Rust code shared from the playground

playground.rs

#![allow(dead_code)]

mod sealer_unsealer {
    use std::rc::Rc;
    use std::ptr;

    pub struct Sealed<T> {
        value: T,
        brand: Rc<Brand>
    }

    pub struct SealerUnsealerPair {
        brand: Rc<Brand>
    }

    struct Brand;

    impl SealerUnsealerPair {
        pub fn new() -> SealerUnsealerPair {
            // Generate a fresh key.
            SealerUnsealerPair { brand: Rc::new(Brand) }
        }

        pub fn seal<T>(&self, value: T) -> Sealed<T> {
            Sealed { value, brand: self.brand.clone() }
        }


        pub fn unseal<T>(&self, sealed: Sealed<T>) -> Option<T> {
            match ptr::eq(&*self.brand, &*sealed.brand) {
                true => Some(sealed.value),
                false => None,
            }
        }
    }
}

#[test]
fn test() {
    use sealer_unsealer::SealerUnsealerPair;

    let sealer1 = SealerUnsealerPair::new();
    let sealer2 = SealerUnsealerPair::new();
    let sealed1 = sealer1.seal("foo");
    let sealed2 = sealer2.seal("bar");
    let sealed1_2 = sealer1.seal("abc");
    let sealed2_2 = sealer2.seal("xyz");
    assert!(sealer1.unseal(sealed1).is_some());
    assert!(sealer1.unseal(sealed2).is_none());
    assert!(sealer2.unseal(sealed2_2).is_some());
    assert!(sealer2.unseal(sealed1_2).is_none());
}