/*
 *  call-seq:
 *     pq.clone -> pq_clone
 *  
 *  Returns a shallow clone of the priority queue. That is only the priority
 *  queue is cloned, its contents are not cloned.
 */
static VALUE
frt_pq_clone(VALUE self)
{
    PriQ *pq, *new_pq = ALLOC(PriQ);
    GET_PQ(pq, self);
    memcpy(new_pq, pq, sizeof(PriQ));
    new_pq->heap = ALLOC_N(VALUE, new_pq->mem_capa);
    memcpy(new_pq->heap, pq->heap, sizeof(VALUE) * (new_pq->size + 1));

    return Data_Wrap_Struct(cPriorityQueue, &frt_pq_mark, &frt_pq_free, new_pq);
}