Look ahead & look behind

kamanza · 11-08-2011, 06:18 AM

I've tried to use look ahead & look behind regex's in Sigil Find dialog like:

 (?=[a-z]) or (?<!\.)

but they did not work for me.
Also expressions like
.*? or \s*? do not seem to work.
Is there a way to make them work?
I would very much appreciate any help wit this.

user_none · 11-08-2011, 06:56 AM

0.4.x does not support look ahead or look behind. This is a limitation of QRegExp that Sigil uses. 0.5 (no release date yet) changes to using PCRE and supports look ahead and behind expressions.

kamanza · 11-08-2011, 01:06 PM

Thanks for the speedy answer, but i was wrong.
I've just manageed to correct all the broken lines with:



(?=[a-z])

replaced with nothing. Only somehow this doesn't always work. I had to write, then clear, then write the code again a few times until it eventually did the job.
I wander, why is it like that?

ldolse · 11-10-2011, 02:48 AM

Yeah, I'm pretty sure I've successfully used lookahead/lookbehind too. But overall I find Sigil's regex quite weird, so looking forward to PCRE.

As far as .*? or \s*? goes, the trick seems to be to never use the question mark, and to check the 'minimal matching' checkbox under the regex options - the makes all */+ act as if there is a question mark.

user_none · 11-10-2011, 06:41 AM

Quote:

Originally Posted by ldolse

Yeah, I'm pretty sure I've successfully used lookahead/lookbehind too.

My mistake. QRegExp supports lookahead. It's look behind it doesn't support.

11-08-2011, 06:18 AM	#1
kamanza Zealot Posts: 115 Karma: 10 Join Date: Jan 2011 Device: none	Look ahead & look behind I've tried to use look ahead & look behind regex's in Sigil Find dialog like: <p/> <p>(?=[a-z]) or (?<!\.)<p/> but they did not work for me. Also expressions like .? or \s? do not seem to work. Is there a way to make them work? I would very much appreciate any help wit this.

11-08-2011, 01:06 PM	#3
kamanza Zealot Posts: 115 Karma: 10 Join Date: Jan 2011 Device: none	Thanks for the speedy answer, but i was wrong. I've just manageed to correct all the broken lines with: </p> <p>(?=[a-z]) replaced with nothing. Only somehow this doesn't always work. I had to write, then clear, then write the code again a few times until it eventually did the job. I wander, why is it like that?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
The Road Ahead	borisb	enTourage Archive	17	04-06-2011 09:48 PM
PRS-950 Infrequent jumps ahead??	petercreasey	Sony Reader	4	03-26-2011 05:41 PM
Skipping ahead / Index	LucentBeam	Amazon Kindle	5	10-28-2010 09:08 PM
Wait or go ahead?	julon2000	Which one should I buy?	19	03-13-2009 10:13 PM
went ahead and got a 505	sigma8	Which one should I buy?	0	02-26-2009 11:38 AM

11-08-2011, 06:56 AM	#2
user_none Sigil & calibre developer Posts: 2,487 Karma: 1063785 Join Date: Jan 2009 Location: Florida, USA Device: Nook STR	0.4.x does not support look ahead or look behind. This is a limitation of QRegExp that Sigil uses. 0.5 (no release date yet) changes to using PCRE and supports look ahead and behind expressions.

11-10-2011, 02:48 AM	#4
ldolse Wizard Posts: 1,337 Karma: 123455 Join Date: Apr 2009 Location: Malaysia Device: PRS-650, iPhone	Yeah, I'm pretty sure I've successfully used lookahead/lookbehind too. But overall I find Sigil's regex quite weird, so looking forward to PCRE. As far as .? or \s? goes, the trick seems to be to never use the question mark, and to check the 'minimal matching' checkbox under the regex options - the makes all */+ act as if there is a question mark.

Advert

Advert