C# SnapshotPoint类代码示例

 public void CreateForAllPoints_Line_EndOfSnapshot()
 {
     Create("cat", "dog");
     var point = new SnapshotPoint(_textBuffer.CurrentSnapshot, _textBuffer.CurrentSnapshot.Length);
     var visualSpan = VisualSpan.CreateForAllPoints(VisualKind.Line, point, point);
     Assert.AreEqual(1, visualSpan.AsLine().LineRange.LastLineNumber);
 }

        public override Span? GetInvocationSpan(string text, int linePosition, SnapshotPoint position)
        {
            // If this isn't the beginning of the line, stop immediately.
            var quote = text.SkipWhile(Char.IsWhiteSpace).FirstOrDefault();
            if (quote != '"' && quote != '\'')
                return null;

            // If it is, make sure it's also the beginning of a function.
            var prevLine = EnumeratePrecedingLineTokens(position).GetEnumerator();

            // If we are at the beginning of the file, that is also fine.
            if (prevLine.MoveNext())
            {
                // Check that the previous line contains "function", then
                // eventually ") {" followed by the end of the line.
                if (!ConsumeToToken(prevLine, "function", "keyword") || !ConsumeToToken(prevLine, ")", "operator"))
                    return null;
                if (!prevLine.MoveNext() || prevLine.Current.Span.GetText() != "{")
                    return null;
                // If there is non-comment code after the function, stop
                if (prevLine.MoveNext() && SkipComments(prevLine))
                    return null;
            }

            var startIndex = text.TakeWhile(Char.IsWhiteSpace).Count();
            var endIndex = linePosition;

            // Consume the auto-added close quote, if present.
            // If range ends at the end of the line, we cannot
            // check this.
            if (endIndex < text.Length && text[endIndex] == quote)
                endIndex++;
            return Span.FromBounds(startIndex, endIndex);
        }

        protected override bool Execute(uint commandId, uint nCmdexecopt, IntPtr pvaIn, IntPtr pvaOut)
        {
            if (_broker.IsCompletionActive(TextView) || !IsValidTextBuffer() || !WESettings.GetBoolean(WESettings.Keys.EnableEnterFormat))
                return false;

            int position = TextView.Caret.Position.BufferPosition.Position;
            SnapshotPoint point = new SnapshotPoint(TextView.TextBuffer.CurrentSnapshot, position);
            IWpfTextViewLine line = TextView.GetTextViewLineContainingBufferPosition(point);

            ElementNode element = null;
            AttributeNode attr = null;

            _tree.GetPositionElement(position, out element, out attr);

            if (element == null ||
                _tree.IsDirty ||
                element.Parent == null ||
                line.End.Position == position || // caret at end of line (TODO: add ignore whitespace logic)
                TextView.TextBuffer.CurrentSnapshot.GetText(element.InnerRange.Start, element.InnerRange.Length).Trim().Length == 0)
                return false;

            UpdateTextBuffer(element, position);

            return false;
        }

 /// <summary>
 /// Removes a token using the enhanced token stream class.
 /// </summary>
 /// <param name="sql"></param>
 /// <param name="position"></param>
 /// <returns></returns>
 private CommonTokenStream RemoveToken(string sql, SnapshotPoint snapPos)
 {
   MemoryStream ms = new MemoryStream(ASCIIEncoding.ASCII.GetBytes(sql));
   CaseInsensitiveInputStream input = new CaseInsensitiveInputStream(ms);
   //ANTLRInputStream input = new ANTLRInputStream(ms);
   Version ver = LanguageServiceUtil.GetVersion(LanguageServiceUtil.GetConnection().ServerVersion);
   MySQLLexer lexer = new MySQLLexer(input);
   lexer.MySqlVersion = ver;
   TokenStreamRemovable tokens = new TokenStreamRemovable(lexer);      
   IToken tr = null;
   int position = snapPos.Position;
   tokens.Fill();      
   if (!char.IsWhiteSpace(snapPos.GetChar()))
   {
     foreach (IToken t in tokens.GetTokens())
     {
       if ((t.StartIndex <= position) && (t.StopIndex >= position))
       {
         tr = t;
         break;
       }
     }
     tokens.Remove(tr);
   }
   return tokens;
 }    

        public override Span? GetInvocationSpan(string text, int linePosition, SnapshotPoint position)
        {
            // Find the quoted string inside function call
            int startIndex = text.LastIndexOf(FunctionName + "(", linePosition, StringComparison.Ordinal);
            if (startIndex < 0)
                return null;
            startIndex += FunctionName.Length + 1;
            startIndex += text.Skip(startIndex).TakeWhile(Char.IsWhiteSpace).Count();

