use std::cell::UnsafeCell;
use std::ops::Deref;
use std::rc::{Rc, Weak};
pub(crate) struct Cell<T> {
inner: Rc<UnsafeCell<T>>,
}
pub(crate) struct WeakCell<T> {
inner: Weak<UnsafeCell<T>>,
}
impl<T> Clone for Cell<T> {
fn clone(&self) -> Self {
Self {
inner: self.inner.clone(),
}
}
}
impl<T> Deref for Cell<T> {
type Target = T;
fn deref(&self) -> &Self::Target {
self.get_ref()
}
}
impl<T: std::fmt::Debug> std::fmt::Debug for Cell<T> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
self.inner.fmt(f)
}
}
impl<T> Cell<T> {
pub fn new(inner: T) -> Self {
Self {
inner: Rc::new(UnsafeCell::new(inner)),
}
}
pub fn downgrade(&self) -> WeakCell<T> {
WeakCell {
inner: Rc::downgrade(&self.inner),
}
}
pub fn get_ref(&self) -> &T {
unsafe { &*self.inner.as_ref().get() }
}
pub fn get_mut(&self) -> &mut T {
unsafe { &mut *self.inner.as_ref().get() }
}
}
impl<T: std::fmt::Debug> std::fmt::Debug for WeakCell<T> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
self.inner.fmt(f)
}
}
impl<T> WeakCell<T> {
pub fn upgrade(&self) -> Option<Cell<T>> {
if let Some(inner) = self.inner.upgrade() {
Some(Cell { inner })
} else {
None
}
}
}