my $tokens = "32,15,4,72,13,28,14";
my %code = do { my $i = 0; map { $_ => $i++ } split /,/, $tokens };

my $list = "4,13,15";
my $ok;
for my $token (sort { $code{$a} <=> $code{$b} } split /,/, $list) {
  print "$token ";
  # more code with $token...
  last if $ok;
}

__END__
15 4 13