cutv

#!/usr/bin/perl -w

use strict;
use Getopt::Std;

our($opt_l, $opt_d, $opt_f);

$opt_d='^\s*$';
getopt('ldf');

$opt_d = eval { qr/$opt_d/ };
die "invalid regexp for -d: $@" if $@;

for($opt_f, $opt_l) {
    $_ = [sort {$a <=> $b} split(/,/, $_)] if ($_);
}

my $l_idx;
my $l_next;
if ($opt_l) {
    $l_idx=0; $l_next=$$opt_l[0];
}
my $f_idx;
my $f_next;
if ($opt_f) {
    $f_idx=0; $f_next=$$opt_f[0];
}

my $ln=1;
my $fn=1;
while (<STDIN>) {
    my $on_sep = /$opt_d/;
    if (defined($l_idx) and $ln==$l_next) {
        print;
        ++$l_idx;
        if ($l_idx <= $#$opt_l) {
            $l_next = $$opt_l[$l_idx];
        } else {
            $l_idx = undef;
        }
    } elsif (defined($f_idx) and $fn==$f_next and !$on_sep) {
        print;
    }

    if ($on_sep) {
        if (defined($f_idx) and $fn==$f_next) {
            ++$f_idx;
            if ($f_idx <= $#$opt_f) {
                $f_next = $$opt_f[$f_idx];
            } else {
                $f_idx = undef;
            }
        }
        ++$fn;
    }

    ++$ln;
}


# TODO: multi-line delimiters
# TODO: start and end delimiters