NAME¶

std::predicate - std::predicate

Synopsis¶

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

concept predicate = (since C++20)
std::regular_invocable<F, Args...> &&

boolean-testable<std::invoke_result_t<F, Args...>>;

The concept std::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-testable result.

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

Equality preservation

Expressions declared in requires expressions of the standard library concepts are
required to be equality-preserving (except where stated otherwise).