+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
package edu.berkeley.sbp;
import java.io.*;
import java.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 implements Topology<T> {
-
- 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 */ }
+/**
+ * <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();
+
+ StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
- /** 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();
-
- // Topology Thunks //////////////////////////////////////////////////////////////////////////////
-
- public void add(Topology<T> t) { rt.add(t); }
- public void add(T t) { rt.add(t); }
- public void remove(Topology<T> t) { rt.remove(t); }
- public void remove(T t) { rt.remove(t); }
- public Topology<T> dup() { return rt.dup(); }
- public boolean contains(T v) { return rt.contains(v); }
- public Topology<T> fresh() { return rt.fresh(); }
- public Topology<T> intersect(Topology<T> t) { return rt.intersect(t); }
- public Topology<T> minus(Topology<T> t) { return rt.minus(t); }
- public Topology<T> union(Topology<T> t) { return rt.union(t); }
- public Topology<T> complement() { return rt.complement(); }
- public boolean disjoint(Topology<T> t) { return rt.disjoint(t); }
- public boolean containsAll(Topology<T> t) { return rt.containsAll(t); }
-
}
+