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<?php
/**
* DokuWiki Events
*
* @license GPL 2 (http://www.gnu.org/licenses/gpl.html)
* @author Christopher Smith <chris@jalakai.co.uk>
*/
if(!defined('DOKU_INC')) die('meh.');
class Doku_Event {
// public properties
var $name = ''; // READONLY event name, objects must register against this name to see the event
var $data = null; // READWRITE data relevant to the event, no standardised format (YET!)
var $result = null; // READWRITE the results of the event action, only relevant in "_AFTER" advise
// event handlers may modify this if they are preventing the default action
// to provide the after event handlers with event results
var $canPreventDefault = true; // READONLY if true, event handlers can prevent the events default action
// private properties, event handlers can effect these through the provided methods
var $_default = true; // whether or not to carry out the default action associated with the event
var $_continue = true; // whether or not to continue propagating the event to other handlers
/**
* event constructor
*/
function Doku_Event($name, &$data) {
$this->name = $name;
$this->data =& $data;
}
/**
* advise functions
*
* advise all registered handlers of this event
*
* if these methods are used by functions outside of this object, they must
* properly handle correct processing of any default action and issue an
* advise_after() signal. e.g.
* $evt = new Doku_Event(name, data);
* if ($evt->advise_before(canPreventDefault) {
* // default action code block
* }
* $evt->advise_after();
* unset($evt);
*
* @return results of processing the event, usually $this->_default
*/
function advise_before($enablePreventDefault=true) {
global $EVENT_HANDLER;
$this->canPreventDefault = $enablePreventDefault;
$EVENT_HANDLER->process_event($this,'BEFORE');
return (!$enablePreventDefault || $this->_default);
}
function advise_after() {
global $EVENT_HANDLER;
$this->_continue = true;
$EVENT_HANDLER->process_event($this,'AFTER');
}
/**
* trigger
*
* - advise all registered (<event>_BEFORE) handlers that this event is about to take place
* - carry out the default action using $this->data based on $enablePrevent and
* $this->_default, all of which may have been modified by the event handlers.
* - advise all registered (<event>_AFTER) handlers that the event has taken place
*
* @return $event->results
* the value set by any <event>_before or <event> handlers if the default action is prevented
* or the results of the default action (as modified by <event>_after handlers)
* or NULL no action took place and no handler modified the value
*/
function trigger($action=null, $enablePrevent=true) {
if (!is_callable($action)) $enablePrevent = false;
if ($this->advise_before($enablePrevent) && is_callable($action)) {
if (is_array($action)) {
list($obj,$method) = $action;
$this->result = $obj->$method($this->data);
} else {
$this->result = $action($this->data);
}
}
$this->advise_after();
return $this->result;
}
/**
* stopPropagation
*
* stop any further processing of the event by event handlers
* this function does not prevent the default action taking place
*/
function stopPropagation() { $this->_continue = false; }
/**
* preventDefault
*
* prevent the default action taking place
*/
function preventDefault() { $this->_default = false; }
}
class Doku_Event_Handler {
// public properties: none
// private properties
var $_hooks = array(); // array of events and their registered handlers
/**
* event_handler
*
* constructor, loads all action plugins and calls their register() method giving them
* an opportunity to register any hooks they require
*/
function Doku_Event_Handler() {
// load action plugins
$plugin = null;
$pluginlist = plugin_list('action');
foreach ($pluginlist as $plugin_name) {
$plugin =& plugin_load('action',$plugin_name);
if ($plugin !== null) $plugin->register($this);
}
}
/**
* register_hook
*
* register a hook for an event
*
* @param $event (string) name used by the event, (incl '_before' or '_after' for triggers)
* @param $obj (obj) object in whose scope method is to be executed,
* if NULL, method is assumed to be a globally available function
* @param $method (function) event handler function
* @param $param (mixed) data passed to the event handler
*/
function register_hook($event, $advise, &$obj, $method, $param=null) {
$this->_hooks[$event.'_'.$advise][] = array(&$obj, $method, $param);
}
function process_event(&$event,$advise='') {
$evt_name = $event->name . ($advise ? '_'.$advise : '_BEFORE');
if (!empty($this->_hooks[$evt_name])) {
$hook = reset($this->_hooks[$evt_name]);
do {
// list($obj, $method, $param) = $hook;
$obj =& $hook[0];
$method = $hook[1];
$param = $hook[2];
if (is_null($obj)) {
$method($event, $param);
} else {
$obj->$method($event, $param);
}
} while ($event->_continue && $hook = next($this->_hooks[$evt_name]));
}
}
}
/**
* trigger_event
*
* function wrapper to process (create, trigger and destroy) an event
*
* @param $name (string) name for the event
* @param $data (mixed) event data
* @param $action (callback) (optional, default=NULL) default action, a php callback function
* @param $canPreventDefault (bool) (optional, default=true) can hooks prevent the default action
*
* @return (mixed) the event results value after all event processing is complete
* by default this is the return value of the default action however
* it can be set or modified by event handler hooks
*/
function trigger_event($name, &$data, $action=null, $canPreventDefault=true) {
$evt = new Doku_Event($name, $data);
return $evt->trigger($action, $canPreventDefault);
}
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