heaparray

This crate aims to give people better control of how they allocate memory, by providing a customizable way to allocate blocks of memory, that optionally contains metadata about the block itself. This makes it much easier to implement Dynamically-Sized Types (DSTs), and also reduces the number of pointer indirections necessary to share data between threads.

Features

• Safe API to dynamically-sized types
• Generic implementations of common tasks so you can customize the implementation of a type without having to write additional boilerplate
• Atomically reference-counted memory blocks of arbitrary size without using a Vec; this means you can access reference-counted memory with only a single pointer indirection.

Examples

Creating an array:

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

Indexing works as you would expect:

rust use heaparray::*; let mut array = HeapArray::new(10, |_| 0); array[3] = 2; assert!(array[3] == 2);

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

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

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

Dynamically Sized Types

The Rust documentation on exotically sized types, at the end of the section on dynamically-sized types states that:

Currently the only properly supported way to create a custom DST is by making your type generic and performing an unsizing coercion... (Yes, custom DSTs are a largely half-baked feature for now.)

This crate aims to provide some of that functionality; the code that the docs give is the following:

```rust struct MySuperSliceable { info: u32, data: T }

fn main() { let sized: MySuperSliceable<[u8; 8]> = MySuperSliceable { info: 17, data: [0; 8], };

let dynamic: &MySuperSliceable<[u8]> = &sized;

// prints: "17 [0, 0, 0, 0, 0, 0, 0, 0]"
println!("{} {:?}", dynamic.info, &dynamic.data);

} ```

using this crate, the MySuperSliceable<[u8]> type would be implemented like this:

```rust use heaparray::*;

type MySuperSliceable = HeapArray;

fn main() { let info = 17; let len = 8; let dynamic = MySuperSliceable::withlabel(info, len, |,_| 0); println!("{:?}", dynamic); } ```

License: MIT