interface AliasManagerInterface

interface AliasManagerInterface {
  
  /**
   * Given the alias, return the path it represents.
   *
   * @param string $alias
   *   An alias.
   * @param string $langcode
   *   An optional language code to look up the path in.
   *
   * @return string
   *   The path represented by alias, or the alias if no path was found.
   *
   * @throws \InvalidArgumentException
   *   Thrown when the path does not start with a slash.
   */
  public function getPathByAlias($alias, $langcode = NULL);
  
  /**
   * Given a path, return the alias.
   *
   * @param string $path
   *   A path.
   * @param string $langcode
   *   An optional language code to look up the path in.
   *
   * @return string
   *   An alias that represents the path, or path if no alias was found.
   *
   * @throws \InvalidArgumentException
   *   Thrown when the path does not start with a slash.
   */
  public function getAliasByPath($path, $langcode = NULL);
  
  /**
   * Clear internal caches in alias manager.
   *
   * @param $source
   *   Source path of the alias that is being inserted/updated. Can be omitted
   *   if entire cache needs to be flushed.
   */
  public function cacheClear($source = NULL);

}