Cache.scala (this time public)

Cache.scala

asdf//In reality, this is all we need, no?
//See https://github.com/jsr107/jsr107spec
trait Cache[Key,Value]{
  def get(key: Key): Option[Key]
  def getOrElse(key: Key, value: Value) = get(key) getOrElse value
  def set(key: Key, value: Value): Value
  def contains(key: Key): Boolean
  def replace(key: Key, value: Value): Option[Value] ={
    val previous = get(key)
    set(key, value)
    previous
  }
  def invalidate(key: Key): Value
  protected def default(key: Key): Value
  
  def apply(key: Key) = get(key) orElse default(key)
  
  def toString() = "Cache(%s)" format this
}
 
trait Memoize[T,R](f: T => R, cache: Cache[T,R]) extends (T => R){
  def apply(arg: T) = cache get (arg) getOrElse (cache set (arg, f(arg)))
  
  def toString() = "<memoize>"
}