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std:: indirect_result_t

From cppreference.net
C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
indirect_result_t
(C++20)
(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)
헤더 파일에 정의됨 <iterator>
template < class F, class ... Is >

requires ( std:: indirectly_readable < Is > && ... ) &&
std:: invocable < F, std:: iter_reference_t < Is > ... >

using indirect_result_t = std:: invoke_result_t < F, std:: iter_reference_t < Is > ... > ;
(C++20부터)

앨리어스 템플릿 indirect_result_t 는 invocable 타입 F 를 indirectly_readable 타입들 Is... 의 역참조 결과에 적용하여 호출한 결과 타입을 얻습니다.

템플릿 매개변수

F - 호출 가능 타입
Is - 인자로 역참조되는 간접 읽기 가능 타입들

예제

이 코드 실행 
#include <iterator>
#include <type_traits>
struct Fn
{
    long operator()(const int&);
    int operator()(int&&);
    short operator()(int, int) const;
    auto operator()(const float) -> int&;
    void operator()(int[8]);
};
static_assert(
    std::is_same_v<std::indirect_result_t<Fn, const int*>, long> and
    std::is_same_v<std::indirect_result_t<Fn, std::move_iterator<int*>>, int> and
    std::is_same_v<std::indirect_result_t<const Fn, int*, int*>, short> and
    std::is_same_v<std::indirect_result_t<Fn, float*>, int&> and
    std::is_same_v<std::indirect_result_t<Fn, int**>, void>
);
int main() {}

참고 항목

(C++11) (removed in C++20) (C++17)
호출 가능 객체를 인수 집합으로 호출한 결과 타입을 추론함
(클래스 템플릿)
(C++26)
indirectly_readable 타입의 투영을 통해 값 타입을 계산함
(앨리어스 템플릿)