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   1  <?php
   2  /**
   3   * The plugin API is located in this file, which allows for creating actions
   4   * and filters and hooking functions, and methods. The functions or methods will
   5   * then be run when the action or filter is called.
   6   *
   7   * The API callback examples reference functions, but can be methods of classes.
   8   * To hook methods, you'll need to pass an array one of two ways.
   9   *
  10   * Any of the syntaxes explained in the PHP documentation for the
  11   * {@link http://us2.php.net/manual/en/language.pseudo-types.php#language.types.callback 'callback'}
  12   * type are valid.
  13   *
  14   * Also see the {@link http://codex.wordpress.org/Plugin_API Plugin API} for more information
  15   * and examples on how to use a lot of these functions.
  16   *
  17   * @package WordPress
  18   * @subpackage Plugin
  19   * @since 1.5
  20   */
  21  
  22  /**
  23   * add_filter() - Hooks a function or method to a specific filter action.
  24   *
  25   * Filters are the hooks that WordPress launches to modify text of various types
  26   * before adding it to the database or sending it to the browser screen. Plugins
  27   * can specify that one or more of its PHP functions is executed to
  28   * modify specific types of text at these times, using the Filter API.
  29   *
  30   * To use the API, the following code should be used to bind a callback to the filter
  31   * <code>
  32   * function example_hook($example) { echo $example; }
  33   *
  34   * add_filter('example_filter', 'example_hook');
  35   * </code>
  36   *
  37   * In WordPress 1.5.1+, hooked functions can take extra arguments that are set when
  38   * the matching do_action() or apply_filters() call is run. The <tt>$accepted_args
  39   * allow for calling functions only when the number of args match. Hooked functions
  40   * can take extra arguments that are set when the matching <tt>do_action()</tt> or
  41   * <tt>apply_filters()</tt> call is run. For example, the action <tt>comment_id_not_found</tt>
  42   * will pass any functions that hook onto it the ID of the requested comment.
  43   *
  44   * <strong>Note:</strong> the function will return true no matter if the function was hooked
  45   * fails or not. There are no checks for whether the function exists beforehand and no checks
  46   * to whether the <tt>$function_to_add is even a string. It is up to you to take care and
  47   * this is done for optimization purposes, so everything is as quick as possible.
  48   *
  49   * @package WordPress
  50   * @subpackage Plugin
  51   * @since 0.71
  52   * @global array $wp_filter Stores all of the filters added in the form of
  53   *    wp_filter['tag']['array of priorities']['array of functions serialized']['array of ['array (functions, accepted_args)]']
  54   * @global array $merged_filters Tracks the tags that need to be merged for later. If the hook is added, it doesn't need to run through that process.
  55   *
  56   * @param string $tag The name of the filter to hook the <tt>$function_to_add</tt> to.
  57   * @param callback $function_to_add The name of the function to be called when the filter is applied.
  58   * @param int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
  59   * @param int $accepted_args optional. The number of arguments the function accept (default 1).
  60   * @return boolean true
  61   */
  62  function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
  63      global $wp_filter, $merged_filters;
  64  
  65      $idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority);
  66      $wp_filter[$tag][$priority][$idx] = array('function' => $function_to_add, 'accepted_args' => $accepted_args);
  67      unset( $merged_filters[ $tag ] );
  68      return true;
  69  }
  70  
  71  /**
  72   * has_filter() - Check if any filter has been registered for a hook.
  73   *
  74   * @package WordPress
  75   * @subpackage Plugin
  76   * @since 2.4
  77   * @global array $wp_filter Stores all of the filters
  78   *
  79   * @param string $tag The name of the filter hook.
  80   * @param callback $function_to_check optional.  If specified, return the priority of that function on this hook or false if not attached.
  81   * @return int|boolean Optionally returns the priority on that hook for the specified function.
  82   */
  83  function has_filter($tag, $function_to_check = false) {
  84      global $wp_filter;
  85  
  86      $has = !empty($wp_filter[$tag]);
  87      if ( false === $function_to_check || false == $has )
  88          return $has;
  89  
  90      if ( !$idx = _wp_filter_build_unique_id($tag, $function_to_check, false) )
  91          return false;
  92  
  93      foreach ( array_keys($wp_filter[$tag]) as $priority ) {
  94          if ( isset($wp_filter[$tag][$priority][$idx]) )
  95              return $priority;
  96      }
  97  
  98      return false;
  99  }
 100  
 101  /**
 102   * apply_filters() - Call the functions added to a filter hook.
