regular expression negate a word (not character)

[Dr.Ruud]

Greg Bacon schreef:

> #! /usr/bin/perl
> 
> use warnings;
> use strict;
> 
> use constant {
>   MATCH    => 1,
>   NO_MATCH => 0,
> };
> 
> my @tests = (
>   [ "winter tire",                => MATCH ],
>   [ "tire",                       => MATCH ],
>   [ "retire",                     => MATCH ],
>   [ "tired",                      => MATCH ],
>   [ "snowbird tire",              => MATCH ],
>   [ "tired on a snow day",        => MATCH ],
>   [ "snow tire and regular tire", => MATCH ],
>   [ " tire"                       => MATCH ],
>   [ "snow tire"                   => NO_MATCH ],
>   [ "snow   tire"                 => NO_MATCH ],
>   [ "some snowtires"              => NO_MATCH ],
> );
> [...]

I negated the test, to make the regex simpler:

my $snow_tire = qr/
 snow [[:blank:]]* tire (?!.*tire)
/x;

my $fail;
for (@tests) {
  my($str,$want) = @$_;
  my $got = $str !~ /$snow_tire/;
  my $pass = !!$want == !!$got;

  print "$str: ", ($pass ? "PASS" : "FAIL"), "\n";

  ++$fail unless $pass;
}

print "\n", (!$fail ? "PASS" : "FAIL"), "\n";

__END__

-- 
Affijn, Ruud

"Gewoon is een tijger."