Is there a way to preview the line where the corresponding open bracket is for a close bracket?

Question

If I am using IntelliJ and I hover over a close bracket for a scope that starts somewhere that is not currently visible, it shows a popup at the top of the window previewing the line where with the corresponding open bracket.

Is there some way to do this in Vim? I tried searching but I don't know what this is called so it is hard to find any useful results. I think it should be possible using balloons, but even if there is a way that just shows a preview as the top visible line of the buffer that would be great.

Answer 1

Yes- the plugin match-up has this feature: https://github.com/andymass/vim-matchup

Using the option

let g:matchup_matchparen_offscreen = { 'method': 'popup' }

There is also the ability to show the match in the statusline (the default):

let g:matchup_matchparen_offscreen = { 'method': 'status' }`

Answer 2

I guess you should use Mass's plugin in his answer.

If you want to know how to do it, you can check this answer.

---

This is a small task, you can do it with :h popup window

The result looks like this:

|  1 hello bracket {
| 12
| 13
| 14
| 15
| 16
| 17
| 18
| 19
| 20 }

Read comment as explanation:

" show open pair on left top of current window if cursor on (, [ or {.
" close popup window if cursor moved in normal, visual, insert mode.
augroup pair_popup_group | au!
  autocmd CursorHold * call s:popup_open_pair()
augroup end

let s:pair_popup_winid = 0

function s:popup_open_pair() abort

  " check if already popped up
  if s:pair_popup_winid != 0
    return
  endif

  " check if current character is close pair character
  let c = matchstr( getline('.'), printf('\%%%dc.', col('.') ) )
  if stridx(')]}', c) == -1
    return
  endif

  " check if open pair in current window.
  " get matching pair line, add space padded line number to it.
  try
    let win_top_buf_lnum = line('.') - winline() + 1
    let cview = winsaveview()
    keepjumps norm! %
    if line('.') >= win_top_buf_lnum
      return
    endif

    let content = printf( ' %*d %s', len( line('$') ), line('.'), getline('.') )
  finally
    call winrestview(cview)
  endtry

  " show matching pair line on first screen line of current window
  let wpos = win_screenpos( winnr() )
  let s:pair_popup_winid = popup_create(
        \ content, { 'line' : wpos[0], 'col' : wpos[1] })

  " close popup if cursor moved
  autocmd pair_popup_group CursorMoved,CursorMovedI * ++once
        \  call popup_close(s:pair_popup_winid)
        \| let s:pair_popup_winid = 0

endfunction

Answer 3

You could probably mess around with the new popup features.

Or you might be able to do something with :ptag.

But your best bet is to learn the mighty % key.

To quote :help %:

%           Find the next item in this line after or under the
            cursor and jump to its match. |inclusive| motion.
            Items can be:
            ([{}])      parenthesis or (curly/square) brackets
                    (this can be changed with the
                    'matchpairs' option)
            /* */       start or end of C-style comment
            #if, #ifdef, #else, #elif, #endif
                    C preprocessor conditionals (when the
                    cursor is on the # or no ([{
                    following)
            For other items the matchit plugin can be used, see
            |matchit-install|.  This plugin also helps to skip
            matches in comments.

What this means is that for almost any construct that has a concept of "matching," you can hit % to jump to the next "match."

In the case of your switch example, from

switch (var) {
  // lots of code...
} // <- cursor

Hitting % takes you to the switch line, and % takes you back. Easy-peasy.