Butcher

An easy way to interact with Cowed structs and enums.

This crate proposes some simple solutions to the most common patterns I met while working with Cows in Rust. It currently fixes two patterns: destructuring and iteration related to objects wrapped in Cow.

Destructuring

The Butcher trait can be used when it is necessary to destruture something wrapped in a Cow. Below is a simple example:

use std::borrow::Cow;
use butcher::Butcher;

#[derive(Butcher, Clone)]
struct MyNumberList {
val: u32,
next: Option<Box<MyNumberList>>,
}

fn destructure_list_elem(i: Cow<MyNumberList>) -> (Cow<u32>, Cow<Option<Box<MyNumberList>>>) {
let ButcheredMyNumberList { val, next } = Butcher::butcher(i);

(val, next)
}

The Butcher procedural macro can be derived for structs and for enums.

Iteration

Here is a demonstration of how to iterate over an object wrapped in a Cow:

use std::borrow::Cow;
use butcher::iterator::{CowIter, IntoCowIterator};

fn print_numbers(elems: Cow<[u32]>) {
let mut iter = elems.into_cow_iter();

for element in iter {
// The type of element is Cow<u32>
println!("{:?}", element);
}
}

See the documentation of CowIter for more information.