HeapArray

This crate aims to give people better control of how they want to allocate memory, by providing a customizable way to allocate blocks of memory, that optionally contains metadata about the block itself.

Features

• Arrays are allocated on the heap, with optional extra space allocated for metadata
• An array implementation that uses an atomic pointer (heaparray::thin_array_ptr::ThinPtrArray)
• 1-word and 2-word references to arrays
• Atomically reference-counted memory blocks of arbitrary size without using a Vec
• Swap owned objects in and out with array.insert()
• Arbitrarily sized objects using label and an array of bytes (u8)

Examples

Creating an array:

use heaparray::*;
let len = 10;
let array = HeapArray::new(len, |idx| idx + 3);
assert!(array[1] == 4);

Indexing works as you would expect:

array[3] = 2;
assert!(array[3] == 2);

Notably, you can take ownership of objects back from the container:

let mut array = HeapArray::new(10, |_| Vec::<u8>::new());
let replacement_object = Vec::new();
let owned_object = array.insert(0, replacement_object);

but you need to give the array a replacement object to fill its slot with.

Additionally, you can customize what information should be stored alongside the elements in the array using the HeapArray::new_labelled function:

struct MyLabel {
    pub even: usize,
    pub odd: usize,
}

let mut array = HeapArray::new_labelled(
    MyLabel { even: 0, odd: 0 },
    100,
    |label, index| {
        if index % 2 == 0 {
            label.even += 1;
            index
        } else {
            label.odd += 1;
            index
        }
    });

Use of unsafe Keyword

This library relies heavily on the use of the unsafe keyword to do both reference counting and atomic operations; there are 14 instances total, not including tests.

Future Plans

Iteration, allocator customization, reference counting (RcArray), and atomic reference counting (ArcArray). Constant-sized array of arbitrary size, i.e. CArray, with sizes managed by the type system (waiting on const generics for this one). See TODO.md in the repository for a full list of planned features.