Generalize optional references and init data

Added extension methods to query data from ECS objects
Added base class for ECS objects
Added support for representing in-construction ECS objects with an OptionalRef<T>

TechbloxModdingAPI/Block.cs

@@ -20,7 +20,7 @@ namespace TechbloxModdingAPI
 	/// A single (perhaps scaled) block. Properties may return default values if the block is removed and then setting them is ignored.
 	/// For specific block type operations, use the specialised block classes in the TechbloxModdingAPI.Blocks namespace.
 	/// </summary>
-	public class Block : IEquatable<Block>, IEquatable<EGID>
+	public class Block : EcsObjectBase, IEquatable<Block>, IEquatable<EGID>
 	{
 		protected static readonly PlacementEngine PlacementEngine = new PlacementEngine();
 		protected static readonly MovementEngine MovementEngine = new MovementEngine();
@@ -78,8 +78,7 @@ namespace TechbloxModdingAPI
 				var initializer = PlacementEngine.PlaceBlock(block, position, player, autoWire);
 				var egid = initializer.EGID;
 				var bl = New<T>(egid.entityID, egid.groupID);
-				bl.InitData.Group = BlockEngine.InitGroup(initializer);
+				bl.InitData = initializer;
-				bl.InitData.Reference = initializer.reference;
 				Placed += bl.OnPlacedInit;
 				return bl;
 			}
@@ -241,13 +240,12 @@ namespace TechbloxModdingAPI
 				throw new BlockException("Blocks can only be placed in build mode.");
 			var initializer = PlacementEngine.PlaceBlock(type, position, player, autoWire);
 			Id = initializer.EGID;
-			InitData.Group = BlockEngine.InitGroup(initializer);
+			InitData = initializer;
 			Placed += OnPlacedInit;
 		}
 
-		public EGID Id { get; }
+		public override EGID Id { get; }
 
-		internal BlockEngine.BlockInitData InitData;
 		private EGID copiedFrom;
 
 		/// <summary>

TechbloxModdingAPI/Blocks/BlockEngine.cs

@@ -9,6 +9,7 @@ using RobocraftX.Blocks;
 using RobocraftX.Common;
 using RobocraftX.Physics;
 using RobocraftX.Rendering;
+using RobocraftX.Rendering.GPUI;
 using Svelto.ECS.EntityStructs;
 
 using Svelto.DataStructures;
@@ -16,6 +17,7 @@ using Svelto.ECS;
 using Svelto.ECS.Hybrid;
 using Unity.Mathematics;
 using TechbloxModdingAPI.Engines;
+using TechbloxModdingAPI.Utility;
 
 namespace TechbloxModdingAPI.Blocks
 {
@@ -68,14 +70,13 @@ namespace TechbloxModdingAPI.Blocks
 			: entitiesDB.QueryEntity<PaletteEntryEntityStruct>(index,
 				CommonExclusiveGroups.COLOUR_PALETTE_GROUP).Colour;
 
-		public ref T GetBlockInfo<T>(EGID blockID) where T : unmanaged, IEntityComponent
+		public OptionalRef<T> GetBlockInfo<T>(EGID blockID) where T : unmanaged, IEntityComponent
 		{
-			if (entitiesDB.Exists<T>(blockID))
+			return entitiesDB.TryQueryEntitiesAndIndex<T>(blockID, out uint index, out var array)
-				return ref entitiesDB.QueryEntity<T>(blockID);
+				? new OptionalRef<T>(array, index)
-			T[] structHolder = new T[1]; //Create something that can be referenced
+				: new OptionalRef<T>();
-			return ref structHolder[0]; //Gets a default value automatically
 		}
-		
+
 		public ref T GetBlockInfoViewStruct<T>(EGID blockID) where T : struct, INeedEGID, IEntityViewComponent
 		{
 			if (entitiesDB.Exists<T>(blockID))
@@ -149,6 +150,12 @@ namespace TechbloxModdingAPI.Blocks
 			entitiesDB.QueryEntity<RenderingDataStruct>(id).matrix = float4x4.TRS(pos.position, rot.rotation, scale.scale);
 		}
 
+        internal void UpdatePrefab(Block block, ushort type, byte material, bool flipped)
+        {
+            uint pid = PrefabsID.GetOrCreatePrefabID(type, material, 0, flipped);
+            entitiesDB.QueryEntityOrDefault<GFXPrefabEntityStructGPUI>()
+        }
+
 		public bool BlockExists(EGID blockID)
 		{
 			return entitiesDB.Exists<DBEntityStruct>(blockID);

TechbloxModdingAPI/EcsObjectBase.cs

@@ -1,33 +1,43 @@
-using System;
+using System;
 using System.Linq.Expressions;
-
 using Svelto.DataStructures;
 using Svelto.ECS;
 using Svelto.ECS.Internal;
+using TechbloxModdingAPI.Blocks;
 
-namespace TechbloxModdingAPI.Blocks
+namespace TechbloxModdingAPI
 {
-    public partial class BlockEngine
+    public abstract class EcsObjectBase
     {
+        public abstract EGID Id { get; } //Abstract to support the 'place' Block constructor
+        
+        protected internal EcsInitData InitData;
+        
         /// <summary>
         /// Holds information needed to construct a component initializer
         /// </summary>
-        internal struct BlockInitData
+        protected internal struct EcsInitData
         {
-            public FasterDictionary<RefWrapperType, ITypeSafeDictionary> Group;
+            private FasterDictionary<RefWrapperType, ITypeSafeDictionary> group;
-            public EntityReference Reference;
+            private EntityReference reference;
+
+            public static implicit operator EcsInitData(EntityInitializer initializer) => new EcsInitData
+                {group = GetInitGroup(initializer), reference = initializer.reference};
+
+            public EntityInitializer Initializer(EGID id) => new EntityInitializer(id, group, reference);
+            public bool Valid => group != null;
         }
 
