Function transformGroupClauseList

src/backend/parser/parse_clause.c:2561–2593

* Transform a list of expressions within a GROUP BY clause or grouping set. * * The list of expressions belongs to a single clause within which duplicates * can be safely eliminated. * * Returns an integer list of ressortgroupref values. * * flatresult reference to flat list of SortGroupClause nodes * pstate ParseState * list nodes to transform * targetlist reference to TargetEntry li

 * toplevel		false if within any grouping set
 */
static List *
transformGroupClauseList(List **flatresult,
						 ParseState *pstate, List *list,
						 List **targetlist, List *sortClause,
						 ParseExprKind exprKind, bool useSQL99, bool toplevel)
{
	Bitmapset  *seen_local = NULL;
	List	   *result = NIL;
	ListCell   *gl;

	foreach(gl, list)
	{
		Node	   *gexpr = (Node *) lfirst(gl);

		Index		ref = transformGroupClauseExpr(flatresult,
												   seen_local,
												   pstate,
												   gexpr,
												   targetlist,
												   sortClause,
												   exprKind,
												   useSQL99,
												   toplevel);

		if (ref > 0)
		{
			seen_local = bms_add_member(seen_local, ref);
			result = lappend_int(result, ref);
		}
	}

	return result;
}

/*
 * Transform a grouping set and (recursively) its content.