initial snapshot system

src/ComponentDepot.cs

@@ -87,5 +87,28 @@ namespace MoonTools.ECS
 		{
 			Lookup<TComponent>().Remove(entityID);
 		}
+
+		public void Clear()
+		{
+			for (var i = 0; i < ComponentTypeIndices.Count; i += 1)
+			{
+				if (storages[i] != null)
+				{
+					storages[i].Clear();
+				}
+			}
+		}
+
+		// used to fill snapshot depot with correct storages
+		public void FillMissingStorages(ComponentDepot other)
+		{
+			for (var i = 0; i < ComponentTypeIndices.Count; i += 1)
+			{
+				if (storages[i] == null && other.storages[i] != null)
+				{
+					storages[i] = other.storages[i].CreateStorage();
+				}
+			}
+		}
 	}
 }

src/ComponentStorage.cs

@@ -8,12 +8,12 @@ namespace MoonTools.ECS
 	{
 		internal abstract void Set(int entityID, object component);
 		public abstract bool Remove(int entityID);
-		public abstract ComponentStorageState CreateState();
+		public abstract void Clear();
-		public abstract void Save(ComponentStorageState state);
-		public abstract void Load(ComponentStorageState state);
 
 		// used for debugging and template instantiation
 		internal abstract object UntypedGet(int entityID);
+		// used to create correctly typed storage on snapshot
+		public abstract ComponentStorage CreateStorage();
 	}
 
 	internal class ComponentStorage<TComponent> : ComponentStorage where TComponent : unmanaged
@@ -101,7 +101,7 @@ namespace MoonTools.ECS
 			return false;
 		}
 
-		public void Clear()
+		public override void Clear()
 		{
 			nextID = 0;
 			entityIDToStorageIndex.Clear();
@@ -123,43 +123,9 @@ namespace MoonTools.ECS
 			return new Entity(entityIDs[0]);
 		}
 
-		public override ComponentStorageState CreateState()
+		public override ComponentStorage<TComponent> CreateStorage()
 		{
-			return ComponentStorageState.Create<TComponent>(nextID);
+			return new ComponentStorage<TComponent>();
-		}
-
-		public override void Save(ComponentStorageState state)
-		{
-			ReadOnlySpan<byte> entityIDBytes = MemoryMarshal.Cast<int, byte>(new ReadOnlySpan<int>(entityIDs, 0, nextID));
-
-			if (entityIDBytes.Length > state.EntityIDs.Length)
-			{
-				Array.Resize(ref state.EntityIDs, entityIDBytes.Length);
-			}
-			entityIDBytes.CopyTo(state.EntityIDs);
-
-			ReadOnlySpan<byte> componentBytes = MemoryMarshal.Cast<TComponent, byte>(AllComponents());
-			if (componentBytes.Length > state.Components.Length)
-			{
-				Array.Resize(ref state.Components, componentBytes.Length);
-			}
-			componentBytes.CopyTo(state.Components);
-
-			state.Count = nextID;
-		}
-
-		public override void Load(ComponentStorageState state)
-		{
-			state.EntityIDs.CopyTo(MemoryMarshal.Cast<int, byte>(entityIDs));
-			state.Components.CopyTo(MemoryMarshal.Cast<TComponent, byte>(components));
-
-			entityIDToStorageIndex.Clear();
-			for (var i = 0; i < state.Count; i += 1)
-			{
-				entityIDToStorageIndex[entityIDs[i]] = i;
-			}
-
-			nextID = state.Count;
 		}
 	}
 }

src/EntityComponentReader.cs

@@ -52,11 +52,6 @@ namespace MoonTools.ECS
 			return ComponentDepot.GetSingletonEntity<TComponent>();
 		}
 
-		protected bool Exists(in Entity entity)
-		{
-			return EntityStorage.Exists(entity);
-		}
-
 		protected IEnumerable<(Entity, Entity, TRelationKind)> Relations<TRelationKind>() where TRelationKind : unmanaged
 		{
 			return RelationDepot.Relations<TRelationKind>();

src/EntityStorage.cs

@@ -7,11 +7,14 @@ namespace MoonTools.ECS
 		private int nextID = 0;
 		// FIXME: why is this duplicated?
 		private readonly Stack<int> availableIDs = new Stack<int>();
+		// FIXME: this is only needed in debug mode
 		private readonly HashSet<int> availableIDHash = new HashSet<int>();
 
 		private Dictionary<int, HashSet<int>> EntityToComponentTypeIndices = new Dictionary<int, HashSet<int>>();
 		private Dictionary<int, HashSet<int>> EntityToRelationTypeIndices = new Dictionary<int, HashSet<int>>();
 
