Add ComponentIndex<,>

src/ECS/Index/ComponentIndex.cs

@@ -0,0 +1,63 @@
+using System.Collections.Generic;
+using Friflo.Engine.ECS.Index;
+
+// ReSharper disable once CheckNamespace
+namespace Friflo.Engine.ECS;
+
+public readonly struct ComponentIndex <TIndexedComponent,TValue>
+    where TIndexedComponent : struct, IIndexedComponent<TValue>
+{
+    private readonly AbstractComponentIndex<TValue> index;
+
+    internal ComponentIndex(AbstractComponentIndex<TValue> index) {
+        this.index = index;
+    }
+
+    /// <summary>
+    /// Return the entities having a component with the passed component value.<br/>
+    /// Executes in O(1) with default index. 
+    /// </summary>
+    public Entities this[TValue value] => index.GetHasValueEntities(value);
+
+    /// <summary>
+    /// Returns all indexed component values of the passed <typeparamref name="TIndexedComponent"/> type.<br/>
+    /// Executes in O(1). Each value in the returned list is unique. See remarks for additional infos.
+    /// </summary>
+    /// <remarks>
+    /// <list type="bullet">
+    ///   <item>
+    ///     The returned collection changes when indexed component values are updated, removed or added.
+    ///   </item>
+    ///   <item>
+    ///     To get the entities having a specific component value use <see cref="this[TValue]"/>.
+    ///   </item>
+    ///   <item>
+    ///     If <typeparamref name="TValue"/> is a class all collection values are not null.<br/>
+    ///     Use <see cref="this[TValue]"/> to check if null is indexed.
+    ///   </item>
+    /// </list>
+    /// </remarks>
+    public IReadOnlyCollection<TValue> Values => index.IndexedComponentValues;
+
+    /// <summary>
+    /// Returns all entities linked by the specified <see cref="ILinkComponent"/> type.<br/>
+    /// Executes in O(1). Each entity in the returned list is unique. See remarks for additional infos.
+    /// </summary>
+    /// <remarks>
+    /// <list type="bullet">
+    ///   <item>
+    ///     The returned collection changes when component link values are updated, removed or added.
+    ///   </item>
+    ///   <item>
+    ///     To get the entities linking a specific entity use <see cref="IndexExtensions.GetIncomingLinks{TComponent}"/>.<br/>
+    ///   </item>
+    ///   <item>
+    ///     The method is a specialized version of <see cref="Values"/><br/>
+    ///     using <c> TIndexedComponent = ILinkComponent</c> and <c>TValue = Entity</c>.  
+    ///   </item>
+    /// </list>
+    /// </remarks>
+    public IReadOnlyCollection<Entity> LinkedEntities => ((AbstractComponentIndex<Entity>)(object)index).IndexedComponentValues;
+
+    public override string ToString() => $"Count: {Values.Count}";
+}

src/ECS/Index/IIndexedComponent.cs

@@ -16,7 +16,7 @@ namespace Friflo.Engine.ECS;
 ///   </item>
 ///   <item>
 ///     Return all entities with a component field of a specific value. <br/>
-///     See <see cref="IndexExtensions.GetEntitiesWithComponentValue{TIndexedComponent,TValue}"/>.
+///     See <see cref="ComponentIndex{TIndexedComponent,TValue}.this[TValue]"/>.
 ///   </item>
 ///   <item>
 ///     Return a collection of all unique component values.<br/>

src/ECS/Index/IndexExtensions.cs

@@ -31,6 +31,18 @@ public static EntityLinks<TComponent> GetIncomingLinks<TComponent>(this Entity t
 
 #region EntityStore
     /// <summary>
+    /// Returns the index for indexed components to search entities with a specific component value in O(1).<br/>
+    /// Executes in O(1). 
+    /// </summary>
+    public static ComponentIndex<TIndexedComponent,TValue> ComponentIndex<TIndexedComponent, TValue>(this EntityStore store)
+        where TIndexedComponent: struct, IIndexedComponent<TValue>
+    {
+        var index = (AbstractComponentIndex<TValue>)StoreIndex.GetIndex(store, StructInfo<TIndexedComponent>.Index);
+        return new ComponentIndex<TIndexedComponent, TValue>(index);
+    }
+
+    /// <summary>
+    /// Obsolete: Use <see cref="ComponentIndex{TIndexedComponent,TValue}.this[TValue]"/><br/>
     /// Return the entities with the passed component value.<br/>
     /// Executes in O(1) with default index. 
     /// </summary>
@@ -42,6 +54,7 @@ public static Entities GetEntitiesWithComponentValue<TComponent, TValue>(this En
     }
 
