public bool addState(State state)
{
if (isStatePresent(state))
{
return false;
}
state.QLabel = "q" + qcounter++.ToString();
States.Add(state);
return true;
}
public DFA(RegularExpression re)
{
States = new List<State>();
InitState = new State(re, DFABuilder.IsExpressionFinal(re));
InitState.QLabel = "q0";
Transitions = new List<Transition>();
States.Add(InitState);
Alphabet = new HashSet<char>();
foreach (char c in re.Value)
{
if (Char.IsLetter(c))
Alphabet.Add(c);
}
}
public bool addTransition(State to, char trans)
{
bool present = false;
foreach(KeyValuePair<char,State> s in transistions)
{
if (s.Value.RegexLabel == to.RegexLabel && s.Key == trans)
{
present = true;
break;
}
}
if (!present)
{
transistions.Add(trans, to);
return true;
}
else
return false;
}
private bool isStatePresent(State state)
{
foreach (State s in States)
{
if (s.RegexLabel == state.RegexLabel)
return true;
}
return false;
}
public void buildDFA(string re)
{
Dfa = new DFA(new RegularExpression(re));
var newStates = new HashSet<State>();
var newTransitions = new List<Transition>();
var newSteps = new List<Step>();
int added = 0;
do
{
added = 0;
newStates.Clear();
newTransitions.Clear();
newSteps.Clear();
foreach (State state in Dfa.States)
{
foreach (char c in Dfa.Alphabet)
{
RegularExpression newRegEx = Derive(new RegularExpression(state.RegexLabel), c);
State newState = null;
newState = new State(newRegEx, IsExpressionFinal(newRegEx));
newStates.Add(newState);
newTransitions.Add(new Transition(state.RegexLabel, newState.RegexLabel, c));
Step newStep = new Step(state, newState, c);
newSteps.Add(newStep);
}
}
foreach (State state in newStates)
{
bool hasSubstring = false;
foreach (State s1 in Dfa.States)
{
if(state.RegexLabel.Contains(s1.RegexLabel) && state.RegexLabel != s1.RegexLabel)
{
hasSubstring = true;
break;
}
}
State equivalent = null;
if (hasSubstring)
{
var testWindow = new UserInteraction(state.RegexLabel, Dfa.States);
if (testWindow.ShowDialog() == false)
{
equivalent = testWindow.GetSelectedState();
}
if (equivalent == null)
{
if (Dfa.addState(state))
{
added++;
}
}
else
{
// update transitions
foreach (Transition t in Dfa.Transitions)
{
if (t.From == state.RegexLabel)
t.From = equivalent.RegexLabel;
if (t.To == state.RegexLabel)
t.To = equivalent.RegexLabel;
}
foreach (Transition t in newTransitions)
{
if (t.From == state.RegexLabel)
t.From = equivalent.RegexLabel;
if (t.To == state.RegexLabel)
t.To = equivalent.RegexLabel;
}
//update steps
foreach (Step step in Steps)
{
if (step.From.RegexLabel == state.RegexLabel)
step.From.RegexLabel = equivalent.RegexLabel;
if (step.To.RegexLabel == state.RegexLabel)
step.To.RegexLabel = equivalent.RegexLabel;
}
foreach (Step step in newSteps)
{
if (step.From.RegexLabel == state.RegexLabel)
step.From.RegexLabel = equivalent.RegexLabel;
if (step.To.RegexLabel == state.RegexLabel)
step.To.RegexLabel = equivalent.RegexLabel;
}
if (Dfa.addState(equivalent))
{
added++;
}
}
}
if (Dfa.addState(state))
{
added++;
}
}
foreach (Transition t in newTransitions)
{
bool isTransitionAlreadyPresent = false;
foreach (Transition t1 in Dfa.Transitions)
{
if (t1.From == t.From && t1.To == t.To && t.Over == t1.Over)
{
isTransitionAlreadyPresent = true;
break;
}
}
if (isTransitionAlreadyPresent)
continue;
Dfa.Transitions.Add(t);
}
foreach (Step step in newSteps)
{
bool isStepAlreadyPresent = false;
foreach (Step s1 in Steps)
{
if (step.From.RegexLabel == s1.From.RegexLabel && step.To.RegexLabel == s1.To.RegexLabel && step.Over == s1.Over)
{
isStepAlreadyPresent = true;
break;
}
}
if (isStepAlreadyPresent)
continue;
Steps.Add(step);
}
} while (added != 0);
}
private void btnStartSimulation_Click(object sender, RoutedEventArgs e)
{
if (txtWord.Text.Length == 0)
{
MessageBox.Show("Enter a word first.");
return;
}
_word = txtWord.Text;
foreach (char c in _word)
{
if (!_dfa.Alphabet.Contains(c))
{
MessageBox.Show("Not accepted - your word contains illegal characters or letters, that do not belong to the alphabet.");
return;
}
}
_currentChar = 0;
_currentState = _dfa.InitState;
string dot = generateDot();
BitmapImage bmp = dot2bmp(dot);
imgGraph.Source = bmp;
btnNextStep.IsEnabled = true;
btnStartSimulation.IsEnabled = false;
if (_word.Length == 1)
{
if (_currentState.IsFinal)
{
MessageBox.Show("The word \"" + _word + "\" is accepted.");
}
else
{
MessageBox.Show("The word \"" + _word + "\" is not accepted.");
}
btnNextStep.IsEnabled = false;
btnStartSimulation.IsEnabled = true;
}
}
private string generateDot()
{
State newCurrentState = null;
// find new current state
foreach (Transition t in _dfa.Transitions)
{
if (t.From == _currentState.RegexLabel && t.Over == _word[_currentChar])
{
foreach (State s in _dfa.States)
{
if (s.RegexLabel == t.To)
{
newCurrentState = s;
break;
}
}
break;
}
}
StringBuilder sbFsm = new StringBuilder();
sbFsm.Append("digraph finite_state_machine { rankdir=LR; size=\"7,5\" ");
StringBuilder sbFinalStates = new StringBuilder();
foreach (State state in _dfa.FinalStates)
{
sbFinalStates.Append("\"");
sbFinalStates.Append(state.QLabel);
sbFinalStates.Append("\" ");
}
//sbFinalStates.Append("; ");
sbFsm.Append("node [shape = doublecircle]; ");
sbFsm.Append(sbFinalStates.ToString());
sbFsm.Append("node [shape = circle]; ");
for (int i = 0; i < _dfaBuilder.Steps.Count; i++)
{
State from = _dfa.States.LastOrDefault(s => s.RegexLabel == _steps[i].From.RegexLabel);
State to = _dfa.States.LastOrDefault(s => s.RegexLabel == _steps[i].To.RegexLabel);
sbFsm.Append(from.QLabel);
sbFsm.Append(" -> ");
sbFsm.Append(to.QLabel);
sbFsm.Append(" [ label = \"");
sbFsm.Append(_steps[i].Over);
sbFsm.Append("\"");
if(from.RegexLabel == _currentState.RegexLabel && to.RegexLabel == newCurrentState.RegexLabel && _steps[i].Over == _word[_currentChar])
sbFsm.Append(", color=red");
sbFsm.Append("] ; ");
}
sbFsm.Append("\"" + _currentState.QLabel + "\" [color=red];");
sbFsm.Append("\"" + newCurrentState.QLabel + "\" [color=red]");
sbFsm.Append("}");
_currentChar++;
_currentState = newCurrentState;
return sbFsm.ToString();
}
private void lstStates_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
_selectedState = (State) lstStates.SelectedItem;
}
public Step(State from, State to, char over)
{
From = from;
To = to;
Over = over;
}