 103   *
 104   * The callback functions attached to filter hook <tt>$tag</tt> are invoked by
 105   * calling this function. This function can be used to create a new filter hook
 106   * by simply calling this function with the name of the new hook specified using
 107   * the <tt>$tag</a> parameter.
 108   *
 109   * The function allows for additional arguments to be added and passed to hooks.
 110   * <code>
 111   * function example_hook($string, $arg1, $arg2)
 112   * {
 113   *        //Do stuff
 114   *        return $string;
 115   * }
 116   * $value = apply_filters('example_filter', 'filter me', 'arg1', 'arg2');
 117   * </code>
 118   *
 119   * @package WordPress
 120   * @subpackage Plugin
 121   * @since 0.71
 122   * @global array $wp_filter Stores all of the filters
 123   * @global array $merge_filters Merges the filter hooks using this function.
 124   * @global array $wp_current_filter stores the list of current filters with the current one last
 125   *
 126   * @param string $tag The name of the filter hook.
 127   * @param mixed $value The value on which the filters hooked to <tt>$tag</tt> are applied on.
 128   * @param mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>.
 129   * @return mixed The filtered value after all hooked functions are applied to it.
 130   */
 131  function apply_filters($tag, $value) {
 132      global $wp_filter, $merged_filters, $wp_current_filter;
 133  
 134      $args = array();
 135      $wp_current_filter[] = $tag;
 136  
 137      // Do 'all' actions first
 138      if ( isset($wp_filter['all']) ) {
 139          $args = func_get_args();
 140          _wp_call_all_hook($args);
 141      }
 142  
 143      if ( !isset($wp_filter[$tag]) ) {
 144          array_pop($wp_current_filter);
 145          return $value;
 146      }
 147  
 148      // Sort
 149      if ( !isset( $merged_filters[ $tag ] ) ) {
 150          ksort($wp_filter[$tag]);
 151          $merged_filters[ $tag ] = true;
 152      }
 153  
 154      reset( $wp_filter[ $tag ] );
 155  
 156      if ( empty($args) )
 157          $args = func_get_args();
 158  
 159      do {
 160          foreach( (array) current($wp_filter[$tag]) as $the_ )
 161              if ( !is_null($the_['function']) ){
 162                  $args[1] = $value;
 163                  $value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));
 164              }
 165  
 166      } while ( next($wp_filter[$tag]) !== false );
 167      
 168      array_pop( $wp_current_filter );
 169  
 170      return $value;
 171  }
 172  
 173  /**
 174   * remove_filter() - Removes a function from a specified filter hook.
 175   *
 176   * This function removes a function attached to a specified filter hook. This
 177   * method can be used to remove default functions attached to a specific filter
 178   * hook and possibly replace them with a substitute.
 179   *
 180   * To remove a hook, the <tt>$function_to_remove</tt> and <tt>$priority</tt> arguments
 181   * must match when the hook was added. This goes for both filters and actions. No warning
 182   * will be given on removal failure.
 183   *
 184   * @package WordPress
 185   * @subpackage Plugin
 186   * @since 1.2
 187   *
 188   * @param string $tag The filter hook to which the function to be removed is hooked.
 189   * @param callback $function_to_remove The name of the function which should be removed.
 190   * @param int $priority optional. The priority of the function (default: 10).
 191   * @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
 192   * @return boolean Whether the function existed before it was removed.
 193   */
 194  function remove_filter($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
 195      $function_to_remove = _wp_filter_build_unique_id($tag, $function_to_remove, $priority);
 196  
 197      $r = isset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
 198  
 199      if ( true === $r) {
 200          unset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
 201          if ( empty($GLOBALS['wp_filter'][$tag][$priority]) )
 202              unset($GLOBALS['wp_filter'][$tag][$priority]);
 203          unset($GLOBALS['merged_filters'][$tag]);
 204      }
 205  
 206      return $r;
 207  }
 208  
 209  
 210  /**
 211   * current_filter() - Return the name of the current filter or action.
 212   *
 213   * @package WordPress
 214   * @subpackage Plugin
 215   * @since 2.4
 216   *
 217   * @return string Hook name of the current filter or action.
 218   */
 219  function current_filter() {
 220      global $wp_current_filter;
 221      return end( $wp_current_filter );
 222  }
 223  
 224  
 225  /**
 226   * add_action() - Hooks a function on to a specific action.
 227   *
 228   * Actions are the hooks that the WordPress core launches at specific points
 229   * during execution, or when specific events occur. Plugins can specify that
 230   * one or more of its PHP functions are executed at these points, using the
 231   * Action API.
 232   *
 233   * @uses add_filter() Adds an action. Parameter list and functionality are the same.