            if (linePosition <= startIndex || (text[startIndex] != '"' && text[startIndex] != '\''))
                return null;

            var endIndex = text.IndexOf(text[startIndex] + ")", startIndex, StringComparison.OrdinalIgnoreCase);
            if (endIndex < 0)
                endIndex = startIndex + text.Skip(startIndex + 1).TakeWhile(c => Char.IsLetterOrDigit(c) || Char.IsWhiteSpace(c) || c == '-' || c == '_').Count() + 1;
            else if (linePosition > endIndex + 1)
                return null;

            // Consume the auto-added close quote, if present.
            // If range ends at the end of the line, we cannot
            // check this.
            if (endIndex < text.Length && text[endIndex] == text[startIndex])
                endIndex++;


            return Span.FromBounds(startIndex, endIndex);
        }

        /// <summary>
        /// Is the provided SnapshotPoint preceded by the '+= SomeEventType(Some_HandlerName' line
        /// </summary>
        private bool IsPreceededByEventAddSyntax(SnapshotSpan span)
        {
            // First find the last + character
            var snapshot = span.Snapshot;
            SnapshotPoint? plusPoint = null;
            for (int i = span.Length - 1; i >= 0; i--)
            {
                var position = span.Start.Position + i;
                var point = new SnapshotPoint(snapshot, position);
                if (point.GetChar() == '+')
                {
                    plusPoint = point;
                    break;
                }
            }

            if (plusPoint == null)
            {
                return false;
            }

            var eventSpan = new SnapshotSpan(plusPoint.Value, span.End);
            var eventText = eventSpan.GetText();
            return 
                s_fullEventSyntaxRegex.IsMatch(eventText) ||
                s_shortEventSyntaxRegex.IsMatch(eventText);
        }

 public FakeTextSnapshotLine(ITextSnapshot snapshot, string text, int position, int lineNumber)
 {
     Snapshot = snapshot;
     this._text = text;
     LineNumber = lineNumber;
     Start = new SnapshotPoint(snapshot, position);
 }

        public bool TryCreateSession(ITextView textView, SnapshotPoint openingPoint, char openingBrace, char closingBrace, out IBraceCompletionSession session)
        {
            this.AssertIsForeground();

            var textSnapshot = openingPoint.Snapshot;
            var document = textSnapshot.GetOpenDocumentInCurrentContextWithChanges();
            if (document != null)
            {
                var editorSessionFactory = document.GetLanguageService<IEditorBraceCompletionSessionFactory>();
                if (editorSessionFactory != null)
                {
                    // Brace completion is (currently) not cancellable.
                    var cancellationToken = CancellationToken.None;

                    var editorSession = editorSessionFactory.TryCreateSession(document, openingPoint, openingBrace, cancellationToken);
                    if (editorSession != null)
                    {
                        var undoHistory = _undoManager.GetTextBufferUndoManager(textView.TextBuffer).TextBufferUndoHistory;
                        session = new BraceCompletionSession(
                            textView, openingPoint.Snapshot.TextBuffer, openingPoint, openingBrace, closingBrace,
                            undoHistory, _editorOperationsFactoryService,
                            editorSession);
                        return true;
                    }
                }
            }

            session = null;
            return false;
        }

        public static SnapshotPoint? MapUpOrDownToBuffer(this IBufferGraph bufferGraph, SnapshotPoint point, ITextBuffer targetBuffer)
        {
            var direction = ClassifyBufferMapDirection(point.Snapshot.TextBuffer, targetBuffer);
            switch (direction)
            {
                case BufferMapDirection.Identity:
                    return point;

                case BufferMapDirection.Down:
                    {
                        // TODO (https://github.com/dotnet/roslyn/issues/5281): Remove try-catch.
                        try
                        {
                            return bufferGraph.MapDownToInsertionPoint(point, PointTrackingMode.Positive, s => s == targetBuffer.CurrentSnapshot);
                        }
                        catch (ArgumentOutOfRangeException) when (bufferGraph.TopBuffer.ContentType.TypeName == "Interactive Content")
                        {
                            // Suppress this to work around DevDiv #144964.
                            // Note: Other callers might be affected, but this is the narrowest workaround for the observed problems.
                            // A fix is already being reviewed, so a broader change is not required.
                            return null;
                        }
                    }

