<?php /** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */ namespace yii\base; /** * Event is the base class for all event classes. * * It encapsulates the parameters associated with an event. * The [[sender]] property describes who raises the event. * And the [[handled]] property indicates if the event is handled. * If an event handler sets [[handled]] to be true, the rest of the * uninvoked handlers will no longer be called to handle the event. * * Additionally, when attaching an event handler, extra data may be passed * and be available via the [[data]] property when the event handler is invoked. * * @author Qiang Xue <qiang.xue@gmail.com> * @since 2.0 */ class Event extends Object { /** * @var string the event name. This property is set by [[Component::trigger()]] and [[trigger()]]. * Event handlers may use this property to check what event it is handling. */ public $name; /** * @var object the sender of this event. If not set, this property will be * set as the object whose "trigger()" method is called. * This property may also be a `null` when this event is a * class-level event which is triggered in a static context. */ public $sender; /** * @var boolean whether the event is handled. Defaults to false. * When a handler sets this to be true, the event processing will stop and * ignore the rest of the uninvoked event handlers. */ public $handled = false; /** * @var mixed the data that is passed to [[Component::on()]] when attaching an event handler. * Note that this varies according to which event handler is currently executing. */ public $data; private static $_events = []; /** * Attaches an event handler to a class-level event. * * When a class-level event is triggered, event handlers attached * to that class and all parent classes will be invoked. * * For example, the following code attaches an event handler to `ActiveRecord`'s * `afterInsert` event: * * ~~~ * Event::on(ActiveRecord::className(), ActiveRecord::EVENT_AFTER_INSERT, function ($event) { * Yii::trace(get_class($event->sender) . ' is inserted.'); * }); * ~~~ * * The handler will be invoked for EVERY successful ActiveRecord insertion. * * For more details about how to declare an event handler, please refer to [[Component::on()]]. * * @param string $class the fully qualified class name to which the event handler needs to attach. * @param string $name the event name. * @param callback $handler the event handler. * @param mixed $data the data to be passed to the event handler when the event is triggered. * When the event handler is invoked, this data can be accessed via [[Event::data]]. * @see off() */ public static function on($class, $name, $handler, $data = null) { self::$_events[$name][ltrim($class, '\\')][] = [$handler, $data]; } /** * Detaches an event handler from a class-level event. * * This method is the opposite of [[on()]]. * * @param string $class the fully qualified class name from which the event handler needs to be detached. * @param string $name the event name. * @param callback $handler the event handler to be removed. * If it is null, all handlers attached to the named event will be removed. * @return boolean whether a handler is found and detached. * @see on() */ public static function off($class, $name, $handler = null) { $class = ltrim($class, '\\'); if (empty(self::$_events[$name][$class])) { return false; } if ($handler === null) { unset(self::$_events[$name][$class]); return true; } else { $removed = false; foreach (self::$_events[$name][$class] as $i => $event) { if ($event[0] === $handler) { unset(self::$_events[$name][$class][$i]); $removed = true; } } if ($removed) { self::$_events[$name][$class] = array_values(self::$_events[$name][$class]); } return $removed; } } /** * Returns a value indicating whether there is any handler attached to the specified class-level event. * Note that this method will also check all parent classes to see if there is any handler attached * to the named event. * @param string|object $class the object or the fully qualified class name specifying the class-level event. * @param string $name the event name. * @return boolean whether there is any handler attached to the event. */ public static function hasHandlers($class, $name) { if (empty(self::$_events[$name])) { return false; } if (is_object($class)) { $class = get_class($class); } else { $class = ltrim($class, '\\'); } do { if (!empty(self::$_events[$name][$class])) { return true; } } while (($class = get_parent_class($class)) !== false); return false; } /** * Triggers a class-level event. * This method will cause invocation of event handlers that are attached to the named event * for the specified class and all its parent classes. * @param string|object $class the object or the fully qualified class name specifying the class-level event. * @param string $name the event name. * @param Event $event the event parameter. If not set, a default [[Event]] object will be created. */ public static function trigger($class, $name, $event = null) { if (empty(self::$_events[$name])) { return; } if ($event === null) { $event = new static; } $event->handled = false; $event->name = $name; if (is_object($class)) { if ($event->sender === null) { $event->sender = $class; } $class = get_class($class); } else { $class = ltrim($class, '\\'); } do { if (!empty(self::$_events[$name][$class])) { foreach (self::$_events[$name][$class] as $handler) { $event->data = $handler[1]; call_user_func($handler[0], $event); if ($event->handled) { return; } } } } while (($class = get_parent_class($class)) !== false); } }