#! /usr/bin/perl

# ----------------------------------------------------------------
# John Kerl
# kerl.john.r@gmail.com
# 2000/11/03

# Replaces specified number of spaces with tabs, only for tabs not
# preceded by other characters.
# ----------------------------------------------------------------


$tab_width = 8;
if (@ARGV) {
	if ($ARGV[0] =~ m/^[\/-]/) {
		$tab_width = $ARGV[0];
		$tab_width =~ s/^.//;
		shift @ARGV;
	}
}

while ($line = <>) {
	chomp $line;
	my @chars = split //, $line;

	my $space_count = 0;

	while ((@chars > 0) && ($chars[0] eq " ")) {
		$space_count++;
		if ($space_count == $tab_width) {
			print "\t";
			$space_count = 0;
		}
		shift @chars;
	}

	for my $j (0 .. ($space_count - 1)) {
		print " ";
	}

	while (@chars) {
		print $chars[0];
		shift @chars;
	}
	print "\n";
}