X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FSequence.java;h=c41be4ff9d62da6ba0537477b13c3db22aaed42d;hp=3e260f14bbd6500196a197e2afb858bb5bf2d7df;hb=2afdfe14e78fa0597186614937c679a09d74ecdf;hpb=9d727bd14c659cdc6c34153b988e8d3fdb8067f5

diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index 3e260f1..c41be4f 100644
--- 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>();
 
@@ -54,6 +54,11 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
             ? new Unwrap(e, head, drop)
             : new RewritingSequence(head, e, drop);
     }
+    public static Sequence createLeft(Object head, Element[] e, boolean[] drop, boolean foster) {
+        return foster
+            ? new UnwrapLeft(e, head, drop)
+            : new RewritingSequence(head, e, drop);
+    }
 
     /** return a new sequence identical to this one, but with a positive conjunct <tt>s</tt> */
     public Sequence and(Sequence s) {
@@ -104,14 +109,7 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
         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);
 
@@ -124,12 +122,13 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
         public int ord = -1;
 
         private Forest zero = null;
+        /*
         public Forest zero(Input.Region reg) {
             if (zero != null) return zero;
             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;
@@ -160,13 +159,12 @@ 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");
             }
             return Sequence.this.postReduce(loc, holder, this);
         }
@@ -226,6 +224,9 @@ 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 {
@@ -234,6 +235,9 @@ 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 {
@@ -252,6 +256,30 @@ 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 UnwrapLeft extends Sequence {
+        private boolean[] drops;
+        private final Object tag;
+        public UnwrapLeft(Element[] e, Object tag)                  { this(e, tag, null); }
+        public UnwrapLeft(Element[] e, Object tag, boolean[] drops) { super(e); this.drops = drops; this.tag = tag; }
+        Sequence _clone() { return new UnwrapLeft(elements, tag, drops); }
+        public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) {
+            for(int i=0; i<args.length; i++) if (args[i]==null) throw new Error();
+            if (drops==null) return Forest.create(loc, (T)tag, args, false, true);
+            int count = 0;
+            for(int i=0; i<drops.length; i++) if (!drops[i]) count++;
+            Forest<T>[] args2 = new Forest[count];
+            int j = 0;
+            for(int i=0; i<args.length; i++) if (!drops[i]) args2[j++] = args[i];
+            return Forest.create(loc, (T)tag, args2, false, true);
+        }
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return Forest.create(loc, tag, new Forest[0], false);
+        }
     }
 
     static class RewritingSequence extends Sequence {
@@ -282,6 +310,9 @@ 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);
+        }
     }
 
 }