gistfile1.txt

inoremap <buffer> <expr> ] CloseOrCompl()

function! CloseOrCompl()
  if pumvisible()
    return "\<C-n>"
  endif

  let a = GetCharsUntilHere()
  let tmp = 0
  let in_string = 'no'
  for i in reverse(range(0, len(a) - 1))
    if in_string != 'no'
      if a[i] == in_string
        let in_string = 'no'
      else
        " Ignore the contents of String literal
      endif
    elseif a[i] == '"'
      let in_string = '"'
    elseif a[i] == "'"
      let in_string = "'"
    elseif a[i] == ']'
      let tmp += 1
    elseif a[i] == '['
      if tmp <= 0
        return ']'
      else
        let tmp -= 1
      endif
    endif
  endfor
  return "\<C-n>"
endfunction

function! GetCharsUntilHere()
  let [_, lnum, col, _] = getpos('.')
  let a = getline(1, lnum - 1)
  call add(a, getline(lnum)[:col-1])
  return join(a, "\n")
endfunction