 234   *
 235   * @package WordPress
 236   * @subpackage Plugin
 237   * @since 1.2
 238   *
 239   * @param string $tag The name of the action to which the <tt>$function_to-add</tt> is hooked.
 240   * @param callback $function_to_add The name of the function you wish to be called.
 241   * @param int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
 242   * @param int $accepted_args optional. The number of arguments the function accept (default 1).
 243   */
 244  function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
 245      return add_filter($tag, $function_to_add, $priority, $accepted_args);
 246  }
 247  
 248  
 249  /**
 250   * do_action() - Execute functions hooked on a specific action hook.
 251   *
 252   * This function invokes all functions attached to action hook <tt>$tag</tt>.
 253   * It is possible to create new action hooks by simply calling this function,
 254   * specifying the name of the new hook using the <tt>$tag</tt> parameter.
 255   *
 256   * You can pass extra arguments to the hooks, much like you can with apply_filters().
 257   *
 258   * @see apply_filters() This function works similar with the exception that nothing is
 259   * returned and only the functions or methods are called.
 260   *
 261   * @package WordPress
 262   * @subpackage Plugin
 263   * @since 1.2
 264   * @global array $wp_filter Stores all of the filters
 265   * @global array $wp_actions Increments the amount of times action was triggered.
 266   *
 267   * @param string $tag The name of the action to be executed.
 268   * @param mixed $arg,... Optional additional arguments which are passed on to the functions hooked to the action.
 269   * @return null Will return null if $tag does not exist in $wp_filter array
 270   */
 271  function do_action($tag, $arg = '') {
 272      global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
 273  
 274      if ( is_array($wp_actions) )
 275          $wp_actions[] = $tag;
 276      else
 277          $wp_actions = array($tag);
 278  
 279      $wp_current_filter[] = $tag;
 280  
 281      // Do 'all' actions first
 282      if ( isset($wp_filter['all']) ) {
 283          $all_args = func_get_args();
 284          _wp_call_all_hook($all_args);
 285      }
 286  
 287      if ( !isset($wp_filter[$tag]) ) {
 288          array_pop($wp_current_filter);
 289          return;
 290      }
 291  
 292      $args = array();
 293      if ( is_array($arg) && 1 == count($arg) && is_object($arg[0]) ) // array(&$this)
 294          $args[] =& $arg[0];
 295      else
 296          $args[] = $arg;
 297      for ( $a = 2; $a < func_num_args(); $a++ )
 298          $args[] = func_get_arg($a);
 299  
 300      // Sort
 301      if ( !isset( $merged_filters[ $tag ] ) ) {
 302          ksort($wp_filter[$tag]);
 303          $merged_filters[ $tag ] = true;
 304      }
 305  
 306      reset( $wp_filter[ $tag ] );
 307  
 308      do {
 309          foreach ( (array) current($wp_filter[$tag]) as $the_ )
 310              if ( !is_null($the_['function']) )
 311                  call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 312  
 313      } while ( next($wp_filter[$tag]) !== false );
 314  
 315      array_pop($wp_current_filter);
 316  }
 317  
 318  /**
 319   * did_action() - Return the number times an action is fired.
 320   *
 321   * @package WordPress
 322   * @subpackage Plugin
 323   * @since 2.1
 324   * @global array $wp_actions Increments the amount of times action was triggered.
 325   *
 326   * @param string $tag The name of the action hook.
 327   * @return int The number of times action hook <tt>$tag</tt> is fired
 328   */
 329  function did_action($tag) {
 330      global $wp_actions;
 331  
 332      if ( empty($wp_actions) )
 333          return 0;
 334  
 335      return count(array_keys($wp_actions, $tag));
 336  }
 337  
 338  /**
 339   * do_action_ref_array() - Execute functions hooked on a specific action hook, specifying arguments in an array.
 340   *
 341   * @see do_action() This function is identical, but the arguments passed to
 342   * the functions hooked to <tt>$tag</tt> are supplied using an array.
 343   *
 344   * @package WordPress
 345   * @subpackage Plugin
 346   * @since 2.1
 347   * @global array $wp_filter Stores all of the filters
 348   * @global array $wp_actions Increments the amount of times action was triggered.
 349   *
 350   * @param string $tag The name of the action to be executed.
