Comments on: Regex Performance Optimization

By: Vimal

Vimal — Mon, 16 May 2011 09:25:39 +0000

Hi.. I need to optimise the following reg exp so that it executes faster. Can anyone help? Thanks ^([\d\w]{15}[\x01]\d{12}[\x01]\d{2}(.){6}((13((0[0-9]|([1-4][0-9])|5[0-9]))|14((0[0-9]|([1-2][0-9])|30)))[0-5][0-9])801(?:.*))$

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By: Shon

Shon — Mon, 10 Jan 2011 07:03:01 +0000

Hi found good contents on the blog,
i am new to regex and have one query about it.
Suppose if i have an expression (hello1) | (hello2) |(hello3)
Now on regex match i want to know which subexpression got matched, how can i get this information.

By: asd0z

asd0z — Mon, 10 May 2010 13:03:42 +0000

And what was other good material on the subject?

By: Cacycle

Cacycle — Sat, 01 Aug 2009 23:18:39 +0000

It can also help to "chew up" text that does not contain the matches inside the regExp itself. For example a regExp that searches for non-word matches in plain text: /(<|>|::|--|@|###)/ could be sped up by adding an additional chew-up blind-match: /(<|>|::|--|@|###)|[^<>:-@#]+/ The chew-up blind-match has then to be filtered out (e.g. as an empty match). This also works for matches containing words: /\b(http:|ftp:|gopher:)/ becomes: /\b(http:|ftp:|gopher:)|\b[^:]{7,}/ I had a gigantic regExp to parse wiki code for syntax highlighting, consisting of "|"-separated subexpressions for all existing wiki codes. Just by adding a chew-up expression I cut the execution time in half (the code is for the Wikipedia editor wikEd and I was using JavaScript under Firefox 3.5).