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queue/queue.cpp@11:d1f488302d06, 2014-04-25 (annotated)

Committer:
oprospero
Date:
Fri Apr 25 06:21:19 2014 +0000
Revision:
11:d1f488302d06
Parent:
7:951c71c71b2d 
small updates;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
oprospero 0:26a151d2c6db 1 /*************************** queue.cpp ***************************************/
oprospero 0:26a151d2c6db 2 /* */
oprospero 0:26a151d2c6db 3 /* Authers: Oanh Tran, Ling Lei, Sihao Xie, Greg Abdo. */
oprospero 0:26a151d2c6db 4 /* Date: February 23, 2013 */
oprospero 0:26a151d2c6db 5 /* Version: 1.0 */
oprospero 0:26a151d2c6db 6 /* */
oprospero 0:26a151d2c6db 7 /* The queue is used to stack StructureItem in order with a FILO */
oprospero 0:26a151d2c6db 8 /*arrangement. */
oprospero 0:26a151d2c6db 9 /*****************************************************************************/
oprospero 0:26a151d2c6db 10
oprospero 0:26a151d2c6db 11 #include "queue.h"
oprospero 0:26a151d2c6db 12
oprospero 0:26a151d2c6db 13 /***************************** constructor ***********************************/
oprospero 0:26a151d2c6db 14 /* Description: */
oprospero 0:26a151d2c6db 15 /*****************************************************************************/
oprospero 0:26a151d2c6db 16
oprospero 0:26a151d2c6db 17 queue::queue()
oprospero 0:26a151d2c6db 18 {
oprospero 0:26a151d2c6db 19 front = NULL; // Set front to NULL at the start.
oprospero 0:26a151d2c6db 20 }
oprospero 0:26a151d2c6db 21
oprospero 0:26a151d2c6db 22 /******************************* distructor **********************************/
oprospero 0:26a151d2c6db 23 /* Description: */
oprospero 0:26a151d2c6db 24 /*****************************************************************************/
oprospero 0:26a151d2c6db 25
oprospero 0:26a151d2c6db 26 queue::~queue()
oprospero 0:26a151d2c6db 27 {
oprospero 0:26a151d2c6db 28 clear(); // Clear the entire queue.
oprospero 0:26a151d2c6db 29 }
oprospero 0:26a151d2c6db 30
oprospero 0:26a151d2c6db 31 /*****************************************************************************/
oprospero 0:26a151d2c6db 32 /* Description: */
oprospero 0:26a151d2c6db 33 /* Accepts: */
oprospero 0:26a151d2c6db 34 /* Returns: */
oprospero 0:26a151d2c6db 35 /*****************************************************************************/
oprospero 0:26a151d2c6db 36
oprospero 0:26a151d2c6db 37 bool queue::isEmpty()
oprospero 0:26a151d2c6db 38 {
oprospero 0:26a151d2c6db 39 // Is the queue empty?
oprospero 0:26a151d2c6db 40 if( front == NULL ) // Check the front pointer.
oprospero 0:26a151d2c6db 41 return true; // Queue is empty, return true.
oprospero 0:26a151d2c6db 42
oprospero 0:26a151d2c6db 43 return false; // There is atleast one item, not empty.
oprospero 0:26a151d2c6db 44 }
oprospero 0:26a151d2c6db 45
oprospero 0:26a151d2c6db 46 /*****************************************************************************/
oprospero 0:26a151d2c6db 47 /* Description: */
oprospero 0:26a151d2c6db 48 /* Accepts: */
oprospero 0:26a151d2c6db 49 /* Returns: */
oprospero 0:26a151d2c6db 50 /*****************************************************************************/
oprospero 0:26a151d2c6db 51
oprospero 0:26a151d2c6db 52 void queue::clear()
oprospero 0:26a151d2c6db 53 {
oprospero 0:26a151d2c6db 54 // Is the list already empty?
oprospero 0:26a151d2c6db 55 if( isEmpty() ) // Check for an empty list.
oprospero 0:26a151d2c6db 56 return; // List is empty, don't need to do anything.
oprospero 0:26a151d2c6db 57
oprospero 0:26a151d2c6db 58 queueNode * current = front; // Create node to help step through list.
oprospero 0:26a151d2c6db 59 queueNode * placeHold = front; // Create node to keep place of delete.
oprospero 0:26a151d2c6db 60
oprospero 0:26a151d2c6db 61 // As long as were not at the end, keep stepping to the next node.
oprospero 0:26a151d2c6db 62 while( current != NULL)
oprospero 0:26a151d2c6db 63 {
oprospero 0:26a151d2c6db 64 placeHold = current->next; // Hold where we have to go.
oprospero 0:26a151d2c6db 65 delete current; // Delete the node.
oprospero 0:26a151d2c6db 66 current = placeHold; // Set current to the next node.
