sh/jshn.sh: add json_for_each_item()

Function usefull to iterate through the different elements of an
array or object; the provided callback function is called for each
element which is passed the value, key and user provided arguments.
For field types different from array or object the callback is called
with the retrieved value.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
Acked-by: Jo-Philipp Wich <jo@mein.io>

sh/jshn.sh

@@ -288,3 +288,28 @@ json_is_a() {
 	json_get_type type "$1"
 	[ "$type" = "$2" ]
 }
+
+json_for_each_item() {
+	[ "$#" -ge 2 ] || return 0
+	local function="$1"; shift
+	local target="$1"; shift
+	local type val
+
+	json_get_type type "$target"
+	case "$type" in
+		object|array)
+			local keys key
+			json_select "$target"
+			json_get_keys keys
+			for key in $keys; do
+				json_get_var val "$key"
+				eval "$function \"\$val\" \"\$key\" \"\$@\""
+			done
+			json_select ..
+		;;
+		*)
+			json_get_var val "$target"
+			eval "$function \"\$val\" \"\" \"\$@\""
+		;;
+	esac
+}