5752106 [rkeene@sledge /home/rkeene/personal/school/comp-sci-ii/lab4]$ cat -n queue.h
  1 /* Roy Keene
  2    CS 2314
  3    Section 04
  4    Lab 04
  5    17 Sept 02
  6    queue.h
  7 
  8 */
  9 
 10 
 11 using namespace std;
 12 
 13 // File Queue.h: Header file for Queue ADT.  
 14 // Class is templated.
 15 
 16 template <typename ItemType>
 17 class QueType {
 18     public:
 19         // Class constructor.
 20         // Because there is a default constructor, the precondition that the queue
 21         // has been initialized is omitted.
 22         QueType(void);
 23         // Class destructor.
 24         ~QueType(void);
 25         // Function: Initializes the queue to an empty state.
 26         // Post: Queue is empty.
 27         void MakeEmpty(void);
 28         // Function: Determines whether the queue is empty.
 29         // Post: Function value = (queue is empty)
 30         bool IsEmpty(void) const;
 31         // Function: Determines whether the queue is full.
 32         // Post: Function value = (queue is full)
 33         bool IsFull(void) const;
 34         // Function: Adds newItem to the rear of the queue.
 35         // Pre:  Queue is not full.
 36         // Post: newItem is at the rear of the queue.
 37         void Enqueue(const ItemType &newItem);
 38         // Function: Removes front item from the queue.
 39         // Pre:  Queue is not empty.
 40         // Post: Front element has been removed from the queue.
 41         void Dequeue(void);
 42         // Function: Return the front item on the queue
 43         // Pre: Queue is not empty.
 44         // Post: Queue is unchanged, item is returned
 45         ItemType & Front(void) const;
 46         // Function: Return the next item in the list
 47         // Pre: Queue is not empty.
 48         // Post: Queue is unchanged, item is returned
 49         ItemType & Next(int reset) const;
 50     private:
 51         class NodeType {
 52             public: 
 53                 ItemType info;
 54                 NodeType* next;
 55         };    
 56         NodeType* qFront;
 57         NodeType* qRear;
 58 };
 59 
 60 
 61 
 62 template <typename ItemType> QueType<ItemType>::QueType(void) {
 63     qFront=NULL;
 64     qRear=NULL;
 65 }
 66 
 67 template <typename ItemType> void QueType<ItemType>::MakeEmpty(void) {
 68     NodeType *tmp;
 69     while (qFront) {
 70         tmp=qFront->next;
 71         delete qFront;
 72         qFront=tmp;
 73     }
 74     qRear=NULL;
 75 }
 76 
 77 template <typename ItemType> QueType<ItemType>::~QueType(void) {
 78     MakeEmpty();
 79 }
 80 
 81 
 82 template <typename ItemType> bool QueType<ItemType>::IsEmpty(void) const {
 83     return(qFront==NULL);
 84 }
 85 
 86 template <typename ItemType> bool QueType<ItemType>::IsFull(void) const {
 87     return(false);
 88 }
 89 
 90 template <typename ItemType> void QueType<ItemType>::Enqueue(const ItemType &newItem) {
 91     NodeType *newNode=new NodeType;
 92 
 93     if (IsFull()) return;
 94     newNode->info=newItem;
 95     newNode->next=NULL;
 96     if (qRear!=NULL) qRear->next=newNode;
 97     qRear=newNode;
 98     if (qFront==NULL) qFront=qRear;
 99 
100     return;
101 }
102 
103 template <typename ItemType> void QueType<ItemType>::Dequeue(void) {
104     NodeType *tmp;
105 
106     if (IsEmpty()) return;
107     tmp=qFront->next;
108     delete qFront;
109     qFront=tmp;
110     if (qFront==NULL) qRear=NULL;
111 
112     return;
113 }
114 
115 template <typename ItemType> ItemType &QueType<ItemType>::Front(void) const {
116 /* XXX: Need to throw an exception here if IsEmpty() ! */
117     return(qFront->info);
118 }
119 template <typename ItemType> ItemType &QueType<ItemType>::Next(int reset) const {
120 /* XXX: Need to throw an exception here if IsEmpty() ! */
121     static NodeType *nodeptr=qFront;
122     static ItemType tmp;
123 
124     if (reset || nodeptr==NULL) { nodeptr=qFront; return(nodeptr->info); }
125     tmp=nodeptr->info;
126     nodeptr=nodeptr->next;
127     return(tmp);
128 }
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