# File lib/rexical/generator.rb, line 231
    def parse_rule(st)
      st.strip!
      return  if st.size == 0 or st[0,1] == '#'
      ss  =  StringScanner.new(st)
      ss.scan(/\s+/)
      rule_state  =  ss.scan(/\:\S+/)
      ss.scan(/\s+/)
      rule_expr  =  ss.scan(/\S+/)
      ss.scan(/\s+/)
      [rule_state, rule_expr, ss.post_match]
    end