cpp/ranges/basic istream view

@1@ A range factory that generates a sequence of elements by repeatedly calling.

@2-3@ Convenience alias templates for character types and.

@4@ is expression-equivalent to (has the same effect as)  for any suitable subexpressions, where  is. The program is ill-formed if is not both publicly and unambiguously derived from, which may result in a substitution failure.

@5@ The exposition-only concept is satisfied when lvalue of  can be extracted from lvalue of.

The iterator type of is move-only: it does not meet the  requirements, and thus does not work with pre-C++20 algorithms.