function Text_Diff3($orig, $final1, $final2)
    {
        if (extension_loaded('xdiff')) {
            $engine = new Text_Diff_Engine_xdiff();
        } else {
            $engine = new Text_Diff_Engine_native();
        }

        $this->_edits = $this->_diff3($engine->diff($orig, $final1),
                                      $engine->diff($orig, $final2));
    }