multi-array-list 0.2.1

#![allow(incomplete_features)]
#![feature(generic_const_exprs)]

use std::alloc;
use std::env;

use cap::Cap;
use multi_array_list::MultiArrayList;

#[global_allocator]
static ALLOCATOR: Cap<alloc::System> = Cap::new(alloc::System, usize::max_value());

#[derive(Clone, PartialEq, Eq, Debug)]
struct Pizza {
    radius: i32,
    toppings: Vec<Topping>,
}

#[derive(Clone, PartialEq, Eq, Debug)]
#[repr(u8)]
#[allow(dead_code)]
enum Topping {
    Tomato,
    Mozzarella,
    Anchovies,
}

fn main() {
    let n: usize = env::args()
        .skip(1)
        .next()
        .unwrap_or_else(String::new)
        .parse()
        .unwrap_or(500);

    let alloc_start = ALLOCATOR.allocated();

    let _vec: Vec<_> = (0..n)
        .map(|i| Pizza {
            radius: i as i32,
            toppings: vec![],
        })
        .collect();

    let alloc_after_vec = ALLOCATOR.allocated();
    let vec_diff = alloc_after_vec - alloc_start;

    let mut list = MultiArrayList::<Pizza>::new();
    for i in 0..n {
        list.push(Pizza {
            radius: i as i32,
            toppings: vec![],
        });
    }

    let alloc_after_list = ALLOCATOR.allocated();
    let diff = alloc_after_list - alloc_after_vec;
    let ratio = -(100.0 - (diff as f64) / (vec_diff as f64) * 100.0);

    println!("Allocating {n} pizzas.");
    println!("Vec allocated:  {vec_diff} bytes");
    println!("List allocated: {diff} bytes ({ratio:.2}%)");
}