If switching away from an empty scratch buffer, remove it

[Omnikar]

https://matrix.to/#/!zMuVRxoqjyxyjSEBXc:matrix.org/$UF70A_vWmDH5EawsTQLnyLVp0qIqokNwVI4aRFXdEd4?via=matrix.org&via=tchncs.de&via=nixos.dev

When I use Helix, I tend to start it with no arguments and then space f and open a file. As a result, the scratch buffer which opened when I first started the editor remains in the buffer list, and this has been annoying me. I'd prefer if, when switching buffers, if a scratch buffer has no path and is not modified (meaning that it is empty), that it be automatically removed (given that no open view currently displays the buffer).

I had to do some stuff to get around borrow errors.

[archseer]

How about first changing the view.doc and view.offset (L263/264)? This way you don't need to check for view.id != view!(self).id) here and we can extract this traversal into a method

[Omnikar]

That would require using view_mut! twice: once to set view.doc and view.offset, and once after borrowing self.tree for the check, which I suppose isn't necessarily wrong, but I just don't like it. We could alternatively do this:

self.tree.traverse().filter(|(_, view)| view.doc == doc.id).count() > 1

[archseer]

Ah I see. We want to at least get rid of the view! calls inside any, since that costs as much as a view_mut but would be called per iteration here. On L235 we already borrow view so you should be able to reuse that:

• change L235 to let (view, doc) = current_ref!(self)
• remove L241 (let doc = doc!(self);)
• change any to .any(|(_, v)| v.doc == doc.id && v.id != view.id);

[archseer]

Ah I see. We want to at least get rid of the view! calls inside any, since that costs as much as a view_mut but would be called per iteration here. On L235 we already borrow view so you should be able to reuse that:

• change L235 to let (view, doc) = current_ref!(self)
• remove L241 (let doc = doc!(self);)
• change any to .any(|(_, v)| v.doc == doc.id && v.id != view.id);

[archseer]

After the change to current_ref, this can now be simplified to

Suggested change

	self.documents[view.doc].selection(view.id).clone(),
	doc.selection(view.id).clone(),

[archseer]

It would be good to also move this jump definition into if !remove_empty_scratch. That way we're only constructing and cloning the selection if we actually need the jump. To do that we would need to use view_mut! twice, but that's cheaper than a clone