React to API feedback on VisualStudioRazorParser.

- Changed `ReparseAsync` to be `QueueReparse`. It's now async void to not give the misconception that it blocks until a reparse has been completed.
- Removed `IContextChangedListener`. People can get the same effect of the interface by retrieving the document tracker interface via the `RazorEditorFactoryService` and then when its context changes getting the parser.
- Exposed `TryGetParser` to aid in replacing `IContextChangedListener`.
- Updated tests to not rely on `IContextChangedListener`.

src/Microsoft.VisualStudio.Editor.Razor/DefaultVisualStudioRazorParser.cs

@@ -30,7 +30,6 @@ namespace Microsoft.VisualStudio.Editor.Razor
 
         private readonly object IdleLock = new object();
         private readonly ICompletionBroker _completionBroker;
-        private readonly IEnumerable<IContextChangedListener> _contextChangedListeners;
         private readonly VisualStudioDocumentTracker _documentTracker;
         private readonly ForegroundDispatcher _dispatcher;
         private readonly RazorTemplateEngineFactoryService _templateEngineFactory;
@@ -51,8 +50,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
             VisualStudioDocumentTracker documentTracker,
             RazorTemplateEngineFactoryService templateEngineFactory,
             ErrorReporter errorReporter,
-            ICompletionBroker completionBroker,
+            ICompletionBroker completionBroker)
-            IEnumerable<IContextChangedListener> contextChangedListeners)
         {
             if (dispatcher == null)
             {
@@ -79,16 +77,10 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 throw new ArgumentNullException(nameof(completionBroker));
             }
 
-            if (contextChangedListeners == null)
-            {
-                throw new ArgumentNullException(nameof(contextChangedListeners));
-            }
-
             _dispatcher = dispatcher;
             _templateEngineFactory = templateEngineFactory;
             _errorReporter = errorReporter;
             _completionBroker = completionBroker;
-            _contextChangedListeners = contextChangedListeners;
             _documentTracker = documentTracker;
 
             _documentTracker.ContextChanged += DocumentTracker_ContextChanged;
@@ -110,7 +102,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
         // Used in unit tests to ensure we can block background idle work.
         internal ManualResetEventSlim BlockBackgroundIdleWork { get; set; }
 
-        public override async Task ReparseAsync()
+        public override void QueueReparse()
         {
             // Can be called from any thread
 
@@ -120,7 +112,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
             }
             else
             {
-                await Task.Factory.StartNew(ReparseOnForeground, null, CancellationToken.None, TaskCreationOptions.None, _dispatcher.ForegroundScheduler);
+                Task.Factory.StartNew(ReparseOnForeground, null, CancellationToken.None, TaskCreationOptions.None, _dispatcher.ForegroundScheduler);
             }
         }
 
@@ -145,11 +137,9 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 return;
             }
 
-            NotifyParserContextChanged();
-
             // We have a new parser, force a reparse to generate new document information. Note that this
             // only blocks until the reparse change has been queued.
-            ReparseAsync().GetAwaiter().GetResult();
+            QueueReparse();
         }
 
         // Internal for testing
@@ -171,21 +161,6 @@ namespace Microsoft.VisualStudio.Editor.Razor
             return true;
         }
 
-        // Internal for testing
-        internal void NotifyParserContextChanged()
-        {
-            _dispatcher.AssertForegroundThread();
-
-            // This is temporary until we own the TagHelper resolution system. At that point the parser will push out updates
-            // via DocumentStructureChangedEvents when contexts change. For now, listeners need to know more information about
-            // the parser. In the case that the tracker does not belong to a supported project the editor will tear down its
-            // attachment to the parser when it recognizes the document closing.
-            foreach (var contextChangeListener in _contextChangedListeners)
-            {
-                contextChangeListener.OnContextChanged(this);
-            }
-        }
-
         // Internal for testing
         internal void StartParser()
         {
@@ -303,8 +278,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 }
             }
 
