private static void AddState(RegexState state, ISet<RegexState> stateSet)
{
stateSet.Add(state);
foreach (var eps in state.Epsilon) {
AddState(eps, stateSet);
}
}
private void HandleAlt(Token token)
{
var n2 = _regexStack.Pop();
var n1 = _regexStack.Pop();
var s0 = new RegexState();
s0.Epsilon.Add(n1.Start);
s0.Epsilon.Add(n2.Start);
var s3 = new RegexState();
n1.End.Epsilon.Add(s3);
n2.End.Epsilon.Add(s3);
n1.End.IsFinalStates = false;
n2.End.IsFinalStates = false;
var regex = new Regex(s0, s3);
_regexStack.Push(regex);
}
private static void Draw(RegexState regexState, StringBuilder sb, HashSet<string> set)
{
if (set.Contains(regexState.ToString())) {
return;
}
set.Add(regexState.ToString());
if (!regexState.IsFinalStates) {
sb.Append($" {regexState} [shape=\"circle\"];\n");
}
foreach (var transition in regexState.Transitions) {
sb.Append($" {regexState} -> {transition.Value}[label=\"{transition.Key}\"];\n");
Draw(transition.Value, sb, set);
}
foreach (var state in regexState.Epsilon) {
sb.Append($" {regexState} -> {state}[label=\"ε\"];\n");
Draw(state, sb, set);
}
}
private void HandleChar(Token token)
{
var s0 = new RegexState();
var s1 = new RegexState();
s0.Transitions.Add(token.Text.First(), s1);
var regex = new Regex(s0, s1);
_regexStack.Push(regex);
}
private void HandleRepeat(Token token)
{
var s0 = _regexStack.Pop();
var s1 = new RegexState();
var s2 = new RegexState();
s1.Epsilon.Add(s0.Start);
if (token.Text == "*") {
s1.Epsilon.Add(s2);
}
s0.End.Epsilon.Add(s2);
s0.End.Epsilon.Add(s0.Start);
s0.End.IsFinalStates = false;
var regex = new Regex(s1, s2);
_regexStack.Push(regex);
}
public Regex(RegexState start, RegexState end)
{
Start = start;
End = end;
End.IsFinalStates = true;
}