Caesar Codex

CaesarCodex.scala

object CaesarCodex {
 
  class CyclicCharRange(start:Char,end:Char) extends PartialFunction[Char,Int=>Char] {
    val size = end-start+1
  	def isDefinedAt(c:Char) = c>=start && c<=end
  	def apply(c:Char): Int => Char  = { amount =>
  		val rangeAmount = ((amount % size)+size) % size
  		val shiftedValue = (((c-start)+rangeAmount)%size)+start
  		shiftedValue.toChar
  	}
  }
  
  class CharIdentity extends PartialFunction[Char,Int=>Char]  {
    	def isDefinedAt(c:Char) = true
  	def apply(c:Char): Int => Char = x => c
  }
  
  val rangeAZ = new CyclicCharRange('A','Z')
  val rangeaz = new CyclicCharRange('a','z')
  val id = new CharIdentity
  
  def encode(s:String, shift:Int) = {
  	s.map(c => (rangeAZ orElse rangeaz orElse id)(c) (shift))
  }
  
  def decode(s:String, shift:Int) = encode(s,-shift)
  
}