Filter the quickfix list with fzf

quickfix-fzf.vim

function! s:format_qf_line(line)
  let parts = split(a:line, ':')
  return { 'filename': parts[0]
         \,'lnum': parts[1]
         \,'col': parts[2]
         \,'text': join(parts[3:], ':')
         \ }
endfunction

function! s:qf_to_fzf(key, line) abort
  let l:filepath = expand('#' . a:line.bufnr . ':p')
  return l:filepath . ':' . a:line.lnum . ':' . a:line.col . ':' . a:line.text
endfunction

function! s:fzf_to_qf(filtered_list) abort
  let list = map(a:filtered_list, 's:format_qf_line(v:val)')
  if len(list) > 0
    call setqflist(list)
    copen
  endif
endfunction

command! FzfQF call fzf#run({
      \ 'source': map(getqflist(), function('<sid>qf_to_fzf')),
      \ 'down':   '20',
      \ 'sink*':   function('<sid>fzf_to_qf'),
      \ 'options': '--reverse --multi --bind=ctrl-a:select-all,ctrl-d:deselect-all --prompt "quickfix> "',
      \ })