[PATCH 3/3] libstdc++: Optimize std::regex_traits lookup functions

[Jonathan Wakely]

On Tue, 10 Feb 2026 at 14:07, Tomasz Kaminski <tkaminsk@redhat.com> wrote:
>>
>> +       {
>> +       case 'a':
>> +         if (__read_ch() == 'l')
>> +           switch (__read_ch())
>> +             {
>> +             case 'n':
>> +               if (__match("um"))
>
> I think adding comments like if (__match("um"))  // alnum, would really
> help here.  I think they really helps for this two cases, but would
> add them everywhere...
>>
>> +                 return ctype_base::alnum;
>> +               break;
>> +             case 'p':
>> +               if (__match("ha"))
>>
>> +                 return ctype_base::alpha;
>> +               break;
>> +             }
>> +         break;
>> +       case 'b':
>> +         if (__match("lank"))
>> +           return ctype_base::blank;
>> +         break;
>> +       case 'c':
>> +         if (__match("ntrl"))
>> +           return ctype_base::cntrl;
>> +         break;
>> +       case 'd':
>> +         if (__first == __last || __match("igit"))
>
> And say // d or digit here.

Yes, this would be helpful. I'll add those comments.