introduce ReactiveExtensions to make working with IObservable<T> easier

src/AddIns/Misc/SearchAndReplace/Project/Engine/SearchManager.cs

@@ -134,7 +134,7 @@ namespace SearchAndReplace
 					delegate {
 						var list = fileList.ToList();
 						this.count = list.Count;
-						Parallel.ForEach(fileList, new ParallelOptions { CancellationToken = monitor.CancellationToken, MaxDegreeOfParallelism = Environment.ProcessorCount }, fileName => SearchFile(fileName, strategy, monitor.CancellationToken));
+						Parallel.ForEach(list, new ParallelOptions { CancellationToken = monitor.CancellationToken, MaxDegreeOfParallelism = Environment.ProcessorCount }, fileName => SearchFile(fileName, strategy, monitor.CancellationToken));
 					});
 				task.ContinueWith(t => { if (t.Exception != null) observer.OnError(t.Exception); else observer.OnCompleted(); this.Dispose(); });
 				task.Start();
@@ -363,8 +363,13 @@ namespace SearchAndReplace
 		
 		public static void MarkAll(IObservable<SearchResultMatch> results)
 		{
-			var marker = new SearchResultMarker();
-			marker.Registration = results.Subscribe(marker);
+			int count = 0;
+			results.ObserveOnUIThread()
+				.Subscribe(
+					match => { count++; MarkResult(match, false); },
+					error => MessageService.ShowException(error),
+					() => ShowMarkDoneMessage(count)
+				);
 		}
 		
 		static void MarkResult(SearchResultMatch result, bool switchToOpenedView = true)
@@ -416,41 +421,6 @@ namespace SearchAndReplace
 			MessageService.ShowMessage("${res:Dialog.NewProject.SearchReplace.SearchStringNotFound}", "${res:Dialog.NewProject.SearchReplace.SearchStringNotFound.Title}");
 		}
 		
-		class SearchResultMarker : IObserver<SearchResultMatch>
-		{
-			public IDisposable Registration { get; set; }
-			
-			int count;
-			
-			void IObserver<SearchResultMatch>.OnNext(SearchResultMatch value)
-			{
-				Interlocked.Increment(ref count);
-				WorkbenchSingleton.SafeThreadAsyncCall((Action)delegate { MarkResult(value, false); });
-			}
-			
-			void IObserver<SearchResultMatch>.OnError(Exception error)
-			{
-				MessageService.ShowException(error);
-				OnCompleted(false);
-			}
-			
-			void OnCompleted(bool success)
-			{
-				WorkbenchSingleton.SafeThreadCall(
-					(Action)delegate {
-						if (Registration != null)
-							Registration.Dispose();
-						if (success)
-							ShowMarkDoneMessage(count);
-					});
-			}
-			
-			void IObserver<SearchResultMatch>.OnCompleted()
-			{
-				OnCompleted(true);
-			}
-		}
-		
 		public static void SelectResult(SearchResultMatch result)
 		{
 			if (result == null) {

src/AddIns/Misc/SearchAndReplace/Project/Gui/DefaultSearchResult.cs

@@ -123,7 +123,7 @@ namespace SearchAndReplace
 		public ISearchResult CreateSearchResult(string title, IObservable<SearchResultMatch> matches)
 		{
 			var osr = new ObserverSearchResult(title);
-			osr.Registration = matches.Subscribe(osr);
+			osr.Registration = matches.ObserveOnUIThread().Subscribe(osr);
 			return osr;
 		}
 	}
@@ -223,7 +223,7 @@ namespace SearchAndReplace
 		
 		void IObserver<SearchResultMatch>.OnNext(SearchResultMatch value)
 		{
-			WorkbenchSingleton.SafeThreadCall((Action)delegate { rootNode.Add(value); });
+			rootNode.Add(value);
 		}
 		
 		void IObserver<SearchResultMatch>.OnError(Exception error)
@@ -234,12 +234,9 @@ namespace SearchAndReplace
 		
 		void OnCompleted()
 		{
-			WorkbenchSingleton.SafeThreadCall(
-				(Action)delegate {
-					stopButton.Visibility = Visibility.Collapsed;
-					if (Registration != null)
-						Registration.Dispose();
-				});
+			stopButton.Visibility = Visibility.Collapsed;
+			if (Registration != null)
+				Registration.Dispose();
 		}
 		
 		void IObserver<SearchResultMatch>.OnCompleted()

src/Main/Base/Project/ICSharpCode.SharpDevelop.csproj

@@ -740,6 +740,7 @@
     <Compile Include="Src\Services\ProjectService\ProjectLoader.cs" />
     <Compile Include="Src\Services\WebProjectService\WebProjectService.cs" />
     <Compile Include="Src\Util\FakeXmlViewContent.cs" />
+    <Compile Include="Src\Util\ReactiveExtensions.cs" />
     <Compile Include="Src\Util\TreeNode.cs" />
     <Compile Include="Src\Util\NativeMethods.cs" />
     <Compile Include="Src\Util\ProcessRunnerException.cs" />

src/Main/Base/Project/Src/Util/ReactiveExtensions.cs

@@ -0,0 +1,83 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Windows.Threading;
+using ICSharpCode.SharpDevelop.Gui;
+
+namespace ICSharpCode.SharpDevelop
+{
+	/// <summary>
+	/// Provides extension methods for IObservable&lt;T&gt;.
+	/// </summary>
+	public static class ReactiveExtensions
+	{
+		public static IObservable<T> ObserveOnUIThread<T>(this IObservable<T> source)
+		{
+			return new AnonymousObservable<T>(
+				observer => source.Subscribe(
+					new AnonymousObserver<T>(
+						value => WorkbenchSingleton.SafeThreadAsyncCall(delegate { observer.OnNext(value); }),
+						exception => WorkbenchSingleton.SafeThreadAsyncCall(delegate { observer.OnError(exception); }),
+						() => WorkbenchSingleton.SafeThreadAsyncCall(delegate { observer.OnCompleted(); })
+					)
+				)
+			);
+		}
+		
+		public static IDisposable Subscribe<T>(this IObservable<T> source, Action<T> onNext, Action<Exception> onError, Action onCompleted)
+		{
+			return source.Subscribe(new AnonymousObserver<T>(onNext, onError, onCompleted));
+		}
+		
+		class AnonymousObservable<T> : IObservable<T>
+		{
+			Func<IObserver<T>, IDisposable> subscribe;
+			
+			public AnonymousObservable(Func<IObserver<T>, IDisposable> subscribe)
+			{
+				this.subscribe = subscribe;
+			}
+			
+			public IDisposable Subscribe(IObserver<T> observer)
+			{
+				return subscribe(observer);
+			}
+		}
+		
+		class AnonymousObserver<T> : IObserver<T>
+		{
+			Action<T> onNext;
+			Action<Exception> onError;
+			Action onCompleted;
+			
+			public AnonymousObserver(Action<T> onNext, Action<Exception> onError, Action onCompleted)
+			{
+				if (onNext == null)
+					throw new ArgumentNullException("onNext");
+				if (onError == null)
+					throw new ArgumentNullException("onError");
+				if (onCompleted == null)
+					throw new ArgumentNullException("onCompleted");
+				this.onNext = onNext;
+				this.onError = onError;
+				this.onCompleted = onCompleted;
+			}
+			
+			public void OnNext(T value)
+			{
+				onNext(value);
+			}
+			
+			public void OnError(Exception error)
+			{
+				onError(error);
+			}
+			
+			public void OnCompleted()
+			{
+				onCompleted();
+			}
+		}
+	}
+}