Method SetCapacity

Source/Engine/Core/Collections/HashSetBase.h:148–190

Changes the capacity of the collection. The new capacity. True if preserve collection data when changing its size, otherwise collection after resize will be empty.

    /// <param name="capacity">The new capacity.</param>
    /// <param name="preserveContents">True if preserve collection data when changing its size, otherwise collection after resize will be empty.</param>
    void SetCapacity(int32 capacity, const bool preserveContents = true)
    {
        if (capacity == _size)
            return;
        ASSERT(capacity >= 0);
        AllocationData oldAllocation;
        AllocationUtils::MoveToEmpty<BucketType, AllocationType>(oldAllocation, _allocation, _size, _size);
        const int32 oldSize = _size;
        const int32 oldElementsCount = _elementsCount;
        _deletedCount = _elementsCount = 0;
        if (capacity != 0 && (capacity & (capacity - 1)) != 0)
            capacity = AllocationUtils::AlignToPowerOf2(capacity);
        if (capacity)
        {
            _allocation.Allocate(capacity);
            BucketType* data = _allocation.Get();
            for (int32 i = 0; i < capacity; i++)
                data[i]._state = HashSetBucketState::Empty;
        }
        _size = capacity;
        BucketType* oldData = oldAllocation.Get();
        if (oldElementsCount != 0 && capacity != 0 && preserveContents)
        {
            FindPositionResult pos;
            for (int32 i = 0; i < oldSize; i++)
            {
                BucketType& oldBucket = oldData[i];
                if (oldBucket.IsOccupied())
                {
                    FindPosition(oldBucket.GetKey(), pos);
                    ASSERT(pos.FreeSlotIndex != -1);
                    BucketType& bucket = _allocation.Get()[pos.FreeSlotIndex];
                    bucket = MoveTemp(oldBucket);
                    _elementsCount++;
                }
            }
        }
        if (oldElementsCount != 0)
        {
            for (int32 i = 0; i < oldSize; i++)
                oldData[i].Free();
        }
    }

    /// <summary>
    /// Ensures that collection has given capacity.