Good String Tokenizer

[JamesHoward]

I have searched the board and noticed that there isn't really any sort
of good implementation of a string tokenizer that will tokenize based
on a custom set of tokens and return both the tokens and the parts
between the tokens.

For example, if I have the string:

"Hello, World!  How are you?"

And my splitting points are comma, and exclamation point then I would
expect to get back.

["Hello", ",", " World", "!", "  How are you?"]

Does anyone know of a tokenizer that will allow for this sort of use?

Thanks in advance,
Jim Howard