public Tagger(
IThreadingContext threadingContext,
IAsynchronousOperationListener listener,
IForegroundNotificationService notificationService,
TagSource tagSource,
ITextBuffer subjectBuffer)
{
Contract.ThrowIfNull(subjectBuffer);
_subjectBuffer = subjectBuffer;
_cancellationTokenSource = new CancellationTokenSource();
_batchChangeNotifier = new BatchChangeNotifier(
threadingContext,
subjectBuffer, listener, notificationService, NotifyEditorNow, _cancellationTokenSource.Token);
_tagSource = tagSource;
_tagSource.OnTaggerAdded(this);
_tagSource.TagsChangedForBuffer += OnTagsChangedForBuffer;
_tagSource.Paused += OnPaused;
_tagSource.Resumed += OnResumed;
// There is a many-to-one relationship between Taggers and TagSources. i.e. one
// tag-source can be used by many Taggers. As such, we may be a tagger that is
// wrapping a tag-source that has already produced tags and had sent out the
// notifications about those tags.
//
// However, we still want to notify the code consuming us that we have tags to
// display. That way, tags can display as soon as possible when someone creates
// a new tagger for a view/buffer.
//
// Note: we have to do this in the future instead of right now because we haven't
// even been returned to the caller for them to hook up to change notifications
// from us.
notificationService.RegisterNotification(
() =>
{
if (this.TagsChanged == null)
{
// don't bother reporting tags if no one is listening.
return;
}
var tags = _tagSource.TryGetTagIntervalTreeForBuffer(_subjectBuffer);
if (tags != null)
{
var collection = new NormalizedSnapshotSpanCollection(
tags.GetSpans(_subjectBuffer.CurrentSnapshot).Select(ts => ts.Span));
this.NotifyEditorNow(collection);
}
},
listener.BeginAsyncOperation(GetType().FullName + ".ctor-ReportInitialTags"),
_cancellationTokenSource.Token);
}
private IEnumerable <ITagSpan <TTag> > GetTagsWorker(
NormalizedSnapshotSpanCollection requestedSpans,
bool accurate,
CancellationToken cancellationToken)
{
if (requestedSpans.Count == 0)
{
return(SpecializedCollections.EmptyEnumerable <ITagSpan <TTag> >());
}
var buffer = requestedSpans.First().Snapshot.TextBuffer;
var tags = accurate
? _tagSource.GetAccurateTagIntervalTreeForBuffer(buffer, cancellationToken)
: _tagSource.TryGetTagIntervalTreeForBuffer(buffer);
if (tags == null)
{
return(SpecializedCollections.EmptyEnumerable <ITagSpan <TTag> >());
}
return(tags.GetIntersectingTagSpans(requestedSpans));
}
