private function buildSimpleDirective($key, $value)
    {
        $known = $this->parser->getServer()->getKnownDirectives();
        if (in_array($key, array_keys($known))) {
            if (isset($known[$key]['class'])) {
                $class = 'WebHelper\Parser\Directive\\'.$known[$key]['class'];
                return new $class($key, $value, $this->parser);
            }
        }

        return new SimpleDirective($key, $value);
    }