c++ 行为型模式-迭代器(Iterator)

  1 #include <iostream>
  2 typedef int DATE;
  3 class Iterator
  4 {
  5 public:
  6     Iterator() {}
  7     virtual ~Iterator() {}
  8     virtual void First() = 0;       // 迭代器归零
  9     virtual void Next() = 0;        // 迭代器指向下一个
 10     virtual bool IsDone() = 0;        // 迭代器已指向最后一个元素
 11     virtual DATE Currentltem() = 0; // 迭代器当前指向的元素
 12 };
 13 
 14 class Aggregate
 15 {
 16 public:
 17     Aggregate() {};
 18     virtual ~Aggregate() {}
 19     virtual Iterator* CreateIterator() = 0;
 20     virtual int getSize() = 0;
 21     virtual DATE getItem(int index) = 0;
 22     virtual void push_back(DATE date) = 0;
 23 };
 24 class ConcreteIterator : public Iterator
 25 {
 26 public:
 27     ConcreteIterator(Aggregate* ptr) : m_pAggregate(ptr) 
 28         ,m_index(0)
 29     {
 30     }
 31     virtual ~ConcreteIterator() {}
 32     virtual void First()
 33     {
 34         m_index = 0;
 35     }
 36     virtual void Next()
 37     {
 38         m_index++;
 39     }
 40     virtual bool IsDone()
 41     {
 42         if (m_index == m_pAggregate->getSize())
 43         {
 44             return true;
 45         }
 46         return false;
 47     }
 48     virtual DATE Currentltem()
 49     {
 50         return m_pAggregate->getItem(m_index);
 51     }
 52 private:
 53     int m_index;
 54     Aggregate* m_pAggregate;
 55 };
 56 class ConcreteAggregate : public Aggregate
 57 {
 58 public:
 59     ConcreteAggregate(int num) : m_size(num), m_index(0)
 60     {
 61         m_start = new DATE[num];
 62     }
 63     virtual ~ConcreteAggregate() 
 64     {
 65         delete[] m_start;
 66      }
 67     virtual Iterator* CreateIterator()
 68     {
 69         return new ConcreteIterator(this);
 70     }
 71     void push_back(DATE date)
 72     {
 73         if (m_index < m_size)
 74         {
 75             *(m_start+m_index) = date;
 76             m_index++;
 77         }
 78     }
 79     virtual int getSize()
 80     {
 81         return m_index;
 82     }
 83     virtual DATE getItem(int index)
 84     {
 85         return *(DATE*)(m_start+index);
 86     }
 87 private:
 88     DATE* m_start;            // 目前使用空间的头
 89     int m_index;            
 90     int m_size;                // 申请空间长度
 91 };
 92 
 93 int main() 
 94 {
 95     Aggregate* pAggregate = new ConcreteAggregate(2);
 96 
 97     pAggregate->push_back(1);
 98     pAggregate->push_back(2);
 99     Iterator* iter = new ConcreteIterator(pAggregate);
100     for (; !iter->IsDone(); iter->Next())
101     {
102         std::cout << iter->Currentltem() << std::endl;
103     }
104     delete pAggregate;
105     delete iter;
106     system("pause");
107 }