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UnrealEngine/Engine/Plugins/Runtime/StateTree/Source/StateTreeModule/Public/StateTreeLinker.h
2025-05-18 13:04:45 +08:00

102 lines
3.4 KiB
C++

// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
#include "StateTreeSchema.h"
#include "StateTreeExecutionTypes.h"
#include "Templates/Casts.h"
#include "StateTreeLinker.generated.h"
UENUM()
enum class EStateTreeLinkerStatus : uint8
{
Succeeded,
Failed,
};
/**
* The StateTree linker is used to resolved references to various StateTree data at load time.
* @see TStateTreeExternalDataHandle<> for example usage.
*/
struct FStateTreeLinker
{
explicit FStateTreeLinker(const UStateTreeSchema* InSchema) : Schema(InSchema) {}
/** @returns the linking status. */
EStateTreeLinkerStatus GetStatus() const { return Status; }
/**
* Links reference to an external UObject.
* @param Handle Reference to TStateTreeExternalDataHandle<> with UOBJECT type to link to.
*/
template <typename T>
typename TEnableIf<TIsDerivedFrom<typename T::DataType, UObject>::IsDerived, void>::Type LinkExternalData(T& Handle)
{
LinkExternalData(Handle, T::DataType::StaticClass(), T::DataRequirement);
}
/**
* Links reference to an external UStruct.
* @param Handle Reference to TStateTreeExternalDataHandle<> with USTRUCT type to link to.
*/
template <typename T>
typename TEnableIf<!TIsDerivedFrom<typename T::DataType, UObject>::IsDerived && !TIsIInterface<typename T::DataType>::Value, void>::Type LinkExternalData(T& Handle)
{
LinkExternalData(Handle, T::DataType::StaticStruct(), T::DataRequirement);
}
/**
* Links reference to an external IInterface.
* @param Handle Reference to TStateTreeExternalDataHandle<> with IINTERFACE type to link to.
*/
template <typename T>
typename TEnableIf<TIsIInterface<typename T::DataType>::Value, void>::Type LinkExternalData(T& Handle)
{
LinkExternalData(Handle, T::DataType::UClassType::StaticClass(), T::DataRequirement);
}
/**
* Links reference to an external Object or Struct.
* This function should only be used when TStateTreeExternalDataHandle<> cannot be used, i.e. the Struct is based on some data.
* @param Handle Reference to link to.
* @param Struct Expected type of the Object or Struct to link to.
* @param Requirement Describes if the external data is expected to be required or optional.
*/
void LinkExternalData(FStateTreeExternalDataHandle& Handle, const UStruct* Struct, const EStateTreeExternalDataRequirement Requirement)
{
if (Schema != nullptr && !Schema->IsExternalItemAllowed(*Struct))
{
UE_LOG(LogStateTree, Error,
TEXT("External data of type '%s' used by current node is not allowed by schema '%s' (i.e. rejected by IsExternalItemAllowed)"),
*Struct->GetName(),
*Schema->GetClass()->GetName());
Handle = FStateTreeExternalDataHandle();
Status = EStateTreeLinkerStatus::Failed;
return;
}
const FStateTreeExternalDataDesc Desc(Struct, Requirement);
int32 Index = ExternalDataDescs.Find(Desc);
if (Index == INDEX_NONE)
{
Index = ExternalDataDescs.Add(Desc);
ExternalDataDescs[Index].Handle.DataHandle = FStateTreeDataHandle(EStateTreeDataSourceType::ExternalData, Index);
}
Handle.DataHandle = ExternalDataDescs[Index].Handle.DataHandle;
}
/** @return linked external data descriptors. */
const TArrayView<const FStateTreeExternalDataDesc> GetExternalDataDescs() const
{
return ExternalDataDescs;
}
protected:
TStrongObjectPtr<const UStateTreeSchema> Schema;
EStateTreeLinkerStatus Status = EStateTreeLinkerStatus::Succeeded;
TArray<FStateTreeExternalDataDesc> ExternalDataDescs;
};