Allows multiple calls to TaskAsyncEnumerable.Enumerator.Dispose without raising exception.

Author: CXuesong

AsyncEnumerableExtensions/AsyncEnumerableExtensions.csproj

@@ -4,7 +4,7 @@
     <TargetFramework>netstandard1.1</TargetFramework>
     <PackageId>CXuesong.AsyncEnumerableExtensions</PackageId>
     <Authors>CXuesong</Authors>
-    <Version>0.1.2</Version>
+    <Version>0.1.3</Version>
     <Description>Some rudimentary utilities to flavor Ix.Async. Such as asynchronous generator methods.</Description>
     <RepositoryUrl>https://github.com/CXuesong/AsyncEnumerableExtensions</RepositoryUrl>
     <RepositoryType>git</RepositoryType>

AsyncEnumerableExtensions/TaskAsyncEnumerable.cs

@@ -37,7 +37,6 @@ private class Enumerator : IAsyncEnumerator<T>
         {
 
             private readonly Func<IAsyncEnumerableSink<T>, CancellationToken, Task> generator;
-            private readonly bool acceptsCancellationToken;
             private Task generatorTask;
             private AsyncEnumerableBuffer<T> buffer;
             private CancellationTokenSource taskCompletionTokenSource;
@@ -48,12 +47,12 @@ public Enumerator(Func<IAsyncEnumerableSink<T>, CancellationToken, Task> generat
             {
                 Debug.Assert(generator != null);
                 this.generator = generator;
-                this.acceptsCancellationToken = acceptsCancellationToken;
             }
 
             /// <inheritdoc />
             public void Dispose()
             {
+                if (generatorTask == null) return;
                 // Notify the cancellation.
                 if (lastCombinedCancellationTokenSource != taskCompletionTokenSource)
                     lastCombinedCancellationTokenSource.Dispose();