Indices

Zero allocation macros for retrieving multiple mutable indices from a mutable slice safely. e.g.

let (two, four) = indices!(slice, 2, 4);

Another e.g.

fn main() {
    struct Person {
        first: String,
        last: String,
    }
    let mut data = [
        Person { first: "John".to_string(), last: "Doe".to_string() },
        Person { first: "Jane".to_string(), last: "Smith".to_string() },
        Person { first: "Alice".to_string(), last: "Johnson".to_string() },
        Person { first: "Bob".to_string(), last: "Brown".to_string() },
        Person { first: "Charlie".to_string(), last: "White".to_string() },
    ];
    fn modify(data_slice: &mut [Person], index: usize){
        let (four, func_provided, three) = indices!(data_slice, 4, index, 3);
        four.last = "Black".to_string();
        func_provided.first = "Jack".to_string();
        three.last = "Jones".to_string();
    }
    let slice = data.as_mut_slice();
    modify(slice, 1);
    assert_eq!(data[4].last, "Black");
    assert_eq!(data[1].first, "Jack");
    assert_eq!(data[3].last, "Jones");
}

The following macros are provided:

indices!
try_indices!
indices_ordered!
try_indices_ordered!