Make BinaryHeap's Items iterator implement DoubleEnded and ExactSize

1 files changed, 17 insertions, 0 deletions

diff --git a/src/libcollections/binary_heap.rs b/src/libcollections/binary_heap.rs
index 8efc4cd50c1..4abe555b0ea 100644
--- a/src/libcollections/binary_heap.rs
+++ b/src/libcollections/binary_heap.rs
@@ -567,6 +567,13 @@ impl<'a, T> Iterator<&'a T> for Items<'a, T> {
     fn size_hint(&self) -> (uint, Option<uint>) { self.iter.size_hint() }
 }
 
+impl<'a, T> DoubleEndedIterator<&'a T> for Items<'a, T> {
+    #[inline]
+    fn next_back(&mut self) -> Option<(&'a T)> { self.iter.next_back() }
+}
+
+impl<'a, T> ExactSize<&'a T> for Items<'a, T> {}
+
 /// An iterator that moves out of a `BinaryHeap`.
 pub struct MoveItems<T> {
     iter: vec::MoveItems<T>,
@@ -626,6 +633,16 @@ mod tests {
     }
 
     #[test]
+    fn test_iterator_reverse() {
+        let data = vec!(5i, 9, 3);
+        let iterout = vec!(3i, 5, 9);
+        let pq = BinaryHeap::from_vec(data);
+
+        let v: Vec<int> = pq.iter().rev().map(|&x| x).collect();
+        assert_eq!(v, iterout);
+    }
+
+    #[test]
     fn test_move_iter() {
         let data = vec!(5i, 9, 3);
         let iterout = vec!(9i, 5, 3);