GNU bug report logs - #36167
[PATCH] Replace manually crafted hex regexes with [[:xdigit:]]

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From: npostavs <at> gmail.com
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: mattiase <at> acm.org, eggert <at> cs.ucla.edu, 36167 <at> debbugs.gnu.org, Drew Adams <drew.adams <at> oracle.com>, hi-angel <at> yandex.ru
Subject: bug#36167: [PATCH] Replace manually crafted hex regexes with [[:xdigit:]]
Date: Tue, 11 Jun 2019 13:50:49 -0400

Eli Zaretskii <eliz <at> gnu.org> writes:

>> > [0-9A-Fa-f] still has one advantage: the reader, and the
>> > writer, know exactly which characters are included without looking it up.
                                                        ^^^^^^^^^^^^^^^^^^^^^
>> > - whether non-ascii digits are accepted

>  ‘[:digit:]’
>       This matches ‘0’ through ‘9’.  Thus, ‘[-+[:digit:]]’ matches any
>       digit, as well as ‘+’ and ‘-’.

> Is anything missing here?  Where did the question about non-ASCII
> digits come from, given this text?

It came from (a hypothetical) user who doesn't remember (or hasn't read)
the documentation.  The advantage of [0-9A-Fa-f] vs [[:xdigit:]] here is
similar to explicit comparison against (point-min) vs (bobp) that you
pointed out in #35967.

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