---

yaml
---
r: 81149
b: refs/heads/snap-stage3
c: 57757a8
h: refs/heads/master
i:
  81147: 2669bc6
v: v3

Author: blake2-ppc

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: 4c6bf4872012c010f84dc7fa2cdfe87522533f89
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 5adfa1038787cb042ca5bbe634082201d71a3b72
+refs/heads/snap-stage3: 57757a8051101eb64eb7a330d7c673422e06a57b
 refs/heads/try: 70152ff55722878cde684ee6462c14c65f2c4729
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/src/libextra/ringbuf.rs

@@ -143,6 +143,19 @@ impl<T> RingBuf<T> {
         }
     }
 
+    /// Swap elements at indices `i` and `j`
+    ///
+    /// `i` and `j` may be equal.
+    ///
+    /// Fails if there is no element with the given index
+    pub fn swap(&mut self, i: uint, j: uint) {
+        assert!(i < self.len());
+        assert!(j < self.len());
+        let ri = self.raw_index(i);
+        let rj = self.raw_index(j);
+        self.elts.swap(ri, rj);
+    }
+
     /// Return index in underlying vec for a given logical element index
     fn raw_index(&self, idx: uint) -> uint {
         raw_index(self.lo, self.elts.len(), idx)
@@ -604,6 +617,14 @@ mod tests {
         assert_eq!(d.elts.capacity(), 64);
     }
 
+    #[test]
+    fn test_swap() {
+        let mut d: RingBuf<int> = range(0, 5).collect();
+        d.pop_front();
+        d.swap(0, 3);
+        assert_eq!(d.iter().map(|&x|x).collect::<~[int]>(), ~[4, 2, 3, 1]);
+    }
+
     #[test]
     fn test_iter() {
         let mut d = RingBuf::new();