Exemplo n.º 1
0
        static Set <int> AcceptStates(
            ICollection <Set <int> > states,
            NfaToDfaRenamer renamer,
            Set <int> acceptStates)
        {
            Set <int> result = new Set <int>();

            foreach (Set <int> dfaSubsetState in states)
            {
                if (acceptStates.Any(finalState => dfaSubsetState.Contains(finalState)))
                {
                    result.Add(renamer.ToDfaStateIndex(dfaSubsetState));
                }
            }
            return(result);
        }
Exemplo n.º 2
0
        // Using a renamer (a Map from Set of int to int), replace
        // composite (Set of int) states with simple (int) states in
        // the transition relation trans, which is assumed to be a Map
        // from Set of int to Map from string to Set of int.  The
        // result is a Map from int to Map from string to int.

        // Given a Map from Set of int to Map from string to Set of
        // int, use the result of MkRenamer to replace all Sets of ints
        // by ints.

        static IDictionary <int, Dictionary <TAlphabet, int> > Rename(
            NfaToDfaRenamer renamer,
            IDictionary <Set <int>, Dictionary <TAlphabet, Set <int> > > dfaTrans)
        {
            var newDfaTrans = new SortedDictionary <int, Dictionary <TAlphabet, int> >(); // keys/states are sorted

            foreach (KeyValuePair <Set <int>, Dictionary <TAlphabet, Set <int> > > entry
                     in dfaTrans)
            {
                Set <int> dfaState       = entry.Key;
                var       newDfaTransRow = new Dictionary <TAlphabet, int>();
                foreach (KeyValuePair <TAlphabet, Set <int> > tr in entry.Value)
                {
                    newDfaTransRow.Add(tr.Key, renamer.ToDfaStateIndex(tr.Value));
                }
                newDfaTrans.Add(renamer.ToDfaStateIndex(dfaState), newDfaTransRow);
            }

            return(newDfaTrans);
        }
Exemplo n.º 3
0
        /// <summary>
        /// McNaughton-Yamada-Thompson algorithm (aka Thompson's construction)
        /// </summary>
        public Dfa <TAlphabet> ToDfa(bool skipRenaming = false)
        {
            IDictionary <Set <int>, Dictionary <TAlphabet, Set <int> > >
            cDfaTrans = CompositeDfaTrans(Start, Trans);

            Set <int> cDfaStart = EpsilonClose(new Set <int>(new [] { Start }), Trans);

            ICollection <Set <int> > cDfaStates = cDfaTrans.Keys;

            var renamer = new NfaToDfaRenamer(cDfaStates, skipRenaming, _predicate);

            // DFA-transitions (delta)
            IDictionary <int, Dictionary <TAlphabet, int> > dfaTrans =
                Rename(renamer, cDfaTrans);

            // The singleton start state = q_0
            int dfaStartStateIndex = renamer.ToDfaStateIndex(cDfaStart);

            // The subset of accepting states = F
            Set <int> dfaAcceptingStateIndices = AcceptStates(cDfaStates, renamer, AcceptingStates);

            return(new Dfa <TAlphabet>(dfaStartStateIndex, dfaAcceptingStateIndices, dfaTrans, renamer));
        }