I wonder if this would be a good test to give a software developer candidate. Develop a regex matcher that matches a subset of the regex rules in your language of choice (without using regex abilities, of course).
I don't know, regexes have a lot of rules so you need to supply a reference, requiring them to remember it is overkill, not to mention some of those rules are pretty arcane.
A simple implementation of ?, +, * , [] and non-capturing, precedence-only () hardly needs a reference. Whether greedy vs non-greedy + / * are implemented doesn't really matter.
I will say that the problem is much easier if you have a good grounding in the basics of compilers, while that knowledge is not hugely useful very often. Any positive value as a test will come from correlation with interest in CS IMO.