     /// <summary>
+    /// Obsolete: Use <see cref="ComponentIndex{TIndexedComponent,TValue}.Values"/><br/>
     /// Returns all indexed component values of the passed <typeparamref name="TComponent"/> type.<br/>
     /// Executes in O(1). Each value in the returned list is unique. See remarks for additional infos.
     /// </summary>
@@ -51,11 +64,11 @@ public static Entities GetEntitiesWithComponentValue<TComponent, TValue>(this En
     ///     The returned collection changes when indexed component values are updated, removed or added.
     ///   </item>
     ///   <item>
-    ///     To get the entities having a specific component value use <see cref="GetEntitiesWithComponentValue{TComponent,TValue}"/>.
+    ///     To get the entities having a specific component value use <see cref="ComponentIndex{TIndexedComponent,TValue}.this[TValue]"/>.
     ///   </item>
     ///   <item>
     ///     If <typeparamref name="TValue"/> is a class all collection values are not null.<br/>
-    ///     Use <see cref="GetEntitiesWithComponentValue{TComponent,TValue}"/> to check if null is referenced.
+    ///     Use <see cref="ComponentIndex{TIndexedComponent,TValue}.this[TValue]"/> to check if null is referenced.
     ///   </item>
     /// </list>
     /// </remarks>
@@ -67,6 +80,7 @@ public static  IReadOnlyCollection<TValue> GetAllIndexedComponentValues<TCompone
     }
 
     /// <summary>
+    /// Obsolete: Use <see cref="ComponentIndex{TIndexedComponent,TValue}.LinkedEntities"/><br/>
     /// Returns all entities linked by the specified <see cref="ILinkComponent"/> type.<br/>
     /// Executes in O(1). Each entity in the returned list is unique. See remarks for additional infos.
     /// </summary>
@@ -79,8 +93,8 @@ public static  IReadOnlyCollection<TValue> GetAllIndexedComponentValues<TCompone
     ///     To get the entities linking a specific entity use <see cref="GetIncomingLinks{TComponent}"/>.<br/>
     ///   </item>
     ///   <item>
-    ///     The method is a specialized version of <see cref="GetAllIndexedComponentValues{TComponent,TValue}"/><br/>
-    ///     using <c> TComponent = ILinkComponent</c> and <c>TValue = Entity</c>.  
+    ///     The method is a specialized version of <see cref="ComponentIndex{TIndexedComponent,TValue}.Values"/><br/>
+    ///     using <c> TIndexedComponent = ILinkComponent</c> and <c>TValue = Entity</c>.  
     ///   </item>
     /// </list>
     /// </remarks>

src/Tests/ECS/Examples/Component_Types.cs

@@ -1,6 +1,7 @@
 using Friflo.Engine.ECS;
 using NUnit.Framework;
 
+// ReSharper disable UnusedVariable
 // ReSharper disable NotAccessedField.Local
 // ReSharper disable ArrangeTypeMemberModifiers
 // ReSharper disable InconsistentNaming
@@ -171,12 +172,13 @@ struct Player : IIndexedComponent<string>       // indexed field type: string
 public static void IndexedComponents()
 {
     var store   = new EntityStore();
+    var index   = store.ComponentIndex<Player,string>();
     for (int n = 0; n < 1000; n++) {
         var entity = store.CreateEntity();
         entity.AddComponent(new Player { name = $"Player-{n,0:000}"});
     }
     // get all entities where Player.name == "Player-001". O(1)
-    store.GetEntitiesWithComponentValue<Player,string>("Player-001");      // Count: 1
+    var entities = index["Player-001"];                                    // Count: 1
 
     // return same result as lookup using a Query(). O(1)
     store.Query().HasValue    <Player,string>("Player-001");               // Count: 1
@@ -186,7 +188,7 @@ public static void IndexedComponents()
     store.Query().ValueInRange<Player,string>("Player-000", "Player-099"); // Count: 100
 
     // get all unique Player.name's. O(1)
-    store.GetAllIndexedComponentValues<Player,string>();                   // Count: 1000
+    var values = index.Values;                                             // Count: 1000
 }
 
 #endregion

src/Tests/ECS/Github/Test_GitHub_15.cs

@@ -23,18 +23,20 @@ public static void Test_GitHub_15_update_indexed_components_on_deserialization()
             var entityB = store.CreateEntity(2);
             entityB.AddComponent(new IndexedInt { value = 12 });
 
-            AreEqual(1, store.GetEntitiesWithComponentValue<IndexedInt,int>(11).Count);
-            AreEqual(2, store.GetAllIndexedComponentValues<IndexedInt,int>().Count);
+            var index = store.ComponentIndex<IndexedInt,int>();
+            AreEqual(1, index[11].Count);
+            AreEqual(2, index.Values.Count);
 
             using var stream = new MemoryStream();
             var serializer = new EntitySerializer();
             serializer.WriteStore(store, stream);
 
             var readStore = new EntityStore();
+            var readIndex = readStore.ComponentIndex<IndexedInt,int>();
             serializer.ReadIntoStore(readStore, stream);
             AreEqual(2, readStore.Count);
-            AreEqual(1, readStore.GetEntitiesWithComponentValue<IndexedInt,int>(11).Count);
-            AreEqual(2, readStore.GetAllIndexedComponentValues<IndexedInt,int>().Count);
+            AreEqual(1, readIndex[11].Count);
+            AreEqual(2, readIndex.Values.Count);
         }
     }
 }