Function unwrap_certainly_null_expr

datafusion/expr/src/expr_schema.rs:746–753

Returns the innermost [Expr] that is provably null if `expr` is null.

(expr: &Expr)

/// Returns the innermost [Expr] that is provably null if `expr` is null.
fn unwrap_certainly_null_expr(expr: &Expr) -> &Expr {
    match expr {
        Expr::Not(e) => unwrap_certainly_null_expr(e),
        Expr::Negative(e) => unwrap_certainly_null_expr(e),
        Expr::Cast(e) => unwrap_certainly_null_expr(e.expr.as_ref()),
        _ => expr,
    }
}

/// Cast subquery in InSubquery/ScalarSubquery to a given type.
///