import edu.berkeley.sbp.*;
import edu.berkeley.sbp.*;
-/** an element which matches exactly one input token */
-public abstract class Atom<T> extends Element implements Topology<T> {
+/** <font color=green>an element which matches exactly one input token</font> */
+public abstract class Atom<T> extends Element implements Topology<Atom<T>> {
- protected abstract Topology<T> top();
+ public abstract Topology<T> underlying();
public abstract String toString();
public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
- // Topology Thunks //////////////////////////////////////////////////////////////////////////////
-
- 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()); }
-
- /** if all expressions matching <tt>e</tt> are exactly one token
- * long, <b>attempt to</b> return an Atom representing that token
- * (undecidable in general; only works in trivial cases)
- */
- public static Topology toAtom(Element e) {
- if (e instanceof Atom) return (Atom)e;
- if (e instanceof Sequence) return ((Sequence)e).toAtom();
- Topology ret = null;
- for(Sequence s : (Union)e)
- ret = ret==null ? toAtom(s) : ret.union(s.toAtom());
- return ret;
- }
}