ruby trie实现参考问题

我试图在Ruby中实现一个trie,但无法找出我的 print collect 方法。

我想问题可能是Ruby是通过引用传递的(不像JS),以及变量赋值在Ruby中是如何工作的。

所以如果我用 string.clone 收集 函数,然后我得到:

["peter", "peter", "petera", "pdanny", "pdjane", "pdjanck"]

如果我通过 string 然后:

["peterradannyjaneck", "peterradannyjaneck", "peterradannyjaneck", "peterradannyjaneck", "peterradannyjaneck", "peterradannyjaneck"]

代码:

class Node
  attr_accessor :hash, :end_node, :data

  def initialize
    @hash = {}
    @end_node = false
    @data = data
  end

  def end_node?
    end_node
  end
end

class Trie
  def initialize
    @root = Node.new
    @words = []
  end

  def add(input, data, node = @root)
    if input.empty?
      node.data = data
      node.end_node = true
    elsif node.hash.keys.include?(input[0])
      add(input[1..-1], data, node.hash[input[0]])
    else
      node.hash[input[0]] = Node.new
      add(input[1..-1], data, node.hash[input[0]])
    end
  end

  def print(node = @root)
    collect(node, '')
    @words
  end

  private

  def collect(node, string)
    if node.hash.size > 0
      for letter in node.hash.keys
        string = string.concat(letter)
        collect(node.hash[letter], string.clone)
      end

      @words << string if node.end_node?
    else
      string.length > 0 ? @words << string : nil
    end 
  end
end

trie = Trie.new
trie.add('peter', date: '1988-02-26')
trie.add('petra', date: '1977-02-12')
trie.add('danny', date: '1998-04-21')
trie.add('jane', date: '1985-05-08')
trie.add('jack', date: '1994-11-04')
trie.add('pete', date: '1977-12-18')
print trie.print