setlocal indentexpr=SligeIndent()

function! SligeIndent()
  let line = getline(v:lnum)
  let previousNum = prevnonblank(v:lnum - 1)
  let previous = getline(previousNum)

  if previous =~ "(" && previous !~ ")" && (line !~ ")" || line !~ "%)")
    return indent(previousNum) + &shiftwidth
  elseif (line =~ ")" || line =~ "%)") && line !~ "("
    return indent(previousNum) - &shiftwidth
  elif previous =~ "{" && previous !~ "}" && (line !~ "}" || line !~ "%}")
    return indent(previousNum) + &shiftwidth
  elseif (line =~ "}" || line =~ "%}") && line !~ "{"
    return indent(previousNum) - &shiftwidth
  elif previous =~ "[" && previous !~ "]" && (line !~ "]" || line !~ "%]")
    return indent(previousNum) + &shiftwidth
  elseif (line =~ "]" || line =~ "%]") && line !~ "["
    return indent(previousNum) - &shiftwidth
  else
    return indent(previousNum)
  endif
endfunction