code: public void setRoot(int context, Object environment)
    {
      super.setRoot(context, environment);
  
      try
      {
        if (null != m_exprs)
        {
          int n = m_exprs.length;
          DTMIterator newIters[] = new DTMIterator[n];
    
          for (int i = 0; i < n; i++)
          {
            DTMIterator iter = m_exprs[i].asIterator(m_execContext, context);
            newIters[i] = iter;
            iter.nextNode();
          }
          m_iterators = newIters;
        }
      }
      catch(Exception e)
      {
        throw new org.apache.xml.utils.WrappedRuntimeException(e);
      }
    }
docs: Initialize the context values for this expression
  after it is cloned.
  
  @param context The XPath runtime context for this
  transformation.