NAME¶

std::ranges::viewable_range - std::ranges::viewable_range

Synopsis¶

Defined in header <ranges>
template<class T>

concept viewable_range =
ranges::range<T> &&
((ranges::view<std::remove_cvref_t<T>> &&
std::constructible_from<std::remove_cvref_t<T>, T>) || (since C++20)
(!ranges::view<std::remove_cvref_t<T>> &&
(std::is_lvalue_reference_v<T> ||

(std::movable<std::remove_reference_t<T>> &&
!/*is-initializer-list*/<T>))));

The viewable_range concept is a refinement of range that describes a range that can
be safely converted into a view.

The constant /*is-initializer-list*/<T> is true if and only if
std::remove_cvref_t<T> is a specialization of std::initializer_list.

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3481 C++20 viewable_range accepted an lvalue of a rejects
move-only view
P2415R2 C++20 viewable_range only accepted non-view rvalues accepts more types
that are borrowed_range