protected function _analyseChildren($xml)
    {
        // $reg2 = "#\[!--\sBEGIN\s([\S]*)\s--\](?:<\/text:p>)?(.*)(?:<text:p\s.*>)?\[!--\sEND\s(\\1)\s--\]#sm";
        $reg2 = "#\[!--\sBEGIN\s([\S]*)\s--\](.*)\[!--\sEND\s(\\1)\s--\]#smU";
        preg_match_all($reg2, $xml, $matches);
        for ($i = 0, $size = count($matches[0]); $i < $size; $i++) {
            if ($matches[1][$i] != $this->name) {
                $this->children[$matches[1][$i]] = new self($matches[1][$i], $matches[0][$i], $this->odf);
            } else {
                $this->_analyseChildren($matches[2][$i]);
            }
        }
        return $this;
    }