Move repeated workspace methods to extension and cleanup command handlers.

src/EditorFeatures/Core.Wpf/InlineRename/CommandHandlers/RenameCommandHandler_RenameHandler.cs

@@ -24,19 +24,9 @@ public VSCommanding.CommandState GetCommandState(RenameCommandArgs args)
                 return VSCommanding.CommandState.Unspecified;
             }
 
-            var textContainer = args.SubjectBuffer.AsTextContainer();
-            if (!Workspace.TryGetWorkspace(textContainer, out var workspace))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            if (!workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRename(args.SubjectBuffer))
+            if (!args.SubjectBuffer.TryGetOwningWorkspace(out var workspace) ||
+                !workspace.CanApplyChange(ApplyChangesKind.ChangeDocument) ||
+                !args.SubjectBuffer.SupportsRename(workspace))
             {
                 return VSCommanding.CommandState.Unspecified;
             }
@@ -56,8 +46,7 @@ public bool ExecuteCommand(RenameCommandArgs args, CommandExecutionContext conte
 
         private void ExecuteRenameWorker(RenameCommandArgs args, CommandExecutionContext context)
         {
-            var snapshot = args.SubjectBuffer.CurrentSnapshot;
-            if (!Workspace.TryGetWorkspace(snapshot.AsText().Container, out var workspace))
+            if (!args.SubjectBuffer.TryGetOwningWorkspace(out var workspace))
             {
                 return;
             }
@@ -87,7 +76,6 @@ private void ExecuteRenameWorker(RenameCommandArgs args, CommandExecutionContext
                 }
             }
 
-            var position = caretPoint.Value;
             var cancellationToken = context.OperationContext.UserCancellationToken;
             var document = args.SubjectBuffer.CurrentSnapshot.GetFullyLoadedOpenDocumentInCurrentContextWithChangesAsync(
                 context.OperationContext).WaitAndGetResult(cancellationToken);

src/EditorFeatures/Core.Wpf/InlineRename/InlineRenameSession.OpenTextBufferManager.cs

@@ -53,13 +53,12 @@ internal class OpenTextBufferManager : ForegroundThreadAffinitizedObject
                 InlineRenameSession session,
                 ITextBuffer subjectBuffer,
                 Workspace workspace,
-                IEnumerable<Document> documents,
                 ITextBufferFactoryService textBufferFactoryService)
                 : base(session.ThreadingContext)
             {
                 _session = session;
                 _subjectBuffer = subjectBuffer;
-                _baseDocuments = documents;
+                _baseDocuments = subjectBuffer.GetRelatedDocuments();
                 _textBufferFactoryService = textBufferFactoryService;
                 _subjectBuffer.ChangedLowPriority += OnTextBufferChanged;
 

src/EditorFeatures/Core.Wpf/InlineRename/InlineRenameSession.cs

@@ -208,7 +208,7 @@ private void InitializeOpenBuffers(SnapshotSpan triggerSpan)
 
                 foreach (var buffer in openBuffers)
                 {
-                    TryPopulateOpenTextBufferManagerForBuffer(buffer, buffer.AsTextContainer().GetRelatedDocuments());
+                    TryPopulateOpenTextBufferManagerForBuffer(buffer);
                 }
             }
 
@@ -230,14 +230,14 @@ private void InitializeOpenBuffers(SnapshotSpan triggerSpan)
             RenameTrackingDismisser.DismissRenameTracking(_workspace, _workspace.GetOpenDocumentIds());
         }
 
-        private bool TryPopulateOpenTextBufferManagerForBuffer(ITextBuffer buffer, IEnumerable<Document> documents)
+        private bool TryPopulateOpenTextBufferManagerForBuffer(ITextBuffer buffer)
         {
             AssertIsForeground();
             VerifyNotDismissed();
 
             if (_workspace.Kind == WorkspaceKind.Interactive)
             {
-                Debug.Assert(documents.Count() == 1); // No linked files.
+                Debug.Assert(buffer.GetRelatedDocuments().Count() == 1);
                 Debug.Assert(buffer.IsReadOnly(0) == buffer.IsReadOnly(Span.FromBounds(0, buffer.CurrentSnapshot.Length))); // All or nothing.
                 if (buffer.IsReadOnly(0))
                 {
@@ -245,11 +245,9 @@ private bool TryPopulateOpenTextBufferManagerForBuffer(ITextBuffer buffer, IEnum
                 }
             }
 
