20 General utilities library [utilities]

20.15 Metaprogramming and type traits [meta]

20.15.3 Header <type_­traits> synopsis [meta.type.synop]

namespace std { // [meta.help], helper class template<class T, T v> struct integral_constant; template<bool B> using bool_constant = integral_constant<bool, B>; using true_type = bool_constant<true>; using false_type = bool_constant<false>; // [meta.unary.cat], primary type categories template<class T> struct is_void; template<class T> struct is_null_pointer; template<class T> struct is_integral; template<class T> struct is_floating_point; template<class T> struct is_array; template<class T> struct is_pointer; template<class T> struct is_lvalue_reference; template<class T> struct is_rvalue_reference; template<class T> struct is_member_object_pointer; template<class T> struct is_member_function_pointer; template<class T> struct is_enum; template<class T> struct is_union; template<class T> struct is_class; template<class T> struct is_function; // [meta.unary.comp], composite type categories template<class T> struct is_reference; template<class T> struct is_arithmetic; template<class T> struct is_fundamental; template<class T> struct is_object; template<class T> struct is_scalar; template<class T> struct is_compound; template<class T> struct is_member_pointer; // [meta.unary.prop], type properties template<class T> struct is_const; template<class T> struct is_volatile; template<class T> struct is_trivial; template<class T> struct is_trivially_copyable; template<class T> struct is_standard_layout; template<class T> struct is_empty; template<class T> struct is_polymorphic; template<class T> struct is_abstract; template<class T> struct is_final; template<class T> struct is_aggregate; template<class T> struct is_signed; template<class T> struct is_unsigned; template<class T> struct is_bounded_array; template<class T> struct is_unbounded_array; template<class T> struct is_scoped_enum; template<class T, class... Args> struct is_constructible; template<class T> struct is_default_constructible; template<class T> struct is_copy_constructible; template<class T> struct is_move_constructible; template<class T, class U> struct is_assignable; template<class T> struct is_copy_assignable; template<class T> struct is_move_assignable; template<class T, class U> struct is_swappable_with; template<class T> struct is_swappable; template<class T> struct is_destructible; template<class T, class... Args> struct is_trivially_constructible; template<class T> struct is_trivially_default_constructible; template<class T> struct is_trivially_copy_constructible; template<class T> struct is_trivially_move_constructible; template<class T, class U> struct is_trivially_assignable; template<class T> struct is_trivially_copy_assignable; template<class T> struct is_trivially_move_assignable; template<class T> struct is_trivially_destructible; template<class T, class... Args> struct is_nothrow_constructible; template<class T> struct is_nothrow_default_constructible; template<class T> struct is_nothrow_copy_constructible; template<class T> struct is_nothrow_move_constructible; template<class T, class U> struct is_nothrow_assignable; template<class T> struct is_nothrow_copy_assignable; template<class T> struct is_nothrow_move_assignable; template<class T, class U> struct is_nothrow_swappable_with; template<class T> struct is_nothrow_swappable; template<class T> struct is_nothrow_destructible; template<class T> struct has_virtual_destructor; template<class T> struct has_unique_object_representations; // [meta.unary.prop.query], type property queries template<class T> struct alignment_of; template<class T> struct rank; template<class T, unsigned I = 0> struct extent; // [meta.rel], type relations template<class T, class U> struct is_same; template<class Base, class Derived> struct is_base_of; template<class From, class To> struct is_convertible; template<class From, class To> struct is_nothrow_convertible; template<class T, class U> struct is_layout_compatible; template<class Base, class Derived> struct is_pointer_interconvertible_base_of; template<class Fn, class... ArgTypes> struct is_invocable; template<class R, class Fn, class... ArgTypes> struct is_invocable_r; template<class Fn, class... ArgTypes> struct