diff options
Diffstat (limited to 'src/liballoc/slice.rs')
| -rw-r--r-- | src/liballoc/slice.rs | 99 |
1 files changed, 64 insertions, 35 deletions
diff --git a/src/liballoc/slice.rs b/src/liballoc/slice.rs index 18bb13d847a..06913de9fd8 100644 --- a/src/liballoc/slice.rs +++ b/src/liballoc/slice.rs @@ -1360,24 +1360,61 @@ impl<T> [T] { core_slice::SliceExt::sort_unstable_by_key(self, f); } - /// Permutes the slice in-place such that `self[mid..]` moves to the - /// beginning of the slice while `self[..mid]` moves to the end of the - /// slice. Equivalently, rotates the slice `mid` places to the left - /// or `k = self.len() - mid` places to the right. + /// Rotates the slice in-place such that the first `mid` elements of the + /// slice move to the end while the last `self.len() - mid` elements move to + /// the front. After calling `rotate_left`, the element previously at index + /// `mid` will become the first element in the slice. /// - /// This is a "k-rotation", a permutation in which item `i` moves to - /// position `i + k`, modulo the length of the slice. See _Elements - /// of Programming_ [ยง10.4][eop]. + /// # Panics + /// + /// This function will panic if `mid` is greater than the length of the + /// slice. Note that `mid == self.len()` does _not_ panic and is a no-op + /// rotation. + /// + /// # Complexity + /// + /// Takes linear (in `self.len()`) time. + /// + /// # Examples /// - /// Rotation by `mid` and rotation by `k` are inverse operations. + /// ``` + /// #![feature(slice_rotate)] /// - /// [eop]: https://books.google.com/books?id=CO9ULZGINlsC&pg=PA178&q=k-rotation + /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; + /// a.rotate_left(2); + /// assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']); + /// ``` + /// + /// Rotating a subslice: + /// + /// ``` + /// #![feature(slice_rotate)] + /// + /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; + /// a[1..5].rotate_left(1); + /// assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']); + /// ``` + #[unstable(feature = "slice_rotate", issue = "41891")] + pub fn rotate_left(&mut self, mid: usize) { + core_slice::SliceExt::rotate_left(self, mid); + } + + #[unstable(feature = "slice_rotate", issue = "41891")] + #[rustc_deprecated(since = "", reason = "renamed to `rotate_left`")] + pub fn rotate(&mut self, mid: usize) { + core_slice::SliceExt::rotate_left(self, mid); + } + + /// Rotates the slice in-place such that the first `self.len() - k` + /// elements of the slice move to the end while the last `k` elements move + /// to the front. After calling `rotate_right`, the element previously at + /// index `self.len() - k` will become the first element in the slice. /// /// # Panics /// - /// This function will panic if `mid` is greater than the length of the - /// slice. (Note that `mid == self.len()` does _not_ panic; it's a nop - /// rotation with `k == 0`, the inverse of a rotation with `mid == 0`.) + /// This function will panic if `k` is greater than the length of the + /// slice. Note that `k == self.len()` does _not_ panic and is a no-op + /// rotation. /// /// # Complexity /// @@ -1388,31 +1425,23 @@ impl<T> [T] { /// ``` /// #![feature(slice_rotate)] /// - /// let mut a = [1, 2, 3, 4, 5, 6, 7]; - /// let mid = 2; - /// a.rotate(mid); - /// assert_eq!(&a, &[3, 4, 5, 6, 7, 1, 2]); - /// let k = a.len() - mid; - /// a.rotate(k); - /// assert_eq!(&a, &[1, 2, 3, 4, 5, 6, 7]); - /// - /// use std::ops::Range; - /// fn slide<T>(slice: &mut [T], range: Range<usize>, to: usize) { - /// if to < range.start { - /// slice[to..range.end].rotate(range.start-to); - /// } else if to > range.end { - /// slice[range.start..to].rotate(range.end-range.start); - /// } - /// } - /// let mut v: Vec<_> = (0..10).collect(); - /// slide(&mut v, 1..4, 7); - /// assert_eq!(&v, &[0, 4, 5, 6, 1, 2, 3, 7, 8, 9]); - /// slide(&mut v, 6..8, 1); - /// assert_eq!(&v, &[0, 3, 7, 4, 5, 6, 1, 2, 8, 9]); + /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; + /// a.rotate_right(2); + /// assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']); + /// ``` + /// + /// Rotate a subslice: + /// + /// ``` + /// #![feature(slice_rotate)] + /// + /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f']; + /// a[1..5].rotate_right(1); + /// assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']); /// ``` #[unstable(feature = "slice_rotate", issue = "41891")] - pub fn rotate(&mut self, mid: usize) { - core_slice::SliceExt::rotate(self, mid); + pub fn rotate_right(&mut self, k: usize) { + core_slice::SliceExt::rotate_right(self, k); } /// Copies the elements from `src` into `self`. |