-            var documentSupportsFeatureService = _workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-
-            if (!_openTextBuffers.ContainsKey(buffer) && documentSupportsFeatureService.SupportsRename(buffer))
+            if (!_openTextBuffers.ContainsKey(buffer) && buffer.SupportsRename(_workspace))
             {
-                _openTextBuffers[buffer] = new OpenTextBufferManager(this, buffer, _workspace, documents, _textBufferFactoryService);
+                _openTextBuffers[buffer] = new OpenTextBufferManager(this, buffer, _workspace, _textBufferFactoryService);
                 return true;
             }
 
@@ -263,8 +261,7 @@ private void OnSubjectBuffersConnected(object sender, SubjectBuffersConnectedEve
             {
                 if (buffer.GetWorkspace() == _workspace)
                 {
-                    var documents = buffer.AsTextContainer().GetRelatedDocuments();
-                    if (TryPopulateOpenTextBufferManagerForBuffer(buffer, documents))
+                    if (TryPopulateOpenTextBufferManagerForBuffer(buffer))
                     {
                         _openTextBuffers[buffer].ConnectToView(e.TextView);
                     }

src/EditorFeatures/Core.Wpf/Suggestions/SuggestedActionsSource.cs

@@ -326,7 +326,7 @@ private SuggestedActionSet InlineActions(SuggestedActionSet actionSet)
                 this.AssertIsForeground();
 
                 if (_owner._codeFixService != null &&
-                    supportsFeatureService.SupportsCodeFixes(_subjectBuffer) &&
+                    _subjectBuffer.SupportsCodeFixes(workspace) &&
                     requestedActionCategories.Contains(PredefinedSuggestedActionCategoryNames.CodeFix))
                 {
                     // We only include suppressions if light bulb is asking for everything.
@@ -641,7 +641,7 @@ private static SuggestedActionSetPriority GetSuggestedActionSetPriority(CodeActi
 
                 if (workspace.Options.GetOption(EditorComponentOnOffOptions.CodeRefactorings) &&
                     _owner._codeRefactoringService != null &&
-                    supportsFeatureService.SupportsRefactorings(_subjectBuffer) &&
+                    _subjectBuffer.SupportsRefactorings(workspace) &&
                     requestedActionCategories.Contains(PredefinedSuggestedActionCategoryNames.Refactoring))
                 {
                     // It may seem strange that we kick off a task, but then immediately 'Wait' on 
@@ -791,10 +791,9 @@ private static SuggestedActionSetPriority GetSuggestedActionSetPriority(CodeActi
                 CancellationToken cancellationToken)
             {
                 var workspace = document.Project.Solution.Workspace;
-                var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
 
                 if (provider._codeFixService != null &&
-                    supportsFeatureService.SupportsCodeFixes(_subjectBuffer))
+                    _subjectBuffer.SupportsCodeFixes(workspace))
                 {
                     var result = await provider._codeFixService.GetMostSevereFixableDiagnosticAsync(
                             document, range.Span.ToTextSpan(), cancellationToken).ConfigureAwait(false);
@@ -830,11 +829,10 @@ private static SuggestedActionSetPriority GetSuggestedActionSetPriority(CodeActi
                 }
 
                 var workspace = document.Project.Solution.Workspace;
-                var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
 
                 if (document.Project.Solution.Options.GetOption(EditorComponentOnOffOptions.CodeRefactorings) &&
                     provider._codeRefactoringService != null &&
-                    supportsFeatureService.SupportsRefactorings(_subjectBuffer))
+                    _subjectBuffer.SupportsRefactorings(workspace))
                 {
                     if (await provider._codeRefactoringService.HasRefactoringsAsync(
                             document, selection.Value, cancellationToken).ConfigureAwait(false))

