mfussenegger / nvim-lsp-compl

A fast and asynchronous auto-completion plugin for Neovim, focused on LSP.

nvim-lsp-compl

A fast and asynchronous auto-completion plugin for Neovim (latest stable and nightly), focused on LSP.

For Neovim 0.5.1 support, checkout ad95138d56b7c84fb02e7c7078e8f5e61fda4596.

Motivation

Why another one?

I wrote the initial code for this within my dotfiles long before plugins like nvim-compe or nvim-cmp popped up and tuned it over time to accommodate my workflow.

There have been some voices looking for something smaller than the alternatives, so I decided to extract the code from my dotfiles and make it re-usable for others.

Features

• Automatically triggers completion on trigger characters advocated by the language server
• Automatically triggers signature help on characters advocated by the language server
• Apply additional text edits (Used to resolve imports and so on)
• Supports lazy resolving of additional text edits if the language server has the capability
• Optionally supports server side fuzzy matching
• Optionally supports LSP snippet expansion if vim.snippet is available, LuaSnip or vsnip is installed or a custom snippet-applier is registered

If you need anything else, you better use one of the others.

If you want additional completion sources you'd need to implement a language server. A full blown language server would have the advantage that other editors can benefit too, but if you'd like to use Neovim functionality, you could create a in-process Lua language server.

Opinionated behaviors:

• Snippets are only expanded via explicit opt-in
• The word in the completion candidates is tuned to exclude parenthesis and arguments, unless you use the snippet expansion.

Non-Goals

• Feature parity with nvim-compe

Installation

• Install Neovim (latest stable or nightly)
• Install nvim-lsp-compl like any other plugin
  • git clone https://github.com/mfussenegger/nvim-lsp-compl.git ~/.config/nvim/pack/plugins/start/nvim-lsp-compl
  • If using vim-plug: Plug 'mfussenegger/nvim-lsp-compl'
  • If using packer.nvim: use 'mfussenegger/nvim-lsp-compl'

Configuration

You need to call the attach method when the language server clients attaches to a buffer.

If you're using lspconfig you could do this like this:

lua require'lspconfig'.pyls.setup{on_attach=require'lsp_compl'.attach}

If you want to utilize server side fuzzy completion, you would call it like this:

lua require'lspconfig'.pyls.setup{
  on_attach = function(client, bufnr)
    require'lsp_compl'.attach(client, bufnr, { server_side_fuzzy_completion = true })
  end,
}

To expand snippets you need to extend the client capabilities. In the config for vim.lsp.start (See :help lsp-quickstart):

local config = {
    capabilities = vim.tbl_deep_extend(
        'force',
        vim.lsp.protocol.make_client_capabilities(),
        require('lsp_compl').capabilities()
    ),
}

And explicitly accept a completion candidate:

vim.keymap.set('i', '<CR>', function()
  return require('lsp_compl').accept_pum() and '<c-y>' or '<CR>'
end, { expr = true })

Currently snippet expansion order:

• LuaSnip if loaded
• vim.snippet
• LuaSnip again, this time trying to load it.
• vim-vsnip

You can override the expand_snippet function to use a different snippet engine:

require('lsp_compl').expand_snippet = vim.fn['vsnip#anonymous']

Or

require('lsp_compl').expand_snippet = require('luasnip').lsp_expand

The function takes a single argument - the snippet - and is supposed to expand it.

FAQ

Can I disable the automatic signature popup?

Yes, if you set the triggerCharacters of the server to an empty table:

on_attach = function(client, bufnr)
  if client.server_capabilities.signatureHelpProvider then
    client.server_capabilities.signatureHelpProvider.triggerCharacters = {}
  end
  require'lsp_compl'.attach(client, bufnr)
end

Can I customize the trigger characters for completion?

Yes, if you override the triggerCharacters:

on_attach = function(client, bufnr)
  client.server_capabilities.completionProvider.triggerCharacters = {'a', 'e', 'i', 'o', 'u'}
  require'lsp_compl'.attach(client, bufnr)
end

Can I trigger the completion manually?

Yes, call require'lsp_compl'.trigger_completion() while in insert mode. But this won't be much different from using the vim.lsp.omnifunc via i_CTRL-X_CTRL-O.

Can I re-trigger completion when I hit backspace or <C-w> while completion is active?

Yes, you have three options:

1. Manually trigger the completion (see previous question)
2. Enable trigger_on_delete:

  -- ...
  on_attach = function(client, bufnr)
    require'lsp_compl'.attach(client, bufnr, { trigger_on_delete = true })
  end
  -- ...

3. Define a key mapping that always re-triggers it:

inoremap <expr> <BS> (pumvisible() ? "\<BS><cmd> :lua require'lsp_compl'.trigger_completion()<CR>" : "\<BS>")