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//! Implement a Fallible Rc
use super::FallibleBox;
use crate::TryReserveError;
use alloc::boxed::Box;
use alloc::rc::Rc;
/// trait to implement Fallible Rc
pub trait FallibleRc<T> {
/// try creating a new Rc, returning a Result<Box<T>,
/// TryReserveError> if allocation failed
fn try_new(t: T) -> Result<Self, TryReserveError>
where
Self: Sized;
}
impl<T> FallibleRc<T> for Rc<T> {
fn try_new(t: T) -> Result<Self, TryReserveError> {
let b = <Box<T> as FallibleBox<T>>::try_new(t)?;
Ok(Rc::from(b))
}
}
#[cfg(test)]
mod test {
#[test]
fn fallible_rc() {
use std::rc::Rc;
let mut x = Rc::new(3);
*Rc::get_mut(&mut x).unwrap() = 4;
assert_eq!(*x, 4);
let _y = Rc::clone(&x);
assert!(Rc::get_mut(&mut x).is_none());
}
}