Add configuration for min width of line-numbers gutter

[dgkf]

Supercedes #3953

Now that the line-number gutter can be resized (#3469), this exposes options for the currently hard-coded minimum number of characters used in the line-numbers gutter.

Architectural Changes

• GutterConfig & GutterLineNumbersConfig config structs added, allowing for the configuration style suggested in #1188.
• View now accepts a gutters parameter as a GutterConfig object instead of Vec<GutterType>
• Editor::refresh_config() now also refreshes Views to respond to configuration update events

Design feedback needed

• Should editor.gutters provided as an array of strings be deprecated in favor of editor.gutters.layout?

[the-mikedavis]

I wonder if this is necessary after #3469? You would have to be editing a really massive file for the gutter to be noticeably large

[archseer]

Agree, we can offer a configurable minimum but no maximum.

[dgkf]

@the-mikedavis - I can only speak for myself, but I really try to cut down on the unused space in the gutters. In vim I set numberwidth=1 and signcolumn='number', which usually means I usually get away with only 3 columns for both diagnostics and line numbers. Especially when working on a small display, saving a collective 6-10 columns can make the difference with a vertical split or two.

I don't feel as strongly about a maximum, but it seemed like an easy related addition. I would use it if it was available.

[archseer]

I think a min of 2 was deliberate in the previous PR:

The line number gutter will have a minimum width of 2 characters. This is so that configurations using line-number: "relative" aren't adversely affected by this change. In the future, the min/max width could perhaps be configurable and this hard-coded minimum could be removed.

[archseer]

In most cases the line number column is going to be under 5-6 columns (10_000 - 100_000 lines), and any larger than that would be a pain to load fully into memory anyway.

[dgkf]

The line number gutter will have a minimum width of 2 characters. This is so that configurations using line-number: "relative" aren't adversely affected

I suggested this, and in retrospect it wouldn't matter. If a document has <10 lines, then the maximum relative offset is also <10, so you don't need two characters devoted to relative numbering.

Anyways, if this whole PR feels unnecessary to you - that's fine too. Feel free to close the request. Either way I'm grateful for the opportunity to get my fingers into some rust development with a clean codebase and will look for the next task to chip away at.

[dgkf]

Agree, we can offer a configurable minimum but no maximum.

@archseer @the-mikedavis I've altered the implementation so that only minimum linenumber gutter width is configurable. This is ready for review.

[the-mikedavis]

This looks like a good way to configure gutters to me 👍. We will probably end up using this in the future to allow configuration of the characters used for additions/modifications/deletions in the diff gutter element and maybe the separator character (as with the statusline, although I can't imagine anything other than space looking good)

[dgkf]

@the-mikedavis @pascalkuthe - Thank you both for reviewing and for the suggestions on how to better handle the different styles of configuration. I've incorporated your feedback. This PR is now ready for another pass of review.

[hadronized]

What about [editor.gutters.breakpoints]? I’m mentioning this because of what I’m doing in #5371 (I might eventually rebase on your work).

[dgkf]

Right now the sub-sections are styled after the names that can be provided to editor.gutters. There's no real reason it must be like this, but it think there's some discoverability benefit to being consistent here.

Following that style, both breakpoints and diagnostics would be configured in editors.gutters.diagnostics. I think it's best to follow this precedent, but I'd say this is a call for some of the more core contributors like @the-mikedavis

---

Looking into the future a bit further, I think the underlying issue here is that diagnostics and breakpoints are a bit oddly coupled - likely a solution from before gutters were configurable. I think there's a case for decoupling diagnostics and breakpoints and trying to tackle that use case more generically. I think it would be interesting to be able to layer gutters as part of the layout. Perhaps something like:

[editor.gutters]
layout = [ [ "diagnostics", "breakpoints" ], "line-numbers" ]

Which would provide the current behavior. I think that needs more discussion before jumping to something like that, though.

[hadronized]

I’m reimplementing #5371 rebased atop your PR then.

[dgkf]

@the-mikedavis, @archseer - Any chance I can get your eyes on this PR for review? It's beginning to be used by downstream work, so I'm feeling obliged to push it forward.

[hadronized]

Agreed, it would be nice to be able to merge it. Rebasing my PR (#5371) requires rebasing that one so I can’t really be up-to-date with master besides locally rebasing this one. Is there any missing points?

[the-mikedavis]

Looking good overall, just some minor comments

[dgkf]

Thank you for the review today @the-mikedavis - I applied all but one change that I wasn't quite clear on.

[hadronized]

Small nit question: have you rebased on master? If so, even though your PR is not merged yet, I’ll rebase #5371 on yours to follow your changes.

[dgkf]

@phaazon - I rebased onto master so hopefully it's easier on you now if you want to use this as the basis for your changes.