107 lines
3.3 KiB
C++
107 lines
3.3 KiB
C++
#pragma once
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#include <future>
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#include <utility>
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namespace mbgl {
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// A movable type-erasing function wrapper. This allows to store arbitrary invokable
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// things (like std::function<>, or the result of a movable-only std::bind()) in the queue.
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// Source: http://stackoverflow.com/a/29642072/331379
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class Message {
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public:
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virtual ~Message() = default;
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virtual void operator()() = 0;
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};
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template <class Object, class MemberFn, class ArgsTuple>
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class MessageImpl : public Message {
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public:
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MessageImpl(Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_)
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: object(object_),
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memberFn(memberFn_),
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argsTuple(std::move(argsTuple_)) {
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}
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void operator()() override {
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invoke(std::make_index_sequence<std::tuple_size_v<ArgsTuple>>());
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}
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template <std::size_t... I>
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void invoke(std::index_sequence<I...>) {
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(object.*memberFn)(std::move(std::get<I>(argsTuple))...);
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}
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Object& object;
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MemberFn memberFn;
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ArgsTuple argsTuple;
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};
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template <class ResultType, class Object, class MemberFn, class ArgsTuple>
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class AskMessageImpl : public Message {
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public:
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AskMessageImpl(std::promise<ResultType> promise_, Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_)
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: object(object_),
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memberFn(memberFn_),
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argsTuple(std::move(argsTuple_)),
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promise(std::move(promise_)) {
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}
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void operator()() override {
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promise.set_value(ask(std::make_index_sequence<std::tuple_size_v<ArgsTuple>>()));
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}
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template <std::size_t... I>
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ResultType ask(std::index_sequence<I...>) {
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return (object.*memberFn)(std::move(std::get<I>(argsTuple))...);
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}
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Object& object;
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MemberFn memberFn;
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ArgsTuple argsTuple;
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std::promise<ResultType> promise;
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};
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template <class Object, class MemberFn, class ArgsTuple>
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class AskMessageImpl<void, Object, MemberFn, ArgsTuple> : public Message {
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public:
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AskMessageImpl(std::promise<void> promise_, Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_)
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: object(object_),
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memberFn(memberFn_),
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argsTuple(std::move(argsTuple_)),
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promise(std::move(promise_)) {
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}
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void operator()() override {
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ask(std::make_index_sequence<std::tuple_size_v<ArgsTuple>>());
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promise.set_value();
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}
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template <std::size_t... I>
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void ask(std::index_sequence<I...>) {
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(object.*memberFn)(std::move(std::get<I>(argsTuple))...);
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}
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Object& object;
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MemberFn memberFn;
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ArgsTuple argsTuple;
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std::promise<void> promise;
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};
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namespace actor {
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template <class Object, class MemberFn, class... Args>
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std::unique_ptr<Message> makeMessage(Object& object, MemberFn memberFn, Args&&... args) {
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auto tuple = std::make_tuple(std::forward<Args>(args)...);
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return std::make_unique<MessageImpl<Object, MemberFn, decltype(tuple)>>(object, memberFn, std::move(tuple));
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}
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template <class ResultType, class Object, class MemberFn, class... Args>
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std::unique_ptr<Message> makeMessage(std::promise<ResultType>&& promise, Object& object, MemberFn memberFn, Args&&... args) {
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auto tuple = std::make_tuple(std::forward<Args>(args)...);
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return std::make_unique<AskMessageImpl<ResultType, Object, MemberFn, decltype(tuple)>>(std::move(promise), object, memberFn, std::move(tuple));
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}
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} // namespace actor
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} // namespace mbgl
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