问在scala中查找未关闭的字符串(词法分析)

EN

    class SimpleLexer extends StdLexical {
      import scala.util.parsing.input.CharArrayReader.EofCh

       def regex(r: Regex): Parser[String] = new Parser[String] {
         def apply(in: Input) = {
           val source = in.source
           val offset = in.offset
           (r findPrefixMatchOf (source.subSequence(offset, source.length))) match {
               case Some(matched) =>
                  Success(source.subSequence(offset, offset + matched.end).toString,
                  in.drop(matched.end))
              case None =>
                  Failure("string matching regex `" + r + "' expected but `" + in.first + "' found", in.drop(0))
      }
    }
  }


         override def token: Parser[Token] = {
         // Adapted from StdLexical
           (    
            '\"' ~ rep( chrExcept('\"', '\n','\t','\b','\f','\r', EofCh) ) ~ '\"' ^^ { case '\"' ~            chars ~ '\"' => StringLit(chars mkString "") } 
            |'\"' ~> failure("Unclosed string: "+"??") // I want produce fail string                                
            |EofCh ^^^ EOF
            |delim

       )
        }

       override def whitespace: Parser[Any] = rep(
         whitespaceChar
         | '/' ~ '*' ~ comment
         | '/' ~ '*' ~> failure("unclosed comment"))

       override protected def comment: Parser[Any] = (
         '*' ~ '/' ^^ { case _ => ' ' }
         | chrExcept(EofCh) ~ comment)


}