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std::indirect_unary_predicate

From cppreference.com
< cpp‎ | iterator
 
 
Iterator library
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Indirect callable concepts
indirect_unary_predicate
(C++20)
Common algorithm requirements
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(C++11)
(C++11)
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(C++11)(C++14)
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(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
Defined in header <iterator>
template<class F, class I>

concept indirect_unary_predicate =
  std::indirectly_readable<I> &&
  std::copy_constructible<F> &&
  std::predicate<F&, std::iter_value_t<I>&> &&
  std::predicate<F&, std::iter_reference_t<I>> &&

  std::predicate<F&, std::iter_common_reference_t<I>>;
(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.

[edit] Semantic requirements

F and I model indirect_unary_predicate only if all concepts it subsumes are modeled.