SessionExistsCacheContext.php

<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Session\SessionConfigurationInterface;
use Symfony\Component\HttpFoundation\RequestStack;

/**
 * Defines the SessionExistsCacheContext service, for "session or not" caching.
 *
 * Cache context ID: 'session.exists'.
 */
class SessionExistsCacheContext implements CacheContextInterface {
    
    /**
     * The session configuration.
     *
     * @var \Drupal\Core\Session\SessionConfigurationInterface
     */
    protected $sessionConfiguration;
    
    /**
     * The request stack.
     *
     * @var \Symfony\Component\HttpFoundation\RequestStack
     */
    protected $requestStack;
    
    /**
     * Constructs a new SessionExistsCacheContext class.
     *
     * @param \Drupal\Core\Session\SessionConfigurationInterface $session_configuration
     *   The session configuration.
     * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
     *   The request stack.
     */
    public function __construct(SessionConfigurationInterface $session_configuration, RequestStack $request_stack) {
        $this->sessionConfiguration = $session_configuration;
        $this->requestStack = $request_stack;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t('Session exists');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext() {
        return $this->sessionConfiguration
            ->hasSession($this->requestStack
            ->getCurrentRequest()) ? '1' : '0';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata() {
        return new CacheableMetadata();
    }

}