move comment token retrieve API to new API

src/VisualStudio/Core/Def/Implementation/TaskList/CommentTaskTokenSerializer.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Composition;
-using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Editor.Implementation.TodoComments;
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Options.Providers;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Options;
 using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Shell.Interop;
-using Roslyn.Utilities;
 
 namespace Microsoft.VisualStudio.LanguageServices.Implementation.TaskList
 {
     [ExportOptionSerializer(TodoCommentOptions.OptionName), Shared]
     internal class CommentTaskTokenSerializer : IOptionSerializer
     {
-        // it seems VS doesn't give a way to get notified if this setting gets changed.
-        // so we will only read it once and keep using it until next vs run
-        private readonly string _taskTokenList;
+        private readonly ITaskList _taskList;
+        private readonly IOptionService _optionService;
+
+        private string _lastCommentTokenCache = null;
 
         [ImportingConstructor]
-        public CommentTaskTokenSerializer(SVsServiceProvider serviceProvider)
+        public CommentTaskTokenSerializer(
+            SVsServiceProvider serviceProvider, IOptionService optionService)
         {
-            var tokenInfo = serviceProvider.GetService(typeof(SVsTaskList)) as IVsCommentTaskInfo;
+            _optionService = optionService;
+
+            _taskList = serviceProvider.GetService(typeof(SVsTaskList)) as ITaskList;
+            _lastCommentTokenCache = GetTaskTokenList(_taskList);
 
             // The SVsTaskList may not be available (e.g. during "devenv /build")
-            _taskTokenList = tokenInfo != null ? GetTaskTokenList(tokenInfo) : string.Empty;
+            if (_taskList != null)
+            {
+                _taskList.PropertyChanged += OnPropertyChanged;
+            }
         }
 
         public bool TryFetch(OptionKey optionKey, out object value)
@@ -37,7 +44,7 @@ public bool TryFetch(OptionKey optionKey, out object value)
                 return false;
             }
 
-            value = _taskTokenList;
+            value = _lastCommentTokenCache;
             return true;
         }
 
@@ -47,44 +54,49 @@ public bool TryPersist(OptionKey optionKey, object value)
             return false;
         }
 
-        public static string GetTaskTokenList(IVsCommentTaskInfo tokenInfo)
+        private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
         {
-            int tokenCount;
-            if (Succeeded(tokenInfo.TokenCount(out tokenCount)) && tokenCount > 0)
+            if (e.PropertyName != nameof(ITaskList.CommentTokens))
             {
-                var tokens = new IVsCommentTaskToken[tokenCount];
-                var tokensEnum = default(IVsEnumCommentTaskTokens);
-                if (Succeeded(tokenInfo.EnumTokens(out tokensEnum)))
-                {
-                    uint count;
-                    if (Succeeded(tokensEnum.Next((uint)tokenCount, tokens, out count)))
-                    {
-                        Contract.Requires(tokenCount == count);
-
-                        string text;
-                        var priority = new VSTASKPRIORITY[1];
-                        var result = new List<string>();
-                        foreach (var token in tokens)
-                        {
-                            if (Succeeded(token.Text(out text)) &&
-                                Succeeded(token.Priority(priority)) &&
-                                !string.IsNullOrWhiteSpace(text))
-                            {
-                                result.Add(string.Format("{0}:{1}", text, (int)priority[0]));
-                            }
-                        }
-
-                        return string.Join("|", result);
-                    }
-                }
+                return;
+            }
+
+            var commentString = GetTaskTokenList(_taskList);
+
+            var optionSet = _optionService.GetOptions();
+            var optionValue = optionSet.GetOption(TodoCommentOptions.TokenList);
+            if (optionValue == commentString)
+            {
+                return;
             }
 
-            return string.Empty;
+            // cache last result
+            _lastCommentTokenCache = commentString;
+
+            // let people to know that comment string has changed
+            _optionService.SetOptions(optionSet.WithChangedOption(TodoCommentOptions.TokenList, _lastCommentTokenCache));
         }
 
-        private static bool Succeeded(int hr)
+        private static string GetTaskTokenList(ITaskList taskList)
         {
-            return hr == VSConstants.S_OK;
+            var commentTokens = taskList?.CommentTokens;
+            if (commentTokens == null || commentTokens.Count == 0)
+            {
+                return string.Empty;
+            }
+
+            var result = new List<string>();
+            foreach (var commentToken in commentTokens)
+            {
+                if (string.IsNullOrWhiteSpace(commentToken.Text))
+                {
+                    continue;
+                }
+
+                result.Add($"{commentToken.Text}:{((int)commentToken.Priority).ToString()}");
+            }
+
+            return string.Join("|", result);
         }
     }
 }

src/VisualStudio/Core/Def/Implementation/TaskList/VisualStudioTodoTaskList.cs

@@ -20,7 +20,7 @@
 namespace Microsoft.VisualStudio.LanguageServices.Implementation.TaskList
 {
     [Export(typeof(VisualStudioTodoTaskList))]
-    internal partial class VisualStudioTodoTaskList : AbstractVisualStudioTaskList, IVsTaskListEvents
+    internal partial class VisualStudioTodoTaskList : AbstractVisualStudioTaskList
     {
         private readonly Dictionary<object, IVsTaskItem[]> _todoItemMap = new Dictionary<object, IVsTaskItem[]>();
         private readonly IOptionService _optionService;
@@ -142,22 +142,6 @@ private void UpdateTodoTaskList()
             }, TaggerConstants.MediumDelay, this.Listener.BeginAsyncOperation("RefreshTaskList"));
         }
 
-        public int OnCommentTaskInfoChanged()
-        {
-            var tokenInfo = ServiceProvider.GetService(typeof(SVsTaskList)) as IVsCommentTaskInfo;
-            var commentString = CommentTaskTokenSerializer.GetTaskTokenList(tokenInfo);
-
-            var optionSet = _optionService.GetOptions();
-            var optionValue = optionSet.GetOption(TodoCommentOptions.TokenList);
-            if (optionValue == commentString)
-            {
-                return VSConstants.S_OK;
-            }
-
-            _optionService.SetOptions(optionSet.WithChangedOption(TodoCommentOptions.TokenList, commentString));
-            return VSConstants.S_OK;
-        }
-
         internal void TestOnly_Enable()
         {
             if (!ErrorListInstalled)