 351   * @param array $args The arguments supplied to the functions hooked to <tt>$tag</tt>
 352   * @return null Will return null if $tag does not exist in $wp_filter array
 353   */
 354  function do_action_ref_array($tag, $args) {
 355      global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
 356  
 357      if ( !is_array($wp_actions) )
 358          $wp_actions = array($tag);
 359      else
 360          $wp_actions[] = $tag;
 361  
 362      $wp_current_filter[] = $tag;
 363  
 364      // Do 'all' actions first
 365      if ( isset($wp_filter['all']) ) {
 366          $all_args = func_get_args();
 367          _wp_call_all_hook($all_args);
 368      }
 369  
 370      if ( !isset($wp_filter[$tag]) ) {
 371          array_pop($wp_current_filter);
 372          return;
 373      }
 374  
 375      // Sort
 376      if ( !isset( $merged_filters[ $tag ] ) ) {
 377          ksort($wp_filter[$tag]);
 378          $merged_filters[ $tag ] = true;
 379      }
 380  
 381      reset( $wp_filter[ $tag ] );
 382  
 383      do {
 384          foreach( (array) current($wp_filter[$tag]) as $the_ )
 385              if ( !is_null($the_['function']) )
 386                  call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 387  
 388      } while ( next($wp_filter[$tag]) !== false );
 389  
 390      array_pop($wp_current_filter);
 391  }
 392  
 393  /**
 394   * has_action() - Check if any action has been registered for a hook.
 395   *
 396   * @package WordPress
 397   * @subpackage Plugin
 398   * @since 2.4
 399   * @see has_filter() has_action() is an alias of has_filter().
 400   *
 401   * @param string $tag The name of the action hook.
 402   * @param callback $function_to_check optional.  If specified, return the priority of that function on this hook or false if not attached.
 403   * @return int|boolean Optionally returns the priority on that hook for the specified function.
 404   */
 405  function has_action($tag, $function_to_check = false) {
 406      return has_filter($tag, $function_to_check);
 407  }
 408  
 409  /**
 410   * remove_action() - Removes a function from a specified action hook.
 411   *
 412   * This function removes a function attached to a specified action hook. This
 413   * method can be used to remove default functions attached to a specific filter
 414   * hook and possibly replace them with a substitute.
 415   *
 416   * @package WordPress
 417   * @subpackage Plugin
 418   * @since 1.2
 419   *
 420   * @param string $tag The action hook to which the function to be removed is hooked.
 421   * @param callback $function_to_remove The name of the function which should be removed.
 422   * @param int $priority optional The priority of the function (default: 10).
 423   * @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
 424   * @return boolean Whether the function is removed.
 425   */
 426  function remove_action($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
 427      return remove_filter($tag, $function_to_remove, $priority, $accepted_args);
 428  }
 429  
 430  //
 431  // Functions for handling plugins.
 432  //
 433  
 434  /**
 435   * plugin_basename() - Gets the basename of a plugin.
 436   *
 437   * This method extract the name of a plugin from its filename.
 438   *
 439   * @package WordPress
 440   * @subpackage Plugin
 441   * @since 1.5
 442   *
 443   * @access private
 444   *
 445   * @param string $file The filename of plugin.
 446   * @return string The name of a plugin.
 447   */
 448  function plugin_basename($file) {
 449      $file = str_replace('\\','/',$file); // sanitize for Win32 installs
 450      $file = preg_replace('|/+|','/', $file); // remove any duplicate slash
 451      $file = preg_replace('|^.*/wp-content/plugins/|','',$file); // get relative path from plugins dir
 452      return $file;
 453  }
 454  
 455  /**
 456   * register_activation_hook() - Hook a function on a plugin activation action hook.
 457   *
 458   * When a plugin is activated, the action 'activate_PLUGINNAME' hook is
 459   * activated. In the name of this hook, PLUGINNAME is replaced with the name of
 460   * the plugin, including the optional subdirectory. For example, when the plugin
 461   * is located in <tt>wp-content/plugin/sampleplugin/sample.php</tt>, then the
 462   * name of this hook will become 'activate_sampleplugin/sample.php'
 463   * When the plugin consists of only one file and is (as by default) located at
 464   * <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
 465   * 'activate_sample.php'.
 466   *
 467   * @package WordPress
 468   * @subpackage Plugin
 469   * @since 2.0
 470   *
 471   * @access private
 472   *
 473   * @param string $file The filename of the plugin including the path.
 474   * @param string $function the function hooked to the 'activate_PLUGIN' action.
 475   */
 476  function register_activation_hook($file, $function) {
 477      $file = plugin_basename($file);
 478      add_action('activate_' . $file, $function);
 479  }
 480  
 481  /**
 482   * register_deactivation_hook() - Hook a function on a plugin deactivation action hook.
