regular expression control

Hi all, I'm using regex with a list of regular expressions written by my team. They start from a set of rules and write down the expression (s). What I'm requested to do now is a function that given a regular expression write down all the combinations available, with some limitations of course: if for example an expression has an infinity of combination this could not be achieved. Since all the expression have a limited number of combinations in this case a warning will suffice. I searched for such a function in the regex code but didn't find it. Any idea? Thanks, Enrico