Add EcsId.Entity / Pair and related changes

src/gaemstone.Bloxel/Client/ChunkMeshGenerator.cs

@@ -45,9 +45,9 @@ public void OnUnload()
 
 		public void OnUpdate(double delta)
 		{
-			var generated = new List<(EcsId, Mesh?)>();
+			var generated = new List<(EcsId.Entity, Mesh?)>();
 			Game.Queries.Run(without: Game.Type(typeof(Mesh)), action:
-				(EcsId entity, Chunk chunk, ChunkPaletteStorage<Prototype> storage) =>
+				(EcsId.Entity entity, Chunk chunk, ChunkPaletteStorage<Prototype> storage) =>
 					generated.Add((entity, Generate(chunk.Position, storage))));
 			foreach (var (entity, mesh) in generated) {
 				if (mesh is Mesh m) Game.Set(entity, m);

src/gaemstone.Bloxel/Prototype.cs

@@ -4,9 +4,8 @@ namespace gaemstone.Bloxel
 {
 	public readonly struct Prototype
 	{
-		public readonly EcsId Value { get; }
-		public Prototype(EcsId value) => Value = value;
-		public static implicit operator Prototype(in EcsId value) => new(value);
-		public static implicit operator EcsId(in Prototype prototype) => prototype.Value;
+		public readonly EcsId.Entity Value { get; }
+		public Prototype(EcsId.Entity value) => Value = value;
+		public static implicit operator Prototype(in EcsId.Entity value) => new(value);
 	}
 }

src/gaemstone.Common/ECS/EcsId+Entity.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace gaemstone.ECS
+{
+	public readonly partial struct EcsId
+	{
+		[StructLayout(LayoutKind.Explicit)]
+		public readonly struct Entity
+			: IEquatable<Entity>
+			, IComparable<Entity>
+		{
+			/// <summary>
+			/// A special entity value that represents "no entity".
+			/// There may never be an entity alive with this value.
+			/// This is equal to using <c>default(EcsEntity)</c>.
+			/// </summary>
+			public static readonly Entity None = default;
+
+
+			/// <summary>
+			/// The internal 64-bit value representing this entity.
+			/// </summary>
+			[FieldOffset(0)] public readonly ulong Value;
+
+			/// <summary>
+			/// The unique 32-bit integer identifier for this entity.
+			/// Only one (alive) entity may have this identifier at a time.
+			/// </summary>
+			[FieldOffset(0)] public readonly uint ID;
+
+			/// <summary>
+			/// The generation of this entitiy.
+			/// This is increased each time an entity is destroyed.
+			/// </summary>
+			[FieldOffset(4)] public readonly ushort Generation;
+
+
+			public bool IsNone => ID == 0;
+
+
+			public Entity(ulong value) : this()
+			{
+				const ulong UNUSED_MASK = 0x00FF_0000_0000_0000;
+				const ulong ROLE_MASK   = 0xFF00_0000_0000_0000;
+				if ((value & UNUSED_MASK) != 0L) throw new ArgumentException("Value has unused bits set", nameof(value));
+				if ((value &   ROLE_MASK) != 0L) throw new ArgumentException("Value has role bits set", nameof(value));
+				Value = value;
+			}
+
+			public Entity(uint id, ushort generation) : this()
+			{
+				if (id == 0) throw new ArgumentException("ID must be greater than 0", nameof(id));
+				ID = id; Generation = generation;
+			}
+
+
+			public bool Equals(Entity other) => Value == other.Value;
+			public override bool Equals(object? obj) => (obj is Entity other) && Equals(other);
+			public override int GetHashCode() => HashCode.Combine(Value);
+
+			public static bool operator ==(Entity left, Entity right) =>  left.Equals(right);
+			public static bool operator !=(Entity left, Entity right) => !left.Equals(right);
+
+			public int CompareTo(Entity other) => Value.CompareTo(other.Value);
+
+			public override string ToString() => $"Entity(Id=0x{ID:X},Generation=0x{Generation:X})";
+		}
+	}
+}

src/gaemstone.Common/ECS/EcsId+Pair.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace gaemstone.ECS
+{
+	public readonly partial struct EcsId
+	{
+		public readonly struct Pair
+			: IEquatable<Pair>
+			, IComparable<Pair>
+		{
+			public readonly ulong Value;
+
+			public uint Target   => (uint)Value;
+			public uint Relation => (uint)((Value >> 32) & 0xFFFFFF);
+
+
+			public Pair(ulong value) : this()
+			{
+				if (Value >> 56 != (ulong)EcsRole.Pair) throw new ArgumentException(
+					"Role bits must be set to EcsRole.Pair", nameof(value));
+				Value = value;
+			}
+
+			public Pair(uint relation, uint target)
+			{
+				if (relation > 0xFFFFFF) throw new ArgumentOutOfRangeException(nameof(relation),
+					relation, "Relation must fit into 24 bits (be smaller or equal to 0xFFFFFF");
+				Value = (ulong)target | (relation << 32) | ((ulong)EcsRole.Pair << 56);
+			}
+
+
+			public bool Equals(Pair other) => Value == other.Value;
+			public override bool Equals(object? obj) => (obj is Pair other) && Equals(other);
+			public override int GetHashCode() => HashCode.Combine(Value);
+
+			public static bool operator ==(Pair left, Pair right) =>  left.Equals(right);
+			public static bool operator !=(Pair left, Pair right) => !left.Equals(right);
+
+			public int CompareTo(Pair other) => Value.CompareTo(other.Value);
+
+			public override string ToString() => $"Pair(Target=0x{Target:X},Relation=0x{Relation:X})";
+		}
+	}
+}

