linux-kernel - Re: [PATCH] Make checkpatch rant about trailing ; at the end of "if" expr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 22 Aug 2007 11:57:24 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...putergmbh.de>
To:	Bodo Eggert <7eggert@....de>
cc:	Andy Whitcroft <apw@...dowen.org>,
	Eugene Teo <eugeneteo@...nel.sg>, linux-kernel@...r.kernel.org,
	auke-jan.h.kok@...el.com
Subject: Re: [PATCH] Make checkpatch rant about trailing ; at the end of "if"
  expr


On Aug 22 2007 11:21, Bodo Eggert wrote:
>
>> >> But. The above regex does not seem to handle
>> >> 
>> >> if ((a = b));
>> >> oops;
>> >> 
>> >> I have tried to come up with a superduper regex that handles multiple
>> >> (), but my regex fu seems to stop above two pairs of ().
>> >
>> >This is because you can't do that using finite regular expressions.
>> >
>> >Regular expressions are Type-3 grammars, but you'd need a Type-2
>> >grammar to express the Dyck language (and you need to parse a Dyck
>> >Language, ignoring the non-dyck-parts).
>> 
>> So what about this then...
>> 
>> $s = shift @ARGV;
>> $r = qr/a(??{ $r })?b/;
>
>This is not a regular expression, because it can't be parsed by a
>finite state machine (DFA/NFA) without a stack.
>http://en.wikipedia.org/wiki/Deterministic_finite_state_machine
>
>Obviously perl does allow non-regular expressions.

Exactly, and which is why my idea was to use a (??{ }) block to match if((()));
but for some reason, it did not fly, and I do not know either why.


	Jan
-- 
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/