Parse Error

lib/list.rb

require 'lib/node'



class List < Array



  def initialize

    @node_lists = []

  end



  def add(arg='')

    node = Node.new

    node.value = arg

    node.prev = @node_lists.last

    node.next = nil

    @node_lists.last.next = node if @node_lists.length > 0

    @node_lists << node

  end



  def find(arg)

    @node_lists.find { |node| node.value == arg }

  end

  

  def values

    @node_lists.map { |node| node.value }

  end

  

  def delete(node)

    return nil if @node_lists.empty?

    

    pos = @node_lists.index(node)

    if @node_lists[pos+1].nil? || @node_lists[pos-1].nil?

      @node_lists[pos-1].next = nil unless @node_lists[pos-1].nil?

      @node_lists[pos+1].prev = nil unless @node_lists[pos+1].nil?

    else

      @node_lists[pos-1].next = @node_lists[pos+1]

      @node_lists[pos+1].prev = @node_lists[pos-1]

    end

    

    @node_lists.delete_at(pos)

  end



end

lib/node.rb

class Node

  

  attr_accessor :value

  attr_accessor :next

  attr_accessor :prev



end