队列的C++模板实现

/*****************************************************************************
*                                    queue.h
*
* A simple queue implemented by C++ template class .
*
* Zhang Ming, 2009-10
*****************************************************************************/

#ifndef QUEUE_H
#define QUEUE_H

#include <iostream>
#include <cstdlib>

using namespace std;

namespace itlab
{

/**
* Queue Node
*/
template <typename Type>
struct LinkNode
{
Type data;
LinkNode<Type> *next;

LinkNode() : next(NULL)
{ }
LinkNode( const Type &x, LinkNode<Type> *p=NULL ) : data(x), next(p)
{ }
};

/**
* Queue
*/
template <typename Type>
class Queue
{

public:

Queue();
~Queue();

//        Queue( const Queue<Type> &rhs);
//        Queue<Type>& operator=( const Queue<Type> &rhs);

inline bool isEmpty() const;
inline void makeEmpty();

inline void enqueue( const Type &x );
inline void dequeue( Type &x );
inline void getFront( Type &x );

private:

LinkNode<Type> *front,
*rear;

inline void handleUnderflow();

};

#include <queue-impl.h>

}
// namespace itlab

#endif
// QUEUE_H

/*****************************************************************************
*                               queue-impl.h
*
* Implementation for Queue class.
*
* Zhang Ming, 2009-10
*****************************************************************************/

/**
* constructors and destructor
*/
template <typename Type>
Queue<Type>::Queue() : front(NULL), rear(NULL)
{
}

template <typename Type>
Queue<Type>::~Queue()
{
makeEmpty();
}

/**
* If the queue is empty, return true.
*/
template <typename Type>
inline bool Queue<Type>::isEmpty() const
{
return front == NULL;
}

/**
* Make the queue empty.
*/
template <typename Type>
inline void Queue<Type>::makeEmpty()
{
LinkNode<Type> *p;
while( front != NULL )
{
p = front;
front = front->next;
delete p;
}
}

/**
* Enter an element into the queue.
*/
template <typename Type>
inline void Queue<Type>::enqueue( const Type &x )
{
if( front == NULL )
{
front = rear = new LinkNode<Type>( x );
if( !front )
{
cerr << "Out of memory!" << endl;
exit( 1 );
}
}
else
{
rear->next = new LinkNode<Type>( x );
if( !rear )
{
cerr << "Out of memory!" << endl;
exit( 1 );
}
rear = rear->next;
}
}

/**
* Pop an element from the queue.
*/
template <typename Type>
inline void Queue<Type>::dequeue( Type &x )
{
if( !isEmpty() )
{
LinkNode<Type> *p = front;
x = front->data;
front = front->next;
delete p;
}
else
handleUnderflow();
}

/**
* Get the front element of the queue.
*/
template <typename Type>
inline void Queue<Type>::getFront( Type &x )
{
if( !isEmpty() )
x = front->data;
else
handleUnderflow();
}

/**
* Handle the error of get element from an empty queue.
*/
template <typename Type>
inline void Queue<Type>::handleUnderflow()
{
cerr << "The queue is empty!" << endl << endl;
exit( 1 );
}

/*****************************************************************************
*                               queue_test.cpp
*
* Queue class testing.
*
* Zhang Ming, 2009-10
*****************************************************************************/

#include <iostream>
#include <string>
#include <queue.h>

using namespace std;
using namespace itlab;

struct Student
{
int     stuNum;
string  stuName;
string  department;

Student( int number = 0, const string &name = "Tom&Jerry",
const string &dpt = "Information" )
: stuNum(number), stuName(name), department(dpt)
{ }

};

int main()
{
Student stu;
Queue<Student> q;

q.enqueue( Student(11, "ZhangMing", "Information") );
q.enqueue( Student(16, "HuZhaoJun") );
q.enqueue( Student(11, "ZhangYuYang", "AutoControl") );
q.enqueue( Student() );

q.getFront( stu );
cout << "  " << stu.stuNum << "\t" << stu.stuName << "\t"
<< stu.department << endl;

cout << endl;
while( !q.isEmpty() )
{
q.dequeue( stu );
cout << "  " << stu.stuNum << "\t" << stu.stuName << "\t"
<< stu.department << endl;
}
cout << endl;

q.getFront( stu );
cout << "  " << stu.stuNum << "\t" << stu.stuName << "\t"
<< stu.department;

cout << endl << endl;
return 0;
}