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std::indirect_binary_predicate

Defined in header <iterator>
template< class F, class I1, class I2 >
concept indirect_binary_predicate =
  std::indirectly_readable<I1> &&
  std::indirectly_readable<I2> &&
  std::copy_constructible<F> &&
  std::predicate<F&, std::iter_value_t<I1>&, std::iter_value_t<I2>&> &&
  std::predicate<F&, std::iter_value_t<I1>&, std::iter_reference_t<I2>> &&
  std::predicate<F&, std::iter_reference_t<I1>, std::iter_value_t<I2>&> &&
  std::predicate<F&, std::iter_reference_t<I1>, std::iter_reference_t<I2>> &&
  std::predicate<F&, std::iter_common_reference_t<I1>, std::iter_common_reference_t<I2>>;
(since C++20)

The concept indirect_binary_predicate specifies requirements for algorithms that call binary predicates as their arguments. The key difference between this concept and std::predicate is that it is applied to the types that I1 and I2 references, rather than I1 and I2 themselves.

Semantic requirements

F, I1, and I2 model indirect_binary_predicate only if all concepts it subsumes are modeled.

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