22157RE: [Clip] A little help on look behinds
- Oct 16, 2011I found some fairly extensive explanations and examples of this and other such verbs in the PCRE text manual. Search for
commit to find all the bits.
From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of flo.gehrke
Sent: Sunday, October 16, 2011 05:33
Subject: Re: [Clip] A little help on look behinds
--- In email@example.com <mailto:ntb-clips%40yahoogroups.com> , Sheri <silvermoonwoman@...> wrote:
> (*COMMIT) says the rest of the pattern must match from here without
> backtracking...I guess you could say it creates an anchor in
> the middle of the pattern.
I would be grateful for some more explanations about that verb '(*COMMIT).
I've tested your clip...
against the following text which is quite similar to John's first sample. For our discussion, I've added line numbers
(to be removed when testing):
1 First line
3 [valid line]
5 ]]] remove
7 ]]] remove
9 [[[ valid line
10 more valid lines
11 ]]] valid line.
13 [[[ valid line
It's quite clear for me why the clip removes line #5 and #7 but not #9. But I still can't see why it doesn't remove line
If we omit the '\K' we can see two matches:
- 1. from start of string to end of line #5
- 2. line #6 till end of line #7
Next, line #8 and #9 are not matched because line #9 doesn't start with ']]]'.
But WHY doesn't the clip jump over that mismatch and moves on selecting line #10 and #11? IMHO, line #10 should be
matched with '(?s)\A.+?\R\K(?=\]\]\]|\[\[\[)' (with or without '\A'), and the following '(?-s)\]\]\].*\R'. Why on earth
is '(*COMMIT)' preventing this?
Thanks for any light you can shed on this!
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