--- a/Implab/Automaton/RegularExpressions/RegularDFABuilder.cs	Thu Feb 25 02:11:13 2016 +0300
+++ b/Implab/Automaton/RegularExpressions/RegularDFABuilder.cs	Mon Feb 29 02:02:17 2016 +0300
@@ -11,7 +11,7 @@
     /// <see cref="BuildDFA(IDFADefinition)"/> для построения автомата.
     /// </summary>
     public class RegularDFABuilder<TTag> : IVisitor<TTag> {
-        int m_idx = 0;
+        int m_idx;
         Token<TTag> m_root;
         HashSet<int> m_firstpos;
         HashSet<int> m_lastpos;
@@ -26,18 +26,18 @@
 
         public HashSet<int> Followpos(int pos) {
             HashSet<int> set;
-            if (m_followpos.TryGetValue(pos, out set))
-                return set;
-            return m_followpos[pos] = new HashSet<int>();
+            return m_followpos.TryGetValue(pos, out set) ? set : m_followpos[pos] = new HashSet<int>();
         }
 
         bool Nullable(object n) {
             if (n is EmptyToken<TTag> || n is StarToken<TTag>)
                 return true;
-            if (n is AltToken<TTag>)
-                return Nullable(((AltToken<TTag>)n).Left) || Nullable(((AltToken<TTag>)n).Right);
-            if (n is CatToken<TTag>)
-                return Nullable(((CatToken<TTag>)n).Left) && Nullable(((CatToken<TTag>)n).Right);
+            var altToken = n as AltToken<TTag>;
+            if (altToken != null)
+                return Nullable(altToken.Left) || Nullable(altToken.Right);
+            var catToken = n as CatToken<TTag>;
+            if (catToken != null)
+                return Nullable(catToken.Left) && Nullable(catToken.Right);
             return false;
         }
 
@@ -122,7 +122,7 @@
             m_ends.Add(m_idx, token.Tag);
         }
 
-        public void BuildDFA(IDFATransitionTableBuilder<TTag> dfa) {
+        public void BuildDFA(IDFATableBuilder<TTag> dfa) {
             Safe.ArgumentNotNull(dfa,"dfa");
 
             var states = new MapAlphabet<HashSet<int>>(new CustomEqualityComparer<HashSet<int>>(