oprospero 0:26a151d2c6db 67 }
oprospero 0:26a151d2c6db 68
oprospero 0:26a151d2c6db 69 front = NULL; // Reset the front to NULL;
oprospero 0:26a151d2c6db 70 length = 0;
oprospero 0:26a151d2c6db 71 }
oprospero 0:26a151d2c6db 72
oprospero 0:26a151d2c6db 73 /*****************************************************************************/
oprospero 0:26a151d2c6db 74 /* Description: */
oprospero 0:26a151d2c6db 75 /* Accepts: */
oprospero 0:26a151d2c6db 76 /* Returns: */
oprospero 0:26a151d2c6db 77 /*****************************************************************************/
oprospero 0:26a151d2c6db 78
oprospero 0:26a151d2c6db 79 void queue::add( short * item )
oprospero 0:26a151d2c6db 80 {
oprospero 0:26a151d2c6db 81 // Were we passed an invalid object somehow?
oprospero 0:26a151d2c6db 82 if( item == NULL ) // Check for NULL
oprospero 0:26a151d2c6db 83 return; // If so, return.
oprospero 0:26a151d2c6db 84
oprospero 0:26a151d2c6db 85 if( queueLength() > MAXQUEUELENGTH )
oprospero 7:951c71c71b2d 86 delete pop();
oprospero 0:26a151d2c6db 87
oprospero 0:26a151d2c6db 88 queueNode * newNode = new queueNode( item ); // Create the new node.
oprospero 0:26a151d2c6db 89
oprospero 0:26a151d2c6db 90 if( isEmpty() )
oprospero 0:26a151d2c6db 91 front = newNode; // Set front to the new node.
oprospero 0:26a151d2c6db 92
oprospero 0:26a151d2c6db 93 else
oprospero 0:26a151d2c6db 94 {
oprospero 0:26a151d2c6db 95 queueNode *temp = front;
oprospero 0:26a151d2c6db 96 while( temp->next != NULL )
oprospero 0:26a151d2c6db 97 temp = temp->next;
oprospero 0:26a151d2c6db 98
oprospero 0:26a151d2c6db 99 temp->next = newNode;
oprospero 0:26a151d2c6db 100 }
oprospero 0:26a151d2c6db 101 length++;
oprospero 0:26a151d2c6db 102 }
oprospero 0:26a151d2c6db 103
oprospero 0:26a151d2c6db 104 /*****************************************************************************/
oprospero 0:26a151d2c6db 105 /* Description: */
oprospero 0:26a151d2c6db 106 /* Accepts: */
oprospero 0:26a151d2c6db 107 /* Returns: */
oprospero 0:26a151d2c6db 108 /*****************************************************************************/
oprospero 0:26a151d2c6db 109
oprospero 0:26a151d2c6db 110 short * queue::pop()
oprospero 0:26a151d2c6db 111 {
oprospero 0:26a151d2c6db 112 // Is the list already empty?
oprospero 0:26a151d2c6db 113 if( isEmpty() ) // Check for an empty list.
oprospero 0:26a151d2c6db 114 return NULL; // List is empty, don't need to do anything.
oprospero 0:26a151d2c6db 115
oprospero 0:26a151d2c6db 116 short* dataHold = front->data; // Keep track of what were returning.
oprospero 0:26a151d2c6db 117 queueNode * oldNode = front; // Save the old node to be deleted
oprospero 0:26a151d2c6db 118 front = front->next; // Set front to next object.
oprospero 0:26a151d2c6db 119
oprospero 0:26a151d2c6db 120 delete oldNode; // Delete the front node.
oprospero 0:26a151d2c6db 121 length--; // Remove one from the length.
oprospero 0:26a151d2c6db 122 return dataHold; // return the stuctureItem.
oprospero 0:26a151d2c6db 123 }
oprospero 0:26a151d2c6db 124
oprospero 0:26a151d2c6db 125 /*****************************************************************************/
oprospero 0:26a151d2c6db 126 /* Description: */
oprospero 0:26a151d2c6db 127 /* Accepts: */
oprospero 0:26a151d2c6db 128 /* Returns: */
oprospero 0:26a151d2c6db 129 /*****************************************************************************/
oprospero 0:26a151d2c6db 130
oprospero 0:26a151d2c6db 131 short * queue::peek()
oprospero 0:26a151d2c6db 132 {
oprospero 0:26a151d2c6db 133 if( front != NULL )
oprospero 0:26a151d2c6db 134 return front->data;
oprospero 0:26a151d2c6db 135
oprospero 0:26a151d2c6db 136 return NULL;
oprospero 0:26a151d2c6db 137 }
oprospero 0:26a151d2c6db 138
oprospero 0:26a151d2c6db 139 /*****************************************************************************/
oprospero 0:26a151d2c6db 140 /* Description: */
oprospero 0:26a151d2c6db 141 /* Accepts: */
oprospero 0:26a151d2c6db 142 /* Returns: */
oprospero 0:26a151d2c6db 143 /*****************************************************************************/
oprospero 0:26a151d2c6db 144
oprospero 0:26a151d2c6db 145 short queue::queueLength()
oprospero 0:26a151d2c6db 146 {
oprospero 0:26a151d2c6db 147 return length;
oprospero 0:26a151d2c6db 148 }