src/EditorFeatures/Core/CommandHandlers/GoToAdjacentMemberCommandHandler.cs

@@ -60,32 +60,48 @@ public bool ExecuteCommand(GoToPreviousMemberCommandArgs args, CommandExecutionC
 
         private VSCommanding.CommandState GetCommandStateImpl(EditorCommandArgs args)
         {
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
             var caretPoint = args.TextView.GetCaretPoint(args.SubjectBuffer);
-            return IsAvailable(document, caretPoint, args.SubjectBuffer) ? VSCommanding.CommandState.Available : VSCommanding.CommandState.Unspecified;
+            if (!IsAvailable(caretPoint, args.SubjectBuffer))
+            {
+                return VSCommanding.CommandState.Unspecified;
+            }
+
+            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
+            if (document?.SupportsSyntaxTree != true)
+            {
+                return VSCommanding.CommandState.Unspecified;
+            }
+
+            return VSCommanding.CommandState.Available;
         }
 
-        private static bool IsAvailable(Document document, SnapshotPoint? caretPoint, ITextBuffer subjectBuffer)
+        private static bool IsAvailable(SnapshotPoint? caretPoint, ITextBuffer subjectBuffer)
         {
-            if (document?.SupportsSyntaxTree != true)
+            if (!caretPoint.HasValue)
             {
                 return false;
             }
 
-            if (!caretPoint.HasValue)
+            if (!subjectBuffer.TryGetOwningWorkspace(out var workspace) ||
+                !subjectBuffer.SupportsNavigationToAnyPosition(workspace))
             {
                 return false;
             }
 
-            var documentSupportsFeatureService = document.Project.Solution.Workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            return documentSupportsFeatureService?.SupportsNavigationToAnyPosition(subjectBuffer) == true;
+            return true;
         }
 
         private bool ExecuteCommandImpl(EditorCommandArgs args, bool gotoNextMember, CommandExecutionContext context)
         {
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
             var caretPoint = args.TextView.GetCaretPoint(args.SubjectBuffer);
-            if (!IsAvailable(document, caretPoint, args.SubjectBuffer))
+            if (!IsAvailable(caretPoint, args.SubjectBuffer))
+            {
+                return false;
+            }
+
+
+            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
+            if (document?.SupportsSyntaxTree != true)
             {
                 return false;
             }

src/EditorFeatures/Core/GoToImplementation/GoToImplementationCommandHandler.cs

@@ -52,7 +52,7 @@ public bool ExecuteCommand(GoToImplementationCommandArgs args, CommandExecutionC
             using (context.OperationContext.AddScope(allowCancellation: true, EditorFeaturesResources.Locating_implementations))
             {
                 var subjectBuffer = args.SubjectBuffer;
-                if (!Workspace.TryGetWorkspace(subjectBuffer.AsTextContainer(), out var workspace))
+                if (!subjectBuffer.TryGetOwningWorkspace(out var workspace))
                 {
                     return false;
                 }

src/EditorFeatures/Core/Implementation/ChangeSignature/AbstractChangeSignatureCommandHandler.cs

@@ -30,20 +30,7 @@ public VSCommanding.CommandState GetCommandState(RemoveParametersCommandArgs arg
 
         private static VSCommanding.CommandState GetCommandState(ITextBuffer subjectBuffer)
         {
-            var document = subjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null ||
-                !document.Project.Solution.Workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            var supportsFeatureService = document.Project.Solution.Workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(subjectBuffer))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            return VSCommanding.CommandState.Available;
+            return IsAvailable(subjectBuffer) ? VSCommanding.CommandState.Available : VSCommanding.CommandState.Unspecified;
         }
 
         public bool ExecuteCommand(RemoveParametersCommandArgs args, CommandExecutionContext context)
@@ -52,22 +39,23 @@ public bool ExecuteCommand(RemoveParametersCommandArgs args, CommandExecutionCon
         public bool ExecuteCommand(ReorderParametersCommandArgs args, CommandExecutionContext context)
             => ExecuteCommand(args.TextView, args.SubjectBuffer, context);
 
