compact_arena

This is a crate with arenas that work with indices. Currently there are three types: SmallArena uses 32-bit indices and can hold up to 2³² objects. TinyArena uses 16-bit indices and can hold up to 65536 objects, regardless of object size. NanoArena uses 8-bit indices and contain up to 256 objects.

This can conserve memory in scenarios where we have a large-ish number of relations between objects, e.g. in graph algorithms. NanoArena is likely most useful in embedded scenarios.

Usage:

Add the following dependency to your Cargo.toml

compact_arena = "0.3"

By default, the TinyArena uses no unsafe code to maintain storage, but requires the stored types to be Default + Copy. To change this, you can use the uninit feature to enable usage on all types with a bit more unsafe code:

compact_arena = { version = "0.3", features = ["alloc", "uninit"] }

In your code, use it as follows:

use compact_arena::mk_arena;

mk_arena!(arena);
let hello = arena.add("Hello");
let world = arena.add("World");
println!("{}, {}!", arena[hello], arena[world]);

For further information, please read the documentation.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

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.