diff options
Diffstat (limited to 'include/variant')
| -rw-r--r-- | include/variant | 46 |
1 files changed, 38 insertions, 8 deletions
diff --git a/include/variant b/include/variant index f8d3e28bae45..8a66add865ae 100644 --- a/include/variant +++ b/include/variant @@ -207,11 +207,15 @@ namespace std { #include <tuple> #include <type_traits> #include <utility> +#include <limits> #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) #pragma GCC system_header #endif +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + namespace std { // explicitly not using versioning namespace class _LIBCPP_EXCEPTION_ABI bad_variant_access : public exception { @@ -283,7 +287,28 @@ struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { }; constexpr size_t variant_npos = static_cast<size_t>(-1); -constexpr unsigned int __variant_npos = static_cast<unsigned int>(-1); + +constexpr int __choose_index_type(unsigned int __num_elem) { + if (__num_elem < std::numeric_limits<unsigned char>::max()) + return 0; + if (__num_elem < std::numeric_limits<unsigned short>::max()) + return 1; + return 2; +} + +template <size_t _NumAlts> +using __variant_index_t = +#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION + unsigned int; +#else + std::tuple_element_t< + __choose_index_type(_NumAlts), + std::tuple<unsigned char, unsigned short, unsigned int> + >; +#endif + +template <class _IndexType> +constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); namespace __find_detail { @@ -557,7 +582,7 @@ struct __variant { private: template <class _Visitor, class... _Values> static constexpr void __std_visit_exhaustive_visitor_check() { - static_assert(is_callable_v<_Visitor(_Values...)>, + static_assert(is_invocable_v<_Visitor, _Values...>, "`std::visit` requires the visitor to be exhaustive."); } @@ -647,9 +672,11 @@ _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); template <_Trait _DestructibleTrait, class... _Types> class _LIBCPP_TEMPLATE_VIS __base { public: + using __index_t = __variant_index_t<sizeof...(_Types)>; + inline _LIBCPP_INLINE_VISIBILITY explicit constexpr __base(__valueless_t tag) noexcept - : __data(tag), __index(__variant_npos) {} + : __data(tag), __index(__variant_npos<__index_t>) {} template <size_t _Ip, class... _Args> inline _LIBCPP_INLINE_VISIBILITY @@ -665,7 +692,7 @@ public: inline _LIBCPP_INLINE_VISIBILITY constexpr size_t index() const noexcept { - return __index == __variant_npos ? variant_npos : __index; + return __index == __variant_npos<__index_t> ? variant_npos : __index; } protected: @@ -685,7 +712,7 @@ protected: static constexpr size_t __size() { return sizeof...(_Types); } __union<_DestructibleTrait, 0, _Types...> __data; - unsigned int __index; + __index_t __index; friend struct __access::__base; friend struct __visitation::__base; @@ -696,10 +723,11 @@ class _LIBCPP_TEMPLATE_VIS __destructor; #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ template <class... _Types> \ - class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \ + class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \ destructible_trait> \ : public __base<destructible_trait, _Types...> { \ using __base_type = __base<destructible_trait, _Types...>; \ + using __index_t = typename __base_type::__index_t; \ \ public: \ using __base_type::__base_type; \ @@ -719,7 +747,7 @@ class _LIBCPP_TEMPLATE_VIS __destructor; _LIBCPP_VARIANT_DESTRUCTOR( _Trait::_TriviallyAvailable, ~__destructor() = default;, - void __destroy() noexcept { this->__index = __variant_npos; }); + void __destroy() noexcept { this->__index = __variant_npos<__index_t>; }); _LIBCPP_VARIANT_DESTRUCTOR( _Trait::_Available, @@ -733,7 +761,7 @@ _LIBCPP_VARIANT_DESTRUCTOR( }, *this); } - this->__index = __variant_npos; + this->__index = __variant_npos<__index_t>; }); _LIBCPP_VARIANT_DESTRUCTOR( @@ -1561,4 +1589,6 @@ struct _LIBCPP_TEMPLATE_VIS hash<monostate> { _LIBCPP_END_NAMESPACE_STD +_LIBCPP_POP_MACROS + #endif // _LIBCPP_VARIANT |