cppdraft_translate/cppdraft/iterator/concepts/general.md

[iterator.concepts.general]

24 Iterators library [iterators]

24.3 Iterator requirements [iterator.requirements]

24.3.4 Iterator concepts [iterator.concepts]

24.3.4.1 General [iterator.concepts.general]

1

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For a type I, let ITER_TRAITS(I) denote the type I if iterator_traits names a specialization generated from the primary template.

Otherwise, ITER_TRAITS(I) denotesiterator_traits.

• (1.1)

  If the qualified-idITER_TRAITS(I)​::​iterator_concept is valid and names a type, then ITER_CONCEPT(I) denotes that type.

• (1.2)

  Otherwise, if the qualified-idITER_TRAITS(I)​​::​iterator_category is valid and names a type, then ITER_CONCEPT(I) denotes that type.

• (1.3)

  Otherwise, if iterator_traits names a specialization generated from the primary template, then ITER_CONCEPT(I) denotes random_access_iterator_tag.

• (1.4)

  Otherwise, ITER_CONCEPT(I) does not denote a type.

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[Note 1:

ITER_TRAITS enables independent syntactic determination of an iterator's category and concept.

— end note]

[Example 1:

struct I {using value_type = int; using difference_type = int; int operator*() const; I& operator++(); I operator++(int); I& operator--(); I operator--(int); bool operator==(I) const;};iterator_traits​::​iterator_category denotes input_iterator_tag, and ITER_CONCEPT(I) denotes random_access_iterator_tag.

— end example]