X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FSequence.java;h=5680d6c5f17ca3cb51eb40af4e03c4177adddf2c;hp=8d6709d5f4e1d0164faacedbe0a6c60eb244ad80;hb=2c1c0293545f3d12c23220fd05c663e6aa3f3de1;hpb=e6be1f03f79b16cd410991d7e64cfa7beab6de59
diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index 8d6709d..5680d6c 100644
--- a/src/edu/berkeley/sbp/Sequence.java
+++ b/src/edu/berkeley/sbp/Sequence.java
@@ -8,7 +8,7 @@ import java.lang.reflect.*;
import java.lang.ref.*;
/** juxtaposition; zero or more adjacent Elements; can specify a rewriting */
-public abstract class Sequence extends Element implements Iterable {
+public abstract class Sequence implements Iterable, SequenceOrElement {
protected final Element[] elements;
@@ -32,37 +32,43 @@ public abstract class Sequence extends Element implements Iterable {
return ret;
}
- /** the empty sequence (matches the empty string) */
- static final Sequence empty = new Sequence.Constant.Empty();
- public static Sequence empty() { return empty; }
+ /** create an empty sequence (matches the empty string) */
+ public static Sequence create() { return new Sequence.Constant.Empty(); }
- /** after matching the sequence, do not add anything to the output tree */
- public static Sequence drop(Element[] e) { return new Constant.Drop(e); }
+ /** create a sequence of one element */
+ public static Sequence create(Element e) { return create(new Element[] { e }, 0); }
- /** after matching the sequence, insert a constant into the output tree */
- public static Sequence constant(Element[] e, Object o) { return new Constant(e, o); }
+ /** create a sequence which drops the result of all but one of its element */
+ public static Sequence create(Element[] e, int which) { return new Singleton(e, which); }
- /** after matching the sequence, place the result of the idxth match in the output tree */
- public static Sequence singleton(Element[] e, int idx) { return new Singleton(e, idx); }
- public static Sequence singleton(Element e) { return singleton(new Element[] { e }, 0); }
+ /** create a sequence which always evaluates to a constant result */
+ public static Sequence create(Element[] e, Object result) { return new Constant(e, result); }
/**
- * after matching the sequence, create the specified output tree
- * @param tag the tag for the output tree
- * @param e the elements to match
- * @param drops only elements of e whose corresponding boolean in drops
- * is false will be included in the output tree
+ * create a sequence (general form)
+ * @param head the head of the output tree
+ * @param e the elements to match
+ * @param drop only elements of e whose corresponding boolean in drops
+ * is false will be included in the output tree
+ * @param foster if true, all children of the last child (ie
+ * grandchildren) are promoted to children of this
+ * node; this is very useful for matching repetitions
**/
- public static Sequence rewritingSequence(Object tag, Element[] e, boolean[] drops) {
- return new RewritingSequence(tag, e, drops); }
-
- public static Sequence regionRewritingSequence(Functor tagfunctor, Element[] e, boolean[] drops) {
- return new RegionRewritingSequence(tagfunctor, e, drops); }
+ public static Sequence create(Object head, Element[] e, boolean[] drop, boolean foster) {
+ return foster
+ ? new Unwrap(e, head, drop)
+ : new RewritingSequence(head, e, drop);
+ }
////////////////////////////////////////////////////////////////////////////////
+ /** return a new sequence identical to this one, but with a positive conjunct s */
public Sequence and(Sequence s) { Sequence ret = dup(); ret.needs.add(s); return ret; }
- public Sequence not(Sequence s) { Sequence ret = dup(); ret.hates.add(s); s.hated.add(ret); return ret; }
+
+ /** return a new sequence identical to this one, but with a negative conjunct s */
+ public Sequence andnot(Sequence s) { Sequence ret = dup(); ret.hates.add(s); s.hated.add(ret); return ret; }
+
+ /** return a new sequence identical to this one, but with a follow-set restricted to a */
public Sequence followedBy(Atom a) { Sequence ret = dup(); ret.follow = a; return ret; }
Iterable needs() { return needs; }
@@ -170,6 +176,14 @@ public abstract class Sequence extends Element implements Iterable {
sb.append("-> ");
sb.append(follow);
}
+ for(Sequence s : needs) {
+ sb.append("& ");
+ sb.append(s);
+ }
+ for(Sequence s : hates) {
+ sb.append("&~ ");
+ sb.append(s);
+ }
return sb;
}
@@ -200,7 +214,6 @@ public abstract class Sequence extends Element implements Iterable {
Sequence _clone() { return new Singleton(elements,idx); }
}
- public static Sequence unwrap(Element[] e, Object tag, boolean[] drops) { return new Unwrap(e, tag, drops); }
static class Unwrap extends Sequence {
private boolean[] drops;
private final Object tag;