A completion engine plugin for neovim written in Lua. Completion sources are installed from external repositories and "sourced".

1. nvim-cmp's breaking changes are documented here.
2. This is my hobby project. You can support me via GitHub sponsors.
3. Bug reports are welcome, but I might not fix if you don't provide a minimal reproduction configuration and steps.

• No flicker
• Works properly
• Fully customizable via Lua functions
• Fully supports LSP's completion capabilities
  • Snippets
  • CommitCharacters
  • TriggerCharacters
  • TextEdit and InsertReplaceTextEdit
  • AdditionalTextEdits
  • Markdown documentation
  • Execute commands (Some LSP server needs it to auto-importing. e.g. sumneko_lua or purescript-language-server)
  • Preselect
  • CompletionItemTags
• Support pairs-wise plugin automatically

This example configuration uses vim-plug as the plugin manager.

call plug#begin(s:plug_dir)
Plug 'neovim/nvim-lspconfig'
Plug 'hrsh7th/cmp-nvim-lsp'
Plug 'hrsh7th/cmp-buffer'
Plug 'hrsh7th/cmp-path'
Plug 'hrsh7th/cmp-cmdline'
Plug 'hrsh7th/nvim-cmp'

" For vsnip users.
Plug 'hrsh7th/cmp-vsnip'
Plug 'hrsh7th/vim-vsnip'

" For luasnip users.
" Plug 'L3MON4D3/LuaSnip'
" Plug 'saadparwaiz1/cmp_luasnip'

" For ultisnips users.
" Plug 'SirVer/ultisnips'
" Plug 'quangnguyen30192/cmp-nvim-ultisnips'

" For snippy users.
" Plug 'dcampos/nvim-snippy'
" Plug 'dcampos/cmp-snippy'

call plug#end()

set completeopt=menu,menuone,noselect

lua <<EOF
  -- Setup nvim-cmp.
  local cmp = require'cmp'

  cmp.setup({
    snippet = {
      -- REQUIRED - you must specify a snippet engine
      expand = function(args)
        vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
        -- require('luasnip').lsp_expand(args.body) -- For `luasnip` users.
        -- vim.fn["UltiSnips#Anon"](args.body) -- For `ultisnips` users.
        -- require'snippy'.expand_snippet(args.body) -- For `snippy` users.
      end,
    },
    mapping = {
      ['<C-d>'] = cmp.mapping(cmp.mapping.scroll_docs(-4), { 'i', 'c' }),
      ['<C-f>'] = cmp.mapping(cmp.mapping.scroll_docs(4), { 'i', 'c' }),
      ['<C-Space>'] = cmp.mapping(cmp.mapping.complete(), { 'i', 'c' }),
      ['<C-y>'] = cmp.config.disable, -- Specify `cmp.config.disable` if you want to remove the default `<C-y>` mapping.
      ['<C-e>'] = cmp.mapping({
        i = cmp.mapping.abort(),
        c = cmp.mapping.close(),
      }),
      ['<CR>'] = cmp.mapping.confirm({ select = true }),
    },
    sources = cmp.config.sources({
      { name = 'nvim_lsp' },
      { name = 'vsnip' }, -- For vsnip users.
      -- { name = 'luasnip' }, -- For luasnip users.
      -- { name = 'ultisnips' }, -- For ultisnips users.
      -- { name = 'snippy' }, -- For snippy users.
    }, {
      { name = 'buffer' },
    })
  })

  -- Use buffer source for `/` (if you enabled `native_menu`, this won't work anymore).
  cmp.setup.cmdline('/', {
    sources = {
      { name = 'buffer' }
    }
  })

  -- Use cmdline & path source for ':' (if you enabled `native_menu`, this won't work anymore).
  cmp.setup.cmdline(':', {
    sources = cmp.config.sources({
      { name = 'path' }
    }, {
      { name = 'cmdline' }
    })
  })

  -- Setup lspconfig.
  local capabilities = require('cmp_nvim_lsp').update_capabilities(vim.lsp.protocol.make_client_capabilities())
  -- Replace <YOUR_LSP_SERVER> with each lsp server you've enabled.
  require('lspconfig')['<YOUR_LSP_SERVER>'].setup {
    capabilities = capabilities
  }
EOF

You can search for various completion sources here.

