Neovim: fold code with `foldmethod=syntax` or `foldmethod=expr` depending on Tree-sitter

Question

I've just fresh-installed LazyVim and I'm having troubles configuring code folding to my liking.

For the languages for which I have no nvim-treesitter parser installed I would like to use :set foldmethod=syntax (presumably Neovim already knows how to parse these languages at a basic level).
On the other hand, for the languages for which I have a nvim-treesitter parser installed and configured I would like to use :set foldmethod=expr foldexpr=nvim_treesitter#foldexpr().

The reason for this is that in both circumstances if I use the opposite configuration then code folding will not work at all.

My idea is to default to :set foldmethod=syntax and have an autocommand switch it to expr when opening a buffer with nvim-treesitter support, however I have no idea how to achieve that (I don't know what event to listen to and how to detect whether a nvim-treesitter parser gets loaded for the current buffer). Maybe there is some other way to achieve this, by directly configuring nvim-treesitter to do the switching; I don't know.

Does anybody have a solution?

neovim/vi/vim questions should be asked on vi.stackexchange.com Please delete this and ask over there. — Rob
– Rob, Commented Feb 15, 2024 at 22:32

mattbh · Accepted Answer · 2024-02-18 02:06:20Z

8

In your LazyVim config, under lua/config/autocmds.lua, you can add:

vim.api.nvim_create_autocmd({ "FileType" }, {
  callback = function()
    if require("nvim-treesitter.parsers").has_parser() then
      vim.opt.foldmethod = "expr"
      vim.opt.foldexpr = "nvim_treesitter#foldexpr()"
    else
      vim.opt.foldmethod = "syntax"
    end
  end,
})

This follows the general format recommended in LazyVim's tips section.

Note that, as recommended in the nvim-treesitter README, you may also want to set this elsewhere:

set nofoldenable   " Disable folding at startup.

... though I found it unnecessary, as files open without folds anyway in my LazyVim config.

Note that this won't trigger for new, unnamed buffers. If you wanted to handle that explicitly you could trying handling the BufEnter event instead of FileType, or have a look at other event types via :help events inside Neovim.

edited Feb 18, 2024 at 2:06

answered Feb 15, 2024 at 10:13

mattbh

5,5052 gold badges30 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Neovim: fold code with `foldmethod=syntax` or `foldmethod=expr` depending on Tree-sitter

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related