/libraries/vendor/joomla/event/src/ListenersPriorityQueue.php

  1<?php
  2/**
  3 * Part of the Joomla Framework Event Package
  4 *
  5 * @copyright  Copyright (C) 2005 - 2015 Open Source Matters, Inc. All rights reserved.
  6 * @license    GNU General Public License version 2 or later; see LICENSE
  7 */
  8
  9namespace Joomla\Event;
 10
 11use SplPriorityQueue;
 12use SplObjectStorage;
 13use IteratorAggregate;
 14use Countable;
 15
 16/**
 17 * A class containing an inner listeners priority queue that can be iterated multiple times.
 18 * One instance of ListenersPriorityQueue is used per Event in the Dispatcher.
 19 *
 20 * @since  1.0
 21 */
 22class ListenersPriorityQueue implements IteratorAggregate, Countable
 23{
 24	/**
 25	 * The inner priority queue.
 26	 *
 27	 * @var    SplPriorityQueue
 28	 *
 29	 * @since  1.0
 30	 */
 31	protected $queue;
 32
 33	/**
 34	 * A copy of the listeners contained in the queue
 35	 * that is used when detaching them to
 36	 * recreate the queue or to see if the queue contains
 37	 * a given listener.
 38	 *
 39	 * @var    SplObjectStorage
 40	 *
 41	 * @since  1.0
 42	 */
 43	protected $storage;
 44
 45	/**
 46	 * A decreasing counter used to compute
 47	 * the internal priority as an array because
 48	 * SplPriorityQueue dequeues elements with the same priority.
 49	 *
 50	 * @var    integer
 51	 *
 52	 * @since  1.0
 53	 */
 54	private $counter = PHP_INT_MAX;
 55
 56	/**
 57	 * Constructor.
 58	 *
 59	 * @since  1.0
 60	 */
 61	public function __construct()
 62	{
 63		$this->queue = new SplPriorityQueue;
 64		$this->storage = new SplObjectStorage;
 65	}
 66
 67	/**
 68	 * Add a listener with the given priority only if not already present.
 69	 *
 70	 * @param   \Closure|object  $listener  The listener.
 71	 * @param   integer          $priority  The listener priority.
 72	 *
 73	 * @return  ListenersPriorityQueue  This method is chainable.
 74	 *
 75	 * @since   1.0
 76	 */
 77	public function add($listener, $priority)
 78	{
 79		if (!$this->storage->contains($listener))
 80		{
 81			// Compute the internal priority as an array.
 82			$priority = array($priority, $this->counter--);
 83
 84			$this->storage->attach($listener, $priority);
 85			$this->queue->insert($listener, $priority);
 86		}
 87
 88		return $this;
 89	}
 90
 91	/**
 92	 * Remove a listener from the queue.
 93	 *
 94	 * @param   \Closure|object  $listener  The listener.
 95	 *
 96	 * @return  ListenersPriorityQueue  This method is chainable.
 97	 *
 98	 * @since   1.0
 99	 */
100	public function remove($listener)
101	{
102		if ($this->storage->contains($listener))
103		{
104			$this->storage->detach($listener);
105			$this->storage->rewind();
106
107			$this->queue = new SplPriorityQueue;
108
109			foreach ($this->storage as $listener)
110			{
111				$priority = $this->storage->getInfo();
112				$this->queue->insert($listener, $priority);
113			}
114		}
115
116		return $this;
117	}
118
119	/**
120	 * Tell if the listener exists in the queue.
121	 *
122	 * @param   \Closure|object  $listener  The listener.
123	 *
124	 * @return  boolean  True if it exists, false otherwise.
125	 *
126	 * @since   1.0
127	 */
128	public function has($listener)
129	{
130		return $this->storage->contains($listener);
131	}
132
133	/**
134	 * Get the priority of the given listener.
135	 *
136	 * @param   \Closure|object  $listener  The listener.
137	 * @param   mixed            $default   The default value to return if the listener doesn't exist.
138	 *
139	 * @return  mixed  The listener priority if it exists, null otherwise.
140	 *
141	 * @since   1.0
142	 */
143	public function getPriority($listener, $default = null)
144	{
145		if ($this->storage->contains($listener))
146		{
147			return $this->storage[$listener][0];
148		}
149
150		return $default;
151	}
152
153	/**
154	 * Get all listeners contained in this queue, sorted according to their priority.
155	 *
156	 * @return  object[]  An array of listeners.
157	 *
158	 * @since   1.0
159	 */
160	public function getAll()
161	{
162		$listeners = array();
163
164		// Get a clone of the queue.
165		$queue = $this->getIterator();
166
167		foreach ($queue as $listener)
168		{
169			$listeners[] = $listener;
170		}
171
172		return $listeners;
173	}
174
175	/**
176	 * Get the inner queue with its cursor on top of the heap.
177	 *
178	 * @return  SplPriorityQueue  The inner queue.
179	 *
180	 * @since   1.0
181	 */
182	public function getIterator()
183	{
184		// SplPriorityQueue queue is a heap.
185		$queue = clone $this->queue;
186
187		if (!$queue->isEmpty())
188		{
189			$queue->top();
190		}
191
192		return $queue;
193	}
194
195	/**
196	 * Count the number of listeners in the queue.
197	 *
198	 * @return  integer  The number of listeners in the queue.
199	 *
200	 * @since   1.0
201	 */
202	public function count()
203	{
204		return count($this->queue);
205	}
206}