rename edu.berkeley.sbp.Cache to Grammar

[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 2c36c8d..968d78f 100644 (file)
--- a/src/edu/berkeley/sbp/Sequence.java
+++ b/src/edu/berkeley/sbp/Sequence.java
@@ -20,7 +20,7 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
     final HashSet<Sequence> needs  = new HashSet<Sequence>();
     final HashSet<Sequence> hates  = new HashSet<Sequence>();
 
-    // FIXME: these are ugly -- migrate into Cache
+    // FIXME: these are ugly -- migrate into Grammar
     HashMap<Sequence,Boolean> canNeed = new HashMap<Sequence,Boolean>();
     HashMap<Sequence,Boolean> canKill = new HashMap<Sequence,Boolean>();
 
@@ -98,17 +98,13 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
     public Iterator<Element> iterator()    { return new ArrayIterator<Element>(elements); }
     protected Sequence(Element[] elements) {
         this.elements = elements;
-        this.firstp = new Position(0);
+        for(int i=0; i<elements.length; i++)
+            if (elements[i]==null)
+                throw new RuntimeException("cannot have nulls in a sequence: " + this);
+        this.firstp = new Position(0, null);
     }
 
-    // DO NOT MESS WITH THE FOLLOWING LINE!!!
-    private Forest.Many epsilonForm = null;
-    Forest epsilonForm(Input.Region loc) {
-        if (epsilonForm!=null) return epsilonForm;
-        epsilonForm = new Forest.Many();
-        epsilonForm.merge(firstp().rewrite(loc, false));
-        return epsilonForm;
-    }
+    abstract Forest epsilonForm(Input.Region loc, Grammar cache);
 
     protected abstract <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p);
 
@@ -119,35 +115,23 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
     class Position implements IntegerMappable {
 
         public int ord = -1;
-        public int compareTo(Position p, Walk.Cache cache) {
-            Position position = this;
-            Position rposition = p;
-            int ret = 0;
-            if (Reduction.canKill(cache, position, rposition) &&
-                Reduction.canKill(cache, rposition, position)) throw new Error();
-            if      (Reduction.canKill(cache, position,   rposition)) ret =  1;
-            else if (Reduction.canKill(cache, rposition, position)) ret = -1;
-            if      (Reduction.canNeed(cache, position,   rposition)) ret =  1;
-            else if (Reduction.canNeed(cache, rposition, position)) ret = -1;
-            return ret;
-        }
 
         private Forest zero = null;
+        /*
         public Forest zero(Input.Region reg) {
             if (zero != null) return zero;
-            if (pos > 0) throw new Error();
+            if (pos > 0) throw new RuntimeException("Position.zero(): pos>0");
             return zero = rewrite(reg);
         }
-
-
+        */
                 final int      pos;
         private final Position next;
         private final Position prev;
                 final Forest[] holder;
         
-        private Position(int pos) {
+        private Position(int pos, Position prev) {
             this.pos      = pos;
-            this.next     = pos==elements.length ? null : new Position(pos+1);
+            this.next     = pos==elements.length ? null : new Position(pos+1, this);
             this.holder   = new Forest[elements.length];
             this.prev     = prev;
         }
@@ -170,17 +154,14 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
 
         // Position /////////////////////////////////////////////////////////////////////////////////
 
-        final <T> Forest<T> rewrite(Input.Region loc) { return rewrite(loc, true); }
-        private final <T> Forest<T> rewrite(Input.Region loc, boolean epsilonCheck) {
-            if (epsilonCheck && this==firstp()) return epsilonForm(loc);
+        final <T> Forest<T> rewrite(Input.Region loc, Grammar cache) {
+            if (this==firstp()) epsilonForm(loc, cache);
             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(loc);
-                if (holder[i]==null) throw new Error("bad " + i);
+                if (holder[i]==null) holder[i] = ((Union)elements[i]).epsilonForm(loc, cache);
+                if (holder[i]==null) throw new Error("bad");
             }
-            Forest<T> ret = Sequence.this.postReduce(loc, holder, this);
-            //for(int k=0; k<pos; k++) holder[k] = null; // to help GC
-            return ret;
+            return Sequence.this.postReduce(loc, holder, this);
         }
 
         public String   toString() {
@@ -238,6 +219,9 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
         public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) {
             return (Forest<T>)Forest.create(loc, result, null, false);
         }
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return Forest.create(loc, result, null, false);
+        }
     }
 
     static class Singleton extends Sequence {
@@ -246,6 +230,9 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
         public Singleton(Element[] e, int idx) { super(e); this.idx = idx; }
         public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) { return args[idx]; }
         Sequence _clone() { return new Singleton(elements,idx); }
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return ((Union)elements[idx]).epsilonForm(loc, cache);
+        }
     }
 
     static class Unwrap extends Sequence {
@@ -264,6 +251,9 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
             for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
             return Forest.create(loc, (T)tag, args2, true);
         }
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return Forest.create(loc, tag, new Forest[0], false);
+        }
     }
 
     static class RewritingSequence extends Sequence {
@@ -283,7 +273,6 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
             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, false);
         }
         public StringBuffer toString(StringBuffer sb, boolean spacing) {
@@ -295,6 +284,9 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
             if (spacing) for(int i=0; i<50-len; i++) sb.append(' ');
             return sb;
         }
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return Forest.create(loc, tag, new Forest[0], false);
+        }
     }
 
 }