src/gaemstone.Common/ECS/EcsId.cs

@@ -1,119 +1,51 @@
 using System;
 using System.Runtime.InteropServices;
-using System.Text;
 
 namespace gaemstone.ECS
 {
-	//         ID       Generation    Role
-	// |-------32-------|---16---|###|-8-|
-	// ===================================
-	// |   Low 32 bits  |  High 32 bits  |
-	// ===================================
-
-	// When Role == Pair, this is the layout:
-	//       Target        Relation   Role
-	// |-------32-------|-----24-----|###|
-
 	[StructLayout(LayoutKind.Explicit)]
-	public readonly struct EcsId
+	public readonly partial struct EcsId
 		: IEquatable<EcsId>
 		, IComparable<EcsId>
 	{
-		public static readonly EcsId None = default;
-
 		[FieldOffset(0)] public readonly ulong Value;
 
-		[FieldOffset(0)] public readonly uint Low;
-		[FieldOffset(4)] public readonly uint High;
-
-		[FieldOffset(0)] public readonly uint ID;
-		[FieldOffset(4)] public readonly ushort Generation;
 		[FieldOffset(7)] public readonly EcsRole Role;
 
-		public bool IsNone => (ID == 0);
+
+		[FieldOffset(0)] readonly Entity _asEntity;
+		[FieldOffset(0)] readonly Pair   _asPair;
+
 
 		EcsId(ulong value) : this() => Value = value;
-		EcsId(uint low, uint high) : this() { Low = low; High = high; }
 
-		public EcsId(uint id) : this(id, 0, EcsRole.None) {  }
-		public EcsId(uint id, EcsRole role) : this(id, 0, role) {  }
-		public EcsId(uint id, ushort generation) : this(id, generation, EcsRole.None) {  }
-		public EcsId(uint id, ushort generation, EcsRole role) : this()
-		{
-			if (id == 0) throw new ArgumentOutOfRangeException(nameof(id), "ID must be greater than 0 to be valid.");
-			ID = id; Generation = generation; Role = role;
-		}
 
-		public static EcsId Pair(uint relation, uint target)
-			=> new(target | (relation & 0xFFFFFF) << 32 | (ulong)EcsRole.Pair << 56);
-		public static EcsId Pair(EcsId relation, EcsId target)
-			=> Pair(target.ID, relation.ID);
-		public (uint Relation, uint Target) ToPair()
-			=> (High & 0xFFFFFF, Low);
-		public (EcsId Relation, EcsId Target) ToPair(Universe context)
-		{
-			var (relationId, targetId) = ToPair();
-			if (!context.Entities.TryLookup(relationId, out var relation)) throw new EntityNotFoundException(relationId);
-			if (!context.Entities.TryLookup(targetId  , out var target  )) throw new EntityNotFoundException(targetId);
-			return (relation, target);
-		}
+		public static implicit operator EcsId(Entity entity) => new(entity.Value);
+		public static implicit operator EcsId(Pair   pair  ) => new(pair.Value);
+
+		public Entity? AsEntity() => (Role == EcsRole.Entity) ? _asEntity : null;
+		public Pair?   AsPair  () => (Role == EcsRole.Pair  ) ? _asPair   : null;
 
 
 		public bool Equals(EcsId other) => Value == other.Value;
 		public override bool Equals(object? obj) => (obj is EcsId other) && Equals(other);
 		public override int GetHashCode() => Value.GetHashCode();
 
-		public static bool operator ==(EcsId left, EcsId right) => left.Equals(right);
+		public static bool operator ==(EcsId left, EcsId right) =>  left.Equals(right);
 		public static bool operator !=(EcsId left, EcsId right) => !left.Equals(right);
 
 		public int CompareTo(EcsId other) => Value.CompareTo(other.Value);
 
-
-		public override string ToString()
-		{
-			var builder = new StringBuilder();
-			AppendString(builder);
-			return builder.ToString();
-		}
-		public void AppendString(StringBuilder builder)
-		{
-			if (Role == EcsRole.Pair) {
-				builder.Append($"EcsId.Pair(relation: 0x{High & 0xFFFFFF:X}, target: 0x{Low:X})");
-			} else {
-				builder.Append($"EcsId(id: 0x{ID:X}");
-				if (Generation != 0) builder.Append($", generation: {Generation}");
-				if (Role != EcsRole.None) builder.Append($", role: {Role}");
-				builder.Append(')');
-			}
-		}
-
-		public string ToString(Universe context)
-		{
-			var builder = new StringBuilder();
-			AppendString(builder, context);
-			return builder.ToString();
-		}
-		public void AppendString(StringBuilder builder, Universe context)
-		{
-			if (Role == EcsRole.Pair) {
-				var (relationId, targetId) = ToPair();
-				builder.Append('(');
-				if (context.Entities.TryLookup(relationId, out var relation)) relation.AppendString(builder);
-				else builder.Append($"0x{relationId:X}");
-				builder.Append(",");
-				if (context.Entities.TryLookup(targetId, out var target)) target.AppendString(builder);
-				else builder.Append($"0x{targetId:X}");
-				builder.Append(')');
-			} else if (context.TryGet<Identifier>(this, out var identifier))
-				builder.Append(identifier);
-			else
-				AppendString(builder);
-		}
+		public override string ToString() => Role switch {
+			EcsRole.Entity => _asEntity.ToString(),
+			EcsRole.Pair   => _asPair.ToString(),
+			_ => $"EcsId(Value=0x{Value:X},Role={Role})"
+		};
 	}
 
 	public enum EcsRole : byte
 	{
-		None,
+		Entity,
 		Pair,
 	}
 }