1 files changed, 117 insertions, 0 deletions
diff --git a/examples/scala-js/scalalib/overrides/scala/Symbol.scala b/examples/scala-js/scalalib/overrides/scala/Symbol.scala
new file mode 100644
index 0000000..1af9d28
--- /dev/null
+++ b/examples/scala-js/scalalib/overrides/scala/Symbol.scala
@@ -0,0 +1,117 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+package scala
+
+import scala.scalajs.js
+
+/** This class provides a simple way to get unique objects for equal strings.
+ *  Since symbols are interned, they can be compared using reference equality.
+ *  Instances of `Symbol` can be created easily with Scala's built-in quote
+ *  mechanism.
+ *
+ *  For instance, the [[http://scala-lang.org/#_top Scala]] term `'mysym` will
+ *  invoke the constructor of the `Symbol` class in the following way:
+ *  `Symbol("mysym")`.
+ *
+ *  @author  Martin Odersky, Iulian Dragos
+ *  @version 1.8
+ */
+final class Symbol private (val name: String) extends Serializable {
+  /** Converts this symbol to a string.
+   */
+  override def toString(): String = "'" + name
+
+  @throws(classOf[java.io.ObjectStreamException])
+  private def readResolve(): Any = Symbol.apply(name)
+  override def hashCode = name.hashCode()
+  override def equals(other: Any) = this eq other.asInstanceOf[AnyRef]
+}
+
+// Modified to use Scala.js specific cache
+object Symbol extends JSUniquenessCache[Symbol] {
+  override def apply(name: String): Symbol = super.apply(name)
+  protected def valueFromKey(name: String): Symbol = new Symbol(name)
+  protected def keyFromValue(sym: Symbol): Option[String] = Some(sym.name)
+}
+
+private[scala] abstract class JSUniquenessCache[V]
+{
+  private val map = js.Dictionary.empty[js.Any] // V | js.Undefined
+
+  protected def valueFromKey(k: String): V
+  protected def keyFromValue(v: V): Option[String]
+
+  def apply(name: String): V = {
+    val cachedSym = map(name)
+    if (js.isUndefined(cachedSym)) {
+      val sym = valueFromKey(name)
+      map(name) = sym.asInstanceOf[js.Any]
+      sym.asInstanceOf[V]
+    } else {
+      cachedSym.asInstanceOf[V]
+    }
+  }
+
+  def unapply(other: V): Option[String] = keyFromValue(other)
+}
+
+/** This is private so it won't appear in the library API, but
+  * abstracted to offer some hope of reusability.  */
+/* DELETED for Scala.js
+private[scala] abstract class UniquenessCache[K >: js.String, V >: Null]
+{
+
+  import java.lang.ref.WeakReference
+  import java.util.WeakHashMap
+  import java.util.concurrent.locks.ReentrantReadWriteLock
+
+  private val rwl = new ReentrantReadWriteLock()
+  private val rlock = rwl.readLock
+  private val wlock = rwl.writeLock
+  private val map = new WeakHashMap[K, WeakReference[V]]
+
+  protected def valueFromKey(k: K): V
+  protected def keyFromValue(v: V): Option[K]
+
+  def apply(name: K): V = {
+    def cached(): V = {
+      rlock.lock
+      try {
+        val reference = map get name
+        if (reference == null) null
+        else reference.get  // will be null if we were gc-ed
+      }
+      finally rlock.unlock
+    }
+    def updateCache(): V = {
+      wlock.lock
+      try {
+        val res = cached()
+        if (res != null) res
+        else {
+          // If we don't remove the old String key from the map, we can
+          // wind up with one String as the key and a different String as
+          // as the name field in the Symbol, which can lead to surprising
+          // GC behavior and duplicate Symbols. See SI-6706.
+          map remove name
+          val sym = valueFromKey(name)
+          map.put(name, new WeakReference(sym))
+          sym
+        }
+      }
+      finally wlock.unlock
+    }
+
+    val res = cached()
+    if (res == null) updateCache()
+    else res
+  }
+  def unapply(other: V): Option[K] = keyFromValue(other)
+}
+*/