Concatenate array slices

Question

I have two (very large) arrays foo and bar of the same type. To be able to write some nice code, I would like to obtain a read-only slice, result

Answer 1

For n arrays, you can implement it using a Vec like below:

use std::ops::Index;

struct VecSlice<'a, T: 'a>(Vec<&'a [T]>);

impl<'a, T> Index for VecSlice<'a, T> {
    type Output = T;
    fn index(&self, mut index: usize) -> &T {
        for slice in self.0.iter() {
            if index < slice.len() {
                return &slice[index];
            } else {
                index -= slice.len();
            }
        }
        panic!("out of bound");
    }
}

And then access it like an array, just don't go out of bound.

fn main() {
    let a1 = [0, 1, 2];
    let a2 = [7, 8, 9];
    let a = VecSlice(vec!(&a1, &a2));
    println!("{}", a[4]);
}

This prints out

8