std::experimental::ranges:: Sentinel

The Sentinel concept specifies the relationship between an Iterator type and a Semiregular type whose values denote a range.

Let s and i be values of type S and I , respectively, such that [ i , s ) denotes a range. Sentinel<S, I> is satisfied only if:

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

The domain of == can change over time. Given an iterator i and sentinel s such that [ i , s ) denotes a range and i ! = s , [ i , s ) is not required to continue to denote a range after incrementing any iterator equal to i (and so i == s is no longer required to be well-defined after such an increment).