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Attached A Neovim Buffer To An LSP Based Off File Extension

I'm working on an LSP to use with Neopolitan in Neovim. The first hurdle was figuring out how to attach a file to the LSP. This is how I'm doing it.

Code

vim.api.nvim_create_autocmd("BufReadPost", {
  pattern = "*.tmp",
  group = vim.api.nvim_create_augroup("LSPTestGroup", { clear = true }),
  callback = function() 
    vim.lsp.start({
      name = 'neopolitan',
      cmd = {'/Users/alan/workshop/neopolitan-lsp/target/debug/nrs-language-server'},
      root_dir = vim.fs.dirname(vim.fs.find({'Cargo.toml'}, { upward = true })[1]),
    })
  end,
})

Notes

  • "pattern" is for the file pattern. I'm using "*.tmp" for demo purposes.

  • The "group" sets an autogroup that clears each time things run to prevent multiple instances of the command getting installed

  • The "callback" is what run when the autocmd event triggers

  • vim.lsp.start() - starts an LSP client or reuses one with the same name if there's one already running. Then it attaches the current buffer to it

  • I'm not sure if "root_dir" is necessary. LSPs do stuff with projects, but I don't need that for my stuff. TBD on that

  • I think there are other plugins like "mason" that deal with this stuff for existing LSPs and I'm sure I could figure out how to get what I'm working on set up with them at some point. For now, this gets me started

  • It's also possible there are some server connection settings that can get things to work automatically, but it didn't start for me out of the box with tower-lsp and tower-lsp-boilerplate

References