protected PrimitiveGrouping primitiveGroupOf(ObjectInspector oi) {
    if (oi instanceof PrimitiveObjectInspector) {
      PrimitiveCategory category = ((PrimitiveObjectInspector) oi).getPrimitiveCategory();
      PrimitiveGrouping group = PrimitiveObjectInspectorUtils.getPrimitiveGrouping(category);
      return group;
    } else {
      return null;
    }
  }
Returns whether the operator can handle operands with the specified category.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFBaseCompare.java