Function find_agg_node_within_select

datafusion/sql/src/unparser/utils.rs:42–73

Recursively searches children of [LogicalPlan] to find an Aggregate node if exists prior to encountering a Join, TableScan, or a nested subquery (derived table factor). If an Aggregate or node is not found prior to this or at all before reaching the end of the tree, None is returned.

(
    plan: &LogicalPlan,
    already_projected: bool,
)

/// If an Aggregate or node is not found prior to this or at all before reaching the end
/// of the tree, None is returned.
pub(crate) fn find_agg_node_within_select(
    plan: &LogicalPlan,
    already_projected: bool,
) -> Option<&Aggregate> {
    // Note that none of the nodes that have a corresponding node can have more
    // than 1 input node. E.g. Projection / Filter always have 1 input node.
    let input = plan.inputs();
    let input = if input.len() > 1 {
        return None;
    } else {
        input.first()?
    };
    // Agg nodes explicitly return immediately with a single node
    if let LogicalPlan::Aggregate(agg) = input {
        Some(agg)
    } else if matches!(
        input,
        LogicalPlan::TableScan(_)
            | LogicalPlan::Subquery(_)
            | LogicalPlan::SubqueryAlias(_)
    ) {
        None
    } else if let LogicalPlan::Projection(_) = input {
        if already_projected {
            None
        } else {
            find_agg_node_within_select(input, true)
        }
    } else {
        find_agg_node_within_select(input, already_projected)
    }
}

/// Recursively searches children of [LogicalPlan] to find Unnest node if exist
pub(crate) fn find_unnest_node_within_select(plan: &LogicalPlan) -> Option<&Unnest> {