1 files changed, 52 insertions, 0 deletions
diff --git a/src/compiler/scala/reflect/runtime/TwoWayCache.scala b/src/compiler/scala/reflect/runtime/TwoWayCache.scala
new file mode 100644
index 0000000000..c7bfb3435d
--- /dev/null
+++ b/src/compiler/scala/reflect/runtime/TwoWayCache.scala
@@ -0,0 +1,52 @@
+package scala.reflect
+package runtime
+
+/** A cache that maintains a bijection between Java reflection type `J`
+ *  and Scala reflection type `S`.
+ */
+import collection.mutable.HashMap
+
+private[runtime] class TwoWayCache[J, S] {
+
+  private val toScalaMap = new HashMap[J, S]
+  private val toJavaMap = new HashMap[S, J]
+
+  def enter(j: J, s: S) = synchronized {
+    // debugInfo("cached: "+j+"/"+s)
+    toScalaMap(j) = s
+    toJavaMap(s) = j
+  }
+
+  def toScala(key: J)(body: => S): S = synchronized {
+    toScalaMap get key match {
+      case Some(v) =>
+        v
+      case none =>
+        val result = body
+        enter(key, result)
+        result
+    }
+  }
+
+  def toJava(key: S)(body: => J): J = synchronized {
+    toJavaMap get key match {
+      case Some(v) =>
+        v
+      case none =>
+        val result = body
+        enter(result, key)
+        result
+    }
+  }
+
+  def toJavaOption(key: S)(body: => Option[J]): Option[J] = synchronized {
+    toJavaMap get key match {
+      case None =>
+        val result = body
+        for (value <- result) enter(value, key)
+        result
+      case some => some
+    }
+  }
+}
+