Re: bug#26193: [0-9] versus [[:digit:]]

[Jim Meyering]

On Wed, Mar 22, 2017 at 2:58 PM, John P. Linderman <address@hidden> wrote:
> I used to use LC_ALL=C, but, as I vaguely recall, it got in the way of
> dealing with UNICODE. I tried a couple LC values aimed at UNICODE and the
> US, but something always went pear-shaped. I finally give up. I am perfectly
> happy to suffer a tiny bit of performance, to have most things work without
> thinking. A factor of 6, or 35, is not tiny, since I use grep and friends
> intensely. That's how I discovered the performance problem to begin with.
> Anyway, thank you for fixing my problem. I suspect that many of us pioneers
> (using UNIX since 1973) have '[0-9]' wired into our fingers.
>
> On Wed, Mar 22, 2017 at 2:01 PM, Paul Eggert <address@hidden> wrote:
>>
>> On 03/22/2017 05:44 AM, John P. Linderman wrote:
>>>
>>> That puts the runtimes on equal footing:
>>>
>> In my measurements, P[0-9] is still a tiny bit slower if one is using
>> glibc regex, due to a performance problem in glibc. You can work around it
>> by configuring --with-included-regex. It's probably not worth worrying
>> about, though.
>>
>> By the way, using LC_ALL=C should help avoid performance problems like
>> these in the future, if all you're doing is something where single-byte
>> pattern matching suffices.

I've just pulled that gnulib change into grep's repository with the
attached, along with a NEWS update:

grep-gnulib-dfa-NEWS.diff
Description: Text document