You can specify the following configuration options via cmp.setup { ... }.

The configuration options will be merged with the default config.

If you want to remove a default option, set it to false.

Defines the action of each key mapping. The following lists all the built-in actions:

• cmp.mapping.select_prev_item({ cmp.SelectBehavior.{Insert,Select} })
• cmp.mapping.select_next_item({ cmp.SelectBehavior.{Insert,Select} })
• cmp.mapping.scroll_docs(number)
• cmp.mapping.complete()
• cmp.mapping.close()
• cmp.mapping.abort()
• cmp.mapping.confirm({ select = bool, behavior = cmp.ConfirmBehavior.{Insert,Replace} }): If select is true and you haven't select any item, automatically selects the first item.

You can configure nvim-cmp to use these cmp.mapping like this:

mapping = {
  ['<C-n>'] = cmp.mapping.select_next_item({ behavior = cmp.SelectBehavior.Insert }),
  ['<C-p>'] = cmp.mapping.select_prev_item({ behavior = cmp.SelectBehavior.Insert }),
  ['<Down>'] = cmp.mapping.select_next_item({ behavior = cmp.SelectBehavior.Select }),
  ['<Up>'] = cmp.mapping.select_prev_item({ behavior = cmp.SelectBehavior.Select }),
  ['<C-d>'] = cmp.mapping.scroll_docs(-4),
  ['<C-f>'] = cmp.mapping.scroll_docs(4),
  ['<C-Space>'] = cmp.mapping.complete(),
  ['<C-e>'] = cmp.mapping.close(),
  ['<CR>'] = cmp.mapping.confirm({
    behavior = cmp.ConfirmBehavior.Replace,
    select = true,
  })
}

In addition, the mapping mode can be specified with the help of cmp.mapping(...). The default is the insert mode (i) if not specified.

mapping = {
  ...
  ['<Tab>'] = cmp.mapping(cmp.mapping.select_next_item(), { 'i', 's' })
  ...
}

The mapping mode can also be specified using a table. This is particularly useful to set different actions for each mode.

mapping = {
  ['<CR>'] = cmp.mapping({
    i = cmp.mapping.confirm({ select = true }),
    c = cmp.mapping.confirm({ select = false }),
  })
}

You can also provide a custom function as the action.

mapping = {
  ['<Tab>'] = function(fallback)
    if ...some_condition... then
      vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes('...', true, true, true), 'n', true)
    else
      fallback() -- The fallback function is treated as original mapped key. In this case, it might be `<Tab>`.
    end
  end,
}

A boolean value, or a function returning a boolean, that specifies whether to enable nvim-cmp's features or not.

Default:

function()
  return vim.api.nvim_buf_get_option(0, 'buftype') ~= 'prompt'
end

Lists all the global completion sources that will be enabled in all buffers. The order of the list defines the priority of each source. See the sorting.priority_weight option below.

It is possible to set up different sources for different filetypes using FileType autocommand and cmp.setup.buffer to override the global configuration.

" Setup buffer configuration (nvim-lua source only enables in Lua filetype).
autocmd FileType lua lua require'cmp'.setup.buffer {
\   sources = {
\     { name = 'nvim_lua' },
\     { name = 'buffer' },
\   },
\ }

Note that the source name isn't necessarily the source repository name. Source names are defined in the source repository README files. For example, look at the hrsh7th/cmp-buffer source README which defines the source name as buffer.

The source name.

The source customization options. It is defined by each source.

The priority of the source. If you don't specify it, the source priority will be determined by the default algorithm (see sorting.priority_weight).

The source specific keyword_pattern for override.

The source specific keyword_length for override.

The source specific maximum item count.

The source group index.

You can call built-in utility like cmp.config.sources({ { name = 'a' } }, { { name = 'b' } }).

Specify preselect mode. The following modes are available.

• cmp.PreselectMode.Item
  • If the item has preselect = true, nvim-cmp will preselect it.
• cmp.PreselectMode.None
  • Disable preselect feature.

Default: cmp.PreselectMode.Item

Which events should trigger autocompletion.

If you set this to false, nvim-cmp will not perform completion automatically. You can still use manual completion though (like omni-completion via the cmp.mapping.complete function).

Default: { types.cmp.TriggerEvent.TextChanged }

The default keyword pattern. This value will be used if a source does not set a source specific pattern.

