Method Compact

Source/Engine/Core/Collections/HashSetBase.h:400–444

    }

    void Compact()
    {
        if (_elementsCount == 0)
        {
            // Fast path if it's empty
            BucketType* data = _allocation.Get();
            for (int32 i = 0; i < _size; ++i)
                data[i]._state = HashSetBucketState::Empty;
        }
        else
        {
            // Rebuild entire table completely
            const int32 elementsCount = _elementsCount;
            const int32 oldSize = _size;
            AllocationData oldAllocation;
            AllocationUtils::MoveToEmpty<BucketType, AllocationType>(oldAllocation, _allocation, oldSize, oldSize);
            _allocation.Allocate(_size);
            BucketType* data = _allocation.Get();
            for (int32 i = 0; i < oldSize; ++i)
                data[i]._state = HashSetBucketState::Empty;
            BucketType* oldData = oldAllocation.Get();
            FindPositionResult pos;
            for (int32 i = 0; i < oldSize; ++i)
            {
                BucketType& oldBucket = oldData[i];
                if (oldBucket.IsOccupied())
                {
                    FindPosition(oldBucket.GetKey(), pos);
                    if (pos.FreeSlotIndex == -1)
                    {
                        // Grow and retry to handle pathological cases (eg. heavy collisions)
                        EnsureCapacity(_size + 1, true);
                        FindPosition(oldBucket.GetKey(), pos);
                        ASSERT(pos.FreeSlotIndex != -1);
                    }
                    BucketType& bucket = _allocation.Get()[pos.FreeSlotIndex];
                    bucket = MoveTemp(oldBucket);
                }
            }
            for (int32 i = 0; i < oldSize; ++i)
                oldData[i].Free();
            _elementsCount = elementsCount;
        }
        _deletedCount = 0;
    }
};