+		public int Count => nextID - availableIDs.Count;
+
 		public Entity Create()
 		{
 			var entity = new Entity(NextID());
@@ -70,6 +73,21 @@ namespace MoonTools.ECS
 			return EntityToRelationTypeIndices[entityID];
 		}
 
+		public void Clear()
+		{
+			nextID = 0;
+			foreach (var componentSet in EntityToComponentTypeIndices.Values)
+			{
+				componentSet.Clear();
+			}
+			foreach (var relationSet in EntityToRelationTypeIndices.Values)
+			{
+				relationSet.Clear();
+			}
+			availableIDs.Clear();
+			availableIDHash.Clear();
+		}
+
 		private int NextID()
 		{
 			if (availableIDs.Count > 0)

src/IndexableSet.cs

@@ -84,32 +84,5 @@ namespace MoonTools.ECS
 		{
 			Count = 0;
 		}
-
-		public void Save(IndexableSetState<T> state)
-		{
-			ReadOnlySpan<byte> arrayBytes = MemoryMarshal.Cast<T, byte>(array);
-
-			if (arrayBytes.Length > state.Array.Length)
-			{
-				Array.Resize(ref state.Array, arrayBytes.Length);
-			}
-
-			arrayBytes.CopyTo(state.Array);
-
-			state.Count = Count;
-		}
-
-		public void Load(IndexableSetState<T> state)
-		{
-			state.Array.CopyTo(MemoryMarshal.Cast<T, byte>(array));
-
-			indices.Clear();
-			for (var i = 0; i < state.Count; i += 1)
-			{
-				indices[array[i]] = i;
-			}
-
-			Count = state.Count;
-		}
 	}
 }

src/RelationStorage.cs

@@ -6,9 +6,6 @@ namespace MoonTools.ECS
 {
 	internal abstract class RelationStorage
 	{
-		public abstract RelationStorageState CreateState();
-		public abstract void Save(RelationStorageState state);
-		public abstract void Load(RelationStorageState state);
 		public abstract void UnrelateAll(int entityID);
 	}
 
@@ -228,60 +225,5 @@ namespace MoonTools.ECS
 			hashSet.Clear();
 			listPool.Push(hashSet);
 		}
-
-		public override RelationStorageState CreateState()
-		{
-			return RelationStorageState.Create<TRelation>(count);
-		}
-
-		public override void Save(RelationStorageState state)
-		{
-			ReadOnlySpan<byte> relationBytes = MemoryMarshal.Cast<Relation, byte>(relations);
-
-			if (relationBytes.Length > state.Relations.Length)
-			{
-				Array.Resize(ref state.Relations, relationBytes.Length);
-			}
-			relationBytes.CopyTo(state.Relations);
-
-			ReadOnlySpan<byte> relationDataBytes = MemoryMarshal.Cast<TRelation, byte>(relationDatas);
-
-			if (relationDataBytes.Length > state.RelationDatas.Length)
-			{
-				Array.Resize(ref state.RelationDatas, relationDataBytes.Length);
-			}
-			relationDataBytes.CopyTo(state.RelationDatas);
-
-			state.Count = count;
-		}
-
-		public override void Load(RelationStorageState state)
-		{
-			state.Relations.CopyTo(MemoryMarshal.Cast<Relation, byte>(relations));
-			state.RelationDatas.CopyTo(MemoryMarshal.Cast<TRelation, byte>(relationDatas));
-
-			indices.Clear();
-			outRelations.Clear();
-			inRelations.Clear();
-			for (var i = 0; i < state.Count; i += 1)
-			{
-				var relation = relations[i];
-				indices[relation] = i;
-
-				if (!outRelations.ContainsKey(relation.A.ID))
-				{
-					outRelations[relation.A.ID] = AcquireHashSetFromPool();
-				}
-				outRelations[relation.A.ID].Add(relation.B.ID);
-
-				if (!inRelations.ContainsKey(relation.B.ID))
-				{
-					inRelations[relation.B.ID] = AcquireHashSetFromPool();
-				}
-				inRelations[relation.B.ID].Add(relation.A.ID);
-			}
-
-			count = state.Count;
-		}
 	}
 }

