std::indirect_unary_predicate
From cppreference.com
Defined in header <iterator>
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template< class F, class I > concept indirect_unary_predicate = |
(since C++20) | |
The concept indirect_unary_predicate
specifies requirements for algorithms that call unary predicates as their arguments. The key difference between this concept and std::predicate is that it is applied to the type that I
references, rather than I
itself.
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
P2609R3 | C++20 | one of the requirements was defined in terms of std::iter_value_t<I>& which mishandled projections resulting in incompatibility with predicate F& |
defined in terms of /*indirect-value-t*/<I> to correctly handle such projections |
P2997R1 | C++20 | indirect_unary_predicate required F& to satisfy predicate withstd::iter_common_reference_t<I> |
does not require |