code: private final boolean lookbehindHasToken(int n)
    {
  
      boolean hasToken;
  
      if ((m_queueMark - n) > 0)
      {
        String lookbehind = (String) m_ops.m_tokenQueue.elementAt(m_queueMark - (n - 1));
        char c0 = (lookbehind == null) ? '|' : lookbehind.charAt(0);
  
        hasToken = (c0 == '|') ? false : true;
      }
      else
      {
        hasToken = false;
      }
  
      return hasToken;
    }
docs: look behind the current token in order to
  see if there is a useable token.
  
  @param n number of tokens to look behind.  Must be
  greater than 1.  Note that the look behind terminates
  at either the beginning of the string or on a '|'
  character.  Because of this, this method should only
  be used for pattern matching.
  
  @return true if look behind has a token, false otherwise.