feat(tabs): use separators matching current style

[matthis-k]

This is the PR for #569.
This works perfectly for slant and slope, but I am not sure what the behavior for thick and thin is supposed to be.
If you want the behavior to be unchanged I (or you) can change it this to this, which should only change the slant and slope and custom styles:

  local single_char = require("bufferline.config").options.separator_style == "thick"
    or require("bufferline.config").options.separator_style == "thin"
  return {
    single_char and {} or { highlight = separator_hl, text = chars[2] },
    {
      highlight = hl,
      text = name,
      attr = { prefix = tab_click_component(tabpage.tabnr) },
    },
    { highlight = separator_hl, text = chars[single_char and 2 or 1] },
  }

[akinsho]

Hi @matthis-k thanks for the PR, whilst it would be good to have this fixed I definitely would rather not have any regressions with it since this will definitely lead to 1 issue being closed and 3 opened to replace it.

Currently I see

When using your PR i.e. there are strange gaps in between characters which has never historically been the case. I've also never been able to reproduce the parent issue here and am curious what terminal emulator causes this

[matthis-k]

I think I fixed my code, I think the problem was that in your code slant only used one char instead of one on each side.

Here are the results:

• thin
  
• thick
  
• slant
  
• slope
  

The only thing that might be left is modifying the x button to match the style, by adding the character that is on the left in front of it, to match the tabs

[akinsho]

@matthis-k thanks for tweaking it, seems like it looks better now. I've made some code style comments since I think the require is unnecessary and the conditional can be terser still.

[akinsho]

This import should match those above rather than be inline like this i.e.

---@module "bufferline.config"
local config = lazy.require("bufferline.config")

Although it appears the style is already being passed into this function as an argument so I don't thing you need to even be requiring the config at all.

[akinsho]

This check could also be done a little more tersely with something like

local style = config.options.separator_style
local swapped_chars = ({thick = {1, 2}, thin = {1, 2}})[style] or {2, 1}
return {
 { highlight = separator_hl, text = swapped_chars[1] },
 -- ...
 { highlight = separator_hl, text = swapped_chars[2] },

[akinsho]

It's also worth clarifying that it isn't a bug that the sloped style and the minimal tabs don't look the same, they were never intended to. This is a good change but just for clarity the minimal tabs were always initially intended to use the thin style regardless of if a user set sloped or anything like that

[matthis-k]

It's also worth clarifying that it isn't a bug that the sloped style and the minimal tabs don't look the same, they were never intended to. This is a good change but just for clarity the minimal tabs were always initially intended to use the thin style regardless of if a user set sloped or anything like that

Oh I see. I thought it was spposed to work, as you would still use the chars from the style here: local chars = constants.sep_chars[style] or constants.sep_chars.thin (so it should be terminal agnostic), but I guess it's in the past now

[akinsho]

LGTM now 👍🏿 thanks for the changes @matthis-k