import edu.berkeley.sbp.*;
/** an element which matches exactly one input token */
-public abstract class Atom<T extends Token> extends Element implements Topology<T> {
+public abstract class Atom<T> extends Element implements Topology<T> {
- private final Topology<T> rt;
-
- public Atom(Topology<T> rt) { this.rt = 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();
+ protected abstract Topology<T> top();
+ public abstract String toString();
+ public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
// 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); }
-
+ 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;
+ }
}