实现自定义集合

我们可以通过实现 IEnumberable 接口和 IEnumerator 接口实现自定义集合。

 1 public class MySet : IEnumerable
 2 {
 3     internal object[] values;
 4     public MySet(object[] values)
 5     {
 6         this.values = values;
 7     }
 8     public IEnumerator GetEnumerator()
 9     {
10         return new MySetIterator(this);
11     }
12 }
13 //实现自定义迭代器：
14 public class MySetIterator : IEnumerator
15 {
16     MySet set;
17     int position;
18     internal MySetIterator(MySet set)
19     {
20         this.set = set;
21         position = -1;
22     }    
23     public object Current
24     {
25         get
26         {
27             if (position == -1 || position == set.values.Length)
28             {
29                 throw new InvalidOperationException();
30             }
31             int index = position;
32             return set.values[index];
33         }
34     }
35     public bool MoveNext()
36     {
37         if (position != set.values.Length)
38         {
39             position++;
40         }
41         return position < set.values.Length;
42     }
43     public void Reset()
44     {
45         position = -1;
46     }
47 }

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*** No matter how far you go, looking back is also necessary. ***

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