Hi Martijn, It's not that tricky if you do a regular expression state machine yourself, but that's probably a bit too much work. One way to get a speed up might be to take the regular expressions a,b,c,d and generate a regex a+b+c+d, and one a+b. You can then check any string s against a+b+c+d, if that matches check a+b, if that matches check a. At each stage you eliminate half the regular expressions, which means a match will take log n, where n is the number of regular expressions. This assumes the underlying regular expression engine constructs a finite state machine, making it O(m) where m is the length of the string to match. Thanks Neil
-----Original Message----- From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Martijn van Steenbergen Sent: 04 November 2008 5:05 pm To: Haskell Cafe Subject: [Haskell-cafe] Efficient parallel regular expressions
Hello all,
For my mud client Yogurt (see hackage) I'm currently working on improving the efficiency of the hooks. Right now several hooks, each consisting of a regex and an action can be active at the same time. Every time a line of input is available (usually several times a second) I run the line through all the available regexes and execute the first matching action.
I figured this is not the cleverest approach and it'd be better if I |'ed all regexes into one big DFA. However, how do I then find out which of the original hooks matched and so which action to execute?
As far as I know there's no way to do that with Text.Regex. Alex looks promising but is really only an executable and doesn't offer an API. I've also found mr. João Saraiva's HaLex but I don't know if that was meant to be used seriously.
Does anyone have any experience with this? What's the best way to achieve this?
Thanks much,
Martijn.
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ==============================================================================