+// 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.*;
-/** <font color=green>an element which matches exactly one input token</font> */
-public abstract class Atom<T> extends Element implements Topology<T> {
-
- protected abstract Topology<T> top();
- public abstract String toString();
- public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
+/**
+ * <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>> {
- // Topology Thunks //////////////////////////////////////////////////////////////////////////////
+ /** the set (topology) of tokens that can match this element */
+ public abstract Topology<Token> getTokenTopology();
- public Topology<T> unwrap() { return top().unwrap(); }
- public Topology<T> empty() { return top().empty(); }
- public boolean contains(T v) { return top().contains(v); }
- public Topology<T> intersect(Topology<T> t) { return top().intersect(t); }
- public Topology<T> minus(Topology<T> t) { return top().minus(t); }
- public Topology<T> union(Topology<T> t) { return top().union(t); }
- public Topology<T> complement() { return top().complement(); }
- public boolean disjoint(Topology<T> t) { return top().disjoint(t); }
- public boolean containsAll(Topology<T> t) { return top().containsAll(t); }
- public int hashCode() { return top().hashCode(); }
- public boolean equals(Object o) { return o != null && o instanceof Atom && ((Atom)o).top().equals(top()); }
+ StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
}
+