completion-nvim

completion-nvim is an auto completion framework that aims to provide a better completion experience with neovim's built-in LSP. Other LSP functionality is not supported.

Features

Asynchronous completion using the libuv api.
Automatically open hover windows when popupmenu is available.
Automatically open signature help if it's available.
Snippets integration with UltiSnips and Neosnippet and vim-vsnip.
Apply additionalTextEdits in LSP spec if it's available.
Chain completion support inspired by vim-mucomplete

Demo

Demo using sumneko_lua

Prerequisites

Neovim nightly
You should set up your language server of choice with the help of nvim-lspconfig

Install

Install with any plugin manager by using the path on GitHub.

Plug 'nvim-lua/completion-nvim'

Setup

completion-nvim requires several autocommands set up to work properly. You should set it up using the on_attach function like this.

lua require'nvim_lsp'.pyls.setup{on_attach=require'completion'.on_attach}

Change pyls to whichever language server you're using.
If you want completion-nvim to be set up for all buffers instead of only being used when lsp is enabled, call the on_attach function directly:

" Use completion-nvim in every buffer
autocmd BufEnter * lua require'completion'.on_attach()

NOTE It's okay to set up completion-nvim without lsp. It will simply use another completion source instead(Ex: snippets).

Supported Completion Source

built-in sources
- lsp: completion source for neovim's built-in LSP.
- snippet: completion source for snippet.
- path: completion source for path from current file.
ins-complete sources
- See :h ins-completion and wiki
external sources
- completion-buffers: completion for buffers word.
- completion-treesitter: treesitter based completion sources.
- vim-dadbod-completion: completion sources for vim-dadbod.
- completion-tabnine: AI code completion tool TabNine integration.
- completion-tags: Slightly improved ctags completion

Configuration

Recommended Setting

" Use <Tab> and <S-Tab> to navigate through popup menu
inoremap <expr> <Tab>   pumvisible() ? "\<C-n>" : "\<Tab>"
inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"

" Set completeopt to have a better completion experience
set completeopt=menuone,noinsert,noselect

" Avoid showing message extra message when using completion
set shortmess+=c

Enable/Disable auto popup

By default auto popup is enabled, turn it off by

let g:completion_enable_auto_popup = 0

Or you can toggle auto popup on the fly by using command CompletionToggle
You can manually trigger completion with mapping key by

"map <c-p> to manually trigger completion
imap <silent> <c-p> <Plug>(completion_trigger)

Or you want to use <Tab> as trigger keys

nmap <tab> <Plug>(completion_smart_tab)
nmap <s-tab> <Plug>(completion_smart_s_tab)

Enable Snippets Support

By default other snippets source support are disabled, turn them on by

" possible value: 'UltiSnips', 'Neosnippet', 'vim-vsnip', 'snippets.nvim'
let g:completion_enable_snippet = 'UltiSnips'

Supports UltiSnips, Neosnippet, vim-vsnip and snippets.nvim

LSP Based Snippet parsing

Some language server have snippet support but neovim couldn't handle that for now, completion-nvim can integrate with other LSP snippet parsing plugin for this support.
Right now only support vim-vsnip(require vim-vsnip-integ), it should work out of the box if you have vim-vsnip and vim-vsnip-integ installed.

Chain Completion Support

completion-nvim supports chain completion, which use other completion sources and ins-completion as a fallback for lsp completion.
See wiki for details on how to set this up.

Changing Completion Confirm key

By default <CR> is used to confirm completion and expand snippets, change it by

let g:completion_confirm_key = "\<C-y>"

Make sure to use " " and add escape key \ to avoid parsing issues.
If the confirm key has a fallback mapping, for example when using the auto pairs plugin, it maps to <CR>. You can avoid using the default confirm key option and use a mapping like this instead.

let g:completion_confirm_key = ""
imap <expr> <cr>  pumvisible() ? complete_info()["selected"] != "-1" ?
                 \ "\<Plug>(completion_confirm_completion)"  : "\<c-e>\<CR>" :  "\<CR>"

Enable/Disable auto hover

By default when navigating through completion items, LSP's hover is automatically called and displays in a floating window. Disable it by

let g:completion_enable_auto_hover = 0

Enable/Disable auto signature

By default signature help opens automatically whenever it's available. Disable it by

let g:completion_enable_auto_signature = 0

Sorting completion items

You can decide how your items being sorted in the popup menu. The default value is "alphabet", change it by

" possible value: "length", "alphabet", "none"
let g:completion_sorting = "length"

If you don't want any sorting, you can set this value to "none".

Matching Strategy

There are three different kind of matching technique implement in completion-nvim: substring, fuzzy, exact or all.
You can specify a list of matching strategy, completion-nvim will loop through the list and assign priority from high to low. For example

let g:completion_matching_strategy_list = ['exact', 'substring', 'fuzzy', 'all']

NOTE Fuzzy match highly dependent on what language server you're using. It might not work as you expect on some language server.

You can also enable ignore case matching by

g:completion_matching_ignore_case = 1

Trigger Characters

By default, completion-nvim respect the trigger character of your language server, if you want more trigger characters, add it by

let g:completion_trigger_character = ['.', '::']

NOTE use :lua print(vim.inspect(vim.lsp.buf_get_clients()[1].server_capabilities.completionProvider.triggerCharacters)) to see the trigger character of your language server.

If you want different trigger character for different languages, wrap it in an autocommand like

augroup CompletionTriggerCharacter
    autocmd!
    autocmd BufEnter * let g:completion_trigger_character = ['.']
    autocmd BufEnter *.c,*.cpp let g:completion_trigger_character = ['.', '::']
augroup end

Trigger keyword length

You can specify keyword length for triggering completion, if the current word is less then keyword length, completion won't be triggered.

let g:completion_trigger_keyword_length = 3 " default = 1

NOTE completion-nvim will ignore keyword length if you're on trigger character.

Trigger on delete

completion-nvim doesn't trigger completion on delete by default because sometimes I've found it annoying. However, you can enable it by

let g:completion_trigger_on_delete = 1

Timer Adjustment

completion-nvim uses a timer to control the rate of completion. You can adjust the timer rate by

let g:completion_timer_cycle = 200 "default value is 80

Per Server Setup

You can have different setup for each server in completion-nvim using lua, see [wiki] (https://github.com/nvim-lua/completion-nvim/wiki/per-server-setup-by-lua) for more guide.

Compatibility with diagnostic-nvim

This plugin only focuses on the completion part of the built-in LSP. If you want similar help with diagnostics (e.g. virtual text, jump to diagnostic, open line diagnostic automatically...), take a look at diagnostic-nvim.
Both diagnostic-nvim and completion-nvim require setting up via on_attach. To use them together, create a wrapper function like this.

lua << EOF
local on_attach_vim = function(client)
  require'completion'.on_attach(client)
  require'diagnostic'.on_attach(client)
end
require'nvim_lsp'.pyls.setup{on_attach=on_attach_vim}
EOF

Trouble Shooting

This plugin is in the early stages and might have unexpected issues. Please follow wiki for trouble shooting.
Feel free to post issues on any unexpected behavior or open a feature request!

7415963987456321/completion-nvim