Namespaces
Variants

std::experimental::ranges:: projected

From cppreference.net
C++
Experimental
Ranges
Iterators library
Iterator concepts
Indirect callable concepts
Common algorithm requirements
Concept utilities
projected
Iterator utilities and operations
Iterator traits
Iterator adaptors
Stream iterators
template < Readable I, IndirectRegularUnaryInvocable < I > Proj >

struct projected {
using value_type =
std:: remove_cv_t < std:: remove_reference_t < ranges :: indirect_result_of_t < Proj & ( I ) >>> ;
ranges :: indirect_result_of_t < Proj & ( I ) > operator * ( ) const ;
} ;

template < WeaklyIncrementable I, class Proj >
struct difference_type < projected < I, Proj >> {
using type = ranges :: difference_type_t < I > ;

} ;
(ranges TS)

类模板 projected 将一个 Readable 类型 I 与函数 Proj 组合成新的 Readable 类型，其 reference 类型是将 Proj 应用于 I 的 reference 类型的结果。该模板仅用于简化约束规范，因此其 operator * ( ) 可能并未实际定义。