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Re: [perl #124256] Regex loop for \K in lookbehind

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April 28, 2015 12:41
Re: [perl #124256] Regex loop for \K in lookbehind
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On 28 April 2015 at 13:14,  <> wrote:
> On Mon, 27 Apr 2015, James E Keenan via RT wrote:
>> > I think this is a similar bug to the one I have just
>> > fixed in PCRE.
>> >
>> Can you provide a link to that fix?
>> Thank you very much.
> Not very easily (I'd have to check the SVN manual to figure out how to
> search for stuff - I'm a very simple user) and in any case the fix was
> different for PCRE1 and PCRE2. The bug was in the test programs pcretest
> and pcre2test rather than in the library itself (which only does single
> matches). Here is a comment from pcre2test.c:
>     However, even after matching a non-empty string, there is still one
>     tricky case. If a pattern contains \K within a lookbehind assertion at the
>     start, the end of the matched string can be at the offset where the match
>     started. In the case of a normal /g iteration without special action, this
>     leads to a loop that keeps on returning the same substring.
> The code now checks for this case and advances the /g loop by one
> character, just as it does for matching an empty string.

Sounds like we have the same problem in Perl.

Karl, if you dont see a way to fix this then let me know and I will pick it up.


perl -Mre=debug -e "/just|another|perl|hacker/"

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