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use core::fmt;
use core::marker::PhantomData;
use core::ops::{Deref, DerefMut};
use core::pin::Pin;
use core::ptr::NonNull;
pub struct AliasableMut<'a, T: ?Sized> {
inner: NonNull<T>,
_lifetime: PhantomData<&'a ()>,
}
impl<'a, T: ?Sized> AliasableMut<'a, T> {
#[inline]
pub fn from_unique(ptr: &'a mut T) -> Self {
Self {
inner: NonNull::from(ptr),
_lifetime: PhantomData,
}
}
#[inline]
pub fn into_unique(ptr: Self) -> &'a mut T {
unsafe { &mut *ptr.inner.as_ptr() }
}
pub fn into_unique_pin(pin: Pin<Self>) -> Pin<&'a mut T> {
unsafe {
let aliasable = Pin::into_inner_unchecked(pin);
Pin::new_unchecked(Self::into_unique(aliasable))
}
}
pub fn from_unique_pin(pin: Pin<&'a mut T>) -> Pin<Self> {
unsafe {
let unique = Pin::into_inner_unchecked(pin);
Pin::new_unchecked(Self::from_unique(unique))
}
}
}
impl<'a, T: ?Sized> From<&'a mut T> for AliasableMut<'a, T> {
fn from(ptr: &'a mut T) -> Self {
Self::from_unique(ptr)
}
}
impl<T: ?Sized> Deref for AliasableMut<'_, T> {
type Target = T;
#[inline]
fn deref(&self) -> &Self::Target {
unsafe { self.inner.as_ref() }
}
}
impl<T: ?Sized> DerefMut for AliasableMut<'_, T> {
#[inline]
fn deref_mut(&mut self) -> &mut Self::Target {
unsafe { self.inner.as_mut() }
}
}
impl<T: ?Sized> AsRef<T> for AliasableMut<'_, T> {
#[inline]
fn as_ref(&self) -> &T {
self
}
}
impl<T: ?Sized> AsMut<T> for AliasableMut<'_, T> {
#[inline]
fn as_mut(&mut self) -> &mut T {
self
}
}
impl<T: ?Sized> fmt::Debug for AliasableMut<'_, T>
where
T: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
unsafe impl<T: ?Sized> Send for AliasableMut<'_, T> where T: Send {}
unsafe impl<T: ?Sized> Sync for AliasableMut<'_, T> where T: Sync {}
#[cfg(feature = "traits")]
unsafe impl<T: ?Sized> crate::StableDeref for AliasableMut<'_, T> {}
#[cfg(feature = "traits")]
unsafe impl<T: ?Sized> crate::AliasableDeref for AliasableMut<'_, T> {}
#[cfg(test)]
mod tests {
use super::AliasableMut;
use alloc::boxed::Box;
use alloc::format;
use core::pin::Pin;
#[test]
fn test_new() {
let mut data = Box::new(10);
let aliasable = AliasableMut::from_unique(&mut data);
assert_eq!(**aliasable, 10);
let unique = AliasableMut::into_unique(aliasable);
assert_eq!(**unique, 10);
}
#[test]
fn test_new_pin() {
let mut data = Box::new(10);
let data = unsafe { Pin::new_unchecked(&mut data) };
let aliasable = AliasableMut::from_unique_pin(data);
assert_eq!(**aliasable, 10);
let unique = AliasableMut::into_unique_pin(aliasable);
assert_eq!(**unique, 10);
}
#[test]
fn test_refs() {
let mut data = Box::new(10);
let mut aliasable = AliasableMut::from_unique(&mut data);
let ptr: *const Box<u8> = &mut *aliasable;
let as_mut_ptr: *const Box<u8> = aliasable.as_mut();
let as_ref_ptr: *const Box<u8> = aliasable.as_ref();
assert_eq!(ptr, as_mut_ptr);
assert_eq!(ptr, as_ref_ptr);
}
#[test]
fn test_debug() {
let mut data = 10;
let aliasable = AliasableMut::from_unique(&mut data);
assert_eq!(format!("{:?}", aliasable), "10");
}
}