X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=c1642627c0dac9d744973d40a0c904f7369ceea4;hp=474a5421a8e783eca00c22e9a8dbe9d5ab154120;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=4061f053ccd06b1e833c523b26001942e8c5afcd

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 474a542..c164262 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -26,6 +26,8 @@ public class Union extends Element implements Iterable<Sequence> {
     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
@@ -53,14 +55,17 @@ public class Union extends Element implements Iterable<Sequence> {
     }
 
     /** 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 */
@@ -68,19 +73,13 @@ public class Union extends Element implements Iterable<Sequence> {
         add(Sequence.create(e));
     }
 
-
-    // Epsilon Form //////////////////////////////////////////////////////////////////////////////
-
-    // FIXME
-    //private Forest.Many epsilonForm = null;
-    Forest epsilonForm(Input.Region loc) {
-        //if (epsilonForm != null) return epsilonForm;
+    /** the Forest which results from matching this Union against the empty string at region <tt>region</tt> */
+    Forest epsilonForm(Input.Region region, Cache cache) {
+        viewed = true;
         Forest.Many epsilonForm = new Forest.Many();
-        for(Sequence s : this) {
-            // FIXME FIXME FIXME
-            if (new Walk.Cache().possiblyEpsilon(s))
-                epsilonForm.merge(s.epsilonForm(loc));
-        }
+        for(Sequence s : this)
+            if (cache.possiblyEpsilon(s))
+                epsilonForm.merge(s.epsilonForm(region, cache));
         return epsilonForm;
     }
 
@@ -91,7 +90,8 @@ public class Union extends Element implements Iterable<Sequence> {
     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("(");
@@ -102,7 +102,8 @@ public class Union extends Element implements Iterable<Sequence> {
 
     /** 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()) + " = ";