public NDFA <int, char> toNDFA(ref int i)
{
NDFA <int, char> ndfaLeft = left?.toNDFA(ref i);
NDFA <int, char> ndfaRight = right?.toNDFA(ref i);
var ndfa = new NDFA <int, char>('$', ndfaLeft, ndfaRight);
switch (op)
{
case Operator.ONE:
var currState = ++i;
ndfa.addStartState(currState);
foreach (var terminal in terminals)
{
ndfa.addTransition(terminal, currState, currState = ++i);
}
ndfa.addEndState(currState);
break;
case Operator.OR:
var orStartState = ++i;
var orEndState = ++i;
ndfa.addStartState(orStartState);
ndfa.addTransition(ndfa.Epsilon, orStartState, ndfaLeft.StartStates.First());
ndfa.addTransition(ndfa.Epsilon, orStartState, ndfaRight.StartStates.First());
ndfa.addTransition(ndfa.Epsilon, ndfaLeft.EndStates.Last(), orEndState);
ndfa.addTransition(ndfa.Epsilon, ndfaRight.EndStates.Last(), orEndState);
ndfa.addEndState(orEndState);
break;
case Operator.DOT:
ndfa.addStartState(ndfaLeft.StartStates.First());
ndfa.addEndState(ndfaRight.EndStates.Last());
ndfa.addTransition(ndfa.Epsilon, ndfaLeft.EndStates.Last(), ndfaRight.StartStates.First());
break;
case Operator.PLUS:
ndfa = plusAndStarOperatorHandlerCalledByToNDFA(ndfa, ndfaLeft, ref i);
break;
case Operator.STAR:
ndfa = plusAndStarOperatorHandlerCalledByToNDFA(ndfa, ndfaLeft, ref i);
break;
default:
break;
}
return(ndfa);
}
public NDFA <T, U> reverse(U epsilon)
{
NDFA <T, U> result = new NDFA <T, U>(epsilon);
// Add DFA's startstate as endstate
result.addEndState(StartState);
foreach (T endState in EndStates)
{
result.addStartState(endState);
}
forEachTransition((terminal, fromState, toState)
=> result.addTransition(terminal, toState, fromState));
return(result);
}
private NDFA <int, char> plusAndStarOperatorHandlerCalledByToNDFA(NDFA <int, char> ndfa, NDFA <int, char> left, ref int i)
{
var startState = ++i;
var endState = ++i;
ndfa.addStartState(startState);
ndfa.addEndState(endState);
ndfa.addTransition(ndfa.Epsilon, startState, left.StartStates.First());
ndfa.addTransition(ndfa.Epsilon, left.EndStates.Last(), left.StartStates.First());
ndfa.addTransition(ndfa.Epsilon, left.EndStates.Last(), endState);
if (op == Operator.STAR)
{
ndfa.addTransition(ndfa.Epsilon, startState, endState);
}
return(ndfa);
}
public static void init()
{
// Starts with abb or ends with baab
dfa.addStartState(0);
dfa.addEndState(3);
dfa.addEndState(8);
dfa.addTransition('a', 0, 1);
dfa.addTransition('b', 0, 4);
dfa.addTransition('a', 1, 4);
dfa.addTransition('b', 1, 2);
dfa.addTransition('a', 2, 4);
dfa.addTransition('b', 2, 3);
dfa.addTransition('a', 3, 3);
dfa.addTransition('b', 3, 3);
dfa.addTransition('a', 4, 4);
dfa.addTransition('b', 4, 5);
dfa.addTransition('a', 5, 6);
dfa.addTransition('b', 5, 5);
dfa.addTransition('a', 6, 7);
dfa.addTransition('b', 6, 5);
dfa.addTransition('a', 7, 4);
dfa.addTransition('b', 7, 8);
dfa.addTransition('a', 8, 6);
dfa.addTransition('b', 8, 5);
// Ends with a, or bc
ndfa.addStartState(1);
ndfa.addEndState(9);
ndfa.addTransition('a', 1, 1);
ndfa.addTransition('b', 1, 1);
ndfa.addTransition('$', 1, 2);
ndfa.addTransition('$', 1, 9);
ndfa.addTransition('$', 2, 4);
ndfa.addTransition('$', 2, 6);
ndfa.addTransition('a', 4, 5);
ndfa.addTransition('$', 5, 3);
ndfa.addTransition('$', 2, 6);
ndfa.addTransition('b', 6, 7);
ndfa.addTransition('c', 7, 8);
ndfa.addTransition('$', 8, 9);
ndfa.addTransition('$', 3, 2);
ndfa.addTransition('$', 3, 9);
ndfa.addTransition('$', 1, 9);
ndfa2.addStartState(1);
ndfa2.addEndState(3);
ndfa2.addEndState(5);
ndfa2.addTransition('a', 1, 3);
ndfa2.addTransition('b', 1, 3);
ndfa2.addTransition('b', 1, 2);
ndfa2.addTransition('b', 2, 3);
ndfa2.addTransition('$', 2, 3);
ndfa2.addTransition('a', 3, 4);
ndfa2.addTransition('b', 3, 4);
ndfa2.addTransition('a', 3, 5);
ndfa2.addTransition('a', 4, 3);
ndfa2.addTransition('a', 4, 2);
ndfa2.addTransition('$', 5, 4);
ndfa2.addTransition('b', 5, 5);
// ends with 'bbab'
dfa1.addStartState(1);
dfa1.addEndState(5);
dfa1.addTransition('b', 1, 2);
dfa1.addTransition('a', 1, 1);
dfa1.addTransition('b', 2, 3);
dfa1.addTransition('a', 2, 1);
dfa1.addTransition('b', 3, 3);
dfa1.addTransition('a', 3, 4);
dfa1.addTransition('b', 4, 5);
dfa1.addTransition('a', 4, 1);
dfa1.addTransition('a', 5, 1);
dfa1.addTransition('b', 5, 3);
// Even amount of b's
dfa2.addStartState(1);
dfa2.addEndState(1);
dfa2.addTransition('a', 1, 1);
dfa2.addTransition('b', 1, 2);
dfa2.addTransition('a', 2, 2);
dfa2.addTransition('b', 2, 1);
}