Viewing file:  double_link_example.php (2.87 KB) -rw-r--r--
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<?php
require 'Structures/LinkedList/Double.php';
/* To do anything useful with a linked list, you need to
* extend the Node class to hold data associated with the
* node. In this case, we're just going to hold a single
* integer in the $_my_number property.
*/
class LinkNodeTester extends Structures_LinkedList_DoubleNode {
protected $_my_number;
protected $_my_letter;
function __construct($number, $letter) {
$this->_my_number = $number;
$this->_my_letter = $letter;
}
function getNumber() {
return $this->_my_number;
}
function getLetter() {
return $this->_my_letter;
}
function setNumb($number) {
$this->_my_number = $number;
}
function __toString() {
return "{$this->getNumber()}";
}
}
/* To enable key=>value iteration, we must override the default key()
* method in Structures_LinkedList_Double to return a meaningful value */
class LinkListTester extends Structures_LinkedList_Double {
function key() {
return $this->current()->getLetter();
}
}
/* Now we'll create some instances of the new class */
$node1 = new LinkNodeTester(1, 'a');
$node2 = new LinkNodeTester(2, 'b');
$node3 = new LinkNodeTester(3, 'c');
$node4 = new LinkNodeTester(4, 'd');
$node5 = new LinkNodeTester(5, 'e');
/* Start by instantiating a list object.
* You can either pass the first node to the constructor,
* or leave it null and add nodes later.
*/
$list = new LinkListTester($node1); // 1
/* appendNode() adds a node to the end of the list */
$list->appendNode($node2); // 1-2
/* prependNode() adds a node to the start of the list */
$list->prependNode($node3); // 3-1-2
/* insertNode($new_node, $reference_node, $before) adds a node
* before the reference node if the third parameter is true,
* or after the reference node if the third parameter is false
*/
$list->insertNode($node4, $node1); // 3-1-4-2
$list->insertNode($node5, $node1, true); // 3-5-1-4-2
/* current() returns the current pointer node in the list */
$link = $list->current();
print $link->getNumber(); // "1"
/* rewind() resets the pointer to the root node of the list */
$link = $list->rewind();
print $link->getNumber(); // "3"
// iterate through the list with do...while()
do {
print $link->getNumber();
} while ($link = $list->next()); // "35142"
/* You can also iterate through a list with foreach() */
foreach ($list as $bull) {
print $bull->getNumber();
} // 3-1-4-2
/* Override the key() method to enable $key=>$value iteration */
foreach ($list as $key=>$value) {
print "$key => $value\n";
}
/* end() resets the pointer to the last node of the list */
$link = $list->end();
print $link->getNumber(); // "2"
/* You can iterate backwards through a list with previous() */
do {
print $link->getNumber();
} while ($link = $list->previous()); // "24153"
?>
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