bug#36167: [PATCH] Replace manually crafted hex regexes with [[:xdigit:]]

[Andy Moreton]

On Tue 11 Jun 2019, Eli Zaretskii wrote:

>> Date: Tue, 11 Jun 2019 10:19:17 -0700 (PDT)
>> From: Drew Adams <drew.adams@oracle.com>
>> Cc: mattiase@acm.org, eggert@cs.ucla.edu, 36167@debbugs.gnu.org,
>>         hi-angel@yandex.ru
>> 
>> > Isn't it clear already?
>> 
>> I meant [:xdigit:], not [:digit:], in my reply.  Sorry for
>> the typo.
>
> :xdigit: is also clearly documented:
>
>   ‘[:xdigit:]’
>        This matches the hexadecimal digits: ‘0’ through ‘9’, ‘a’ through
>        ‘f’ and ‘A’ through ‘F’.

The docs for [:digit:] and [:xdigit:] seem clear enough, but there is
one other minor point that could be clarified.

The [:alnum:] and [:alpha:] are based on (unspecified values of) the Unicode
general-category property, but [:digit:] is not. Thus [:alnum:] includes
other numeric characters that are not matched by [:digit:].

    AndyM