Union: many cleanups

darcs-hash:20070326054612-5007d-14dd73800a517a4e412930f61efa0a3b3daff044.gz

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 94c1fc9..1843a46 100644 (file)
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -54,14 +54,17 @@ 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 */
@@ -72,16 +75,16 @@ public class Union extends Element implements Iterable<Sequence> {
 
     // Epsilon Form //////////////////////////////////////////////////////////////////////////////
 
-    // FIXME
-    //private Forest.Many epsilonForm = null;
+    private Forest.Many epsilonForm = null;
     Forest epsilonForm(Input.Region loc) {
-        //if (epsilonForm != null) return epsilonForm;
+        // FIXME: this is pretty ugly...
+        viewed = true;
+        if (epsilonForm != null) return epsilonForm;
         Forest.Many epsilonForm = new Forest.Many();
-        for(Sequence s : this) {
-            // FIXME FIXME FIXME
-            if (new Walk.Cache().possiblyEpsilon(s))
+        Cache cache = new Cache(null, null);
+        for(Sequence s : this)
+            if (cache.possiblyEpsilon(s))
                 epsilonForm.merge(s.epsilonForm(loc));
-        }
         return epsilonForm;
     }
 
@@ -92,7 +95,8 @@ 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("(");
@@ -103,7 +107,8 @@ 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()) + " = ";