lib/dbus/ReadIter: add ForEachProperty()

src/lib/dbus/ReadIter.hxx

@@ -102,6 +102,28 @@ public:
 				f(i.Recurse());
 			});
 	}
+
+	/**
+	 * Invoke a function for each name/value pair (string/variant)
+	 * in a dictionary (array containing #DBUS_TYPE_DICT_ENTRY).
+	 * The function gets two parameters: the property name (as C
+	 * string) and the variant value (as #ReadMessageIter).
+	 */
+	template<typename F>
+	void ForEachProperty(F &&f) {
+		ForEachRecurse(DBUS_TYPE_DICT_ENTRY, [&f](auto &&i){
+				if (i.GetArgType() != DBUS_TYPE_STRING)
+					return;
+
+				const char *name = i.GetString();
+				i.Next();
+
+				if (i.GetArgType() != DBUS_TYPE_VARIANT)
+					return;
+
+				f(name, i.Recurse());
+			});
+	}
 };
 
 } /* namespace ODBus */