I've been looking for something like this recently, and there are actually quite a few options. Unfortunately, they can only handle files up to a particular size. My use case is to pretty up a huge SQL dump so that I can grab it. Every existing tool tries to read the entire thing into memory, and ends up crashing.
the language server protocol supports range operations, although I don’t know how many editors enable it. plus it’s arguably harder to implement. I will add benchmarks once the server is ready, and we can see how far we can get from there. thanks for the feedback!
it’s on the roadmap! once the parser is stable and an advanced and scalable data model is implemented, features like this will hopefully be quite straightforward to implement.