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std::experimental::ranges:: iterator_category

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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

This section is incomplete
Reason: no example

See also

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