std::experimental::ranges::Relation (3) Linux Manual Page

std::experimental::ranges::Relation – std::experimental::ranges::Relation

Synopsis

Defined in header<experimental / ranges / concepts>

    template <class R, class T, class U>

    concept bool Relation =

        Predicate<R, T, T> &&

        Predicate<R, U, U> &&

        CommonReference<

            const std::remove_reference_t<T> &,

            const std::remove_reference_t<U> &> &&

        Predicate<R, (1)(ranges TS)

                         ranges::common_reference_t<

                             const std::remove_reference_t<T> &,

                             const std::remove_reference_t<U> &>,

                  ranges::common_reference_t<

                      const std::remove_reference_t<T> &,

                      const std::remove_reference_t<U> &>> &&

        Predicate<R, T, U> &&

        Predicate<R, U, T>;

The concept Relation<R, T, U> specifies that R defines a binary relation over the set of expressions whose type and value category are those encoded by either T or U.
Given
* r, an expression such that decltype((r)) is R,
* t, an expression such that decltype((t)) is T,
* u, an expression such that decltype((u)) is U,
and let C be ranges::common_reference_t<const std::remove_reference_t<T>&, const std::remove_reference_t<U>&>,
then Relation<R, T, U> is satisfied only if
* bool(r(t, u)) == bool(r(C(t), C(u))) and
* bool(r(u, t)) == bool(r(C(u), C(t))).