custom completion source

Create custom completion source

You can create your own completion source and integrate it into the autocomplete items easily. Let's use a completion source that autocomplete month for example.

• Create a lua file in your &rtp path(for example: ~/.config/nvim/lua). Let's call it month.lua.
• Put this code in month.lua

local M = {}

function M.getCompletionItems(prefix, score_func)
  local complete_items = {}
  -- define your total completion items
  local items = {'January', 'Feburary', 'March', 'April', 'May', 'June',
                'July', 'August', 'September', 'October', 'Novermber', 
                'December'}
  -- find matches items and put them into complete_items
  for _, month in ipairs(items) do
    -- score_func is a fuzzy match scoring function
    local score = score_func(prefix, month)
    if score < #prefix/2 then
      -- if you're not familiar with complete_items, see `:h complete-items`
      table.insert(complete_items, {
          word = month,
          kind = 'month',
          score = score,
          icase = 1,
          dup = 1,
          empty = 1,
        })
    end
  end
  return complete_items
end

M.complete_item = {
  item = M.getCompletionItems
}

return M

• You can register this completion source by putting a single line to your init.vim

" addCompleteItems is defined in source.lua,
" the first argument refer to the chain completion list's index,
" the second argument is the function that get your complete items
lua require'source'.addCompleteItems('month', require'month'.complete_item)

• You have successfully create your own completion source! Just put it in your chain completion list and you can use it. For example put this in your init.vim:

let g:completion_chain_complete_list = [
    \{'ins_complete': v:false, 'complete_items': ['lsp', 'snippet', 'month']},
    \{'ins_complete': v:true,  'mode': '<c-p>'},
\]|

• Enjoy your new completion source!