orx-fixed-vec

FixedVec implements PinnedVec; therefore,

• it preserves the memory locations of already pushed elements.

This feature eliminates a specific set of errors leading to undefined behavior, and hence, allows to work with a more flexible borrow checker.

Furthermore, it can be used as the underlying pinned vector of an ImpVec, which adds the additional feature to push to the vector with an immutable reference.

Unlike, another pinned vector implementation SplitVec, FixedVec allows operations with same complexity and speed of std::vec::Vec.

Its drawback, on the other hand, is that:

• it has a hard limit on its capacity,
• it will panic if the caller attempts to extend the vector beyond this limit.

use orx_fixed_vec::prelude::*;

let fixed_capacity = 42;
let mut vec = FixedVec::new(fixed_capacity);
assert_eq!(fixed_capacity, vec.capacity());

let mut initial_addresses = vec![];
for i in 0..fixed_capacity {
    vec.push(i);
    initial_addresses.push(vec.get(i).unwrap() as *const usize);
}

assert_eq!(fixed_capacity, vec.len());
assert_eq!(0, vec.room());
assert!(vec.is_full());

// addresses of already pushed elements stay intact
let final_addresses: Vec<_> = (0..fixed_capacity)
    .map(|i| vec.get(i).unwrap() as *const usize)
    .collect();
assert_eq!(initial_addresses, final_addresses);

// the next push when `vec.is_full()` panics!
// vec.push(42);