Okay! Then my tabbed version of code ;-)

print <<HEAD;
------------------------------------
| id | name               | parent |
------------------------------------
HEAD

$idcount=0;
while (<DATA>) {
        # get rid of annoying tabs and \n
        chomp;
        s/^(\t*)//;

        # how many tabs?
        $tabs=length($1);

        # give it an id
        ++$idcount;

        # get the parent
        $parent=$parent[$tabs]+0;

        # set the parent
        $parent[$tabs+1]= $idcount;

        # print
        printf "| %2d | %-18s | %6d |\n",
                $idcount,
                $_,
                $parent;
}
print <<FOOT;
------------------------------------
FOOT

__END__
cat1
        cat1,sub1
                cat1,sub1,sub-sub1
        cat1,sub2
cat2
cat3
        cat3,sub1
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