parsing string formatted as rails-style nested params Hash

parse_www_encoded_form.rb

def parse_www_encoded_form(www_encoded_form)
  URI.decode_www_form(www_encoded_form).each do |pair|
    # returns array of names between '[' and ']' characters
    key_parts = pair.first.split(/\]\[|\[|\]/)

    current_hash = @params
    new_key = key_parts.shift

    # this does not run unless key_parts.count > 1
    until key_parts.empty? do
      # point current hash to hash at current_hash[new_key]. If
      # current_hash[new_key] is nil, set it (and current_hash) to {}
      current_hash = current_hash[new_key] ||= {}

      # grab the next key_part
      new_key = key_parts.shift
    end

    # the final key is paired in the deepest-nested hash 
    # with the actual value
    current_hash[new_key] = pair.last
  end
end