std::predicate
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predicate
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Exposition-only concepts
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Defined in header
<concepts>
template< class F, class... Args >
(since C++20)
concept predicate =
std::regular_invocable <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.
[edit] Equality preservation
Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 18.7.4 Concept
predicate[concept.predicate]
- 18.7.4 Concept
- C++20 standard (ISO/IEC 14882:2020):
- 18.7.4 Concept
predicate[concept.predicate]
- 18.7.4 Concept