jobreadlines.vim

 " Append lines to a buffer. Use the Neovim API instead of the traditional
"
"   call append(line('$'), a:data)
"
" Reason: nvim_buf_set_lines allows adding lines to a buffer which is not
" the active one. This means we don't have to fiddle with the users' active
" buffers.
function s:appendlines(buf, list)
  if !empty(a:list)
    call nvim_buf_set_lines(a:buf, -1, -1, v:false, a:list)
  endif
endfunction

function cb.on_stdout(job_id, data, event) dict
  " If we have more than a single line, we can be sure there's some newline in
  " there, so flush stdoutbuf.
  if len(a:data) > 1
    " Technically, this could make us add an empty line to the buffer: if
    " self.stdoutbuf and a:data[0] are empty. I think this is intentional...
    "
    " But what happens if self.stdoutbuf was already '' (from a newline), and
    " we get a newline now in a:data? Wouldn't we be collapsing that newline?
    call s:appendlines(self.buf, [self.stdoutbuf . remove(a:data, 0)])
    let self.stdoutbuf = ''
  endif

  " Print all lines save for the last, which may be incomplete.
  call s:appendlines(self.buf, a:data[:-2])

  if !empty(a:data[-1])
    let self.stdoutbuf = a:data[-1]
  endif

  " I guess we just ignore empty last list items... (TODO)
endfunction

function cb.on_exit(job_id, data, event) dict
  if !empty(self.stdoutbuf)
    call s:appendlines(self.buf, [self.stdoutbuf])
  endif
  unlet self.stdoutbuf
endfunction