std::experimental::ranges::iterator_category

 

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difference_type value_type reference_trvalue_reference_titer_common_reference_t iterator_category	input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag	ranges::iterator_traits std::iterator_traits<InputIterator>std::iterator_traits<OutputIterator>
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istream_iterator	ostream_iterator	istreambuf_iterator	ostreambuf_iterator

 

Defined in header <experimental/ranges/iterator>
template< class I > struct iterator_category {};	(1)
template< class T > struct iterator_category<T*>;	(2)
template< class T > struct iterator_category<const T> : iterator_category<T> {};	(3)
template< class T >     requires requires { typename T::iterator_category; } struct iterator_category<T>;	(4)

Computes the iterator category of the class I, if any. Users may specialize iterator_category 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 ranges::random_access_iterator_tag. Otherwise, there is no member type.

3) Specialization for const-qualified types.

4) Specialization for types that define a public and accessible member type iterator_category. If T::iterator_category is the same as or derived from one of iterator category tags in namespace std, it is mapped to the corresponding tag in the namespace ranges as described below. Otherwise, provides a member type type equal to T::iterator_category.

• If T::iterator_category is the same as or derives from std::random_access_iterator_tag, provides a member type type equal to ranges::random_access_iterator_tag.
• Otherwise, if T::iterator_category is the same as or derives from std::bidirectional_iterator_tag, provides a member type type equal to ranges::bidirectional_iterator_tag.
• Otherwise, if T::iterator_category is the same as or derives from std::forward_iterator_tag, provides a member type type equal to ranges::forward_iterator_tag.
• Otherwise, if T::iterator_category is the same as or derives from std::input_iterator_tag, provides a member type type equal to ranges::input_iterator_tag.
• Otherwise, if T::iterator_category is the same as or derives from std::output_iterator_tag, there is no member type.

Helper alias template

template< class T > using iterator_category_t = typename ranges::iterator_category<T>::type;		(ranges TS)

Example

See also

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20)	empty class types used to indicate iterator categories (class)
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag	empty class types used to indicate iterator categories (class)
iterator_traits	compatibility traits class that collects an iterator’s associated types (alias template)

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