ExternalObjectAndActorDependencyGatherer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#if WITH_EDITOR
 
#include "AssetRegistry/AssetDependencyGatherer.h"
#include "AssetRegistry/AssetData.h"
#include "Containers/Array.h"
#include "Containers/UnrealString.h"
#include "Engine/World.h"
 
struct FARFilter;
struct FARCompiledFilter;
 
//
// This interface is used by systems who inject ContentBundle/ExternalDataLayers in worlds to inform
// FExternalObjectAndActorDependencyGatherer of where to locate those external actors and external objects
// and which CB/EDLs are associated with which world. 
//
// This is necessary since worlds do not store information linking back to which EDL/CB are injected 
// in them.
//
class IExternalAssetPathsProvider
{
    public:
 
        // These functions will be invoked while the AssetRegistry lock is held. All the restrictions 
        // and warnings pertaining to IAssetDependencyGathers apply here. 
        // 
        // Replicated here for clarity....
        // 
        // WARNING: For high performance these callbacks are called inside the critical section of the AssetRegistry. 
        // Attempting to call public functions on the AssetRegistry will deadlock. 
        // To send queries about what assets exist, used the passed-in interface functions instead.
        // 
        // Aside from that these should be made as simple as possible to execute quickly and without side-effects outside
        // of the cache (if using a cache).
        //
 
        struct FUpdateCacheContext
        {
            const FAssetRegistryState& AssetRegistryState;
            const class FPathTree& CachedPathTree;
            const TFunctionRef<FARCompiledFilter(const FARFilter&)> CompileFilterFunc;
        };
 
        virtual void UpdateCache(const FUpdateCacheContext& Context) = 0;
        virtual TArray<FName> GetPathsForPackage(FName PackagePath) = 0;
};
 
class FExternalObjectAndActorDependencyGatherer : public IAssetDependencyGatherer
{
    static IExternalAssetPathsProvider* ExternalPathsProvider;
 
public: 
    FExternalObjectAndActorDependencyGatherer() = default;
    virtual ~FExternalObjectAndActorDependencyGatherer() = default;
    
    static ENGINE_API void SetExternalAssetPathsProvider(IExternalAssetPathsProvider* InProvider);
 
    static ENGINE_API FARFilter GetQueryFilter(FName PackageName, TArray<FString>* OutQueryDirectories = nullptr);
 
    ENGINE_API virtual void GatherDependencies(FGatherDependenciesContext& Context) const override;
};
 
#endif