Add mutable tree sets to the standard library.

This implementation is based on AVL trees.
The current implementation is contributed by Lucien Pereira.

Fixes #4147.

1 files changed, 49 insertions, 0 deletions

diff --git a/src/library/scala/collection/mutable/SortedSet.scala b/src/library/scala/collection/mutable/SortedSet.scala
new file mode 100644
index 0000000000..d87fc0b4a2
--- /dev/null
+++ b/src/library/scala/collection/mutable/SortedSet.scala
@@ -0,0 +1,49 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2011, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+package scala.collection
+package mutable
+
+import generic._
+
+/**
+ * Base trait for mutable sorted set.
+ * 
+ * @define Coll mutable.SortedSet
+ * @define coll mutable sorted set
+ *
+ * @author Lucien Pereira
+ * 
+ */
+trait SortedSet[A] extends collection.SortedSet[A] with collection.SortedSetLike[A,SortedSet[A]]
+  with mutable.Set[A] with mutable.SetLike[A, SortedSet[A]] {
+
+  /** Needs to be overridden in subclasses. */
+  override def empty: SortedSet[A] = SortedSet.empty[A]
+
+}
+
+/**
+ * A template for mutable sorted set companion objects.
+ *
+ * @define Coll mutable.SortedSet
+ * @define coll mutable sorted set
+ * @define factoryInfo
+ *   This object provides a set of operations needed to create sorted sets of type mutable.SortedSet.
+ * @define sortedSetCanBuildFromInfo
+ *   Standard `CanBuildFrom` instance for sorted sets.
+ *
+ * @author Lucien Pereira
+ * 
+ */
+object SortedSet extends MutableSortedSetFactory[SortedSet] {
+  implicit def canBuildFrom[A](implicit ord: Ordering[A]): CanBuildFrom[Coll, A, SortedSet[A]] = new SortedSetCanBuildFrom[A]
+  
+  def empty[A](implicit ord: Ordering[A]): SortedSet[A] = TreeSet.empty[A]
+  
+}