Generic Value w/o allocation

[zeenix]

In a project of mine (that's not yet public), I really need a generic Value but it's no-std+no-alloc so I can't use serde_json. I was thrilled to find this crate but was disappointed to see that there's no generic Value type.

I understand that serde_json uses alloc in its Value type (extensively) and that's why it's been documented as a non-goal in the README of this project. However I think it can be implemented without alloc as well, using the stack-based container types (for example, using the heapless crate).

Would this be something maintainers are interested in? If so, I'd be willing to try and make it happen.

[zeenix]

hmm.. actually I had underestimated the job because I didn't think about the recursive nature of the container variants: Array and Object. One can use the pool API of heapless:

use heapless::{Vec, box_pool, pool::boxed::Box};

box_pool!(ValuePool: Value);

#[derive(Debug)]
pub enum Value {
    Int(i32),
    Float(f64),
    List(Vec<Box<ValuePool>, CONTAINER_SIZE>),
}

const CONTAINER_SIZE: usize = 16;

but that comes with a few caveats and limitations, mainly that heapless::pool mod is only available for x86 (not x86_64) and arm_llsc targets. The git main of heapless has experimental support for x86_64 but I don't think that's a typical target used with this crate. :)