1 | <?php
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2 | /**
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3 | * DokuWiki Events
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4 | *
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5 | * @license GPL 2 (http://www.gnu.org/licenses/gpl.html)
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6 | * @author Christopher Smith <[email protected]>
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7 | */
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8 |
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9 | if(!defined('DOKU_INC')) die('meh.');
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10 |
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11 | class Doku_Event {
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12 |
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13 | // public properties
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14 | var $name = ''; // READONLY event name, objects must register against this name to see the event
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15 | var $data = null; // READWRITE data relevant to the event, no standardised format (YET!)
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16 | var $result = null; // READWRITE the results of the event action, only relevant in "_AFTER" advise
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17 | // event handlers may modify this if they are preventing the default action
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18 | // to provide the after event handlers with event results
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19 | var $canPreventDefault = true; // READONLY if true, event handlers can prevent the events default action
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20 |
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21 | // private properties, event handlers can effect these through the provided methods
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22 | var $_default = true; // whether or not to carry out the default action associated with the event
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23 | var $_continue = true; // whether or not to continue propagating the event to other handlers
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24 |
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25 | /**
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26 | * event constructor
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27 | */
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28 | function Doku_Event($name, &$data) {
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29 |
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30 | $this->name = $name;
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31 | $this->data =& $data;
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32 |
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33 | }
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34 |
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35 | /**
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36 | * advise functions
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37 | *
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38 | * advise all registered handlers of this event
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39 | *
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40 | * if these methods are used by functions outside of this object, they must
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41 | * properly handle correct processing of any default action and issue an
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42 | * advise_after() signal. e.g.
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43 | * $evt = new Doku_Event(name, data);
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44 | * if ($evt->advise_before(canPreventDefault) {
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45 | * // default action code block
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46 | * }
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47 | * $evt->advise_after();
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48 | * unset($evt);
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49 | *
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50 | * @return results of processing the event, usually $this->_default
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51 | */
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52 | function advise_before($enablePreventDefault=true) {
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53 | global $EVENT_HANDLER;
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54 |
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55 | $this->canPreventDefault = $enablePreventDefault;
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56 | $EVENT_HANDLER->process_event($this,'BEFORE');
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57 |
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58 | return (!$enablePreventDefault || $this->_default);
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59 | }
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60 |
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61 | function advise_after() {
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62 | global $EVENT_HANDLER;
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63 |
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64 | $this->_continue = true;
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65 | $EVENT_HANDLER->process_event($this,'AFTER');
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66 | }
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67 |
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68 | /**
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69 | * trigger
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70 | *
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71 | * - advise all registered (<event>_BEFORE) handlers that this event is about to take place
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72 | * - carry out the default action using $this->data based on $enablePrevent and
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73 | * $this->_default, all of which may have been modified by the event handlers.
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74 | * - advise all registered (<event>_AFTER) handlers that the event has taken place
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75 | *
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76 | * @return $event->results
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77 | * the value set by any <event>_before or <event> handlers if the default action is prevented
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78 | * or the results of the default action (as modified by <event>_after handlers)
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79 | * or NULL no action took place and no handler modified the value
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80 | */
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81 | function trigger($action=null, $enablePrevent=true) {
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82 |
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83 | if (!is_callable($action)) $enablePrevent = false;
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84 |
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85 | if ($this->advise_before($enablePrevent) && is_callable($action)) {
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86 | if (is_array($action)) {
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87 | list($obj,$method) = $action;
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88 | $this->result = $obj->$method($this->data);
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89 | } else {
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90 | $this->result = $action($this->data);
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91 | }
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92 | }
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93 |
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94 | $this->advise_after();
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95 |
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96 | return $this->result;
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97 | }
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98 |
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99 | /**
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100 | * stopPropagation
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101 | *
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102 | * stop any further processing of the event by event handlers
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103 | * this function does not prevent the default action taking place
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104 | */
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105 | function stopPropagation() { $this->_continue = false; }
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106 |
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107 | /**
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108 | * preventDefault
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109 | *
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110 | * prevent the default action taking place
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111 | */
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112 | function preventDefault() { $this->_default = false; }
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113 | }
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114 |
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115 | class Doku_Event_Handler {
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116 |
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117 | // public properties: none
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118 |
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119 | // private properties
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120 | var $_hooks = array(); // array of events and their registered handlers
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121 |
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122 | /**
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123 | * event_handler
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124 | *
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125 | * constructor, loads all action plugins and calls their register() method giving them
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126 | * an opportunity to register any hooks they require
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127 | */
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128 | function Doku_Event_Handler() {
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129 |
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130 | // load action plugins
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131 | $plugin = null;
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132 | $pluginlist = plugin_list('action');
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133 |
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134 | foreach ($pluginlist as $plugin_name) {
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135 | $plugin =& plugin_load('action',$plugin_name);
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136 |
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137 | if ($plugin !== null) $plugin->register($this);
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138 | }
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139 | }
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140 |
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141 | /**
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142 | * register_hook
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143 | *
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144 | * register a hook for an event
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145 | *
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146 | * @param $event (string) name used by the event, (incl '_before' or '_after' for triggers)
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147 | * @param $obj (obj) object in whose scope method is to be executed,
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148 | * if NULL, method is assumed to be a globally available function
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149 | * @param $method (function) event handler function
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150 | * @param $param (mixed) data passed to the event handler
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151 | */
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152 | function register_hook($event, $advise, &$obj, $method, $param=null) {
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153 | $this->_hooks[$event.'_'.$advise][] = array(&$obj, $method, $param);
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154 | }
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155 |
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156 | function process_event(&$event,$advise='') {
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157 |
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158 | $evt_name = $event->name . ($advise ? '_'.$advise : '_BEFORE');
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159 |
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160 | if (!empty($this->_hooks[$evt_name])) {
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161 | $hook = reset($this->_hooks[$evt_name]);
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162 | do {
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163 | // list($obj, $method, $param) = $hook;
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164 | $obj =& $hook[0];
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165 | $method = $hook[1];
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166 | $param = $hook[2];
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167 |
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168 | if (is_null($obj)) {
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169 | $method($event, $param);
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170 | } else {
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171 | $obj->$method($event, $param);
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172 | }
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173 |
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174 | } while ($event->_continue && $hook = next($this->_hooks[$evt_name]));
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175 | }
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176 | }
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177 | }
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178 |
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179 | /**
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180 | * trigger_event
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181 | *
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182 | * function wrapper to process (create, trigger and destroy) an event
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183 | *
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184 | * @param $name (string) name for the event
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185 | * @param $data (mixed) event data
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186 | * @param $action (callback) (optional, default=NULL) default action, a php callback function
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187 | * @param $canPreventDefault (bool) (optional, default=true) can hooks prevent the default action
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188 | *
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189 | * @return (mixed) the event results value after all event processing is complete
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190 | * by default this is the return value of the default action however
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191 | * it can be set or modified by event handler hooks
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192 | */
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193 | function trigger_event($name, &$data, $action=null, $canPreventDefault=true) {
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194 |
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195 | $evt = new Doku_Event($name, $data);
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196 | return $evt->trigger($action, $canPreventDefault);
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197 | }
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