use Test::More tests => 1;
use Data::Dumper;
'cow' =~ /
  (?:
    # Grammar rules go here...
    (?<thing> .+ )
  ){0}

  # Invoke grammar here
  ^(?&thing)
/x
  or die "Didn't match";

my $got = Dumper({
    '%+' => {%+},
    '@+' => [@+],
    '@-' => [@-],
});
my $expected = Dumper({
    '%+' => {
        thing => 'cow'
    },
    '@-' => [ 0, 0 ],
    '@+' => [ 3, 3 ],
});
is( $got, $expected );