import java.lang.ref.*;
/** currently this class exports only static methods to create repetitions; there are no public instance methods or constructors */
-/* FIXME make private again */ public class Repeat extends Union {
+class Repeat extends Union {
- public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal) {
- this(e, zeroOkay, manyOkay, separator, maximal, null); }
- Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal, Object tag) {
+ public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, Object tag) {
+ this(e, zeroOkay, manyOkay, null, false, tag); }
+ public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, Object tag) {
+ this(e, zeroOkay, manyOkay, separator, false, tag); }
+ protected Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal, Object tag) {
super(e+(!manyOkay ? "?" : (zeroOkay ? (maximal ? "**" : "*") : (maximal ? "++" : "+")))+(separator==null?"":("/"+separator)), true);
- if (maximal && zeroOkay && separator != null)
- throw new RuntimeException("cannot create a maximal repetition of zero or more items with a separator (yet): " + this);
- if (zeroOkay) {
+ if (zeroOkay && !manyOkay) {
add(new Sequence.Constant.Empty());
- if (manyOkay) add(new Sequence.Singleton(Sequence.many1(e, separator)));
- else add(new Sequence.Singleton(e));
+ add(new Sequence.Singleton(e));
+ return;
+ }
+ if (zeroOkay) {
+ add(new Sequence.RewritingSequence(tag, new Element[] { }, null));
+ //add(new Sequence.Constant.Empty());
+ // FUGLY
+ add(new Sequence.Singleton(Sequence.many1(e, separator, tag)));
} else {
add(new Sequence.RewritingSequence(tag, new Element[] { e }, null));
if (separator==null)
else
add(new Sequence.Unwrap(new Element[] { e, separator, Repeat.this }, tag, new boolean[] { false, true, false }));
}
- // FIXME: hack!
- if (maximal)
+ }
+
+ public static class Maximal extends Repeat {
+ public Maximal(final Element e, boolean zeroOkay, boolean manyOkay, final Atom separator, Object tag) {
+ super(e, zeroOkay, manyOkay, separator, true, tag);
+ if (zeroOkay && separator != null)
+ throw new RuntimeException("cannot create a maximal repetition of zero or more items with a separator (yet): " + this);
for(Sequence s : this)
- s.follow = new edu.berkeley.sbp.misc.MetaGrammar.Invert(new edu.berkeley.sbp.misc.MetaGrammar.Infer(separator==null ? e : separator));
+ s.follow = new Invert(separator);
+ }
+ public Maximal(final Atom e, boolean zeroOkay, boolean manyOkay, Object tag) {
+ super(e, zeroOkay, manyOkay, null, true, tag);
+ for(Sequence s : this)
+ s.follow = new Invert(e);
+ }
+ }
+
+
+ /** an atom which tracks the inverse of some other atom */
+ private 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 a.complement(); }
+ public String toString() { return "~"+a; }
}
}