protected static function cutFromDom($current, $length) {
        $i = 0;
        while($i < $current->childNodes->length) {
            $node = $current->childNodes->item($i);
            if($length > 0) {
                switch ($node->type) {
                    case XML_TEXT_NODE:
                    case XML_CDATA_SECTION_NODE:
                        $node->textContent = mb_substr($node->textContent, 0, $length);
                        $length -= mb_strlen($node->textContent);
                        break;
                    case XML_ELEMENT_NODE:
                        $length = self::cutFromDom($node, $length);
                        break;
                }
                $i++;
            }
            else {
                $current->removeChild($node);
            }
        }
        return $length;
    }