Function rebase_expr

datafusion/sql/src/utils.rs:79–93

Rebuilds an `Expr` as a projection on top of a collection of `Expr`'s. For example, the expression `a + b < 1` would require, as input, the 2 individual columns, `a` and `b`. But, if the base expressions already contain the `a + b` result, then that may be used in lieu of the `a` and `b` columns. This is useful in the context of a query like: SELECT a + b < 1 ... GROUP BY a + b where post-aggr

(
    expr: &Expr,
    base_exprs: &[Expr],
    plan: &LogicalPlan,
)

/// individual columns `a` and `b`, but rather it is a projection against the
/// `a + b` found in the GROUP BY.
pub(crate) fn rebase_expr(
    expr: &Expr,
    base_exprs: &[Expr],
    plan: &LogicalPlan,
) -> Result<Expr> {
    expr.clone()
        .transform_down(|nested_expr| {
            if base_exprs.contains(&nested_expr) {
                Ok(Transformed::yes(expr_as_column_expr(&nested_expr, plan)?))
            } else {
                Ok(Transformed::no(nested_expr))
            }
        })
        .data()
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum CheckColumnsMustReferenceAggregatePurpose {