Adding FromAsync.

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/FromAsync.cs

@@ -0,0 +1,85 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+using System.Reactive.Concurrency;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace System.Reactive.Linq
+{
+    partial class AsyncObservable
+    {
+        public static IAsyncObservable<TResult> FromAsync<TResult>(Func<Task<TResult>> functionAsync)
+        {
+            if (functionAsync == null)
+                throw new ArgumentNullException(nameof(functionAsync));
+
+            return Defer(() => StartAsync(functionAsync));
+        }
+
+        public static IAsyncObservable<TResult> FromAsync<TResult>(Func<Task<TResult>> functionAsync, IAsyncScheduler scheduler)
+        {
+            if (functionAsync == null)
+                throw new ArgumentNullException(nameof(functionAsync));
+            if (scheduler == null)
+                throw new ArgumentNullException(nameof(scheduler));
+
+            return Defer(() => StartAsync(functionAsync, scheduler));
+        }
+
+        public static IAsyncObservable<TResult> FromAsync<TResult>(Func<CancellationToken, Task<TResult>> functionAsync)
+        {
+            if (functionAsync == null)
+                throw new ArgumentNullException(nameof(functionAsync));
+
+            return Defer(() => StartAsync(functionAsync));
+        }
+
+        public static IAsyncObservable<TResult> FromAsync<TResult>(Func<CancellationToken, Task<TResult>> functionAsync, IAsyncScheduler scheduler)
+        {
+            if (functionAsync == null)
+                throw new ArgumentNullException(nameof(functionAsync));
+            if (scheduler == null)
+                throw new ArgumentNullException(nameof(scheduler));
+
+            return Defer(() => StartAsync(functionAsync, scheduler));
+        }
+
+        public static IAsyncObservable<Unit> FromAsync(Func<Task> actionAsync)
+        {
+            if (actionAsync == null)
+                throw new ArgumentNullException(nameof(actionAsync));
+
+            return Defer(() => StartAsync(actionAsync));
+        }
+
+        public static IAsyncObservable<Unit> FromAsync(Func<Task> actionAsync, IAsyncScheduler scheduler)
+        {
+            if (actionAsync == null)
+                throw new ArgumentNullException(nameof(actionAsync));
+            if (scheduler == null)
+                throw new ArgumentNullException(nameof(scheduler));
+
+            return Defer(() => StartAsync(actionAsync, scheduler));
+        }
+
+        public static IAsyncObservable<Unit> FromAsync(Func<CancellationToken, Task> actionAsync)
+        {
+            if (actionAsync == null)
+                throw new ArgumentNullException(nameof(actionAsync));
+
+            return Defer(() => StartAsync(actionAsync));
+        }
+
+        public static IAsyncObservable<Unit> FromAsync(Func<CancellationToken, Task> actionAsync, IAsyncScheduler scheduler)
+        {
+            if (actionAsync == null)
+                throw new ArgumentNullException(nameof(actionAsync));
+            if (scheduler == null)
+                throw new ArgumentNullException(nameof(scheduler));
+
+            return Defer(() => StartAsync(actionAsync, scheduler));
+        }
+    }
+}