[core] Actor/ActorRef - ask calls to void methods

- allows to wait for execution of void methods as well as non-void methods

1 files changed, 26 insertions, 0 deletions

diff --git a/include/mbgl/actor/message.hpp b/include/mbgl/actor/message.hpp
index 406de425d4..0a20993352 100644
--- a/include/mbgl/actor/message.hpp
+++ b/include/mbgl/actor/message.hpp
@@ -64,6 +64,32 @@ public:
     std::promise<ResultType> promise;
 };
 
+template <class Object, class MemberFn, class ArgsTuple>
+class AskMessageImpl<void, Object, MemberFn, ArgsTuple> : public Message {
+public:
+    AskMessageImpl(std::promise<void> promise_, Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_)
+            : object(object_),
+            memberFn(memberFn_),
+            argsTuple(std::move(argsTuple_)),
+            promise(std::move(promise_)) {
+    }
+
+    void operator()() override {
+        ask(std::make_index_sequence<std::tuple_size<ArgsTuple>::value>());
+        promise.set_value();
+    }
+
+    template <std::size_t... I>
+    void ask(std::index_sequence<I...>) {
+        (object.*memberFn)(std::move(std::get<I>(argsTuple))...);
+    }
+
+    Object& object;
+    MemberFn memberFn;
+    ArgsTuple argsTuple;
+    std::promise<void> promise;
+};
+
 namespace actor {
 
 template <class Object, class MemberFn, class... Args>