Method projected

src/lib.rs:550–577

(
        self,
        _nested: &mut Iterative<'a, G, u64>,
        _context: &mut I,
        target_variables: &[Var],
    )

    }

    fn projected(
        self,
        _nested: &mut Iterative<'a, G, u64>,
        _context: &mut I,
        target_variables: &[Var],
    ) -> (
        Collection<Iterative<'a, G, u64>, Vec<Value>, isize>,
        ShutdownHandle,
    ) {
        if self.variables() == target_variables {
            (self.tuples, ShutdownHandle::empty())
        } else {
            let relation_variables = self.variables();
            let target_variables = target_variables.to_vec();

            let tuples = self.tuples.map(move |tuple| {
                target_variables
                    .iter()
                    .map(|x| {
                        let idx = relation_variables.binds(*x).unwrap();
                        tuple[idx].clone()
                    })
                    .collect()
            });

            (tuples, ShutdownHandle::empty())
        }
    }

    fn tuples_by_variables(
        self,