normalize_params (lib/rack/utils.rb)

# File lib/rack/utils.rb, line 129
    def normalize_params(params, name, v = nil)
      name =~ %r(\A[\[\]]*([^\[\]]+)\]*)
      k = $1 || ''
      after = $' || ''

      return if k.empty?

      if after == ""
        params[k] = v
      elsif after == "["
        params[name] = v
      elsif after == "[]"
        params[k] ||= []
        raise ParameterTypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        params[k] << v
      elsif after =~ %r(^\[\]\[([^\[\]]+)\]$) || after =~ %r(^\[\](.+)$)
        child_key = $1
        params[k] ||= []
        raise ParameterTypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        if params_hash_type?(params[k].last) && !params[k].last.key?(child_key)
          normalize_params(params[k].last, child_key, v)
        else
          params[k] << normalize_params(params.class.new, child_key, v)
        end
      else
        params[k] ||= params.class.new
        raise ParameterTypeError, "expected Hash (got #{params[k].class.name}) for param `#{k}'" unless params_hash_type?(params[k])
        params[k] = normalize_params(params[k], after, v)
      end

      return params
    end