/* Initializes |trav| for |tree| and selects and returns a pointer to its least-valued item. Returns |NULL| if |tree| contains no nodes. */ void * avl_t_first (struct avl_traverser *trav, struct avl_table *tree) { struct avl_node *x; assert (tree != NULL && trav != NULL); trav->avl_table = tree; trav->avl_height = 0; trav->avl_generation = tree->avl_generation; x = tree->avl_root; if (x != NULL) while (x->avl_link[0] != NULL) { assert (trav->avl_height < AVL_MAX_HEIGHT); trav->avl_stack[trav->avl_height++] = x; x = x->avl_link[0]; } trav->avl_node = x; return x != NULL ? x->avl_data : NULL; }