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pub mod interface {
pub trait Mutex {
type Data;
fn lock<'a, R>(&'a self, f: impl FnOnce(&'a mut Self::Data) -> R) -> R;
}
}
use core::cell::UnsafeCell;
pub struct NullLock<T> where T: ?Sized {
data: UnsafeCell<T>,
}
unsafe impl<T> Send for NullLock<T> where T: ?Sized + Send {}
unsafe impl<T> Sync for NullLock<T> where T: ?Sized + Send {}
impl<T> NullLock<T> {
pub const fn new(data: T) -> Self {
Self {
data: UnsafeCell::new(data),
}
}
}
impl<T> interface::Mutex for NullLock<T> {
type Data = T;
fn lock<'a, R>(&'a self, f: impl FnOnce(&'a mut T) -> R) -> R {
let data = unsafe { &mut *self.data.get() };
f(data)
}
}
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