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..daa3d49 100644 (file)
--- a/src/edu/berkeley/sbp/Atom.java
+++ b/src/edu/berkeley/sbp/Atom.java
@@ -7,24 +7,24 @@ 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 {
+/**
+ *  <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 Frege'd
+ *  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();
+
+    StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
 
-    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();
 }
 
+