octree.rs

use std::sync::Arc;

enum Octree<B, A>
  { Branch
      { preview  : B
      , subtrees : [Arc<Octree<B, A>>; 8]
      }
  , Atom
      { leaf    : A
      , preview : B
      }
  }

type Path = Vec<usize>;

trait IsOctree<'bounded> {
  fn lookup(path : Path, it : &'bounded Arc<Self>) -> &'bounded Arc<Self>;
  // fn update(path : Path, value : Self, it : &Self) -> Self;
}

impl <'bounded, A : 'static, B : 'static> IsOctree<'bounded> for Octree<B, A> {
  fn lookup(path : Path, it : &'bounded Arc<Octree <B, A>>) -> &'bounded Arc<Octree<B, A>> {
    let mut ptr = it;
    for i in path {
      match &**ptr {
        | Octree::Atom {leaf, preview} => return &ptr,
        | Octree::Branch {preview, subtrees} =>
            ptr = &subtrees[i]
      }
    }
    return &it
  }

  // fn update(path : Path, val : Octree <B, A>, it : &Octree <B, A>) -> Octree<B, A> {
  //   return *it
  // }
}

fn main() {
    println!("Hello, world!");
}