Smart Tabline (don't update tabline with non-standard buffer names)

[n-crespo]

I hate seeing irrelevant file names in my tabline. Ideally, I want that name to change as little as possible, and only when I switch to an actual buffer, not a floating window or terminal. With this config, I can ensure the "tabs" component doesn't get changed when you focus a terminal, floating window, or prompt.

I also built in a way to improve renaming tabs that retains their names in global variables so they can be preserved between sessions (mapped this to R but you could even edit it to some other : command just like :LualineRenameTab). Add the following to your config to preserve globals:

vim.o.sessionoptions = vim.o.sessionoptions .. ",globals"

I also increased the default tabline refresh rate a ton to avoid redundant refreshing, so I added explicit refresh calls in all keymaps that manipulate the tabline.

local NO_NAME = "[No Name]"

-- make sure to refresh lualine when needed
vim.api.nvim_create_autocmd({ "TabNew", "TabEnter", "TabClosed", "WinEnter", "BufWinEnter" }, {
  callback = function()
    require("lualine").refresh({ scope = "all", place = { "tabline" } }) 
  end,
})

-- utility function, returns true if buffer with specified
-- buf/filetype should be ignored by the tabline or not
local function ignore_buffer(bufnr)
  local ignored_buftypes = { "prompt", "nofile", "terminal", "quickfix" }
  local ignored_filetypes = { "snacks_picker_preview" }

  local filetype = vim.bo[bufnr].filetype
  local buftype = vim.bo[bufnr].buftype
  local name = vim.api.nvim_buf_get_name(bufnr)

  return vim.tbl_contains(ignored_buftypes, buftype) or vim.tbl_contains(ignored_filetypes, filetype) or name == ""
end

-- Get buffer name, using alternate buffer or last visited buffer if necessary
local function get_buffer_name(bufnr, context)
  local function get_filename(buf)
    return vim.fn.fnamemodify(vim.api.nvim_buf_get_name(buf), ":t")
  end

  -- rename tabs with <leader>r and ensure globals persist between sessions with:
  -- vim.o.sessionoptions = vim.o.sessionoptions .. ",globals"
  local custom_name = vim.g["Lualine_tabname_" .. context.tabnr]
  if custom_name and custom_name ~= "" then
    return custom_name
  end

  -- this makes empty buffers/tabs show "[No Name]"
  if vim.api.nvim_buf_get_name(bufnr) == "" and vim.bo[bufnr].buflisted then
    return NO_NAME
  end

  if ignore_buffer(bufnr) then
    local alt_bufnr = vim.fn.bufnr("#")
    if alt_bufnr ~= -1 and alt_bufnr ~= bufnr and not ignore_buffer(alt_bufnr) then
      -- use name of alternate buffer
      return get_filename(alt_bufnr)
    end

    -- Try to use the name of a different window in the same tab
    local win_ids = vim.api.nvim_tabpage_list_wins(0)
    for _, win_id in ipairs(win_ids) do
      local found_bufnr = vim.api.nvim_win_get_buf(win_id)
      if not ignore_buffer(found_bufnr) then
        local name = get_filename(found_bufnr)
        return name ~= "" and name or NO_NAME
      end
    end
    return NO_NAME
  end

  return get_filename(bufnr)
end

return {
  "nvim-lualine/lualine.nvim",
  opts = function()
    local opts = {
      options = {
        always_show_tabline = false, -- only show tabline when >1 tabs
        refresh = {
          tabline = 10000,
        },
      },
      tabline = {
        lualine_a = {
          {
            "tabs",
            show_modified_status = false,
            max_length = vim.o.columns - 2,
            mode = 1,
            padding = 1,
            tabs_color = {
              -- Same values as the general color option can be used here.
              active = "TabLineSel", -- Color for active tab.
              inactive = "TabLineFill", -- Color for inactive tab.
            },

            fmt = function(name, context)
              local buflist = vim.fn.tabpagebuflist(context.tabnr)
              local winnr = vim.fn.tabpagewinnr(context.tabnr)
              local bufnr = buflist[winnr]

              -- hard code 'scratch' name for Snacks scratch buffers
              if name:find(".scratch") then
                name = "scratch"
              else
                name = get_buffer_name(bufnr, context)
              end

              -- include tabnr only if # of tabs > 3
              return ((vim.fn.tabpagenr("$") > 3) and (context.tabnr .. " ") or "") .. name
            end,
          },
        },
      },
    }
    return opts
  end,
  keys = {
    {
      "<leader>r",
      function()
        local current_tab = vim.fn.tabpagenr()
        vim.ui.input({ prompt = "New Tab Name: " }, function(input)
          if input or input == "" then
            vim.g["Lualine_tabname_" .. current_tab] = input
            require("lualine").refresh({ scope = "all", place = { "tabline" } })
          end
        end)
      end,
    },
    {
      "<A-,>",
      function()
        local current_tab = vim.fn.tabpagenr()
        if current_tab == 1 then
          vim.cmd("tabmove")
        else
          vim.cmd("-tabmove")
        end
          require("lualine").refresh({ scope = "all", place = { "tabline" } })
      end,
      desc = "Move Tab Left",
    },
    {
      "<A-;>",
      function()
        local current_tab = vim.fn.tabpagenr()
        if current_tab == vim.fn.tabpagenr("$") then
          vim.cmd("0tabmove")
        else
          vim.cmd("+tabmove")
        end
        require("lualine").refresh({ scope = "all", place = { "tabline" } })
      end,
      desc = "Move Tab Right",
    },
  },
}

Let me know if there's any obvious ways to optimize this (faster rending logic is ideal since refreshing can happen very frequently) or just general feedback!