+// (C) 2006-2007 all rights reserved; see LICENSE file for BSD-style license
+
package edu.berkeley.sbp;
-import java.io.*;
-import java.util.*;
-import java.lang.reflect.*;
-import java.lang.ref.*;
import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
-import edu.berkeley.sbp.*;
-/** <font color=green>an element which matches exactly one input token</font> */
-public abstract class Atom<T> extends Element implements Topology<Atom<T>> {
+/**
+ * <font color=green>
+ * an element which matches some set of one-token-long input strings
+ * </font>.
+ *
+ * <p>
+ * 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 <i>tokens</i> which this
+ * Atom can match, use the <tt>getTokenTopology()</tt> method.
+ * </p>
+ */
+public abstract class Atom<Token>
+ extends Element
+ implements Topology<Atom<Token>> {
+
+ /** the set (topology) of tokens that can match this element */
+ public abstract Topology<Token> getTokenTopology();
- public abstract Topology<T> underlying();
- public abstract String toString();
- public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
+ StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
}
+