _Array_type _S_apply() { _Array_type __vtable{}; _S_apply_all_alts( __vtable, make_index_sequence>()); return __vtable; } template static constexpr void _S_apply_all_alts(_Array_type& __vtable, std::index_sequence<__var_indices...>) { (_S_apply_single_alt<__var_indices>( __vtable._M_arr[__var_indices]), ...); } template static constexpr void _S_apply_single_alt(_Tp& __element) { using _Alternative = variant_alternative_t<__index, _Next>; __element = __gen_vtable_impl< remove_reference_t, tuple<_Variants...>, std::index_sequence<__indices..., __index>>::_S_apply(); } }; template struct __gen_vtable_impl< _Multi_array<_Result_type (*)(_Visitor, _Variants...)>, tuple<_Variants...>, std::index_sequence<__indices...>> { using _Array_type = _Multi_array<_Result_type (*)(_Visitor&&, _Variants...)>; static constexpr decltype(auto) __visit_invoke(_Visitor&& __visitor, _Variants... __vars) { return std::__invoke(std::forward<_Visitor>(__visitor), __variant::__get<__indices>(std::forward<_Variants>(__vars))...); } static constexpr auto _S_apply() { return _Array_type{&__visit_invoke}; } }; template struct __gen_vtable { using _Func_ptr = _Result_type (*)(_Visitor&&, _Variants...); using _Array_type = _Multi_array<_Func_ptr, variant_size_v>...>; static constexpr _Array_type _S_apply() { return __gen_vtable_impl<_Array_type, tuple<_Variants...>, std::index_sequence<>>::_S_apply(); } static constexpr auto _S_vtable = _S_apply(); }; template struct _Base_dedup : public _Tp { }; template struct _Variant_hash_base; template struct _Variant_hash_base, std::index_sequence<__indices...>> : _Base_dedup<__indices, __poison_hash>>... { }; } // namespace __variant } // namespace __detail template constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>; } template constexpr _Tp& get(variant<_Types...>& __v) { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); } template constexpr _Tp&& get(variant<_Types...>&& __v) { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( std::move(__v)); } template constexpr const _Tp& get(const variant<_Types...>& __v) { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); } template constexpr const _Tp&& get(const variant<_Types...>&& __v) { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( std::move(__v)); } template constexpr add_pointer_t>> get_if(variant<_Types...>* __ptr) noexcept { using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); if (__ptr && __ptr->index() == _Np) return &__detail::__variant::__get<_Np>(*__ptr); return nullptr; } template constexpr add_pointer_t>> get_if(const variant<_Types...>* __ptr) noexcept { using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); if (__ptr && __ptr->index() == _Np) return &__detail::__variant::__get<_Np>(*__ptr); return nullptr; } template constexpr add_pointer_t<_Tp> get_if(variant<_Types...>* __ptr) noexcept { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( __ptr); } template constexpr add_pointer_t get_if(const variant<_Types...>* __ptr) noexcept { static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, "T should occur for exactly once in alternatives"); static_assert(!is_void_v<_Tp>, "_Tp should not be void"); return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( __ptr); } struct monostate { }; #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ template \ constexpr bool operator __OP(const variant<_Types...>& __lhs, \ const variant<_Types...>& __rhs) \ { \ return __lhs._M_##__NAME(__rhs, std::index_sequence_for<_Types...>{}); \ } \ \ constexpr bool operator __OP(monostate, monostate) noexcept \ { return 0 __OP 0; } _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) #undef _VARIANT_RELATION_FUNCTION_TEMPLATE template constexpr decltype(auto) visit(_Visitor&&, _Variants&&...); template inline enable_if_t<(is_move_constructible_v<_Types> && ...) && (is_swappable_v<_Types> && ...)> swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) { __lhs.swap(__rhs); } template enable_if_t && ...) && (is_swappable_v<_Types> && ...))> swap(variant<_Types...>&, variant<_Types...>&) = delete; class bad_variant_access : public exception { public: bad_variant_access() noexcept : _M_reason("Unknown reason") { } const char* what() const noexcept override { return _M_reason; } private: bad_variant_access(const char* __reason) : _M_reason(__reason) { } const char* _M_reason; friend void __throw_bad_variant_access(const char* __what); }; inline void __throw_bad_variant_access(const char* __what) { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); } template class variant : private __detail::__variant::_Variant_base<_Types...>, private _Enable_default_constructor< __detail::__variant::_Traits<_Types...>::_S_default_ctor, variant<_Types...>>, private _Enable_copy_move< __detail::__variant::_Traits<_Types...>::_S_copy_ctor, __detail::__variant::_Traits<_Types...>::_S_copy_assign, __detail::__variant::_Traits<_Types...>::_S_move_ctor, __detail::__variant::_Traits<_Types...>::_S_move_assign, variant<_Types...>> { private: static_assert(sizeof...(_Types) > 0, "variant must have at least one alternative"); static_assert(!(std::is_reference_v<_Types> || ...), "variant must have no reference alternative"); static_assert(!(std::is_void_v<_Types> || ...), "variant must have no void alternative"); using _Base = __detail::__variant::_Variant_base<_Types...>; using _Default_ctor_enabler = _Enable_default_constructor< __detail::__variant::_Traits<_Types...>::_S_default_ctor, variant<_Types...>>; template static constexpr bool __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>; template static constexpr size_t __accepted_index = __detail::__variant::__accepted_index<_Tp&&, variant>::value; template struct __to_type_impl; template struct __to_type_impl<_Np, true> { using type = variant_alternative_t<_Np, variant>; }; template using __to_type = typename __to_type_impl<_Np>::type; template using __accepted_type = __to_type<__accepted_index<_Tp>>; template static constexpr size_t __index_of = __detail::__variant::__index_of_v<_Tp, _Types...>; using _Traits = __detail::__variant::_Traits<_Types...>; template struct __is_in_place_tag : false_type { }; template struct __is_in_place_tag> : true_type { }; template struct __is_in_place_tag> : true_type { }; template static constexpr bool __not_in_place_tag = !__is_in_place_tag>::value; public: variant() = default; variant(const variant& __rhs) = default; variant(variant&&) = default; variant& operator=(const variant&) = default; variant& operator=(variant&&) = default; ~variant() = default; template, variant>>, typename = enable_if_t<(sizeof...(_Types)>0)>, typename = enable_if_t<__not_in_place_tag<_Tp>>, typename = enable_if_t<__exactly_once<__accepted_type<_Tp&&>> && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>>> constexpr variant(_Tp&& __t) noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>) : variant(in_place_index<__accepted_index<_Tp&&>>, std::forward<_Tp>(__t)) { __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); } template && is_constructible_v<_Tp, _Args&&...>>> constexpr explicit variant(in_place_type_t<_Tp>, _Args&&... __args) : variant(in_place_index<__index_of<_Tp>>, std::forward<_Args>(__args)...) { __glibcxx_assert(holds_alternative<_Tp>(*this)); } template && is_constructible_v< _Tp, initializer_list<_Up>&, _Args&&...>>> constexpr explicit variant(in_place_type_t<_Tp>, initializer_list<_Up> __il, _Args&&... __args) : variant(in_place_index<__index_of<_Tp>>, __il, std::forward<_Args>(__args)...) { __glibcxx_assert(holds_alternative<_Tp>(*this)); } template, _Args&&...>>> constexpr explicit variant(in_place_index_t<_Np>, _Args&&... __args) : _Base(in_place_index<_Np>, std::forward<_Args>(__args)...), _Default_ctor_enabler(_Enable_default_constructor_tag{}) { __glibcxx_assert(index() == _Np); } template, initializer_list<_Up>&, _Args&&...