Method unproject_expr

datafusion/physical-expr/src/projection.rs:492–503

"unproject" an expression by applying this projection in reverse, returning a new set of expressions that reference the original input columns. For example, consider an expression `c1_c2 > 5`, and a schema `[c1, c2]` a projection `c1 + c2 as c1_c2` This method would rewrite the expression to `c1 + c2 > 5`

(
        &self,
        expr: &Arc<dyn PhysicalExpr>,
    )

    ///
    /// This method would rewrite the expression to `c1 + c2 > 5`
    pub fn unproject_expr(
        &self,
        expr: &Arc<dyn PhysicalExpr>,
    ) -> Result<Arc<dyn PhysicalExpr>> {
        update_expr(expr, &self.exprs, true)?.ok_or_else(|| {
            internal_datafusion_err!(
                "Failed to unproject an expression {} with ProjectionExprs {}",
                expr,
                self.exprs.iter().map(|e| format!("{e}")).join(", ")
            )
        })
    }

    /// "project" an expression using these projection's expressions
    ///