From 7d070d68c9e9bb535a9c4407f1f2d9ce73d15ac9 Mon Sep 17 00:00:00 2001
From: BeanCheeseBurrito <mrbeancheeseburrito@protonmail.com>
Date: Fri, 15 Nov 2024 01:05:46 -0800
Subject: [PATCH] Add ObserverBuilder.ObserverFlags()

---
 src/Flecs.NET.Tests/Cpp/ObserverTests.cs | 99 ++++++++++++++++++++++++
 src/Flecs.NET/Core/ObserverBuilder.cs    | 11 +++
 2 files changed, 110 insertions(+)

diff --git a/src/Flecs.NET.Tests/Cpp/ObserverTests.cs b/src/Flecs.NET.Tests/Cpp/ObserverTests.cs
index 75d78d2e..a115a988 100644
--- a/src/Flecs.NET.Tests/Cpp/ObserverTests.cs
+++ b/src/Flecs.NET.Tests/Cpp/ObserverTests.cs
@@ -450,6 +450,105 @@ private void YieldExisting2Terms()
         Assert.Equal(6, count);
     }
 
+    [Fact]
+    private void YieldExistingOnCreateFlag()
+    {
+        using World world = World.Create();
+
+        Entity e1 = world.Entity().Add<Tag0>();
+        Entity e2 = world.Entity().Add<Tag0>();
+        Entity e3 = world.Entity().Add<Tag0>().Add<Tag1>();
+
+        int count = 0;
+
+        Observer o = world.Observer()
+            .With<Tag0>()
+            .Event(Ecs.OnAdd)
+            .Event(Ecs.OnRemove)
+            .ObserverFlags(EcsObserverYieldOnCreate)
+            .Each((Entity e) =>
+            {
+                if (e == e1)
+                    count++;
+                if (e == e2)
+                    count += 2;
+                if (e == e3)
+                    count += 3;
+            });
+
+        Assert.Equal(6, count);
+
+        o.Destruct();
+
+        Assert.Equal(6, count);
+    }
+
+    [Fact]
+    private void YieldExistingOnDeleteFlag()
+    {
+        using World world = World.Create();
+
+        Entity e1 = world.Entity().Add<Tag0>();
+        Entity e2 = world.Entity().Add<Tag0>();
+        Entity e3 = world.Entity().Add<Tag0>().Add<Tag1>();
+
+        int count = 0;
+
+        Observer o = world.Observer()
+            .With<Tag0>()
+            .Event(Ecs.OnAdd)
+            .Event(Ecs.OnRemove)
+            .ObserverFlags(EcsObserverYieldOnDelete)
+            .Each((Entity e) =>
+            {
+                if (e == e1)
+                    count++;
+                if (e == e2)
+                    count += 2;
+                if (e == e3)
+                    count += 3;
+            });
+
+        Assert.Equal(0, count);
+
+        o.Destruct();
+
+        Assert.Equal(6, count);
+    }
+
+    [Fact]
+    private void YieldExistingOnCreateDeleteFlag()
+    {
+        using World world = World.Create();
+
+        Entity e1 = world.Entity().Add<Tag0>();
+        Entity e2 = world.Entity().Add<Tag0>();
+        Entity e3 = world.Entity().Add<Tag0>().Add<Tag1>();
+
+        int count = 0;
+
+        Observer o = world.Observer()
+            .With<Tag0>()
+            .Event(Ecs.OnAdd)
+            .Event(Ecs.OnRemove)
+            .ObserverFlags(EcsObserverYieldOnCreate | EcsObserverYieldOnDelete)
+            .Each((Entity e) =>
+            {
+                if (e == e1)
+                    count++;
+                if (e == e2)
+                    count += 2;
+                if (e == e3)
+                    count += 3;
+            });
+
+        Assert.Equal(6, count);
+
+        o.Destruct();
+
+        Assert.Equal(12, count);
+    }
+
     [Fact]
     private void DefaultCtor()
     {
diff --git a/src/Flecs.NET/Core/ObserverBuilder.cs b/src/Flecs.NET/Core/ObserverBuilder.cs
index b30ad94a..fa993795 100644
--- a/src/Flecs.NET/Core/ObserverBuilder.cs
+++ b/src/Flecs.NET/Core/ObserverBuilder.cs
@@ -105,6 +105,17 @@ public ref ObserverBuilder YieldExisting(bool value = true)
         return ref this;
     }
 
+    /// <summary>
+    ///     Set observer flags.
+    /// </summary>
+    /// <param name="flags">The flags value.</param>
+    /// <returns></returns>
+    public ref ObserverBuilder ObserverFlags(uint flags)
+    {
+        Desc.flags_ |= flags;
+        return ref this;
+    }
+
     /// <summary>
     ///     Set observer context.
     /// </summary>