红宝石：想要一个集合类对象，preserves秩序 [英] Ruby: Want a Set-like object which preserves order

问题描述

...或替代其中prevents重复项的Array。

... or alternatively an Array which prevents duplicate entries.

是否有某种Ruby中其中的对象：

• 响应[]，[] =和＆lt;＆LT;


• 默默滴重复的条目
  
• 可枚举（或至少支持find_all）
  
• preserves在哪些条目已插入的顺序
  

  Is there some kind of object in Ruby which:

  • responds to [], []= and <<
  • silently drops duplicate entries
  • is Enumerable (or at least supports find_all)
  • preserves the order in which entries were inserted

    据我所知，一个阵列支持要点1，3和4;而一组支持1，2和3（而不是4）。而如果SortedSet不会做，因为我的作品没有实现＆LT; =>

    As far as I can tell, an Array supports points 1, 3 and 4; while a Set supports 1, 2 and 3 (but not 4). And a SortedSet won't do, because my entries don't implement <=>.

    推荐答案

    没有一个，据我所知，并由其数学性质设置是为了是无序的（或至少，implementationally，并不是为了保障为了 - 事实上它通常被实现为一个哈希表，因此不弄乱顺序）

    There isn't one as far as I know, and Set by its mathematical nature is meant to be unordered (or at least, implementationally, meant not to guarantee order - in fact its usually implemented as a hash table so it does mess up order).

    然而，这并不难直接延长数组或继承它做到这一点。我只是想出来，这个作品：

    However, it's not hard to either extend array directly or subclass it to do this. I just tried it out and this works:

    class UniqueArray < Array
      def initialize(*args)
        if args.size == 1 and args[0].is_a? Array then
          super(args[0].uniq)
        else
          super(*args)
        end
      end
    
      def insert(i, v)
        super(i, v) unless include?(v)
      end
    
      def <<(v)
        super(v) unless include?(v)
      end
    
      def []=(*args)
        # note: could just call super(*args) then uniq!, but this is faster
    
        # there are three different versions of this call:
        # 1. start, length, value
        # 2. index, value
        # 3. range, value
        # We just need to get the value
        v = case args.size
          when 3 then args[2]
          when 2 then args[1]
          else nil
        end
    
        super(*args) if v.nil? or not include?(v)
      end
    end
    

    似乎涵盖所有的基础。我用奥莱利的得心应手红宝石食谱作为参考 - 他们有一个确保一个有序数组排序保持，这是类似配方

    Seems to cover all the bases. I used OReilly's handy Ruby Cookbook as a reference - they have a recipe for "Making sure a sorted array stays sorted" which is similar.

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