table of contents
std::projected(3) | C++ Standard Libary | std::projected(3) |
NAME¶
std::projected - std::projected
Synopsis¶
Defined in header <iterator>
template< std::indirectly_readable I,
std::indirectly_regular_unary_invocable<I> Proj >
struct projected { (since
using value_type =
std::remove_cvref_t<std::indirect_result_t<Proj&, (1)
C++20)
I>>;
std::indirect_result_t<Proj&, I> operator*() const; // not
defined
};
template< std::weakly_incrementable I, class Proj >
struct incrementable_traits<std::projected<I, Proj>> { (2)
(since
using difference_type = std::iter_difference_t<I>; C++20)
};
1) Class template projected combines an indirectly_readable type I and a
callable
object type Proj into a new indirectly_readable type whose reference type is
the
result of applying Proj to the std::iter_reference_t<I>.
2) This specialization of std::incrementable_traits makes
std::projected<I, Proj> a
weakly_incrementable type when I is also a weakly_incrementable type.
projected is used only to constrain algorithms that accept callable objects
and
projections, and hence its operator*() is not defined.
Template parameters¶
I - an indirectly readable type
Proj - projection applied to a dereferenced I
2022.07.31 | http://cppreference.com |