-        internal delegate FasterDictionary<RefWrapperType, ITypeSafeDictionary> GetInitGroup(
+        private delegate FasterDictionary<RefWrapperType, ITypeSafeDictionary> GetInitGroupFunc(
             EntityInitializer initializer);
 
         /// <summary>
         /// Accesses the group field of the initializer
         /// </summary>
-        internal GetInitGroup InitGroup = CreateAccessor<GetInitGroup>("_group");
+        private static GetInitGroupFunc GetInitGroup = CreateAccessor<GetInitGroupFunc>("_group");
 
         //https://stackoverflow.com/questions/55878525/unit-testing-ref-structs-with-private-fields-via-reflection
-        internal static TDelegate CreateAccessor<TDelegate>(string memberName) where TDelegate : Delegate
+        private static TDelegate CreateAccessor<TDelegate>(string memberName) where TDelegate : Delegate
         {
             var invokeMethod = typeof(TDelegate).GetMethod("Invoke");
             if (invokeMethod == null)

TechbloxModdingAPI/Utility/ApiExtensions.cs

@@ -0,0 +1,53 @@
+using Svelto.ECS;
+using TechbloxModdingAPI.Blocks;
+
+namespace TechbloxModdingAPI.Utility
+{
+    public static class ApiExtensions
+    {
+        /// <summary>
+        /// Attempts to query an entity and returns an optional that contains the result if succeeded.
+        /// </summary>
+        /// <param name="entitiesDB">The entities DB</param>
+        /// <param name="egid">The EGID to query</param>
+        /// <typeparam name="T">The component type to query</typeparam>
+        /// <returns>An optional that contains the result on success or is empty if not found</returns>
+        public static OptionalRef<T> QueryEntityOptional<T>(this EntitiesDB entitiesDB, EGID egid)
+            where T : unmanaged, IEntityComponent
+        {
+            return entitiesDB.TryQueryEntitiesAndIndex<T>(egid, out uint index, out var array)
+                ? new OptionalRef<T>(array, index)
+                : new OptionalRef<T>(); 
+        }
+
+        /// <summary>
+        /// Attempts to query an entity and returns the result or a dummy value that can be modified.
+        /// </summary>
+        /// <param name="entitiesDB"></param>
+        /// <param name="obj"></param>
+        /// <typeparam name="T"></typeparam>
+        /// <returns></returns>
+        public static OptionalRef<T> QueryEntityOptional<T>(this EntitiesDB entitiesDB, EcsObjectBase obj)
+            where T : unmanaged, IEntityComponent
+        {
+            var opt = QueryEntityOptional<T>(entitiesDB, obj.Id);
+            return opt ? opt : new OptionalRef<T>(obj);
+        }
+
+        /// <summary>
+        /// Attempts to query an entity and returns the result or a dummy value that can be modified.
+        /// </summary>
+        /// <param name="entitiesDB"></param>
+        /// <param name="obj"></param>
+        /// <typeparam name="T"></typeparam>
+        /// <returns></returns>
+        public static ref T QueryEntityOrDefault<T>(this EntitiesDB entitiesDB, EcsObjectBase obj)
+            where T : unmanaged, IEntityComponent
+        {
+            var opt = QueryEntityOptional<T>(entitiesDB, obj.Id);
+            if (opt) return ref opt.Get();
+            if (obj.InitData.Valid) return ref obj.InitData.Initializer(obj.Id).GetOrCreate<T>();
+            return ref opt.Get(); //Default value
+        }
+    }
+}

TechbloxModdingAPI/Utility/OptionalRef.cs

@@ -9,31 +9,51 @@ using Svelto.ECS;
 
 namespace TechbloxModdingAPI
 {
-    public struct OptionalRef<T> where T : unmanaged
+    public ref struct OptionalRef<T> where T : unmanaged, IEntityComponent
     {
         private bool exists;
         private NB<T> array;
         private uint index;
+        private EntityInitializer initializer;
 
         public OptionalRef(NB<T> array, uint index)
         {
             exists = true;
             this.array = array;
             this.index = index;
+            initializer = default;
         }
-
+        
-        public OptionalRef(ref T value)
+        /// <summary>
+        /// Wraps the initializer data, if present.
+        /// </summary>
+        /// <param name="obj">The object with the initializer</param>
+        public OptionalRef(EcsObjectBase obj)
         {
-            exists = true;
+            if (obj.InitData.Valid)
+            {
+                initializer = obj.InitData.Initializer(obj.Id);
+                exists = true;
+            }
+            else
+            {
+                initializer = default;
+                exists = false;
+            }
             array = default;
             index = default;
         }
 
-        public ref T Get(T def = default)
+        /// <summary>
+        /// Returns the value or a default value if empty. Supports objects that are being initialized.
+        /// </summary>
+        /// <returns>The value or the default value</returns>
+        public ref T Get()
         {
-            if (exists)
+            if (!exists) return ref CompRefCache<T>.Default;
+            if (initializer.EGID == EGID.Empty)
                 return ref array[index];
-            return ref CompRefCache<T>._default;
+            return ref initializer.GetOrCreate<T>();
         }
 
         public bool Exists => exists;
@@ -51,10 +71,10 @@ namespace TechbloxModdingAPI
         /// <summary>
         /// Creates an instance of a struct T that can be referenced.
         /// </summary>
-        /// <typeparam name="T">The struct type to cache</typeparam>
+        /// <typeparam name="TR">The struct type to cache</typeparam>
-        private struct CompRefCache<T> where T : unmanaged
+        private struct CompRefCache<TR> where TR : unmanaged
         {
-            public static T _default;
+            public static TR Default;
         }
     }
 }