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   1  <?php
   2  /**
   3   * Part of the Joomla Framework Event Package
   4   *
   5   * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
   6   * @license    GNU General Public License version 2 or later; see LICENSE
   7   */
   8  
   9  namespace Joomla\Event;
  10  
  11  /**
  12   * A class containing an inner listeners priority queue that can be iterated multiple times.
  13   *
  14   * @since  1.0
  15   * @internal
  16   */
  17  final class ListenersPriorityQueue implements \IteratorAggregate, \Countable
  18  {
  19      /**
  20       * The listeners for an event.
  21       *
  22       * @var    array
  23       * @since  2.0.0
  24       */
  25      private $listeners = [];
  26  
  27      /**
  28       * Add a listener with the given priority only if not already present.
  29       *
  30       * @param   callable  $callback  A callable function acting as an event listener.
  31       * @param   integer   $priority  The listener priority.
  32       *
  33       * @return  $this
  34       *
  35       * @since   1.0
  36       */
  37  	public function add(callable $callback, int $priority): self
  38      {
  39          $this->listeners[$priority][] = $callback;
  40  
  41          return $this;
  42      }
  43  
  44      /**
  45       * Remove a listener from the queue.
  46       *
  47       * @param   callable  $callback  A callable function acting as an event listener.
  48       *
  49       * @return  $this
  50       *
  51       * @since   1.0
  52       */
  53  	public function remove(callable $callback): self
  54      {
  55          foreach ($this->listeners as $priority => $listeners)
  56          {
  57              if (($key = array_search($callback, $listeners, true)) !== false)
  58              {
  59                  unset($this->listeners[$priority][$key]);
  60              }
  61          }
  62  
  63          return $this;
  64      }
  65  
  66      /**
  67       * Tell if the listener exists in the queue.
  68       *
  69       * @param   callable  $callback  A callable function acting as an event listener.
  70       *
  71       * @return  boolean  True if it exists, false otherwise.
  72       *
  73       * @since   1.0
  74       */
  75  	public function has(callable $callback): bool
  76      {
  77          foreach ($this->listeners as $priority => $listeners)
  78          {
  79              if (($key = array_search($callback, $listeners, true)) !== false)
  80              {
  81                  return true;
  82              }
  83          }
  84  
  85          return false;
  86      }
  87  
  88      /**
  89       * Get the priority of the given listener.
  90       *
  91       * @param   callable  $callback  A callable function acting as an event listener.
  92       * @param   mixed     $default   The default value to return if the listener doesn't exist.
  93       *
  94       * @return  mixed  The listener priority if it exists or the specified default value
  95       *
  96       * @since   1.0
  97       */
  98  	public function getPriority(callable $callback, $default = null)
  99      {
 100          foreach ($this->listeners as $priority => $listeners)
 101          {
 102              if (($key = array_search($callback, $listeners, true)) !== false)
 103              {
 104                  return $priority;
 105              }
 106          }
 107  
 108          return $default;
 109      }
 110  
 111      /**
 112       * Get all listeners contained in this queue, sorted according to their priority.
 113       *
 114       * @return  callable[]  An array of listeners.
 115       *
 116       * @since   1.0
 117       */
 118  	public function getAll(): array
 119      {
 120          if (empty($this->listeners))
 121          {
 122              return [];
 123          }
 124  
 125          krsort($this->listeners);
 126  
 127          return \call_user_func_array('array_merge', $this->listeners);
 128      }
 129  
 130      /**
 131       * Get the priority queue.
 132       *
 133       * @return  \ArrayIterator
 134       *
 135       * @since   1.0
 136       */
 137      #[\ReturnTypeWillChange]
 138  	public function getIterator()
 139      {
 140          return new \ArrayIterator($this->getAll());
 141      }
 142  
 143      /**
 144       * Count the number of listeners in the queue.
 145       *
 146       * @return  integer  The number of listeners in the queue.
 147       *
 148       * @since   1.0
 149       */
 150      #[\ReturnTypeWillChange]
 151  	public function count()
 152      {
 153          $count = 0;
 154  
 155          foreach ($this->listeners as $priority)
 156          {
 157              $count += \count($priority);
 158          }
 159  
 160          return $count;
 161      }
 162  }