-            // This only blocks until the reparse change has been queued.
+            QueueReparse();
-            ReparseAsync().GetAwaiter().GetResult();
         }
 
         private void ReparseOnForeground(object state)

src/Microsoft.VisualStudio.Editor.Razor/IContextChangedListener.cs

@@ -1,13 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-namespace Microsoft.VisualStudio.Editor.Razor
-{
-    /// <summary>
-    /// This class will cease to be useful once the Razor tooling owns TagHelper discovery
-    /// </summary>
-    public interface IContextChangedListener
-    {
-        void OnContextChanged(VisualStudioRazorParser parser);
-    }
-}

src/Microsoft.VisualStudio.Editor.Razor/RazorEditorFactoryService.cs

@@ -9,7 +9,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
     {
         public abstract bool TryGetDocumentTracker(ITextBuffer textBuffer, out VisualStudioDocumentTracker documentTracker);
 
-        internal abstract bool TryGetParser(ITextBuffer textBuffer, out VisualStudioRazorParser parser);
+        public abstract bool TryGetParser(ITextBuffer textBuffer, out VisualStudioRazorParser parser);
 
         internal abstract bool TryGetSmartIndenter(ITextBuffer textBuffer, out BraceSmartIndenter braceSmartIndenter);
     }

src/Microsoft.VisualStudio.Editor.Razor/VisualStudioRazorParser.cs

@@ -2,7 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.VisualStudio.Text;
 
@@ -22,6 +21,6 @@ namespace Microsoft.VisualStudio.Editor.Razor
 
         public abstract ITextBuffer TextBuffer { get; }
 
-        public abstract Task ReparseAsync();
+        public abstract void QueueReparse();
     }
 }

src/Microsoft.VisualStudio.LanguageServices.Razor/Editor/DefaultRazorEditorFactoryService.cs

@@ -69,7 +69,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor.Editor
             return true;
         }
 
-        internal override bool TryGetParser(ITextBuffer textBuffer, out VisualStudioRazorParser parser)
+        public override bool TryGetParser(ITextBuffer textBuffer, out VisualStudioRazorParser parser)
         {
             if (textBuffer == null)
             {

src/Microsoft.VisualStudio.LanguageServices.Razor/Editor/DefaultVisualStudioRazorParserFactory.cs

@@ -19,13 +19,11 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor.Editor
         private readonly ForegroundDispatcher _dispatcher;
         private readonly TemplateEngineFactoryService _templateEngineFactoryService;
         private readonly ICompletionBroker _completionBroker;
-        private readonly IEnumerable<IContextChangedListener> _parserContextChangedListeners;
         private readonly ErrorReporter _errorReporter;
 
         [ImportingConstructor]
         public DefaultVisualStudioRazorParserFactory(
             ICompletionBroker completionBroker,
-            [ImportMany(typeof(IContextChangedListener))] IEnumerable<IContextChangedListener> parserContextChangedListeners,
             [Import(typeof(VisualStudioWorkspace))] Workspace workspace)
         {
             if (completionBroker == null)
@@ -33,18 +31,12 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor.Editor
                 throw new ArgumentNullException(nameof(completionBroker));
             }
 
-            if (parserContextChangedListeners == null)
-            {
-                throw new ArgumentNullException(nameof(parserContextChangedListeners));
-            }
-
             if (workspace == null)
             {
                 throw new ArgumentNullException(nameof(workspace));
             }
 
             _completionBroker = completionBroker;
-            _parserContextChangedListeners = parserContextChangedListeners;
             _dispatcher = workspace.Services.GetRequiredService<ForegroundDispatcher>();
             _errorReporter = workspace.Services.GetRequiredService<ErrorReporter>();
             var razorLanguageServices = workspace.Services.GetLanguageServices(RazorLanguage.Name);
@@ -65,8 +57,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Razor.Editor
                 documentTracker,
                 _templateEngineFactoryService,
                 _errorReporter,
-                _completionBroker,
+                _completionBroker);
-                _parserContextChangedListeners);
             return parser;
         }
     }

test/Microsoft.VisualStudio.Editor.Razor.Test/DefaultVisualStudioRazorParserIntegrationTest.cs

