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#![allow(unsafe_code)]
use crate::GetDisjointMutError;
/// Like `slice::get_disjoint_mut`, although we're not dealing with ranges (yet).
// TODO(MSRV 1.86): remove this in favor of the standard library's method.
pub(super) fn get_disjoint_mut<T, const N: usize>(
entries: &mut [T],
indices: [usize; N],
) -> Result<[&mut T; N], GetDisjointMutError> {
// SAFETY: Can't allow duplicate indices as we would return mutable refs to the same data.
let len = entries.len();
for i in 0..N {
let idx = indices[i];
if idx >= len {
return Err(GetDisjointMutError::IndexOutOfBounds);
} else if indices[..i].contains(&idx) {
return Err(GetDisjointMutError::OverlappingIndices);
}
}
let entries_ptr = entries.as_mut_ptr();
Ok(indices.map(move |idx| {
// SAFETY: The base pointer is valid as it comes from a slice and the reference is always
// in-bounds & unique as we've already checked the indices above.
unsafe { &mut *(entries_ptr.add(idx)) }
}))
}
/// Like `slice::get_disjoint_mut` but with optional indices,
/// allowing for absent keys from the user's original request.
#[track_caller]
pub(super) fn get_disjoint_opt_mut<T, const N: usize>(
entries: &mut [T],
indices: [Option<usize>; N],
) -> [Option<&mut T>; N] {
// SAFETY: Can't allow duplicate indices as we would return mutable refs to the same data.
let len = entries.len();
for i in 0..N {
if let Some(idx) = indices[i] {
if idx >= len {
unreachable!("`get_index_of` returned an out-of-bounds index");
} else if indices[..i].contains(&Some(idx)) {
panic!("duplicate keys found");
}
}
}
let entries_ptr = entries.as_mut_ptr();
indices.map(move |idx_opt| {
match idx_opt {
Some(idx) => {
// SAFETY: The base pointer is valid as it comes from a slice and the reference is always
// in-bounds & unique as we've already checked the indices above.
Some(unsafe { &mut *entries_ptr.add(idx) })
}
None => None,
}
})
}