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use tokio::sync::{Mutex, OwnedMutexGuard};
pub struct MappedOwnedMutexGuard<U, T> {
mutex: OwnedMutexGuard<U>,
mapper: Box<dyn (for<'a> Fn(&'a U) -> &'a T) + Send + 'static>,
}
impl<U, T> MappedOwnedMutexGuard<U, T> {
pub fn new<FMap: (for<'a> Fn(&'a U) -> &'a T) + Send + 'static>(
item: OwnedMutexGuard<U>,
map: FMap,
) -> Self {
Self {
mutex: item,
mapper: Box::new(map),
}
}
fn map(&self) -> &T {
(self.mapper)(&*self.mutex)
}
fn map_mut(&mut self) -> &mut T {
let immutable_ref = self.map();
#[allow(mutable_transmutes)]
let mutable_unsafe_ref = unsafe { std::mem::transmute::<&T, &mut T>(immutable_ref) };
mutable_unsafe_ref
}
pub fn extract(self) -> OwnedMutexGuard<U> {
self.mutex
}
}
impl<U, T> AsRef<T> for MappedOwnedMutexGuard<U, T> {
fn as_ref(&self) -> &T {
self.map()
}
}
impl<U, T> AsMut<T> for MappedOwnedMutexGuard<U, T> {
fn as_mut(&mut self) -> &mut T {
self.map_mut()
}
}