1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

//! Static container type with interior mutability

use core::cell::UnsafeCell;
use core::fmt::{self, Debug};
use core::marker::Sync;
use core::ops::Deref;

/// Container usable as a static that allows getting a mutable reference
/// to it's interior value.
pub struct UnsafeContainer<T: ?Sized>(UnsafeCell<T>);

unsafe impl<T: ?Sized + Send> Sync for UnsafeContainer<T> {}
unsafe impl<T: ?Sized + Send> Send for UnsafeContainer<T> {}

impl<T> UnsafeContainer<T> {
	/// Create a new container.
	pub const fn new(t: T) -> UnsafeContainer<T> {
		UnsafeContainer(UnsafeCell::new(t))
	}

	/// Consume this container and return the interior value.
	pub fn into_inner(self) -> T {
		self.0.into_inner()
	}

	/// Replace the interior value, returning the old one
	pub fn replace(&self, t: T) -> T {
		return core::mem::replace(self.get(), t);
	}

	/// Get a mutable reference to the interior value.
	pub fn get<'a>(&self) -> &'a mut T {
		unsafe { &mut *self.0.get() }
	}
}

impl<T: ?Sized> Deref for UnsafeContainer<T> {
	type Target = T;
	fn deref<'a>(&'a self) -> &'a T {
		unsafe { &*self.0.get() }
	}
}

impl<T> Default for UnsafeContainer<T>
where
	T: Default,
{
	fn default() -> UnsafeContainer<T> {
		Self::new(Default::default())
	}
}

impl<T> Debug for UnsafeContainer<T>
where
	T: Debug,
{
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		f.debug_tuple("UnsafeContainer").field(self.get()).finish()
	}
}