@@ -38,8 +38,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 documentTracker,
                 CreateTemplateEngineFactory(),
                 new DefaultErrorReporter(),
-                new TestCompletionBroker(),
+                new TestCompletionBroker()))
-                Enumerable.Empty<IContextChangedListener>()))
             {
                 parser.DocumentTracker_ContextChanged(null, null);
                 var changed = new StringTextSnapshot("Foo @bap Daz");
@@ -528,8 +527,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 documentTracker,
                 templateEngineFactory,
                 new DefaultErrorReporter(),
-                new TestCompletionBroker(),
+                new TestCompletionBroker())
-                Enumerable.Empty<IContextChangedListener>())
             {
                 // We block idle work with the below reset events. Therefore, make tests fast and have the idle timer fire as soon as possible.
                 IdleDelay = TimeSpan.FromMilliseconds(1),

test/Microsoft.VisualStudio.Editor.Razor.Test/DefaultVisualStudioRazorParserTest.cs

@@ -35,8 +35,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 CreateDocumentTracker(),
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>())
-                Enumerable.Empty<IContextChangedListener>())
             {
                 BlockBackgroundIdleWork = new ManualResetEventSlim(),
                 IdleDelay = TimeSpan.FromSeconds(5)
@@ -66,8 +65,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 CreateDocumentTracker(),
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>())
-                Enumerable.Empty<IContextChangedListener>())
             {
                 BlockBackgroundIdleWork = new ManualResetEventSlim(),
                 IdleDelay = TimeSpan.FromSeconds(5)
@@ -96,8 +94,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 CreateDocumentTracker(),
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>()))
-                Enumerable.Empty<IContextChangedListener>()))
             {
                 parser.StartParser();
 
@@ -121,8 +118,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 documentTracker,
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>()))
-                Enumerable.Empty<IContextChangedListener>()))
             {
                 // Act
                 parser.StartParser();
@@ -133,31 +129,6 @@ namespace Microsoft.VisualStudio.Editor.Razor
             }
         }
 
-        [ForegroundFact]
-        public void NotifyParserContextChanged_NotifiesListeners()
-        {
-            // Arrange
-            var listener1 = new Mock<IContextChangedListener>();
-            listener1.Setup(l => l.OnContextChanged(It.IsAny<VisualStudioRazorParser>()));
-            var listener2 = new Mock<IContextChangedListener>();
-            listener2.Setup(l => l.OnContextChanged(It.IsAny<VisualStudioRazorParser>()));
-            using (var parser = new DefaultVisualStudioRazorParser(
-                Dispatcher,
-                CreateDocumentTracker(),
-                Mock.Of<RazorTemplateEngineFactoryService>(),
-                new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
-                new[] { listener1.Object, listener2.Object }))
-            {
-                // Act
-                parser.NotifyParserContextChanged();
-
-                // Assert
-                listener1.Verify();
-                listener2.Verify();
-            }
-        }
-
         [ForegroundFact]
         public void TryReinitializeParser_ReturnsTrue_IfProjectIsSupported()
         {
@@ -167,8 +138,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 CreateDocumentTracker(isSupportedProject: true),
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>()))
-                Enumerable.Empty<IContextChangedListener>()))
             {
                 // Act
                 var result = parser.TryReinitializeParser();
@@ -187,8 +157,7 @@ namespace Microsoft.VisualStudio.Editor.Razor
                 CreateDocumentTracker(isSupportedProject: false),
                 Mock.Of<RazorTemplateEngineFactoryService>(),
                 new DefaultErrorReporter(),
-                Mock.Of<ICompletionBroker>(),
+                Mock.Of<ICompletionBroker>()))
-                Enumerable.Empty<IContextChangedListener>()))
             {
                 // Act
                 var result = parser.TryReinitializeParser();