std::experimental::ranges::iterator_category

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Experimental

Technical Specification

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Extensions for concurrency 2 (concurrency TS v2)

Concepts (concepts TS)

Ranges (ranges TS)

Reflection (reflection TS)

Mathematical special functions (special functions TR)

Experimental Non-TS

Pattern Matching

Linear Algebra

std::execution

Contracts

2D Graphics

 

Ranges

Concepts

General utilities

Iterators

Ranges

Algorithms

 

Iterators library

Iterator concepts
Readable Writable WeaklyIncrementable Incrementable	Iterator Sentinel SizedSentinel	InputIterator ForwardIterator BidirectionalIterator RandomAccessIterator	OutputIterator
Indirect callable concepts
IndirectUnaryInvocableIndirectRegularUnaryInvocable	IndirectUnaryPredicate	IndirectRelation	IndirectStrictWeakOrder
Common algorithm requirements
IndirectlyMovable IndirectlyMovableStorable	IndirectlyCopyable IndirectlyCopyableStorable	IndirectlySwappable IndirectlyComparable	Permutable Mergeable Sortable
Concept utilities
indirect_result_of	projected
Iterator utilities and operations
iter_move iter_swap	advance distance	next prev
Iterator traits
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>
Iterator adaptors
reverse_iterator move_iterator move_sentinel	back_insert_iterator front_insert_iterator insert_iterator	common_iterator counted_iterator default_sentinel	danglingborrowed_iterator_t unreachable
Stream iterators
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)

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)