src/Snapshot.cs

@@ -0,0 +1,66 @@
+namespace MoonTools.ECS
+{
+	public class Snapshot
+	{
+		private World World;
+		private Filter? Filter;
+
+		private EntityStorage SnapshotEntityStorage;
+		private ComponentDepot SnapshotComponentDepot;
+
+		internal Snapshot(World world)
+		{
+			World = world;
+			SnapshotEntityStorage = new EntityStorage();
+			SnapshotComponentDepot = new ComponentDepot(World.ComponentTypeIndices);
+		}
+
+		public void Take(Filter filter)
+		{
+			Clear();
+			Filter = filter;
+			SnapshotComponentDepot.FillMissingStorages(World.ComponentDepot);
+
+			foreach (var worldEntity in filter.Entities)
+			{
+				var snapshotEntity = SnapshotEntityStorage.Create();
+				foreach (var componentTypeIndex in World.EntityStorage.ComponentTypeIndices(worldEntity.ID))
+				{
+					SnapshotEntityStorage.SetComponent(snapshotEntity.ID, componentTypeIndex);
+					SnapshotComponentDepot.Set(snapshotEntity.ID, componentTypeIndex, World.ComponentDepot.UntypedGet(worldEntity.ID, componentTypeIndex));
+				}
+			}
+		}
+
+		public void Restore()
+		{
+			if (Filter == null)
+			{
+				return;
+			}
+
+			foreach (var entity in Filter.Entities)
+			{
+				World.Destroy(entity);
+			}
+
+			for (var i = 0; i < SnapshotEntityStorage.Count; i += 1)
+			{
+				var entity = World.CreateEntity();
+
+				foreach (var componentTypeIndex in SnapshotEntityStorage.ComponentTypeIndices(i))
+				{
+					World.EntityStorage.SetComponent(entity.ID, componentTypeIndex);
+					World.FilterStorage.Check(entity.ID, componentTypeIndex);
+					World.ComponentDepot.Set(entity.ID, componentTypeIndex, SnapshotComponentDepot.UntypedGet(i, componentTypeIndex));
+				}
+			}
+		}
+
+		private void Clear()
+		{
+			SnapshotEntityStorage.Clear();
+			SnapshotComponentDepot.Clear();
+		}
+	}
+}

src/State/ComponentDepotState.cs

@@ -1,11 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-	internal class ComponentDepotState
-	{
-		public Dictionary<Type, ComponentStorageState> StorageStates = new Dictionary<Type, ComponentStorageState>();
-		public Dictionary<FilterSignature, IndexableSetState<int>> FilterStates = new Dictionary<FilterSignature, IndexableSetState<int>>();
-	}
-}

src/State/ComponentStorageState.cs

@@ -1,27 +0,0 @@
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-    internal class ComponentStorageState
-    {
-		public int Count;
-		public byte[] EntityIDs;
-		public byte[] Components;
-
-        public unsafe static ComponentStorageState Create<TComponent>(int count) where TComponent : unmanaged
-        {
-			return new ComponentStorageState(
-                count,
-                count * sizeof(int),
-                count * sizeof(TComponent)
-            );
-		}
-
-        private ComponentStorageState(int count, int entityIDSize, int componentSize)
-        {
-			Count = count;
-			EntityIDs = new byte[entityIDSize];
-			Components = new byte[componentSize];
-		}
-	}
-}

src/State/EntityStorageState.cs

@@ -1,13 +0,0 @@
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-    internal class EntityStorageState
-    {
-		public int NextID;
-		public List<int> availableIDs = new List<int>();
-
-		public Dictionary<int, HashSet<int>> EntityToComponentTypeIndices = new Dictionary<int, HashSet<int>>();
-		public Dictionary<int, HashSet<int>> EntityToRelationTypeIndices = new Dictionary<int, HashSet<int>>();
-	}
-}

src/State/IndexableSetState.cs

@@ -1,16 +0,0 @@
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-    internal class IndexableSetState<T> where T : unmanaged
-    {
-		public int Count;
-		public byte[] Array;
-
-        public unsafe IndexableSetState(int count)
-        {
-			Count = count;
-			Array = new byte[sizeof(T) * count];
-		}
-	}
-}

