Skip to content

Implement as_chunks with split_at_unchecked #124793

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
May 9, 2024
Merged

Implement as_chunks with split_at_unchecked #124793

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 8 additions & 4 deletions library/core/src/slice/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1337,8 +1337,10 @@ impl<T> [T] {
#[must_use]
pub const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T]) {
assert!(N != 0, "chunk size must be non-zero");
let len = self.len() / N;
let (multiple_of_n, remainder) = self.split_at(len * N);
let len_rounded_down = self.len() / N * N;
// SAFETY: The rounded-down value is always the same or smaller than the
// original length, and thus must be in-bounds of the slice.
let (multiple_of_n, remainder) = unsafe { self.split_at_unchecked(len_rounded_down) };
// SAFETY: We already panicked for zero, and ensured by construction
// that the length of the subslice is a multiple of N.
let array_slice = unsafe { multiple_of_n.as_chunks_unchecked() };
Expand Down Expand Up @@ -1487,8 +1489,10 @@ impl<T> [T] {
#[must_use]
pub const fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T]) {
assert!(N != 0, "chunk size must be non-zero");
let len = self.len() / N;
let (multiple_of_n, remainder) = self.split_at_mut(len * N);
let len_rounded_down = self.len() / N * N;
// SAFETY: The rounded-down value is always the same or smaller than the
// original length, and thus must be in-bounds of the slice.
let (multiple_of_n, remainder) = unsafe { self.split_at_mut_unchecked(len_rounded_down) };
// SAFETY: We already panicked for zero, and ensured by construction
// that the length of the subslice is a multiple of N.
let array_slice = unsafe { multiple_of_n.as_chunks_unchecked_mut() };
Expand Down