>>> constexpr explicit variant(in_place_index_t<_Np>, initializer_list<_Up> __il, _Args&&... __args) : _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...), _Default_ctor_enabler(_Enable_default_constructor_tag{}) { __glibcxx_assert(index() == _Np); } template enable_if_t<__exactly_once<__accepted_type<_Tp&&>> && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&> && is_assignable_v<__accepted_type<_Tp&&>&, _Tp&&> && !is_same_v, variant>, variant&> operator=(_Tp&& __rhs) noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp&&> && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>) { constexpr auto __index = __accepted_index<_Tp&&>; if (index() == __index) std::get<__index>(*this) = std::forward<_Tp>(__rhs); else this->emplace<__index>(std::forward<_Tp>(__rhs)); __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); return *this; } template enable_if_t && __exactly_once<_Tp>, _Tp&> emplace(_Args&&... __args) { auto& ret = this->emplace<__index_of<_Tp>>(std::forward<_Args>(__args)...); __glibcxx_assert(holds_alternative<_Tp>(*this)); return ret; } template enable_if_t&, _Args...> && __exactly_once<_Tp>, _Tp&> emplace(initializer_list<_Up> __il, _Args&&... __args) { auto& ret = this->emplace<__index_of<_Tp>>(__il, std::forward<_Args>(__args)...); __glibcxx_assert(holds_alternative<_Tp>(*this)); return ret; } template enable_if_t, _Args...>, variant_alternative_t<_Np, variant>&> emplace(_Args&&... __args) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); this->~variant(); __try { ::new (this) variant(in_place_index<_Np>, std::forward<_Args>(__args)...); } __catch (...) { this->_M_index = variant_npos; __throw_exception_again; } __glibcxx_assert(index() == _Np); return std::get<_Np>(*this); } template enable_if_t, initializer_list<_Up>&, _Args...>, variant_alternative_t<_Np, variant>&> emplace(initializer_list<_Up> __il, _Args&&... __args) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); this->~variant(); __try { ::new (this) variant(in_place_index<_Np>, __il, std::forward<_Args>(__args)...); } __catch (...) { this->_M_index = variant_npos; __throw_exception_again; } __glibcxx_assert(index() == _Np); return std::get<_Np>(*this); } constexpr bool valueless_by_exception() const noexcept { return !this->_M_valid(); } constexpr size_t index() const noexcept { if (this->_M_index == typename _Base::__index_type(variant_npos)) return variant_npos; return this->_M_index; } void swap(variant& __rhs) noexcept((__is_nothrow_swappable<_Types>::value && ...) && is_nothrow_move_constructible_v) { if (this->index() == __rhs.index()) { if (this->_M_valid()) { static constexpr void (*_S_vtable[])(void*, void*) = { &__detail::__variant::__erased_swap<_Types&, _Types&>... }; _S_vtable[__rhs._M_index](this->_M_storage(), __rhs._M_storage()); } } else if (!this->_M_valid()) { this->_M_destructive_move(std::move(__rhs)); __rhs._M_reset(); } else if (!__rhs._M_valid()) { __rhs._M_destructive_move(std::move(*this)); this->_M_reset(); } else { auto __tmp = std::move(__rhs); __rhs._M_destructive_move(std::move(*this)); this->_M_destructive_move(std::move(__tmp)); } } private: #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ template \ static constexpr bool \ (*_S_erased_##__NAME[])(const variant&, const variant&) = \ { &__detail::__variant::__erased_##__NAME< \ const variant&, __indices>... }; \ template \ constexpr bool \ _M_##__NAME(const variant& __rhs, \ std::index_sequence<__indices...>) const \ { \ auto __lhs_index = this->index(); \ auto __rhs_index = __rhs.index(); \ if (__lhs_index != __rhs_index || valueless_by_exception()) \ /* Modulo addition. */ \ return __lhs_index + 1 __OP __rhs_index + 1; \ return _S_erased_##__NAME<__indices...