/* Searches for |item| in |tree|.
   If found, initializes |trav| to the item found and returns the item
   as well.
   If there is no matching item, initializes |trav| to the null item
   and returns |NULL|. */
void *
rtbst_t_find (struct rtbst_traverser *trav, struct rtbst_table *tree,
              void *item)
{
  struct rtbst_node *p;

  assert (trav != NULL && tree != NULL && item != NULL);

  trav->rtbst_table = tree;
  trav->rtbst_node = NULL;

  p = tree->rtbst_root;
  if (p == NULL)
    return NULL;

  for (;;)
    {
      int cmp = tree->rtbst_compare (item, p->rtbst_data, tree->rtbst_param);
      if (cmp == 0)
        {
          trav->rtbst_node = p;
          return p->rtbst_data;
        }

      if (cmp < 0)
        {
          p = p->rtbst_link[0];
          if (p == NULL)
            return NULL;
        }
      else
        {
          if (p->rtbst_rtag == RTBST_THREAD)
            return NULL;
          p = p->rtbst_link[1];
        }
    }
}