I have an odd problem that's hurting my head: I'm trying to construct an RE that will only match if the letter in any position does *NOT* match any other character in the string. I'm constructing this RE with a perl program and building the RE from a template. It is the *template* that says "these letters should be distinct" and then I want to run through a few thousand words to pick out the words that "match".
For example, my "template" might look like this: "abcdefa" and I already have the code that generates (.)?????\1. I can't figure how to make the "?"s say "these guys all have to be distinct".