#hash #rc #reference #identity #reference-identity


A simple NewType that wraps Rc<T> and allows to use the reference identity/pointer value of Rc<T> as keys in hashmap

1 unstable release

Uses old Rust 2015

0.1.0 Jun 23, 2017

#51 in #rc

37 downloads per month

Custom license

74 lines


This is a small helper crate to use Rc<T> as hash keys where equality is supposed to be determined by the underlaying reference identity (i.e. by the value of the pointer). It provides a type HashByRef<T> that can be used as key in the hashmap.

Quick Start

hash_by_ref = "0.1.0"
    use std::collections::HashMap;
    use std::rc::Rc;
    use hash_by_ref::HashByRef;

    let r1 = Rc::new(1);
    let r2 = Rc::new(1);
    let r3 = r1.clone();
    let mut h = HashMap::new();
    assert_eq!(h[&HashByRef::new(r1.clone())], 1);
    assert_eq!(h[&HashByRef::new(r2.clone())], 2);
    assert_eq!(h[&HashByRef::new(r3.clone())], 1);

No runtime deps