public static VectorExpressionWriter[] getExpressionWriters(List<ExprNodeDesc> nodesDesc)
      throws HiveException {
    VectorExpressionWriter[] writers = new VectorExpressionWriter[nodesDesc.size()];
    for(int i=0; i<writers.length; ++i) {
      ExprNodeDesc nodeDesc = nodesDesc.get(i);
      writers[i] = genVectorExpressionWritable(nodeDesc);
    }
    return writers;
  }
Helper function to create an array of writers from a list of expression descriptors.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorExpressionWriterFactory.java