Roman Numerals

roman.scala

object RomanNumerals {
  import annotation._

    trait Numeral {
      def num:Int
    }

  class RomanNumeral[T<:Numeral](n:Int) extends Number with Ordered[RomanNumeral[Numeral]] {
    private val MAX_ROMAN = 3999
    val num = if(n > 0 && n % MAX_ROMAN != 0) n % MAX_ROMAN else (n % MAX_ROMAN) + MAX_ROMAN

    def compare(that:RomanNumeral[Numeral]) = this.num compare that.num
    def +(number:Number) = new RomanNumeral[Numeral](num + number.intValue)
    def -(number:Number) = new RomanNumeral[Numeral](num - number.intValue)
    def *(number:Number) = new RomanNumeral[Numeral](num * number.intValue)
    def /(number:Number) = new RomanNumeral[Numeral](num / number.intValue)

    def apply[N >: T <: Numeral](rn:NumeralI[N]) = 
      new RomanNumeral[Numeral](rn.num + num) with Numeral

    def apply[N >: T <: Numeral](rn:NumeralV[N]) = 
      new RomanNumeral[NumeralI[Numeral]](rn.num + num) with NumeralV[NumeralI[Numeral]]
    
    def apply[N >: T <: Numeral](rn:NumeralX[N]) = 
      new RomanNumeral[NumeralV[Numeral]](rn.num + num) with NumeralX[NumeralV[Numeral]]

    def apply[N >: T <: Numeral](rn:NumeralL[N]) = 
      new RomanNumeral[NumeralX[Numeral]](rn.num + num) with NumeralL[NumeralX[Numeral]]

    def apply[N >: T <: Numeral](rn:NumeralC[N]) = 
      new RomanNumeral[NumeralL[Numeral]](rn.num + num) with NumeralC[NumeralL[Numeral]]
 
    def apply[N >: T <: Numeral](rn:NumeralD[N]) = 
      new RomanNumeral[NumeralC[Numeral]](rn.num + num) with NumeralD[NumeralC[Numeral]]
    override def intValue = num
    override def byteValue = num.toByte
    override def floatValue = num.toFloat
    override def doubleValue = num.toDouble
    override def longValue = num.toLong
    
    override def equals(that:Any) = 
      that.isInstanceOf[RomanNumeral[Numeral]] && num == that.asInstanceOf[RomanNumeral[Numeral]].num
    override def hashCode = num
    override def toString  = {
      @tailrec
      def innerLoop(int:Int, count:Int, 
                    sb:StringBuilder, 
                    rPair:(Int,String)):(StringBuilder, Int, Int) = {
        if(int > 0 && count > 0 
           && rPair._1 > 0 
           && (int - rPair._1) >= 0) {
          if(count > int) {
            innerLoop(int, count - rPair._1, sb, rPair)
          } else {
            sb.append(rPair._2)
            innerLoop(int - rPair._1, count, sb, rPair)
          }
           } else {
             (sb, int, rPair._1)
           }
        }
   
      val listOfPairs:List[(Int,String)] = 
        (1000, "M")::(900, "CM")::
        (500, "D")::(400, "CD")::
        (100, "C")::(90, "XC")::
        (50, "L")::(40, "XL")::
        (10, "X")::(9, "IX")::
        (5,"V")::(4, "IV")::
        (1,"I")::Nil

      listOfPairs.foldLeft((new StringBuilder(), num, 3999))(
        (sbNumCounter,romanNumPair) => {
          val (sb, int, counter) = sbNumCounter
          innerLoop(int, counter, sb, romanNumPair) 
        })._1 toString
    }
  }

  object RomanNumeral {
    def apply[T<:Numeral](int:Int) = new RomanNumeral[T](int)
    def unapply(rn:RomanNumeral[Numeral]) = Some(rn.num)
  }

  trait NumeralI[N<:Numeral] extends Numeral
  trait NumeralV[N<:Numeral] extends NumeralI[N] {
    def I = new RomanNumeral[Numeral](1 + this.num) with Numeral
    def II = new RomanNumeral[Numeral](2 + this.num) with Numeral
    def III = new RomanNumeral[Numeral](3 + this.num) with Numeral
  }
  
  trait NumeralX[N<:Numeral] extends NumeralV[N] {
    def IV = new RomanNumeral[Numeral](4 + this.num) with Numeral
    def V = new RomanNumeral[NumeralI[Numeral]](5 + this.num) with NumeralV[NumeralI[Numeral]]
    def IX = new RomanNumeral[Numeral](9 + this.num) with Numeral
  }

