private void resetRootInformation() {
    // Reset the previously stored rootNode string
    if (rootNode != null) {
      rootNode.astStr = null;
      rootNode.isValidASTStr = false;
    }
  }
Tag this ASTNode with information about the object from which this node
originated.
parser/src/java/org/apache/hadoop/hive/ql/parse/ASTNode.java