text: <?php
  
  /*
   * This file is part of the Symfony package.
   *
   * (c) Fabien Potencier <fabien@symfony.com>
   *
   * For the full copyright and license information, please view the LICENSE
   * file that was distributed with this source code.
   */
  
  namespace Symfony\Component\HttpKernel\CacheWarmer;
  
  /**
   * Interface for classes able to warm up the cache.
   *
   * @author Fabien Potencier <fabien@symfony.com>
   */
  interface CacheWarmerInterface extends WarmableInterface
  {
      /**
       * Checks whether this warmer is optional or not.
       *
       * Optional warmers can be ignored on certain conditions.
       *
       * A warmer should return true if the cache can be
       * generated incrementally and on-demand.
       *
       * @return bool true if the warmer is optional, false otherwise
       */
      public function isOptional();
  }
  