// //int nextEdge = 0;
// var delayed = new Stack<Tuple<IFsmState, int>>();
// while (currState.IsFinal == false || pos == text.Length)
// {
// var visitedTransitions = new SortedSet<string>();
// var transitions = currState.Flatten(s => s.OutTransitions.Where(nt => nt.Condition.IsSigma).Select(x => x.To), tt => visitedTransitions.Add(tt.ToString()))
// .SelectMany(ct => ct.OutTransitions.Where(nt => !nt.Condition.IsSigma));
// delayed.Push(Tuple.Create(currState, pos));
// foreach (var transition in transitions)
// {
// bool edge = MatchEdge(text, pos, transition);
// if (edge)
// {
// currState = transition.To;
// pos++;
// break;
// }
// else
// {
// if (delayed.Count > 0)
// {
// var retState = delayed.Pop();
// currState = retState.Item1;
// pos = retState.Item2;
// //nextEdge = retState.Item3;
// }
// }
// }
// }
// return currState.IsFinal;
//}
private bool IsMatch(string text, ref int pos, ref IFsmState tmpState)
{
if (tmpState.IsFinal)
{
return(true);
}
var delayed = new Stack <(IFsmState fallbackState, int fallbackPos)>();
var backStates = new List <(int pos, int fallbackLimit, int fallbackCount)>();
//сохранять outtransitions, pos с которого откат и считать откаты.
// если кол-во откатов больше кол-ва outTransitions, false
while ((tmpState.IsFinal == false || pos != text.Length) && pos < text.Length)
{
if (tmpState.OutTransitions.Any(t => t.Condition.IsSigma))
{
delayed.Push((tmpState, pos));
}
var visitedTransitions = new SortedSet <string>();
var transitions = tmpState.Flatten(
s => s.OutTransitions.Where(nt => nt.Condition.IsSigma).Select(x => x.To),
tt => visitedTransitions.Add(tt.ToString())
).SelectMany(ct => ct.OutTransitions.Where(nt => !nt.Condition.IsSigma));
bool succ = false;
foreach (var transition in transitions)
{
bool edge = this.MatchEdge(text, pos, transition);
if (edge)
{
tmpState = transition.To;
pos++;
succ = true;
break;
}
}
if (!succ)
{
if (backStates.Count == 0 || backStates.Last().pos != pos)
{
backStates.Add((pos, tmpState.OutTransitions.Count, 1));
}
else
{
var last = backStates.Last();
if (last.fallbackLimit < last.fallbackCount)
{
break;
}
else
{
var count = last.fallbackCount;
count++;
backStates.Remove(backStates.Last());
backStates.Add((last.pos, last.fallbackLimit, count));
}
}
var backState = delayed.Pop();
tmpState = backState.fallbackState;
pos = backState.fallbackPos;
}
}
return(tmpState.IsFinal);
}