gistfile1.txt

s = "ab[cd]ef"
expected = ['a', 'b', ['c', 'd' ], 'e', 'f']




def parse(xs)
  result = []

  while not xs.empty?
    x = xs[0]
    xs.slice!(0, 1)
    if x == '['
      got = parse(xs)
      result.push(got)
    elsif x == ']'
      return result
    else
      result.push(x)
    end
  end
  return result
end


p parse("[][]")