[iterator.concept.sentinel] (original) (raw)
23 Iterators library [iterators]
23.3 Iterator requirements [iterator.requirements]
23.3.4 Iterator concepts [iterator.concepts]
23.3.4.7 Concept sentinel_for [iterator.concept.sentinel]
The sentinel_for concept specifies the relationship between an input_or_output_iterator type and a semiregular type whose values denote a range.
template<class S, class I> concept sentinel_for = semiregular<S> && input_or_output_iterator<I> && weakly-equality-comparable-with<S, I>; // See [[concept.equalitycomparable]](concept.equalitycomparable)
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
- i == s is well-defined.
- If bool(i != s) then i is dereferenceable and[++i, s) denotes a range.
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.