private function generateFillSlots(PHPTAL_Php_CodeWriter $codewriter, PHPTAL_Dom_Node $phpelement)
    {
        if (false == ($phpelement instanceof PHPTAL_Dom_Element)) {
            return;
        }

        // if the tag contains one of the allowed attribute, we generate it
        foreach (self::$ALLOWED_ATTRIBUTES as $qname => $uri) {
            if ($phpelement->hasAttributeNS($uri, $qname)) {
                $phpelement->generateCode($codewriter);
                return;
            }
        }

        foreach ($phpelement->childNodes as $child) {
            $this->generateFillSlots($codewriter, $child);
        }
    }