checkpoint

[sbp.git] / src / edu / berkeley / sbp / Forest.java

diff --git a/src/edu/berkeley/sbp/Forest.java b/src/edu/berkeley/sbp/Forest.java
index 475b300..ceb67eb 100644 (file)
--- a/src/edu/berkeley/sbp/Forest.java
+++ b/src/edu/berkeley/sbp/Forest.java
@@ -11,19 +11,26 @@ public abstract class Forest<T> /*extends PrintableTree<Forest.MyBody<T>>*/ impl
 
     /** assume that this forest contains exactly one tree and return it; otherwise throw an exception */
     public final Tree<T> expand1() throws Ambiguous, ParseFailed {
-        Iterator<Tree<T>> it = expand(true).iterator();
-        if (!it.hasNext()) throw new ParseFailed();
-        return it.next();
+        try {
+            Iterator<Tree<T>> it = expand(true).iterator();
+            if (!it.hasNext()) throw new ParseFailed();
+            return it.next();
+        } catch (InnerAmbiguous ia) { throw new Ambiguous(ia.f); }
     }
 
     /** expand this forest into a set of trees */
     public HashSet<Tree<T>> expand(boolean toss) {
         final HashSetTreeConsumer<T> ret = new HashSetTreeConsumer<T>();
         visit(new TreeMaker2<T>(toss, ret), null, null);
-        if (toss && ret.size() > 1) throw new Ambiguous(this);
+        if (toss && ret.size() > 1) throw new InnerAmbiguous(this);
         return ret;
     }
 
+    private static class InnerAmbiguous extends RuntimeException {
+        public final Forest<?> f;
+        public InnerAmbiguous(Forest<?> f) { this.f = f; }
+    }
+
     public static interface TreeConsumer<T> {
         public void addTree(Tree<T> t);
     }
@@ -83,10 +90,10 @@ public abstract class Forest<T> /*extends PrintableTree<Forest.MyBody<T>>*/ impl
             } else {
                 tokens[i].visit(new TreeMaker<T>(h.toss) {
                     public void start(T head, Input.Location loc) { }
-                    public void child(Tree<T> t) { toks.add(t); }
+                    public void addTree(Tree<T> t) { toks.add(t); }
                     public void finish(T head, Input.Location loc) {
                         int old = h.toks.size();
-                        h.child(new Tree<T>(loc, head, toks.toArray(tree_hint)));
+                        h.addTree(new Tree<T>(loc, head, toks.toArray(tree_hint)));
                         expand(i+1, h);
                         while(h.toks.size() > old) h.toks.remove(h.toks.size()-1);
                     }
@@ -127,16 +134,16 @@ public abstract class Forest<T> /*extends PrintableTree<Forest.MyBody<T>>*/ impl
         public TreeMaker2(boolean toss, TreeConsumer<T> tc) { super(toss); this.tc = tc; }
         public void finish(T head, Input.Location loc) { tc.addTree(new Tree<T>(loc, head, toks.toArray(tree_hint)));; }
         public void start(T head, Input.Location loc) { }
-        public void child(Tree<T> t) { toks.add(t); }
+        public void addTree(Tree<T> t) { toks.add(t); }
     }
-    private static abstract class TreeMaker<T> implements Invokable<Forest.Body<T>,Boolean,Integer> {
+    private static abstract class TreeMaker<T> implements Invokable<Forest.Body<T>,Boolean,Integer>, TreeConsumer<T> {
         public ArrayList<Tree<T>> toks = new ArrayList<Tree<T>>();
         private boolean toss;
         protected T head;
         public TreeMaker(boolean toss) { this.toss = toss; }
         public abstract void start(T head, Input.Location loc);
         public abstract void finish(T head, Input.Location loc);
-        public abstract void child(Tree<T> t);
+        public abstract void addTree(Tree<T> t);
         public void invoke(Forest.Body<T> bod, Boolean o, Integer i) {
             if (i==null) {
                 ArrayList<Tree<T>> toks = this.toks;