+// Copyright 2006-2007 all rights reserved; see LICENSE file for BSD-style license
+
package edu.berkeley.sbp;
import edu.berkeley.sbp.util.*;
import edu.berkeley.sbp.*;
*/
public class Union extends Element implements Iterable<Sequence> {
- private final String name;
+ private final String name;
private final boolean synthetic;
private boolean viewed = false;
private final List<Sequence> alternatives = new ArrayList<Sequence>();
public Union(String name) { this(name, false); }
+ public Union(String name, Sequence s) { this(name, s, false); }
+ public Union(String name, Sequence s, boolean synthetic) { this(name, synthetic); add(s); }
/**
* Since every cycle in a non-degenerate grammar contains at
}
/** adds an alternative */
- public void add(Sequence s) {
- /*
- FIXME
+ public Union add(Sequence s) {
if (viewed)
- throw new RuntimeException("attempt to add a Sequence to a Union that has already been examined:\n "+this);
- */
- if (alternatives.contains(s)) return;
+ throw new RuntimeException("once Union.contains() or Union.iterator() has been invoked, "+
+ "you may not add any more Sequences to it\n "+
+ " union in question: " + this);
+ if (s.needed_or_hated)
+ throw new RuntimeException("you may not add a conjunct directly to a Union");
+ s.in_a_union = true;
+ if (alternatives.contains(s)) return this;
alternatives.add(s);
+ return this;
}
/** adds a one-element sequence */
add(Sequence.create(e));
}
-
- // Epsilon Form //////////////////////////////////////////////////////////////////////////////
-
- // FIXME
- private Forest.Many epsilonForm = null;
- Forest epsilonForm() {
- if (epsilonForm != null) return epsilonForm;
- epsilonForm = new Forest.Many();
- for(Sequence s : this) {
- // FIXME FIXME FIXME
- if (new Walk.Cache().possiblyEpsilon(s))
- epsilonForm.merge(s.epsilonForm());
- }
+ /** the Forest which results from matching this Union against the empty string at region <tt>region</tt> */
+ Forest epsilonForm(Input.Region region) {
+ viewed = true;
+ Forest.Many epsilonForm = new Forest.Many();
+ for(Sequence s : this)
+ if (Element.possiblyEpsilon(s))
+ epsilonForm.merge(s.epsilonForm(region));
return epsilonForm;
}
// Display //////////////////////////////////////////////////////////////////////////////
- public String getName() {
- if (name != null) return name;
- return "(anon_union)";
- }
+ boolean isSynthetic() { return synthetic; }
+ String getName() { return name==null ? "(anon_union)" : name; }
+
public String toString() {
- viewed = true;
+ // technically this should be turned on, but we don't make a big deal
+ //viewed = true;
if (name != null) return name;
StringBuffer sb = new StringBuffer();
sb.append("(");
/** display this union in long/expanded form */
public StringBuffer toString(StringBuffer sb) {
- viewed = true;
+ // technically this should be turned on, but we don't make a big deal
+ //viewed = true;
if (synthetic) return sb;
boolean first = true;
String before = StringUtil.pad(15, getName()) + " = ";