StateStreamCreator.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Templates/Function.h"
 
#define UE_API STATESTREAM_API
 
class FSceneInterface;
class FStateStreamManagerImpl;
class IStateStream;
 
 
struct FStateStreamRegisterContext
{
    FStateStreamManagerImpl& Manager;
    FSceneInterface* Scene;
 
    UE_API void Register(IStateStream& StateStream, bool TakeOwnership) const;
    UE_API void RegisterDependency(uint32 FromId, uint32 ToId) const;
};
 
 
struct FStateStreamUnregisterContext
{
    FStateStreamManagerImpl& Manager;
};
 
 
class FStateStreamCreator
{
public:
    using FRegisterFunction = TFunction<void(const FStateStreamRegisterContext&)>;
    using FUnregisterFunction = TFunction<void(const FStateStreamUnregisterContext&)>;
 
    UE_API FStateStreamCreator(uint32 Id, FRegisterFunction&& InRegisterFunction, FUnregisterFunction&& InUnregisterFunction);
    UE_API ~FStateStreamCreator();
 
    // Called by system owning StateStreamManager
    UE_API static void RegisterStateStreams(const FStateStreamRegisterContext&);
    UE_API static void UnregisterStateStreams(const FStateStreamUnregisterContext&);
 
private:
    FStateStreamCreator(const FStateStreamCreator&) = delete;
    FStateStreamCreator& operator=(const FStateStreamCreator&) = delete;
 
    FRegisterFunction RegisterFunction;
    FUnregisterFunction UnregisterFunction;
 
    static FStateStreamCreator* First;
    FStateStreamCreator* Next;
    FStateStreamCreator* Prev;
    uint32 Id;
};
 
 
#define STATESTREAM_CREATOR_INSTANCE(ImplName) \
    FStateStreamCreator ImplName##Creator(ImplName::Id, \
        [](const FStateStreamRegisterContext& Context) \
            { ImplName& Impl = *new ImplName(*Context.Scene); Context.Register(Impl, true); }, \
        [](const FStateStreamUnregisterContext& Context) {});
 
#define STATESTREAM_CREATOR_INSTANCE_WITH_DEPENDENCY(ImplName, ToId) \
    FStateStreamCreator ImplName##Creator(ImplName::Id, \
        [](const FStateStreamRegisterContext& Context) \
            { ImplName& Impl = *new ImplName(*Context.Scene); Context.Register(Impl, true); Context.RegisterDependency(ImplName::Id, ToId); }, \
        [](const FStateStreamUnregisterContext& Context) {});
 
#define STATESTREAM_CREATOR_INSTANCE_WITH_FUNC(ImplName, ...) \
    FStateStreamCreator ImplName##Creator(ImplName::Id, \
        [](const FStateStreamRegisterContext& Context) \
            { ImplName& Impl = *new ImplName(*Context.Scene); Context.Register(Impl, true); __VA_ARGS__(Context, Impl); }, \
        [](const FStateStreamUnregisterContext& Context) {});
 
 
#undef UE_API