Acme script for adding/removing comments (from 9fans)

com

#!/usr/bin/env rc

fn f {
	n=$1
	if(! cat $f | cut -c1-$n | 9 grep -v '^[  ]+$' >/dev/null){
		x=`{f `{expr $n + 1}}
		echo '.'$"x
	}
}

f=/tmp/com.$pid
cat >$f

switch($%){
case *.go *.c
	c='//'
case *.tex
	c='%'
case *
	c='#'
}

# Remove comment?
if(cat $f | 9 grep '^[  ]*'$c' ' >/dev/null){
	cat $f | 9 sed 's|'$c' ||'
	rm $f
	exit
}

# Add comment.
s=`{f 1}
if(~ $#s 0)
	cat $f | 9 sed 's|^|'$c' |'
if not
	cat $f | 9 sed 's|^('$"s')|\1'$c' |'

rm $f