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Completion with sources

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Qiming zhao edited this page Oct 22, 2022 · 60 revisions

Highlights of coc.nvim's completion

  • Full LSP completion support, especially snippet and additionalTextEdit feature.
  • Completion resolving on completion item change, asynchronous completion resolve on completion item change and the detail and documentation will be shown in a float window when possible.
  • Asynchronous and parallel completion request. Unless using vim sources, your vim will never be blocked.
  • Incomplete request and cancel request support, only incomplete completion requests will be triggered on filtering completion items and cancellation requests are sent to servers only when necessary.
  • Real-time buffer keywords, generate buffer keywords on buffer change with only changed lines. Plus, Locality bonus feature from VSCode is enabled by default.
  • Filter completion items when possible. When you do a fuzzy filter with completion items, coc.nvim will filter the items when possible, which makes it much faster.

Trigger mode of completion

There are 3 different trigger modes:

  • always, the default mode, which triggers completion on a letter inserted or triggerCharacters (or trigger pattern match) defined by the current activated sources.
  • trigger, only trigger completion when you type triggerCharacters (or trigger pattern match) defined by the completion sources.
  • none, disable auto trigger completion, you will have to trigger the completion manually.

Lots of completion behavior can be changed by using the configuration file, check out :h coc-config-suggest for details.

Limitation of coc.nvim's completion

There's no function of coc.nvim that can be used as omnifunc because it's not possible to support all LSP completion features when using omnifunc.

For features like textEdit and additionalTextEdits(mostly used by automatic import feature) of LSP to work, you have to confirm completion by coc#pum#confirm()

Indent by indent keys is blocked during completion to avoid unexpected indent when selecting completion item, to trigger indent, use coc#pum#confirm() or coc#pum#insert() to finish completion.

Use <cr> to confirm completion

You have to remap <cr> to make it confirms completion.

inoremap <expr> <cr> coc#pum#visible() ? coc#pum#confirm() : "\<CR>"

To make <cr> select the first completion item and confirm the completion when no item has been selected:

inoremap <silent><expr> <cr> coc#pum#visible() ? coc#_select_confirm() : "\<C-g>u\<CR>"

Note: \<C-g>u is used to break undo level.

To make coc.nvim format your code on <cr>:

inoremap <silent><expr> <cr> coc#pum#visible() ? coc#_select_confirm() : "\<C-g>u\<CR>\<c-r>=coc#on_enter()\<CR>"

Use coc#pum#info() if you need to confirm completion, only when there's selected complete item:

inoremap <silent><expr> <cr> coc#pum#visible() && coc#pum#info()['index'] != -1 ? coc#pum#confirm() : "\<C-g>u\<CR>"

Use <Tab> or custom key for trigger completion

You can make use of coc#refresh() to trigger completion like this:

" use <tab> for trigger completion and navigate to the next complete item
function! CheckBackspace() abort
  let col = col('.') - 1
  return !col || getline('.')[col - 1]  =~# '\s'
endfunction

inoremap <silent><expr> <Tab>
      \ coc#pum#visible() ? coc#pum#next(1) :
      \ CheckBackspace() ? "\<Tab>" :
      \ coc#refresh()

Note: the <tab> could be remapped by another plugin, use :verbose imap <tab> to check if it's mapped as expected.

" use <c-space>for trigger completion
inoremap <silent><expr> <c-space> coc#refresh()
" Use <C-@> on vim
inoremap <silent><expr> <c-@> coc#refresh()

Use <Tab> and <S-Tab> to navigate the completion list:

inoremap <expr> <Tab> coc#pum#visible() ? coc#pum#next(1) : "\<Tab>"
inoremap <expr> <S-Tab> coc#pum#visible() ? coc#pum#prev(1) : "\<S-Tab>"

Completion sources

Use command :CocList sources to get current completion source list.

Bundled sources.

Name Shortcut Description
around [A] Words of the current buffer.
buffer [B] Words of other open buffers.
file [F] Filename completion, auto-detected.

Configuring sources

You can configure completion sources by using coc-settings.json

  • "coc.source.{name}.enable": controls if the source is enabled.
  • "coc.source.{name}.shortcut": shortcut used in completion menu.
  • "coc.source.{name}.priority": priority of the source, lower priority sources will be sorted after high priority sources when they have same score.
  • "coc.source.{name}.disableSyntaxes": syntax names used to disable source from completion, eg: ["comment", "string"]
  • "coc.source.around.firstMatch": Filter complete items by first letter strict match, default true.
  • "coc.source.buffer.firstMatch": Filter complete items by first letter strict match, default true.
  • "coc.source.buffer.ignoreGitignore": Ignore git ignored files for buffer words, default true.
  • "coc.source.file.trimSameExts": Filename extensions to trim extension names on file completion, default [".ts", ".js"]
  • "coc.source.file.ignoreHidden": Ignore completion for hidden files, default true.
  • coc.source.file.ignorePatterns: Ignore patterns of matcher module, default [].

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