cppdraft_translate/cppdraft/iterator/concept/sentinel.md

[iterator.concept.sentinel]

24 Iterators library [iterators]

24.3 Iterator requirements [iterator.requirements]

24.3.4 Iterator concepts [iterator.concepts]

24.3.4.7 Concept sentinel_for [iterator.concept.sentinel]

1

#

The sentinel_for concept specifies the relationship between an input_or_output_iterator type and a semiregular type whose values denote a range.

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template<class S, class I> concept [sentinel_for](#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]") = [semiregular](concepts.object#concept:semiregular "18.6 Object concepts [concepts.object]")<S> && [input_or_output_iterator](iterator.concept.iterator#concept:input_or_output_iterator "24.3.4.6 Concept input_­or_­output_­iterator [iterator.concept.iterator]")<I> && [weakly-equality-comparable-with](concept.equalitycomparable#concept:weakly-equality-comparable-with "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<S, I>; // see [[concept.equalitycomparable]](concept.equalitycomparable "18.5.4 Concept equality_­comparable")

2

#

Let s and i be values of type S andI such that [i, s) denotes a range.

TypesS and I model sentinel_for<S, I> only if:

• (2.1)

  i == s is well-defined.

• (2.2)

  If bool(i != s) then i is dereferenceable and [++i, s) denotes a range.

• (2.3)

  assignable_from<I&, S> is either modeled or not satisfied.

3

#

The domain of == is not static.

Given an iterator i and sentinel s such that [i, s) denotes a range and i != s, i and s are not required to continue to denote a range after incrementing any other iterator equal to i.

Consequently, i == s is no longer required to be well-defined.