diff options
Diffstat (limited to 'include/mbgl/actor/message.hpp')
-rw-r--r-- | include/mbgl/actor/message.hpp | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/include/mbgl/actor/message.hpp b/include/mbgl/actor/message.hpp new file mode 100644 index 0000000000..0a20993352 --- /dev/null +++ b/include/mbgl/actor/message.hpp @@ -0,0 +1,108 @@ +#pragma once + +#include <mbgl/util/optional.hpp> + +#include <future> +#include <utility> + +namespace mbgl { + +// A movable type-erasing function wrapper. This allows to store arbitrary invokable +// things (like std::function<>, or the result of a movable-only std::bind()) in the queue. +// Source: http://stackoverflow.com/a/29642072/331379 +class Message { +public: + virtual ~Message() = default; + virtual void operator()() = 0; +}; + +template <class Object, class MemberFn, class ArgsTuple> +class MessageImpl : public Message { +public: + MessageImpl(Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_) + : object(object_), + memberFn(memberFn_), + argsTuple(std::move(argsTuple_)) { + } + + void operator()() override { + invoke(std::make_index_sequence<std::tuple_size<ArgsTuple>::value>()); + } + + template <std::size_t... I> + void invoke(std::index_sequence<I...>) { + (object.*memberFn)(std::move(std::get<I>(argsTuple))...); + } + + Object& object; + MemberFn memberFn; + ArgsTuple argsTuple; +}; + +template <class ResultType, class Object, class MemberFn, class ArgsTuple> +class AskMessageImpl : public Message { +public: + AskMessageImpl(std::promise<ResultType> promise_, Object& object_, MemberFn memberFn_, ArgsTuple argsTuple_) + : object(object_), + memberFn(memberFn_), + argsTuple(std::move(argsTuple_)), + promise(std::move(promise_)) { + } + + void operator()() override { + promise.set_value(ask(std::make_index_sequence<std::tuple_size<ArgsTuple>::value>())); + } + + template <std::size_t... I> + ResultType ask(std::index_sequence<I...>) { + return (object.*memberFn)(std::move(std::get<I>(argsTuple))...); + } + + Object& object; + MemberFn memberFn; + ArgsTuple argsTuple; + 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> +std::unique_ptr<Message> makeMessage(Object& object, MemberFn memberFn, Args&&... args) { + auto tuple = std::make_tuple(std::forward<Args>(args)...); + return std::make_unique<MessageImpl<Object, MemberFn, decltype(tuple)>>(object, memberFn, std::move(tuple)); +} + +template <class ResultType, class Object, class MemberFn, class... Args> +std::unique_ptr<Message> makeMessage(std::promise<ResultType>&& promise, Object& object, MemberFn memberFn, Args&&... args) { + auto tuple = std::make_tuple(std::forward<Args>(args)...); + return std::make_unique<AskMessageImpl<ResultType, Object, MemberFn, decltype(tuple)>>(std::move(promise), object, memberFn, std::move(tuple)); +} + +} // namespace actor +} // namespace mbgl |