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std::experimental::ranges::Relation

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< cpp‎ | experimental‎ | ranges
 
 
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URNG concept
 
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,
        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>;
(1) (ranges TS)

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))).