std::readable_traits

 

C++

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Technical Specifications

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
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reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
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empty (C++17)
data (C++17)

 

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.

See also

Readable	specifies that a type is readable by applying operator * (concept)
iter_value_titer_reference_titer_difference_titer_rvalue_reference_titer_common_reference_t	computes the associate types of an iterator (alias template)
iterator_traits	provides uniform interface to the properties of an iterator (class template)