perlquestion
kimmel
<p>Okay I am trying to figure out why 'one' works but 'two' just hangs the script. I read perlre and perlretut again to see if the answer would just jump out at me and it didn't.</p>
<p><b>Edit: I forgot to paste part of the code below. See my follow-up comment for the correct full program.</b></p>
<code>
#!/usr/bin/perl
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;
cmpthese(
-5,
{
'one' => sub {
$seen{$1}++ while $content =~ /$regex/g;
},
'two' => sub {
$seen2{$1}++ while $content =~ /$regex/;
},
}
);
</code>
<p>
The source text is Bram Stoker's Dracula a 836KB file with 16,248 lines. The sample_patterns file contains 4,000 patterns, one per line. The only difference between 'one' and 'two' is the g modifier on the regexp.
</p>