/// <summary> /// Handles non-trivial changes like changes that delete elements, /// change identifier names, introducing new braces: changes /// that cannot be handled without background parse. /// </summary> private void ProcessComplexChange(TextChangeContext context) { // Cancel background parse if it is running Cancel(); var c = context.PendingChanges; try { // Get write lock since there may be concurrent readers // of the tree. Note that there are no concurrent writers // since changes can only come from a background parser // and are always applied from the main thread. _editorTree.AcquireWriteLock(); int start, oldLength, newLength; if (Changes.FullParseRequired) { // When full parse is required, change is like replace the entire file start = 0; oldLength = c.OldTextProvider.Length; newLength = c.NewTextProvider.Length; // Remove damaged elements if any and reflect text change. // the tree remains usable outside of the damaged scope. _editorTree.InvalidateInRange(c.OldRange); _editorTree.NotifyTextChange(c.Start, c.OldLength, c.NewLength); } else { start = c.Start; oldLength = c.OldLength; newLength = c.NewLength; DeleteAndShiftElements(context); Debug.Assert(_editorTree.AstRoot.Children.Count > 0); } var ttc = new TreeTextChange(start, oldLength, newLength, _editorTree.BufferSnapshot, EditorBuffer.CurrentSnapshot); Changes.Combine(ttc); Changes.Version = EditorBuffer?.CurrentSnapshot?.Version ?? 1; _editorTree.BufferSnapshot = EditorBuffer.CurrentSnapshot; } finally { // Lock must be released before firing events otherwise we may hang _editorTree.ReleaseWriteLock(); } _editorTree.FireOnUpdateCompleted(TreeUpdateType.NodesRemoved); }