From 2e1aefd1188602c870229d4b6e00d1acfc83036d Mon Sep 17 00:00:00 2001
From: Philipp Haller <hallerp@gmail.com>
Date: Tue, 23 Mar 2010 15:11:05 +0000
Subject: Fixes #3186. Closes #2214.

---
 src/library/scala/Enumeration.scala | 41 +++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/library/scala/Enumeration.scala b/src/library/scala/Enumeration.scala
index 8a708a4615..205cf1cf84 100644
--- a/src/library/scala/Enumeration.scala
+++ b/src/library/scala/Enumeration.scala
@@ -16,6 +16,15 @@ import scala.collection.mutable.{Builder, AddingBuilder, Map, HashMap}
 import scala.collection.immutable.{Set, BitSet}
 import scala.collection.generic.CanBuildFrom
 
+private object Enumeration {
+
+  /* This map is used to cache enumeration instances for
+     resolving enumeration _values_ to equal objects (by-reference)
+     when values are deserialized. */
+  private val emap: Map[Class[_], Enumeration] = new HashMap
+
+}
+
 /** <p>
  *    Defines a finite set of values specific to the enumeration. Typically
  *    these values enumerate all possible forms something can take and provide a
@@ -61,6 +70,21 @@ abstract class Enumeration(initial: Int, names: String*) {
   def this() = this(0, null)
   def this(names: String*) = this(0, names: _*)
 
+  Enumeration.emap.get(getClass) match {
+    case None =>
+      Enumeration.emap += (getClass -> this)
+    case Some(_) =>
+      /* do nothing */
+  }
+
+  private def readResolve(): AnyRef = Enumeration.emap.get(getClass) match {
+    case None =>
+      Enumeration.emap += (getClass -> this)
+      this
+    case Some(existing) =>
+      existing
+  }
+
   /** The name of this enumeration.
    */
   override def toString = {
@@ -192,13 +216,13 @@ abstract class Enumeration(initial: Int, names: String*) {
   /** The type of the enumerated values. */
   @serializable
   @SerialVersionUID(7091335633555234129L)
-  abstract class Value extends Ordered[Enumeration#Value] {
+  abstract class Value extends Ordered[Value] {
     /** the id and bit location of this enumeration value */
     def id: Int
-    override def compare(that: Enumeration#Value): Int = this.id - that.id
+    override def compare(that: Value): Int = this.id - that.id
     override def equals(other: Any): Boolean =
       other match {
-        case that: Enumeration#Value => compare(that) == 0
+        case that: Value => compare(that) == 0
         case _ => false
       }
     override def hashCode: Int = id.hashCode
@@ -211,7 +235,7 @@ abstract class Enumeration(initial: Int, names: String*) {
       if (id >= 32) throw new IllegalArgumentException
       1  << id
     }
-    /** this enumeration value as an <code>Long</code> bit mask.
+    /** this enumeration value as a <code>Long</code> bit mask.
      *  @throws IllegalArgumentException if <code>id</code> is greater than 63
      */
     @deprecated("mask64 will be removed")
@@ -243,9 +267,14 @@ abstract class Enumeration(initial: Int, names: String*) {
     override def toString() =
       if (name eq null) Enumeration.this.nameOf(i)
       else name
-    private def readResolve(): AnyRef =
-      if (vmap ne null) vmap(i)
+    private def readResolve(): AnyRef = {
+      val enum = Enumeration.emap.get(Enumeration.this.getClass) match {
+        case None => Enumeration.this
+        case Some(existing) => existing
+      }
+      if (enum.vmap ne null) enum.vmap(i)
       else this
+    }
   }
 
   /** A class for sets of values
-- 
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