-        private bool ExecuteCommand(ITextView textView, ITextBuffer subjectBuffer, CommandExecutionContext context)
+        private static bool IsAvailable(ITextBuffer subjectBuffer)
         {
-            using (context.OperationContext.AddScope(allowCancellation: true, FeaturesResources.Change_signature))
+            if (!subjectBuffer.TryGetOwningWorkspace(out var workspace) ||
+                !workspace.CanApplyChange(ApplyChangesKind.ChangeDocument) ||
+                !subjectBuffer.SupportsRefactorings(workspace))
             {
-                if (!Workspace.TryGetWorkspace(subjectBuffer.AsTextContainer(), out var workspace))
-                {
-                    return false;
-                }
+                return false;
+            }
 
-                if (!workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-                {
-                    return false;
-                }
+            return true;
+        }
 
-                var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-                if (!supportsFeatureService.SupportsRefactorings(subjectBuffer))
+        private bool ExecuteCommand(ITextView textView, ITextBuffer subjectBuffer, CommandExecutionContext context)
+        {
+            using (context.OperationContext.AddScope(allowCancellation: true, FeaturesResources.Change_signature))
+            {
+                if (IsAvailable(subjectBuffer))
                 {
                     return false;
                 }

src/EditorFeatures/Core/Implementation/EncapsulateField/AbstractEncapsulateFieldCommandHandler.cs

@@ -37,15 +37,7 @@ internal abstract class AbstractEncapsulateFieldCommandHandler : VSCommanding.IC
 
         public bool ExecuteCommand(EncapsulateFieldCommandArgs args, CommandExecutionContext context)
         {
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null)
-            {
-                return false;
-            }
-
-            var workspace = document.Project.Solution.Workspace;
-            var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(args.SubjectBuffer))
+            if (!args.SubjectBuffer.SupportsRefactorings())
             {
                 return false;
             }
@@ -127,19 +119,7 @@ private bool Execute(EncapsulateFieldCommandArgs args, IUIThreadOperationScope w
 
         public VSCommanding.CommandState GetCommandState(EncapsulateFieldCommandArgs args)
         {
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null)
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            var supportsFeatureService = document.Project.Solution.Workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(args.SubjectBuffer))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            return VSCommanding.CommandState.Available;
+            return args.SubjectBuffer.SupportsRefactorings() ? VSCommanding.CommandState.Available : VSCommanding.CommandState.Unspecified;
         }
     }
 }

src/EditorFeatures/Core/Implementation/ExtractInterface/AbstractExtractInterfaceCommandHandler.cs

@@ -10,6 +10,7 @@
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.Commanding;
+using Microsoft.VisualStudio.Text;
 using Microsoft.VisualStudio.Text.Editor.Commanding.Commands;
 using Roslyn.Utilities;
 using VSCommanding = Microsoft.VisualStudio.Commanding;
@@ -29,21 +30,7 @@ protected AbstractExtractInterfaceCommandHandler(IThreadingContext threadingCont
 
         public VSCommanding.CommandState GetCommandState(ExtractInterfaceCommandArgs args)
         {
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null ||
-                !document.Project.Solution.Workspace.CanApplyChange(ApplyChangesKind.AddDocument) ||
-                !document.Project.Solution.Workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            var supportsFeatureService = document.Project.Solution.Workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(args.SubjectBuffer))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            return VSCommanding.CommandState.Available;
+            return IsAvailable(args.SubjectBuffer, out var _) ? VSCommanding.CommandState.Available : VSCommanding.CommandState.Unspecified;
         }
 
