IsFrontPathCacheContext.php

<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Path\PathMatcherInterface;

/**
 * Defines a cache context for whether the URL is the front page of the site.
 *
 * Cache context ID: 'url.path.is_front'.
 */
class IsFrontPathCacheContext implements CacheContextInterface {
    
    /**
     * @var \Drupal\Core\Path\PathMatcherInterface
     */
    protected $pathMatcher;
    
    /**
     * Constructs an IsFrontPathCacheContext object.
     *
     * @param \Drupal\Core\Path\PathMatcherInterface $path_matcher
     *   The path matcher.
     */
    public function __construct(PathMatcherInterface $path_matcher) {
        $this->pathMatcher = $path_matcher;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t('Is front page');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext() {
        return 'is_front.' . (int) $this->pathMatcher
            ->isFrontPage();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata() {
        $metadata = new CacheableMetadata();
        $metadata->addCacheTags([
            'config:system.site',
        ]);
        return $metadata;
    }

}