src/State/RelationDepotState.cs

@@ -1,10 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-    internal class RelationDepotState
-    {
-		public Dictionary<Type, RelationStorageState> StorageStates = new Dictionary<Type, RelationStorageState>();
-	}
-}

src/State/RelationStorageState.cs

@@ -1,27 +0,0 @@
-using System.Collections.Generic;
-
-namespace MoonTools.ECS
-{
-	internal class RelationStorageState
-	{
-		public int Count;
-		public byte[] Relations;
-		public byte[] RelationDatas;
-
-		public unsafe static RelationStorageState Create<TRelation>(int count) where TRelation : unmanaged
-		{
-			return new RelationStorageState(
-				count,
-				count * sizeof(Relation),
-				count * sizeof(TRelation)
-			);
-		}
-
-		private RelationStorageState(int count, int relationSize, int relationDataSize)
-		{
-			Count = count;
-			Relations = new byte[relationSize];
-			RelationDatas = new byte[relationDataSize];
-		}
-	}
-}

src/State/WorldState.cs

@@ -1,16 +0,0 @@
-namespace MoonTools.ECS
-{
-    public class WorldState
-    {
-		internal readonly ComponentDepotState ComponentDepotState;
-		internal readonly EntityStorageState EntityStorageState;
-		internal readonly RelationDepotState RelationDepotState;
-
-		public WorldState()
-        {
-			ComponentDepotState = new ComponentDepotState();
-			EntityStorageState = new EntityStorageState();
-			RelationDepotState = new RelationDepotState();
-		}
-	}
-}

src/System.cs

@@ -11,27 +11,9 @@ namespace MoonTools.ECS
 
 		public abstract void Update(TimeSpan delta);
 
-		protected Entity CreateEntity()
+		protected Entity CreateEntity() => World.CreateEntity();
-		{
-			return EntityStorage.Create();
-		}
 
-		protected void Set<TComponent>(in Entity entity, in TComponent component) where TComponent : unmanaged
+		protected void Set<TComponent>(in Entity entity, in TComponent component) where TComponent : unmanaged => World.Set<TComponent>(entity, component);
-		{
-#if DEBUG
-			// check for use after destroy
-			if (!Exists(entity))
-			{
-				throw new ArgumentException("This entity is not valid!");
-			}
-#endif
-			if (EntityStorage.SetComponent(entity.ID, ComponentTypeIndices.GetIndex<TComponent>()))
-			{
-				FilterStorage.Check<TComponent>(entity.ID);
-			}
-
-			ComponentDepot.Set<TComponent>(entity.ID, component);
-		}
 
 		protected void Remove<TComponent>(in Entity entity) where TComponent : unmanaged
 		{
@@ -42,27 +24,9 @@ namespace MoonTools.ECS
 			}
 		}
 
-		protected void Set<TComponent>(in Template template, in TComponent component) where TComponent : unmanaged
+		protected void Set<TComponent>(in Template template, in TComponent component) where TComponent : unmanaged => World.Set<TComponent>(template, component);
-		{
-			var componentTypeIndex = ComponentTypeIndices.GetIndex<TComponent>();
-			TemplateStorage.SetComponent(template.ID, componentTypeIndex);
-			TemplateComponentDepot.Set(template.ID, component);
-			ComponentDepot.Register<TComponent>(componentTypeIndex);
-		}
 
-		protected Entity Instantiate(in Template template)
+		protected Entity Instantiate(in Template template) => World.Instantiate(template);
-		{
-			var entity = EntityStorage.Create();
-
-			foreach (var componentTypeIndex in TemplateStorage.ComponentTypeIndices(template.ID))
-			{
-				EntityStorage.SetComponent(entity.ID, componentTypeIndex);
-				FilterStorage.Check(entity.ID, componentTypeIndex);
-				ComponentDepot.Set(entity.ID, componentTypeIndex, TemplateComponentDepot.UntypedGet(template.ID, componentTypeIndex));
-			}
-
-			return entity;
-		}
 
 		protected ReadOnlySpan<TMessage> ReadMessages<TMessage>() where TMessage : unmanaged
 		{
@@ -128,20 +92,6 @@ namespace MoonTools.ECS
 			EntityStorage.RemoveRelation(entity.ID, RelationTypeIndices.GetIndex<TRelationKind>());
 		}
 
