Why convert it, when you can easily just change it to a set of if statements and eval that?

Note, completely untested code, written from memory

if($_ =~ s/\[(\d+)-(\d+)\]/){
s/\[(\d+)-(\d+)\]/command if(\$x >= $1 && \$x <= $2);/;
eval $_;
}
[download]

Most likely this code won't compile, but it's a starting point.