Implement enum desugaring

2 files changed, 26 insertions, 0 deletions

diff --git a/library/src/scala/Enum.scala b/library/src/scala/Enum.scala
new file mode 100644
index 000000000..7d2eefb3d
--- /dev/null
+++ b/library/src/scala/Enum.scala
@@ -0,0 +1,8 @@
+package scala
+
+/** A base trait of all enum classes */
+trait Enum {
+
+  /** A number uniquely identifying a case of an enum */
+  def enumTag: Int
+}
diff --git a/library/src/scala/runtime/EnumValues.scala b/library/src/scala/runtime/EnumValues.scala
new file mode 100644
index 000000000..6d2e56cf3
--- /dev/null
+++ b/library/src/scala/runtime/EnumValues.scala
@@ -0,0 +1,18 @@
+package scala.runtime
+
+import scala.collection.immutable.Seq
+import scala.collection.mutable.ResizableArray
+
+class EnumValues[E <: Enum] extends ResizableArray[E] {
+  private var valuesCache: List[E] = Nil
+  def register(v: E) = {
+    ensureSize(v.enumTag + 1)
+    size0 = size0 max (v.enumTag + 1)
+    array(v.enumTag) = v
+    valuesCache = null
+  }
+  def values: Seq[E] = {
+    if (valuesCache == null) valuesCache = array.filter(_ != null).toList.asInstanceOf[scala.List[E]]
+    valuesCache
+  }
+}