Only apply JSONP(adding) via a Silex after filter on configured routes

gistfile1.php

$app->after(function (Request $request, Response $response) {
    $appl = $request->attributes->get('app');

    if ($request->get('jsonp_callback') !== null 
        && $request->getMethod() === 'GET') 
    {
       /** 
        * Configured via ConfigServiceProvider (https://github.com/igorw/ConfigServiceProvider)
        * Example:
        *      
        * $config['jsonp_able_route_patterns'] = array(
        *     '/{query}', 
        *     '/teaser/{amount}'
        * );
        */
        $jsonpAbleRoutePatterns = $appl['jsonp_able_route_patterns'];
        $actualRouteKey = str_replace('GET_', '', $request->attributes->get('_route'));
        $routes = $appl['routes']->all();

        foreach ($routes as $routeKey => $route) {
            $routeKey = str_replace('GET_', '', $routeKey);
            if ($routeKey === $actualRouteKey 
                && !in_array($route->getPattern(), $jsonpAbleRoutePatterns)) 
            {
                return;
            }
        }
        $response->headers->set('Content-Type', 'application/javascript');
        $response->setContent($request->get('jsonp_callback') . '(' . $response->getContent() . ');');
    }
});

or globally add it

$app->after(function (Request $request, Response $response) {
    if(($response instanceof \Symfony\Component\HttpFoundation\JsonResponse) && $request->get('jsonp_callback')) {
        $response->setCallback($request->get('jsonp_callback'));
    }
});