{
if (_expr == null) return null;
ExpressionNode result = _expr;
while (result instanceof ExpressionNodeForCellModel) {
final ExpressionNodeForCellModel cellNode = (ExpressionNodeForCellModel) result;
final CellModel cellModel = cellNode.getCellModel();
if (!isInlineable( cellModel )) return result;
result = cellModel.getExpression();
if (null == result) {
result = new ExpressionNodeForConstantValue( cellModel.getConstantValue(), cellModel.getDataType() );
}