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package scala
package reflect
package runtime
import scala.collection.mutable.WeakHashMap
import java.lang.ref.WeakReference
/** A cache that maintains a bijection between Java reflection type `J`
* and Scala reflection type `S`.
*
* The cache is two-way weak (i.e. is powered by weak references),
* so that neither Java artifacts prevent Scala artifacts from being garbage collected,
* nor the other way around.
*/
private[runtime] class TwoWayCache[J, S] {
private val toScalaMap = new WeakHashMap[J, WeakReference[S]]
private val toJavaMap = new WeakHashMap[S, WeakReference[J]]
def enter(j: J, s: S) = synchronized {
// debugInfo("cached: "+j+"/"+s)
toScalaMap(j) = new WeakReference(s)
toJavaMap(s) = new WeakReference(j)
}
private object SomeRef {
def unapply[T](optRef: Option[WeakReference[T]]): Option[T] =
if (optRef.nonEmpty) {
Option(optRef.get.get)
} else None
}
def toScala(key: J)(body: => S): S = synchronized {
toScalaMap get key match {
case SomeRef(v) =>
v
case _ =>
val result = body
enter(key, result)
result
}
}
def toJava(key: S)(body: => J): J = synchronized {
toJavaMap get key match {
case SomeRef(v) =>
v
case _ =>
val result = body
enter(result, key)
result
}
}
}
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