ECS - Support QuerySystem without generic component arguments

src/ECS/Systems/BaseSystem.cs

@@ -297,7 +297,7 @@ internal virtual void AppendPerfStats(StringBuilder sb, int depth)
         sb.Append($" {Perf.LastMemory,12}");
         sb.Append($" {Perf.SumMemory,12}");
 
-        if (this is QuerySystem querySystem) {
+        if (this is QuerySystemBase querySystem) {
             sb.Append($" {querySystem.EntityCount,12}");
         }
         sb.Append('\n');

src/ECS/Systems/Extensions/SystemExtensions.cs

@@ -80,7 +80,7 @@ private static void GetGroupSystems(Archetype type, SystemGroup group, int store
                 GetGroupSystems(type, systemGroup, storeIndex, subParent, depth + 1);
                 continue;
             }
-            if (system is QuerySystem querySystem) {
+            if (system is QuerySystemBase querySystem) {
                 var query = querySystem.Queries[storeIndex];
                 if (query.IsMatch(type.ComponentTypes, type.Tags)) {
                     IncrementCount(parent);
@@ -98,7 +98,7 @@ private static void GetSystems(Archetype type, SystemGroup group, int storeIndex
                 GetSystems(type, systemGroup, storeIndex);
                 continue;
             }
-            if (system is QuerySystem querySystem) {
+            if (system is QuerySystemBase querySystem) {
                 var query = querySystem.Queries[storeIndex];
                 if (query.IsMatch(type.ComponentTypes, type.Tags)) {
                     AddMatch(new SystemMatch { system = querySystem, count = 1 });

src/ECS/Systems/Internal/Item.cs

@@ -20,7 +20,7 @@ public override string ToString()
         sb.Append(system.id);
         sb.Append(" - ");
         switch (system) {
-            case QuerySystem querySystem:
+            case QuerySystemBase querySystem:
                 sb.Append(system.Name);
                 sb.Append(" - entities: ");
                 sb.Append(querySystem.EntityCount);

src/ECS/Systems/Query/Arg.0.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Ullrich Praetz - https://github.com/friflo. All rights reserved.
+// See LICENSE file in the project root for full license information.
+
+using static System.Diagnostics.DebuggerBrowsableState;
+using Browse = System.Diagnostics.DebuggerBrowsableAttribute;
+// Hard Rule! file must not have any dependency a to a specific game engine. E.g. Unity, Godot, Monogame, ...
+
+// ReSharper disable ConvertToPrimaryConstructor
+// ReSharper disable ConvertToAutoPropertyWithPrivateSetter
+// ReSharper disable once CheckNamespace
+namespace Friflo.Engine.ECS.Systems;
+
+/// <summary>
+/// A query system returning entities with the specified component type via its <see cref="Query"/> property.
+/// </summary>
+public abstract class QuerySystem : QuerySystemBase
+{
+    /// <summary> Return all entities matching the <see cref="Query"/>. </summary>
+    protected       ArchetypeQuery      Query       => query;
+
+    public override string              ToString()  => $"{Name} - []";
+
+    #region fields
+    [Browse(Never)] private     ArchetypeQuery    query;
+    #endregion
+
+    protected QuerySystem() : base (default) { }
+
+    internal override void SetQuery(ArchetypeQuery query) { this.query = query; }
+
+    internal override ArchetypeQuery  CreateQuery(EntityStore store) {
+        return store.Query(Filter);
+    }
+}

src/ECS/Systems/Query/Arg.1.cs

@@ -13,7 +13,7 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning entities with the specified component type via its <see cref="Query"/> property.
 /// </summary>
-public abstract class QuerySystem<T1> : QuerySystem
+public abstract class QuerySystem<T1> : QuerySystemBase
     where T1 : struct, IComponent
 {
     /// <summary> Return all entities matching the <see cref="Query"/>. </summary>

src/ECS/Systems/Query/Arg.2.cs

@@ -13,7 +13,7 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning entities with the specified component types via its <see cref="Query"/> property.
 /// </summary>
-public abstract class QuerySystem<T1, T2> : QuerySystem
+public abstract class QuerySystem<T1, T2> : QuerySystemBase
     where T1 : struct, IComponent
     where T2 : struct, IComponent
 {

src/ECS/Systems/Query/Arg.3.cs

@@ -13,7 +13,7 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning entities with the specified component types via its <see cref="Query"/> property.
 /// </summary>
-public abstract class QuerySystem<T1, T2, T3> : QuerySystem
+public abstract class QuerySystem<T1, T2, T3> : QuerySystemBase
     where T1 : struct, IComponent
     where T2 : struct, IComponent
     where T3 : struct, IComponent

src/ECS/Systems/Query/Arg.4.cs

@@ -13,7 +13,7 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning entities with the specified component types via its <see cref="Query"/> property.
 /// </summary>
-public abstract class QuerySystem<T1, T2, T3, T4> : QuerySystem
+public abstract class QuerySystem<T1, T2, T3, T4> : QuerySystemBase
     where T1 : struct, IComponent
     where T2 : struct, IComponent
     where T3 : struct, IComponent

