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use crate::{AcpiError, AcpiResult};
use core::{
alloc::{Allocator, Layout},
mem,
ptr::NonNull,
};
/// Thin wrapper around a regular slice, taking a reference to an allocator for automatic
/// deallocation when the slice is dropped out of scope.
#[derive(Debug)]
pub struct ManagedSlice<'a, T, A>
where
A: Allocator,
{
slice: &'a mut [T],
allocator: A,
}
impl<'a, T, A> ManagedSlice<'a, T, A>
where
A: Allocator,
{
/// Attempt to allocate a new `ManagedSlice` that holds `len` `T`s.
pub fn new_in(len: usize, allocator: A) -> AcpiResult<Self> {
let layout = Layout::array::<T>(len).map_err(|_| AcpiError::AllocError)?;
match allocator.allocate(layout) {
Ok(mut ptr) => {
let slice = unsafe { core::slice::from_raw_parts_mut(ptr.as_mut().as_mut_ptr().cast(), len) };
Ok(ManagedSlice { slice, allocator })
}
Err(_) => Err(AcpiError::AllocError),
}
}
}
#[cfg(feature = "alloc")]
impl<'a, T> ManagedSlice<'a, T, alloc::alloc::Global> {
pub fn new(len: usize) -> AcpiResult<Self> {
Self::new_in(len, alloc::alloc::Global)
}
}
impl<'a, T, A> Drop for ManagedSlice<'a, T, A>
where
A: Allocator,
{
fn drop(&mut self) {
unsafe {
let slice_ptr = NonNull::new_unchecked(self.slice.as_ptr().cast_mut().cast::<u8>());
let slice_layout =
Layout::from_size_align_unchecked(mem::size_of_val(self.slice), mem::align_of_val(self.slice));
self.allocator.deallocate(slice_ptr, slice_layout);
}
}
}
impl<'a, T, A> core::ops::Deref for ManagedSlice<'a, T, A>
where
A: Allocator,
{
type Target = [T];
fn deref(&self) -> &Self::Target {
self.slice
}
}
impl<'a, T, A> core::ops::DerefMut for ManagedSlice<'a, T, A>
where
A: Allocator,
{
fn deref_mut(&mut self) -> &mut Self::Target {
self.slice
}
}
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