<?php declare(strict_types=1);

/*
 * This file is part of Composer.
 *
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Composer\EventDispatcher;

/**
 * An EventSubscriber knows which events it is interested in.
 *
 * If an EventSubscriber is added to an EventDispatcher, the manager invokes
 * {@link getSubscribedEvents} and registers the subscriber as a listener for all
 * returned events.
 *
 * @author Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @author Jonathan Wage <jonwage@gmail.com>
 * @author Roman Borschel <roman@code-factory.org>
 * @author Bernhard Schussek <bschussek@gmail.com>
 */
interface EventSubscriberInterface
{
    /**
     * Returns an array of event names this subscriber wants to listen to.
     *
     * The array keys are event names and the value can be:
     *
     * * The method name to call (priority defaults to 0)
     * * An array composed of the method name to call and the priority
     * * An array of arrays composed of the method names to call and respective
     *   priorities, or 0 if unset
     *
     * For instance:
     *
     * * array('eventName' => 'methodName')
     * * array('eventName' => array('methodName', $priority))
     * * array('eventName' => array(array('methodName1', $priority), array('methodName2'))
     *
     * @return array<string, string|array{0: string, 1?: int}|array<array{0: string, 1?: int}>> The event names to listen to
     */
    public static function getSubscribedEvents();
}
