/* Initializes |trav| for |tree|.
   Returns data item in |tree| with the greatest value,
   or |NULL| if |tree| is empty. */
void *
rtbst_t_last (struct rtbst_traverser *trav, struct rtbst_table *tree)
{
  assert (tree != NULL && trav != NULL);

  trav->rtbst_table = tree;
  trav->rtbst_node = tree->rtbst_root;
  if (trav->rtbst_node != NULL)
    {
      while (trav->rtbst_node->rtbst_rtag == RTBST_CHILD)
        trav->rtbst_node = trav->rtbst_node->rtbst_link[1];
      return trav->rtbst_node->rtbst_data;
    }
  else
    return NULL;
}