is_nothrow_invocable; template<class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r; // [meta.trans.cv], const-volatile modifications template<class T> struct remove_const; template<class T> struct remove_volatile; template<class T> struct remove_cv; template<class T> struct add_const; template<class T> struct add_volatile; template<class T> struct add_cv; template<class T> using remove_const_t = typename remove_­const<T>::type; template<class T> using remove_volatile_t = typename remove_­volatile<T>::type; template<class T> using remove_cv_t = typename remove_­cv<T>::type; template<class T> using add_const_t = typename add_­const<T>::type; template<class T> using add_volatile_t = typename add_­volatile<T>::type; template<class T> using add_cv_t = typename add_­cv<T>::type; // [meta.trans.ref], reference modifications template<class T> struct remove_reference; template<class T> struct add_lvalue_reference; template<class T> struct add_rvalue_reference; template<class T> using remove_reference_t = typename remove_­reference<T>::type; template<class T> using add_lvalue_reference_t = typename add_­lvalue_­reference<T>::type; template<class T> using add_rvalue_reference_t = typename add_­rvalue_­reference<T>::type; // [meta.trans.sign], sign modifications template<class T> struct make_signed; template<class T> struct make_unsigned; template<class T> using make_signed_t = typename make_­signed<T>::type; template<class T> using make_unsigned_t = typename make_­unsigned<T>::type; // [meta.trans.arr], array modifications template<class T> struct remove_extent; template<class T> struct remove_all_extents; template<class T> using remove_extent_t = typename remove_­extent<T>::type; template<class T> using remove_all_extents_t = typename remove_­all_­extents<T>::type; // [meta.trans.ptr], pointer modifications template<class T> struct remove_pointer; template<class T> struct add_pointer; template<class T> using remove_pointer_t = typename remove_­pointer<T>::type; template<class T> using add_pointer_t = typename add_­pointer<T>::type; // [meta.trans.other], other transformations template<class T> struct type_identity; template<size_t Len, size_t Align = default-alignment> // see [meta.trans.other] struct aligned_storage; template<size_t Len, class... Types> struct aligned_union; template<class T> struct remove_cvref; template<class T> struct decay; template<bool, class T = void> struct enable_if; template<bool, class T, class F> struct conditional; template<class... T> struct common_type; template<class T, class U, template<class> class TQual, template<class> class UQual> struct basic_common_reference { }; template<class... T> struct common_reference; template<class T> struct underlying_type; template<class Fn, class... ArgTypes> struct invoke_result; template<class T> struct unwrap_reference; template<class T> struct unwrap_ref_decay; template<class T> using type_identity_t = typename type_­identity<T>::type; template<size_t Len, size_t Align = default-alignment> // see [meta.trans.other] using aligned_storage_t = typename aligned_­storage<Len, Align>::type; template<size_t Len, class... Types> using aligned_union_t = typename aligned_­union<Len, Types...>::type; template<class T> using remove_cvref_t = typename remove_­cvref<T>::type; template<class T> using decay_t = typename decay<T>::type; template<bool b, class T = void> using enable_if_t = typename enable_­if<b, T>::type; template<bool b, class T, class F> using conditional_t = typename conditional<b, T, F>::type; template<class... T> using common_type_t = typename common_­type<T...>::type; template<class... T> using common_reference_t = typename common_­reference<T...>::type; template<class T> using underlying_type_t = typename underlying_­type<T>::type; template<class Fn, class... ArgTypes> using invoke_result_t = typename invoke_­result<Fn, ArgTypes...>::type; template<class T> using unwrap_reference_t = typename unwrap_­reference<T>::type; template<class T> using unwrap_ref_decay_t = typename unwrap_­ref_­decay<T>::type; template<class...