Expand description
Faster, more compact implementation of Cow
.
Changelog - Cargo - Repository
use beef::Cow;
let borrowed: Cow<str> = Cow::borrowed("Hello");
let owned: Cow<str> = Cow::owned(String::from("World"));
assert_eq!(
format!("{} {}!", borrowed, owned),
"Hello World!",
);
There are two versions of Cow
exposed by this crate:
beef::Cow
is 3 words wide: pointer, length, and capacity. It stores the ownership tag in capacity.beef::lean::Cow
is 2 words wide, storing length, capacity, and the ownership tag all in one word.
Both versions are leaner than the std::borrow::Cow
:
use std::mem::size_of;
const WORD: usize = size_of::<usize>();
assert_eq!(size_of::<std::borrow::Cow<str>>(), 4 * WORD);
assert_eq!(size_of::<beef::Cow<str>>(), 3 * WORD);
// Lean variant is two words on 64-bit architecture
#[cfg(target_pointer_width = "64")]
assert_eq!(size_of::<beef::lean::Cow<str>>(), 2 * WORD);
Modules
- This module contains the actual, albeit generic, implementaiton of the
Cow
, and the traits that are available to it. - Namespace containing the 2-word
Cow
implementation.
Type Aliases
- Compact three word
Cow
that puts the ownership tag in capacity. This is a type alias, for documentation seebeef::generic::Cow
.