src/ECS/Systems/Query/Arg.5.cs

@@ -13,7 +13,7 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning entities with the specified component types via its <see cref="Query"/> property.
 /// </summary>
-public abstract class QuerySystem<T1, T2, T3, T4, T5> : QuerySystem
+public abstract class QuerySystem<T1, T2, T3, T4, T5> : QuerySystemBase
     where T1 : struct, IComponent
     where T2 : struct, IComponent
     where T3 : struct, IComponent

src/ECS/Systems/QuerySystem.cs → src/ECS/Systems/QueryBaseSystem.cs

@@ -16,10 +16,23 @@ namespace Friflo.Engine.ECS.Systems;
 /// <summary>
 /// A query system returning the components specified in a subclass extending <c>QuerySystem&lt;T1, ... , Tn></c>.
 /// </summary>
-public abstract class QuerySystem : BaseSystem
+public abstract class QuerySystemBase : BaseSystem
 {
 #region properties
-    /// <summary> A query filter used to restrict the entities returned by its <c>Query</c> property. </summary>
+    /// <summary>
+    /// A query filter used to restrict the entities returned by its <c>Query</c> property.<br/>
+    /// See remarks to add a tag filter to a custom <c>QuerySystem</c>.
+    /// </summary>
+    /// <remarks>
+    /// Additional tag filters can be added in the constructor of a class extending a <c>QuerySystem</c>.
+    /// <code>
+    /// class MySystem : QuerySystem&lt;Scale3>
+    /// {
+    ///     public MySystem() => Filter.AnyTags(Tags.Get&lt;MyTag>()); 
+    ///     protected override void OnUpdate() { ... }
+    /// }
+    /// </code>
+    /// </remarks>
     [Browse(Never)] public          QueryFilter         Filter          => filter;
 
     /// <summary> The number of entities matching the <c>Query</c>. </summary>
@@ -43,7 +56,7 @@ public abstract class QuerySystem : BaseSystem
     #endregion
 
 #region constructor
-    internal QuerySystem(in ComponentTypes componentTypes) {
+    internal QuerySystemBase(in ComponentTypes componentTypes) {
         this.componentTypes = componentTypes;
         queries             = new ReadOnlyList<ArchetypeQuery>(Array.Empty<ArchetypeQuery>());
     }

src/Tests/ECS/Systems/Test_QuerySystem.cs

@@ -15,12 +15,14 @@ public static class Test_QuerySystem
         [Test]
         public static void Test_QuerySystem_ToString()
         {
+            var query0 = new TestQuerySystem0();
             var query1 = new TestQuerySystem1();
             var query2 = new TestQuerySystem2();
             var query3 = new TestQuerySystem3();
             var query4 = new TestQuerySystem4();
             var query5 = new TestQuerySystem5();
 
+            AreEqual("TestQuerySystem0 - []",                                                       query0.ToString());
             AreEqual("TestQuerySystem1 - [Position]",                                               query1.ToString());
             AreEqual("TestQuerySystem2 - [Position, Scale3]",                                       query2.ToString());
             AreEqual("TestQuerySystem3 - [Position, Scale3, Rotation]",                             query3.ToString());
@@ -56,6 +58,10 @@ public static void Test_System_Enabled()
         }
     }
 
+    internal class TestQuerySystem0 : QuerySystem {
+        protected override void OnUpdate() { }
+    }
+
     internal class TestQuerySystem1 : QuerySystem<Position> {
         protected override void OnUpdate() { }
     }

src/Tests/ECS/Systems/Test_ScriptSystems.cs

@@ -15,7 +15,8 @@ public class SystemSet : Script
     private readonly    SystemRoot  Systems = new ("Systems");
 
     public override void Start() {
-        QuerySystem system = argCount switch {
+        QuerySystemBase system = argCount switch {
+            0 => new MySystem_Arg0(),
             1 => new MySystem_Arg1(),
             2 => new MySystem_Arg2(),
             3 => new MySystem_Arg3(),
@@ -32,6 +33,17 @@ public override void Update() {
     }
 }
 
+public class MySystem_Arg0 : QuerySystem
+{
+    /// <summary> Cover <see cref="ChunkEnumerator{T1}.MoveNext"/> </summary>
+    protected override void OnUpdate()
+    {
+        Mem.AreEqual(1000, Query.Count);
+        Mem.AreEqual(1000, Query.Store.Count);
+        Mem.AreEqual(1000, Query.Entities.Count);
+    }
+}
+
 public class MySystem_Arg1 : QuerySystem<Position>
 {
 
@@ -171,6 +183,24 @@ protected override void OnUpdate()
 
 public static class Test_ScriptSystems
 {
+    [Test]
+    public static void Test_ScriptSystems_query_arg_count_0()
+    {
+        var store = SetupTestStore();
+        var root  = store.StoreRoot;
+        root.AddScript(new SystemSet { argCount = 0 });
+
+        var child = store.CreateEntity();
+        root.AddChild(child);
+        for (int n = 3; n <= 1000; n++) {
+            child = child.Archetype.CreateEntity();
+            root.AddChild(child);
+        }
+        CreateSystems(store);
+        int count = 10; // 10_000_000 ~ #PC: 1575 ms
+        ExecuteSystems(store, count);
+    }
+
     [Test]
     public static void Test_ScriptSystems_query_arg_count_1()
     {