Function expr_as_column_expr

datafusion/expr/src/utils.rs:823–833

Convert any `Expr` to an `Expr::Column`.

(expr: &Expr, plan: &LogicalPlan)

/// Convert any `Expr` to an `Expr::Column`.
pub fn expr_as_column_expr(expr: &Expr, plan: &LogicalPlan) -> Result<Expr> {
    match expr {
        Expr::Column(col) => {
            let (qualifier, field) = plan.schema().qualified_field_from_column(col)?;
            Ok(Expr::from(Column::from((qualifier, field))))
        }
        _ => Ok(Expr::Column(Column::from_name(
            expr.schema_name().to_string(),
        ))),
    }
}

/// Recursively walk an expression tree, collecting the column indexes
/// referenced in the expression