GNU bug report logs - #18762
[PATCH] dfa: don't consider RE_DOT_NEWLINE and RE_DOT_NOT_NULL in matching with a bracket expression

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Message #17 received at 18762 <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: Jim Meyering <jim <at> meyering.net>
Cc: 18762 <at> debbugs.gnu.org
Subject: Re: bug#18762: [PATCH] dfa: don't consider RE_DOT_NEWLINE and
 RE_DOT_NOT_NULL in matching with a bracket expression
Date: Sun, 19 Oct 2014 11:07:52 +0900

[Message part 1 (text/plain, inline)]

Jim Meyering <jim <at> meyering.net> wrote:
> dfa.c's match_mb_charset function *is* used, e.g., in a
> command like this one:
> 
>   printf '\0' |src/grep -aE '^\s?$'

Wow, just it isn't good.  I think that behavior of `fails' should be
same as of `trans' except `fails' checks accepted conditions, including
following part.  match_mb_charset() should be avoided as far as possible,
as it doesn't support collating symbols and equivalence classes.

>               /* Falling back to the glibc matcher in this case gives
>                  better performance (up to 25% better on [a-z], for
>                  example) and enables support for collating symbols and
>                  equivalence classes.  */
>               if (d->states[s].has_mbcset && backref)
>                 {
>                   *backref = 1;
>                   goto done;
>                 }

[0001-dfa-fall-MBCSET-back-to-the-glibc-matcher-in-transit.patch (text/plain, attachment)]

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