Default: [[\%(-\?\d\+\%(\.\d\+\)\?\|\h\w*\%(-\w*\)*\)]]

The minimum length of a word to complete on; e.g., do not try to complete when the length of the word to the left of the cursor is less than keyword_length.

Default: 1

The function to resolve trigger_characters.

Default: function(trigger_characters) return trigger_characters end

vim's completeopt setting. Warning: Be careful when changing this value.

Default: menu,menuone,noselect

A default cmp.ConfirmBehavior value when to use confirmed by commitCharacters

Default: cmp.ConfirmBehavior.Insert

The function to resolve commit_characters.

The score multiplier of source when calculating the items' priorities. Specifically, each item's original priority (given by its corresponding source) will be increased by #sources - (source_index - 1) multiplied by priority_weight. That is, the final priority is calculated by the following formula:

final_score = orig_score + ((#sources - (source_index - 1)) * sorting.priority_weight)

Default: 2

When sorting completion items, the sort logic tries each function in sorting.comparators consecutively when comparing two items. The first function to return something other than nil takes precedence.

Each function must return boolean|nil.

You can use the preset functions from cmp.config.compare.*.

Default:

{
  cmp.config.compare.offset,
  cmp.config.compare.exact,
  cmp.config.compare.score,
  cmp.config.compare.recently_used,
  cmp.config.compare.kind,
  cmp.config.compare.sort_text,
  cmp.config.compare.length,
  cmp.config.compare.order,
}

If set to false, the documentation of each item will not be shown. Else, a table representing documentation configuration should be provided. The following are the possible options:

Border characters used for documentation window.

A neovim's winhighlight option for documentation window.

The documentation window's max width.

The documentation window's max height.

The documentation window's zindex.

The order of item's fields for completion menu.

A function to customize completion menu. The return value is defined by vim. See :help complete-items.

You can display the fancy icons to completion-menu with lspkind-nvim.

Please see FAQ if you would like to show symbol-text (e.g. function) and source (e.g. LSP) like compe.

local lspkind = require('lspkind')
cmp.setup {
  formatting = {
    format = lspkind.cmp_format(),
  },
}

See the wiki for more info on customizing menu appearance.

Use vim's native completion menu instead of custom floating menu.

Default: false

Specify whether to display ghost text.

Default: false

Show the source statuses

Invoke after nvim-cmp setup.

The abbr field.

The deprecated item's abbr field.

The matched characters highlight.

The fuzzy matched characters highlight.

The kind field.

The menu field.

You can use the following APIs.

Subscribes to the following events.

• confirm_done

Returns the current configuration.

Returns the completion menu is visible or not.

NOTE: This method returns true if the native popup menu is visible, for the convenience of defining mappings.

Returns the selected entry.

Returns the active entry.

NOTE: The preselected entry does not returned from this method.

Confirms the current selected item, if possible. If select is true and no item has been selected, selects the first item.

Invokes manual completion.

Closes the current completion menu.

Closes the current completion menu and restore the current line (similar to native <C-e> behavior).

Selects the next completion item if possible.

Selects the previous completion item if possible.

Scrolls the documentation window by delta lines, if possible.

Check the output of command :CmpStatus. It is likely that you specify the source name incorrectly.

NOTE: nvim_lsp will be sourced on InsertEnter event. It will show as unknown source, but this isn't a problem.

Some pair-wise plugin set up the mapping automatically. For example, vim-endwise will map <CR> even if you don't do any mapping instructions for the plugin.

But I think the user want to override <CR> mapping only when the mapping item is selected.

The nvim-cmp does it automatically.

The following configuration will be working as

1. If the completion-item is selected, will be working as cmp.mapping.confirm.
2. If the completion-item isn't selected, will be working as vim-endwise feature.

mapping = {
  ['<CR>'] = cmp.mapping.confirm()
}

You can use the following configuration.

cmp.setup {
  completion = {
    completeopt = 'menu,menuone,noinsert',
  }
}

At the moment, nvim-cmp requires a snippet engine to function correctly. You need to specify one in snippet.

