[Request] Text expanding tool

I have searched for many apps or tweaks to do that but I still haven't found any.

Basically, I would like a tweak that will automatically convert keyboard shortcuts into phrases.

For example, if you write "!hhh" it automatically changes to "hey how are you?". There is an app called Xpandr on Cydia for iphone and it does exactly that.

Is it possible for someone to develop an app like this that will work with the normal keyboard in any app / input box (even in browsers)?