Added support for interfaces in GetObservable<>() as well as deep

inheritence. Previous implementation only supported the requested concrete
type and the immediate base type.

Source/Tx.Core/Demultiplexor.cs

@@ -16,6 +16,8 @@ namespace System.Reactive
     {
         private readonly Dictionary<Type, IObserver<object>> _outputs = new Dictionary<Type, IObserver<object>>();
 
+        private readonly Dictionary<Type, List<Type>> _knownOutputMappings = new Dictionary<Type, List<Type>>();
+
         public void OnCompleted()
         {
             foreach (var output in _outputs.Values.ToArray())
@@ -32,17 +34,22 @@ namespace System.Reactive
             }
         }
 
-        public void OnNext(object value)
+        public void OnNext(object inputObject)
         {
-            IObserver<object> output;
-            if (_outputs.TryGetValue(value.GetType(), out output))
+            var inputObjectType = inputObject.GetType();
+
+            if (!_knownOutputMappings.ContainsKey(inputObjectType))
             {
-                output.OnNext(value);
+                _knownOutputMappings.Add(inputObjectType, new List<Type>());
+                foreach (var type in GetTypes(inputObjectType).Where(type => _outputs.ContainsKey(type)))
+                {
+                    _knownOutputMappings[inputObjectType].Add(type);
+                }
             }
 
-            if (_outputs.TryGetValue(value.GetType().BaseType, out output))
+            foreach (var keyType in _knownOutputMappings[inputObjectType])
             {
-                output.OnNext(value);
+                _outputs[keyType].OnNext(inputObject);
             }
         }
 
@@ -54,16 +61,41 @@ namespace System.Reactive
         public IObservable<TOutput> GetObservable<TOutput>()
         {
             IObserver<object> o;
-            if (!_outputs.TryGetValue(typeof (TOutput), out o))
+            if (!_outputs.TryGetValue(typeof(TOutput), out o))
             {
                 o = new OutputSubject<TOutput>();
-                _outputs.Add(typeof (TOutput), o);
+                _outputs.Add(typeof(TOutput), o);
+                RefreshKnownOutputMappings(typeof(TOutput));
             }
 
-            var output = (IObservable<TOutput>) o;
+            var output = (IObservable<TOutput>)o;
             return output;
         }
 
+        private List<Type> GetTypes(Type inputType)
+        {
+            var typeList = new List<Type>();
+            var temp = inputType;
+            while (temp.FullName != typeof(object).FullName)
+            {
+                typeList.Add(temp);
+                temp = temp.BaseType;
+            }
+            typeList.AddRange(inputType.GetInterfaces());
+            return typeList;
+        }
+
+        private void RefreshKnownOutputMappings(Type outputType)
+        {
+            foreach (var knownMappings in _knownOutputMappings)
+            {
+                if (GetTypes(knownMappings.Key).Contains(outputType) && !knownMappings.Value.Contains(outputType))
+                {
+                    knownMappings.Value.Add(outputType);
+                }
+            }
+        }
+
         private class OutputSubject<T> : ISubject<object, T>, IDisposable
         {
             private readonly Subject<T> _subject;
@@ -95,7 +127,7 @@ namespace System.Reactive
 
             public void OnNext(object value)
             {
-                _subject.OnNext((T) value);
+                _subject.OnNext((T)value);
             }
 
             public IDisposable Subscribe(IObserver<T> observer)

Test/UnitTests/DemultiplexorTest.cs

@@ -29,6 +29,82 @@ namespace Tests.Tx
             Assert.AreEqual(2, stringObserver.Count);
         }
 
+        [TestMethod]
+        public void GetObservableInheritenceTest1()
+        {
+            var itemA = new TestClassA();
+            var itemB = new TestClassB();
+            var itemC = new TestClassC();
+            var interfaceObserver = new CountObserver<ITestClassA>();
+            var itemAObserver = new CountObserver<TestClassA>();
+            var itemBObserver = new CountObserver<TestClassB>();
+            var itemCObserver = new CountObserver<TestClassC>();
+            
+            var demux = new Demultiplexor();
+
+            demux.GetObservable<ITestClassA>().Subscribe(interfaceObserver);
+            demux.GetObservable<TestClassA>().Subscribe(itemAObserver);
+            demux.GetObservable<TestClassB>().Subscribe(itemBObserver);
+            demux.GetObservable<TestClassC>().Subscribe(itemCObserver);
+
+            demux.OnNext(itemA);
+            demux.OnNext(itemB);
+            demux.OnNext(itemC);
+
+            Assert.AreEqual(3, interfaceObserver.Count);
+            Assert.AreEqual(3, itemAObserver.Count);
+            Assert.AreEqual(2, itemBObserver.Count);
+            Assert.AreEqual(1, itemCObserver.Count);
+        }
+
+        [TestMethod]
+        public void TestLateGetObservableRefreshesCache()
+        {
+            var itemA = new TestClassA();
+            var itemB = new TestClassB();
+            var itemC = new TestClassC();
+            var interfaceObserver = new CountObserver<ITestClassA>();
+            var itemAObserver = new CountObserver<TestClassA>();
+            var itemBObserver = new CountObserver<TestClassB>();
+            var itemCObserver = new CountObserver<TestClassC>();
+
+            var demux = new Demultiplexor();
+
+            demux.GetObservable<TestClassA>().Subscribe(itemAObserver);
+            demux.GetObservable<TestClassB>().Subscribe(itemBObserver);
+            demux.GetObservable<TestClassC>().Subscribe(itemCObserver);
+
+            demux.OnNext(itemA);
+            demux.GetObservable<ITestClassA>().Subscribe(interfaceObserver);
+            demux.OnNext(itemB);
+            demux.OnNext(itemC);
+
+            Assert.AreEqual(2, interfaceObserver.Count);
+            Assert.AreEqual(3, itemAObserver.Count);
+            Assert.AreEqual(2, itemBObserver.Count);
+            Assert.AreEqual(1, itemCObserver.Count);
+        }
+
+        interface ITestClassA
+        {
+            int ValueA { get; set; }   
+        }
+
+        class TestClassA : ITestClassA
+        {
+            public int ValueA { get; set; }
+        }
+
+        class TestClassB : TestClassA
+        {
+            public string ValueB { get; set; }
+        }
+
+        class TestClassC : TestClassB
+        {
+            public double ValueC { get; set; }
+        }
+
         class CountObserver<T> : IObserver<T>
         {
             int _count;