std::experimental::ranges:: Relation

The concept Relation<R, T, U> specifies that R defines a binary relation over the set of expressions whose type and value category are those encoded by either T or U .

Given

• r , an expression such that decltype ( ( r ) ) is R ,
• t , an expression such that decltype ( ( t ) ) is T ,
• u , an expression such that decltype ( ( u ) ) is U ,

and let C be ranges:: common_reference_t < const std:: remove_reference_t < T > & , const std:: remove_reference_t < U > & > ,

then Relation<R, T, U> is satisfied only if

• bool ( r ( t, u ) ) == bool ( r ( C ( t ) , C ( u ) ) ) and
• bool ( r ( u, t ) ) == bool ( r ( C ( u ) , C ( t ) ) ) .