checkpoint

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

diff --git a/src/edu/berkeley/sbp/Walk.java b/src/edu/berkeley/sbp/Walk.java
index f8f8d4f..380d09b 100644 (file)
--- a/src/edu/berkeley/sbp/Walk.java
+++ b/src/edu/berkeley/sbp/Walk.java
@@ -1,7 +1,6 @@
 package edu.berkeley.sbp;
-import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
 import edu.berkeley.sbp.*;
+import edu.berkeley.sbp.util.*;
 import edu.berkeley.sbp.Sequence.Position;
 import java.io.*;
 import java.util.*;
@@ -86,7 +85,7 @@ abstract class Walk<T> {
         public Topology<Tok> walkAtom(Atom r)          { cs = cs.union(r); return cs; }
     }
 
-    class First<Tok extends Token> extends WalkTokenSet<Tok> {
+    static class First<Tok extends Token> extends WalkTokenSet<Tok> {
         public First(Topology<Tok> cs, Walk.Cache cache) { super(cs, cache); }
         public Topology<Tok> sequence(Sequence seq) {
             for(Position p = seq.firstp(); p!=null && !p.isLast(); p = p.next()) {
@@ -97,20 +96,6 @@ abstract class Walk<T> {
         }
     }
 
-    class Last<Tok extends Token> extends WalkTokenSet<Tok> {
-        public Last(Topology<Tok> cs, Walk.Cache cache) { super(cs, cache); }
-        public Topology<Tok> sequence(Sequence seq) { sequence(seq.firstp()); return cs; }
-        private Topology<Tok> sequence(Position p) {
-            if (p==null) return null;
-            Topology<Tok> ret = sequence(p.next());
-            if (ret!=null) return ret;
-            if (p.isLast()) return null;
-            if (p.element().possiblyEpsilon(c)) return null;
-            if (p.element()==null) return null;
-            return walk(p.element());
-        }
-    }
-
     static class Follow<Tok extends Token> extends WalkTokenSet<Tok> {
         private final Element me;
         private final HashSet<Element> all;
@@ -135,18 +120,16 @@ abstract class Walk<T> {
 
             Topology<Tok> cso = cs;
             boolean eofo = eof;
-            eof = false;
+            eof = c.eof.get(e) != null && c.eof.get(e).booleanValue();
             cs = cso.empty();
 
-            if (e instanceof Parser.Top) eof = true;
             for(Element x : all) {
                 boolean matched = false;
-                if (x instanceof Parser.Top) walk(x); // because this symbol might not appear in any other Sequence
                 if (!(x instanceof Sequence)) continue;
                 Sequence a = (Sequence)x;
                 Position mp = null;
                 for(Position pos = a.firstp(); pos != null && !pos.isLast(); pos = pos.next()) {
-                    if (matched) cs = cs.union(new First<Tok>(cs.empty(), c).walk(pos.element()));
+                    if (matched) cs = cs.union(c.first(pos.element(), cs.empty()));
                     if (pos.isLast()) { matched = (matched && pos.element().possiblyEpsilon(c)); continue; }
                     boolean good = false;
                     if (e instanceof Atom) {
@@ -154,7 +137,7 @@ abstract class Walk<T> {
                         if (top==null) continue;
                         if (!(top.containsAll(((Atom)e)))) continue;
                     } else {
-                        if (c.ys.get(pos.element()).contains(e)) good = true;
+                        if (c.ys.contains(pos.element(),e)) good = true;
                     }
                     if (good) {
                         mp = pos;
@@ -187,7 +170,10 @@ abstract class Walk<T> {
         public final HashMap<Element,Boolean> possiblyEpsilon = new HashMap<Element,Boolean>();
         public HashMap<Element,Boolean> eof = new HashMap<Element,Boolean>();
         public HashMap<Element,Topology> follow = new HashMap<Element,Topology>();
-        public HashMap<Element,HashSet<Element>>  ys            = new HashMap<Element,HashSet<Element>>();
+        public HashMapBag<Element,Element>  ys = new HashMapBag<Element,Element>();
         public HashMap<Element,Topology> atoms = new HashMap<Element,Topology>();
+        public <Tok extends Token> Topology<Tok> first(Element e, Topology<Tok> empty) {
+            return new Walk.First<Tok>(empty, this).walk(e);
+        }
     }
 }