DirtyFlash.scala

import org.scalatra.util.MutableMapWithIndifferentAccess
import scala.collection.mutable.{ Map => MMap }

/**
 * Provides a Rails/Scalatra like map that sits in the session
 * and destroys values after the request they were accessed in has returned
 *
 * @author paulitex
 *
 */
class Flash extends MutableMapWithIndifferentAccess[Any] {

    private val map = MMap[String, Any]()
    private var dirtyKeys: Set[String] = Set()

    def -=(key: String) = {
        map -= key
        this
    }

    def +=(kv: (String, Any)) = {
        map += kv
        this
    }

    def iterator = map.iterator

    def get(key: String) = {
        dirtyKeys += key
        map.get(key)
    }

    def sweep() {
        dirtyKeys.foreach(map -= _)
        dirtyKeys = Set.empty
        this
    }
}