         public bool ExecuteCommand(ExtractInterfaceCommandArgs args, CommandExecutionContext context)
@@ -51,19 +38,7 @@ public bool ExecuteCommand(ExtractInterfaceCommandArgs args, CommandExecutionCon
             using (context.OperationContext.AddScope(allowCancellation: true, EditorFeaturesResources.Extract_Interface))
             {
                 var subjectBuffer = args.SubjectBuffer;
-                if (!Workspace.TryGetWorkspace(subjectBuffer.AsTextContainer(), out var workspace))
-                {
-                    return false;
-                }
-
-                if (!workspace.CanApplyChange(ApplyChangesKind.AddDocument) ||
-                    !workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-                {
-                    return false;
-                }
-
-                var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-                if (!supportsFeatureService.SupportsRefactorings(subjectBuffer))
+                if (!IsAvailable(subjectBuffer, out var workspace))
                 {
                     return false;
                 }
@@ -110,5 +85,20 @@ public bool ExecuteCommand(ExtractInterfaceCommandArgs args, CommandExecutionCon
                 return true;
             }
         }
+
+        private static bool IsAvailable(ITextBuffer subjectBuffer, out Workspace workspace)
+        {
+            if (!subjectBuffer.TryGetOwningWorkspace(out var retrievedWorkspace) ||
+                    !retrievedWorkspace.CanApplyChange(ApplyChangesKind.AddDocument) ||
+                    !retrievedWorkspace.CanApplyChange(ApplyChangesKind.ChangeDocument) ||
+                    !subjectBuffer.SupportsRefactorings(retrievedWorkspace))
+            {
+                workspace = retrievedWorkspace;
+                return false;
+            }
+
+            workspace = retrievedWorkspace;
+            return true;
+        }
     }
 }

src/EditorFeatures/Core/Implementation/ExtractMethod/AbstractExtractMethodCommandHandler.cs

@@ -50,19 +50,9 @@ public VSCommanding.CommandState GetCommandState(ExtractMethodCommandArgs args)
                 return VSCommanding.CommandState.Unspecified;
             }
 
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null)
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            if (!document.Project.Solution.Workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return VSCommanding.CommandState.Unspecified;
-            }
-
-            var supportsFeatureService = document.Project.Solution.Workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(args.SubjectBuffer))
+            if (!args.SubjectBuffer.TryGetOwningWorkspace(out var workspace) ||
+                !workspace.CanApplyChange(ApplyChangesKind.ChangeDocument) ||
+                !args.SubjectBuffer.SupportsRefactorings(workspace))
             {
                 return VSCommanding.CommandState.Unspecified;
             }
@@ -79,20 +69,7 @@ public bool ExecuteCommand(ExtractMethodCommandArgs args, CommandExecutionContex
                 _renameService.ActiveSession.Commit();
             }
 
-            var subjectBuffer = args.SubjectBuffer;
-            if (!Workspace.TryGetWorkspace(subjectBuffer.AsTextContainer(), out var workspace))
-            {
-                return false;
-            }
-
-            var supportsFeatureService = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
-            if (!supportsFeatureService.SupportsRefactorings(subjectBuffer))
-            {
-                return false;
-            }
-
-            var document = subjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
-            if (document == null)
+            if (!args.SubjectBuffer.SupportsRefactorings())
             {
                 return false;
             }

src/EditorFeatures/Core/Implementation/Organizing/OrganizeDocumentCommandHandler.cs

@@ -77,26 +77,23 @@ private VSCommanding.CommandState GetCommandState(EditorCommandArgs args, Func<I
         private bool IsCommandSupported(EditorCommandArgs args, out Workspace workspace)
         {
             workspace = null;
-            var document = args.SubjectBuffer.AsTextContainer().GetOpenDocumentInCurrentContext();
-
-            if (document == null)
+            if (args.SubjectBuffer.TryGetOwningWorkspace(out var retrievedWorkspace))
             {
-                return false;
-            }
-
-            workspace = document.Project.Solution.Workspace;
+                workspace = retrievedWorkspace;
+                if (!workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
+                {
+                    return false;
+                }
 
-            if (!workspace.CanApplyChange(ApplyChangesKind.ChangeDocument))
-            {
-                return false;
-            }
+                if (workspace.Kind == WorkspaceKind.MiscellaneousFiles)
+                {
+                    return false;
+                }
 
-            if (workspace.Kind == WorkspaceKind.MiscellaneousFiles)
-            {
-                return false;
+                return args.SubjectBuffer.SupportsRefactorings(workspace);
             }
 
