Bug #123645 for Regexp-Assemble: Incorrect handling of "x++x"

Thu Nov 16 09:15:41 2017 GUIDO [...] cpan.org - Ticket created

Subject:

Incorrect handling of "x++x"

Regexp::Assemble compiles "x++x" into /x+\+x/ but the second plus sign should not be escaped. The correct regex /x++x/ can never match, but /x+\+x/ matches for example "x+x" or "xxx+x". A similar problem exists for "x**x". That gets compiled into "x*\*x" which matches "whatever*x". But /x**x/ is syntactically wrong and should not match anything.

Mon Nov 20 17:51:48 2017 ron [...] savage.net.au - Correspondence added

Subject:	Re: [rt.cpan.org #123645] Incorrect handling of "x++x"
Date:	Tue, 21 Nov 2017 09:51:27 +1100
To:	bug-Regexp-Assemble [...] rt.cpan.org
From:	Ron Savage <ron [...] savage.net.au>

Hi Guido Did you try calling unroll_plus(1)? It might help. On 17/11/17 01:15, Guido Flohr via RT wrote: Show quoted text

> Thu Nov 16 09:15:41 2017: Request 123645 was acted upon. > Transaction: Ticket created by GUIDO > Queue: Regexp-Assemble > Subject: Incorrect handling of "x++x" > Broken in: 0.38 > Severity: (no value) > Owner: Nobody > Requestors: GUIDO@cpan.org > Status: new > Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=123645 > > > > Regexp::Assemble compiles "x++x" into /x+\+x/ but the second plus sign should not be escaped. > > The correct regex /x++x/ can never match, but /x+\+x/ matches for example "x+x" or "xxx+x". > > A similar problem exists for "x**x". That gets compiled into "x*\*x" which matches "whatever*x". But /x**x/ is syntactically wrong and should not match anything. >

-- Ron Savage - savage.net.au

Mon Nov 20 17:51:48 2017 The RT System itself - Status changed from 'new' to 'open'

Tue Nov 21 06:00:40 2017 GUIDO [...] cpan.org - Correspondence added

Sure, unroll_plus() may work. But it's disabled by default and that means that the default behavior is broken. I'm not using the module and am not affected by the problem. The question popped up, when I was commenting an answer on stackoverflow: https://stackoverflow.com/questions/47330247/predicting-proper-regular-expression-from-seeing-target-string/47330389#47330389 I used /x++x/ as an example of a regular expression that can never match, and later saw that Regexp::Assemble actually processed it incorrectly. So feel free to close the issue. It's mostly academic.

Thu Nov 23 16:42:38 2017 ron [...] savage.net.au - Correspondence added

Subject:	Re: ***SPAM*** [rt.cpan.org #123645] Incorrect handling of "x++x"
Date:	Fri, 24 Nov 2017 08:41:45 +1100
To:	bug-Regexp-Assemble [...] rt.cpan.org
From:	Ron Savage <ron [...] savage.net.au>

Hi Guido Thanx for the feedback. I plan to spend time in December finishing off my new module Regexp::Parsertron, which might offer a replacement for Regexp::Assemble. On 21/11/17 22:00, Guido Flohr via RT wrote: Show quoted text

> Queue: Regexp-Assemble > Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=123645 > > > Sure, unroll_plus() may work. But it's disabled by default and that means that the default behavior is broken. > > I'm not using the module and am not affected by the problem. The question popped up, when I was commenting an answer on stackoverflow: https://stackoverflow.com/questions/47330247/predicting-proper-regular-expression-from-seeing-target-string/47330389#47330389 > > I used /x++x/ as an example of a regular expression that can never match, and later saw that Regexp::Assemble actually processed it incorrectly. > > So feel free to close the issue. It's mostly academic. >

-- Ron Savage - savage.net.au

Wed Feb 07 21:45:37 2018 RSAVAGE [...] cpan.org - Correspondence added

Perhaps https://metacpan.org/release/Regexp-Parsertron will help in some way.