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<?php |
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namespace Ptypes; |
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use Countable; |
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use Ptypes\DLNode; |
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use Ptypes\DoublyLinkedList; |
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/** |
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* Queue |
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* Is a First In First Out (FIFO) data structure. |
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* |
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* Functions: enqueue, dequeue, peek, and size |
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*/ |
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class Queue implements Countable |
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{ |
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/** |
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* Is the doubly linked list which the queue wraps around. |
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*/ |
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private $list; |
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public function __construct() |
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{ |
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$this->list = new DoublyLinkedList(); |
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} |
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/** |
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* Enqueue |
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* Inserts the element at the tail of the queue. |
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* |
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* @param $object |
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*/ |
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public function enqueue($object) |
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{ |
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$this->list->insert_beginning(new DLNode($object)); |
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return $this; //allows chaining |
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} |
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/** |
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* Dequeue |
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* Removes the element at the head of the queue. |
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*/ |
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public function dequeue() |
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{ |
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if($this->list->size() == 0) {return $this;} |
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$this->list->remove($this->list->lastNode); |
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return $this; //allows chaining |
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} |
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/** |
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* Peek |
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* Returns the element at the head of the queue. |
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* |
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* @return object |
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*/ |
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public function peek() |
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{ |
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return $this->list->lastNode->data; |
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} |
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/** |
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* Size |
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* Gets the size of the queue. |
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* |
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* @return int |
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*/ |
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public function size() |
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{ |
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return $this->list->size(); |
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} |
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/** |
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* is_empty |
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* Determines if the queue is empty or not. |
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* |
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* @return boolean |
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*/ |
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public function is_empty() |
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{ |
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return ($this->list->size() == 0) ? true : false; |
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} |
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//Overriding functions & magic methods below |
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/** |
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* Count, same functionality as Size. |
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* Overrides the default count function call on this class. |
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* |
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* @return int |
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*/ |
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public function count() |
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{ |
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return $this->list->size(); |
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} |
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} |
HOWZ1T /
Ptypes
