ModuleRouteSubscriber.php

<?php

namespace Drupal\Core\EventSubscriber;

use Drupal\Core\Extension\ModuleHandlerInterface;
use Drupal\Core\Routing\RouteSubscriberBase;
use Symfony\Component\Routing\RouteCollection;

/**
 * A route subscriber to remove routes that depend on modules being enabled.
 */
class ModuleRouteSubscriber extends RouteSubscriberBase {
    
    /**
     * The module handler.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * Constructs a ModuleRouteSubscriber object.
     *
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     */
    public function __construct(ModuleHandlerInterface $module_handler) {
        $this->moduleHandler = $module_handler;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function alterRoutes(RouteCollection $collection) {
        foreach ($collection as $name => $route) {
            if ($route->hasRequirement('_module_dependencies')) {
                $modules = $route->getRequirement('_module_dependencies');
                $explode_and = $this->explodeString($modules, '+');
                if (count($explode_and) > 1) {
                    foreach ($explode_and as $module) {
                        // If any moduleExists() call returns FALSE, remove the route and
                        // move on to the next.
                        if (!$this->moduleHandler
                            ->moduleExists($module)) {
                            $collection->remove($name);
                            continue 2;
                        }
                    }
                }
                else {
                    // OR condition, exploding on ',' character.
                    foreach ($this->explodeString($modules, ',') as $module) {
                        if ($this->moduleHandler
                            ->moduleExists($module)) {
                            continue 2;
                        }
                    }
                    // If no modules are found, and we get this far, remove the route.
                    $collection->remove($name);
                }
            }
        }
    }
    
    /**
     * Explodes a string based on a separator.
     *
     * @param string $string
     *   The string to explode.
     * @param string $separator
     *   The string separator to explode with.
     *
     * @return array
     *   An array of exploded (and trimmed) values.
     */
    protected function explodeString($string, $separator = ',') {
        return array_filter(array_map('trim', explode($separator, $string)));
    }

}