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 <?php
 /**
  * Zend Framework
  *
  * LICENSE
  *
  * This source file is subject to the new BSD license that is bundled
  * with this package in the file LICENSE.txt.
  * It is also available through the world-wide-web at this URL:
  * http://framework.zend.com/license/new-bsd
  * If you did not receive a copy of the license and are unable to
  * obtain it through the world-wide-web, please send an email
  * to license@zend.com so we can send you a copy immediately.
  *
  * @category   Zend
  * @package    Zend_Stdlib
  * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  */
 
 // require_once 'Zend/Stdlib/SplPriorityQueue.php';
 
 /**
  * Re-usable, serializable priority queue implementation
  *
  * SplPriorityQueue acts as a heap; on iteration, each item is removed from the
  * queue. If you wish to re-use such a queue, you need to clone it first. This 
  * makes for some interesting issues if you wish to delete items from the queue,
  * or, as already stated, iterate over it multiple times.
  *
  * This class aggregates items for the queue itself, but also composes an 
  * "inner" iterator in the form of an SplPriorityQueue object for performing
  * the actual iteration.
  *
  * @category   Zend
  * @package    Zend_Stdlib
  * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  */
 class Zend_Stdlib_PriorityQueue implements Countable, IteratorAggregate, Serializable
 {
     const EXTR_DATA     = 0x00000001;
     const EXTR_PRIORITY = 0x00000002;
     const EXTR_BOTH     = 0x00000003;
 
     /**
      * Inner queue class to use for iteration
      * @var string
      */
     protected $queueClass = 'Zend_Stdlib_SplPriorityQueue';
 
     /**
      * Actual items aggregated in the priority queue. Each item is an array
      * with keys "data" and "priority".
      * @var array
      */
     protected $items      = array();
 
     /**
      * Inner queue object
      * @var SplPriorityQueue
      */
     protected $queue;
 
     /**
      * Insert an item into the queue
      *
      * Priority defaults to 1 (low priority) if none provided.
      * 
      * @param  mixed $data 
      * @param  int $priority 
      * @return Zend_Stdlib_PriorityQueue
      */
     public function insert($data, $priority = 1)
     {
         $priority = (int) $priority;
         $this->items[] = array(
             'data'     => $data,
             'priority' => $priority,
         );
         $this->getQueue()->insert($data, $priority);
         return $this;
     }
 
     /**
      * Remove an item from the queue
      *
      * This is different than {@link extract()}; its purpose is to dequeue an
      * item.
      *
      * This operation is potentially expensive, as it requires 
      * re-initialization and re-population of the inner queue.
      * 
      * Note: this removes the first item matching the provided item found. If
      * the same item has been added multiple times, it will not remove other 
      * instances.
      *
      * @param  mixed $datum
      * @return boolean False if the item was not found, true otherwise.
      */
     public function remove($datum)
     {
         $found = false;
         foreach ($this->items as $key => $item) {
             if ($item['data'] === $datum) {
                 $found = true;
                 break;
             }
         }
         if ($found) {
             unset($this->items[$key]);
             $this->queue = null;
             $queue = $this->getQueue();
             foreach ($this->items as $item) {
                 $queue->insert($item['data'], $item['priority']);
             }
             return true;
         }
         return false;
     }
 
     /**
      * Is the queue empty?
      * 
      * @return bool
      */
     public function isEmpty()
     {
         return (0 === $this->count());
     }
 
     /**
      * How many items are in the queue?
      * 
      * @return int
      */
     public function count()
     {
         return count($this->items);
     }
 
     /**
      * Peek at the top node in the queue, based on priority.
      * 
      * @return mixed
      */
     public function top()
     {
         return $this->getIterator()->top();
     }
 
     /**
      * Extract a node from the inner queue and sift up 
      * 
      * @return mixed
      */
     public function extract()
     {
         return $this->getQueue()->extract();
     }
 
     /**
      * Retrieve the inner iterator
      *
      * SplPriorityQueue acts as a heap, which typically implies that as items
      * are iterated, they are also removed. This does not work for situations
      * where the queue may be iterated multiple times. As such, this class 
      * aggregates the values, and also injects an SplPriorityQueue. This method 
      * retrieves the inner queue object, and clones it for purposes of 
      * iteration.
      * 
      * @return SplPriorityQueue
      */
     public function getIterator()
     {
         $queue = $this->getQueue();
         return clone $queue;
     }
 
     /**
      * Serialize the data structure
      * 
      * @return string
      */
     public function serialize()
     {
         return serialize($this->items);
     }
 
     /**
      * Unserialize a string into a Zend_Stdlib_PriorityQueue object
      *
      * Serialization format is compatible with {@link Zend_Stdlib_SplPriorityQueue}
      * 
      * @param  string $data 
      * @return void
      */
     public function unserialize($data)
     {
         foreach (unserialize($data) as $item) {
             $this->insert($item['data'], $item['priority']);
         }
     }
 
     /**
      * Serialize to an array
      *
      * By default, returns only the item data, and in the order registered (not
      * sorted). You may provide one of the EXTR_* flags as an argument, allowing
      * the ability to return priorities or both data and priority.
      * 
      * @param  int $flag 
      * @return array
      */
     public function toArray($flag = self::EXTR_DATA)
     {
         switch ($flag) {
             case self::EXTR_BOTH:
                 return $this->items;
             case self::EXTR_PRIORITY:
                 return array_map(array($this, 'returnPriority'), $this->items);
             case self::EXTR_DATA:
             default:
                 return array_map(array($this, 'returnData'), $this->items);
         }
     }
 
     /**
      * Specify the internal queue class
      *
      * Please see {@link getIterator()} for details on the necessity of an
      * internal queue class. The class provided should extend SplPriorityQueue.
      * 
      * @param  string $class 
      * @return Zend_Stdlib_PriorityQueue
      */
     public function setInternalQueueClass($class)
     {
         $this->queueClass = (string) $class;
         return $this;
     }
 
     /**
      * Does the queue contain the given datum?
      * 
      * @param  mixed $datum 
      * @return bool
      */
     public function contains($datum)
     {
         foreach ($this->items as $item) {
             if ($item['data'] === $datum) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Does the queue have an item with the given priority?
      * 
      * @param  int $priority 
      * @return bool
      */
     public function hasPriority($priority)
     {
         foreach ($this->items as $item) {
             if ($item['priority'] === $priority) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Get the inner priority queue instance
      * 
      * @return Zend_Stdlib_SplPriorityQueue
      */
     protected function getQueue()
     {
         if (null === $this->queue) {
             $this->queue = new $this->queueClass();
             if (!$this->queue instanceof SplPriorityQueue) {
                 throw new DomainException(sprintf(
                     'Zend_Stdlib_PriorityQueue expects an internal queue of type SplPriorityQueue; received "%s"',
                     get_class($this->queue)
                 ));
             }
         }
         return $this->queue;
     }
 
     /**
      * Return priority from an internal item
      *
      * Used as a lambda in toArray().
      * 
      * @param  array $item 
      * @return mixed
      */
     public function returnPriority($item)
     {
         return $item['priority'];
     }
 
     /**
      * Return data from an internal item
      *
      * Used as a lambda in toArray().
      * 
      * @param  array $item 
      * @return mixed
      */
     public function returnData($item)
     {
         return $item['data'];
     }
 }