  trait NumeralL[N<:Numeral] extends NumeralX[N] {
    def X = new RomanNumeral[NumeralV[Numeral]](10 + this.num) with NumeralX[NumeralV[Numeral]]
    def XX = new RomanNumeral[NumeralV[Numeral]](20 + this.num) with NumeralX[NumeralV[Numeral]]
    def XXX = new RomanNumeral[NumeralV[Numeral]](30 + this.num) with NumeralX[NumeralV[Numeral]]
  }

  trait NumeralC[N<:Numeral] extends NumeralL[N] {
    def XL = new RomanNumeral[NumeralV[Numeral]](40 + this.num) with NumeralX[NumeralV[Numeral]]
    def L = new RomanNumeral[NumeralX[Numeral]](50 + this.num) with NumeralL[NumeralX[Numeral]]
    def XC = new RomanNumeral[NumeralV[Numeral]](90 + this.num) with NumeralX[NumeralV[Numeral]]
  }

  trait NumeralD[N<:Numeral] extends NumeralC[N] {
    def C = new RomanNumeral[NumeralL[Numeral]](100 + this.num) with NumeralC[NumeralL[Numeral]]
    def CC = new RomanNumeral[NumeralL[Numeral]](200 + this.num)  with NumeralC[NumeralL[Numeral]]
    def CCC = new RomanNumeral[NumeralL[Numeral]](300 + this.num)   with NumeralC[NumeralL[Numeral]]
  }

  trait NumeralM[N<:Numeral] extends NumeralD[N] {
    def CD = new RomanNumeral[NumeralL[Numeral]](400 + this.num) with NumeralC[NumeralL[Numeral]]
    def D = new  RomanNumeral[NumeralC[Numeral]](500 + this.num) with NumeralD[NumeralC[Numeral]]
    def CM = new RomanNumeral[NumeralL[Numeral]](900 + this.num) with NumeralC[NumeralL[Numeral]]
  }

  val I = new RomanNumeral[NumeralI[Numeral]](1) with NumeralI[Numeral]
  val II = new RomanNumeral[NumeralI[Numeral]](2) with NumeralI[Numeral]
  val III = new RomanNumeral[NumeralI[Numeral]](3) with NumeralI[Numeral]
  val IV = new RomanNumeral[NumeralI[Numeral]](4) with NumeralI[Numeral]
  val V = new RomanNumeral[NumeralI[Numeral]](5) with NumeralV[NumeralV[Numeral]]
  val IX = new RomanNumeral[NumeralI[Numeral]](9) with NumeralI[Numeral]
  val X = new RomanNumeral[NumeralV[Numeral]](10) with NumeralX[NumeralX[Numeral]]
  val XX = new RomanNumeral[NumeralV[Numeral]](20) with NumeralX[NumeralX[Numeral]]
  val XXX = new RomanNumeral[NumeralV[Numeral]](30) with NumeralX[NumeralX[Numeral]]
  val XL = new RomanNumeral[NumeralV[Numeral]](40) with NumeralX[NumeralX[Numeral]]
  val L = new RomanNumeral[NumeralX[Numeral]](50) with NumeralL[NumeralL[Numeral]] 
  val XC = new RomanNumeral[NumeralV[Numeral]](90) with NumeralX[NumeralX[Numeral]]
  val C = new RomanNumeral[NumeralL[Numeral]](100) with NumeralC[NumeralC[Numeral]]
  val CC = new RomanNumeral[NumeralL[Numeral]](200)  with NumeralC[NumeralC[Numeral]] 
  val CCC = new RomanNumeral[NumeralL[Numeral]](300)   with NumeralC[NumeralC[Numeral]] 
  val CD = new RomanNumeral[NumeralL[Numeral]](400)  with NumeralC[NumeralC[Numeral]]
  val D = new  RomanNumeral[NumeralC[Numeral]](500)  with NumeralD[NumeralD[Numeral]]
  val CM = new RomanNumeral[NumeralL[Numeral]](900) with NumeralC[NumeralC[Numeral]] 
  val M = new RomanNumeral[NumeralD[Numeral]](1000) with NumeralM[NumeralM[Numeral]]
  val MM = new RomanNumeral[NumeralD[Numeral]](2000) with NumeralM[NumeralM[Numeral]]
  val MMM = new RomanNumeral[NumeralD[Numeral]](3000) with NumeralM[NumeralM[Numeral]]
  implicit def num2RomanNumeral(n:Number):RomanNumeral[Numeral] = 
    new RomanNumeral[Numeral](n.intValue)
}