Difference between revisions of "cpp/iterator/projected"
From cppreference.com
m |
m (fmt) |
||
| Line 23: | Line 23: | ||
@2@ This specialization of {{lc|std::incrementable_traits}} makes {{c|std::projected<I, Proj>}} a {{lconcept|weakly_incrementable}} type when {{tt|I}} is also a {{tt|weakly_incrementable}} type. | @2@ This specialization of {{lc|std::incrementable_traits}} makes {{c|std::projected<I, Proj>}} a {{lconcept|weakly_incrementable}} type when {{tt|I}} is also a {{tt|weakly_incrementable}} type. | ||
| − | {{tt|projected}} is only used to constrain algorithms that accept callable objects and projections, and hence its {{ | + | {{tt|projected}} is only used to constrain algorithms that accept callable objects and projections, and hence its {{c|operator*()}} is not defined. |
===Template parameters=== | ===Template parameters=== | ||
Revision as of 16:09, 3 October 2021
| Defined in header <iterator>
|
||
| template< std::indirectly_readable I, std::indirectly_regular_unary_invocable<I> Proj > |
(1) | (since C++20) |
| template< std::weakly_incrementable I, class Proj > struct incrementable_traits<std::projected<I, Proj>> { |
(2) | (since 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 only used 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
|
