module ActiveFedora::Aggregation
  ##
  # Lazily iterates over a doubly linked list, fixing up nodes if necessary.
  class OrderedReader
    include Enumerable
    attr_reader :root
    def initialize(root)
      @root = root
    end

    def each
      proxy = first_head
      while proxy
        yield proxy unless proxy.nil?
        next_proxy = proxy.next
        if next_proxy && next_proxy.prev != proxy
          next_proxy.try(:prev=, proxy)
        end
        proxy = next_proxy
      end
    end

    private

    def first_head
      root.head
    end
  end
end