code: boolean canBeWalkedInNaturalDocOrderStatic()
    {
  
      if (null != m_firstWalker)
      {
        AxesWalker walker = m_firstWalker;
        int prevAxis = -1;
        boolean prevIsSimpleDownAxis = true;
  
        for(int i = 0; null != walker; i++)
        {
          int axis = walker.getAxis();
          
          if(walker.isDocOrdered())
          {
            boolean isSimpleDownAxis = ((axis == Axis.CHILD)
                                     || (axis == Axis.SELF)
                                     || (axis == Axis.ROOT));
            // Catching the filtered list here is only OK because
            // FilterExprWalker#isDocOrdered() did the right thing.
            if(isSimpleDownAxis || (axis == -1))
              walker = walker.getNextWalker();
            else
            {
              boolean isLastWalker = (null == walker.getNextWalker());
              if(isLastWalker)
              {
                if(walker.isDocOrdered() && (axis == Axis.DESCENDANT || 
                   axis == Axis.DESCENDANTORSELF || axis == Axis.DESCENDANTSFROMROOT
                   || axis == Axis.DESCENDANTSORSELFFROMROOT) || (axis == Axis.ATTRIBUTE))
                  return true;
              }
              return false;
            }
          }
          else
            return false;
        }
        return true;
      }
      return false;
    }
docs: Tell if the nodeset can be walked in doc order, via static analysis.
  
  
  @return true if the nodeset can be walked in doc order, without sorting.