Implement LSP window/showDocument request

[MDeiml]

Implements the LSP request for window/showDocument.

This does not yet implement requests with the external parameter set to true, but it would probably best to do this in the same PR (as LSP servers would probably assume that to work). I believe there is no similar functionality in helix yet, and I wanted to check if my suggested approach would be welcome.

I suggest adding a External variant to the Action enum which is passed to Editor::open. The actual implementation could either be done using the open crate or by reimplementing the functionality of this crate.

[MDeiml]

Thanks for the quick feedback :)

[poliorcetics]

You can avoid adding a new method by simply storing the offset_encoding earlier and keeping it for the duration of the method, since that type is Copy it won't carry the borrow of self.editor

[MDeiml]

You can avoid adding a new method by simply storing the offset_encoding earlier and keeping it for the duration of the method, since that type is Copy it won't carry the borrow of self.editor

Hm, that would work, but I would need to call get_by_id again after the match block. I feel like it's a bit neater with the Arc. Also future contributions might also need the Arc in this method or other places so it probably makes sense for Registry to have this method.

[poliorcetics]

Ah I didn't check if the language server itself was used later

[MDeiml]

Should be ready to merge now. It would also make sense to wait on Byron/open-rs#64.

[matoous]

There’s open PR for opening files externally: #5820

[MDeiml]

Oh, the open PR was merged in the meantime. So I guess it's worth waiting for #5820 and rebasing the changes on that to support opening externally.

[matoous]

@MDeiml I am sorry, I completely forgot about existence of this PR 🙈 here's second implementation of this based on the PR for handling opening documents in external programs: #8865

[MDeiml]

@matoous haha I already saw it, no worries. Let's just use yours then.

[pascalkuthe]

Closing in favor of #8865 as discussed above. Thanks for working on this @MDeiml