Change api to support archetypes and move stuff to different namespaces

src/Internal/Containers/PagedSparseSet.bf

@@ -0,0 +1,81 @@
+namespace Theater_ECS.Internal.Containers;
+
+using System;
+using System.Collections;
+
+class PagedSparseSet
+{
+	public const uint32 PageSize = 4096;
+
+	private List<List<Entity>> _sparse = new .()~ DeleteContainerAndItems!(_);
+	private List<Entity> _packed = new .() ~ delete _;
+	private UList _packedEntities ~ delete _;
+
+	public this(int_cosize size)
+	{
+		_packedEntities = new .(size);
+	}
+
+	public bool Contains(Entity e)
+	{
+		return _sparse[e.Index/PageSize][e.Index % PageSize] != Entity.Null;
+	}
+
+	public void Add(Entity e, void* toAdd)
+	{
+		EnsureLoadedPage(e.Index/PageSize);
+		_packed.Add(e);
+		_packedEntities.Add(toAdd);
+		_sparse[e.Index/PageSize][e.Index % PageSize] = (.)_packed.Count-1;
+	}
+
+	public void Remove(Entity e)
+	{
+		EnsurePage(e.Index/PageSize);
+		if(_sparse[e.Index/PageSize] == null)
+			return;
+
+		let toRm = _packed[_sparse[e.Index/PageSize][e.Index % PageSize].Index];
+		let b = _packed.Back;
+		_packed[_sparse[e.Index/PageSize][e.Index % PageSize].Index] = b;
+		_packed.Back = toRm;
+
+		_sparse[b.Index/PageSize][b.Index % PageSize] = Entity(e.Index, b.Version);
+		_sparse[e.Index/PageSize][e.Index % PageSize] = Entity.Null;
+
+		_packed.PopBack();
+	}
+
+	[Inline, Unchecked]
+	public void* Get(Entity e)
+	{
+		return _packedEntities[(.)(_sparse[e.Index/PageSize][e.Index % PageSize].Index)];
+	}
+
+	public Span<Entity> GetAll()
+	{
+		return _packed;
+	}
+
+	public int_cosize Count() => (.)_packed.Count;
+
+	///Ensure that a page exist and is loaded
+	public void EnsureLoadedPage(uint32 page)
+	{
+		EnsurePage(page);
+		if(_sparse[page] == null)
+		{
+			_sparse[page] = new List<Entity>(PageSize);
+			_sparse[page].[Friend]Count = 4096;
+			_sparse[page].SetAll(Entity.Null);
+
+		}
+	}
+
+	///Ensure that a page exists, it might be null though
+	private void EnsurePage(uint32 page)
+	{
+		while(_sparse.Count < page+1)
+			_sparse.Add(null);
+	}
+}