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Postings from August 2016
On Sat Aug 06 14:10:37 2016, aab@purdue.edu wrote:
> This is a comment and a possible suggestion.
>
>
> I've been playing around (read a LOT of hacking) with the CPAN
> "JavaScript::Beautifier" module to increase its performance and
> completeness. In one part of its 'get_next_token()' sub, it extracts
> quoted strings. I swiped the (first encountered) perlre(1) example
>
> /"(?:[^"\\]++|\\.)*+"/
>
> as the basis for the regex pattern to use. Unfortunately, during my
> testing, I found a javascript file,
> https://github.com/ternjs/acorn/blob/master/test/jquery-string.js,
> that causes that dread "Complex regular subexpression recursion limit"
> error message.
I am surprised. I thought the ++ would avoid that.
> I next tried variations of the second example
>
> /"(?>(?:(?>[^"\\]+)|\\.)*)"/
>
> with the same result. FWIW - the opening quote in the 'jquery-
> string.js' file is on the first line, the closing quote is on last
> line, 10314 lines later, and the file is full of \" .
>
>
> I ended up using the regex expression
>
> /\G((?>$peek.*?(?<!\\)$peek))/s
>
> where $peek is the quote character. It seems to work fine but I'll
> bet that there are probably a bunch of "gotchas" that I haven't
> encountered yet.
Such as this code snippet:
alert("\\" + "\\");
In a browser, that pops up an alert message with two backslashes. If I run your regular expression on it without the \G:
$peek = '"';
<<\ENd =~ /((?>$peek.*?(?<!\\)$peek))/s;
alert("\\" + "\\");
ENd
print "$1\n";
__END__
it gives me:
"\\" + "
FWIW, JE uses:
/\G (?: '([^'\\]*(?:\\.[^'\\]*)*)'
|
"([^"\\]*(?:\\.[^"\\]*)*)" )/xcgs
The basic pattern is:
normal* ( special normal* )*
--
Father Chrysostomos
---
via perlbug: queue: perl5 status: new
https://rt.perl.org/Ticket/Display.html?id=128864
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