Двусторонняя навигация

ListItem *forwardIterator(const ListItem *item) { return item->next; }
ListItem *reversedIterator(const ListItem *item) { return item->prev; }

void testIterator(List *list, bool isForward) {
    ListItem *(*iterator)(const ListItem *) = isForward ? forwardIterator : reversedIterator;

    for (ListItem *item = isForward ? list->head : list->tail; item; item = iterator(item)) {
        //TODO:
        printf("%u ", item->employee.employeeId);
    }
}