Continuing the rewrite of my Neovim config described in this post, I decided to get ride of nvim-lspconfig. Indeed, since version 0.8 Neovim offers some convenient functions and autocommands to start an LSP server with predefined mappings which can be made aware of available server capabilities. This is well explained by Mathias Fußenegger. I came across his post some months ago and forgot about it. And then I found a similar discussion on another blog post. So why not remove nvim-lspconfig and define LSP settings in my ftplugin directory. This way, I get all vimL stuff in after/ftplugin, with appropriate guards for nvim and executable that I use for linting and formatting, and all Lua stuff in my init.lua and ftplugin.
This solved many problems at the same time. First, nvim-lspconfig doesn’t let me loop over a series of server so easily. For instance, the following loop must account for specific servers that need additional settings (e.g., clangd to get background indexing, etc.) or slight modification from the default config (e.g., racket_langserver which is defined for racket and scheme filetype – we really don’t want the second one):
local servers = {
...
}
for _, lsp in ipairs(servers) do
nvim_lsp[lsp].setup({
on_attach = on_attach(),
capabilities = capabilities,
})
end
Second, there are some edge cases, which I think are related to the definition of the project root directory for LSP that really need a root_dir (e.g., clojure_lsp), meaning that the server will start if I open a file with the associated filetype directly but not after a simple vim . from the root directory. On the other hand, nvim-lspconfig provides some interesting functions to define the root directory of a project (pending the minor issue just mentioned) or to query the server state, and to restart it if required.
So, how does the in-built facilities of Neovim solve my concerns? I can now isolate the logic of writing specific settings for each LSP in separate files that live in ftplugin, while defining common guarded features relevant to all LSPs. Here is a simple example in the case of Python (I use pyright in this case):
-- ftplugin/python.lua
local config = {
name = "pyright",
cmd = { "pyright-langserver", "--stdio" },
root_dir = vim.fs.dirname(
vim.fs.find({ "setup.py", "pyproject.toml", "setup.cfg", "requirements.txt", ".git" }, { upward = true })[1]
),
}
vim.lsp.start(config, {
reuse_client = function(client, conf)
return (
client.name == conf.name
and (
client.config.root_dir == conf.root_dir
or (conf.root_dir == nil and vim.startswith(api.nvim_buf_get_name(0), "/usr/lib/python"))
)
)
end,
})
local augroup = vim.api.nvim_create_augroup("PythonFormatting", {})
vim.api.nvim_clear_autocmds({ group = augroup, buffer = bufnr })
vim.api.nvim_create_autocmd({ "BufWritePre" }, {
group = augroup,
buffer = bufnr,
callback = function()
vim.api.nvim_command("call FormatFile()")
end,
})
The last block allow to complement pyright with autoformatting thanks to a custom VimL function, inspired from this post, that checks the value of formatprg associated with that filetype. This is defined in after/ftplugin, which further allows me to use gq whenever I want.
" after/ftplugin/python.vim
setlocal formatprg=python3\ -m\ macchiato
" setlocal formatprg=black\ -q\ 2>/dev/null\ --stdin-filename\ %\ -
Then I defined mappings and an autocommand in my init.lua file:
vim.api.nvim_create_autocmd("LspAttach", {
callback = function(args)
local client = vim.lsp.get_client_by_id(args.data.client_id)
local augroup = vim.api.nvim_create_augroup("LspFormatting", {})
vim.keymap.set("i", "<C-k>", vim.lsp.buf.signature_help, { buffer = args.buf })
vim.keymap.set("n", "K", vim.lsp.buf.hover, { buffer = args.buf })
vim.keymap.set("n", "gd", "<cmd>lua require('fzf-lua').lsp_definitions({ jump_to_single_result = true })<cr>")
vim.keymap.set("n", "gr", "<cmd>lua require('fzf-lua').lsp_references()<cr>")
if client.server_capabilities.codeActionProvider then
vim.keymap.set("n", "z=", "<cmd>lua require('fzf-lua').lsp_code_actions()<cr>")
end
if client.server_capabilities.renameProvider then
vim.keymap.set("n", "zr", vim.lsp.buf.rename, { buffer = args.buf })
end
if client.server_capabilities.documentSymbolProvider then
vim.keymap.set("n", "go", "<cmd>lua require('fzf-lua').lsp_document_symbols()<cr>")
end
if client.server_capabilities.workspaceSymbolProvider then
vim.keymap.set("n", "gO", "<cmd>lua require('fzf-lua').lsp_workspace_symbols()<cr>")
end
if client.server_capabilities.codeLensProvider then
vim.api.nvim_create_autocmd({ "CursorMoved " }, {
callback = function()
vim.lsp.codelens.refresh()
end,
})
vim.keymap.set("n", "z!", vim.lsp.codelens.run, { buffer = args.buf, silent = true })
end
if client.supports_method("textDocument/formatting") then
-- vim.api.nvim_buf_create_user_command(bufnr, 'Format', function() vim.lsp.buf.format() end)
vim.keymap.set("n", "g=", vim.lsp.buf.format, { buffer = args.buf })
vim.api.nvim_clear_autocmds({ group = augroup, buffer = bufnr })
vim.api.nvim_create_autocmd({ "BufWritePre " }, {
group = augroup,
buffer = bufnr,
callback = function()
vim.lsp.buf.format({ async = false })
end,
})
end
end,
})
Note that I use fzf-lua as a fuzzy picker for many things in this case.
Needless to say, my Neovim starts even faster now.
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