sub inclusive {
  my ($big, $little) = @_;
  $big =~ join(
    '',
    map { "(?=.*" . join('.*', @$_) . ")" }
    map { ++$i & 1 ? [ map quotemeta, split // ] : () }
    join('', sort split //, $little) =~ /((.)\2*)/gs;
  );
}

##</code><code>##

sub inclusive {
  ($chunk, $word) = @_;  # sorry, no 'my' here
  my $r;
  $r = qr{
    (??{ "[^\Q$word\E]*" })
    ((??{ "[\Q$word\E]" }))
    (?{ substr($word, index($word,$1), 1) = "" })
    (?(?{ length $word })(??{ $r }))
    |
    (?!)
  }x;
  scalar $chunk =~ $r;
}