X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FForest.java;h=1730f607eba82daeb513f88053b53d08137a33e2;hp=1c8fbc5b6f8290bb0c6540a37fd2925900e7b89a;hb=0ddfec9ac2783f59115205dc0f3806137265c59c;hpb=f1dba2b015c3da04fc2fab45604da2e6c9ae0a1d

diff --git a/src/edu/berkeley/sbp/Forest.java b/src/edu/berkeley/sbp/Forest.java
index 1c8fbc5..1730f60 100644
--- a/src/edu/berkeley/sbp/Forest.java
+++ b/src/edu/berkeley/sbp/Forest.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.*;
 import edu.berkeley.sbp.Sequence.Position;
@@ -7,73 +9,82 @@ import java.util.*;
 import java.lang.reflect.*;
 
 /**
+ *   <font color=blue>
  *   An efficient representation of a collection of trees (Tomita's
  *   shared packed parse forest).
+ *   </font>
  */
-public abstract class Forest<T> implements GraphViz.ToGraphViz {
+public abstract class Forest<NodeType> implements GraphViz.ToGraphViz {
 
     /** assume that this forest contains exactly one tree and return it; otherwise throw an exception */
-    public abstract Tree<T> expand1() throws Ambiguous;
+    public abstract Tree<NodeType> expand1() throws Ambiguous;
 
     /** expand this forest into a set of trees */
-    public void expand(HashSet<Tree<T>> ht) { expand(ht, new HashSet<Forest<T>>(), null); }
+    public void expand(HashSet<Tree<NodeType>> ht) { expand(ht, new HashSet<Forest<NodeType>>(), null); }
 
-    /** create a new forest */
-    public static <T> Forest<T> create(Input.Region loc, T head, Forest<T>[] children, boolean unwrap) {
-        return new One<T>(loc, head, children, unwrap);
+    static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
+        if (loc == null) throw new RuntimeException("invoked Forest.create(null,,,,) -- this should never happen");
+        return new One<NodeType>(loc, head, children, lift);
     }
 
+    /** create a new forest */
+    public static <NodeType> Forest<NodeType> create(Input.Region loc, NodeType head, Forest<NodeType>[] children) {
+        return Forest.create(loc, head, children, false); }
+
     // Package-Private //////////////////////////////////////////////////////////////////////////////
 
-    abstract void expand(HashSet<Tree<T>> ht, HashSet<Forest<T>> ignore, Tree<T> bogus);
-    abstract void gather(HashSet<Forest<T>> ignore);
+    abstract void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus);
+    abstract void gather(HashSet<Forest<NodeType>> ignore);
+    abstract void edges(GraphViz.Node n);
     boolean ambiguous() { return false; }
-
-    public abstract void edges(GraphViz.Node n);
-
+    
+    abstract Input.Region getRegion();
 
     // One //////////////////////////////////////////////////////////////////////////////
 
     /** A "single" forest with a head and child subforests */    
-    private static class One<T> extends Forest<T> {
+    private static class One<NodeType> extends Forest<NodeType> {
 
         private final Input.Region      location;
-        private final T                 head;
-        private final Forest<T>[]       children;
+        private final NodeType                head;
+        private final Forest<NodeType>[]       children;
 
         /** if true, the last child's children are considered children of this node */
-        private final boolean           unwrap;
+        private final boolean           lift;
 
-        private One(Input.Region loc, T head, Forest<T>[] children, boolean unwrap) {
+        Input.Region getRegion() { return location; }
+
+        private One(Input.Region loc, NodeType head, Forest<NodeType>[] children, boolean lift) {
             this.location = loc;
             this.head = head;
+            if (head==null) throw new RuntimeException("invoked Forest.create(,null,,,) -- this should never happen");
             this.children = children==null ? emptyForestArray : new Forest[children.length];
             if (children != null) System.arraycopy(children, 0, this.children, 0, children.length);
             if (children != null) for(int i=0; i<children.length; i++) if (children[i]==null) throw new Error(i+"");
-            this.unwrap = unwrap;
+            this.lift = lift;
         }
 
-        public Tree<T> expand1() throws Ambiguous {
-            Tree<T>[] ret = new Tree[children.length];
+        public Tree<NodeType> expand1() throws Ambiguous {
+            Tree<NodeType>[] ret = new Tree[children.length];
             for(int i=0; i<children.length; i++) ret[i] = children[i].expand1();
-            return new Tree<T>(location, head, ret, unwrap);
+            return new Tree<NodeType>(location, head, ret, lift);
         }
 
