GNU bug report logs - #16544
Optimazation for is_mb_middle

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: 16544 <at> debbugs.gnu.org
Subject: bug#16544: Optimazation for is_mb_middle
Date: Sat, 25 Jan 2014 11:39:11 +0900

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

Package: grep
Tags: patch

When matched characters to a regular expression is found by kwsexec or
dfaexec, we need check whether it is in the middle of a multi-byte character.

`is_mb_middle' of searchutils.c is used for it. However, it's expensive,
even if most of them contain constitute with single-byte characters.
For example, a source code written in a language with multibyte characters,
has a lot of single-byte characters.

Now, I post the patch which optimizes `is_mb_middle'. It checks whether
each single-byte is completion as an character before execution, and
caches them. In addition, for UTF-8 further optimization is performed.

Only when it's impossible to determine the length of a multibyte character
with caches, the length is determined with `mbrlen' in execution.

[is_mb_middle.txt (application/octet-stream, attachment)]

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