/// <summary>
/// Returns a regex that accepts the complement of this regex.
/// </summary>
/// <param name="regex">this regex</param>
/// <param name="timeout">timeout to complement in ms</param>
/// <returns></returns>
public static Regex Complement(this Regex regex, int timeout = 10000)
{
var solver = new CharSetSolver();
var aut = solver.Convert(regex.ToString(), regex.Options).RemoveEpsilons();
var aut_det = aut.Determinize(timeout);
var aut_min_c = aut_det.Minimize().Complement();
var pattern = solver.ConvertToRegex(aut_min_c);
return(new Regex(pattern, regex.Options));
}
