rice/nvim/plugins/bufferline.lua

require('bufferline').setup {
  options = {
    -- numbers = function(opts)
    --   return string.format("%s", opts.id)
    -- end,
    numbers = function(opts)
      return ""
    end,
    -- number_style = "superscript" | "subscript" | "" | { "none", "subscript" }, -- buffer_id at index 1, ordinal at index 2
    -- number_style = "none",
    close_command = "bdelete! %d",       -- can be a string | function, see "Mouse actions"
    right_mouse_command = "bdelete! %d", -- can be a string | function, see "Mouse actions"
    left_mouse_command = "buffer %d",    -- can be a string | function, see "Mouse actions"
    middle_mouse_command = nil,          -- can be a string | function, see "Mouse actions"
    -- NOTE: this plugin is designed with this icon in mind,
    -- and so changing this is NOT recommended, this is intended
    -- as an escape hatch for people who cannot bear it for whatever reason
    indicator_icon = '▎',
    buffer_close_icon = '',
    modified_icon = '●',
    close_icon = '',
    left_trunc_marker = '',
    right_trunc_marker = '',
    --- name_formatter can be used to change the buffer's label in the bufferline.
    --- Please note some names can/will break the
    --- bufferline so use this at your discretion knowing that it has
    --- some limitations that will *NOT* be fixed.
    name_formatter = function(buf)  -- buf contains a "name", "path" and "bufnr"
      -- remove extension from markdown files for example
      if buf.name:match('%.md') then
        return vim.fn.fnamemodify(buf.name, ':t:r')
      end
    end,
    max_name_length = 18,
    max_prefix_length = 15, -- prefix used when a buffer is de-duplicated
    tab_size = 18,
    -- diagnostics = false | "nvim_lsp" | "coc",
    diagnostics = "coc",
    diagnostics_update_in_insert = false,
	diagnostics_indicator = function(count, level, diagnostics_dict, context)
      local s = " "
      for e, n in pairs(diagnostics_dict) do
        local sym = e == "error" and " "
          or e == "hint" and " "
          or (e == "warning" and " " or "" )
        s = s .. n .. sym
      end
      return s
    end,
    custom_filter = function(buf_number, buf_numbers)
      -- filter out filetypes you don't want to see
      if vim.bo[buf_number].filetype ~= "<i-dont-want-to-see-this>" then
        return true
      end
      -- filter out by buffer name
      if vim.fn.bufname(buf_number) ~= "<buffer-name-I-dont-want>" then
        return true
      end
      -- filter out based on arbitrary rules
      -- e.g. filter out vim wiki buffer from tabline in your work repo
      if vim.fn.getcwd() == "<work-repo>" and vim.bo[buf_number].filetype ~= "wiki" then
        return true
      end
      -- filter out by it's index number in list (don't show first buffer)
      if buf_numbers[1] ~= buf_number then
        return true
      end
    end,
    -- offsets = {{filetype = "NvimTree", text = "File Explorer" | function , text_align = "left" | "center" | "right"}},
    -- offsets = text_align = "left" | "center" | "right"}},
    show_buffer_icons = true,
    show_buffer_close_icons = true,
    show_close_icon = false,
    show_tab_indicators = true,
    persist_buffer_sort = false, -- whether or not custom sorted buffers should persist
    -- can also be a table containing 2 custom separators
    -- [focused and unfocused]. eg: { '|', '|' }
    -- separator_style = "slant" | "thick" | "thin" | { 'any', 'any' },
    separator_style = "thick",
    enforce_regular_tabs = false,
    always_show_bufferline = true,
    -- sort_by = 'id' | 'extension' | 'relative_directory' | 'directory' | 'tabs' | function(buffer_a, buffer_b)
    sort_by = 'id',
  }
}