ois.add(partObjectInspector);
StructObjectInspector rowWithPartObjectInspector =
ObjectInspectorFactory.getUnionStructObjectInspector(ois);
ExprNodeEvaluator evaluator = ExprNodeEvaluatorFactory.get(expr);
ObjectInspector evaluateResultOI = evaluator.initialize(rowWithPartObjectInspector);
Map<PrimitiveObjectInspector, ExprNodeEvaluator> result =
new HashMap<PrimitiveObjectInspector, ExprNodeEvaluator>();
result.put((PrimitiveObjectInspector)evaluateResultOI, evaluator);
return result;