dllist.h

程序使用的是在nachos体系架构下完成双向链表的构建

#ifndef DLLIST_H
#define DLLIST_H

#include"copyright.h"
#include"utility.h"
class DLListElement {
   public:
     DLListElement(void *itemPtr, int sortKey);	// initialize a list element

     DLListElement *next;		// next element on list, 
				// NULL if this is the last
     DLListElement *prev;       // previous element on list
                                // NULL if this is the first

     int key;		    	// priority, for a sorted list
     void *item; 	    	// pointer to item on the list
};

class DLList {
  public:
    DLList();			// initialize the list
    ~DLList();			// de-allocate the list

    void Prepend(void *item); 	// add to head of list 
    void Append(void *item); 	// add to tail of list 
    void *Remove(int *keyPtr); 	// remove from head of list
                                // set *keyPtr to key of the removed item
                                // return item (or NULL if list is empty)      

    bool IsEmpty();		// return true if list has no element
    
    // Routines to put/get items on/off list in order (sorted by key)
    void SortedInsert(void *item, int sortKey);	
    void *SortedRemove(int *keyPtr); 	  // remove first item
    void Print();  
private:
    DLListElement *first;  	// Head of the list, NULL if list is empty
    DLListElement *last;	// Last element of list,NULL if empty
};
#endif