GNU bug report logs - #56079
Missing performance optimisation: Word start/end tests

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: sur-behoffski <sur_behoffski <at> grouse.com.au>
Cc: 56079 <at> debbugs.gnu.org
Subject: bug#56079: Missing performance optimisation: Word start/end tests
Date: Sun, 19 Jun 2022 10:26:43 -0500

On 6/19/22 00:38, sur-behoffski wrote:
>          a\<b
>          [abc]\>[def]
>
Yes, and this comes up even in strict POSIX without GNU extensions, as 
"a^" is a valid extended regular expression that cannot match anything.

I don't know whether dfa.c, regex.c, etc. optimize for this, but if not 
it would be nice if they did. For example, 'grep -E "a^" FOO' can 
silently exit with status 1 without even opening FOO.

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