1// SPDX-License-Identifier: GPL-2.0
 2
 3//! Kernel types.
 4
 5use core::{cell::UnsafeCell, mem::MaybeUninit};
 6
 7/// Stores an opaque value.
 8///
 9/// This is meant to be used with FFI objects that are never interpreted by Rust code.
10#[repr(transparent)]
11pub struct Opaque<T>(MaybeUninit<UnsafeCell<T>>);
12
13impl<T> Opaque<T> {
14    /// Creates a new opaque value.
15    pub const fn new(value: T) -> Self {
16        Self(MaybeUninit::new(UnsafeCell::new(value)))
17    }
18
19    /// Creates an uninitialised value.
20    pub const fn uninit() -> Self {
21        Self(MaybeUninit::uninit())
22    }
23
24    /// Returns a raw pointer to the opaque data.
25    pub fn get(&self) -> *mut T {
26        UnsafeCell::raw_get(self.0.as_ptr())
27    }
28}
29
30/// A sum type that always holds either a value of type `L` or `R`.
31pub enum Either<L, R> {
32    /// Constructs an instance of [`Either`] containing a value of type `L`.
33    Left(L),
34
35    /// Constructs an instance of [`Either`] containing a value of type `R`.
36    Right(R),
37}