public static NFA CreateAutomaton(string a)
{
var result = new NFA();
var start = 0;
var next = 1;
result.AddState(start, false);
for (int i = 0; i < a.Length; ++i)
{
if (a[i] == '*')
{
result.AddTransition(next - 1, next - 1, NFA.Any);
}
else
{
result.AddState(next, false);
result.AddTransition(next - 1, next, (a[i] != '?' ? CharRange.SingleChar(a[i]) : NFA.Any));
++next;
}
}
result.AddState(next, true);
result.AddTransition(next - 1, next, NFA.Epsilon);
return(result);
}
public static NFA AnyOf(NFA left, NFA right)
{
var result = new NFA();
result.AddState(0, false);
result.AddTransition(0, result.Add(left), Epsilon);
result.AddTransition(0, result.Add(right), Epsilon);
return(result);
}
private int Add(NFA left)
{
int stateOffset = NewState();
foreach (var s in left.states)
{
AddState(s + stateOffset, left.final.Contains(s));
}
foreach (var t in left.transitions)
{
AddTransition(t.Item1 + stateOffset, t.Item2 + stateOffset, t.Item3);
}
return(stateOffset);
}
public static NFA Concat(NFA left, NFA right)
{
var result = new NFA();
result.Add(left);
var leftFinals = result.final.ToArray();
result.final.Clear();
int rightInitial = result.Add(right);
foreach (var final in leftFinals)
{
result.AddTransition(final, rightInitial, Epsilon);
}
return(result);
}
public static NFA Star(NFA input)
{
var result = new NFA();
var newFinal = result.NewState();
result.AddState(newFinal, true);
var start = result.Add(input);
var finals = result.final.Where(h => h != newFinal).ToArray();
foreach (var final in finals)
{
result.AddTransition(final, start, Epsilon);
}
result.AddTransition(newFinal, start, Epsilon);
return(result);
}