LoginStatusCheck.php

<?php

namespace Drupal\user\Access;

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Routing\Access\AccessInterface;
use Drupal\Core\Session\AccountInterface;
use Symfony\Component\Routing\Route;

/**
 * Determines access to routes based on login status of current user.
 */
class LoginStatusCheck implements AccessInterface {
    
    /**
     * Checks access.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The currently logged in account.
     * @param \Symfony\Component\Routing\Route $route
     *   The route to check against.
     *
     * @return \Drupal\Core\Access\AccessResultInterface
     *   The access result.
     */
    public function access(AccountInterface $account, Route $route) {
        $required_status = filter_var($route->getRequirement('_user_is_logged_in'), FILTER_VALIDATE_BOOLEAN);
        $actual_status = $account->isAuthenticated();
        $access_result = AccessResult::allowedIf($required_status === $actual_status)->addCacheContexts([
            'user.roles:authenticated',
        ]);
        if (!$access_result->isAllowed()) {
            $access_result->setReason($required_status === TRUE ? 'This route can only be accessed by authenticated users.' : 'This route can only be accessed by anonymous users.');
        }
        return $access_result;
    }

}