public static Automaton Repeat(Automaton a, int min, int max) { if (min > max) { return(BasicAutomata.MakeEmpty()); } max -= min; a.ExpandSingleton(); Automaton b; if (min == 0) { b = BasicAutomata.MakeEmptyString(); } else if (min == 1) { b = a.Clone(); } else { var @as = new List <Automaton>(); while (min-- > 0) { @as.Add(a); } b = Concatenate(@as); } if (max > 0) { var d = a.Clone(); while (--max > 0) { var c = a.Clone(); foreach (var p in c.GetAcceptStates()) { p.AddEpsilon(d.Initial); } d = c; } foreach (var p in b.GetAcceptStates()) { p.AddEpsilon(d.Initial); } b.IsDeterministic = false; b.ClearHashCode(); b.CheckMinimizeAlways(); } return(b); }