LazyPager

lazy_pager.rb

class LazyPager
  include Enumerable

  def initialize(&block)
    @page = 0
    @block = block
    @items = []
    @index = 0
  end

  def each(&block)
    loop do
      block.call(next_item)
    end
  end

  private

  attr_reader :page, :block, :items, :index

  def next_item
    if index >= items.length
      generate_next_page
      @index = 0
      return next_item
    end

    items[index].tap do
      @index += 1
    end
  end

  def generate_next_page
    @page += 1
    @items = block.call(page)
    raise StopIteration unless items.is_a?(Enumerable)
    raise StopIteration if items.empty?
  end
end