fix major bug: create YieldSet2 which does not consider needs/hates
[sbp.git] / src / edu / berkeley / sbp / Walk.java
index 5e1f534..e2ac662 100644 (file)
@@ -18,7 +18,7 @@ abstract class Walk<T> {
     public Walk() { this(null); }
     public Walk(Cache c) { this.c = c; }
 
-    public  T sequence(Sequence s) {
+    public  T walkSequence(Sequence s) {
         T ret = bottom(s);
         for(Position p = s.firstp(); p!=null && !p.isLast(); p = p.next())
             ret = sequence(s, ret, walk(p.element()));
@@ -36,16 +36,11 @@ abstract class Walk<T> {
 
     protected T walk2(SequenceOrElement e) {
         if      (e instanceof Atom)     return walkAtom((Atom)e);
-        else if (e instanceof Sequence) return sequence((Sequence)e);
+        else if (e instanceof Sequence) return walkSequence((Sequence)e);
         else if (e instanceof Union) {
             T ret = bottom(e);
-            for(Sequence s : (Union)e) {
+            for(Sequence s : (Union)e)
                 ret = union((Union)e, ret, walk(s));
-
-                // FIXME
-                for(Sequence ss : s.needs()) ret = union((Union)e, ret, walk(ss));
-                for(Sequence ss : s.hates()) ret = union((Union)e, ret, walk(ss));
-            }
             return ret;
         } else {
             throw new Error("unknown element of class " + e.getClass().getName() + ": " + e);
@@ -57,13 +52,62 @@ abstract class Walk<T> {
         public final HashSet<SequenceOrElement> walk() { return walk(e); }
         public YieldSet(SequenceOrElement e, Cache c)  { super(c); this.e = e; }
         public HashSet<SequenceOrElement> bottom(SequenceOrElement e)     { return acc; }
-        public HashSet<SequenceOrElement> sequence(Sequence seq) { return bottom(seq); }
+        public HashSet<SequenceOrElement> walkSequence(Sequence seq) { return bottom(seq); }
+        public HashSet<SequenceOrElement> walkAtom(Atom r) {
+            c.atoms.put(e, c.atoms.get(e)==null ? r : c.atoms.get(e).union(r));
+            return super.walkAtom(r);
+        }
+        protected HashSet<SequenceOrElement> walk2(SequenceOrElement e) {
+            HashSet<SequenceOrElement> ret = super.walk2(e);
+            if (e instanceof Union)
+                for(Sequence s : (Union)e) {
+                    for(Sequence ss : s.needs()) ret = union((Union)e, ret, walk(ss));
+                    for(Sequence ss : s.hates()) ret = union((Union)e, ret, walk(ss));
+                }
+            return ret;
+        }
+    }
+
+    static class YieldSet2 extends Walk<HashSet<SequenceOrElement>> {
+        private final SequenceOrElement e;
+        public final HashSet<SequenceOrElement> walk() { return walk(e); }
+        public YieldSet2(SequenceOrElement e, Cache c)  { super(c); this.e = e; }
+        public HashSet<SequenceOrElement> bottom(SequenceOrElement e)     { return acc; }
+        public HashSet<SequenceOrElement> walkSequence(Sequence seq) { return bottom(seq); }
         public HashSet<SequenceOrElement> walkAtom(Atom r) {
             c.atoms.put(e, c.atoms.get(e)==null ? r : c.atoms.get(e).union(r));
             return super.walkAtom(r);
         }
     }
 
+    static class EquivalentTo extends Walk<HashSet<Sequence>> {
+        private final Sequence s;
+        private final HashSet<Sequence> eq = new HashSet<Sequence>();
+        public final HashSet<Sequence> walk() { return walk(s); }
+        public EquivalentTo(Sequence e, Cache c)  {
+            super(c); this.s = e;
+        }
+        public HashSet<Sequence> bottom(SequenceOrElement e)     { return eq; }
+        public HashSet<Sequence> walkSequence(Sequence seq) {
+            eq.add(seq);
+            Position p = seq.firstp();
+            for(; !p.isLast(); p = p.next()) {
+                if (!p.isLast() && isRightNullable(p.next()))
+                    walk(p.element());
+                if (!c.possiblyEpsilon(p.element())) break;
+            }
+            return eq;
+        }
+        public HashSet<Sequence> walkAtom(Atom r) {
+            return eq;
+        }
+        private boolean isRightNullable(Position p) {
+            if (p.isLast()) return true;
+            if (!c.possiblyEpsilon(p.element())) return false;
+            return isRightNullable(p.next());
+        }
+    }
+
 
