Making functions react to keypress

Question

Im very new to vim scripting. I have the following script in my .vimrc:

• If there is no user input aka I press <CR> => go to recent buffer
• If input is 'd' => delete all buffers except for the current one
• Else go to inputted buffer.

"Fast buffer switch
function Warp()
  ls
  call inputsave()
  let bufname = input('warp: ')
  call inputrestore()
  if bufname == ""
    b#
  elseif bufname == "d"
    %bd|e#|bd#
  else
    exe "b " . bufname
  endif
endfunction
nnoremap <silent> <C-f> :call Warp()<CR>

The :bcommand works so that I dont have to write the full filepath but only a substring of the file name. For example I can navigate to bar/foo/helloworld.js with :b hello. However, sometimes file names can overlap which causes :b to error out. An intuitive solution to this is to use tab-completion to select the correct file when using :b on the command line. However, I dont know how this could be integrated into my function or even if it is possible. Somethings I noticed:

• nnoremap <C-f> :b allows me to use tab-completion
• getchar() == 13 allows me to detect <CR>
• Maybe something with feedkeys but I dont know if that works with cmdline. Some further ideas I have but dont think is possible in simple vim scripting is catching the error so that the user can revise or use tab-completion the file name inputted clashes.

Thank you in advance. Any advice is greatly appreciated.

Answer 1

A simple fix is to use the third argument of input, which is a {completion} type (list at :help :command-completion):

…
const bufname = input('warp: ', '', 'buffer')
…

(I used const instead of let, too.)

Answer 2

I ended up writing this little script:

" --Warp: fast buffer switch
function Warp(...)
  let bufname = a:1
  if bufname == ""
    b#
  else
    if bufname == "d"
      echo("d")
      %bd|e#|bd#
    else
      exe "b " . bufname
    endif
  endif
endfunction
command! -nargs=? -complete=buffer Warp :call Warp(<q-args>)
nnoremap <C-f> :buffers<CR>:Warp 

The UI isnt as nice as the first iteration because the command :buffers stays in the view and :Warp doesnt feel like im filling into input box like warp: but the tab-completion works perfectly. Many thanks to @statox for helping me out. Any advice for extending my script will be greatly appreciated.