Feature request: clone method

[danvk]

I've implemented clone this way:

const newTree = rbush();
newTree.fromJSON(JSON.parse(JSON.stringify(tree.toJSON())));

but I imagine there might be a faster way for rbush itself to do this.

(My use case is that I'd like to create a new version of the tree with a few additional locations added.)

[mourner]

Thanks for the request! Would you expect RBush to clone the tree structure but don't clone the items from the original input array (and keep references instead)?

[danvk]

Yes, that's exactly what I'd want!

[mourner]

Great! If you want to tackle this, I'm happy to review a PR.

[Pyrolistical]

To keep the references, I believe current way to do it is:

function clone(tree) {
  const cloned = Rbush()
  cloned.load(tree.all())
  return cloned
}

[mourner]

@Pyrolistical this would be sub-optimal due to the need to perform loading again — in theory, this step could be avoided with selective tree cloning. But this probably won't be a bottleneck anyway.

[Pyrolistical]

Understood. I was just showing how you would do it. Its not great.

Maybe if you refactored to use a persistent data structure then you can have zero cost clone.