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