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NCM2, formerly known as nvim-completion-manager, is a slim, fast and hackable completion framework for neovim.

Main features:

  1. Fast and asynchronous completion support, with vimscript friendly API.
  2. Smart on files with different languages, for example, css/javascript completion in html style/script tag.
  3. Function parameter expansion support using ncm2-snippet plugins.
  4. Language server protocol plugin integration.

Read our wiki page for a list of extensions and programming languages support for NCM2.

peek 2018-07-17 18-15

View demo vimrc at #19


  • :echo has("nvim-0.2.2") prints 1. Older versions has not been tested
  • :echo has("python3") prints 1. This is usually set by python3 -m pip install pynvim in shell and let g:python3_host_prog=/path/to/python/executable/ in vimrc.
  • Plugin nvim-yarp

For vim8 user, read the nvim-yarp README. Note that vim8 support is simply a bonus. It's not the goal of NCM2.


    " assuming you're using vim-plug:
    Plug 'ncm2/ncm2'
    Plug 'roxma/nvim-yarp'

    " enable ncm2 for all buffers
    autocmd BufEnter * call ncm2#enable_for_buffer()

    " IMPORTANT: :help Ncm2PopupOpen for more information
    set completeopt=noinsert,menuone,noselect

    " NOTE: you need to install completion sources to get completions. Check
    " our wiki page for a list of sources:
    Plug 'ncm2/ncm2-bufword'
    Plug 'ncm2/ncm2-path'

Optional Vimrc Tips

    " suppress the annoying 'match x of y', 'The only match' and 'Pattern not
    " found' messages
    set shortmess+=c

    " CTRL-C doesn't trigger the InsertLeave autocmd . map to <ESC> instead.
    inoremap <c-c> <ESC>

    " When the <Enter> key is pressed while the popup menu is visible, it only
    " hides the menu. Use this mapping to close the menu and also start a new
    " line.
    inoremap <expr> <CR> (pumvisible() ? "\<c-y>\<cr>" : "\<CR>")

    " Use <TAB> to select the popup menu:
    inoremap <expr> <Tab> pumvisible() ? "\<C-n>" : "\<Tab>"
    inoremap <expr> <S-Tab> pumvisible() ? "\<C-p>" : "\<S-Tab>"

    " wrap existing omnifunc
    " Note that omnifunc does not run in background and may probably block the
    " editor. If you don't want to be blocked by omnifunc too often, you could
    " add 180ms delay before the omni wrapper:
    "  'on_complete': ['ncm2#on_complete#delay', 180,
    "               \ 'ncm2#on_complete#omni', 'csscomplete#CompleteCSS'],
    au User Ncm2Plugin call ncm2#register_source({
            \ 'name' : 'css',
            \ 'priority': 9,
            \ 'subscope_enable': 1,
            \ 'scope': ['css','scss'],
            \ 'mark': 'css',
            \ 'word_pattern': '[\w\-]+',
            \ 'complete_pattern': ':\s*',
            \ 'on_complete': ['ncm2#on_complete#omni', 'csscomplete#CompleteCSS'],
            \ })

How Do I write Ncm2 Source?

One important step is to understand how and when completion gets triggered. Read :help ncm2#register_source carefully, or :help ncm2#register_source-example for quick start.

In case you don't know what tool you should use for async support. Here are some options available:


Refer to the debugging section of nvim-yarp

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