bject NonEmpty {
  def unapply(s:String): Option[String] = {
    if (s == null) return None
    val t = s.trim
    if (0 == t.length) return None
    return Some(s)
  }
}

object Parsely {

  def buraqParseNumber(in: String): (Long, Int) = in match {
    case NonEmpty(trimmed) =>
      val (sign, startpos) = trimmed.charAt(0) match {
        case '-' => (-1L, 1)
        case '+' => (+1L, 1)
        case _   => (+1L, 0)
      }
      def finished(pos: Int) = { pos == tin.length || !tin.charAt(pos).isDigit }

      def process(acc: Long, pos: Int): (Long, Int) =
        if (finished(pos))
          (acc * sign, pos)
        else {
          val nacc = (acc * 10L) + (trimmed.charAt(pos).toLong - '0'.toLong)
          process(nacc, pos + 1)
        }
      return process(0L, startpos)

    case _ =>
      return (0L,0)
  }
}

spinning <a href="http://erikengbrecht.blogspot.com/2007/05/number-parsing-in-functional-style.html">Erik'code</a>, who spun <a href="http://blog.lostlake.org/index.php?/archives/60-Thinking-functional-Scala-imperative-vs.-functional-code.html">David's code</a>. use nested function, but also uses pattern matching.

Burak (1)

Tags: parsing (1)