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cppdraft/iterator/concepts/general.md

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+[iterator.concepts.general]
+
+# 24 Iterators library [[iterators]](./#iterators)
+
+## 24.3 Iterator requirements [[iterator.requirements]](iterator.requirements#iterator.concepts.general)
+
+### 24.3.4 Iterator concepts [[iterator.concepts]](iterator.concepts#general)
+
+#### 24.3.4.1 General [iterator.concepts.general]
+
+[1](#1)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L1252)
+
+For a type I, let *ITER_TRAITS*(I) denote
+the type I if iterator_traits<I> names
+a specialization generated from the primary template[.](#1.sentence-1)
+
+Otherwise, *ITER_TRAITS*(I) denotesiterator_traits<I>[.](#1.sentence-2)
+
+- [(1.1)](#1.1)
+
+  If the [*qualified-id*](expr.prim.id.qual#nt:qualified-id "7.5.5.3 Qualified names [expr.prim.id.qual]")*ITER_TRAITS*(I)​::​iterator_concept is valid
+ and names a type, then *ITER_CONCEPT*(I) denotes that
+ type[.](#1.1.sentence-1)
+
+- [(1.2)](#1.2)
+
+  Otherwise, if the [*qualified-id*](expr.prim.id.qual#nt:qualified-id "7.5.5.3 Qualified names [expr.prim.id.qual]")*ITER_TRAITS*(I)​​::​iterator_category is valid and names a type, then *ITER_CONCEPT*(I) denotes that type[.](#1.2.sentence-1)
+
+- [(1.3)](#1.3)
+
+  Otherwise, if iterator_traits<I> names a specialization generated
+ from the primary template, then *ITER_CONCEPT*(I) denotes random_access_iterator_tag[.](#1.3.sentence-1)
+
+- [(1.4)](#1.4)
+
+  Otherwise, *ITER_CONCEPT*(I) does not denote a type[.](#1.4.sentence-1)
+
+[2](#2)
+
+[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L1273)
+
+[*Note [1](#note-1)*:
+
+*ITER_TRAITS* enables independent syntactic determination
+of an iterator's category and concept[.](#2.sentence-1)
+
+— *end note*]
+
+[*Example [1](#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<I>​::​iterator_category denotes input_iterator_tag,
+and *ITER_CONCEPT*(I) denotes random_access_iterator_tag[.](#2.sentence-2)
+
+— *end example*]