in reply to Growing strings in search


You can't do it just using the perl regex engine. You might be able to turn your regex into a state machine, though, and then you could your strings through it character by character to find which one(s) match and which one(s) fail.

Building a state machine from a regex isn't *terribly* difficult, but there are a couple sticking points. The main problem is that you'll have a tradeoff of speed vs. memory consumption. For example, if your regex has branches and multiple capture groups in it, then you may have a *lot* of bookkeeping to track possible starts/stops of capture groups. You may be able to considerably simplify things by making your state machine simpler so it can recognize when a match happens but without tracking your capture groups, and then you can turn the normal perl regex engine loose on the full string to get your capture groups or do a more refined match.

I got distracted by your question and put together a simplified demo of the technique for fun. I'm still tuning it a little bit and I'll post it as a secondary reply later when I'm happy enough with it. If you post the regex you're using, I can tweak my demo accordingly.


When your only tool is a hammer, all problems look like your thumb.