EM_Task/CoreUObject/Private/UObject/EditPropertyChain.cpp

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

#include "CoreMinimal.h"
#include "Templates/Casts.h"
#include "Containers/List.h"
#include "UObject/UnrealType.h"

/* ==========================================================================================================
        FEditPropertyChain
========================================================================================================== */
/**
 * Sets the ActivePropertyNode to the node associated with the property specified.
 *
 * @param	NewActiveProperty	the FProperty that is currently being evaluated by Pre/PostEditChange
 *
 * @return	true if the ActivePropertyNode was successfully changed to the node associated with the property
 *			specified.  false if there was no node corresponding to that property.
 */
bool FEditPropertyChain::SetActivePropertyNode(FProperty* NewActiveProperty)
{
    bool bResult                        = false;

    TDoubleLinkedListNode* PropertyNode = FindNode(NewActiveProperty);
    if (PropertyNode != NULL)
    {
        ActivePropertyNode = PropertyNode;
        bResult            = true;
    }

    return bResult;
}

/**
 * Sets the ActiveMemberPropertyNode to the node associated with the property specified.
 *
 * @param	NewActiveMemberProperty		the member FProperty which contains the property currently being evaluated
 *										by Pre/PostEditChange
 *
 * @return	true if the ActiveMemberPropertyNode was successfully changed to the node associated with the
 *			property specified.  false if there was no node corresponding to that property.
 */
bool FEditPropertyChain::SetActiveMemberPropertyNode(FProperty* NewActiveMemberProperty)
{
    bool bResult                        = false;

    TDoubleLinkedListNode* PropertyNode = FindNode(NewActiveMemberProperty);
    if (PropertyNode != NULL)
    {
        ActiveMemberPropertyNode = PropertyNode;
        bResult                  = true;
    }

    return bResult;
}

bool FEditPropertyChain::IsArchetypeInstanceAffected(UObject* InInstance) const
{
    return !bFilterAffectedInstances || AffectedInstances.Contains(InInstance);
}

/**
 * Returns the node corresponding to the currently active property.
 */
FEditPropertyChain::TDoubleLinkedListNode* FEditPropertyChain::GetActiveNode() const
{
    return ActivePropertyNode;
}

/**
 * Returns the node corresponding to the currently active property, or if the currently active property
 * is not a member variable (i.e. inside of a struct/array), the node corresponding to the member variable
 * which contains the currently active property.
 */
FEditPropertyChain::TDoubleLinkedListNode* FEditPropertyChain::GetActiveMemberNode() const
{
    return ActiveMemberPropertyNode;
}

/**
 * Updates the size reported by Num().  Child classes can use this function to conveniently
 * hook into list additions/removals.
 *
 * This version ensures that the ActivePropertyNode either points to a valid node, or NULL if this list is empty.
 *
 * @param	NewListSize		the new size for this list
 */
void FEditPropertyChain::SetListSize(int32 NewListSize)
{
    int32 PreviousListSize = Num();
    TDoubleLinkedList<FProperty*>::SetListSize(NewListSize);

    if (Num() == 0)
    {
        ActivePropertyNode = ActiveMemberPropertyNode = NULL;
    }
    else if (PreviousListSize != NewListSize)
    {
        // if we have no active property node, set it to the tail of the list, which would be the property that was
        // actually changed by the user (assuming this FEditPropertyChain is being used by the code that handles changes
        // to property values in the editor)
        if (ActivePropertyNode == NULL)
        {
            ActivePropertyNode = GetTail();
        }

        // now figure out which property the ActiveMemberPropertyNode should be pointing at
        if (ActivePropertyNode != NULL)
        {
            // start at the currently active property
            TDoubleLinkedListNode* PropertyNode = ActivePropertyNode;

            // then iterate backwards through the chain, searching for the first property which is owned by a UClass - this is our member property
            for (TIterator It(PropertyNode); It; --It)
            {
                // if we've found the member property, we can stop here
                if (It->GetOwner<UClass>() != nullptr)
                {
                    PropertyNode = It.GetNode();
                    break;
                }
            }

            ActiveMemberPropertyNode = PropertyNode;
        }
    }
}