Re^2: Analyzing regular expression performance

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Re^3: Analyzing regular expression performance by Sprad (Hermit) on May 12, 2006 at 16:54 UTC
Changing the `$sp` regex to `(?:\s*)` cut runtime to almost nothing, so it looks like that's where my problem is. I do need to allow comments anywhere in the string, though -- including having comments right after comments. Is there a cleaner way of doing that? --- A fair fight is a sign of poor planning.	[reply] [d/l] [select]
Re^4: Analyzing regular expression performance by grinder (Bishop) on May 12, 2006 at 19:04 UTC
I do think you are insane to parse SQL with regular expressions, but if you are brave and insist on this approach, I would suggest a multi-pass approach. Write one pattern that strips out comments. Write another pattern to coalesce blanks into a single blank. Then you will find that writing a third pattern to pick apart an expression becomes much easier. At least you won't need so many nested 0-or-many groupings -- that is what is killing your performance. I tried to run your code and it ate up all available memory... I do no think this approach will scale. • another intruder with the mooring in the heart of the Perl	[reply]