AdminContext.php

<?php

namespace Drupal\Core\Routing;

use Symfony\Component\Routing\Route;

/**
 * Provides a helper class to determine whether the route is an admin one.
 */
class AdminContext {
    
    /**
     * The route match.
     *
     * @var \Drupal\Core\Routing\RouteMatchInterface
     */
    protected $routeMatch;
    
    /**
     * Construct a new admin context helper instance.
     *
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   The route match.
     */
    public function __construct(RouteMatchInterface $route_match) {
        $this->routeMatch = $route_match;
    }
    
    /**
     * Determines whether the active route is an admin one.
     *
     * @param \Symfony\Component\Routing\Route $route
     *   (optional) The route to determine whether it is an admin one. Per default
     *   this falls back to the route object on the active request.
     *
     * @return bool
     *   Returns TRUE if the route is an admin one, otherwise FALSE.
     */
    public function isAdminRoute(?Route $route = NULL) {
        if (!$route) {
            $route = $this->routeMatch
                ->getRouteObject();
            if (!$route) {
                return FALSE;
            }
        }
        return (bool) $route->getOption('_admin_route');
    }

}