#endif
pdeq *l_end, *r_end; /**< left and right ends of the queue */
pdeq *l, *r; /**< left and right neighbor */
#endif
pdeq *l_end, *r_end; /**< left and right ends of the queue */
pdeq *l, *r; /**< left and right neighbor */
&& ((q == dq->l_end) ^ (q->l != NULL))
&& ((q == dq->r_end) ^ (q->r != NULL))
&& (!q->l || (q == q->l->r))
&& ((q == dq->l_end) ^ (q->l != NULL))
&& ((q == dq->r_end) ^ (q->r != NULL))
&& (!q->l || (q == q->l->r))