How do I test against a large number of regular expressions quickly and know which one matched?

Posted by Jack on Stack Overflow See other posts from Stack Overflow or by Jack
Published on 2010-05-24T19:48:08Z Indexed on 2010/05/24 19:51 UTC
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regex

I'm writing a program in .net where the user may provide a large number of regular expressions. For a given string, I need to figure out which regular expression matches that string (if more than one matches, I just need the first one that matches). However, if there are a large number of regular expressions this operation can take a very long time.

I was somewhat hoping there would be something similar to flex for .net that would allow me to specify a large number of regular expressions yet quickly (O(n) according to Wikipedia for n = len(input string)) figure out which regular expression matches.

Also, I would prefer not to implement my own regular expression engine :).

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