> using void_t = void; // [meta.logical], logical operator traits template<class... B> struct conjunction; template<class... B> struct disjunction; template<class B> struct negation; // [meta.unary.cat], primary type categories template<class T> inline constexpr bool is_void_v = is_­void<T>::value; template<class T> inline constexpr bool is_null_pointer_v = is_­null_­pointer<T>::value; template<class T> inline constexpr bool is_integral_v = is_­integral<T>::value; template<class T> inline constexpr bool is_floating_point_v = is_­floating_­point<T>::value; template<class T> inline constexpr bool is_array_v = is_­array<T>::value; template<class T> inline constexpr bool is_pointer_v = is_­pointer<T>::value; template<class T> inline constexpr bool is_lvalue_reference_v = is_­lvalue_­reference<T>::value; template<class T> inline constexpr bool is_rvalue_reference_v = is_­rvalue_­reference<T>::value; template<class T> inline constexpr bool is_member_object_pointer_v = is_­member_­object_­pointer<T>::value; template<class T> inline constexpr bool is_member_function_pointer_v = is_­member_­function_­pointer<T>::value; template<class T> inline constexpr bool is_enum_v = is_­enum<T>::value; template<class T> inline constexpr bool is_union_v = is_­union<T>::value; template<class T> inline constexpr bool is_class_v = is_­class<T>::value; template<class T> inline constexpr bool is_function_v = is_­function<T>::value; // [meta.unary.comp], composite type categories template<class T> inline constexpr bool is_reference_v = is_­reference<T>::value; template<class T> inline constexpr bool is_arithmetic_v = is_­arithmetic<T>::value; template<class T> inline constexpr bool is_fundamental_v = is_­fundamental<T>::value; template<class T> inline constexpr bool is_object_v = is_­object<T>::value; template<class T> inline constexpr bool is_scalar_v = is_­scalar<T>::value; template<class T> inline constexpr bool is_compound_v = is_­compound<T>::value; template<class T> inline constexpr bool is_member_pointer_v = is_­member_­pointer<T>::value; // [meta.unary.prop], type properties template<class T> inline constexpr bool is_const_v = is_­const<T>::value; template<class T> inline constexpr bool is_volatile_v = is_­volatile<T>::value; template<class T> inline constexpr bool is_trivial_v = is_­trivial<T>::value; template<class T> inline constexpr bool is_trivially_copyable_v = is_­trivially_­copyable<T>::value; template<class T> inline constexpr bool is_standard_layout_v = is_­standard_­layout<T>::value; template<class T> inline constexpr bool is_empty_v = is_empty<T>::value; template<class T> inline constexpr bool is_polymorphic_v = is_­polymorphic<T>::value; template<class T> inline constexpr bool is_abstract_v = is_­abstract<T>::value; template<class T> inline constexpr bool is_final_v = is_­final<T>::value; template<class T> inline constexpr bool is_aggregate_v = is_­aggregate<T>::value; template<class T> inline constexpr bool is_signed_v = is_signed<T>::value; template<class T> inline constexpr bool is_unsigned_v = is_­unsigned<T>::value; template<class T> inline constexpr bool is_bounded_array_v = is_­bounded_­array<T>::value; template<class T> inline constexpr bool is_unbounded_array_v = is_unbounded_array<T>::value; template<class T> inline constexpr bool is_scoped_enum_v = is_scoped_enum<T>::value; template<class T, class... Args> inline constexpr bool is_constructible_v = is_­constructible<T, Args...>::value; template<class T> inline constexpr bool is_default_constructible_v = is_­default_­constructible<T>::value; template<class T> inline constexpr bool is_copy_constructible_v = is_­copy_­constructible<T>::value; template<class T> inline constexpr bool is_move_constructible_v = is_­move_­constructible<T>::value; template<class T, class U> inline constexpr bool is_assignable_v = is_­assignable<T, U>::value; template<class T> inline constexpr bool is_copy_assignable_v = is_­copy_­assignable<T>::value; template<class T> inline constexpr bool is_move_assignable_v = is_­move_­assignable<T>::value; template<class T, class U> inline constexpr bool is_swappable_with_v = is_­swappable_­with<T, U>::value; template<class T> inline constexpr bool is_swappable_v = is_­swappable<T>::value; template<class T> inline constexpr bool is_destructible_v = is_­destructible<T>::value; template<class T, class... Args> inline constexpr bool is_trivially_constructible_v = is_­trivially_­constructible<T, Args...