public static SearchArgument createFromConf(Configuration conf) {
    String sargString;
    if ((sargString = conf.get(TableScanDesc.FILTER_EXPR_CONF_STR)) != null) {
      return getSearchArgumentFromExpression(conf, sargString);
    } else if ((sargString = conf.get(SARG_PUSHDOWN)) != null) {
      return getSearchArgumentFromString(conf, sargString);
    }
    return null;
  }
Do the recursive parse of the Hive ExprNodeDesc into our ExpressionTree.
@param expression the Hive ExprNodeDesc
ql/src/java/org/apache/hadoop/hive/ql/io/sarg/ConvertAstToSearchArg.java