public static List<Operator<? extends OperatorDesc>> doGetWorksFromPath(Map<Path, List<String>> pathToAliases,
      Map<String, Operator<? extends OperatorDesc>> aliasToWork, Path dir) {
    List<Operator<? extends OperatorDesc>> opList = new ArrayList<Operator<? extends OperatorDesc>>();

    List<String> aliases = doGetAliasesFromPath(pathToAliases, dir);
    for (String alias : aliases) {
      opList.add(aliasToWork.get(alias));
    }
    return opList;
  }
Get the list of operators from the operator tree that are needed for the path
@param pathToAliases  mapping from path to aliases
@param aliasToWork    The operator tree to be invoked for a given alias
@param dir            The path to look for
ql/src/java/org/apache/hadoop/hive/ql/io/HiveFileFormatUtils.java