in reply to Are Perl patterns universal?

We can also craft patterns that loop forever (not merely a long time) (well, ignoring stack overflows that is) 

#Word boundries are zero-width so the regex engine will never progress

my $inf; $inf=qr/\b(??{$inf})/;

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Did you try it? See perlre/Repeated patterns matching zero-length substring

Currently, you can mis-use \G to loop forever: 1 while "a" =~ /a|\G/g. Doesn't work in a single list-context ()="a"=~/a|\G/g though.

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Re^2: Are Perl patterns universal?
by sleepingsquirrel (Chaplain) on Nov 09, 2004 at 03:30 UTC
    Did you try it?
    running this program... 
    my $inf; $inf=qr/\b(??{$inf})/;
print "matched" if ("abc"=~m/$inf/);

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    ...under perl5.8.4 results in a "Segmentation fault" on my machine.

    -- All code is 100% tested and functional unless otherwise noted.
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