VIM: how to send entire line to a buffer of type “Terminal”?

Question

In Vim 8, you can open a terminal inside Vim with the term command. This opens a new buffer of type terminal inside vim. Is there any way of sending lines from other buffers to this type of buffer?

For example:

nmap <some binding> <sends the entire line under cursor to buffer of type='terminal'>

What I am trying to achieve with this is to evaluate REPL statements without using any plugins

Thanks for any help in advance!

Answer 1

An awkward solution
Copy content into a register from an editing window and paste in to the :terminal window with <CTRL-W> " {reg} to run it.

Example with one editing buffer and one :terminal buffer running bash:

• text content in editing window
  echo hello

• cmd to copy the content to the 0 register
  :vipy

• move to the terminal window
  <CTRL-W> W

• paste 0 register into terminal window
  <CTRL-W> "0

• :terminal output
  hello

• move back to editing window
  <CTRL-W> W

... continue editing...

This also works for python REPL and probably for other language's REPL.

Here is a simpler alternative
Using term_sendkeys :

• open a vim terminal and start the REPL
  check which buffer the terminal is in with :ls
  this example assumes the terminal is in buffer 2

• cmd to copy the content to the " register (the unamed register) and paste/run in the terminal
  :%y | call term_sendkeys(2, @")

The command can then be mapped like this example:
nnoremap <leader>sk :%y \| :call term_sendkeys(2, @")<CR>

There is also at least two plugins available.
(I haven't tried them):
https://vimawesome.com/plugin/vim-sendtowindow
and
https://github.com/habamax/vim-sendtoterm

Answer 2

As Luc Hermitte pointed out, you can use :h term_sendkeys to send commands to terminal buffer, the hard part is to manage the terminal buffer:

function s:exec_on_term(lnum1, lnum2)
  " get terminal buffer
  let g:terminal_buffer = get(g:, 'terminal_buffer', -1)
  " open new terminal if it doesn't exist
  if g:terminal_buffer == -1 || !bufexists(g:terminal_buffer)
    terminal
    let g:terminal_buffer = bufnr('')
    wincmd p
  " split a new window if terminal buffer hidden
  elseif bufwinnr(g:terminal_buffer) == -1
    exec 'sbuffer ' . g:terminal_buffer
    wincmd p
  endif
  " join lines with "\<cr>", note the extra "\<cr>" for last line
  " send joined lines to terminal.
  call term_sendkeys(g:terminal_buffer,
        \ join(getline(a:lnum1, a:lnum2), "\<cr>") . "\<cr>")
endfunction

command! -range ExecOnTerm call s:exec_on_term(<line1>, <line2>)
nnoremap <leader>ex :ExecOnTerm<cr>
vnoremap <leader>ex :ExecOnTerm<cr>

read comment as explanation

usage

execute single line in normal mode, multiple lines in visual mode.