transfer relations in order

src/RelationDepot.cs

@@ -6,11 +6,13 @@ namespace MoonTools.ECS
 {
 	internal class RelationDepot
 	{
+		private EntityStorage EntityStorage;
 		private TypeIndices RelationTypeIndices;
 		private RelationStorage[] storages = new RelationStorage[256];
 
-		public RelationDepot(TypeIndices relationTypeIndices)
+		public RelationDepot(EntityStorage entityStorage, TypeIndices relationTypeIndices)
 		{
+			EntityStorage = entityStorage;
 			RelationTypeIndices = relationTypeIndices;
 		}
 
@@ -123,26 +125,11 @@ namespace MoonTools.ECS
 			storages[relationTypeIndex].Set(entityA, entityB, relationData);
 		}
 
-		public int GetStorageIndex(int relationTypeIndex, int entityA, int entityB)
-		{
-			return storages[relationTypeIndex].GetStorageIndex(entityA, entityB);
-		}
-
-		public unsafe void* Get(int relationTypeIndex, int relationStorageIndex)
-		{
-			return storages[relationTypeIndex].Get(relationStorageIndex);
-		}
-
 		public void UnrelateAll(int entityID, int relationTypeIndex)
 		{
 			storages[relationTypeIndex].UnrelateAll(entityID);
 		}
 
-		public ReverseSpanEnumerator<Entity> OutRelations(int entityID, int relationTypeIndex)
-		{
-			return storages[relationTypeIndex].OutRelations(entityID);
-		}
-
 		public void Clear()
 		{
 			for (var i = 0; i < storages.Length; i += 1)
@@ -174,5 +161,33 @@ namespace MoonTools.ECS
 				}
 			}
 		}
+
+		public unsafe void TransferStorage(Dictionary<int, int> worldToTransferID, RelationDepot other)
+		{
+			for (var i = 0; i < storages.Length; i += 1)
+			{
+				if (storages[i] != null)
+				{
+					foreach (var (a, b) in storages[i].All())
+					{
+						if (worldToTransferID.TryGetValue(a, out var otherA))
+						{
+							if (worldToTransferID.TryGetValue(b, out var otherB))
+							{
+								var storageIndex = storages[i].GetStorageIndex(a, b);
+								var relationData = storages[i].Get(storageIndex);
+								other.Set(otherA, otherB, i, relationData);
+								other.EntityStorage.AddRelationKind(otherA, i);
+								other.EntityStorage.AddRelationKind(otherB, i);
+							}
+							else
+							{
+								throw new InvalidOperationException($"Missing transfer entity! {EntityStorage.Tag(a.ID)} related to {EntityStorage.Tag(b.ID)}");
+							}
+						}
+					}
+				}
+			}
+		}
 	}
 }

src/RelationStorage.cs

@@ -12,7 +12,7 @@ namespace MoonTools.ECS
 		public abstract int GetStorageIndex(int entityA, int entityB);
 		public abstract unsafe void* Get(int relationStorageIndex);
 		public abstract void UnrelateAll(int entityID);
-		public abstract ReverseSpanEnumerator<Entity> OutRelations(int entityID);
+		public abstract ReverseSpanEnumerator<(Entity, Entity)> All();
 		public abstract RelationStorage CreateStorage();
 		public abstract void Clear();
 	}
@@ -38,7 +38,7 @@ namespace MoonTools.ECS
 			relationDatas = (TRelation*) NativeMemory.Alloc((nuint) (capacity * Unsafe.SizeOf<TRelation>()));
 		}
 
-		public ReverseSpanEnumerator<(Entity, Entity)> All()
+		public override ReverseSpanEnumerator<(Entity, Entity)> All()
 		{
 			return new ReverseSpanEnumerator<(Entity, Entity)>(new Span<(Entity, Entity)>(relations, count));
 		}
@@ -91,7 +91,7 @@ namespace MoonTools.ECS
 			return indices.ContainsKey(relation);
 		}
 
-		public override ReverseSpanEnumerator<Entity> OutRelations(int entityID)
+		public ReverseSpanEnumerator<Entity> OutRelations(int entityID)
 		{
 			if (outRelations.TryGetValue(entityID, out var entityOutRelations))
 			{

src/World.cs

@@ -17,7 +17,7 @@ namespace MoonTools.ECS
 		public World()
 		{
 			ComponentDepot = new ComponentDepot(ComponentTypeIndices);
-			RelationDepot = new RelationDepot(RelationTypeIndices);
+			RelationDepot = new RelationDepot(EntityStorage, RelationTypeIndices);
 			FilterStorage = new FilterStorage(EntityStorage, ComponentTypeIndices);
 		}
 
@@ -79,14 +79,6 @@ namespace MoonTools.ECS
 			EntityStorage.AddRelationKind(entityB.ID, relationTypeIndex);
 		}
 
-		// untyped version for Transfer
-		internal unsafe void Relate(Entity entityA, Entity entityB, int relationTypeIndex, void* relationData)
-		{
-			RelationDepot.Set(entityA, entityB, relationTypeIndex, relationData);
-			EntityStorage.AddRelationKind(entityA.ID, relationTypeIndex);
-			EntityStorage.AddRelationKind(entityB.ID, relationTypeIndex);
-		}
-
 		public void Unrelate<TRelationKind>(in Entity entityA, in Entity entityB) where TRelationKind : unmanaged
 		{
 			var (aEmpty, bEmpty) = RelationDepot.Remove<TRelationKind>(entityA, entityB);
@@ -177,31 +169,8 @@ namespace MoonTools.ECS
 				WorldToTransferID.Add(entity.ID, otherWorldEntity.ID);
 			}
 
-			// FIXME: make sure this preserves relation order, should probably do something similar to filter storage
+			// transfer relations
-			// set relations before components so filters don't freak out
+			RelationDepot.TransferStorage(WorldToTransferID, other.RelationDepot);
-			foreach (var entity in filter.Entities)
-			{
-				var otherWorldEntityA = WorldToTransferID[entity.ID];
-
-				foreach (var relationTypeIndex in EntityStorage.RelationTypeIndices(entity.ID))
-				{
-					foreach (var entityB in RelationDepot.OutRelations(entity.ID, relationTypeIndex))
-					{
-						var storageIndex = RelationDepot.GetStorageIndex(relationTypeIndex, entity.ID, entityB);
-
-						int otherWorldEntityB;
-						if (WorldToTransferID.TryGetValue(entityB, out otherWorldEntityB))
-						{
-							other.Relate(otherWorldEntityA, otherWorldEntityB, relationTypeIndex, RelationDepot.Get(relationTypeIndex, storageIndex));
-						}
-						else
-						{
-							// related entity is not in the filter
-							throw new Exception($"Missing transfer entity! {EntityStorage.Tag(entity.ID)} related to {EntityStorage.Tag(entityB.ID)}");
-						}
-					}
-				}
-			}
 
 			// set components
 			foreach (var entity in filter.Entities)
@@ -214,6 +183,7 @@ namespace MoonTools.ECS
 				}
 			}
 
+			// transfer filters last so callbacks trigger correctly
 			FilterStorage.TransferStorage(WorldToTransferID, other.FilterStorage);
 		}
 	}