1 files changed, 124 insertions, 0 deletions

diff --git a/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/Count.cs b/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/Count.cs
new file mode 100644
index 0000000..7432816
--- /dev/null
+++ b/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/Count.cs
@@ -0,0 +1,124 @@
+// 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 Count<TSource> : Producer<int>
+    {
+        private readonly IObservable<TSource> _source;
+        private readonly Func<TSource, bool> _predicate;
+
+        public Count(IObservable<TSource> source)
+        {
+            _source = source;
+        }
+
+        public Count(IObservable<TSource> source, Func<TSource, bool> predicate)
+        {
+            _source = source;
+            _predicate = predicate;
+        }
+
+        protected override IDisposable Run(IObserver<int> observer, IDisposable cancel, Action<IDisposable> setSink)
+        {
+            if (_predicate == null)
+            {
+                var sink = new _(observer, cancel);
+                setSink(sink);
+                return _source.SubscribeSafe(sink);
+            }
+            else
+            {
+                var sink = new π(this, observer, cancel);
+                setSink(sink);
+                return _source.SubscribeSafe(sink);
+            }
+        }
+
+        class _ : Sink<int>, IObserver<TSource>
+        {
+            private int _count;
+
+            public _(IObserver<int> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _count = 0;
+            }
+
+            public void OnNext(TSource value)
+            {
+                try
+                {
+                    checked
+                    {
+                        _count++;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    base._observer.OnError(ex);
+                    base.Dispose();
+                }
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                base._observer.OnNext(_count);
+                base._observer.OnCompleted();
+                base.Dispose();
+            }
+        }
+
+        class π : Sink<int>, IObserver<TSource>
+        {
+            private readonly Count<TSource> _parent;
+            private int _count;
+
+            public π(Count<TSource> parent, IObserver<int> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _parent = parent;
+                _count = 0;
+            }
+
+            public void OnNext(TSource value)
+            {
+                try
+                {
+                    checked
+                    {
+                        if (_parent._predicate(value))
+                            _count++;
+                    }
+                }
+                catch (Exception ex)
+                {
+                    base._observer.OnError(ex);
+                    base.Dispose();
+                }
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                base._observer.OnNext(_count);
+                base._observer.OnCompleted();
+                base.Dispose();
+            }
+        }
+    }
+}
+#endif
\ No newline at end of file