X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FSequence.java;h=1c76aefadda764a09bf478877d764ecb108c0675;hp=2c36c8db00c2dd2917eaf25e8e7e3e072a7f4b31;hb=584cef55d8811e3215858fde22e708d2a3d1cf70;hpb=a4cd33f348d3802ed746e517c23205958a4ceeb4

diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index 2c36c8d..1c76aef 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>();
 
@@ -34,10 +34,18 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
     public static Sequence create(Element e) { return create(new Element[] { e }, 0); }
 
     /** create a sequence which drops the result of all but one of its element */
-    public static Sequence create(Element[] e, int which) { return new Singleton(e, which); }
+    public static Sequence create(Element[] e, int which) {
+        return new Singleton(e, which); }
 
     /** create a sequence which always evaluates to a constant result  */
-    public static Sequence create(Element[] e, Object result) { return new Constant(e, result); }
+    public static Sequence create(Object result, Element[] e) {
+        return new RewritingSequence(result, e, trues(e.length)); }
+
+    private static boolean[] trues(int length) {
+        boolean[] ret = new boolean[length];
+        for(int i=0; i<ret.length; i++) ret[i] = true;
+        return ret;
+    }
 
     /**
      *  create a sequence (general form)
@@ -45,14 +53,13 @@ public abstract class Sequence implements Iterable<Element>, SequenceOrElement {
      *  @param e      the elements to match
      *  @param drop   only elements of <tt>e</tt> whose corresponding <tt>boolean</tt> in <tt>drops</tt>
      *                is <i>false</i> will be included in the output tree
-     *  @param foster if true, all children of the last child (ie
-     *                grandchildren) are promoted to children of this
-     *                node; this is very useful for matching repetitions
+     *  @param lifts  which (if any) child trees to lift
      **/
-    public static Sequence create(Object head, Element[] e, boolean[] drop, boolean foster) {
-        return foster
-            ? new Unwrap(e, head, drop)
-            : new RewritingSequence(head, e, drop);
+    public static Sequence create(Object head, Element[] e, boolean[] drop) {
+        return create(head, e, drop, new boolean[e.length]); }
+    public static Sequence create(Object head, Element[] e, boolean[] drop, boolean[] lifts) {
+        if (lifts==null) lifts = new boolean[e.length];
+        return new RewritingSequence(head, e, drop, lifts);
     }
 
     /** return a new sequence identical to this one, but with a positive conjunct <tt>s</tt> */
@@ -98,17 +105,13 @@ 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 +122,23 @@ 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 +161,14 @@ 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 +226,9 @@ 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 {
@@ -246,45 +237,36 @@ 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); }
-    }
-
-    static class Unwrap extends Sequence {
-        private boolean[] drops;
-        private final Object tag;
-        public Unwrap(Element[] e, Object tag)                  { this(e, tag, null); }
-        public Unwrap(Element[] e, Object tag, boolean[] drops) { super(e); this.drops = drops; this.tag = tag; }
-        Sequence _clone() { return new Unwrap(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, 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, true);
+        Forest epsilonForm(Input.Region loc, Grammar cache) {
+            return ((Union)elements[idx]).epsilonForm(loc, cache);
         }
     }
 
     static class RewritingSequence extends Sequence {
         private Object tag;
         private final boolean[] drops;
-        private int count = 0;
+        private final boolean[] lifts;
         Sequence _clone() { return new RewritingSequence(tag, elements, drops); }
         public RewritingSequence(Object tag, Element[] e) { this(tag, e, null); }
-        public RewritingSequence(Object tag, Element[] e, boolean[] drops) {
+        public RewritingSequence(Object tag, Element[] e, boolean[] drops) { this(tag, e, drops, new boolean[e.length]); }
+        public RewritingSequence(Object tag, Element[] e, boolean[] drops, boolean[] lifts) {
             super(e);
             if (tag==null) throw new Error();
             this.tag = tag;
             this.drops = drops == null ? new boolean[e.length] : drops;
+            int count = 0;
             for(int i=0; i<this.drops.length; i++) if (!this.drops[i]) count++;
+            this.lifts = new boolean[count];
+            int j = 0;
+            for(int i=0; i<this.drops.length; i++)
+                if (!this.drops[i])
+                    this.lifts[j++] = lifts[i];
         }
         public <T> Forest<T> postReduce(Input.Region loc, Forest<T>[] args, Position p) {
-            Forest<T>[] args2 = new Forest[count];
+            Forest<T>[] args2 = new Forest[lifts.length];
             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);
+            return Forest.create(loc, (T)tag, args2, lifts);
         }
         public StringBuffer toString(StringBuffer sb, boolean spacing) {
             int len = sb.length();
@@ -295,6 +277,8 @@ 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], lifts);
+        }
     }
-
 }