Check if there are non-empty or named buffers open

Question

When closing Neovim, I'd like to store the session, but only if there are any files open. If I only have the dashboard open, or an empty unsaved buffer, I want to skip this step. So, I need a way to check if this is the case.

So-far

I thought I can just loop through the buffers and then through the lines of each buffer, like so:

function are_all_buffers_unnamed_and_empty()
  for _, bufnr in ipairs(vim.api.nvim_list_bufs()) do
    local bufname = vim.api.nvim_buf_get_name(bufnr)
    if bufname ~= '' then
      return false -- If any buffer has a name, return false
    end
    local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
    if #lines > 1 or (#lines == 1 and #lines[1] > 0) then
      return false -- If any buffer has content, return false
    end
  end
  return true -- All buffers are unnamed and empty
end

Problem

This almost works, but:

If there is a notification showing (i.e., drawn on top of the buffer), this is also looped over, and the function returns false. For example, in this case:

Is there a way to exclude these "trivial" buffers such as file explorers, dashboards, and notifications?

Answer 1

I would us the filetype and the readonly option to determine if the buffer is relevant:

function are_all_buffers_unnamed_and_empty()
  for _, bufnr in ipairs(vim.api.nvim_list_bufs()) do
    local bufname = vim.api.nvim_buf_get_name(bufnr)
    if bufname ~= '' then
      return false -- If any buffer has a name, return false
    end

    local readonly = vim.api.nvim_buf_get_option(bufnr, 'readonly'))
    if readonly then
      return false
    end

    local listed = vim.api.nvim_buf_get_option(bufnr, 'buflisted'))
    if not listed then
      return false
    end

    local buftype = vim.api.nvim_buf_get_option(bufnr, 'buftype'))
    if buftype == 'terminal' then
      return false
    end
    if buftype == "quickfix" then
      return false
    end

    local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
    if #lines > 1 or (#lines == 1 and #lines[1] > 0) then
      return false -- If any buffer has content, return false
    end
  end
  return true -- All buffers are unnamed and empty
end

Answer 2

I ended up using this:

local function no_buffers_worth_saving()
  for _, bufnr in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_get_option(bufnr, 'buflisted') and not vim.api.nvim_buf_get_option(bufnr, 'readonly') then -- disregard unlisted buffers
      if vim.api.nvim_buf_get_name(bufnr) ~= '' then
        return false -- there is a buffer with a name
      end
      local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
      if #lines > 1 or (#lines == 1 and #lines[1] > 0) then
        return false -- there is a buffer with content
      end
    end
  end
  return true -- there are no listed, writable, named, nonempty buffers
end

(I renamed the function to focus on its use and not its implementation.)