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feat: Creates PrioritizedListenerProvider
New provider implements `PrioritizedListenerAttachmentInterface` and `PrioritizedListenerProviderInterface`, and will iterate attached listeners in priority order. Each iteration will take into account both the event name, if a `getName()` method is available, the event class, and any wildcard listeners, and listeners of the same priority will be returned in the order they are attached, based on those criteria.
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‎TODO-PSR-14.md

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- [x] `detachWildcardListener(callable $listener, $force = false)`
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(`detach($listener, '*', $force)` will proxy to this method)
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- [x] `clearListeners($event)`
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- [ ] Create a `PrioritizedListenerProvider` implementation of the above based
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- [x] Create a `PrioritizedListenerProvider` implementation of the above based
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on the internals of `EventManager`
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- [ ] attachment/detachment
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- [ ] getListenersForEvent should take into account event name if an EventInterface
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- [ ] getListenersForEvent should also pull wildcard listeners
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- [ ] getListenersForEvent should accept an optional second argument, an
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- [x] attachment/detachment
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- [x] getListenersForEvent should take into account event name if an EventInterface
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- [x] getListenersForEvent should also pull wildcard listeners
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- [x] getListenersForEvent should accept an optional second argument, an
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array of identifiers. This method will return all listeners in prioritized
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order.
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- [ ] implement `getListenersForEventByPriority`
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- [x] implement `getListenersForEventByPriority`
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- [ ] Create a `PrioritizedIdentifierListenerProvider` that implements
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both the `PrioritizedListenerProvider` interface and the
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`SharedEventManagerInterface`

‎src/ListenerProvider/PrioritizedListenerProvider.php

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<?php
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/**
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* @see https://github.com/zendframework/zend-eventmanager for the canonical source repository
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* @copyright Copyright (c) 2019 Zend Technologies USA Inc. (https://www.zend.com)
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* @license https://github.com/zendframework/zend-eventmanager/blob/master/LICENSE.md New BSD License
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*/
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namespace Zend\EventManager\ListenerProvider;
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use Zend\EventManager\Exception;
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class PrioritizedListenerProvider implements
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PrioritizedListenerAttachmentInterface,
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PrioritizedListenerProviderInterface
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{
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/**
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* Subscribed events and their listeners
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*
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* STRUCTURE:
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* [
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* <string name> => [
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* <int priority> => [
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* 0 => [<callable listener>, ...]
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* ],
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* ...
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* ],
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* ...
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* ]
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*
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* NOTE:
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* This structure helps us to reuse the list of listeners
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* instead of first iterating over it and generating a new one
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* -> In result it improves performance by up to 25% even if it looks a bit strange
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*
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* @var array<string, array<int, callable[]>>
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*/
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protected $events = [];
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/**
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* {@inheritDoc}
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*/
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public function getListenersForEvent($event)
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{
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yield from $this->iterateByPriority(
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$this->getListenersForEventByPriority($event)
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);
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}
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/**
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* {@inheritDoc}
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* @param string[] $identifiers Ignored in this implementation.
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* @throws Exception\InvalidArgumentException for invalid $event types.
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*/
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public function getListenersForEventByPriority($event, array $identifiers = [])
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{
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if (! is_object($event)) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s expects the $event argument to be an object; received %s',
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__METHOD__,
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gettype($event)
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));
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}
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$identifiers = is_callable([$event, 'getName'])
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? [$event->getName()]
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: [];
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$identifiers = array_merge($identifiers, [get_class($event), '*']);
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$prioritizedListeners = [];
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foreach ($identifiers as $name) {
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if (! isset($this->events[$name])) {
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continue;
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}
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foreach ($this->events[$name] as $priority => $listOfListeners) {
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$prioritizedListeners[$priority][] = $listOfListeners[0];
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}
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}
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return $prioritizedListeners;
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}
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/**
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* {@inheritDoc}
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* @throws Exception\InvalidArgumentException for invalid $event types.
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*/
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public function attach($event, callable $listener, $priority = 1)
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{
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if (! is_string($event)) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s expects a string for the event; received %s',
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__METHOD__,
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gettype($event)
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));
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}
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$this->events[$event][(int) $priority][0][] = $listener;
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}
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/**
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* {@inheritDoc}
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* @param bool $force Internal; used by attachWildcardListener to force
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* removal of the '*' event.
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* @throws Exception\InvalidArgumentException for invalid event types.
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*/
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public function detach(callable $listener, $event = null, $force = false)
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{
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if (null === $event || ('*' === $event && ! $force)) {
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$this->detachWildcardListener($listener);
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return;
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}
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if (! is_string($event)) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s expects a string for the event; received %s',
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__METHOD__,
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gettype($event)
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));
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}
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if (! isset($this->events[$event])) {
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return;
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}
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foreach ($this->events[$event] as $priority => $listeners) {
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foreach ($listeners[0] as $index => $evaluatedListener) {
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if ($evaluatedListener !== $listener) {
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continue;
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}
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// Found the listener; remove it.
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unset($this->events[$event][$priority][0][$index]);
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// If the queue for the given priority is empty, remove it.
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if (empty($this->events[$event][$priority][0])) {
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unset($this->events[$event][$priority]);
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break;
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}
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}
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}
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// If the queue for the given event is empty, remove it.
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if (empty($this->events[$event])) {
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unset($this->events[$event]);
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}
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}
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/**
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* {@inheritDoc}
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*/
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public function attachWildcardListener(callable $listener, $priority = 1)
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{
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$this->events['*'][(int) $priority][0][] = $listener;
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}
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/**
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* {@inheritDoc}
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*/
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public function detachWildcardListener(callable $listener)
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{
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foreach (array_keys($this->events) as $event) {
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$this->detach($listener, $event, true);
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}
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}
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/**
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* {@inheritDoc}
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* @throws Exception\InvalidArgumentException for invalid event types.
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*/
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public function clearListeners($event)
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{
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if (! is_string($event)) {
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throw new Exception\InvalidArgumentException(sprintf(
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'%s expects a string for the event; received %s',
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__METHOD__,
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gettype($event)
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));
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}
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if (isset($this->events[$event])) {
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unset($this->events[$event]);
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}
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}
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/**
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* @param array $prioritizedListeners
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* @return iterable
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*/
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private function iterateByPriority($prioritizedListeners)
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{
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krsort($prioritizedListeners);
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foreach ($prioritizedListeners as $listenerSets) {
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yield from $this->iterateListenerSets($listenerSets);
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}
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}
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/**
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* @param iterable $listenerSets
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* @return iterable
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*/
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private function iterateListenerSets($listenerSets)
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{
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foreach ($listenerSets as $listOfListeners) {
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yield from $listOfListeners;
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}
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}
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}

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