Iterator Pattern

1.Iterator模式用来解决对一个聚合对象的遍历问题，将对聚合的遍历封装到一个类中进行，这样就避免了暴露这个聚合对象的内部表示的可能.

2.Iterator 模式结构图

3.实现

 1 #ifndef _AGGREGATE_H_ 
 2 #define _AGGREGATE_H_
 3 
 4 class Iterator;
 5 typedef int Object;
 6 class Interator;
 7 
 8 class Aggregate 
 9 { 
10 public: 
11     virtual ~Aggregate();
12     virtual Iterator* CreateIterator() = 0;
13     virtual Object GetItem(int idx) = 0;
14     virtual int GetSize() = 0;
15 
16 protected: 
17     Aggregate();
18 
19 private:
20 };
21 
22 class ConcreteAggregate:public Aggregate 
23 {
24 public: 
25     enum 
26     {
27         SIZE = 3
28     };    
29     ConcreteAggregate();
30     ~ConcreteAggregate();
31     Iterator* CreateIterator();
32     Object GetItem(int idx);
33     int GetSize();
34 
35 protected:
36 private: 
37     Object _objs[SIZE];
38 };
39 
40 #endif

Aggregate.h