FastColoredTextBoxNS.ReplaceMultipleTextCommand.Undo C# (CSharp) Method

        public override void Undo()
        {
            var tb = ts.CurrentTB;

            ts.OnTextChanging();

            tb.Selection.BeginUpdate();
            for (int i = 0; i < ranges.Count; i++)
            {
                tb.Selection.Start = ranges[i].ReplacedRange.Start;
                for (int j = 0; j < ranges[i].ReplaceText.Length; j++)
                    tb.Selection.GoRight(true);
                ClearSelectedCommand.ClearSelected(ts);
                var prevTextIndex = ranges.Count - 1 - i;
                InsertTextCommand.InsertText(prevText[prevTextIndex], ts);
                ts.OnTextChanged(ranges[i].ReplacedRange.Start.iLine, ranges[i].ReplacedRange.Start.iLine);
            }
            tb.Selection.EndUpdate();

            ts.NeedRecalc(new TextSource.TextChangedEventArgs(0, 1));
        }