Re^2: Perl regex limitations (32k)

Warnings enabled, the 32k problem should have manifested itself:

Complex regular subexpression recursion limit (32766) exceeded

To work around this problem (a warning remains), one may double the repeat quantifiers, e.g.:

my $braces = qr/(?<braces> { (?: (?: [^{}] | (?&braces) )*+ )* } )/x;
[download]

perlre has the following example on handling nested parens:

my $parens = qr/(\((?:[^()]++|(?-1))*+\))/;
if (/foo $parens \s+ \+ \s+ bar $parens/x) {
   # do something here...
}
[download]

Comment on Re^2: Perl regex limitations (32k) Select or Download Code

Replies are listed 'Best First'.
Re^3: Perl regex limitations (32k) by jonneve (Initiate) on Aug 06, 2014 at 13:20 UTC
Thanks for all the replies! I tried adding the following test to see if I can get it working (as I said, I have now rewritten it to do the parsing by hand, but I would like to figure it out for next time): `$braces = qr/(?<braces>\{ ([^\{\}]++ \| (?&braces))+ \} )/x; if ($h =~ s/class \s+ (?<class_name> \w+) \s (\: (\s* \w)? \s (?<an +cestor> \w+))? \s* $braces//x) { print "hi\n"; }` [download] The match is never made however... The code I'm matching against is a C++ header file, and I'm looking for class definitions, formatted like this : `class MyClassName : public MyAncestorClass { ... ... };` [download] This expression works fine for smaller classes or for this same problem class if there are no braces inside the class definition. In this class however, I have the following declarations (C++ Builder code...) : `__property TNotifyEvent OnMonaDocSaveToDB = {read=FOnMonaDocSaveToDB +, write=FOnMonaDocSaveToDB};` [download] If I remove that property declaration, it matches, if I leave it, it fails... Jonathan	[reply] [d/l] [select]
Re^3: Perl regex limitations (32k) by jonneve (Initiate) on Aug 06, 2014 at 14:03 UTC
I just checked, there is no warning when I execute my script using "perl -w"...	[reply]
Re^4: Perl regex limitations by Anonymous Monk on Aug 06, 2014 at 16:08 UTC
On the off chance that you've stumbled upon an undiscovered bug, the considerate route to take is to provide a testcase. This may involve some tedious work reducing a self-contained test unit to a minimum. That, of course, after you've verified the behavior with the latest perl.	[reply]