[mini.files] Attempt to constrain multiple cursors for mini.files

[celeste3z]

  local function constrain_cursor(win, buf)
    if not vim.api.nvim_win_is_valid(win) then return end
    if not vim.api.nvim_buf_is_valid(buf) then return end
    local ns = vim.api.nvim_create_namespace("nvim.multicursor")
    local extmarks = vim.api.nvim_buf_get_extmarks(buf, ns, 0, -1)
    if #extmarks == 0 then return end
    for _, e in ipairs(extmarks) do
      local id, r, c = e[1], e[2], e[3] ---@type integer, integer, integer
      local line = vim.api.nvim_buf_get_lines(buf, r - 1, r, false)[1]
      if line then
        local _, name_start = line:match("^/%d+/().-()/")
        if name_start and name_start > c then
          vim.api.nvim_buf_set_extmark(buf, ns, r, name_start --[[@as integer]], { id = id })
        end
      end
    end
  end

  vim.api.nvim_create_autocmd("User", {
    pattern = "MiniFilesWindowUpdate",
    callback = function(ev) constrain_cursor(ev.data.win_id, ev.data.buf_id) end,
  })

To be honest, I'm not sure whether it's completely correct, I'm just sharing it. 😄

[echasnovski]

Thanks for sharing!

After a quick glance, there is nothing immediately questionable in the code. There might be some issues with multicursor visual selection, but that probably relies too much on the internals of multicursor implementation.

---

Note to self: it is probably a good idea to do this in 'mini.files' directly after the Neovim 0.13 is released.

[echasnovski]

@celeste3z, this behavior ("constrain extra cursors the same as main cursor") should now be the part of the main branch. Plus some other adjustments (clear multicursor after synchronization, as they get pushed anyway after setting lines).

So I'll close this. Thanks for bringing the attention to this use case!