std::readable_traits
Defined in header <iterator> | ||
|---|---|---|
template< class I >
struct readable_traits { };
| (1) | (since C++20) |
template< class T > struct readable_traits<T*>; | (2) | (since C++20) |
template< class I > requires std::is_array_v<I> struct readable_traits<I>; | (3) | (since C++20) |
template< class T >
struct readable_traits<const T> : value_type<T> { };
| (4) | (since C++20) |
template <class T>
requires requires { typename T::value_type; }
struct readable_traits<T>;
| (5) | (since C++20) |
template <class T>
requires requires { typename T::element_type; }
struct readable_traits<T>;
| (6) | (since C++20) |
Computes the associated value type of the type I, if any. Users may specialize readable_traits 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 value_type equal to std::remove_cv_t<T>. Otherwise, there is no member value_type.
3) Specialization for array types. Provides a member type
value_type equal to std::remove_cv_t<std::remove_extent_t<I>>.
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 value_type equal to std::remove_cv_t<typename T::value_type>. Otherwise, there is no member value_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 value_type equal to std::remove_cv_t<typename T::element_type>. Otherwise, there is no member value_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
See also
specifies that a type is readable by applying operator * (concept) |
|
| computes the associate types of an iterator (alias template) |
|
| provides uniform interface to the properties of an iterator (class template) |
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