MenuActiveTrailsCacheContext.php

<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;
use Symfony\Component\DependencyInjection\ContainerAwareInterface;
use Symfony\Component\DependencyInjection\ContainerAwareTrait;

/**
 * Defines the MenuActiveTrailsCacheContext service.
 *
 * This class is container-aware to avoid initializing the 'menu.active_trails'
 * service (and its dependencies) when it is not necessary.
 */
class MenuActiveTrailsCacheContext implements CalculatedCacheContextInterface, ContainerAwareInterface {
    use ContainerAwareTrait;
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t("Active menu trail");
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext($menu_name = NULL) {
        if (!$menu_name) {
            throw new \LogicException('No menu name provided for menu.active_trails cache context.');
        }
        $active_trail = $this->container
            ->get('menu.active_trail')
            ->getActiveTrailIds($menu_name);
        return 'menu_trail.' . $menu_name . '|' . implode('|', $active_trail);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata($menu_name = NULL) {
        if (!$menu_name) {
            throw new \LogicException('No menu name provided for menu.active_trails cache context.');
        }
        $cacheable_metadata = new CacheableMetadata();
        return $cacheable_metadata->setCacheTags([
            "config:system.menu.{$menu_name}",
        ]);
    }

}