Writing useful lua functions to my neovim

Intro

I used to have a very large vimrc but now, I decided to write my own init.lua, after writing almost everything essential I started to port my functions, things like the Preserve function, so I can delete trailing spaces without moving my cursor.

local M = {}

M.preserve = function(arguments)
    local arguments = string.format("keepjumps keeppatterns execute %q", arguments)
    -- local original_cursor = vim.fn.winsaveview()
    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
    vim.api.nvim_command(arguments)
    local lastline = vim.fn.line("$")
    -- vim.fn.winrestview(original_cursor)
    if line > lastline then
        line = lastline
    end
    vim.api.nvim_win_set_cursor({ 0 }, { line, col })
end

return M

After writing the above function you can do:

vim.cmd([[cnoreab cls Preserve]])
vim.cmd([[command! Preserve lua preserve('%s/\\s\\+$//ge')]])
vim.cmd([[command! Reindent lua preserve("sil keepj normal! gg=G")]])
vim.cmd([[command! BufOnly lua preserve("silent! %bd|e#|bd#")]])

Change file header helper

What about updating your file header every time you save, I mean, type:
:update<cr>?

--> :lua changeheader()
-- This function is called with the BufWritePre event (autocmd)
-- and when I want to save a file I use ":update" which
-- only writes a buffer if it was modified
M.changeheader = function()
    -- We only can run this function if the file is modifiable
    if not vim.api.nvim_buf_get_option(vim.api.nvim_get_current_buf(), "modifiable") then
        return
    end
    if vim.fn.line("$") >= 7 then
        os.setlocale("en_US.UTF-8") -- show Sun instead of dom (portuguese)
        time = os.date("%a, %d %b %Y %H:%M")
        M.preserve("sil! keepp keepj 1,7s/\\vlast (modified|change):\\zs.*/ " .. time .. "/ei")
    end
end

Next section you can see how the function above is triggered/associated with the BufWritePre event, changing automatically your file header where you can read: "Last Change:".

For you autocommands you can do:

-- autocommands
--- This function is taken from https://github.com/norcalli/nvim_utils
function nvim_create_augroups(definitions)
    for group_name, definition in pairs(definitions) do
        api.nvim_command('augroup '..group_name)
        api.nvim_command('autocmd!')
        for _, def in ipairs(definition) do
            local command = table.concat(vim.tbl_flatten{'autocmd', def}, ' ')
            api.nvim_command(command)
        end
        api.nvim_command('augroup END')
    end
end

local autocmds = {
    reload_vimrc = {
        -- Reload vim config automatically
        {"BufWritePost",[[$VIM_PATH/{*.vim,*.yaml,vimrc} nested source $MYVIMRC | redraw]]};
    };
    change_header = {
        {"BufWritePre", "*", "lua changeheader()"}
    };
    packer = {
        { "BufWritePost", "plugins.lua", "PackerCompile" };
    };
    terminal_job = {
        { "TermOpen", "*", [[tnoremap <buffer> <Esc> <c-\><c-n>]] };
        { "TermOpen", "*", "startinsert" };
        { "TermOpen", "*", "setlocal listchars= nonumber norelativenumber" };
    };
    restore_cursor = {
        { 'BufRead', '*', [[call setpos(".", getpos("'\""))]] };
    };
    save_shada = {
        {"VimLeave", "*", "wshada!"};
    };
    resize_windows_proportionally = {
        { "VimResized", "*", ":wincmd =" };
    };
    toggle_search_highlighting = {
        { "InsertEnter", "*", "setlocal nohlsearch" };
    };
    lua_highlight = {
        { "TextYankPost", "*", [[silent! lua vim.highlight.on_yank() {higroup="IncSearch", timeout=400}]] };
    };
    ansi_esc_log = {
        { "BufEnter", "*.log", ":AnsiEsc" };
    };
}

