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bug#5393: control message for bug 5393
From: |
Lars Ingebrigtsen |
Subject: |
bug#5393: control message for bug 5393 |
Date: |
Thu, 27 Jun 2019 19:41:59 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
The original suggestion was:
---
I have attached a patch that enables you to
use lookaround assertion in regexp
with following syntax:
* Positive lookahead assertion
\(?=...\)
* Negative lookahead assertion
\(?!...\)
* Positive lookbehind assertion
\(?<=...\)
* Negative lookbehind assertion
\(?<!...\)
Basically, it works as same as Perl's one.
Spec:
* Any pattern is allowed in lookahead assertion.
* Nested looaround assertion is allowed.
* Capturing is allowed only in positive lookahead/lookbehind assertion.
* Duplication is allowed after such assertion.
* Variable length pattern is NOT yet allowed in lookbehind assertion.
[x] \(?<=[0-9]+\)MB
[o] \(?<=[0-9][0-9][0-9][0-9]\)MB
* Lookahead assertion over start bound is not allowed in re-search-backward.
(re-search-backward "\(?<=a\)b") for buffer "abca_|_b"
will seek to first "ab".
---
That looks pretty cool to me, but there was next to no discussion about
this at the time (2009), which is a bit odd...
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
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