#!/usr/bin/perl

use warnings;
use strict;
use Benchmark;

our @list = ('create the world','blah blah',
             'drop it already','foo schnerp',
             'need to delete','flip schnitzel',
             'send me that update!','a flibbertygibitz',
             'mailing insert collection','grand central station');

our @wordlist = qw(create drop delete update insert);
our @relist = map { qr/\b$_\b/ } @wordlist;
our $bigre_t = '\b(?:'.join('|',@wordlist).')\b';
our $bigre = qr/$bigre_t/;
print "bigre: $bigre\n";

sub several_re
{
  my $match = 0;
  foreach my $s (@list) {
    foreach my $re (@relist) {
      if ($s =~ /$re/) {
        $match++;
        last;
      }
    }
  }
  $match;
}

sub one_re
{
  my $match = 0;
  foreach my $s (@list) {
    if ($s =~ /$bigre/) {
      $match++;
    }
  }
  $match;
}

sub use_index
{
  my $match = 0;
  foreach my $s (@list) {
    foreach my $word (@wordlist) {
      if (index($s,$word) >= 0) {
        $match++;
        last;
      }
    }
  }
  $match;
}

print "several_re: ", several_re(),"\n";
print "one_re: ", one_re(),"\n";
print "use_index: ", use_index(),"\n";

timethese(100_000, {
  'Several Regexp' => \&several_re,
  'One Big Regexp' => \&one_re,
  'With index()'   => \&use_index,
});

##</code><code>##

Benchmark: timing 100000 iterations...
One Big Regexp:  7 wallclock secs (6.22 CPU) @ 16077.17/s (n=100000)
Several Regexp: 12 wallclock secs (11.27 CPU) @ 8873.11/s (n=100000)
With index(): 11 wallclock secs (8.71 CPU) @ 11481.06/s (n=100000)