Function collect_grouping_from_expr

nodedb-sql/src/planner/aggregate.rs:289–325

Recursively collect `GROUPING(col)` calls from an expression.

(
    expr: &ast::Expr,
    alias: &str,
    canonical_keys: &[SqlExpr],
    out: &mut Vec<AggregateExpr>,
)

/// Recursively collect `GROUPING(col)` calls from an expression.
fn collect_grouping_from_expr(
    expr: &ast::Expr,
    alias: &str,
    canonical_keys: &[SqlExpr],
    out: &mut Vec<AggregateExpr>,
) -> Result<()> {
    match expr {
        ast::Expr::Function(f) => {
            let name = normalize_function_name(f);
            if name.eq_ignore_ascii_case("grouping") {
                // Extract the column argument(s).
                let args = function_args_exprs(f);
                for col_expr in &args {
                    let canonical_idx = crate::planner::grouping_sets::resolve_grouping_col(
                        col_expr,
                        canonical_keys,
                    )?;
                    // Encode index in the field name; alias is user-visible output name.
                    out.push(AggregateExpr {
                        function: "grouping".into(),
                        args: vec![convert_expr(col_expr)?],
                        alias: alias.to_string(),
                        distinct: false,
                        grouping_col_index: Some(canonical_idx),
                    });
                }
            }
        }
        // Recurse into binary ops and other wrappers.
        ast::Expr::BinaryOp { left, right, .. } => {
            collect_grouping_from_expr(left, alias, canonical_keys, out)?;
            collect_grouping_from_expr(right, alias, canonical_keys, out)?;
        }
        _ => {}
    }
    Ok(())
}

/// Extract the positional expression arguments from a function call.
fn function_args_exprs(f: &ast::Function) -> Vec<&ast::Expr> {