Doesn't match simple evil case.

[RealAlphabet]

Evil regex : (a+?)(b+)

For example, with this as input : (a times 1000)zab

The number of steps increases exponentially.

[natrajms]

Yes. This has a bug. I tried the evil regex and found that it is not working. ^([a-zA-Z]+[,.]?[ ]?|[a-zA-Z]+['-]?)+$