-        void gather(HashSet<Forest<T>> hf) {
+        void gather(HashSet<Forest<NodeType>> hf) {
             hf.add(this);
-            for(Forest<T> f : children) f.gather(hf);
+            for(Forest<NodeType> f : children) f.gather(hf);
         }
-        void expand(HashSet<Tree<T>> ht, HashSet<Forest<T>> ignore, Tree<T> bogus) {
+        void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
             if (ignore.contains(this)) { ht.add(bogus); return; }
             expand(0, new Tree[children.length], ht, ignore, bogus);
         }
-        private void expand(final int i, Tree<T>[] ta, HashSet<Tree<T>> ht, HashSet<Forest<T>> ignore, Tree<T> bogus) {
+        private void expand(final int i, Tree<NodeType>[] ta, HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
             if (i==children.length) {
-                ht.add(new Tree<T>(location, head, ta, unwrap));
+                ht.add(new Tree<NodeType>(location, head, ta, lift));
             } else {
-                HashSet<Tree<T>> ht2 = new HashSet<Tree<T>>();
+                HashSet<Tree<NodeType>> ht2 = new HashSet<Tree<NodeType>>();
                 children[i].expand(ht2, ignore, bogus);
-                for(Tree<T> tc : ht2) {
+                for(Tree<NodeType> tc : ht2) {
                     ta[i] = tc;
                     expand(i+1, ta, ht, ignore, bogus);
                     ta[i] = null;
@@ -98,7 +109,7 @@ public abstract class Forest<T> implements GraphViz.ToGraphViz {
             if (edges) return;
             edges = true;
             for(int i=0; i<children.length; i++) {
-                if (i==children.length-1 && unwrap && !children[i].ambiguous()) {
+                if (i==children.length-1 && lift && !children[i].ambiguous()) {
                     children[i].edges(n);
                 } else {
                     n.edge(children[i], null);
@@ -117,26 +128,27 @@ public abstract class Forest<T> implements GraphViz.ToGraphViz {
     // Many //////////////////////////////////////////////////////////////////////////////
 
     /** An "ambiguity node"; this is immutable once it has been "looked at" */
-    static class Many<T> extends Forest<T> {
+    static class Many<NodeType> extends Forest<NodeType> {
 
-        HashSet<GSS.Phase.Node> parents = new HashSet<GSS.Phase.Node>();
-        private FastSet<Forest<T>> hp = new FastSet<Forest<T>>();
+        private FastSet<Forest<NodeType>> hp = new FastSet<Forest<NodeType>>();
         private boolean touched = false;
 
         public Many() { }
 
-        public Tree<T> expand1() throws Ambiguous {
+        Input.Region getRegion() { return hp.iterator().next().getRegion(); } // all should be identical
+
+        public Tree<NodeType> expand1() throws Ambiguous {
             touched();
             if (hp.size() > 1) {
-                HashSet<Forest<T>> hf0 = new HashSet<Forest<T>>();
-                Iterator<Forest<T>> ih = hp.iterator();
+                HashSet<Forest<NodeType>> hf0 = new HashSet<Forest<NodeType>>();
+                Iterator<Forest<NodeType>> ih = hp.iterator();
                 ih.next().gather(hf0);
-                for(Forest<T> f : hp) {
-                    HashSet<Forest<T>> hf1 = new HashSet<Forest<T>>();
+                for(Forest<NodeType> f : hp) {
+                    HashSet<Forest<NodeType>> hf1 = new HashSet<Forest<NodeType>>();
                     f.gather(hf1);
                     hf0.retainAll(hf1);
                 }
-                HashSet<Tree<T>> ht = new HashSet<Tree<T>>();
+                HashSet<Tree<NodeType>> ht = new HashSet<Tree<NodeType>>();
                 expand(ht, hf0, new Tree(null, "*"));
                 throw new Ambiguous((Forest<?>)this,
                                     (HashSet<Tree<?>>)(Object)ht);
@@ -144,20 +156,28 @@ public abstract class Forest<T> implements GraphViz.ToGraphViz {
             return hp.iterator().next().expand1();
         }
         
-        void gather(HashSet<Forest<T>> ht) {
+        void gather(HashSet<Forest<NodeType>> ht) {
             touched();
+
+            // FIXME: do something more sensible here
+            if (ht.contains(this)) {
+                System.err.println("WARNING: grammar produced a circular forest\n" + this);
+                //throw new Error("grammar produced a circular forest:\n" + this);
+                return;
+            }
+
             ht.add(this);
-            for(Forest<T> f : hp) f.gather(ht);
+            for(Forest<NodeType> f : hp) f.gather(ht);
         }
 
         private void touched() {
             if (touched) return;
             touched = true;
             /*
-            FastSet<Forest<T>> f2 = new FastSet<Forest<T>>();
+            FastSet<Forest<NodeType>> f2 = new FastSet<Forest<NodeType>>();
             for(Forest f : hp)
                 if (f instanceof Forest.One) f2.add(f);
-                else for(Forest ff : ((Forest.Many<T>)f))
+                else for(Forest ff : ((Forest.Many<NodeType>)f))
                     f2.add(ff);
             hp = f2;
             */
@@ -178,10 +198,10 @@ public abstract class Forest<T> implements GraphViz.ToGraphViz {
             return true;
         }
 
-        void expand(HashSet<Tree<T>> ht, HashSet<Forest<T>> ignore, Tree<T> bogus) {
+        void expand(HashSet<Tree<NodeType>> ht, HashSet<Forest<NodeType>> ignore, Tree<NodeType> bogus) {
             touched();
             if (ignore.contains(this)) { ht.add(bogus); return; }
-            for (Forest<T> f : hp) f.expand(ht, ignore, bogus);
+            for (Forest<NodeType> f : hp) f.expand(ht, ignore, bogus);
         }