>::value; template<class T> inline constexpr bool is_trivially_default_constructible_v = is_­trivially_­default_­constructible<T>::value; template<class T> inline constexpr bool is_trivially_copy_constructible_v = is_­trivially_­copy_­constructible<T>::value; template<class T> inline constexpr bool is_trivially_move_constructible_v = is_­trivially_­move_­constructible<T>::value; template<class T, class U> inline constexpr bool is_trivially_assignable_v = is_­trivially_­assignable<T, U>::value; template<class T> inline constexpr bool is_trivially_copy_assignable_v = is_­trivially_­copy_­assignable<T>::value; template<class T> inline constexpr bool is_trivially_move_assignable_v = is_­trivially_­move_­assignable<T>::value; template<class T> inline constexpr bool is_trivially_destructible_v = is_­trivially_­destructible<T>::value; template<class T, class... Args> inline constexpr bool is_nothrow_constructible_v = is_­nothrow_­constructible<T, Args...>::value; template<class T> inline constexpr bool is_nothrow_default_constructible_v = is_­nothrow_­default_­constructible<T>::value; template<class T> inline constexpr bool is_nothrow_copy_constructible_v = is_­nothrow_­copy_­constructible<T>::value; template<class T> inline constexpr bool is_nothrow_move_constructible_v = is_­nothrow_­move_­constructible<T>::value; template<class T, class U> inline constexpr bool is_nothrow_assignable_v = is_­nothrow_­assignable<T, U>::value; template<class T> inline constexpr bool is_nothrow_copy_assignable_v = is_­nothrow_­copy_­assignable<T>::value; template<class T> inline constexpr bool is_nothrow_move_assignable_v = is_­nothrow_­move_­assignable<T>::value; template<class T, class U> inline constexpr bool is_nothrow_swappable_with_v = is_­nothrow_­swappable_­with<T, U>::value; template<class T> inline constexpr bool is_nothrow_swappable_v = is_­nothrow_­swappable<T>::value; template<class T> inline constexpr bool is_nothrow_destructible_v = is_­nothrow_­destructible<T>::value; template<class T> inline constexpr bool has_virtual_destructor_v = has_­virtual_­destructor<T>::value; template<class T> inline constexpr bool has_unique_object_representations_v = has_­unique_­object_­representations<T>::value; // [meta.unary.prop.query], type property queries template<class T> inline constexpr size_t alignment_of_v = alignment_­of<T>::value; template<class T> inline constexpr size_t rank_v = rank<T>::value; template<class T, unsigned I = 0> inline constexpr size_t extent_v = extent<T, I>::value; // [meta.rel], type relations template<class T, class U> inline constexpr bool is_same_v = is_­same<T, U>::value; template<class Base, class Derived> inline constexpr bool is_base_of_v = is_­base_­of<Base, Derived>::value; template<class From, class To> inline constexpr bool is_convertible_v = is_­convertible<From, To>::value; template<class From, class To> inline constexpr bool is_nothrow_convertible_v = is_­nothrow_­convertible<From, To>::value; template<class T, class U> inline constexpr bool is_layout_compatible_v = is_­layout_­compatible<T, U>::value; template<class Base, class Derived> inline constexpr bool is_pointer_interconvertible_base_of_v = is_­pointer_­interconvertible_­base_­of<Base, Derived>::value; template<class Fn, class... ArgTypes> inline constexpr bool is_invocable_v = is_­invocable<Fn, ArgTypes...>::value; template<class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v = is_­invocable_­r<R, Fn, ArgTypes...>::value; template<class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v = is_­nothrow_­invocable<Fn, ArgTypes...>::value; template<class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v = is_­nothrow_­invocable_­r<R, Fn, ArgTypes...>::value; // [meta.logical], logical operator traits template<class... B> inline constexpr bool conjunction_v = conjunction<B...>::value; template<class... B> inline constexpr bool disjunction_v = disjunction<B...>::value; template<class B> inline constexpr bool negation_v = negation<B>::value; // [meta.member], member relationships template<class S, class M> constexpr bool is_pointer_interconvertible_with_class(M S::*m) noexcept; template<class S1, class S2, class M1, class M2> constexpr bool is_corresponding_member(M1 S1::*m1, M2 S2::*m2) noexcept; // [meta.const.eval], constant evaluation context constexpr bool is_constant_evaluated() noexcept; }