text: public ValueEval Evaluate(String sheetName, int rowIndex, int columnIndex){IEvaluationCell cell = _sewb.GetEvaluationCell(sheetName, rowIndex, columnIndex);switch (cell.CellType){case CellType.Boolean:return BoolEval.ValueOf(cell.BooleanCellValue);case CellType.Error:return ErrorEval.ValueOf(cell.ErrorCellValue);case CellType.Formula:return _evaluator.Evaluate(cell);case CellType.Numeric:return new NumberEval(cell.NumericCellValue);case CellType.String:return new StringEval(cell.StringCellValue);case CellType.Blank:return null;}throw new InvalidOperationException("Bad cell type (" + cell.CellType + ")");}