     // Boolean //////////////////////////////////////////////////////////////////////////////
 
@@ -82,6 +126,34 @@ abstract class Walk<T> {
         }
     }
 
+    static class EpsilonFollowSet extends Walk<Atom> {
+        Atom all;
+        Atom empty;
+        public EpsilonFollowSet(Atom a, Atom empty, Cache c) {
+            super(c);
+            this.all = all;
+            this.empty = empty;
+        }
+        public Atom walkAtom(Atom r) { return all; }
+        public Atom walkSequence(Sequence s) {
+            if (s.follow==null) return all;
+            return s.follow;
+        }
+        public Atom sequence(Sequence s, Atom a, Atom b)  {
+            throw new RuntimeException();
+        }
+        public Atom union(Union u, Atom a, Atom b) {
+            /*
+            if (a==null) return b;
+            if (b==null) return a;
+            */
+            if (a==null || b==null) return all;
+            return (Atom)a.union(b);
+        }
+        public Atom bottom(SequenceOrElement e) {
+            return (e instanceof Union) ? empty : all;
+        }
+    }
 
     // Input-Set //////////////////////////////////////////////////////////////////////////////
 
@@ -93,9 +165,10 @@ abstract class Walk<T> {
         public Topology<Tok> walkAtom(Atom r)          { cs = cs.union(r.getTokenTopology()); return cs; }
     }
 
+    // feature: intersect with "first" set of all positive conjuncts
     static class First<Tok extends Input> extends WalkTokenSet<Tok> {
         public First(Topology<Tok> cs, Walk.Cache cache) { super(cs, cache); }
-        public Topology<Tok> sequence(Sequence seq) {
+        public Topology<Tok> walkSequence(Sequence seq) {
             for(Position p = seq.firstp(); p!=null && !p.isLast(); p = p.next()) {
                 walk(p.element());
                 if (!c.possiblyEpsilon(p.element())) break;
@@ -112,7 +185,7 @@ abstract class Walk<T> {
         public Follow(Topology<Tok> cs, SequenceOrElement me, HashSet<SequenceOrElement> all, Cache c)  {
           super(cs, c); this.me = me; this.all = all; }
         public Topology<Tok> bottom(SequenceOrElement e)                       { return cs; }
-        public Topology<Tok> sequence(Sequence seq)                  { return cs; }
+        public Topology<Tok> walkSequence(Sequence seq)                  { return cs; }
         public Topology<Tok> walkAtom(Atom r) { return walk((SequenceOrElement)r); }
         public Topology<Tok> walk(SequenceOrElement e) {
             if (acc.contains(e)) return bottom(e);
@@ -180,6 +253,7 @@ abstract class Walk<T> {
         public HashMap<SequenceOrElement,Boolean> eof = new HashMap<SequenceOrElement,Boolean>();
         public HashMap<SequenceOrElement,Topology> follow = new HashMap<SequenceOrElement,Topology>();
         public HashMapBag<SequenceOrElement,SequenceOrElement>  ys = new HashMapBag<SequenceOrElement,SequenceOrElement>();
+        public HashMapBag<SequenceOrElement,SequenceOrElement>  ys2 = new HashMapBag<SequenceOrElement,SequenceOrElement>();
         public HashMap<SequenceOrElement,Topology> atoms = new HashMap<SequenceOrElement,Topology>();
         public <Tok extends Input> Topology<Tok> first(SequenceOrElement e, Topology<Tok> empty) {
             return new Walk.First<Tok>(empty, this).walk(e);