ECS - Allow usage of Entity.Equals(object) and Entity.GetHashCode()

before: throws NotImplementedException("to avoid excessive boxing. Use Id or EntityUtils.EqualityComparer")
friflo · Jan 26, 2025 · e1f2cfd · e1f2cfd
1 parent b3b0252
commit e1f2cfd
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Showing 3 changed files with 60 additions and 18 deletions.
diff --git a/src/ECS/Entity.cs b/src/ECS/Entity.cs
@@ -664,13 +664,16 @@ internal bool TryGetTreeNode(out TreeNode treeNode)
     public          bool    Equals(Entity other)                => rawEntity == other.rawEntity && store == other.store;
 
     // --- object
-    /// <summary> Note: Not implemented to avoid excessive boxing. </summary>
-    /// <remarks> Use <see cref="operator=="/> or <see cref="EntityUtils.EqualityComparer"/> </remarks>
-    public override bool    Equals(object obj)  => throw EntityUtils.NotImplemented(Id, "== Equals(Entity)");
+    public override bool    Equals(object obj) {
+        if (obj is Entity other) {
+            return rawEntity == other.rawEntity && store == other.store;
+        }
+        return false;
+    }
+    // was: public override bool    Equals(object obj)  => throw EntityUtils.NotImplemented(Id, "== Equals(Entity)");
 
-    /// <summary> Note: Not implemented to avoid excessive boxing. </summary>
-    /// <remarks> Use <see cref="Id"/> or <see cref="EntityUtils.EqualityComparer"/> </remarks>
-    public override int     GetHashCode()       => throw EntityUtils.NotImplemented(Id, nameof(Id));
+    public override int     GetHashCode()       => Id ^ Revision;
+    // was: public override int     GetHashCode()       => throw EntityUtils.NotImplemented(Id, nameof(Id));
 
     public override string  ToString()          => EntityUtils.EntityToString(this);
 

diff --git a/src/ECS/Entity/EntityUtils.cs b/src/ECS/Entity/EntityUtils.cs
@@ -70,10 +70,10 @@ internal static int ComponentCount (this Entity entity) {
         return type.componentCount + entity.Scripts.Length;
     }
 
-    internal static Exception NotImplemented(int id, string use) {
+    /* internal static Exception NotImplemented(int id, string use) {
         var msg = $"to avoid excessive boxing. Use {use} or {nameof(EntityUtils)}.{nameof(EqualityComparer)}. id: {id}";
         return new NotImplementedException(msg);
-    }
+    } */
 
     internal static string EntityToString(Entity entity) {
         if (entity.store == null) {

diff --git a/src/Tests/ECS/Entity/Test_Entity.cs b/src/Tests/ECS/Entity/Test_Entity.cs
@@ -342,6 +342,8 @@ public static void Test_Entity_Equality()
         var store       = new EntityStore(PidType.RandomPids);
         var entity1     = store.CreateEntity(1);
         var entity2     = store.CreateEntity(2);
+        var entity1obj  = (object)entity1;
+        var entity2obj  = (object)entity2;
 
         // --- operator ==, !=
         IsFalse (entity1 == entity2);
@@ -356,22 +358,59 @@ public static void Test_Entity_Equality()
         var start = Mem.GetAllocatedBytes();
         Mem.AreEqual (false, entity1.Equals(entity2));
         Mem.AreEqual (true,  entity1.Equals(entity1));
-        Mem.AssertNoAlloc(start);
 
         // --- object.GetHashCode()
-        var e = Throws<NotImplementedException>(() => {
-            _ = entity1.GetHashCode();
-        });
-        AreEqual("to avoid excessive boxing. Use Id or EntityUtils.EqualityComparer. id: 1", e!.Message);
+        Mem.AreEqual(1, entity1.GetHashCode());
 
         // --- object.Equals()
-        e = Throws<NotImplementedException>(() => {
-            object obj = entity1;
-            _ = obj.Equals(entity2);
-        });
-        AreEqual("to avoid excessive boxing. Use == Equals(Entity) or EntityUtils.EqualityComparer. id: 1", e!.Message);
+        Mem.IsFalse(entity1.Equals(null));
+        Mem.IsTrue (entity1.Equals(entity1obj));
+        Mem.IsFalse(entity1.Equals(entity2obj));
+        Mem.AssertNoAlloc(start);
+    }
+
+    [Test]
+    public static void Test_Entity_Dictionary_object()
+    {
+        var store = new EntityStore();
+        var map = new Dictionary<object, int>();
+        map.EnsureCapacity(10);
+        var entity1 = store.CreateEntity(1);
+        var entity2 = store.CreateEntity(2);
+        var entity3 = store.CreateEntity(3);
+        // all subsequent statements cause boxing
+        map.Add(entity1, 1);
+        map.Add(entity2, 2);
+        map.Add(entity3, 3);
+        Mem.AreEqual (2, map[entity2]);
+        Mem.IsTrue(map.ContainsKey(entity2));
+        Mem.IsTrue(map.TryGetValue(entity2, out _));
     }
 
+    [Test]
+    public static void Test_Entity_Dictionary_generic()
+    {
+        var store = new EntityStore();
+        var map = new Dictionary<Entity, int>();
+        map.EnsureCapacity(10);
+        var entity1 = store.CreateEntity(1);
+        var entity2 = store.CreateEntity(2);
+        var entity3 = store.CreateEntity(3);
+        map.Add(entity1, 1);                    // force one time allocation
+        _ = map[entity1];                       // force one time allocation
+        _ = map.ContainsKey(entity1);           // force one time allocation
+        _ = map.TryGetValue(entity1, out _);    // force one time allocation
+
+        var start = Mem.GetAllocatedBytes();    // force one time allocation
+        map.Add(entity2, 2);
+        map.Add(entity3, 3);
+        Mem.AreEqual (2, map[entity2]);
+        Mem.IsTrue(map.ContainsKey(entity2));
+        Mem.IsTrue(map.TryGetValue(entity2, out _));
+        Mem.AssertNoAlloc(start);
+    }
+
+
     [Test]
     public static void Test_Entity_Enabled()
     {