protected static ObjectInspector[] initEvaluators(ExprNodeEvaluator<?>[] evals,
      int start, int length,
      ObjectInspector rowInspector) throws HiveException {
    ObjectInspector[] result = new ObjectInspector[length];
    for (int i = 0; i < length; i++) {
      result[i] = evals[start + i].initialize(rowInspector);
    }
    return result;
  }
Initialize an array of ExprNodeEvaluator from start, for specified length
and return the result ObjectInspectors.
ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java