spacevim/bundle/vim-matchup/test/forwhile.vim

  if a:findstart
    if exists('s:completer') | unlet s:completer | endif

    let l:pos  = col('.') - 1
    let l:line = getline('.')[:l:pos-1]
    for l:completer in s:completers
      if !get(l:completer, 'enabled', 1) | continue | endif

      for l:pattern in l:completer.patterns
        if l:line =~# l:pattern
          let s:completer = l:completer
          while l:pos > 0
            if l:line[l:pos - 1] =~# '{\|,\|\[\|\\'
                  \ || l:line[l:pos-2:l:pos-1] ==# ', '
              let s:completer.context = matchstr(l:line, '\S*$')
              return l:pos
            else
              let l:pos -= 1
            endif
          endwhile
          return -2
        endif
      endfor
    endfor
    return -3
  else
    if !exists('s:completer') | return [] | endif

    return g:matchup_complete_close_braces && get(s:completer, 'inside_braces', 1)
          \ ? s:close_braces(s:completer.complete(a:base))
          \ : s:completer.complete(a:base)
  endif