my $rules = q{

                ^ <data_terminate> $

<token: data_terminate>
  (?: \.\x0D\x0A )


};

my $grammar = do {
    my $rule = "data_terminate";
    use re 'eval';
    use Regexp::Grammars;
    qr{$rules}xims;
};

if ( ".\x0D\x0A" =~ $grammar) {
    warn Dumper( \%/ );
}
else {
    say 'failed';
}