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<?php
/**
* StatusNet, the distributed open-source microblogging tool
*
* utilities for defining and running event handlers
*
* PHP version 5
*
* LICENCE: This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* @category Event
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @copyright 2008 StatusNet, Inc.
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
* @link http://status.net/
*/
if (!defined('STATUSNET')) {
exit(1);
}
/**
* Class for events
*
* This "class" two static functions for managing events in the StatusNet code.
*
* @category Event
* @package StatusNet
* @author Evan Prodromou <evan@status.net>
* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
* @link http://status.net/
*
* @todo Define a system for using Event instances
*/
class Event {
/* Global array of hooks, mapping eventname => array of callables */
protected static $_handlers = array();
/**
* Add an event handler
*
* To run some code at a particular point in StatusNet processing.
* Named events include receiving an XMPP message, adding a new notice,
* or showing part of an HTML page.
*
* The arguments to the handler vary by the event. Handlers can return
* two possible values: false means that the event has been replaced by
* the handler completely, and no default processing should be done.
* Non-false means successful handling, and that the default processing
* should succeed. (Note that this only makes sense for some events.)
*
* Handlers can also abort processing by throwing an exception; these will
* be caught by the closest code and displayed as errors.
*
* @param string $name Name of the event
* @param callable $handler Code to run
*
* @return void
*/
public static function addHandler($name, $handler) {
if (array_key_exists($name, Event::$_handlers)) {
Event::$_handlers[$name][] = $handler;
} else {
Event::$_handlers[$name] = array($handler);
}
}
/**
* Handle an event
*
* Events are any point in the code that we want to expose for admins
* or third-party developers to use.
*
* We pass in an array of arguments (including references, for stuff
* that can be changed), and each assigned handler gets run with those
* arguments. Exceptions can be thrown to indicate an error.
*
* @param string $name Name of the event that's happening
* @param array $args Arguments for handlers
*
* @return boolean flag saying whether to continue processing, based
* on results of handlers.
*/
public static function handle($name, $args=array()) {
$result = null;
if (array_key_exists($name, Event::$_handlers)) {
foreach (Event::$_handlers[$name] as $handler) {
$result = call_user_func_array($handler, $args);
if ($result === false) {
break;
}
}
}
return ($result !== false);
}
/**
* Check to see if an event handler exists
*
* Look to see if there's any handler for a given event, or narrow
* by providing the name of a specific plugin class.
*
* @param string $name Name of the event to look for
* @param string $plugin Optional name of the plugin class to look for
*
* @return boolean flag saying whether such a handler exists
*
*/
public static function hasHandler($name, $plugin=null) {
if (array_key_exists($name, Event::$_handlers)) {
if (isset($plugin)) {
foreach (Event::$_handlers[$name] as $handler) {
if (get_class($handler[0]) == $plugin) {
return true;
}
}
} else {
return true;
}
}
return false;
}
}
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