RegisterEventSubscribersPass::process

public RegisterEventSubscribersPass::process(ContainerBuilder $container)

public function process(ContainerBuilder $container) {
  if (!$container->hasDefinition('event_dispatcher')) {
    return;
  }

  $definition = $container->getDefinition('event_dispatcher');

  $event_subscriber_info = [];
  foreach ($container->findTaggedServiceIds('event_subscriber') as $id => $attributes) {

    // We must assume that the class value has been correctly filled, even if
    // the service is created by a factory.
    $class = $container->getDefinition($id)->getClass();

    $refClass = new \ReflectionClass($class);
    $interface = 'Symfony\Component\EventDispatcher\EventSubscriberInterface';
    if (!$refClass->implementsInterface($interface)) {
      throw new \InvalidArgumentException(sprintf('Service "%s" must implement interface "%s".', $id, $interface));
    }

    // Get all subscribed events.
    foreach ($class::getSubscribedEvents() as $event_name => $params) {
      if (is_string($params)) {
        $priority = 0;
        $event_subscriber_info[$event_name][$priority][] = ['service' => [$id, $params]];
      }
      elseif (is_string($params[0])) {
        $priority = isset($params[1]) ? $params[1] : 0;
        $event_subscriber_info[$event_name][$priority][] = ['service' => [$id, $params[0]]];
      }
      else {
        foreach ($params as $listener) {
          $priority = isset($listener[1]) ? $listener[1] : 0;
          $event_subscriber_info[$event_name][$priority][] = ['service' => [$id, $listener[0]]];
        }
      }
    }
  }

  foreach (array_keys($event_subscriber_info) as $event_name) {
    krsort($event_subscriber_info[$event_name]);
  }

  $definition->addArgument($event_subscriber_info);
}