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Difference between revisions of "cpp/iterator/indirectly unary invocable"

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The concepts {{tt|indirectly_unary_invocable}} and {{tt|indirectly_regular_unary_invocable}} specify requirements for algorithms that call (regular) unary invocables as their arguments. The key difference between these concepts and {{tt|std::invocable}} is that they are applied to the type the {{tt|I}} references, rather than {{tt|I}} itself.
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The concepts {{tt|indirectly_unary_invocable}} and {{tt|indirectly_regular_unary_invocable}} specify requirements for algorithms that call (regular) unary invocables as their arguments. The key difference between these concepts and {{lc|std::invocable}} is that they are applied to the type the {{tt|I}} references, rather than {{tt|I}} itself.
  
 
===Semantic requirements===
 
===Semantic requirements===

Revision as of 00:29, 28 July 2020

 
C++
 
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable
(C++20)(C++20)  
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11)(C++14)
(C++14)(C++14)  
(C++11)(C++14)
(C++14)(C++14)  
(C++17)(C++20)
(C++17)
(C++17)
 
Defined in header <iterator>
template< class F, class I >

concept indirectly_unary_invocable =
  std::indirectly_readable<I> &&
  std::copy_constructible<F> &&
  std::invocable<F&, iter_value_t<I>&> &&
  std::invocable<F&, iter_reference_t<I>> &&
  std::invocable<F&, iter_common_reference_t<I>> &&
  std::common_reference_with<
    std::invoke_result_t<F&, std::iter_value_t<I>&>,

    std::invoke_result_t<F&, std::iter_reference_t<I>>>;
 (since C++20)
template< class F, class I >

  concept indirectly_regular_unary_invocable =
    std::indirectly_readable<I> &&
    std::copy_constructible<F> &&
    std::regular_invocable<F&, iter_value_t<I>&> &&
    std::regular_invocable<F&, iter_reference_t<I>> &&
    std::regular_invocable<F&, iter_common_reference_t<I>> &&
    std::common_reference_with<
      std::invoke_result_t<F&, std::iter_value_t<I>&>,

      std::invoke_result_t<F&, std::iter_reference_t<I>>>;
 (since C++20)

The concepts indirectly_unary_invocable and indirectly_regular_unary_invocable specify requirements for algorithms that call (regular) unary invocables as their arguments. The key difference between these concepts and std::invocable is that they are applied to the type the I references, rather than I itself.

Semantic requirements

Each concept is modeled by F and I only if all concepts it subsume are modeled.

Notes

The distinction between indirectly_unary_invocable and indirectly_regular_unary_invocable is purely semantic.

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