Help: Remap Ctrl-n to "switch to n-th buffer"

[tf42src]

I have this code in my keymaps.lua

local defaults = { noremap = true, silent = true }

-- function to switch to the nth buffer
_G.goto_buffer = function(n)
  return function()
    vim.api.nvim_command('buffer ' .. n)
  end
end

-- map Ctrl-1 to Ctrl-9 to switch to buffer 1 to 9
for i = 1, 9 do
  vim.api.nvim_set_keymap('n', '<C-' .. i .. '>', ':lua goto_buffer(' .. i .. ')()<CR>', defaults)
end

The function is called when Ctrl-n is pressed, but the buffer numbers are not sequential. Executing :buffers shows me my four files have the buffer ids: 3, 22, 75, 77.

How can I remap my keys so that I can easily jump to a specific buffer using Ctrl-n ?

[dpetka2001]

Something like the following could work

local buffers = {}
for _, buf in ipairs(vim.api.nvim_list_bufs()) do
  if vim.api.nvim_buf_is_valid(buf) and vim.bo[buf].buftype == "" then
    table.insert(buffers, buf)
  end
end

for k, v in ipairs(buffers) do
  vim.keymap.set("n", "<M-" .. k .. ">", "<cmd>buffer " .. v .. "<cr>", { desc = "go to buffer" })
end

But I personally prefer setting a keymap with Bufferline (if you use it) to do the same

vim.keymap.set("n", "<leader>bb", function()
  require("bufferline").pick()
end, { desc = "Pick buffer" })

[tf42src]

I have added the bufferline solution. Will give it a try, it seems quite neat.

Nevertheless, it would be great to get Ctrl-n working as well (I assume I will just be faster - and I don't want to give up).

The solution you posted doesn't seem to work out of the box. I assume the for loop needs to run inside a function? (because the number of buffers changes all the time). I got it working with a mix of your code and mine:

_G.goto_buffer = function(n)
  local counter = 1
  for _, buf in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_is_valid(buf) and vim.bo[buf].buftype == "" then
      if counter == n then
        vim.api.nvim_command("buffer " .. buf)
        break
      end
      counter = counter + 1
    end
  end
end

-- map Ctrl-1 to Ctrl-9 to switch to buffer 1 to 9
for i = 1, 9 do
  vim.api.nvim_set_keymap("n", "<C-" .. i .. ">", ":lua goto_buffer(" .. i .. ")()<CR>", defaults)
end

It works. The only annoying part left is the following error message (which does not occur if I type :lua goto_buffer(1)). Do I need to return something from the function?

[tf42src]

I am struggling to understand what nvim_list_bufs() does based on the documentation. What is a "buffer handle"? I am asking because replacing the wildcard in the loop with counter didn't have the same result as adding and incrementing the counter manually.

Edit:
Seems there are buffers which get filtered out in the if-clause and hence I cannot use the ipairs index.

[dpetka2001]

A buffer handle is the the buffer id of each buffer. When you do :buffers you get some numbers and partial buffer names. Those numbers are the buffer ids/handlers.

[dpetka2001]

I put the following in ~/.config/nvim/lua/config/autocmds.lua and it seems to do what you want

vim.api.nvim_create_autocmd({ "BufReadPost", "BufNewFile" }, {
  group = vim.api.nvim_create_augroup("test_buffers", {}),
  desc = "test buffers",
  callback = function()
    local buffers = {}
    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
      if vim.api.nvim_buf_is_valid(buf) and vim.bo[buf].buftype == "" then
        table.insert(buffers, buf)
      end
    end

    for k, v in ipairs(buffers) do
      vim.keymap.set("n", "<M-" .. k .. ">", "<cmd>buffer " .. v .. "<cr>", { desc = "go to buffer" })
    end
  end,
})

Test it out.

[dpetka2001]

Still I believe this is not needed with bufferline.pick. I just tested it for educational purposes.

[tf42src]

I put the following in ~/.config/nvim/lua/config/autocmds.lua and it seems to do what you want

vim.api.nvim_create_autocmd({ "BufReadPost", "BufNewFile" }, {
  group = vim.api.nvim_create_augroup("test_buffers", {}),
  desc = "test buffers",
  callback = function()
    local buffers = {}
    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
      if vim.api.nvim_buf_is_valid(buf) and vim.bo[buf].buftype == "" then
        table.insert(buffers, buf)
      end
    end

    for k, v in ipairs(buffers) do
      vim.keymap.set("n", "<M-" .. k .. ">", "<cmd>buffer " .. v .. "<cr>", { desc = "go to buffer" })
    end
  end,
})

Test it out.

Works like a charm! And I also learned about auto commands, thank you!

For potential others, need to replace M- with C- to use ctrl instead of modifier (alt).

[tf42src]

@dpetka2001 what is the autocmd hook for "move buffer" (e.g. <leader>[B)? ;)

Edit:
Actually I don't think this would work either as the IDs remain the same. So the question would be how do I get the current buffer position in the list of buffers?

[tf42src]

I have added the bufferline solution. Will give it a try, it seems quite neat.

Nevertheless, it would be great to get Ctrl-n working as well (I assume I will just be faster - and I don't want to give up).

The solution you posted doesn't seem to work out of the box. I assume the for loop needs to run inside a function? (because the number of buffers changes all the time). I got it working with a mix of your code and mine:

_G.goto_buffer = function(n)
  local counter = 1
  for _, buf in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_is_valid(buf) and vim.bo[buf].buftype == "" then
      if counter == n then
        vim.api.nvim_command("buffer " .. buf)
        break
      end
      counter = counter + 1
    end
  end
end

-- map Ctrl-1 to Ctrl-9 to switch to buffer 1 to 9
for i = 1, 9 do
  vim.api.nvim_set_keymap("n", "<C-" .. i .. ">", ":lua goto_buffer(" .. i .. ")()<CR>", defaults)
end

It works. The only annoying part left is the following error message (which does not occur if I type :lua goto_buffer(1)). Do I need to return something from the function?

To solve the error in the screenshot, I had to remove the extra () after the goto_buffer call, before the <CR>, like so:
vim.api.nvim_set_keymap("n", "<C-" .. i .. ">", ":lua goto_buffer(" .. i .. ")<CR>", defaults)