// Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "UObject/GCObject.h"

/**
 * Specific implementation of FGCObject that prevents a single UObject-based pointer from being GC'd while this guard is in scope.
 * @note This is the lean version of TStrongObjectPtr which uses an inline FGCObject so *can't* safely be used with containers that treat types as trivially relocatable.
 */
class FGCObjectScopeGuard: public FGCObject
{
public:
    explicit FGCObjectScopeGuard(const UObject* InObject)
        : Object(InObject)
    {
    }

    virtual ~FGCObjectScopeGuard()
    {
    }

    /** Non-copyable */
    FGCObjectScopeGuard(const FGCObjectScopeGuard&)            = delete;
    FGCObjectScopeGuard& operator=(const FGCObjectScopeGuard&) = delete;

    //~ FGCObject interface
    virtual void AddReferencedObjects(FReferenceCollector& Collector) override
    {
        Collector.AddReferencedObject(Object);
    }

    virtual FString GetReferencerName() const override
    {
        return TEXT("FGCObjectScopeGuard");
    }

private:
    const UObject* Object;
};

/**
 * Specific implementation of FGCObject that prevents an array of UObject-based pointers from being GC'd while this guard is in scope.
 */
template <typename ObjectType>
class TGCObjectsScopeGuard: public FGCObject
{
    static_assert(TPointerIsConvertibleFromTo<ObjectType, const UObjectBase>::Value, "TGCObjectsScopeGuard: ObjectType must be pointers to a type derived from UObject");

public:
    explicit TGCObjectsScopeGuard(const TArray<ObjectType*>& InObjects)
        : Objects(InObjects)
    {
    }

    virtual ~TGCObjectsScopeGuard()
    {
    }

    /** Non-copyable */
    TGCObjectsScopeGuard(const TGCObjectsScopeGuard&)            = delete;
    TGCObjectsScopeGuard& operator=(const TGCObjectsScopeGuard&) = delete;

    //~ FGCObject interface
    virtual void AddReferencedObjects(FReferenceCollector& Collector) override
    {
        Collector.AddReferencedObjects(Objects);
    }

    virtual FString GetReferencerName() const override
    {
        return TEXT("TGCObjectsScopeGuard");
    }

private:
    TArray<ObjectType*> Objects;
};