Mine

    /** Construct from a path.
     * @param $path directory to iterate
     */
    function __construct($path)
    {
        parent::__construct(
            new RecursiveCachingIterator(
                new RecursiveDirectoryIterator($path, RecursiveDirectoryIterator::KEY_AS_FILENAME
                ),
                CachingIterator::CALL_TOSTRING|CachingIterator::CATCH_GET_CHILD
            ),
            parent::SELF_FIRST
        );
    }

    /** @return the current element prefixed with ASCII graphics
     */
    function current()
    {
        $tree = '';
        for ($l=0; $l < $this->getDepth(); $l++) {
            $tree .= $this->getSubIterator($l)->hasNext() ? '| ' : '  ';
        }
        return $tree . ($this->getSubIterator($l)->hasNext() ? '|-' : '\-')
               . $this->getSubIterator($l)->__toString();
    }

    /** Aggregates the inner iterator
     */
    function __call($func, $params)
    {
        return call_user_func_array(array($this->getSubIterator(), $func), $params);
    }