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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /library/alloc/src/collections/vec_deque/ring_slices.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/alloc/src/collections/vec_deque/ring_slices.rs')
-rw-r--r-- | library/alloc/src/collections/vec_deque/ring_slices.rs | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/library/alloc/src/collections/vec_deque/ring_slices.rs b/library/alloc/src/collections/vec_deque/ring_slices.rs new file mode 100644 index 000000000..dd0fa7d60 --- /dev/null +++ b/library/alloc/src/collections/vec_deque/ring_slices.rs @@ -0,0 +1,56 @@ +use core::ptr::{self}; + +/// Returns the two slices that cover the `VecDeque`'s valid range +pub trait RingSlices: Sized { + fn slice(self, from: usize, to: usize) -> Self; + fn split_at(self, i: usize) -> (Self, Self); + + fn ring_slices(buf: Self, head: usize, tail: usize) -> (Self, Self) { + let contiguous = tail <= head; + if contiguous { + let (empty, buf) = buf.split_at(0); + (buf.slice(tail, head), empty) + } else { + let (mid, right) = buf.split_at(tail); + let (left, _) = mid.split_at(head); + (right, left) + } + } +} + +impl<T> RingSlices for &[T] { + fn slice(self, from: usize, to: usize) -> Self { + &self[from..to] + } + fn split_at(self, i: usize) -> (Self, Self) { + (*self).split_at(i) + } +} + +impl<T> RingSlices for &mut [T] { + fn slice(self, from: usize, to: usize) -> Self { + &mut self[from..to] + } + fn split_at(self, i: usize) -> (Self, Self) { + (*self).split_at_mut(i) + } +} + +impl<T> RingSlices for *mut [T] { + fn slice(self, from: usize, to: usize) -> Self { + assert!(from <= to && to < self.len()); + // Not using `get_unchecked_mut` to keep this a safe operation. + let len = to - from; + ptr::slice_from_raw_parts_mut(self.as_mut_ptr().wrapping_add(from), len) + } + + fn split_at(self, mid: usize) -> (Self, Self) { + let len = self.len(); + let ptr = self.as_mut_ptr(); + assert!(mid <= len); + ( + ptr::slice_from_raw_parts_mut(ptr, mid), + ptr::slice_from_raw_parts_mut(ptr.wrapping_add(mid), len - mid), + ) + } +} |