public static VectorExpressionWriter genVectorExpressionWritable(VectorExpression vecExpr)
      throws HiveException {
      TypeInfo outputTypeInfo = vecExpr.getOutputTypeInfo();
      ObjectInspector objectInspector =
          TypeInfoUtils.getStandardWritableObjectInspectorFromTypeInfo(
              outputTypeInfo);
      return genVectorExpressionWritable(objectInspector);
    }
Compiles the appropriate vector expression writer based on an expression info (ExprNodeDesc)
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorExpressionWriterFactory.java