GNU bug report logs - #40868
Grep C library for multi-string pattern matching?

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jeffrey Walton <noloader <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: Grep C library for multi-string pattern matching?
Date: Sun, 26 Apr 2020 09:58:10 -0400

Hi Everyone,

I need to perform multi-string pattern matching in C. The problem I am
working on does not allow a shell script. I'm looking for a library
that implements Aho–Corasick or Commentz-Walter (or similar).

Does Grep provide a library that exposes its multi-string pattern
matching? If not, can someone recommend an implementation?

Thanks in advance.

Message #8 received at 40868 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: noloader <at> gmail.com
Cc: 40868 <at> debbugs.gnu.org
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Sun, 26 Apr 2020 12:19:40 -0700

On 4/26/20 6:58 AM, Jeffrey Walton wrote:

> Does Grep provide a library that exposes its multi-string pattern
> matching?

No, and that's partly by design: Grep is GPLed rather than LGPLed. I don't know
of any free library that does anything similar.

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Paul Jackson" <pj <at> usa.net>
To: bug-grep <at> gnu.org
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Sun, 26 Apr 2020 18:53:26 -0500

Perhaps you could use fork, exec, pipe, read, write, and similar system calls,
to execute grep and feed data through it, without resorting to any shell or
any shell wrapper such as the system(3) library call.

Or, if that would work, except for being rather fussy to code,
then consider Colin Watson's libpipeline:

  http://libpipeline.nongnu.org

-- 
                Paul Jackson
                pj <at> usa.net

Message #14 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Paul Jackson" <pj <at> usa.net>
To: bug-grep <at> gnu.org
Subject: Re: {SPAM 04.0} bug#40868: Grep C library for multi-string pattern matching?
Date: Sun, 26 Apr 2020 20:08:21 -0500

P.S. -- on multi-core systems (which most are these days),
piping data between executables working in parallel can
be a good way to reduce the elapsed clock time of a job,
albeit at the expense of higher system CPU utilization.

-- 
                Paul Jackson
                pj <at> usa.net

Message #17 received at 40868 <at> debbugs.gnu.org (full text, mbox):

From: Shlomi Fish <shlomif <at> shlomifish.org>
To: Jeffrey Walton <noloader <at> gmail.com>
Cc: 40868 <at> debbugs.gnu.org
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Mon, 27 Apr 2020 09:52:53 +0300

Hi Mr. Walton!

On Sun, 26 Apr 2020 09:58:10 -0400
Jeffrey Walton <noloader <at> gmail.com> wrote:

> Hi Everyone,
> 
> I need to perform multi-string pattern matching in C. The problem I am
> working on does not allow a shell script. I'm looking for a library
> that implements Aho–Corasick or Commentz-Walter (or similar).
> 
> Does Grep provide a library that exposes its multi-string pattern
> matching? If not, can someone recommend an implementation?
> 

There is an impl of Aho-Corasik in C++ here:
https://www.geeksforgeeks.org/aho-corasick-algorithm-pattern-searching/ (under
CC-by-sa).

Furthermore, you may wish to look at FOSS grep-like tools:

* https://wiki.freebsd.org/BSDgrep

* https://github.com/ggreer/the_silver_searcher

* https://beyondgrep.com/more-tools/

> Thanks in advance.
> 
> 
> 



-- 

Shlomi Fish       https://www.shlomifish.org/
Let’s talk about restores instead of backups - https://is.gd/WatQqu

“Stop reinventing wheels, start building space rockets.”
    — The motto of the Comprehensive Perl Archive Network

Please reply to list if it's a mailing list post - https://shlom.in/reply .

Message #20 received at 40868 <at> debbugs.gnu.org (full text, mbox):

From: Jeffrey Walton <noloader <at> gmail.com>
To: 40868 <at> debbugs.gnu.org
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Mon, 27 Apr 2020 11:12:53 -0400

On Sun, Apr 26, 2020 at 9:59 AM Jeffrey Walton <noloader <at> gmail.com> wrote:
>
> I need to perform multi-string pattern matching in C. The problem I am
> working on does not allow a shell script. I'm looking for a library
> that implements Aho–Corasick or Commentz-Walter (or similar).
>
> Does Grep provide a library that exposes its multi-string pattern
> matching? If not, can someone recommend an implementation?

Thanks everyone.

Message #25 received at 40868-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: noloader <at> gmail.com
Cc: 40868-done <at> debbugs.gnu.org
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Mon, 21 Sep 2020 12:28:28 -0700

Discussion on this old grep bug report has died down (and it wasn't a grep bug 
anyway) so I'm closing the bug report.

Message #28 received at 40868 <at> debbugs.gnu.org (full text, mbox):

From: Bruno Haible <bruno <at> clisp.org>
To: 40868 <at> debbugs.gnu.org, Jeffrey Walton <noloader <at> gmail.com>
Subject: Re: bug#40868: Grep C library for multi-string pattern matching?
Date: Tue, 22 Sep 2020 04:19:06 +0200

> Does Grep provide a library that exposes its multi-string pattern
> matching? If not, can someone recommend an implementation?

I don't know exactly what you mean, but the GNU grep algorithms are
used as a library in GNU gettext:
  https://git.savannah.gnu.org/gitweb/?p=gettext.git;a=tree;f=gettext-tools/libgrep

Although in hindsight, I don't know whether using simply a regex would not
have been just as good.

Bruno

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