//! Implement a Fallible Rc

use super::FallibleBox;

use crate::TryReserveError;

use alloc::boxed::Box;

use alloc::rc::Rc;

/// trait to implement Fallible Rc

#[cfg_attr(

    any(not(feature = "unstable"), feature = "rust_1_57"),

    deprecated(

        since = "0.4.9",

        note = "⚠️️️this function is not completely fallible, it can panic!, see [issue](https://github.com/vcombey/fallible_collections/issues/13). help wanted"

    )

)]

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;

}

#[allow(deprecated)]

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());

    }

}