--- a/Implab/Automaton/RegularExpressions/RegularExpressionVisitor.cs	Tue Mar 22 18:58:40 2016 +0300
+++ b/Implab/Automaton/RegularExpressions/RegularExpressionVisitor.cs	Wed Mar 23 01:42:00 2016 +0300
@@ -12,13 +12,14 @@
     /// </summary>
     public class RegularExpressionVisitor<TTag> : IVisitor<TTag> {
         int m_idx;
-        Token<TTag> m_root;
+        Token m_root;
         HashSet<int> m_firstpos;
         HashSet<int> m_lastpos;
 
         readonly Dictionary<int, HashSet<int>> m_followpos = new Dictionary<int, HashSet<int>>();
         readonly Dictionary<int, int> m_indexes = new Dictionary<int, int>();
-        readonly Dictionary<int, TTag> m_ends = new Dictionary<int, TTag>();
+        readonly HashSet<int> m_ends = new HashSet<int>();
+        readonly Dictionary<int, TTag> m_tags = new Dictionary<int, TTag>();
 
         public Dictionary<int, HashSet<int>> FollowposMap {
             get { return m_followpos; }
@@ -30,19 +31,19 @@
         }
 
         bool Nullable(object n) {
-            if (n is EmptyToken<TTag> || n is StarToken<TTag>)
+            if (n is EmptyToken || n is StarToken)
                 return true;
-            var altToken = n as AltToken<TTag>;
+            var altToken = n as AltToken;
             if (altToken != null)
                 return Nullable(altToken.Left) || Nullable(altToken.Right);
-            var catToken = n as CatToken<TTag>;
+            var catToken = n as CatToken;
             if (catToken != null)
                 return Nullable(catToken.Left) && Nullable(catToken.Right);
             return false;
         }
 
 
-        public void Visit(AltToken<TTag> token) {
+        public void Visit(AltToken token) {
             if (m_root == null)
                 m_root = token;
             var firtspos = new HashSet<int>();
@@ -60,7 +61,7 @@
             m_lastpos = lastpos;
         }
 
-        public void Visit(StarToken<TTag> token) {
+        public void Visit(StarToken token) {
             if (m_root == null)
                 m_root = token;
             token.Token.Accept(this);
@@ -69,7 +70,7 @@
                 Followpos(i).UnionWith(m_firstpos);
         }
 
-        public void Visit(CatToken<TTag> token) {
+        public void Visit(CatToken token) {
             if (m_root == null)
                 m_root = token;
 
@@ -97,12 +98,12 @@
 
         }
 
-        public void Visit(EmptyToken<TTag> token) {
+        public void Visit(EmptyToken token) {
             if (m_root == null)
                 m_root = token;
         }
 
-        public void Visit(SymbolToken<TTag> token) {
+        public void Visit(SymbolToken token) {
             if (m_root == null)
                 m_root = token;
             m_idx++;
@@ -119,7 +120,19 @@
             m_firstpos = new HashSet<int>(new[] { m_idx });
             m_lastpos = new HashSet<int>(new[] { m_idx });
             Followpos(m_idx);
-            m_ends.Add(m_idx, token.Tag);
+            m_ends.Add(m_idx);
+            m_tags.Add(m_idx, token.Tag);
+        }
+
+        public void Visit(EndToken token) {
+            if (m_root == null)
+                m_root = token;
+            m_idx++;
+            m_indexes[m_idx] = DFAConst.UNCLASSIFIED_INPUT;
+            m_firstpos = new HashSet<int>(new[] { m_idx });
+            m_lastpos = new HashSet<int>(new[] { m_idx });
+            Followpos(m_idx);
+            m_ends.Add(m_idx);
         }
 
         public void BuildDFA(ITaggedDFABuilder<TTag> dfa) {
@@ -157,14 +170,18 @@
                         }
                     }
                     if (next.Count > 0) {
-                        int s2 = states.Translate(next);
-                        if (s2 == DFAConst.UNCLASSIFIED_INPUT) {
+                        int s2;
+                        if (states.Contains(next)) {
+                            s2 = states.Translate(next);
+                        } else {
                             s2 = states.DefineSymbol(next);
 
-                            tags = GetStateTags(next);
-                            if (tags != null && tags.Length > 0) {
+                            if (IsFinal(next)) {
+                                
                                 dfa.MarkFinalState(s2);
-                                dfa.SetStateTag(s2, tags);
+                                tags = GetStateTags(next);
+                                if (tags != null && tags.Length > 0)
+                                    dfa.SetStateTag(s2, tags);
                             }
                             
                             queue.Enqueue(next);
@@ -175,9 +192,14 @@
             }
         }
 
+        bool IsFinal(IEnumerable<int> state) {
+            Debug.Assert(state != null);
+            return state.Any(m_ends.Contains);
+        }
+
         TTag[] GetStateTags(IEnumerable<int> state) {
             Debug.Assert(state != null);
-            return state.Where(m_ends.ContainsKey).Select(pos => m_ends[pos]).ToArray();
+            return state.Where(m_tags.ContainsKey).Select(pos => m_tags[pos]).ToArray();
         }
 
     }