+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
package edu.berkeley.sbp;
import edu.berkeley.sbp.util.*;
import edu.berkeley.sbp.*;
import java.lang.ref.*;
/** <font color=green>juxtaposition; zero or more adjacent Elements; can specify a rewriting</font> */
-public abstract class Sequence extends Element implements Iterable<Element> {
+public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
protected final Element[] elements;
return ret;
}
- /** the empty sequence (matches the empty string) */
- public static Sequence newEmptySequence() { return new Sequence.Constant.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 newDropSequence(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 newConstantSequence(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 <tt>idx</tt>th match in the output tree */
- public static Sequence newSingletonSequence(Element[] e, int idx) { return new Singleton(e, idx); }
- public static Sequence newSingletonSequence(Element e) { return newSingletonSequence(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 <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
- * is <i>false</i> 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 <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
+ * is <i>false</i> 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 newRewritingSequence(Object tag, Element[] e, boolean[] drops) {
- return new RewritingSequence(tag, e, drops); }
-
- public static Sequence newUnwrapSequence(Element[] e, Object tag, boolean[] drops) { return new Unwrap(e, tag, 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);
+ }
////////////////////////////////////////////////////////////////////////////////
public Sequence and(Sequence s) { Sequence ret = dup(); ret.needs.add(s); return ret; }
/** return a new sequence identical to this one, but with a negative conjunct <tt>s</tt> */
- public Sequence not(Sequence s) { Sequence ret = dup(); ret.hates.add(s); s.hated.add(ret); return ret; }
+ 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 <tt>a</tt> */
public Sequence followedBy(Atom a) { Sequence ret = dup(); ret.follow = a; return ret; }
// DO NOT MESS WITH THE FOLLOWING LINE!!!
private Forest.Many epsilonForm = null;
- Forest epsilonForm() {
+ Forest epsilonForm(Input.Region loc) {
if (epsilonForm!=null) return epsilonForm;
epsilonForm = new Forest.Many();
- epsilonForm.merge(firstp().rewrite(null, false));
+ epsilonForm.merge(firstp().rewrite(loc, false));
return epsilonForm;
}
class Position implements IntegerMappable {
private Forest zero = null;
- public Forest zero() {
+ public Forest zero(Input.Region reg) {
if (zero != null) return zero;
if (pos > 0) throw new Error();
- return zero = rewrite(null);
+ return zero = rewrite(reg);
}
final <T> Forest<T> rewrite(Input.Region loc) { return rewrite(loc, true); }
private final <T> Forest<T> rewrite(Input.Region loc, boolean epsilonCheck) {
- if (epsilonCheck && this==firstp()) return epsilonForm();
+ if (epsilonCheck && this==firstp()) return epsilonForm(loc);
for(int i=0; i<pos; i++) if (holder[i]==null) throw new Error("realbad " + i);
for(int i=pos; i<elements.length; i++) {
- if (holder[i]==null) holder[i] = elements[i].epsilonForm();
+ if (holder[i]==null) holder[i] = elements[i].epsilonForm(loc);
if (holder[i]==null) throw new Error("bad " + i);
}
Forest<T> ret = Sequence.this.postReduce(loc, holder, this);
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;
}