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Implement as_chunks with split_at_unchecked

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Scott McMurray
2024-05-06 01:04:27 -07:00
parent d287f3e4ee
commit 49af347653
1 changed files with 8 additions and 4 deletions
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library/core/src/slice/mod.rs
+8 -4
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@@ -1337,8 +1337,10 @@ pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, 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() };
@@ -1487,8 +1489,10 @@ pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N> {
#[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() };