public static boolean isConstant(ExprNodeDesc value) {
    if (value instanceof ExprNodeConstantDesc) {
      return true;
    }
    if (value instanceof ExprNodeGenericFuncDesc) {
      ExprNodeGenericFuncDesc func = (ExprNodeGenericFuncDesc) value;
      if (!FunctionRegistry.isConsistentWithinQuery(func.getGenericUDF())) {
        return false;
      }
      for (ExprNodeDesc child : func.getChildren()) {
        if (!isConstant(child)) {
          return false;
        }
      }
      return true;
    }
    return false;
  }
Get Map of ExprNodeColumnDesc HashCode to ExprNodeColumnDesc.

@param exprDesc
@param hashCodeToColumnDescMap
ql/src/java/org/apache/hadoop/hive/ql/plan/ExprNodeDescUtils.java