X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FAtom.java;h=a9e89814225a8de049de9e2f062ddad58f09f13b;hp=0722d0b8d571905990655c76849c840e21e3de24;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=0a0227b9180534d2a431f3d6e08a398bde2244c4

diff --git a/src/edu/berkeley/sbp/Atom.java b/src/edu/berkeley/sbp/Atom.java
index 0722d0b..a9e8981 100644
--- a/src/edu/berkeley/sbp/Atom.java
+++ b/src/edu/berkeley/sbp/Atom.java
@@ -1,30 +1,29 @@
+// (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.*;
-
-/** an element which matches exactly one input token */
-public abstract class Atom<T extends Token> extends Element {
-
-    private final Topology<T> rt;
-
-    public Atom(Topology<T> rt) { this.rt = rt; }
 
-    Topology<T> top() { return rt; }
+/**
+ *  <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();
+
+    StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
 
-    void reachable(HashSet<Sequence.Position> h) { /* do-nothing */ }
-
-    /** equality is based on the underlying <tt>Topology</tt> */
-    public int hashCode() { return rt.hashCode(); }
-    
-    /** equality is based on the underlying <tt>Topology</tt> */
-    public boolean equals(Object o) { return o != null && o instanceof Atom && ((Atom)o).rt.equals(rt); }
-
-    /** declared abstract to force subclasses to override it in a useful manner */
-    public abstract String toString();
 }
 
+