Dispatcher.php

<?php
namespace Darya\Events;

/**
 * Darya's event dispatcher implementation.
 *
 * @author Chris Andrew <chris@hexus.io>
 */
class Dispatcher implements Dispatchable, Subscribable
{
	/**
	 * Keys are event names and values are callables.
	 *
	 * @var array
	 */
	protected $listeners;

	/**
	 * Ensure that a listeners array exists for the given event.
	 *
	 * @param string $event
	 */
	protected function touch($event)
	{
		if (!isset($this->listeners[$event])) {
			$this->listeners[$event] = array();
		}
	}

	/**
	 * Register a listener with the given event.
	 *
	 * @param string   $event
	 * @param callable $callable
	 * @return void
	 */
	public function listen($event, $callable)
	{
		$this->touch($event);

		$this->listeners[$event][] = $callable;
	}

	/**
	 * Unregister a listener from the given event.
	 *
	 * @param string   $event
	 * @param callable $callable
	 */
	public function unlisten($event, $callable)
	{
		$this->touch($event);

		$this->listeners[$event] = array_filter($this->listeners[$event], function ($value) use ($callable) {
			return $value !== $callable;
		});
	}

	/**
	 * Register the given subscriber's event listeners.
	 *
	 * @param Subscriber $subscriber
	 */
	public function subscribe(Subscriber $subscriber)
	{
		$subscriptions = $subscriber->getEventSubscriptions();

		foreach ($subscriptions as $event => $listener) {
			$this->listen($event, $listener);
		}
	}

	/**
	 * Unregister the given subscriber's event listeners.
	 *
	 * @param Subscriber $subscriber
	 */
	public function unsubscribe(Subscriber $subscriber)
	{
		$subscriptions = $subscriber->getEventSubscriptions();

		foreach ($subscriptions as $event => $listener) {
			$this->unlisten($event, $listener);
		}
	}

	/**
	 * Dispatch the given event.
	 *
	 * Optionally accepts arguments to pass to the event's registered listeners.
	 *
	 * @param string $event
	 * @param array  $arguments [optional]
	 * @return array
	 */
	public function dispatch($event, array $arguments = array())
	{
		$this->touch($event);

		$results = array();

		foreach ((array) $this->listeners[$event] as $listener) {
			if (is_callable($listener)) {
				$results[] = call_user_func_array($listener, $arguments);
			}
		}

		return $results;
	}
}