10.6.3 Starting at a Found Node

To start from an item found in the tree, we use the same algorithm as rtbst_find().

400. <RTBST traverser search initializer 400> =
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];
        }
    }
}

This code is included in 397.