This component‐private metafunction computes an overload set consisting of one function, named candidate, for each type in (template parameters) t_HEAD, t_TAIL..., having one parameter of that type. Each such function participates in overload resolution only when std::declval<t_SRC>() is convertible to the alternative without narrowing, and returns bsl::integral_constant<t_INDEX + i>, where i is the zero‐based index of the corresponding alternative. Note that a type that occurs multiple times in t_HEAD, t_TAIL... (possibly with varying cv‐qualifications) will only result in the generation of a single candidate. This implementation relies on expression SFINAE, decltype, std::declval, and P1957R2; since these features are not available in C++03, the C++03 version requires an exact match modulo cv‐qualification.

Synopsis

Declared in <bslstl_variant.h>

template<
    class t_SRC,
    size_t t_INDEX,
    class t_HEAD,
    class... t_TAIL>
struct Variant_OverloadSetImp
    : Variant_OverloadSetImp<t_SRC, t_INDEX + 1, t_TAIL...>

Base Classes

Name

Description

Variant_OverloadSetImp<t_SRC, t_INDEX + 1, t_TAIL...>

This component‐private metafunction computes an overload set consisting of one function, named candidate, for each type in (template parameters) t_HEAD, t_TAIL..., having one parameter of that type. Each such function participates in overload resolution only when std::declval<t_SRC>() is convertible to the alternative without narrowing, and returns bsl::integral_constant<t_INDEX + i>, where i is the zero‐based index of the corresponding alternative. Note that a type that occurs multiple times in t_HEAD, t_TAIL... (possibly with varying cv‐qualifications) will only result in the generation of a single candidate. This implementation relies on expression SFINAE, decltype, std::declval, and P1957R2; since these features are not available in C++03, the C++03 version requires an exact match modulo cv‐qualification.

Static Member Functions

Name

Description

candidate

Overload candidate selecting alternative t_INDEX for source type t_SRC.

Using Declarations

Name

candidate

Specializations

Name

Variant_OverloadSetImp<t_SRC, t_INDEX, t_HEAD>

Derived Classes

Name

Description

Variant_OverloadSetImp

This component‐private metafunction computes an overload set consisting of one function, named candidate, for each type in (template parameters) t_HEAD, t_TAIL..., having one parameter of that type. Each such function participates in overload resolution only when std::declval<t_SRC>() is convertible to the alternative without narrowing, and returns bsl::integral_constant<t_INDEX + i>, where i is the zero‐based index of the corresponding alternative. Note that a type that occurs multiple times in t_HEAD, t_TAIL... (possibly with varying cv‐qualifications) will only result in the generation of a single candidate. This implementation relies on expression SFINAE, decltype, std::declval, and P1957R2; since these features are not available in C++03, the C++03 version requires an exact match modulo cv‐qualification.

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