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   1  <?php
   2  namespace GuzzleHttp\Event;
   3  
   4  /**
   5   * Guzzle event emitter.
   6   *
   7   * Some of this class is based on the Symfony EventDispatcher component, which
   8   * ships with the following license:
   9   *
  10   *     This file is part of the Symfony package.
  11   *
  12   *     (c) Fabien Potencier <fabien@symfony.com>
  13   *
  14   *     For the full copyright and license information, please view the LICENSE
  15   *     file that was distributed with this source code.
  16   *
  17   * @link https://github.com/symfony/symfony/tree/master/src/Symfony/Component/EventDispatcher
  18   */
  19  class Emitter implements EmitterInterface
  20  {
  21      /** @var array */
  22      private $listeners = [];
  23  
  24      /** @var array */
  25      private $sorted = [];
  26  
  27      public function on($eventName, callable $listener, $priority = 0)
  28      {
  29          if ($priority === 'first') {
  30              $priority = isset($this->listeners[$eventName])
  31                  ? max(array_keys($this->listeners[$eventName])) + 1
  32                  : 1;
  33          } elseif ($priority === 'last') {
  34              $priority = isset($this->listeners[$eventName])
  35                  ? min(array_keys($this->listeners[$eventName])) - 1
  36                  : -1;
  37          }
  38  
  39          $this->listeners[$eventName][$priority][] = $listener;
  40          unset($this->sorted[$eventName]);
  41      }
  42  
  43      public function once($eventName, callable $listener, $priority = 0)
  44      {
  45          $onceListener = function (
  46              EventInterface $event
  47          ) use (&$onceListener, $eventName, $listener, $priority) {
  48              $this->removeListener($eventName, $onceListener);
  49              $listener($event, $eventName);
  50          };
  51  
  52          $this->on($eventName, $onceListener, $priority);
  53      }
  54  
  55      public function removeListener($eventName, callable $listener)
  56      {
  57          if (empty($this->listeners[$eventName])) {
  58              return;
  59          }
  60  
  61          foreach ($this->listeners[$eventName] as $priority => $listeners) {
  62              if (false !== ($key = array_search($listener, $listeners, true))) {
  63                  unset(
  64                      $this->listeners[$eventName][$priority][$key],
  65                      $this->sorted[$eventName]
  66                  );
  67              }
  68          }
  69      }
  70  
  71      public function listeners($eventName = null)
  72      {
  73          // Return all events in a sorted priority order
  74          if ($eventName === null) {
  75              foreach (array_keys($this->listeners) as $eventName) {
  76                  if (empty($this->sorted[$eventName])) {
  77                      $this->listeners($eventName);
  78                  }
  79              }
  80              return $this->sorted;
  81          }
  82  
  83          // Return the listeners for a specific event, sorted in priority order
  84          if (empty($this->sorted[$eventName])) {
  85              $this->sorted[$eventName] = [];
  86              if (isset($this->listeners[$eventName])) {
  87                  krsort($this->listeners[$eventName], SORT_NUMERIC);
  88                  foreach ($this->listeners[$eventName] as $listeners) {
  89                      foreach ($listeners as $listener) {
  90                          $this->sorted[$eventName][] = $listener;
  91                      }
  92                  }
  93              }
  94          }
  95  
  96          return $this->sorted[$eventName];
  97      }
  98  
  99      public function hasListeners($eventName)
 100      {
 101          return !empty($this->listeners[$eventName]);
 102      }
 103  
 104      public function emit($eventName, EventInterface $event)
 105      {
 106          if (isset($this->listeners[$eventName])) {
 107              foreach ($this->listeners($eventName) as $listener) {
 108                  $listener($event, $eventName);
 109                  if ($event->isPropagationStopped()) {
 110                      break;
 111                  }
 112              }
 113          }
 114  
 115          return $event;
 116      }
 117  
 118      public function attach(SubscriberInterface $subscriber)
 119      {
 120          foreach ($subscriber->getEvents() as $eventName => $listeners) {
 121              if (is_array($listeners[0])) {
 122                  foreach ($listeners as $listener) {
 123                      $this->on(
 124                          $eventName,
 125                          [$subscriber, $listener[0]],
 126                          isset($listener[1]) ? $listener[1] : 0
 127                      );
 128                  }
 129              } else {
 130                  $this->on(
 131                      $eventName,
 132                      [$subscriber, $listeners[0]],
 133                      isset($listeners[1]) ? $listeners[1] : 0
 134                  );
 135              }
 136          }
 137      }
 138  
 139      public function detach(SubscriberInterface $subscriber)
 140      {
 141          foreach ($subscriber->getEvents() as $eventName => $listener) {
 142              $this->removeListener($eventName, [$subscriber, $listener[0]]);
 143          }
 144      }
 145  }