#box #dst #dyn #collection #avoid

no-std tinybox

Like Box, but with an optimization that avoids allocations for small data-structures

4 releases (2 breaking)

0.3.1 Jan 4, 2023
0.3.0 Jan 3, 2023
0.2.0 Jan 7, 2022
0.1.0 Jan 7, 2022

#721 in Data structures


Used in pulz-schedule

MIT/Apache

24KB
502 lines

tinybox

Crates.io docs.rs license: MIT/Apache-2.0 Rust CI

TinyBox is like Box, but with an optimization that avoids allocations for small data-structures. This works by storing the value-bits inside the box itself, when the data-structure fits inside a pointer. This is especially usefull for dynamically sized types like traits.

Example

This example stores a value inside the TinyBox without requireing an allocation.

use tinybox::TinyBox;
let boxed = TinyBox::new(1234usize);
assert_eq!(1234, *boxed)

This looks not very usefull, because the value can be stored inside a usize variable without TinyBox. Here is an more useful example that uses dyn-traits. The tinybox! macro is used to coerce the value to a dyn-trait in stable-rust.

use std::any::{Any,TypeId};
use tinybox::{tinybox, TinyBox};
let boxed: TinyBox<dyn Any> = tinybox!(dyn Any => 1234usize);
assert_eq!(TypeId::of::<usize>(), (*boxed).type_id());
assert_eq!(1234, *boxed.downcast::<usize>().unwrap());

no_std

This crate should also work without std. No additional configuration required.

License

This repository is licensed under either of

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

No runtime deps