Notes Log » regular expression http://noteslog.com Sun, 05 Sep 2010 11:33:30 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 How to write a fast catch-all RegExp http://noteslog.com/post/how-to-write-a-fast-catch-all-regexp/ http://noteslog.com/post/how-to-write-a-fast-catch-all-regexp/#comments Sat, 17 May 2008 17:55:36 +0000 Andrea Ercolino http://noteslog.com/?p=208 In How to write a safe catch-all RegExp I suggested to use (?:\w|\W)* for matching any character in a regular expression. It’s certainly true and safe, and the same stands for its siblings (?:\s|\S)* and (?:\d|\D)*.

If you want to match a large text, these expressions are not the best. I’ve prepared a simple test page where the GeSHi’s engine file, which is almost 120KB, is going to be matched by the regular expression you input.

In Firefox 2 the performance is quite good, about 100 ms on my PC, but in Internet Explorer 7 it takes more than 7 minutes !!!

The best catch-all regular expression is [\w\W]*, which employs about 50 ms in FF2, and 0 ms in IE7 !!! (yes, zero milliseconds)

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