Add .Lookup and .MaybeGet

src/gaemstone/ECS/EntityBase.cs

@@ -11,6 +11,8 @@ public abstract class EntityBase<TReturn>
 	public abstract bool Has(Identifier id);
 
 	public abstract T Get<T>();
+	public abstract T? MaybeGet<T>() where T : unmanaged;
+	public abstract T? MaybeGet<T>(T _ = null!) where T : class;
 	public abstract ref T GetRef<T>() where T : unmanaged;
 	public abstract void Modified<T>();
 

src/gaemstone/ECS/EntityBuilder.cs

@@ -68,6 +68,8 @@ public class EntityBuilder
 			: throw new NotSupportedException(); // TODO: Support wildcard.
 
 	public override T Get<T>() => throw new NotSupportedException();
+	public override T? MaybeGet<T>() => throw new NotSupportedException();
+	public override T? MaybeGet<T>(T _ = null!) where T : class => throw new NotSupportedException();
 	public override ref T GetRef<T>() => throw new NotSupportedException();
 	public override void Modified<T>() => throw new NotImplementedException();
 

src/gaemstone/ECS/EntityRef.cs

@@ -19,14 +19,18 @@ public unsafe sealed class EntityRef
 
 	public string? Name {
 		get => ecs_get_name(Universe, this).FlecsToString()!;
-		set { using var alloc = TempAllocator.Use(); ecs_set_name(Universe, this, alloc.AllocateCString(value)); }
+		set { using var alloc = TempAllocator.Use();
+		      ecs_set_name(Universe, this, alloc.AllocateCString(value)); }
 	}
 	public string? Symbol {
 		get => ecs_get_symbol(Universe, this).FlecsToString()!;
-		set { using var alloc = TempAllocator.Use(); ecs_set_symbol(Universe, this, alloc.AllocateCString(value)); }
+		set { using var alloc = TempAllocator.Use();
+		      ecs_set_symbol(Universe, this, alloc.AllocateCString(value)); }
 	}
 
-	// TODO: public IEnumerable<Entity> Children => ...
+	// public IEnumerable<Entity> Children { get {
+	//
+	// } }
 
 	public EntityRef(Universe universe, Entity entity, bool throwOnInvalid = true)
 	{
@@ -41,6 +45,11 @@ public unsafe sealed class EntityRef
 
 	public EntityBuilder NewChild(EntityPath? path = null)
 		=> Universe.New(EnsureRelativePath(path)).ChildOf(this);
+	public EntityRef? Lookup(EntityPath path)
+		=> Universe.Lookup(this, EnsureRelativePath(path)!);
+	public EntityRef LookupOrThrow(EntityPath path)
+		=> Universe.LookupOrThrow(this, EnsureRelativePath(path)!);
+
 	private static EntityPath? EnsureRelativePath(EntityPath? path)
 		{ if (path?.IsAbsolute == true) throw new ArgumentException("path must not be absolute", nameof(path)); return path; }
 
@@ -53,10 +62,25 @@ public unsafe sealed class EntityRef
 		var comp = Universe.LookupOrThrow<T>();
 		var ptr  = ecs_get_id(Universe, this, comp);
 		if (ptr == null) throw new Exception($"Component {typeof(T)} not found on {this}");
-		return (typeof(T).IsValueType) ? Unsafe.Read<T>(ptr)
+		return typeof(T).IsValueType ? Unsafe.Read<T>(ptr)
 			: (T)((GCHandle)Unsafe.Read<nint>(ptr)).Target!;
 	}
 
+	public override T? MaybeGet<T>()
+	{
+		var comp = Universe.LookupOrThrow<T>();
+		var ptr  = ecs_get_id(Universe, this, comp);
+		return (ptr != null) ? Unsafe.Read<T>(ptr) : null;
+	}
+
+	public override T? MaybeGet<T>(T _ = null!)
+		where T : class
+	{
+		var comp = Universe.LookupOrThrow<T>();
+		var ptr  = ecs_get_id(Universe, this, comp);
+		return (ptr != null) ? (T)((GCHandle)Unsafe.Read<nint>(ptr)).Target! : null;
+	}
+
 	public override ref T GetRef<T>()
 	{
 		var comp = Universe.LookupOrThrow<T>();