Function foreach_with_count

src/backend/gpopt/utils/COptTasks.cpp:606–632

	ListCell *l;
	int count = 0;
	foreach_with_count(l, relations, count)
	{
		char *relation = (char *) lfirst(l);
		if (aliases.count(std::string(relation)) > 0)
		{
			pair->Release();
			// invalid leading hint if alias is specified more than once
			return nullptr;
		}
		aliases.insert(std::string(relation));

		CWStringConst *alias = GPOS_NEW(mp) CWStringConst(mp, relation);

		if (count == 0)
		{
			// As we traverse the input list relations, we build up the
			// JoinNode pair. The first element is an edge case because there
			// is no existing JoinNode pair yet.
			pair = GPOS_NEW(mp) CJoinHint::JoinNode(alias);
		}
		else
		{
			pair = GPOS_NEW(mp) CJoinHint::JoinNode(
				pair, GPOS_NEW(mp) CJoinHint::JoinNode(alias),
				/*is_directed*/ false);
		}
	}

	return pair;
}