import edu.berkeley.sbp.*;
import edu.berkeley.sbp.*;
-/** <font color=green>an element which matches exactly one input token</font> */
+/**
+ * <font color=green>an element which matches some set of one-token-long input strings</font>.
+ *
+ * This class is a topology over itself so that Atoms can be
+ * intersected and unioned with each other to result in other
+ * Atom<T>'s (rather than raw Topology<T>'s, which are not Elements).
+ * If you want the latter, use the getTokenTopology() method.
+ */
public abstract class Atom<T> extends Element implements Topology<Atom<T>> {
- public abstract Topology<T> underlying();
- public abstract String toString();
- public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
+ /** the set (topology) of tokens that can match this element */
+ public abstract Topology<T> getTokenTopology();
+ public abstract StringBuffer toString(StringBuffer sb);
}