第三十六课 队列的概念及实现（上）

 1 #ifndef QUEUE_H
 2 #define QUEUE_H
 3 
 4 #include "Object.h"
 5 
 6 namespace DTLib
 7 {
 8 
 9 template < typename T >
10 class Queue : public Object
11 {
12 public:
13     virtual void add(const T& e) = 0;
14     virtual void remove() = 0;
15     virtual T front() const = 0;
16     virtual void clear() = 0;
17     virtual int length() const = 0;
18 };
19 
20 }
21 
22 #endif // QUEUE_H

 1 #ifndef STATICQUEUE_H
 2 #define STATICQUEUE_H
 3 
 4 #include "Queue.h"
 5 #include "Exception.h"
 6 
 7 namespace DTLib
 8 {
 9 
10 template < typename T, int N >
11 class StaticQueue : public Queue<T>
12 {
13 protected:
14     T m_space[N];
15     int m_front;
16     int m_rear;
17     int m_length;
18 public:
19     StaticQueue()
20     {
21         m_front = 0;
22         m_rear = 0;
23         m_length = 0;
24     }
25 
26     int capacity() const
27     {
28         return N;
29     }
30 
31     void add(const T& e)
32     {
33         if( m_length < N )
34         {
35             m_space[m_rear] = e;
36             m_rear = (m_rear + 1) % N;
37             m_length++;
38         }
39         else
40         {
41             THROW_EXCEPTION(InvalidOperationException, "No space in current queue...");
42         }
43     }
44 
45     void remove()
46     {
47         if( m_length > 0 )
48         {
49             m_front = (m_front + 1) % N;
50             m_length--;
51         }
52         else
53         {
54             THROW_EXCEPTION(InvalidOperationException, "No element in current queue...");
55         }
56     }
57 
58     T front() const
59     {
60         if( m_length > 0 )
61         {
62             return m_space[m_front];
63         }
64         else
65         {
66             THROW_EXCEPTION(InvalidOperationException, "No element in current queue...");
67         }
68     }
69 
70     void clear()
71     {
72         m_front = 0;
73         m_rear = 0;
74         m_length = 0;
75     }
76 
77     int length() const
78     {
79         return m_length;
80     }
81 
82     ~StaticQueue()
83     {
84         clear();
85     }
86 };
87 
88 }
89 
90 #endif // STATICQUEUE_H

 1 #include <iostream>
 2 #include "StaticQueue.h"
 3 
 4 using namespace std;
 5 using namespace DTLib;
 6 
 7 
 8 int main()
 9 {
10     StaticQueue<int, 5> queue;
11 
12     for(int i = 0; i < 5; i++)
13     {
14         queue.add(i);
15     }
16 
17     while( queue.length() > 0 )
18     {
19         cout << queue.front() << endl;
20 
21         queue.remove();
22     }
23 
24     return 0;
25 }