async omnifunc

autoload_asyncomni.vim

" save all the completions
let s:completions = []

function! asyncomni#omnifunc(findstart, base)
    if a:findstart
        let l:line_string = getline('.')
        let l:line = line('.')
        let l:col = col('.')
        " locate start of the word
        let l:start = l:col -1
        while l:start > 0 && l:line_string[l:start -1] =~ '\a'
            let l:start -= 1
        endwhile
        echom 'l:start'.l:start
        return l:start
    endif
    return s:completions
endfunction

let s:timer = -1
function! s:complete()
    if s:timer == -1
        let s:timer = timer_start(1000, function('s:loaded_completions'))
    endif
endfunction

function! s:loaded_completions(timer)
    let s:completions = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
    " since this is a callback we got s:complete asynchrounsly
    " refresh the list since this is async
    if !empty(s:completions)
        setlocal completeopt-=longest
        setlocal completeopt+=menuone
        setlocal completeopt-=menu
        if &completeopt !~# 'noinsert\|noselect'
          setlocal completeopt+=noselect
        endif
        call feedkeys("\<C-x>\<C-o>", 'n')
    endif
endfunction

augroup asyncomni_completor
    autocmd!
    autocmd TextChangedI * call s:complete()
augroup end

ftdetect_asyncomni.vim

if !exists('g:loaded_asyncomni')
    let g:loaded_asyncomni = 1
endif
let g:loaded_asyncomni = 1

if exists('&omnifunc')
    setl omnifunc+=asyncomni#omnifunc
endif

Credit goes to https://github.com/maralla/completor.vim (https://github.com/maralla/completor.vim/blob/master/LICENSE)

This is a really interesting approach! Thanks for sharing! Glad I found it years later 😛 going to see if I can get it working in https://github.com/Olical/conjure