std::experimental::ranges::value_type (3) Linux Manual Page

std::experimental::ranges::value_type – std::experimental::ranges::value_type

Synopsis

Defined in header<experimental / ranges / iterator>

    template <class I>
    (1)

        struct value_type {
};

template <class T>
(2)

    struct value_type<T *>;

template <class I>

requires std::is_array<I>::value(3)

struct value_type<I> : value_type<std::decay_t<I>> {
};

template <class T>
(4)

    struct value_type<const T> : value_type<std::decay_t<T>> {
};

template <class T>

requires requires
{
    typename T::value_type;
}
(5)

    struct value_type<T>;

template <class T>

requires requires
{
    typename T::element_type;
}
(6)

    struct value_type<T>;

Computes the associated value type of the type I, if any. Users may specialize value_type for a program-defined type.
1) Primary template is an empty struct.
2) Specialization for pointers. If T is an object type, provides a member type type equal to std::remove_cv_t<T>. Otherwise, there is no member type.
3) Specialization for array types.
4) Specialization for const-qualified types.
5) Specialization for types that define a public and accessible member type value_type. If T::value_type is an object type, provides a member type type equal to T::value_type. Otherwise, there is no member type.
6) Specialization for types that define a public and accessible member type element_type (e.g., std::shared_ptr). If T::element_type is an object type, provides a member type type equal to std::remove_cv_t<typename T::element_type>. Otherwise, there is no member type.
Helper alias template

template< class T >                                         (ranges TS)

using value_type_t = typename ranges::value_type<T>::type;

Notes

If a type contains both a value_type member and a element_type member, then the specializations (5) and (6) are ambiguous.
value_type is intended for use with Readable types such as iterators. It is not intended for use with ranges.

Example

 This section is incomplete
 Reason: no example

See also

                specifies that a type is readable by applying operator *
Readable (concept)
                compatibility traits class that collects an iterator’s associated types
iterator_traits (alias template)