I suggest using here-docs for grammars.

#!perl
use warnings;
use strict;

my $one = q{/\d \\ \/ \\/ /
};
my $two = <<'--snip--';
/\d \\ \/ \\/ /
--snip--

print "\$one is `$one'\n\$two is `$two'\n";
__END__
[download]

This prints

$one is `/\d \ \/ \/ /
'
$two is `/\d \\ \/ \\/ /
'
[download]

which means you needn't escape your backslashes in single-quote here-docs. This can make regexes more readable.