nvim_create_augroups(autocmds)
-- autocommands END

Squeeze blank lines

M.squeeze_blank_lines = function()
-- references: https://vi.stackexchange.com/posts/26304/revisions
    if vim.bo.binary == false and vim.opt.filetype:get() ~= "diff" then
        local old_query = vim.fn.getreg("/") -- save search register
        M.preserve("sil! 1,.s/^\\n\\{2,}/\\r/gn") -- set current search count number
        local result = vim.fn.searchcount({ maxcount = 1000, timeout = 500 }).current
        local line, col = unpack(vim.api.nvim_win_get_cursor(0))
        M.preserve("sil! keepp keepj %s/^\\n\\{2,}/\\r/ge")
        M.preserve("sil! keepp keepj %s/\\v($\\n\\s*)+%$/\\r/e")
        if result > 0 then
            vim.api.nvim_win_set_cursor({ 0 }, { (line - result), col })
        end
        vim.fn.setreg("/", old_query) -- restore search register
    end
end

map helper

-- map helper
local function map(mode, lhs, rhs, opts)
    local options = {noremap = true}
    if opts then options = vim.tbl_extend('force', options, opts) end
    vim.api.nvim_set_keymap(mode, lhs, rhs, options)
end

map('n', '<leader>d', ':lua delblanklines()<cr>')

Delete buffer or quit

The code below is in my utils.lua which is a lua module, so it has on its first line

local M = {}

and at the end

return M

It is mapped in my keymaps.lua to <leader>bd mnemonic to buffer delete and it runs some tests to determine if the file is modified, if it has a name and so on, in practice if you are in the last buffer it will close the neovim instance, in case of unsaved files it will ask you.

-- Esta função detecta se o buffer foi modificado
-- se o buffer tem nome roda um update
-- se não tem nome pergunta se quer salvar (perguntando também o nome)
-- o processo de salvamento do arquivo pode ser cancelado com Ctrl-c
-- ao final ele vai fechar o neovim se for o último buffer
-- caso contrário ele apenas fecha o buffer corrente

-- deleta o buffer se for o último buffer sai do nvim
M.bd_or_quit = function()
  if M.buf_modified() then
    local bufname = vim.api.nvim_buf_get_name(0) -- Obter o nome do buffer atual

    if bufname ~= "" then -- Se o buffer tiver nome
      vim.cmd("update!") -- Salvar as alterações no arquivo existente
    else -- Se o buffer não tiver nome
      -- Perguntar se deseja salvar
      local ok, response = pcall(vim.fn.confirm, "Deseja salvar o buffer?", "&Sim\n&Não", 2)
      if not ok or response ~= 1 then
           vim.cmd(M.get_listed_bufs() == 1 'qa!' or 'bd!') -- Fechar o buffer sem salvar
        return -- Cancelar se o usuário não quiser salvar
      end

      -- Loop para obter o nome do arquivo
      local filename
      repeat
        local ok
        ok, filename = pcall(vim.fn.input, "Digite o nome do arquivo (ou Ctrl+C para cancelar): ")
        if not ok then
          return -- Cancelar se o usuário pressionar Ctrl+C
        end
      until filename ~= ""

      -- Verificar se o arquivo já existe e perguntar se deseja sobrescrever
      local file_exists = vim.fn.filereadable(filename)
      if file_exists == 1 then -- Se o arquivo já existe
        local ok, response = pcall(vim.fn.confirm, "O arquivo já existe. Deseja sobrescrever?", "&Sim\n&Não", 2)
        if not ok or response ~= 1 then
          return -- Cancelar se o usuário não confirmar a sobrescrita
        end
      end

      -- Salvar o arquivo com o nome fornecido
      vim.cmd("w " .. filename)
    end
  end

  -- Verificar se é o último buffer listado
  if M.get_listed_bufs() == 1 then
    vim.cmd("qa!") -- Sair sem salvar se for o último buffer
  else
    vim.cmd("bd") -- Deletar o buffer
    vim.cmd("bn") -- Ir para o próximo buffer
  end
end

-- verifica se o buffer foi modificado
M.buf_modified = function(buf)
  local buf = buf or vim.api.nvim_get_current_buf()
  return vim.api.nvim_buf_get_option(buf, 'modified')
end

-- retorna a quantidade de buffers listáveis
M.get_listed_bufs = function()
  local listed_buffers = vim.tbl_filter(function(bufnr)
    return vim.api.nvim_buf_get_option(bufnr, "buflisted")
  end, vim.api.nvim_list_bufs())
  return #listed_buffers
end

This article can change/grow a little bit

References:

The main source I have used was this post on neovim.discourse.group