Entity Operation Batching

EntityBatchOperation.cs

    public class EntityBatchOperation
    {
        private const int NoComponentTypeId = -1;
        
        private Entity _entity;
        private List<int> _componentsAdded = new List<int>();
        private List<int> _componentsRemoved = new List<int>();

        public EntityBatchOperation(Entity entity)
        {
            _entity = entity;
        }

        public void AddComponent<T>(T component, int componentTypeId = NoComponentTypeId) where T : IComponent
        {
            if (componentTypeId == NoComponentTypeId)
            {
                var componentType = component.GetType();
                componentTypeId = _entity.ComponentTypeLookup.GetComponentType(componentType);
            }
            
            var allocationId = _entity.ComponentDatabase.Allocate(componentTypeId);
            _entity.InternalComponentAllocations[componentTypeId] = allocationId;
            _entity.ComponentDatabase.Set(componentTypeId, allocationId, component);
            _componentsAdded.Add(componentTypeId);
        }
        
        public void RemoveComponent<T>(T component, int componentTypeId = NoComponentTypeId) where T : IComponent
        {
            if (componentTypeId == NoComponentTypeId)
            {
                var componentType = component.GetType();
                componentTypeId = _entity.ComponentTypeLookup.GetComponentType(componentType);
            }

            if (_entity.InternalComponentAllocations[componentTypeId] == Entity.NotAllocated)
            { return; }
            
            _componentsRemoved.Add(componentTypeId);
        }

        public void Finish()
        {
            var componentsAddedSubject = (Subject<int[]>) _entity.ComponentsAdded;
            var componentsRemovingSubject = (Subject<int[]>) _entity.ComponentsRemoving;
            var componentsRemovedSubject = (Subject<int[]>) _entity.ComponentsRemoved;
            componentsAddedSubject.OnNext(_componentsAdded.ToArray());

            var removalArray = _componentsRemoved.ToArray();
            componentsRemovingSubject.OnNext(removalArray);
            
            for (var i = 0; i < removalArray.Length; i++)
            {
                var componentTypeId = _componentsRemoved[i];
                var allocationIndex = _entity.InternalComponentAllocations[componentTypeId];
                _entity.ComponentDatabase.Remove(componentTypeId, allocationIndex);
                _entity.InternalComponentAllocations[componentTypeId] = Entity.NotAllocated;
            }
            
            componentsRemovedSubject.OnNext(removalArray);
        }
    }