-            return workspace.Services.GetService<ITextBufferSupportsFeatureService>().SupportsRefactorings(args.SubjectBuffer);
+            return false;
         }
 
         public bool ExecuteCommand(SortAndRemoveUnnecessaryImportsCommandArgs args, CommandExecutionContext context)

src/EditorFeatures/Core/Shared/Extensions/ITextBufferExtensions.cs

@@ -43,5 +43,63 @@ internal static bool GetFeatureOnOffOption(this ITextBuffer buffer, PerLanguageO
                 throw ExceptionUtilities.Unreachable;
             }
         }
+
+        internal static bool TryGetOwningWorkspace(this ITextBuffer buffer, out Workspace workspace)
+        {
+            workspace = null;
+            if (Workspace.TryGetWorkspace(buffer.AsTextContainer(), out var retrievedWorkspace))
+            {
+                workspace = retrievedWorkspace;
+            }
+
+            return workspace != null;
+        }
+
+        /// <summary>
+        /// Checks if the buffer supports refactorings.
+        /// Additionally retrieves the workspace for the buffer.
+        /// </summary>
+        internal static bool SupportsRefactorings(this ITextBuffer buffer)
+        {
+            return buffer.TryGetOwningWorkspace(out var workspace) && buffer.SupportsRefactorings(workspace);
+        }
+
+        /// <summary>
+        /// Checks if a buffer supports refactorings.
+        /// </summary>
+        internal static bool SupportsRefactorings(this ITextBuffer buffer, Workspace workspace)
+        {
+            return TryGetSupportsFeatureService(workspace, out var service) && service.SupportsRefactorings(buffer);
+        }
+
+        /// <summary>
+        /// Checks if a buffer supports rename.
+        /// </summary>
+        internal static bool SupportsRename(this ITextBuffer buffer, Workspace workspace)
+        {
+            return TryGetSupportsFeatureService(workspace, out var service) && service.SupportsRename(buffer);
+        }
+
+        /// <summary>
+        /// Checks if a buffer supports code fixes.
+        /// </summary>
+        internal static bool SupportsCodeFixes(this ITextBuffer buffer, Workspace workspace)
+        {
+            return TryGetSupportsFeatureService(workspace, out var service) && service.SupportsCodeFixes(buffer);
+        }
+
+        /// <summary>
+        /// Checks if a buffer supports navigation.
+        /// </summary>
+        internal static bool SupportsNavigationToAnyPosition(this ITextBuffer buffer, Workspace workspace)
+        {
+            return TryGetSupportsFeatureService(workspace, out var service) && service.SupportsNavigationToAnyPosition(buffer);
+        }
+
+        private static bool TryGetSupportsFeatureService(Workspace workspace, out ITextBufferSupportsFeatureService service)
+        {
+            service = workspace.Services.GetService<ITextBufferSupportsFeatureService>();
+            return service != null;
+        }
     }
 }

src/VisualStudio/Core/Def/Implementation/VisualStudioTextBufferSupportsFeatureService.cs

@@ -27,7 +27,7 @@ public bool SupportsRefactorings(ITextBuffer textBuffer)
 
         public bool SupportsRename(ITextBuffer textBuffer)
         {
-            var sourceTextContainer = textBuffer.CurrentSnapshot.AsText().Container;
+            var sourceTextContainer = textBuffer.AsTextContainer();
             if (Workspace.TryGetWorkspace(sourceTextContainer, out var workspace))
             {
                 return workspace.GetRelatedDocumentIds(sourceTextContainer)
@@ -45,7 +45,7 @@ public bool SupportsNavigationToAnyPosition(ITextBuffer textBuffer)
 
         private static ContainedDocument GetContainedDocument(ITextBuffer textBuffer)
         {
-            var sourceTextContainer = textBuffer.CurrentSnapshot.AsText().Container;
+            var sourceTextContainer = textBuffer.AsTextContainer();
             if (Workspace.TryGetWorkspace(sourceTextContainer, out var workspace)
                 && workspace is VisualStudioWorkspaceImpl vsWorkspace)
             {