Implemented by objects responsible for text serialization and deserialization of Place objects.

@param <P> a subtype of {@link Place}

abstract class PlaceTokenizer<P extends Place> {

 /**
  * Returns the {@link Place} associated with the given token.
  *
  * @param token a String token
  * @return a {@link Place} of type P
  */
 P getPlace(String token);

 /**
  * Returns the token associated with the given {@link Place}.
  *
  * @param place a {@link Place} of type P
  * @return a String token
  */
 String getToken(P place);
}