ToolCommandChangeSequence.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "InteractiveToolChange.h"
 
 
// This class may be unnecessary, as multiple FChange can be combined in a single transaction.
// Revisit usage in MeshSelectionTool.
 
class FToolCommandChangeSequence : public FToolCommandChange
{
protected:
    struct FChangeElem
    {
        TWeakObjectPtr<UObject> TargetObject;
        TUniquePtr<FToolCommandChange> Change;
    };
 
    TArray<TSharedPtr<FChangeElem>> Sequence;
 
public:
    FToolCommandChangeSequence()
    {
    }
 
    void AppendChange(UObject* Target, TUniquePtr<FToolCommandChange> Change)
    {
        TSharedPtr<FChangeElem> Elem = MakeShared<FChangeElem>();
        Elem->TargetObject = Target;
        Elem->Change = MoveTemp(Change);
        Sequence.Add(Elem);
    }
 
    virtual void Apply(UObject* Object) override
    {
        for (int k = 0; k < Sequence.Num(); ++k)
        {
            TSharedPtr<FChangeElem> Elem = Sequence[k];
            check(Elem->TargetObject.IsValid());
            if (Elem->TargetObject.IsValid())
            {
                Elem->Change->Apply(Elem->TargetObject.Get());
            }
        }
    }
 
    virtual void Revert(UObject* Object) override
    {
        for (int k = Sequence.Num() - 1; k >= 0; --k)
        {
            TSharedPtr<FChangeElem> Elem = Sequence[k];
            check(Elem->TargetObject.IsValid());
            if (Elem->TargetObject.IsValid())
            {
                Elem->Change->Revert(Elem->TargetObject.Get());
            }
        }
    }
 
    virtual FString ToString() const override
    {
        FString Result = TEXT("FCommandChangeSequence: ");
        for (int k = 0; k < Sequence.Num(); ++k)
        {
            Result = Result + Sequence[k]->Change->ToString() + TEXT(" ");
        }
        return Result;
    }
};