Visual Studio SDK - IViewTagAggregatorFactoryService.CreateTagAggregator導致異常

Question

我需要獲取當前文本視圖中ITextSnapshotLine行的分類標記。

首先，我得到了積極的文本視圖：

public static IWpfTextView GetTextView() 
{ 
    var textManager = (IVsTextManager)ServiceProvider.GlobalProvider.GetService(typeof(SVsTextManager)); 
    IVsTextView vTextView = null; 
    var mustHaveFocus = 1; 
    textManager.GetActiveView(mustHaveFocus, null, out vTextView); 
    var userData = vTextView as IVsUserData; 
    if (userData != null) 
    { 
     IWpfTextViewHost viewHost; 
     object holder; 
     var guidViewHost = DefGuidList.guidIWpfTextViewHost; 
     userData.GetData(ref guidViewHost, out holder); 
     viewHost = (IWpfTextViewHost)holder; 
     var textView = viewHost.TextView; 
     return textView; 
    } 

    return null; 
} 

然後，我得到的從視圖ITextViewLine線收集和調用GetClassificationTags每一種方法：

GetClassificationTags(new SnapshotSpan(line.Start, line.Length), textView) 

的方法看起來像這個：

public IEnumerable<IMappingTagSpan<IClassificationTag>> GetClassificationTags(SnapshotSpan span, ITextView textView) 
{ 
    var snapshot = textView.TextSnapshot; 

    var componentModel = (IComponentModel)ServiceProvider.GlobalProvider.GetService(typeof(SComponentModel)); 
    var exportProvider = componentModel.DefaultExportProvider; 

    var viewTagAggregatorFactoryService = exportProvider.GetExportedValue<IViewTagAggregatorFactoryService>(); 

    var tagAggregator = viewTagAggregatorFactoryService.CreateTagAggregator<IClassificationTag>(textView); 

    return tagAggregator.GetTags(span); 
} 

因此，我有一切正確分類。但是，Visual Studio引發異常並將其記錄到ActivityLog.xml文件中。這種情況只有在第一次對所有行進行分類後纔會發生。在日誌文件中的信息說：

System.InvalidOperationException: 
Unexpected false
 
at Roslyn.Utilities.Contract.ThrowIfFalse(Boolean condition, String message)
 
at Microsoft.CodeAnalysis.Editor.Implementation.Diagnostics.AbstractDiagnosticsTaggerProvider`1.CreateTagger[T](ITextBuffer buffer)
 
at Microsoft.CodeAnalysis.Editor.Implementation.Diagnostics.AbstractDiagnosticsTaggerProvider`1.Microsoft.VisualStudio.Text.Tagging.ITaggerProvider.CreateTagger[T](ITextBuffer buffer)
 
at Microsoft.VisualStudio.Text.Tagging.Implementation.TagAggregator`1.GatherTaggers(ITextBuffer textBuffer) 

我注意到異常沒有被註釋掉下面的行之後拋出：

var tagAggregator = viewTagAggregatorFactoryService.CreateTagAggregator<IClassificationTag>(textView); 

有時候，也有此異常日誌文件：

System.InvalidOperationException: Unexpected false
 
at Roslyn.Utilities.Contract.ThrowIfFalse(Boolean condition, String message)
 
at Microsoft.CodeAnalysis.Editor.Tagging.AbstractAsynchronousTaggerProvider`1.TagSource.GetTagIntervalTreeForBuffer(ITextBuffer buffer)
 
at Microsoft.CodeAnalysis.Editor.Tagging.AbstractAsynchronousTaggerProvider`1.Tagger.GetTagsWorker(NormalizedSnapshotSpanCollection requestedSpans, Boolean accurate, CancellationToken cancellationToken)
 
at Microsoft.CodeAnalysis.Editor.Tagging.AbstractAsynchronousTaggerProvider`1.Tagger.GetTags(NormalizedSnapshotSpanCollection requestedSpans)
 
at Microsoft.VisualStudio.Text.Tagging.Implementation.TagAggregator`1.<GetTagsForBuffer>d__38.MoveNext() 

我的問題是：什麼導致這個異常，我該如何擺脫它？

Answer 1

The code is open source，你可以看看。我的猜測是你在後臺線程上嘗試。