1 package edu.berkeley.sbp;
2 import edu.berkeley.sbp.util.*;
3 import edu.berkeley.sbp.*;
4 import edu.berkeley.sbp.*;
7 import java.lang.reflect.*;
8 import java.lang.ref.*;
10 /** currently this class exports only static methods to create repetitions; there are no public instance methods or constructors */
11 class Repeat extends Union {
13 public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, Object tag) {
14 this(e, zeroOkay, manyOkay, null, false, tag); }
15 public Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, Object tag) {
16 this(e, zeroOkay, manyOkay, separator, false, tag); }
17 protected Repeat(final Element e, boolean zeroOkay, boolean manyOkay, final Element separator, boolean maximal, Object tag) {
18 super(e+(!manyOkay ? "?" : (zeroOkay ? (maximal ? "**" : "*") : (maximal ? "++" : "+")))+(separator==null?"":("/"+separator)), true);
19 if (zeroOkay && !manyOkay) {
20 add(new Sequence.Constant.Empty());
21 add(new Sequence.Singleton(e));
25 add(new Sequence.RewritingSequence(tag, new Element[] { }, null));
27 add(new Sequence.Singleton(Sequence.many1(e, separator, tag)));
29 add(new Sequence.RewritingSequence(tag, new Element[] { e }, null));
31 add(new Sequence.Unwrap(new Element[] { e, Repeat.this }, tag));
33 add(new Sequence.Unwrap(new Element[] { e, separator, Repeat.this }, tag, new boolean[] { false, true, false }));
37 public static class Maximal extends Repeat {
38 public Maximal(final Element e, boolean zeroOkay, boolean manyOkay, final Atom separator, Object tag) {
39 super(e, zeroOkay, manyOkay, separator, true, tag);
40 if (zeroOkay && separator != null)
41 throw new RuntimeException("cannot create a maximal repetition of zero or more items with a separator (yet): " + this);
42 for(Sequence s : this)
43 s.follow = new Invert(separator);
45 public Maximal(final Atom e, boolean zeroOkay, boolean manyOkay, Object tag) {
46 super(e, zeroOkay, manyOkay, null, true, tag);
47 for(Sequence s : this)
48 s.follow = new Invert(e);
53 /** an atom which tracks the inverse of some other atom */
54 private static class Invert<T extends Input> extends Atom<T> {
55 private final Atom<T> a;
56 public Invert(Atom<T> a) { this.a = a; }
57 public Topology<T> top() { return a.complement(); }
58 public String toString() { return "~"+a; }