On Wed, Jun 05, 2002 at 04:00:30PM -0400, Marcus J. Ranum wrote: > This is pretty cool!!! I think its a bit low-level for log > parsing but that may just be off the cuff without sufficient > thought. Down to the character level is probably too granular for log messages; I was just throwing that out as an example of the sort of grammar I'm discussing. > Left recursion was what scared me. I'm not sure you need it to do > left-to-right log parsing. Do you? If left recursion is omitted you > can play the trick I talked about in my first posting, where you make > the evaluator build a prefix tree. I don't think we should run into LR issues; if we do, there are some fairly trivial ways to rewrite a context-free grammar (the type we're discussing) to eliminate simple instances of left-recursion, and some other algorithms to eliminate all instances of it. (I think the Dragon book discusses this, and some guy at Microsoft recently wrote a document that summarizes the issue quite nicely and proposes some cool tricks to make the process of eliminating LR easier.) -- Sweth. -- Sweth Chandramouli Idiopathic Systems Consulting svcat_private http://www.idiopathic.net/ --------------------------------------------------------------------- To unsubscribe, e-mail: loganalysis-unsubscribeat_private For additional commands, e-mail: loganalysis-helpat_private
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