private function registerFilters()
    {
        $filters = config('app.render_filters', []);

        foreach ($filters as $filter) {
            $filter = app($filter);

            if ($filter instanceof FilterContract) {
                $this->twigEnvironment->addFilter(new \Twig_SimpleFilter($filter->getName(), $filter->getFilter()));
                $this->twigStringEnvironment->addFilter(new \Twig_SimpleFilter($filter->getName(),
                    $filter->getFilter()));
            }
        }
    }