PHP implements queue (Queue) data structure_PHP tutorial

Queue is a special first-in-first-out linear table that can only perform deletion operations on the front end (commonly called dequeuing) and insertion operations on the backend (commonly called enqueuing). The end that performs the deletion operation is called the head of the queue, and the end that performs the insertion operation is called the tail of the queue. Queue organizes data according to the first-in-first-out or last-in-last-out principle. When there are no elements in the queue, it is called an empty queue.

Data structure and algorithm (PHP implementation) - Queue (Queue) 1
/**
* Data structure and algorithm (PHP implementation) - Queue (Queue).
*
* @author Chuangxiang Programming (TOPPHP.ORG)
* @copyright Copyright (c) 2013 TOPPHP.ORG All Rights Reserved
* @license http://www.opensource.org/licenses/mit-license.php MIT LICENSE
* @version 1.0.0 - Build20130607
​*/
class Queue {
/**
* Queue.
*
* @var array
​*/
private $queue;

/**
* The length of the queue.
*
* @var integer
​*/
private $size;

/**
*Construction method - initialize data.
​*/
public function __construct() {
$this->queue = array();
$this->size = 0;
}

/**
* Join the team operation.
*
* @param mixed $data enqueued data.
* @return object Returns the object itself.
​*/
public function enqueue($data) {
$this->queue[$this->size++] = $data;

Return $this;
}

/**
* Dequeue operation.
*
* @return mixed Returns FALSE when the queue is empty, otherwise returns the head element of the queue.
​*/
public function dequeue() {
If (!$this->isEmpty()) {
--$this->size;
$front = array_splice($this->queue, 0, 1);

Return $front[0];
}

Return FALSE;
}

/**
* Get the queue.
*
* @return array Returns the entire queue.
​*/
public function getQueue() {
Return $this->queue;
}

/**
* Get the head element of the team.
*
* @return mixed Returns FALSE when the queue is empty, otherwise returns the head element of the queue.
​*/
public function getFront() {
If (!$this->isEmpty()) {
Return $this->queue[0];
}

Return FALSE;
}

/**
* Get the length of the queue.
*
* @return integer Returns the length of the queue.
​*/
public function getSize() {
Return $this->size;
}

/**
* Check whether the queue is empty.
*
* @return boolean Returns TRUE if the queue is empty, otherwise returns FALSE.
​*/
public function isEmpty() {
Return 0 === $this->size;
}
}
?>

Sample code 1
$queue = new Queue();
$queue->enqueue(1)->enqueue(2)->enqueue(3)->enqueue(4)->enqueue(5)->enqueue(6);
echo '

', print_r($queue->getQueue(), TRUE), '

';

$queue->dequeue();
echo '

', print_r($queue->getQueue(), TRUE), '

';
?>

Note: PHP array functions already have queue-like functions: array_unshift (enqueue) and array_shift (dequeue).

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