owning-ref-rs
A library for creating references that carry their owner with them.
This can sometimes be useful because Rust borrowing rules normally prevent moving a type that has been borrowed from. For example, this kind of code gets rejected:
fn return_owned_and_referenced<'a>() -> (Vec<u8>, &'a [u8]) {
let v = vec![1, 2, 3, 4];
let s = &v[1..3];
(v, s)
}This library enables this safe usage by keeping the owner and the reference bundled together in a wrapper type that ensure that lifetime constraint:
fn return_owned_and_referenced() -> OwningRef<Vec<u8>, [u8]> {
let v = vec![1, 2, 3, 4];
let or = OwningRef::new(v);
let or = or.map(|v| &v[1..3]);
or
}Getting Started
To get started, add the following to Cargo.toml.
owning_ref = "0.4.1"...and see the docs for how to use it.
Example
extern crate owning_ref;
use owning_ref::BoxRef;
fn main() {
// Create an array owned by a Box.
let arr = Box::new([1, 2, 3, 4]) as Box<[i32]>;
// Transfer into a BoxRef.
let arr: BoxRef<[i32]> = BoxRef::new(arr);
assert_eq!(&*arr, &[1, 2, 3, 4]);
// We can slice the array without losing ownership or changing type.
let arr: BoxRef<[i32]> = arr.map(|arr| &arr[1..3]);
assert_eq!(&*arr, &[2, 3]);
// Also works for Arc, Rc, String and Vec!
}