# vim: ft=zsh noet
local target die_msg re edscript
target=$1
if [[ $2 == '!' ]]; then
	shift 2
	re=$1
	edscript=$2$'\nw\n'
	die_msg="failed to edit file ${target:t} to not match ${(qqq)re}"
	if grep -q $re $target; then
		ed -s $target <<<$edscript  # || die $die_msg
		grep -q $re $target && die $die_msg
	fi
else
	shift
	re=$1
	edscript=$2$'\nw\n'
	die_msg="failed to edit file ${target:t} to match ${(qqq)re}"
	if ! grep -q $re $target; then
		ed -s $target <<<$edscript  # || die $die_msg
		grep -q $re $target || die $die_msg
	fi
fi