You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: decode_string.rb
    path of file: ./repos/algorithms/src
    
    the code of the file until where you have to start completion: # @param {String} s
# @return {String}
def decode_string(s)
  strings = ['']
  dups = []
  str = ''
  i = 0
  while i < s.size do
    if (s[i].to_i > 0)
      j = i+1
      j += 1 while
    
def decode_string(s)
  strings = ['']
  dups = []
  str = ''
  i = 0
  while i < s.size do
    if (s[i].to_i > 0)
      j = i+1
      j += 1 while s[j] != '['
      num = s[i...j].to_i
      dups.push(num)
      strings.push(str)
      i = j+1
    elsif s[i] == ']'
      num = dups.pop
      str = strings.pop
      str *= num
      prev = strings.pop
      strings.push(prev + str)
      str = ''
      i+=1
    elsif s[i] != '['
      str = strings.pop || ''
      str += s[i]
      strings.push(str)
      str = ''
      i+=1
    end
  end