NAME¶

std::experimental::ranges::Predicate - std::experimental::ranges::Predicate

Synopsis¶

Defined in header <experimental/ranges/concepts>
template < class F, class... Args >

concept bool Predicate = (ranges TS)
RegularInvocable<F, Args...> &&

Boolean<std::result_of_t<F&&(Args&&...)>>;

The concept Predicate<F, Args...> specifies that F is a predicate that accepts
arguments whose types and value categories are encoded by Args..., i.e., it can be
invoked with these arguments to produce a Boolean result.

Note that RegularInvocable requires the invocation to not modify either the callable
object or the arguments and be equality-preserving.

Equality preservation

An expression is equality preserving if it results in equal outputs given equal
inputs.

* The inputs to an expression consist of its operands.
* The outputs of an expression consist of its result and all operands modified by
the expression (if any).

Every expression required to be equality preserving is further required to be
stable: two evaluations of such an expression with the same input objects must have
equal outputs absent any explicit intervening modification of those input objects.