snippet = {
  -- REQUIRED - you must specify a snippet engine
  expand = function(args)
    vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
    -- require('luasnip').lsp_expand(args.body) -- For `luasnip` users.
    -- vim.fn["UltiSnips#Anon"](args.body) -- For `ultisnips` users.
    -- require'snippy'.expand_snippet(args.body) -- For `snippy` users.
  end,
}

You can use nvim-cmp without auto-completion like this.

cmp.setup {
  completion = {
    autocomplete = false
  }
}

You can specify enabled = false like this.

autocmd FileType TelescopePrompt lua require('cmp').setup.buffer { enabled = false }

I've optimized nvim-cmp as much as possible, but there are currently some known / unfixable issues.

cmp-buffer source and too large buffer

The cmp-buffer source makes an index of the current buffer so if the current buffer is too large, it will slowdown the main UI thread.

vim.lsp.set_log_level

This setting will cause the filesystem operation for each LSP payload. This will greatly slow down nvim-cmp (and other LSP related features).

formatting = {
  format = require("lspkind").cmp_format({with_text = true, menu = ({
      buffer = "[Buffer]",
      nvim_lsp = "[LSP]",
      luasnip = "[LuaSnip]",
      nvim_lua = "[Lua]",
      latex_symbols = "[Latex]",
    })}),
},

You can find all the mapping examples in Example mappings.

Warning: If the LSP spec is changed, nvim-cmp will keep up to it without an announcement.

If you publish nvim-cmp source to GitHub, please add nvim-cmp topic for the repo.

You should read cmp types and LSP spec to create sources.

• The complete function is required. Others can be omitted.
• The callback argument must always be called.
• The custom source should only use require('cmp').
• The custom source can specify word property to CompletionItem. (It isn't an LSP specification but supported as a special case.)

Here is an example of a custom source.

local source = {}

---Source constructor.
source.new = function()
  local self = setmetatable({}, { __index = source })
  self.your_awesome_variable = 1
  return self
end

---Return the source is available or not.
---@return boolean
function source:is_available()
  return true
end

---Return the source name for some information.
function source:get_debug_name()
  return 'example'
end

---Return keyword pattern which will be used...
---  1. Trigger keyword completion
---  2. Detect menu start offset
---  3. Reset completion state
---@param params cmp.SourceBaseApiParams
---@return string
function source:get_keyword_pattern(params)
  return '???'
end

---Return trigger characters.
---@param params cmp.SourceBaseApiParams
---@return string[]
function source:get_trigger_characters(params)
  return { ??? }
end

---Invoke completion (required).
---  If you want to abort completion, just call the callback without arguments.
---@param params cmp.SourceCompletionApiParams
---@param callback fun(response: lsp.CompletionResponse|nil)
function source:complete(params, callback)
  callback({
    { label = 'January' },
    { label = 'February' },
    { label = 'March' },
    { label = 'April' },
    { label = 'May' },
    { label = 'June' },
    { label = 'July' },
    { label = 'August' },
    { label = 'September' },
    { label = 'October' },
    { label = 'November' },
    { label = 'December' },
  })
end

---Resolve completion item that will be called when the item selected or before the item confirmation.
---@param completion_item lsp.CompletionItem
---@param callback fun(completion_item: lsp.CompletionItem|nil)
function source:resolve(completion_item, callback)
  callback(completion_item)
end

---Execute command that will be called when after the item confirmation.
---@param completion_item lsp.CompletionItem
---@param callback fun(completion_item: lsp.CompletionItem|nil)
function source:execute(completion_item, callback)
  callback(completion_item)
end

require('cmp').register_source(source.new())

You can also create a source by Vim script like this (This is useful to support callback style plugins).

• If you want to return boolean, you must return v:true/v:false instead of 0/1.

let s:source = {}

function! s:source.new() abort
  return extend(deepcopy(s:source))
endfunction

" The other APIs are also available.

function! s:source.complete(params, callback) abort
  call a:callback({
  \   { 'label': 'January' },
  \   { 'label': 'February' },
  \   { 'label': 'March' },
  \   { 'label': 'April' },
  \   { 'label': 'May' },
  \   { 'label': 'June' },
  \   { 'label': 'July' },
  \   { 'label': 'August' },
  \   { 'label': 'September' },
  \   { 'label': 'October' },
  \   { 'label': 'November' },
  \   { 'label': 'December' },
  \ })
endfunction

call cmp#register_source('month', s:source.new())