add `$opt=-' syntax for setting a config opt to an empty value

`$opt=' was already being used for resetting an opt to its default
value.

1 files changed, 13 insertions, 6 deletions

diff --git a/backomp b/backomp
index aba6450..2aa873d 100755
--- a/backomp
+++ b/backomp
@@ -6,8 +6,8 @@ set -e
 function flr(n, s) { return int(n / s) * s }
 
 BEGIN {
-	split("h d w m", arr)
-	for (i = 1; i <= length(arr); ++i) {
+	len = split("h d w m", arr)
+	for (i = 1; i <= len; ++i) {
 		b = arr[i]
 
 		if (!match(retain, "([*0-9]+)" b, md))
@@ -64,8 +64,8 @@ run() {
 backup() {
 	dest_dir="${1}"
 	src_path="${2}"
-	retain="${3:-"*h*d*w*m"}"
-	replace="${4:-"h"}"
+	retain="${3}"
+	replace="${4}"
 
 	[[ "$((dcount++))" -ne 0 ]] && echo
 	echo "[${dcount}] [${retain}] ${src_path} => ${dest_dir}"
@@ -96,15 +96,22 @@ backup() {
 	printf 'kept %s\n' "${keep[@]}"
 }
 
+declare -A def_opts=(
+	['retain']='*h*d*w*m'
+	['replace']='h'
+)
 declare -A opts
+
 while IFS='=' read -r f1 f2; do
 	[[ -z "${f1}" ]] && continue
 
 	if [[ "${f1}" =~ ^\[(.*)]$ ]]; then
 		base_path="${BASH_REMATCH[1]}"
-		opts=()
+		opts="$(declare -p def_opts | sed '1s/[^=]*=//')"
 	elif [[ "${f1}" == '$'* ]]; then
-		opts["${f1:1}"]="${f2}"
+		opt="${f1:1}"
+		[[ "${f2}" == '-' ]] && opts["${opt}"]= ||
+			opts["${opt}"]="${f2:-"${def_opts["${opt}"]}"}"
 	else
 		backup "${base_path}/${f1}" "${f2}" \
 			"${opts['retain']}" "${opts['replace']}"