Example #1
0
        public (string, string) ConvertNFAToRegEx()
        {
            RegexAutomata regexAutomata = NFAtoRegEx.ConvertNFAToRegEx(automata);

            CreateAutomatePicture(NFAtoRegEx.CreateRegexAutomataDotString(regexAutomata));
            return(regexAutomata.Nodes[0].Connections[0].Expression, regexAutomata.Nodes[0].Connections[0].PreExpr);
        }
Example #2
0
        public void RerouteTransitions(RegexNode toNode, RegexAutomata automata)
        {
            (List <RegexConnection>, string, string)splitTransitions = SplitSelfLoopingTransition(toNode);
            List <RegexConnection> toTransitionList = splitTransitions.Item1;
            string betweenTransition    = splitTransitions.Item2;
            string betweenPreTransition = splitTransitions.Item3;

            foreach (RegexNode node in automata.Nodes)
            {
                //can assume this is only once since we union all double transitions
                RegexConnection        pruneConnection = null;
                List <RegexConnection> addList         = new List <RegexConnection>();
                if (node != toNode)
                {
                    foreach (RegexConnection trans in node.Connections)
                    {
                        if (trans.ToNode == toNode)
                        {
                            pruneConnection = trans;
                            foreach (RegexConnection toTransition in toTransitionList)
                            {
                                string newExpression = CreateNewExpressionString(trans.Expression, betweenTransition, toTransition.Expression);
                                string newPreExpr    = CreateNewPreExpressionString(trans.PreExpr, betweenPreTransition, toTransition.PreExpr);

                                addList.Add(new RegexConnection(newExpression, newPreExpr, toTransition.ToNode));
                            }
                        }
                    }
                }
                node.Connections.Remove(pruneConnection);
                node.Connections.AddRange(addList);
            }
            automata.Nodes.Remove(toNode);
        }
Example #3
0
        public string CreateRegexAutomataDotString(RegexAutomata automata)
        {
            string dotString = "";

            dotString += "digraph myAutomaton { \nrankdir=LR; \n\"\" [shape=none] \n";

            foreach (RegexNode node in automata.Nodes)
            {
                string shape = "circle";
                if (node.Final)
                {
                    shape = "doublecircle";
                }
                dotString += $"\"{node.Name}\" [shape={shape}] \n";
            }

            dotString += "\n";


            dotString += $"\"\" -> \"{automata.Nodes[0].Name}\" \n";


            foreach (RegexNode node in automata.Nodes)
            {
                foreach (RegexConnection conn in node.Connections)
                {
                    string expres = conn.Expression.Replace("∪", "|");
                    dotString += $"\"{node.Name}\" -> \"{conn.ToNode.Name}\" [label=\"{expres}\"] \n";
                }
            }

            dotString += "}";

            return(dotString);
        }
Example #4
0
        public RegexAutomata ConvertNFAToRegEx(Automata automata)
        {
            RegexAutomata regexAutomata = new RegexAutomata(automata);

            UnionMultipleTransitions(regexAutomata);
            regexAutomata = PruneNodes(regexAutomata);
            return(regexAutomata);
        }
Example #5
0
        public RegexAutomata PruneNodes(RegexAutomata automata)
        {
            int nodeCount = automata.Nodes.Count - 2;

            if (nodeCount - 2 < 5)
            {
                RegexAutomata smalllestRegexGnfa = null;
                IEnumerable <IEnumerable <int> > allPermutations = GetPermutations(Enumerable.Range(1, nodeCount), nodeCount);
                foreach (IEnumerable <int> permutation in allPermutations)
                {
                    RegexAutomata    automataCopy = automata.DeepClone();
                    List <RegexNode> nodeOrder    = new List <RegexNode>();
                    foreach (int nodeIndex in permutation)
                    {
                        nodeOrder.Add(automataCopy.Nodes[nodeIndex]);
                    }
                    foreach (RegexNode currentNode in nodeOrder)
                    {
                        RerouteTransitions(currentNode, automataCopy);
                        UnionMultipleTransitions(automataCopy);
                    }
                    Console.WriteLine($"Permutation {{{PermutationString(permutation)}}}: {automataCopy.Nodes[0].Connections[0].PreExpr}");
                    if (smalllestRegexGnfa == null || smalllestRegexGnfa.Nodes[0].Connections[0].PreExpr.Length > automataCopy.Nodes[0].Connections[0].PreExpr.Length)
                    {
                        smalllestRegexGnfa = automataCopy;
                    }
                }
                return(smalllestRegexGnfa);
            }
            else
            {
                while (automata.Nodes.Count > 2)
                {
                    RegexNode currentNode = automata.Nodes[1];

                    RerouteTransitions(currentNode, automata);
                    UnionMultipleTransitions(automata);
                }
                return(automata);
            }
        }
Example #6
0
 public void UnionMultipleTransitions(RegexAutomata automata)
 {
     foreach (RegexNode node in automata.Nodes)
     {
         Dictionary <RegexNode, List <RegexConnection> > transitionsPerNode = new Dictionary <RegexNode, List <RegexConnection> >();
         foreach (RegexConnection trans in node.Connections)
         {
             if (transitionsPerNode.ContainsKey(trans.ToNode))
             {
                 transitionsPerNode[trans.ToNode].Add(trans);
             }
             else
             {
                 transitionsPerNode.Add(trans.ToNode, new List <RegexConnection>()
                 {
                     trans
                 });
             }
         }
         if (transitionsPerNode.Count != node.Connections.Count)
         {
             List <RegexConnection> newTransitions = new List <RegexConnection>();
             foreach (KeyValuePair <RegexNode, List <RegexConnection> > valuePair in transitionsPerNode)
             {
                 HashSet <string> uniqueExprs    = new HashSet <string>();
                 HashSet <string> uniquePreExprs = new HashSet <string>();
                 foreach (RegexConnection connection in valuePair.Value)
                 {
                     uniqueExprs.Add(connection.Expression);
                     uniquePreExprs.Add(connection.PreExpr);
                 }
                 //infix expr
                 string newExpr = "";
                 foreach (string expr in uniqueExprs)
                 {
                     if (expr.Length == 1 || (expr.Substring(0, 1).Equals("(") && expr.Substring(expr.Length - 1, 1).Equals(")")))
                     {
                         newExpr += $"{expr}∪";
                     }
                     else
                     {
                         newExpr += $"({expr})∪";
                     }
                 }
                 string newPreExpr = "";
                 //prefix expr
                 bool firstPreExpr = false;
                 foreach (string preExpr in uniquePreExprs)
                 {
                     if (!firstPreExpr)
                     {
                         firstPreExpr = true;
                         newPreExpr   = preExpr;
                     }
                     else
                     {
                         newPreExpr = $"|({newPreExpr},{preExpr})";
                     }
                 }
                 newTransitions.Add(new RegexConnection(newExpr.Substring(0, newExpr.Length - 1), newPreExpr, valuePair.Key));
             }
             node.Connections = newTransitions;
         }
     }
 }