Crate bos[−][src]

Expand description

This crate provides flexible Borrowed, Owned or Shared (B.O.S.) smart pointers. They are like std’s Cow but with additonal Arc and Rc variants. Unlike std’s Cow, they can also be used with types that don’t implement Clone or ToOwned.

The bos smart pointers allow you to:

share data efficiently
decide ownership at runtime
avoid cloning the data until it becomes necessary

“A” stands for “atomic”

For example Abos implements Send and Sync but does not have a Rc variant.

Bos does not implement Send or Sync but does have a Rc variant.

`AbosStr` and `BosStr` types

Abos and Bos are often used with str or similar types. Feel free to have a look at our handy type aliases below.

`serde` feature

For serde support, you need to enable our serde feature:

[dependencies]
bos = { version = "?", features = ["serde"] }

Replace version = "?" with the version you want.

Examples

use std::sync::Arc;
use bos::AbosStr;

// No need to allocate memory for a &'static str
let title = AbosStr::Borrowed("Dune");

// The author's name shouldn't be too long.
// So we can just store it in a normal String.
let author = AbosStr::Owned(read_file("dune/author.txt"));

// A whole book is really long.
// And we want to share this string with multiple threads.
// So it would be efficient to store in an Arc,
// since cloning the Arc does not clone the String data inside of it.
let book_text = AbosStr::Arc(Arc::new(read_file("dune/book.txt")));

// We can store a &str, String and Arc<String> inside the same Vec
// because we are using the AStr enum.
let book_infos: Vec<AbosStr> = vec![title, author, book_text];

fn read_file(path: &str) -> String {
    // ...
}

This example shows how to use Abos in a struct:

use bos::{AbosStr, AbosBrw};
use std::sync::Arc;

#[derive(Debug, Eq, PartialEq)]
struct Header<'a> {
    // AbosStr<'a> is a type alias for AbosBrw<'a, str>
    // and results in a type of Abos<'a, str, String>
    name: AbosStr<'a>,
    value: AbosStr<'a>,
}

// The struct with 'static is still very useful
// because it is not limited to &'static str.
// String and Arc<String> can be used, too.
fn add_global_header(header: Header<'static>) {
    // ...
}

// Let's pretend this header came over the network
// and was parsed into our Header struct.
let header = Header {
    name: AbosStr::Owned(String::from("content-type")),
    value: AbosStr::Arc(Arc::new(String::from("text/html; charset=UTF-8"))),
};

add_global_header(header);