checkpoint

[sbp.git] / src / edu / berkeley / sbp / Atom.java

diff --git a/src/edu/berkeley/sbp/Atom.java b/src/edu/berkeley/sbp/Atom.java
index 0722d0b..0a8ad12 100644 (file)
--- a/src/edu/berkeley/sbp/Atom.java
+++ b/src/edu/berkeley/sbp/Atom.java
@@ -7,24 +7,19 @@ 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; }
-
-    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();
+/**
+ *  <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>> {
+
+    /** the set (topology) of tokens that can match this element */
+    public abstract Topology<T>  getTokenTopology();
+
+    public abstract StringBuffer toString(StringBuffer sb);
 }