 483   *
 484   * When a plugin is deactivated, the action 'deactivate_PLUGINNAME' hook is
 485   * deactivated. In the name of this hook, PLUGINNAME is replaced with the name of
 486   * the plugin, including the optional subdirectory. For example, when the plugin
 487   * is located in <tt>wp-content/plugin/sampleplugin/sample.php</tt>, then the
 488   * name of this hook will become 'activate_sampleplugin/sample.php'.
 489   * When the plugin consists of only one file and is (as by default) located at
 490   * <tt>wp-content/plugin/sample.php</tt> the name of this hook will be
 491   * 'activate_sample.php'.
 492   *
 493   * @package WordPress
 494   * @subpackage Plugin
 495   * @since 2.0
 496   *
 497   * @access private
 498   *
 499   * @param string $file The filename of the plugin including the path.
 500   * @param string $function the function hooked to the 'activate_PLUGIN' action.
 501   */
 502  function register_deactivation_hook($file, $function) {
 503      $file = plugin_basename($file);
 504      add_action('deactivate_' . $file, $function);
 505  }
 506  
 507  /** 
 508   * _wp_call_all_hook() - Calls the 'all' hook, which will process the functions hooked into it.
 509   *
 510   * The 'all' hook passes all of the arguments or parameters that were used for the
 511   * hook, which this function was called for. The first parameter will have to be tested
 512   * as it will be the hook name.
 513   *
 514   * This function is used internally for apply_filters(), do_action(), and do_action_ref_array()
 515   * and is not meant to be used from outside those functions. This function does not check for the
 516   * existent of the all hook, so it will fail unless the all hook exists prior to this function call.
 517   *
 518   * @package WordPress
 519   * @subpackage Plugin
 520   * @since 2.4
 521   * @access private
 522   *
 523   * @uses $wp_filter Used to process all of the functions in the 'all' hook
 524   *
 525   * @param array $args The collected parameters from the hook that was called.
 526   * @param string $hook Optional. The hook name that was used to call the 'all' hook.
 527   */ 
 528  function _wp_call_all_hook($args) { 
 529      global $wp_filter; 
 530  
 531      reset( $wp_filter['all'] );
 532      do {
 533          foreach( (array) current($wp_filter['all']) as $the_ )
 534              if ( !is_null($the_['function']) )
 535                  call_user_func_array($the_['function'], $args);
 536  
 537      } while ( next($wp_filter['all']) !== false );
 538  }
 539  
 540  /**
 541   * _wp_filter_build_unique_id() - Build Unique ID for storage and retrieval
 542   *
 543   * The old way to serialize the callback caused issues and this function is the
 544   * solution. It works by checking for objects and creating an a new property in
 545   * the class to keep track of the object and new objects of the same class that
 546   * need to be added.
 547   *
 548   * It also allows for the removal of actions and filters for objects after they
 549   * change class properties. It is possible to include the property $wp_filter_id
 550   * in your class and set it to "null" or a number to bypass the workaround. However
 551   * this will prevent you from adding new classes and any new classes will overwrite
 552   * the previous hook by the same class.
 553   *
 554   * Functions and static method callbacks are just returned as strings and shouldn't
 555   * have any speed penalty.
 556   *
 557   * @package WordPress
 558   * @subpackage Plugin
 559   * @since 2.2.3
 560   *
 561   * @link http://trac.wordpress.org/ticket/3875
 562   *
 563   * @access private
 564   *
 565   * @global array $wp_filter Storage for all of the filters and actions
 566   * @param string $tag Used in counting how many hooks were applied
 567   * @param string|array $function Used for creating unique id
 568   * @param int|bool $priority Used in counting how many hooks were applied.  If === false and $function is an object reference, we return the unique id only if it already has one, false otherwise.
 569   * @param string $type filter or action
 570   * @return string Unique ID for usage as array key
 571   */
 572  function _wp_filter_build_unique_id($tag, $function, $priority) {
 573      global $wp_filter;
 574  
 575      // If function then just skip all of the tests and not overwrite the following.
 576      if ( is_string($function) )
 577          return $function;
 578      // Object Class Calling
 579      else if (is_object($function[0]) ) {
 580          $obj_idx = get_class($function[0]).$function[1];
 581          if ( !isset($function[0]->wp_filter_id) ) {
 582              if ( false === $priority )
 583                  return false;
 584              $count = count((array)$wp_filter[$tag][$priority]);
 585              $function[0]->wp_filter_id = $count;
 586              $obj_idx .= $count;
 587              unset($count);
 588          } else
 589              $obj_idx .= $function[0]->wp_filter_id;
 590          return $obj_idx;
 591      }
 592      // Static Calling
 593      else if ( is_string($function[0]) )
 594          return $function[0].$function[1];
 595  }
 596  
 597  ?>