class PathMatcher

class PathMatcher implements PathMatcherInterface {

  /**
   * Whether the current page is the front page.
   *
   * @var bool
   */
  protected $isCurrentFrontPage;

  /**
   * The default front page.
   *
   * @var string
   */
  protected $frontPage;

  /**
   * The cache of regular expressions.
   *
   * @var array
   */
  protected $regexes;

  /**
   * The config factory service.
   *
   * @var \Drupal\Core\Config\ConfigFactoryInterface
   */
  protected $configFactory;

  /**
   * The current route match.
   *
   * @var \Drupal\Core\Routing\RouteMatchInterface
   */
  protected $routeMatch;

  /**
   * Creates a new PathMatcher.
   *
   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
   *   The config factory.
   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
   *   The current route match.
   */
  public function __construct(ConfigFactoryInterface $config_factory, RouteMatchInterface $route_match) {
    $this->configFactory = $config_factory;
    $this->routeMatch = $route_match;
  }

  /**
   * {@inheritdoc}
   */
  public function matchPath($path, $patterns) {
    if (!isset($this->regexes[$patterns])) {

      // Convert path settings to a regular expression.
      $to_replace = [
        // Replace newlines with a logical 'or'.
        '/(\\r\\n?|\\n)/',
        // Quote asterisks.
        '/\\\\\\*/',
        // Quote <front> keyword.
        '/(^|\\|)\\\\<front\\\\>($|\\|)/',
      ];
      $replacements = [
        '|',
        '.*',
        '\\1' . preg_quote($this
          ->getFrontPagePath(), '/') . '\\2',
      ];
      $patterns_quoted = preg_quote($patterns, '/');
      $this->regexes[$patterns] = '/^(' . preg_replace($to_replace, $replacements, $patterns_quoted) . ')$/';
    }
    return (bool) preg_match($this->regexes[$patterns], $path);
  }

  /**
   * {@inheritdoc}
   */
  public function isFrontPage() {

    // Cache the result as this is called often.
    if (!isset($this->isCurrentFrontPage)) {
      $this->isCurrentFrontPage = FALSE;

      // Ensure that the code can also be executed when there is no active
      // route match, like on exception responses.
      if ($this->routeMatch
        ->getRouteName()) {
        $url = Url::fromRouteMatch($this->routeMatch);
        $this->isCurrentFrontPage = $url
          ->getRouteName() && '/' . $url
          ->getInternalPath() === $this
          ->getFrontPagePath();
      }
    }
    return $this->isCurrentFrontPage;
  }

  /**
   * Gets the current front page path.
   *
   * @return string
   *   The front page path.
   */
  protected function getFrontPagePath() {

    // Lazy-load front page config.
    if (!isset($this->frontPage)) {
      $this->frontPage = $this->configFactory
        ->get('system.site')
        ->get('page.front');
    }
    return $this->frontPage;
  }

}