X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=c1642627c0dac9d744973d40a0c904f7369ceea4;hp=70a3e45753a8e4912a2edf343a8131922d5cd592;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=5d18f5606c9296e6b0c5749f05fc68f358ace2f6
diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 70a3e45..c164262 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -1,3 +1,5 @@
+// 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.*;
@@ -7,80 +9,124 @@ import java.util.*;
import java.lang.reflect.*;
import java.lang.ref.*;
-/** an element which can produce one of several alternatives */
+/**
+ * an element which can produce one of several alternatives.
+ *
+ *
+ * Unlike the other Elements, Union is not immutable once
+ * constructed. To simulate this desirable feature, it is immutable
+ * once examined by taking its iterator or calling contains().
+ */
public class Union extends Element implements Iterable {
+ private final String name;
+ private final boolean synthetic;
+ private boolean viewed = false;
+
+ private final List alternatives = new ArrayList();
+
+ 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
* least one Union, every instance of this class must be able to
* display itself in both "long form" (list of the long forms of
- * its alternatives) and "short form" (some abbreviation).
+ * its alternatives) and "short form" (some name).
*
- * @param shortForm the "short form" display; usually
+ * @param shortForm the "short form" display; for display purposes only
* @param synthetic if true, this Union's "long form" is "obvious" and should not be displayed when printing the grammar
*/
- public Union(String shortForm) { this(shortForm, false); }
- public Union(String shortForm, boolean synthetic) {
- this.shortForm = shortForm;
+ public Union(String name, boolean synthetic) {
+ this.name = name;
this.synthetic = synthetic;
}
- /** display form for the Union (ie not including the RHS) */
- final String shortForm;
-
- /** this is just a hint to use when printing out the grammar in visual form */
- final boolean synthetic;
-
- /** the actual alternatives */
- private final List alternatives = new ArrayList();
+ public boolean contains(Sequence s) {
+ viewed = true;
+ return alternatives.contains(s);
+ }
- public Iterator iterator() { return alternatives.iterator(); }
- public boolean contains(Sequence s) { return alternatives.contains(s); }
+ /** iterator over this Union's Sequences */
+ public Iterator iterator() {
+ viewed = true;
+ return alternatives.iterator();
+ }
/** adds an alternative */
- public void add(Sequence s) {
+ public Union add(Sequence s) {
+ if (viewed)
+ 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);
-
- // FIXME: does this make sense?
- for(Sequence n : s.needs) add(n);
- for(Sequence n : s.hates) add(n);
+ return this;
}
- // Epsilon Form //////////////////////////////////////////////////////////////////////////////
-
- // FIXME
- public static Union epsilon = new Union("()");
- static { epsilon.add(Sequence.empty); }
+ /** adds a one-element sequence */
+ public void add(Element e) {
+ add(Sequence.create(e));
+ }
- // FIXME
- private Forest.Ref epsilonForm = null;
- Forest epsilonForm() {
- if (epsilonForm != null) return epsilonForm;
- epsilonForm = new Forest.Ref();
- 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 region */
+ Forest epsilonForm(Input.Region region, Cache cache) {
+ viewed = true;
+ Forest.Many epsilonForm = new Forest.Many();
+ for(Sequence s : this)
+ if (cache.possiblyEpsilon(s))
+ epsilonForm.merge(s.epsilonForm(region, cache));
return epsilonForm;
}
+
// Display //////////////////////////////////////////////////////////////////////////////
- public String toString() { return shortForm; }
+ boolean isSynthetic() { return synthetic; }
+ String getName() { return name==null ? "(anon_union)" : name; }
+
+ public String toString() {
+ // 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("(");
+ bodyToString(sb, "", " | ");
+ sb.append(")");
+ return sb.toString();
+ }
+
+ /** display this union in long/expanded form */
public StringBuffer toString(StringBuffer sb) {
+ // 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()) + " = ";
if (alternatives.size()==0) {
- sb.append(StringUtil.pad(15, shortForm) + " = ");
- } else for(Sequence s : this) {
- sb.append(StringUtil.pad(15, first ? shortForm : "") + (first ? " = " : " | "));
- first = false;
- sb.append(s.toString());
+ sb.append(before);
+ } else {
+ bodyToString(sb,
+ before,
+ "\n" + StringUtil.pad(15, "") + " | ");
sb.append('\n');
}
- sb.append('\n');
return sb;
}
+
+ private void bodyToString(StringBuffer sb, String before, String between) {
+ viewed = true;
+ boolean first = true;
+ for(Sequence s : this) {
+ // FIXME: what to do here about printing out negated sequences?
+ sb.append(first ? before : between);
+ first = false;
+ sb.append(s.toString());
+ }
+ }
}