Empty

src/R3/Factories/Empty.cs

@@ -0,0 +1,71 @@
+namespace R3
+{
+    public static partial class EventFactory
+    {
+        public static CompletableEvent<TMessage, Unit> Empty<TMessage>()
+        {
+            return new Empty<TMessage>();
+        }
+
+        public static CompletableEvent<TMessage, Unit> Empty<TMessage>(TimeProvider timeProvider)
+        {
+            return Empty<TMessage>(TimeSpan.Zero, timeProvider);
+        }
+
+        public static CompletableEvent<TMessage, Unit> Empty<TMessage>(TimeSpan dueTime, TimeProvider timeProvider)
+        {
+            return new EmptyT<TMessage>(dueTime, timeProvider);
+        }
+    }
+}
+
+namespace R3.Factories
+{
+    internal sealed class Empty<TMessage> : CompletableEvent<TMessage, Unit>
+    {
+        protected override IDisposable SubscribeCore(Subscriber<TMessage, Unit> subscriber)
+        {
+            subscriber.OnCompleted(default);
+            return Disposable.Empty;
+        }
+    }
+
+    internal sealed class EmptyT<TMessage>(TimeSpan dueTime, TimeProvider timeProvider) : CompletableEvent<TMessage, Unit>
+    {
+        protected override IDisposable SubscribeCore(Subscriber<TMessage, Unit> subscriber)
+        {
+            var method = new _Empty(subscriber);
+            method.Timer = timeProvider.CreateStoppedTimer(_Empty.timerCallback, method);
+            method.Timer.InvokeOnce(dueTime);
+            return method;
+        }
+
+        sealed class _Empty(Subscriber<TMessage, Unit> subscriber) : IDisposable
+        {
+            public static readonly TimerCallback timerCallback = NextTick;
+
+            readonly Subscriber<TMessage, Unit> subscriber = subscriber;
+
+            public ITimer? Timer { get; set; }
+
+            static void NextTick(object? state)
+            {
+                var self = (_Empty)state!;
+                try
+                {
+                    self.subscriber.OnCompleted();
+                }
+                finally
+                {
+                    self.Dispose();
+                }
+            }
+
+            public void Dispose()
+            {
+                Timer?.Dispose();
+                Timer = null;
+            }
+        }
+    }
+}

src/R3/Factories/_EventFactory.cs

@@ -1,9 +1,9 @@
 namespace R3
 {
-    // TODO: this is working space, will remove this file after complete.
-
     public static partial class EventFactory
     {
+        // TODO: this is working space, will remove this file after complete.
+
         // TODO: Empty, Never, Throw, Defer, DeferAsync, FromAsync, FromAsyncPattern, FromEvent, FromEventPattern, Interval, Range, Repeat, Start, Timer, Using, Create
 
         // TODO: Convert
@@ -20,10 +20,11 @@ public static partial class EventFactory
         // AsObservable
         // AsSingleUnitObservable
         // AsUnitObservable
-
     }
 }
 
 namespace R3.Factories
 {
+
+
 }

src/R3/Operators/Select.cs

@@ -6,6 +6,8 @@ public static partial class EventExtensions
         // TODO: CompletableEvent.Select
         // TODO: Element index overload
 
+        // TODO: Select for TComplete
+
         public static Event<TResult> Select<TMessage, TResult>(this Event<TMessage> source, Func<TMessage, TResult> selector)
         {
             return new Select<TMessage, TResult>(source, selector);

tests/R3.Tests/FactoryTests/EmptyTest.cs

@@ -0,0 +1,26 @@
+using Microsoft.Extensions.Time.Testing;
+
+namespace R3.Tests.FactoryTests;
+
+public class EmptyTest
+{
+    [Fact]
+    public void Empty()
+    {
+        using var list = EventFactory.Empty<int>().LiveRecord();
+        list.AssertIsCompleted();
+    }
+
+    [Fact]
+    public void EmptyWithTime()
+    {
+        var fakeTime = new FakeTimeProvider();
+        using var list = EventFactory.Empty<int>(TimeSpan.FromSeconds(5), fakeTime).LiveRecord();
+
+        fakeTime.Advance(TimeSpan.FromSeconds(4));
+        list.AssertIsNotCompleted();
+
+        fakeTime.Advance(TimeSpan.FromSeconds(1));
+        list.AssertIsCompleted();
+    }
+}

tests/R3.Tests/OperatorTests/ReturnTest.cs → tests/R3.Tests/FactoryTests/ReturnTest.cs

@@ -1,6 +1,6 @@
 using Microsoft.Extensions.Time.Testing;
 
-namespace R3.Tests.OperatorTests;
+namespace R3.Tests.FactoryTests;
 
 public class ReturnTest
 {