1 files changed, 140 insertions, 0 deletions
diff --git a/Rx/NET/Source/System.Reactive.Linq/Reactive/Linq/Observable/LastAsync.cs b/Rx/NET/Source/System.Reactive.Linq/Reactive/Linq/Observable/LastAsync.cs
new file mode 100644
index 0000000..1ecd930
--- /dev/null
+++ b/Rx/NET/Source/System.Reactive.Linq/Reactive/Linq/Observable/LastAsync.cs
@@ -0,0 +1,140 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+#if !NO_PERF
+using System;
+
+namespace System.Reactive.Linq.Observαble
+{
+    class LastAsync<TSource> : Producer<TSource>
+    {
+        private readonly IObservable<TSource> _source;
+        private readonly Func<TSource, bool> _predicate;
+        private readonly bool _throwOnEmpty;
+
+        public LastAsync(IObservable<TSource> source, Func<TSource, bool> predicate, bool throwOnEmpty)
+        {
+            _source = source;
+            _predicate = predicate;
+            _throwOnEmpty = throwOnEmpty;
+        }
+
+        protected override IDisposable Run(IObserver<TSource> observer, IDisposable cancel, Action<IDisposable> setSink)
+        {
+            if (_predicate != null)
+            {
+                var sink = new π(this, observer, cancel);
+                setSink(sink);
+                return _source.SubscribeSafe(sink);
+            }
+            else
+            {
+                var sink = new _(this, observer, cancel);
+                setSink(sink);
+                return _source.SubscribeSafe(sink);
+            }
+        }
+
+        class _ : Sink<TSource>, IObserver<TSource>
+        {
+            private readonly LastAsync<TSource> _parent;
+            private TSource _value;
+            private bool _seenValue;
+
+            public _(LastAsync<TSource> parent, IObserver<TSource> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _parent = parent;
+
+                _value = default(TSource);
+                _seenValue = false;
+            }
+
+            public void OnNext(TSource value)
+            {
+                _value = value;
+                _seenValue = true;
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                if (!_seenValue && _parent._throwOnEmpty)
+                {
+                    base._observer.OnError(new InvalidOperationException(Strings_Linq.NO_ELEMENTS));
+                }
+                else
+                {
+                    base._observer.OnNext(_value);
+                    base._observer.OnCompleted();
+                }
+
+                base.Dispose();
+            }
+        }
+
+        class π : Sink<TSource>, IObserver<TSource>
+        {
+            private readonly LastAsync<TSource> _parent;
+            private TSource _value;
+            private bool _seenValue;
+
+            public π(LastAsync<TSource> parent, IObserver<TSource> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _parent = parent;
+
+                _value = default(TSource);
+                _seenValue = false;
+            }
+
+            public void OnNext(TSource value)
+            {
+                var b = false;
+
+                try
+                {
+                    b = _parent._predicate(value);
+                }
+                catch (Exception ex)
+                {
+                    base._observer.OnError(ex);
+                    base.Dispose();
+                    return;
+                }
+
+                if (b)
+                {
+                    _value = value;
+                    _seenValue = true;
+                }
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                if (!_seenValue && _parent._throwOnEmpty)
+                {
+                    base._observer.OnError(new InvalidOperationException(Strings_Linq.NO_MATCHING_ELEMENTS));
+                }
+                else
+                {
+                    base._observer.OnNext(_value);
+                    base._observer.OnCompleted();
+                }
+
+                base.Dispose();
+            }
+        }
+    }
+}
+#endif
+\ No newline at end of file