's, which are not Elements).
- * If you want the latter, use the getTokenTopology() method.
+ *
+ * This class is a topology over itself (yes, this is impredicative).
+ * This means that you can call Atom.union(Atom) and get back an Atom.
+ * If you are interested in the topology of tokens which this
+ * Atom can match, use the getTokenTopology() method.
+ *
*/
-public abstract class Atom extends Element implements Topology> {
+public abstract class Atom
+ extends Element
+ implements Topology> {
/** the set (topology) of tokens that can match this element */
- public abstract Topology getTokenTopology();
+ public abstract Topology getTokenTopology();
+
+ StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
- public abstract StringBuffer toString(StringBuffer sb);
}
+