amencke/scatter_hierarchy_variadic.cpp

## scatter_hierarchy_variadic.cpp
struct NullType
{
};

template <typename... Ts>
struct TypeList;

template <typename Head, typename... Tail>
struct TypeList<Head, Tail...>
{
    using H = Head;
    using T = TypeList<Tail...>;
};

template <typename Head>
struct TypeList<Head>
{
    using H = Head;
    using T = NullType;
};

template<>
struct TypeList<>
{};

template <template <typename M> typename B, class TList>
class ActorBehaviorScatterHierarchy;

template <template <typename M> typename B, class T1, class... Ts>
class ActorBehaviorScatterHierarchy<B, TypeList<T1, Ts...>>
    : public ActorBehaviorScatterHierarchy<B, T1>
    , public ActorBehaviorScatterHierarchy<B, TypeList<Ts...>>
{
public:
    using TList = TypeList<T1, Ts...>;
    using LeftBase = ActorBehaviorScatterHierarchy<B, T1>;
    using RightBase = ActorBehaviorScatterHierarchy<B, TypeList<Ts...>>;
};

template <template <typename> typename B, typename AtomicType>
class ActorBehaviorScatterHierarchy: public B<AtomicType>
{
    using LeftBase = B<AtomicType>;
};

template <template <typename M> typename B>
class ActorBehaviorScatterHierarchy<B, NullType>
{
};

// static_actor_test.cpp

#include "behavior_scatter_hierarchy_variadic.h"

#include <iostream>

struct Message1
{
    uint32_t x = 5;
};

struct Message2
{
    float f = 0.123;
};

struct Message3
{
    std::string s = "hello!";
};

struct Message4
{
    const char* s = "something";
};

template <typename Msg>
struct Behavior
{
    Msg message_;
};

int main(void)
{
    using MyActorBehaviorHierarchy = ActorBehaviorScatterHierarchy<Behavior, TypeList<Message1, Message2, Message3, Message4>>;

    MyActorBehaviorHierarchy a;

    std::cout << static_cast<Behavior<Message1>>(a).message_.x << std::endl;
    std::cout << static_cast<Behavior<Message2>>(a).message_.f << std::endl;
    std::cout << static_cast<Behavior<Message3>>(a).message_.s << std::endl;
    std::cout << static_cast<Behavior<Message4>>(a).message_.s << std::endl;

    // ➜  static_actor ./build/static_actor
    // 5
    // 0.123
    // hello!
    // something
};
	struct NullType
	{
	};

	template <typename... Ts>
	struct TypeList;

	template <typename Head, typename... Tail>
	struct TypeList<Head, Tail...>
	{
	using H = Head;
	using T = TypeList<Tail...>;
	};

	template <typename Head>
	struct TypeList<Head>
	{
	using H = Head;
	using T = NullType;
	};

	template<>
	struct TypeList<>
	{};

	template <template <typename M> typename B, class TList>
	class ActorBehaviorScatterHierarchy;

	template <template <typename M> typename B, class T1, class... Ts>
	class ActorBehaviorScatterHierarchy<B, TypeList<T1, Ts...>>
	: public ActorBehaviorScatterHierarchy<B, T1>
	, public ActorBehaviorScatterHierarchy<B, TypeList<Ts...>>
	{
	public:
	using TList = TypeList<T1, Ts...>;
	using LeftBase = ActorBehaviorScatterHierarchy<B, T1>;
	using RightBase = ActorBehaviorScatterHierarchy<B, TypeList<Ts...>>;
	};

	template <template <typename> typename B, typename AtomicType>
	class ActorBehaviorScatterHierarchy: public B<AtomicType>
	{
	using LeftBase = B<AtomicType>;
	};

	template <template <typename M> typename B>
	class ActorBehaviorScatterHierarchy<B, NullType>
	{
	};

	// static_actor_test.cpp

	#include "behavior_scatter_hierarchy_variadic.h"

	#include <iostream>

	struct Message1
	{
	uint32_t x = 5;
	};

	struct Message2
	{
	float f = 0.123;
	};

	struct Message3
	{
	std::string s = "hello!";
	};

	struct Message4
	{
	const char* s = "something";
	};

	template <typename Msg>
	struct Behavior
	{
	Msg message_;
	};

	int main(void)
	{
	using MyActorBehaviorHierarchy = ActorBehaviorScatterHierarchy<Behavior, TypeList<Message1, Message2, Message3, Message4>>;

	MyActorBehaviorHierarchy a;

	std::cout << static_cast<Behavior<Message1>>(a).message_.x << std::endl;
	std::cout << static_cast<Behavior<Message2>>(a).message_.f << std::endl;
	std::cout << static_cast<Behavior<Message3>>(a).message_.s << std::endl;
	std::cout << static_cast<Behavior<Message4>>(a).message_.s << std::endl;

	// ➜ static_actor ./build/static_actor
	// 5
	// 0.123
	// hello!
	// something
	};