class Grape::Validations::AttributesIterator

def do_each(params_to_process, parent_indicies = [], &block)
  @scope.reset_index # gets updated depending on the size of params_to_process
  params_to_process.each_with_index do |resource_params, index|
    # when we get arrays of arrays it means that target element located inside array
    # we need this because we want to know parent arrays indicies
    if resource_params.is_a?(Array)
      do_each(resource_params, [index] + parent_indicies, &block)
      next
    end
    if @scope.type == Array
      next unless @original_params.is_a?(Array) # do not validate content of array if it isn't array
      # fill current and parent scopes with correct array indicies
      parent_scope = @scope.parent
      parent_indicies.each do |parent_index|
        parent_scope.index = parent_index
        parent_scope = parent_scope.parent
      end
      @scope.index = index
    end
    yield_attributes(resource_params, @attrs, &block)
  end
end

def each(&block)
  do_each(@params, &block) # because we need recursion for nested arrays
end

def initialize(validator, scope, params)
  @scope = scope
  @attrs = validator.attrs
  @original_params = scope.params(params)
  @params = Array.wrap(@original_params)
end

def skip?(val)
  val == Grape::DSL::Parameters::EmptyOptionalValue
end

def yield_attributes(_resource_params, _attrs)
  raise NotImplementedError
end