Update archtype ecs

Ghost.ArcEntities/World.cs

@@ -0,0 +1,109 @@
+using System.Runtime.CompilerServices;
+
+namespace Ghost.ArcEntities;
+
+public partial class World
+{
+    private static List<World> s_worlds = new(4);
+    private static Queue<WorldID> s_freeWorldSlots = new();
+
+    public static int WorldCount => s_worlds.Count - s_freeWorldSlots.Count;
+
+    public static World Create(int entityCapacity = 16)
+    {
+        lock (s_worlds)
+        {
+            if (s_freeWorldSlots.TryDequeue(out var index))
+            {
+                s_worlds[index] = new World(index, entityCapacity);
+            }
+            else
+            {
+                if (s_worlds.Count >= WorldID.MaxValue)
+                {
+                    throw new InvalidOperationException("Maximum number of worlds reached");
+                }
+
+                index = (WorldID)s_worlds.Count;
+                s_worlds.Add(new World(index, entityCapacity));
+            }
+
+            return s_worlds[index];
+        }
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static World GetWorld(int index)
+    {
+        return s_worlds[index];
+    }
+}
+
+public partial class World : IDisposable, IEquatable<World>
+{
+    private readonly WorldID _id;
+
+    private bool _isDisposed = false;
+
+    public WorldID ID => _id;
+
+    private World(WorldID id, int entityCapacity)
+    {
+        _id = id;
+    }
+
+    ~World()
+    {
+        Dispose();
+    }
+
+    public bool Equals(World? other)
+    {
+        if (other is null)
+        {
+            return false;
+        }
+
+        if (ReferenceEquals(this, other))
+        {
+            return true;
+        }
+
+        return _id == other._id;
+    }
+
+    public override int GetHashCode()
+    {
+        return _id.GetHashCode();
+    }
+
+    public override bool Equals(object? obj)
+    {
+        return obj is World other && Equals(other);
+    }
+
+    public static bool operator ==(World? left, World? right)
+    {
+        return left?.Equals(right) ?? right is null;
+    }
+
+    public static bool operator !=(World? left, World? right)
+    {
+        return !(left == right);
+    }
+
+    public void Dispose()
+    {
+        if (_isDisposed)
+        {
+            return;
+        }
+
+        s_freeWorldSlots.Enqueue(_id);
+
+        _isDisposed = true;
+
+        GC.SuppressFinalize(this);
+    }
+}
+