internal void RemoveTagger(SpellCheckerTagger tagger)
        {
            _activeTaggers.Remove(tagger);

            if (_activeTaggers.Count == 0)
            {
                // Last tagger was disposed of. This is means there are no longer any open views on the buffer so we can safely shut down
                // spell checking for that buffer.
                _buffer.ChangedLowPriority -= this.OnBufferChange;

                _provider.RemoveSpellChecker(this);

                _isDisposed = true;

                _buffer.Properties.RemoveProperty(typeof(SpellChecker));

                IDisposable classifierDispose = _classifier as IDisposable;
                if (classifierDispose != null)
                {
                    classifierDispose.Dispose();
                }

                _classifier = null;
            }
        }
        /// <summary>
        /// Create a tagger that does spell checking on the view/buffer combination.
        /// </summary>
        public ITagger <T> CreateTagger <T>(ITextView textView, ITextBuffer buffer) where T : ITag
        {
            ITagger <T> tagger = null;

            // Only attempt to spell check on the view's edit buffer (and multiple views could have that buffer open simultaneously so
            // only create one instance of the spell checker.
            if ((buffer == textView.TextBuffer) && (typeof(T) == typeof(IErrorTag)))
            {
                var spellChecker = buffer.Properties.GetOrCreateSingletonProperty(typeof(SpellChecker), () => new SpellChecker(this, textView, buffer));

                // This is a thin wrapper around the SpellChecker that can be disposed of without shutting down the SpellChecker
                // (unless it was the last tagger on the spell checker).
                tagger = new SpellCheckerTagger(spellChecker) as ITagger <T>;
            }

            return(tagger);
        }
        internal void AddTagger(SpellCheckerTagger tagger)
        {
            _activeTaggers.Add(tagger);

            if (_activeTaggers.Count == 1)
            {
                // First tagger created ... start doing stuff.
                _classifier = _provider.ClassifierAggregatorService.GetClassifier(_buffer);

                _buffer.ChangedLowPriority += this.OnBufferChange;

                _dirtySpans = new NormalizedSnapshotSpanCollection(new SnapshotSpan(_currentSnapshot, 0, _currentSnapshot.Length));

                _provider.AddSpellChecker(this);

                this.KickUpdate();
            }
        }