>[__lhs_index](*this, __rhs); \ } _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) #undef _VARIANT_RELATION_FUNCTION_TEMPLATE #ifdef __clang__ public: using _Base::_M_u; // See https://bugs.llvm.org/show_bug.cgi?id=31852 private: #endif template friend constexpr decltype(auto) __detail::__variant::__get(_Vp&& __v); template friend void* __detail::__variant::__get_storage(_Vp&& __v); #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \ template \ friend constexpr bool \ operator __OP(const variant<_Tp...>& __lhs, \ const variant<_Tp...>& __rhs); _VARIANT_RELATION_FUNCTION_TEMPLATE(<) _VARIANT_RELATION_FUNCTION_TEMPLATE(<=) _VARIANT_RELATION_FUNCTION_TEMPLATE(==) _VARIANT_RELATION_FUNCTION_TEMPLATE(!=) _VARIANT_RELATION_FUNCTION_TEMPLATE(>=) _VARIANT_RELATION_FUNCTION_TEMPLATE(>) #undef _VARIANT_RELATION_FUNCTION_TEMPLATE }; template constexpr variant_alternative_t<_Np, variant<_Types...>>& get(variant<_Types...>& __v) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); if (__v.index() != _Np) __throw_bad_variant_access("Unexpected index"); return __detail::__variant::__get<_Np>(__v); } template constexpr variant_alternative_t<_Np, variant<_Types...>>&& get(variant<_Types...>&& __v) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); if (__v.index() != _Np) __throw_bad_variant_access("Unexpected index"); return __detail::__variant::__get<_Np>(std::move(__v)); } template constexpr const variant_alternative_t<_Np, variant<_Types...>>& get(const variant<_Types...>& __v) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); if (__v.index() != _Np) __throw_bad_variant_access("Unexpected index"); return __detail::__variant::__get<_Np>(__v); } template constexpr const variant_alternative_t<_Np, variant<_Types...>>&& get(const variant<_Types...>&& __v) { static_assert(_Np < sizeof...(_Types), "The index should be in [0, number of alternatives)"); if (__v.index() != _Np) __throw_bad_variant_access("Unexpected index"); return __detail::__variant::__get<_Np>(std::move(__v)); } template constexpr decltype(auto) visit(_Visitor&& __visitor, _Variants&&... __variants) { if ((__variants.valueless_by_exception() || ...)) __throw_bad_variant_access("Unexpected index"); using _Result_type = decltype(std::forward<_Visitor>(__visitor)( std::get<0>(std::forward<_Variants>(__variants))...)); constexpr auto& __vtable = __detail::__variant::__gen_vtable< _Result_type, _Visitor&&, _Variants&&...>::_S_vtable; auto __func_ptr = __vtable._M_access(__variants.index()...); return (*__func_ptr)(std::forward<_Visitor>(__visitor), std::forward<_Variants>(__variants)...); } template struct __variant_hash_call_base_impl { size_t operator()(const variant<_Types...>& __t) const noexcept((is_nothrow_invocable_v>, _Types> && ...)) { if (!__t.valueless_by_exception()) { namespace __edv = __detail::__variant; static constexpr size_t (*_S_vtable[])(void*) = { &__edv::__erased_hash... }; return hash{}(__t.index()) + _S_vtable[__t.index()](__edv::__get_storage(__t)); } return hash{}(__t.index()); } }; template struct __variant_hash_call_base_impl {}; template using __variant_hash_call_base = __variant_hash_call_base_impl<(__poison_hash>:: __enable_hash_call &&...), _Types...>; template struct hash> : private __detail::__variant::_Variant_hash_base< variant<_Types...>, std::index_sequence_for<_Types...>>, public __variant_hash_call_base<_Types...> { using result_type [[__deprecated__]] = size_t; using argument_type [[__deprecated__]] = variant<_Types...>; }; template<> struct hash { using result_type [[__deprecated__]] = size_t; using argument_type [[__deprecated__]] = monostate; size_t operator()(const monostate& __t) const noexcept { constexpr size_t __magic_monostate_hash = -7777; return __magic_monostate_hash; } }; template struct __is_fast_hash>> : bool_constant<(__is_fast_hash<_Types>::value && ...)> { }; _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // C++17 #endif // _GLIBCXX_VARIANT