1 files changed, 43 insertions, 0 deletions
diff --git a/src/library/scala/xml/persistent/SetStorage.scala b/src/library/scala/xml/persistent/SetStorage.scala
new file mode 100644
index 0000000000..1391f1f76e
--- /dev/null
+++ b/src/library/scala/xml/persistent/SetStorage.scala
@@ -0,0 +1,43 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2007, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id$
+
+package scala.xml.persistent
+
+import scala.collection.mutable
+import java.io.File
+
+/** A persistent store with set semantics. This class allows to add and remove
+ *  trees, but never contains two structurally equal trees.
+ *
+ *  @author Burak Emir
+ */
+class SetStorage(file: File) extends CachedFileStorage(file) {
+
+  private var theSet: mutable.HashSet[Node] = new mutable.HashSet[Node]
+
+  // initialize
+
+  {
+    val it = super.initialNodes
+    dirty = it.hasNext
+    for(val x <- it) {
+      theSet += x;
+    }
+  }
+
+  /* forwarding methods to hashset*/
+
+  def += (e: Node): Unit = synchronized { this.dirty = true; theSet += e }
+
+  def -= (e: Node): Unit = synchronized { this.dirty = true; theSet -= e }
+
+  def nodes = synchronized { theSet.elements }
+
+}