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> {
protected abstract Topology<T> top();
public abstract String toString();
-
- public Topology toAtom() { return this; }
+ public StringBuffer toString(StringBuffer sb) { sb.append(this); return sb; }
// Topology Thunks //////////////////////////////////////////////////////////////////////////////
// Subclasses //////////////////////////////////////////////////////////////////////////////
- public static class Infer<T extends Token> extends Atom<T> {
+ /** an atom which tracks the possible tokenset of some element, provided that element can only match single-token sequences */
+ public static class Infer<T extends Input> extends Atom<T> {
private final Element e;
public Infer(Element e) { this.e = e; }
- public Topology<T> top() { return (Topology<T>)e.toAtom(); }
- public String toString() { return e.toString(); /* FIXME should be toAtom() */ }
+ public Topology<T> top() { return (Topology<T>)toAtom(e); }
+ public String toString() { return e.toString(); }
}
- public static class Invert<T extends Token> extends Atom<T> {
+ /** an atom which tracks the inverse of some other atom */
+ public static class Invert<T extends Input> extends Atom<T> {
private final Atom<T> a;
public Invert(Atom<T> a) { this.a = a; }
public Topology<T> top() { return ((Topology<T>)a.top()).complement(); }
public String toString() { return "~"+a; }
}
-
- public static class Hack<T extends Token> extends Atom<T> {
- private final Atom<T> a;
- static final Topology leftright =
- edu.berkeley.sbp.misc.CharToken.rightBrace.union(edu.berkeley.sbp.misc.CharToken.leftBrace);
- public Hack(Atom<T> a) { this.a = a; }
- public Topology<T> top() { return ((Topology<T>)a.top()).minus(leftright); }
- public String toString() { return "~"+a; }
+
+ 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;
}
-
}