grep library?

[Dmitry Olshansky]

27-Oct-2013 07:00, Andrei Alexandrescu пишет:
> Hello,
>
>
> A coworker implemented a system that spawns grep to rummage through a
> large log file. Apparently doing so is quite a bit faster than using a
> regex.
>

I would love to see how does the usage of regex looks like. Some numbers 
would be just awesome. If regex is std.regex then also see:
https://github.com/D-Programming-Language/phobos/pull/1553


> This is because grep is highly specialized and optimized. I was
> wondering if we could implement a grepping library that builds on
> regex's strengths and also grep's many optimization tricks:

If we talking D, then std.regex doesn't do Boyer-Moore search hence for 
patterns that start with 100% fixed prefix it must be a great deal 
slower. I'm using a ShiftOr search that has the benefit of being 
applicable to fairly large class of prefixes (but it does look at every 
byte).

There are also things a grep can do that in a general purpose library I 
felt are just too heavy. A dedicated grep module could spent more time 
on these tricks though knowing in advance that the input is going to be 
quite large.

> http://lists.freebsd.org/pipermail/freebsd-current/2010-August/019310.html
>
>
> Andrei


-- 
Dmitry Olshansky