Collections refactoring.

1 files changed, 48 insertions, 0 deletions

diff --git a/src/library/scala/collection/mutable/DoubleLinkedListLike.scala b/src/library/scala/collection/mutable/DoubleLinkedListLike.scala
new file mode 100644
index 0000000000..637d67396b
--- /dev/null
+++ b/src/library/scala/collection/mutable/DoubleLinkedListLike.scala
@@ -0,0 +1,48 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id$
+
+
+package scala.collection
+package mutable
+
+/** This extensible class may be used as a basis for implementing double
+ *  linked lists. Type variable <code>A</code> refers to the element type
+ *  of the list, type variable <code>This</code> is used to model self
+ *  types of linked lists.
+ *
+ *  @author  Matthias Zenger
+ *  @version 1.0, 08/07/2003
+ */
+trait DoubleLinkedListLike[A, This >: Null <: LinearSequence[A] with DoubleLinkedListLike[A, This]] extends LinkedListLike[A, This] { self =>
+
+  var prev: This = _
+
+  override def append(that: This): Unit =
+    if (next eq null) {
+      next = that
+      if (that ne null) that.prev = repr
+    } else
+      next.append(that)
+
+  override def insert(that: This): Unit = if (that ne null) {
+    that.append(next)
+    next = that
+    that.prev = repr
+  }
+
+  def remove() {
+    if (next ne null)
+      next.prev = prev
+    if (prev ne null)
+      prev.next = next
+    prev = null
+    next = null
+  }
+}