Main: how to know when install is done?

[cameronr]

I've transitioned from master to main and I'm trying to restore the auto-start/auto-install behavior from master. I have this autocmd:

vim.api.nvim_create_autocmd({ 'Filetype' }, {
  callback = function(event)
    local ignored_fts = {
      'snacks_dashboard',
      'prompt', -- bt: snacks_picker_input
    }

    if vim.bo[event.buf].bt == 'nofile' then return end
    if vim.tbl_contains(ignored_fts, event.match) then return end

    local ok, result = pcall(vim.treesitter.start, event.buf)
    if not ok then
      local ft = vim.bo[event.buf].ft

      -- need to require treesitter here so get_lang works for all langs
      local nvim_treesitter = require('nvim-treesitter')
      local lang = vim.treesitter.language.get_lang(ft)

      if lang then
        if not nvim_treesitter.install({ lang }) then
          vim.notify(result .. '\nbt: ' .. vim.bo[event.buf].bt)
          return
        end
      end

      ok, result = pcall(vim.treesitter.start, event.buf)
      if not ok then return end
    end

    vim.bo.indentexpr = "v:lua.require'nvim-treesitter'.indentexpr()"
    vim.wo.foldexpr = 'v:lua.vim.treesitter.foldexpr()'
  end,
})

It works except that the file isn't reparsed when parser is installed (doing :e or re-setting the filetype will trigger reparsing). It seems like the call to install starts the tasks asynchronously and returns before they're complete. Is there a way to tell when install is done (e.g. maybe a way to pass in a callback or a way to wait for the task to complete)?

[cameronr]

Doing more testing, I noticed there's an additional wrinkle: before require('nvim-treesitter'), the return from vim.treesitter.start(event.buf)fails if the parser is not installed. After requiring it,vim.treesitter.start(event.buf)` succeeds even if the parser isn't installed. For example:

vim.api.nvim_create_autocmd({ 'Filetype' }, {
  callback = function(event)
    local ignored_fts = {
      'snacks_dashboard',
      'snacks_input',
      'prompt', -- bt: snacks_picker_input
    }

    if vim.bo[event.buf].bt == 'nofile' then return end
    if vim.tbl_contains(ignored_fts, event.match) then return end

    local ok, result = pcall(vim.treesitter.start, event.buf)
    vim.notify('ok: ' .. vim.inspect(ok) .. ' result: ' .. vim.inspect(result))
    local nvim_treesitter = require('nvim-treesitter')
    ok, result = pcall(vim.treesitter.start, event.buf)
    vim.notify('nvim-treesitter: ok: ' .. vim.inspect(ok) .. ' result: ' .. vim.inspect(result))
  end,
})

For a ft that's not installed (i was testing with sshconfig), that first call to start will fail but the second one will succeed:

13:52   INFO ok: false result: '.../neovim/0.11.3/share/nvim/runtime/lua/vim/treesitter.lua:431:
              Parser could not be created for buffer 1 and language "sshconfig"'
13:52   INFO nvim-treesitter: ok: true result: nil

So how can I tell if a parser is actually installed or not?

Or maybe I should just always be calling install?

[cameronr]

After a bit more noodling, this is what I have and it seems to work

vim.api.nvim_create_autocmd({ 'Filetype' }, {
  callback = function(event)
    local ignored_fts = {
      'snacks_dashboard',
      'snacks_input',
      'prompt', -- bt: snacks_picker_input
    }

    if vim.tbl_contains(ignored_fts, event.match) then return end

    -- make sure nvim-treesitter is loaded
    local nvim_treesitter = require('nvim-treesitter')

    local ft = vim.bo[event.buf].ft
    local lang = vim.treesitter.language.get_lang(ft)
    nvim_treesitter.install({ lang }):await(function(err)
      if err then
        vim.notify('Treesitter install error for ft: ' .. ft .. ' err: ' .. err)
        return
      end

      pcall(vim.treesitter.start, event.buf)
      vim.bo.indentexpr = "v:lua.require'nvim-treesitter'.indentexpr()"
      vim.wo.foldexpr = 'v:lua.vim.treesitter.foldexpr()'
    end)
  end,
})

If there's a better way to see if a parser is installed vs just always calling install, please let me know

[cameronr]

Whoops, just noticed I posted this in textobjects