-		protected void Destroy(in Entity entity)
+		protected void Destroy(in Entity entity) => World.Destroy(entity);
-		{
-			foreach (var componentTypeIndex in EntityStorage.ComponentTypeIndices(entity.ID))
-			{
-				ComponentDepot.Remove(entity.ID, componentTypeIndex);
-				FilterStorage.RemoveEntity(entity.ID, componentTypeIndex);
-			}
-
-			foreach (var relationTypeIndex in EntityStorage.RelationTypeIndices(entity.ID))
-			{
-				RelationDepot.UnrelateAll(entity.ID, relationTypeIndex);
-			}
-
-			EntityStorage.Destroy(entity);
-		}
 	}
 }

src/TypeIndices.cs

@@ -7,6 +7,7 @@ namespace MoonTools.ECS
 	{
 		Dictionary<Type, int> TypeToIndex = new Dictionary<Type, int>();
 		int nextID = 0;
+		public int Count => TypeToIndex.Count;
 
 		public int GetIndex<T>() where T : unmanaged
 		{
@@ -24,6 +25,7 @@ namespace MoonTools.ECS
 			return TypeToIndex[type];
 		}
 
+
 #if DEBUG
 		public IEnumerable<Type> Types => TypeToIndex.Keys;
 #endif

src/World.cs

@@ -1,4 +1,6 @@
-namespace MoonTools.ECS
+using System;
+
+namespace MoonTools.ECS
 {
 	public class World
 	{
@@ -9,11 +11,11 @@
 		internal readonly MessageDepot MessageDepot = new MessageDepot();
 		internal readonly RelationDepot RelationDepot;
 		internal readonly FilterStorage FilterStorage;
+		public FilterBuilder FilterBuilder => new FilterBuilder(FilterStorage, ComponentTypeIndices);
 
 		internal readonly TemplateStorage TemplateStorage = new TemplateStorage();
 		internal readonly ComponentDepot TemplateComponentDepot;
 
-
 		public World()
 		{
 			ComponentDepot = new ComponentDepot(ComponentTypeIndices);
@@ -29,6 +31,13 @@
 
 		public void Set<TComponent>(Entity entity, in TComponent component) where TComponent : unmanaged
 		{
+#if DEBUG
+			// check for use after destroy
+			if (!EntityStorage.Exists(entity))
+			{
+				throw new InvalidOperationException("This entity is not valid!");
+			}
+#endif
 			if (EntityStorage.SetComponent(entity.ID, ComponentTypeIndices.GetIndex<TComponent>()))
 			{
 				FilterStorage.Check<TComponent>(entity.ID);
@@ -44,11 +53,12 @@
 
 		public void Set<TComponent>(in Template template, in TComponent component) where TComponent : unmanaged
 		{
-			TemplateStorage.SetComponent(template.ID, ComponentTypeIndices.GetIndex<TComponent>());
+			var componentTypeIndex = ComponentTypeIndices.GetIndex<TComponent>();
+			TemplateStorage.SetComponent(template.ID, componentTypeIndex);
 			TemplateComponentDepot.Set(template.ID, component);
+			ComponentDepot.Register<TComponent>(componentTypeIndex);
 		}
 
-		// TODO: TEST ME!!!
 		public Entity Instantiate(in Template template)
 		{
 			var entity = EntityStorage.Create();
@@ -68,14 +78,31 @@
 			MessageDepot.Add(message);
 		}
 
+		public void Destroy(in Entity entity)
+		{
+			foreach (var componentTypeIndex in EntityStorage.ComponentTypeIndices(entity.ID))
+			{
+				ComponentDepot.Remove(entity.ID, componentTypeIndex);
+				FilterStorage.RemoveEntity(entity.ID, componentTypeIndex);
+			}
+
+			foreach (var relationTypeIndex in EntityStorage.RelationTypeIndices(entity.ID))
+			{
+				RelationDepot.UnrelateAll(entity.ID, relationTypeIndex);
+			}
+
+			EntityStorage.Destroy(entity);
+		}
+
+
 		public void FinishUpdate()
 		{
 			MessageDepot.Clear();
 		}
 
-		public WorldState CreateState()
+		public Snapshot CreateSnapshot()
 		{
-			return new WorldState();
+			return new Snapshot(this);
 		}
 	}
 }