diff options
| -rw-r--r-- | library/alloc/src/collections/vec_deque/mod.rs | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs index 712f38a76c0..08b1828ff00 100644 --- a/library/alloc/src/collections/vec_deque/mod.rs +++ b/library/alloc/src/collections/vec_deque/mod.rs @@ -1312,6 +1312,8 @@ impl<T, A: Allocator> VecDeque<T, A> { /// /// If [`make_contiguous`] was previously called, all elements of the /// deque will be in the first slice and the second slice will be empty. + /// Otherwise, the exact split point depends on implementation details + /// and is not guaranteed. /// /// [`make_contiguous`]: VecDeque::make_contiguous /// @@ -1326,12 +1328,18 @@ impl<T, A: Allocator> VecDeque<T, A> { /// deque.push_back(1); /// deque.push_back(2); /// - /// assert_eq!(deque.as_slices(), (&[0, 1, 2][..], &[][..])); + /// let expected = [0, 1, 2]; + /// let (front, back) = deque.as_slices(); + /// assert_eq!(&expected[..front.len()], front); + /// assert_eq!(&expected[front.len()..], back); /// /// deque.push_front(10); /// deque.push_front(9); /// - /// assert_eq!(deque.as_slices(), (&[9, 10][..], &[0, 1, 2][..])); + /// let expected = [9, 10, 0, 1, 2]; + /// let (front, back) = deque.as_slices(); + /// assert_eq!(&expected[..front.len()], front); + /// assert_eq!(&expected[front.len()..], back); /// ``` #[inline] #[stable(feature = "deque_extras_15", since = "1.5.0")] @@ -1347,6 +1355,8 @@ impl<T, A: Allocator> VecDeque<T, A> { /// /// If [`make_contiguous`] was previously called, all elements of the /// deque will be in the first slice and the second slice will be empty. + /// Otherwise, the exact split point depends on implementation details + /// and is not guaranteed. /// /// [`make_contiguous`]: VecDeque::make_contiguous /// @@ -1363,9 +1373,22 @@ impl<T, A: Allocator> VecDeque<T, A> { /// deque.push_front(10); /// deque.push_front(9); /// - /// deque.as_mut_slices().0[0] = 42; - /// deque.as_mut_slices().1[0] = 24; - /// assert_eq!(deque.as_slices(), (&[42, 10][..], &[24, 1][..])); + /// // Since the split point is not guaranteed, we may need to update + /// // either slice. + /// let mut update_nth = |index: usize, val: u32| { + /// let (front, back) = deque.as_mut_slices(); + /// if index > front.len() - 1 { + /// back[index - front.len()] = val; + /// } else { + /// front[index] = val; + /// } + /// }; + /// + /// update_nth(0, 42); + /// update_nth(2, 24); + /// + /// let v: Vec<_> = deque.into(); + /// assert_eq!(v, [42, 10, 24, 1]); /// ``` #[inline] #[stable(feature = "deque_extras_15", since = "1.5.0")] |