it all works

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

diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index d252604..83d9b6f 100644 (file)
--- a/src/edu/berkeley/sbp/Sequence.java
+++ b/src/edu/berkeley/sbp/Sequence.java
@@ -35,7 +35,8 @@ public abstract class Sequence extends Element implements Iterable<Element> {
 
     ////////////////////////////////////////////////////////////////////////////////
 
 
     ////////////////////////////////////////////////////////////////////////////////
 

-    public Topology noFollow() { return null; }
+    public Element noFollow = null;
+    public final Topology noFollow() { return noFollow==null ? null : noFollow.toAtom(); }

 
     Topology toAtom() {
         if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this);
 
     Topology toAtom() {
         if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this);

@@ -55,15 +56,21 @@ public abstract class Sequence extends Element implements Iterable<Element> {
     protected Sequence(Element[] elements, HashSet<Sequence> and, HashSet<Sequence> not) {
         this.needs = and==null ? new HashSet<Sequence>() : and;
         this.hates = not==null ? new HashSet<Sequence>() : not;
     protected Sequence(Element[] elements, HashSet<Sequence> and, HashSet<Sequence> not) {
         this.needs = and==null ? new HashSet<Sequence>() : and;
         this.hates = not==null ? new HashSet<Sequence>() : not;

-        //for(Sequence s : needs) s.lame = true;
-        //for(Sequence s : hates) s.lame = true;

         this.elements = elements;
         this.firstp = new Position(0);
     }
 
         this.elements = elements;
         this.firstp = new Position(0);
     }
 

-    void reachable(HashSet<Position> h) { firstp().reachable(h); }
-
-    Forest epsilonForm() { return firstp().rewrite(null); }
+    // DO NOT MESS WITH THE FOLLOWING LINE!!!
+    private Forest.Ref epsilonForm = null;
+    private boolean eps = false;
+    Forest epsilonForm() {
+        if (epsilonForm==null) {
+            epsilonForm = new Forest.Ref();
+            Forest fo = firstp().rewrite(null);
+            epsilonForm.merge(fo);
+        }
+        return epsilonForm;
+    }

 
     protected abstract <T> Forest<T> postReduce(Token.Location loc, Forest<T>[] args);
 
 
     protected abstract <T> Forest<T> postReduce(Token.Location loc, Forest<T>[] args);
 

@@ -73,12 +80,6 @@ public abstract class Sequence extends Element implements Iterable<Element> {
     /** the imaginary position before or after an element of a sequence; corresponds to an "LR item" */
     public class Position {
 
     /** the imaginary position before or after an element of a sequence; corresponds to an "LR item" */
     public class Position {
 

-        void reachable(HashSet<Position> h) {
-            if (h.contains(this)) return;
-            h.add(this);
-            if (element() != null) element().reachable(h);
-        }
-

                 final int      pos;
         private final Position next;
                 final Forest[] holder;
                 final int      pos;
         private final Position next;
                 final Forest[] holder;

@@ -110,10 +111,17 @@ public abstract class Sequence extends Element implements Iterable<Element> {
 
         // Reduction /////////////////////////////////////////////////////////////////////////////////
 
 
         // Reduction /////////////////////////////////////////////////////////////////////////////////
 

-        <T> Forest<T> rewrite(Token.Location loc) {
-            for(int i=pos; i<elements.length; i++) if (holder[i]==null) holder[i] = elements[i].epsilonForm();
+        final <T> Forest<T> rewrite(Token.Location loc) {
+            if (this==firstp() && eps) return epsilonForm;
+            eps = true;
+            for(int i=0; i<pos; i++) if (holder[i]==null) throw new Error("realbad " + i);
+            for(int i=pos; i<elements.length; i++) {
+                if (holder[i]==null) holder[i] = elements[i].epsilonForm();
+                if (holder[i]==null) throw new Error("bad " + i);
+            }

             Forest<T> ret = Sequence.this.postReduce(loc, holder);
             for(int k=0; k<pos; k++) holder[k] = null; // to help GC
             Forest<T> ret = Sequence.this.postReduce(loc, holder);
             for(int k=0; k<pos; k++) holder[k] = null; // to help GC

+            if (this==firstp()) { if (epsilonForm==null) epsilonForm=new Forest.Ref(); epsilonForm.merge(ret); return epsilonForm; }

             return ret;
         }
 
             return ret;
         }
 

@@ -174,6 +182,7 @@ public abstract class Sequence extends Element implements Iterable<Element> {
         public Unwrap(Element[] e, HashSet<Sequence> and, HashSet<Sequence> not)                  { super(e, and, not); this.drops = null; }
         public Unwrap(Element[] e, boolean[] drops, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.drops = drops; }
         public <T> Forest<T> postReduce(Token.Location loc, Forest<T>[] args) {
         public Unwrap(Element[] e, HashSet<Sequence> and, HashSet<Sequence> not)                  { super(e, and, not); this.drops = null; }
         public Unwrap(Element[] e, boolean[] drops, HashSet<Sequence> and, HashSet<Sequence> not) { super(e, and, not); this.drops = drops; }
         public <T> Forest<T> postReduce(Token.Location loc, Forest<T>[] args) {

+            for(int i=0; i<args.length; i++) if (args[i]==null) throw new Error();

             if (drops==null) return Forest.create(loc, null, args, this, true, false);
             int count = 0;
             for(int i=0; i<drops.length; i++) if (!drops[i]) count++;
             if (drops==null) return Forest.create(loc, null, args, this, true, false);
             int count = 0;
             for(int i=0; i<drops.length; i++) if (!drops[i]) count++;

@@ -199,6 +208,7 @@ public abstract class Sequence extends Element implements Iterable<Element> {
             Forest<T>[] args2 = new Forest[count];
             int j = 0;
             for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
             Forest<T>[] args2 = new Forest[count];
             int j = 0;
             for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];

+            //System.out.println("reduce \""+tag+"\"");

             return Forest.create(loc, (T)tag, args2, this, false, false);
         }
         public StringBuffer toString(StringBuffer sb, boolean spacing) {
             return Forest.create(loc, (T)tag, args2, this, false, false);
         }
         public StringBuffer toString(StringBuffer sb, boolean spacing) {