Question is how to do these in Rust. An example might be a browser DOM: each node has a parent pointer, a list of child pointers, left and right sibling pointers, maybe a CSS node pointer, etc. Inserting or deleting nodes has to repair the pointers to and from the neighboring nodes as needed.

I know this is doable since obviously Servo (Rust's initial driving application) has to do it. I hope the answer doesn't involve the word "unsafe". But I am quite unclear about how to create such a structure under Rust's rules of pointer ownership, and also how to reliably reclaim storage when nodes and trees/subtrees are deleted. Plus there will be thread safety rules that should be statically enforced if possible.

I've heard that doubly linked lists in Rust are handled by an unsafe library, yet this seems even worse. Thanks.

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[–] arendjr 5 points 2 weeks ago

Another data structure that you can consider is the red green tree: https://willspeak.me/2021/11/24/red-green-syntax-trees-an-overview.html

We use it in Biome too, and it’s great for building trees that are immutable and yet still need frequent updates, as well as traversal in all directions. Its implementation contains quite a bit of unsafe to make it fast, though as a consumer you’re not really exposed to that.