X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FAtom.java;h=e02b79f816c0a95039abcf9e67206563cb3e5e4c;hb=b910ad546f02d07664d32a70ce9acf6f049a64b1;hp=306e126e0e49a2f69561452ae038a8d77bc03c37;hpb=b320f26b6e2cc13dcfcd810c7d5b507b942e8c70;p=sbp.git

diff --git a/src/edu/berkeley/sbp/Atom.java b/src/edu/berkeley/sbp/Atom.java
index 306e126..e02b79f 100644
--- a/src/edu/berkeley/sbp/Atom.java
+++ b/src/edu/berkeley/sbp/Atom.java
@@ -1,3 +1,5 @@
+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
 package edu.berkeley.sbp;
 import java.io.*;
 import java.util.*;
@@ -7,12 +9,25 @@ 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, that's sort of <a
+ *  href=http://en.wikipedia.org/wiki/Frege>Frege'd</a> up) so that
+ *  Atoms can be intersected and unioned with each other to result in
+ *  other Atom<Token>'s (rather than raw Topology<Token>'s, which are
+ *  not Elements).  If you want the latter, use the getTokenTopology()
+ *  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; }
 
 }
 
+