                case BufferMapDirection.Up:
                    {
                        return bufferGraph.MapUpToBuffer(point, PointTrackingMode.Positive, PositionAffinity.Predecessor, targetBuffer);
                    }

                default:
                    return null;
            }
        }

        // returns true if brace is actually a brace.
        private bool FindOtherBrace(SnapshotPoint possibleBrace, out SnapshotPoint? otherBrace)
        {
            otherBrace = null;
              var rainbow = this.textBuffer.Get<RainbowProvider>();
              if ( rainbow == null ) {
            return false;
              }
              if ( !possibleBrace.IsValid() ) {
            return false;
              }

              if ( !rainbow.BraceCache.Language.BraceList.Contains(possibleBrace.GetChar()) ) {
            return false;
              }
              var bracePair = rainbow.BraceCache.GetBracePair(possibleBrace);
              if ( bracePair == null ) {
            return true;
              }
              if ( possibleBrace.Position == bracePair.Item1.Position ) {
            otherBrace = bracePair.Item2.ToPoint(possibleBrace.Snapshot);
              } else {
            otherBrace = bracePair.Item1.ToPoint(possibleBrace.Snapshot);
              }
              return true;
        }

        private bool Indent()
        {
            int position = _textView.Caret.Position.BufferPosition.Position;


            if (position == 0 || position == _textView.TextBuffer.CurrentSnapshot.Length || _textView.Selection.SelectedSpans[0].Length > 0)
                return false;

            char before = _textView.TextBuffer.CurrentSnapshot.GetText(position - 1, 1)[0];
            char after = _textView.TextBuffer.CurrentSnapshot.GetText(position, 1)[0];

            if (before == '{' && after == '}')
            {
                EditorExtensionsPackage.DTE.UndoContext.Open("Smart indent");

                _textView.TextBuffer.Insert(position, Environment.NewLine + '\t');
                SnapshotPoint point = new SnapshotPoint(_textView.TextBuffer.CurrentSnapshot, position);
                _textView.Selection.Select(new SnapshotSpan(point, 4), true);

                EditorExtensionsPackage.ExecuteCommand("Edit.FormatSelection");

                _textView.Selection.Clear();
                SendKeys.Send("{ENTER}");

                EditorExtensionsPackage.DTE.UndoContext.Close();

                return true;
            }

            return false;
        }

		public TextExtent GetExtentOfWord(SnapshotPoint currentPosition) {
			if (currentPosition.Snapshot?.TextBuffer != textBuffer)
				throw new ArgumentException();
			if (currentPosition.Position >= currentPosition.Snapshot.Length)
				return new TextExtent(new SnapshotSpan(currentPosition, currentPosition), true);
			return new TextExtent(new SnapshotSpan(currentPosition, currentPosition + 1), true);
		}

        public static string PeekString(this ITextSnapshot snapshot, SnapshotPoint point, int length)
        {
            if (point >= snapshot.Length)
                return null;

            return new SnapshotSpan(point, Math.Min(length, snapshot.Length - point)).GetText();
        }

        private ScenarioBlock? GetCurrentScenarioBlock(SnapshotPoint triggerPoint)
        {
            var parsingResult = gherkinProcessorServices.GetParsingResult(textBuffer);
            if (parsingResult == null)
                return null;

            var triggerLineNumber = triggerPoint.Snapshot.GetLineNumberFromPosition(triggerPoint.Position);
            var scenarioInfo = parsingResult.ScenarioEditorInfos.LastOrDefault(si => si.KeywordLine < triggerLineNumber);
            if (scenarioInfo == null)
                return null;

            for (var lineNumer = triggerLineNumber; lineNumer > scenarioInfo.KeywordLine; lineNumer--)
            {
                StepKeyword? stepKeyword = GetStepKeyword(triggerPoint.Snapshot, lineNumer, parsingResult.LanguageService);

                if (stepKeyword != null)
                {
                    var scenarioBlock = stepKeyword.Value.ToScenarioBlock();
                    if (scenarioBlock != null)
                        return scenarioBlock;
                }
            }

            return ScenarioBlock.Given;
        }

 /// <summary>
 /// Restores saved selection
 /// </summary>
 public override void EndTracking() {
     int position = PositionFromTokens(TextBuffer.CurrentSnapshot, _index, _offset);
     if (position >= 0) {
         PositionAfterChanges = new SnapshotPoint(TextBuffer.CurrentSnapshot, position);
     }
     MoveToAfterChanges(VirtualSpaces);
 }