Priority queue reverse is undefined - overriden...

Priority queue reverse is undefined - overriden to throw an exception.
Reverse iterator seems to have sense - it is overriden and is defined, and some methods in SeqLike are implemented in terms of it.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/library/scala/collection/mutable/PriorityQueue.scala b/src/library/scala/collection/mutable/PriorityQueue.scala
index d6b5d12749..54505dbdf6 100644
--- a/src/library/scala/collection/mutable/PriorityQueue.scala
+++ b/src/library/scala/collection/mutable/PriorityQueue.scala
@@ -202,6 +202,20 @@ class PriorityQueue[A](implicit ord: Ordering[A])
     }
   }
 
+  override def reverse = throw new UnsupportedOperationException("Priority queue cannot be reversed.")
+
+  override def reverseIterator = new Iterator[A] {
+    val arr = new Array[Any](size)
+    iterator.copyToArray(arr)
+    var i = arr.size - 1
+    def hasNext: Boolean = i >= 0
+    def next(): A = {
+      val curr = arr(i)
+      i -= 1
+      curr.asInstanceOf[A]
+    }
+  }
+
   /** The hashCode method always yields an error, since it is not
    *  safe to use mutable queues as keys in hash tables.
    *