3.1 KiB
[refwrap.general]
22 General utilities library [utilities]
22.10 Function objects [function.objects]
22.10.6 Class template reference_wrapper [refwrap]
22.10.6.1 General [refwrap.general]
namespace std {template class reference_wrapper {public:// typesusing type = T; // [refwrap.const], constructorstemplateconstexpr reference_wrapper(U&&) noexcept(see below); constexpr reference_wrapper(const reference_wrapper& x) noexcept; // [refwrap.assign], assignmentconstexpr reference_wrapper& operator=(const reference_wrapper& x) noexcept; // [refwrap.access], accessconstexpr operator T& () const noexcept; constexpr T& get() const noexcept; // [refwrap.invoke], invocationtemplate<class... ArgTypes>constexpr invoke_result_t<T&, ArgTypes...> operator()(ArgTypes&&...) constnoexcept(is_nothrow_invocable_v<T&, ArgTypes...>); // [refwrap.comparisons], comparisonsfriend constexpr bool operator==(reference_wrapper, reference_wrapper); friend constexpr bool operator==(reference_wrapper, const T&); friend constexpr bool operator==(reference_wrapper, reference_wrapper); friend constexpr auto operator<=>(reference_wrapper, reference_wrapper); friend constexpr auto operator<=>(reference_wrapper, const T&); friend constexpr auto operator<=>(reference_wrapper, reference_wrapper); }; template reference_wrapper(T&) -> reference_wrapper;}
reference_wrapper is a Cpp17CopyConstructible and Cpp17CopyAssignable wrapper around a reference to an object or function of type T.
reference_wrapper is a trivially copyable type ([basic.types.general]).
The template parameter T of reference_wrapper may be an incomplete type.
[Note 1:
Using the comparison operators described in [refwrap.comparisons] with T being an incomplete type can lead to an ill-formed program with no diagnostic required ([temp.point], [temp.constr.atomic]).
â end note]