OxStr

A compact Rust string type that can hold either borrowed or reference-counted owned data.

OxStr<'a> is conceptually a fusion of Arc<str> and Cow<'a, str>: it can store either a borrowed string slice (&'a str) without allocating or an immutable-length, reference-counted string similar to Arc<str>. Cloning owned values is cheap.

It is designed for use cases where a string is created once from a known input and then reused, cloned, and shared extensively. The OxString type alias is available when a fully owned or 'static value is required.

Rather than using an enum, OxStr has a compact two-word layout containing a pointer and a usize length. The most significant bit of the length identifies whether the value is borrowed or owned. For a borrowed value, the pointer targets the string bytes directly. For an owned value, the pointer targets an allocation containing an atomic reference count followed by the string bytes.

Cloning an owned value increments its atomic reference count; cloning a borrowed value remains borrowed and does not allocate.

use oxstr::OxStr;

let borrowed = OxStr::new("hello");
let owned = OxStr::new_owned("hello");

assert_eq!(borrowed.as_str(), "hello");
assert_eq!(owned.as_str(), "hello");

The concat method allocates one owned value and copies the supplied string slices directly into it:

use oxstr::OxStr;

assert_eq!(OxStr::concat(["foo", " ", "bar"]), "foo bar");

Features:

• serde: to enable serde integration.
• std: to add some extra features relying on the std library (enabled by default, disable if you want no-std compatibility).

License

This project is 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 oxstr by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.