1 files changed, 47 insertions, 0 deletions
diff --git a/src/library/scala/collection/mutable/ListMap.scala b/src/library/scala/collection/mutable/ListMap.scala
new file mode 100644
index 0000000000..8b8e5d87a6
--- /dev/null
+++ b/src/library/scala/collection/mutable/ListMap.scala
@@ -0,0 +1,47 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id: HashMap.scala 17715 2009-05-12 18:33:22Z odersky $
+
+
+package scala.collection.mutable
+
+import generic._
+
+@serializable
+class ListMap[A, B] extends Map[A, B] with MutableMapTemplate[A, B, ListMap[A, B]] {
+
+
+  override def empty = ListMap.empty[A, B]
+
+  private var elems: List[(A, B)] = List()
+  private var siz: Int = 0
+
+  def get(key: A): Option[B] = elems find (_._1 == key) map (_._2)
+  def elements: Iterator[(A, B)] = elems.elements
+  def += (kv: (A, B)) = { elems = remove(kv._1, elems); elems = kv :: elems; siz += 1; this }
+  def -= (key: A) = { elems = remove(key, elems); this }
+
+  private def remove(key: A, elems: List[(A, B)]): List[(A, B)] =
+    if (elems.isEmpty) elems
+    else if (elems.head._1 == key) { siz -= 1; elems.tail }
+    else elems.head :: remove(key, elems.tail)
+
+  override def clear() = elems = List()
+  override def size: Int = siz
+}
+
+/** This class implements mutable maps using a list.
+ *
+ *  @author  Martin Odersky
+ *  @version 2.8
+ */
+object ListMap extends MutableMapFactory[ListMap] {
+  implicit def builderFactory[A, B]: BuilderFactory[(A, B), ListMap[A, B], Coll] = new MapBuilderFactory[A, B]
+  def empty[A, B]: ListMap[A, B] = new ListMap[A, B]
+}