X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FStateNode.java;h=c67b1af021926ae64257e34330b855a7b45790b4;hp=af1a3e9c20f60139e71c856cdfc2a022150eaace;hb=HEAD;hpb=d96df56ee69e62c4d4d6dfe3786ea4853e5120eb;ds=sidebyside

diff --git a/src/edu/berkeley/sbp/StateNode.java b/src/edu/berkeley/sbp/StateNode.java
index af1a3e9..c67b1af 100644
--- a/src/edu/berkeley/sbp/StateNode.java
+++ b/src/edu/berkeley/sbp/StateNode.java
@@ -16,12 +16,14 @@ final class StateNode
     implements Invokable<Pos, ResultNode, Object> {
 
     private final Parser.Table.State state;
-    private  boolean fromEmptyReduction;
 
     /** which GSS.Phase this StateNode belongs to */
-    public Iterator<ResultNode> iterator() { return predecessors.iterator(); }
     public Parser.Table.State state() { return state; }
     public boolean isDoomedState() { return state.doomed; }
+    public boolean hasPathToRoot() {
+        if (state.doomed) return false;
+        return super.hasPathToRoot();
+    }
 
     public void check() {
         if (destroyed) return;
@@ -31,10 +33,10 @@ final class StateNode
         //      - be on the frontier or
         //      - have a non-doomed node closer to the frontier than themself
         if (phase().isFrontier()) dead = false;
-        else for(ResultNode r : successors)
+        else for(ResultNode r : successors())
                  if (state.doomed) { if (r.hasSuccessors()) { dead = false; break; } }
                  else              { if (r.hasNonDoomedSuccessors()) { dead = false; break; } }
-        dead |= predecessors.size()==0;
+        dead |= !hasPredecessors();
         if (!dead) return;
         if (phase() != null && phase().hash != null)
             phase().hash.remove(state, predecessorPhase());
@@ -44,39 +46,36 @@ final class StateNode
     public final void invoke(Pos r, ResultNode only, Object o) {
         boolean emptyProductions = only==null;
         if (emptyProductions != (r.numPops()==0)) return;
-        if (r.numPops()!=0)  reduce(r, r.numPops()-1, phase(), only);
-        else {
+        if (r.numPops()==0) {
             Input.Region region = phase().getLocation().createRegion(phase().getLocation());
             phase().newNodeFromReduction(r.rewrite(region), r, this);
+        } else {
+            // never start reductions at a node that was created via a right-nulled rule
+            if (only.reduction() != null && only.reduction().numPops()==0) return;
+            reduce(r, r.numPops()-1, phase(), only);
         }
     }
 
     private void reduce(Pos r, int pos, GSS.Phase target, ResultNode only) {
-        for(ResultNode res : predecessors)
+        for(ResultNode res : this)
             if (only == null || res == only)
-                for(StateNode pred : res)
-                    reduce2(r, pos, target, pred, res.getForest());
+                for(StateNode pred : res) {
+                    Forest[] holder = r.holder;
+                    Forest old = pos >= holder.length ? null : holder[pos];
+                    if (pos < holder.length) holder[pos] = res.getForest();
+                    if (pos>0)  pred.reduce(r, pos-1, target, null);
+                    else new Reduction(pred, r,
+                                       pred.hasPathToRoot()              
+                                       ? r.rewrite(pred.phase().getLocation().createRegion(target.getLocation()))
+                                       : null,
+                                       target);
+                    if (pos < holder.length) holder[pos] = old;
+                }
     }
 
-    void reduce2(Pos r, int pos, GSS.Phase target, StateNode pred, Forest f) {
-        Forest[] holder = r.holder;
-        Forest old = pos >= holder.length ? null : holder[pos];
-        if (pos < holder.length) holder[pos] = f;
-        if (pos>0)  pred.reduce(r, pos-1, target, null);
-        else {
-            Input.Region region = pred.phase().getLocation().createRegion(target.getLocation());
-            new Reduction(pred, r, r.rewrite(region), target);
-        }
-        if (pos < holder.length) holder[pos] = old;
-    }
-
-    StateNode(GSS.Phase phase, Forest f, Pos reduction, StateNode pred, State state, boolean fromEmptyReduction) {
-        this(phase, new ResultNode(f, reduction, pred), state, fromEmptyReduction);
-    }
-    StateNode(GSS.Phase phase, ResultNode pred, State state, boolean fromEmptyReduction) {
+    StateNode(GSS.Phase phase, ResultNode pred, State state) {
         super(phase, pred.phase());
         this.state = state;
-        this.fromEmptyReduction = fromEmptyReduction;
         if (phase.hash.get(state, pred.phase()) != null) throw new Error("severe problem!");
         phase.hash.put(state, pred.phase(), this);
         addPred(pred);
@@ -86,7 +85,7 @@ final class StateNode
     // Add/Remove Successors/Predecessors //////////////////////////////////////////////////////////////////////////////
 
     public void addPred(Forest f, Pos reduction, StateNode pred) {
-        for(ResultNode r : predecessors)
+        for(ResultNode r : this)
             if (r.predecessorsContains(pred)) {
                 r.merge(f);
                 return;
@@ -95,7 +94,6 @@ final class StateNode
     }
     protected void addPred(ResultNode result) {
         super.addPred(result);
-        if (!this.fromEmptyReduction)
-            state.invokeReductions(phase().getToken(), this, result);
+        state.invokeReductions(phase().getToken(), this, result);
     }
 }