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Re: Regexp::Assemble hangs with a certain case

by Anonymous Monk
on Nov 16, 2012 at 03:18 UTC ( #1004110=note: print w/replies, xml ) Need Help??

in reply to Regexp::Assemble hangs with a certain case

Run this

perl -Mre=debug -le " 1 while q{234} =~ /\d/g "

Compare with one or two pages from this infinite loop

perl -Mre=debug -le " 1 while q{234} =~ /\d/ "

You should notice that without g in m//g the pos-ition doesn't advance, you're always matching against 2, and its always true, and it never ends, cause 2 is always \d

Regexp::Assemble hangs with a certain case

A regex produced by Regexp::Assemble is not Regexp::Assemble , Regexp::Assemble is not hanging -- but you're not even using Regexp::Assemble to assemble a regex, so its got nothing to do with it

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Re^2: Regexp::Assemble hangs with a certain case
by kimmel (Scribe) on Nov 16, 2012 at 17:20 UTC

    Ooops I did not check the code I posted, again. I really need to stop doing that. Here is what the program should have looked like.

    use v5.16; use warnings; use autodie qw( :all ); use utf8::all; use File::Slurp qw( read_file ); use Regexp::Assemble; use Benchmark qw( cmpthese :hireswallclock ); my %seen; my %seen2; my $fname = 'dracula.txt'; my $content = read_file($fname); $content =~ tr/!"#$%&'()*+,\-.\/:;<=>?@\[\\]^_`{|}~/ /; my @patterns = read_file('sample_patterns'); chomp @patterns; my $regex = join '|', map {quotemeta} @patterns; $regex = qr/\b($regex)\b/ixms; my $regex2 = Regexp::Assemble->new->add(@patterns); $regex2->anchor_word(1); $regex2->flags('ixms'); $regex2->re(); cmpthese( -5, { 'one' => sub { $seen{$1}++ while $content =~ /$regex/g; }, 'two' => sub { $seen2{$regex2->mvar(1)}++ while $content =~ /$regex2/; }, } );

    I understand now why it was acting the way it was.

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