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Answer 1

+1 A:

It's harder to write a regex to match for things you don't want then to match the things you do want. Usually when I run into this situation, I find it easier and faster to do things in two steps. In this case, I'd probably find all events that do contains FREQ=, remove those events, then continue matching on the result for the start and end times I want. Could you post the regex you tried with !?, because maybe it's easy to fix... Also, I assume this is in Objective-C, and I'm guessing the environment you're using does support !? (but not all of them do)...

UPDATE

Ok, try this one:

BEGIN:VEVENT.+?
(?<!FREQ=.+)DTSTART;.+?([0-9]{8})T([0-9]{6})
DTEND;.+?([0-9]{8})T([0-9]{6}).+?
END:VEVENT

FrustratedWithFormsDesigner 2010-08-06 15:25:24

Line 1 changes to `BEGIN:VEVENT.+?(!?FREQ=).+?` when I tried with the !? operator. I am using PHP, but it should be PCRE compatible with a / before and after with an s option after the second I think.

Josh 2010-08-06 15:30:54

@Josh: Added modified regex. Works for me in Expresso but Expresso is .NET-based and I don't have a PHP test environment

FrustratedWithFormsDesigner 2010-08-06 16:00:52

Nice work. That works perfectly. Thank you!

Josh 2010-08-06 16:24:36

I jumped too soon, I get a variable length lookbehind assertion error with PHP. Apparently look-behinds have to be fixed length in PHP. I was using a RegEx Engine for design that also apparently relied on .NET.

Josh 2010-08-06 16:47:11

@Josh: so... which expression did you end up using?

FrustratedWithFormsDesigner 2010-08-06 16:58:42

I ended up doing a capture on all data between the start and end tags, and when I got to using the data I did a quick search to detect `FREQ` in the capture. It's a two step process, and less elegant, but I guess it works. I had some success with doing conditionals, but the PHP PCRE engine is apparently picky about those as well.

Josh 2010-08-06 17:44:46

Answer 2

A:

Why not use a PHP iCalendar parser?

http://www.phpclasses.org/browse/file/16660.html

Doug 2010-08-12 18:16:20

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