<?php
/**
* <p>Title: Double linked list</p>
* <p>Description: Implementation of a double linked list in PHP</p>
* @author Oddleif Halvorsen | leif-h@online.no
* @version 1.2
*/
include_once("Iterator.php");
class ListIterator extends Iterator{
/**
* Constructs a ListNode.
* @param &$head The start of the list
* @param &$list The LinkedList, nessesary for updating the size of the list on removal of nodes.
*/
function ListIterator(&$head, &$list){
parent::Iterator(&$head, &$list);
}
/**
* Checks if more nodes exist
* @return TRUE == hasNext || FALSE == no next node.
*/
function hasPrevious(){
//it has a previous value if $this->previous != NULL or current node is set an has a previous value set.
return (($this->currentNode != NULL && $this->currentNode->getPrevious() != NULL) || $this->previousNode != NULL ? TRUE : FALSE);
}
/**
* Get the reference to the previous node.
* @param &$node The next node. || FALSE if no next node exists.
*/
function getPrevious(){
if($this->hasPrevious()){
$this->currentNode = &$this->currentNode->getPrevious(); //current is the node between previous and next
$this->previousNode = &$this->currentNode->getPrevious(); //previous is the node closer to head
$this->nextNode = &$this->currentNode->getNext(); //next is the node closer to tail
return $this->currentNode->getNodeValue();
}
return FALSE;
}
}
?>
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