LatentActions.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/WeakObjectPtr.h"
 
// The response to updating a latent action
struct FLatentResponse
{
private:
    struct FExecutionInfo
    {
    public:
        FName   ExecutionFunction;
        int32       LinkID;
        FWeakObjectPtr CallbackTarget;
 
        FExecutionInfo(FName InExecutionFunction, int32 InLinkID, FWeakObjectPtr InCallbackTarget)
            : ExecutionFunction(InExecutionFunction)
            , LinkID(InLinkID)
            , CallbackTarget(InCallbackTarget)
        {
        }
 
    private:
        FExecutionInfo()
        {
        }
 
    };
 
protected:
    TArray< FExecutionInfo, TInlineAllocator<4> > LinksToExecute;
    bool bRemoveAction;
    float DeltaTime;
 
    friend struct FLatentActionManager;
public:
    FLatentResponse(float InDeltaTime)
        : bRemoveAction(false)
        , DeltaTime(InDeltaTime)
    {
    }
 
    FLatentResponse& DoneIf(bool Condition)
    {
        bRemoveAction = Condition;
        return *this;
    }
 
    FLatentResponse& TriggerLink(FName ExecutionFunction, int32 LinkID, FWeakObjectPtr InCallbackTarget)
    {
        LinksToExecute.Add(FExecutionInfo(ExecutionFunction, LinkID, InCallbackTarget));
        return *this;
    }
 
    FLatentResponse& FinishAndTriggerIf(bool Condition, FName ExecutionFunction, int32 LinkID, FWeakObjectPtr InCallbackTarget)
    {
        bRemoveAction = Condition;
        if (bRemoveAction)
        {
            LinksToExecute.Add(FExecutionInfo(ExecutionFunction, LinkID, InCallbackTarget));
        }
        return *this;
    }
 
    float ElapsedTime() const { return DeltaTime; }
};
 
// A pending latent action
class FPendingLatentAction
{
public:
    FPendingLatentAction()
    {
    }
 
    virtual ~FPendingLatentAction()
    {
    }
 
    // Return true when the action is completed
    virtual void UpdateOperation(FLatentResponse& Response)
    {
        Response.DoneIf(true);
    }
 
    // Lets the latent action know that the object which originated it has been garbage collected
    // and the action is going to be destroyed (no more UpdateOperation calls will occur and
    // CallbackTarget is already NULL)
    // This is only called when the object goes away before the action is finished; perform normal
    // cleanup when responding that the action is completed in UpdateOperation
    virtual void NotifyObjectDestroyed() {}
 
    virtual void NotifyActionAborted() {}
#if WITH_EDITOR
    // Returns a human readable description of the latent operation's current state
    ENGINE_API virtual FString GetDescription() const;
#endif
};