/* Refreshes the stack of parent pointers in |trav|
   and updates its generation number. */
static void
trav_refresh (struct bst_traverser *trav)
{
  assert (trav != NULL);

  trav->bst_generation = trav->bst_table->bst_generation;

  if (trav->bst_node != NULL)
    {
      bst_comparison_func *cmp = trav->bst_table->bst_compare;
      void *param = trav->bst_table->bst_param;
      struct bst_node *node = trav->bst_node;
      struct bst_node *i;

      trav->bst_height = 0;
      for (i = trav->bst_table->bst_root; i != node; )
        {
          assert (trav->bst_height < BST_MAX_HEIGHT);
          assert (i != NULL);

          trav->bst_stack[trav->bst_height++] = i;
          i = i->bst_link[cmp (node->bst_data, i->bst_data, param) > 0];
        }
    }
}