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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
  15   * more information 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   * 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
  31   * filter.
  32   *
  33   * <code>
  34   * function example_hook($example) { echo $example; }
  35   * add_filter('example_filter', 'example_hook');
  36   * </code>
  37   *
  38   * In WordPress 1.5.1+, hooked functions can take extra arguments that are set
  39   * when the matching do_action() or apply_filters() call is run. The
  40   * $accepted_args allow for calling functions only when the number of args
  41   * match. Hooked functions can take extra arguments that are set when the
  42   * matching do_action() or apply_filters() call is run. For example, the action
  43   * comment_id_not_found will pass any functions that hook onto it the ID of the
  44   * requested comment.
  45   *
  46   * <strong>Note:</strong> the function will return true no matter if the
  47   * function was hooked fails or not. There are no checks for whether the
  48   * function exists beforehand and no checks to whether the <tt>$function_to_add
  49   * is even a string. It is up to you to take care and this is done for
  50   * optimization purposes, so everything is as quick as possible.
  51   *
  52   * @package WordPress
  53   * @subpackage Plugin
  54   * @since 0.71
  55   * @global array $wp_filter Stores all of the filters added in the form of
  56   *    wp_filter['tag']['array of priorities']['array of functions serialized']['array of ['array (functions, accepted_args)]']
  57   * @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.
  58   *
  59   * @param string $tag The name of the filter to hook the $function_to_add to.
  60   * @param callback $function_to_add The name of the function to be called when the filter is applied.
  61   * @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.
  62   * @param int $accepted_args optional. The number of arguments the function accept (default 1).
  63   * @return boolean true
  64   */
  65  function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
  66      global $wp_filter, $merged_filters;
  67  
  68      $idx = _wp_filter_build_unique_id($tag, $function_to_add, $priority);
  69      $wp_filter[$tag][$priority][$idx] = array('function' => $function_to_add, 'accepted_args' => $accepted_args);
  70      unset( $merged_filters[ $tag ] );
  71      return true;
  72  }
  73  
  74  /**
  75   * Check if any filter has been registered for a hook.
  76   *
  77   * @package WordPress
  78   * @subpackage Plugin
  79   * @since 2.5
  80   * @global array $wp_filter Stores all of the filters
  81   *
  82   * @param string $tag The name of the filter hook.
  83   * @param callback $function_to_check optional.  If specified, return the priority of that function on this hook or false if not attached.
  84   * @return int|boolean Optionally returns the priority on that hook for the specified function.
  85   */
  86  function has_filter($tag, $function_to_check = false) {
  87      global $wp_filter;
  88  
  89      $has = !empty($wp_filter[$tag]);
  90      if ( false === $function_to_check || false == $has )
  91          return $has;
  92  
  93      if ( !$idx = _wp_filter_build_unique_id($tag, $function_to_check, false) )
  94          return false;
  95  
  96      foreach ( (array) array_keys($wp_filter[$tag]) as $priority ) {
  97          if ( isset($wp_filter[$tag][$priority][$idx]) )
  98              return $priority;
  99      }
 100  
 101      return false;
 102  }
 103  
 104  /**
 105   * Call the functions added to a filter hook.
 106   *
 107   * The callback functions attached to filter hook $tag are invoked by calling
 108   * this function. This function can be used to create a new filter hook by
 109   * simply calling this function with the name of the new hook specified using
 110   * the $tag parameter.
 111   *
 112   * The function allows for additional arguments to be added and passed to hooks.
 113   * <code>
 114   * function example_hook($string, $arg1, $arg2)
 115   * {
 116   *        //Do stuff
 117   *        return $string;
 118   * }
 119   * $value = apply_filters('example_filter', 'filter me', 'arg1', 'arg2');
 120   * </code>
 121   *
 122   * @package WordPress
 123   * @subpackage Plugin
 124   * @since 0.71
 125   * @global array $wp_filter Stores all of the filters
 126   * @global array $merged_filters Merges the filter hooks using this function.
 127   * @global array $wp_current_filter stores the list of current filters with the current one last
 128   *
 129   * @param string $tag The name of the filter hook.
 130   * @param mixed $value The value on which the filters hooked to <tt>$tag</tt> are applied on.
 131   * @param mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>.
 132   * @return mixed The filtered value after all hooked functions are applied to it.
 133   */
 134  function apply_filters($tag, $value) {
 135      global $wp_filter, $merged_filters, $wp_current_filter;
 136  
 137      $args = array();
 138      $wp_current_filter[] = $tag;
 139  
 140      // Do 'all' actions first
 141      if ( isset($wp_filter['all']) ) {
 142          $args = func_get_args();
 143          _wp_call_all_hook($args);
 144      }
 145  
 146      if ( !isset($wp_filter[$tag]) ) {
 147          array_pop($wp_current_filter);
 148          return $value;
 149      }
 150  
 151      // Sort
 152      if ( !isset( $merged_filters[ $tag ] ) ) {
 153          ksort($wp_filter[$tag]);
 154          $merged_filters[ $tag ] = true;
 155      }
 156  
 157      reset( $wp_filter[ $tag ] );
 158  
 159      if ( empty($args) )
 160          $args = func_get_args();
 161  
 162      do {
 163          foreach( (array) current($wp_filter[$tag]) as $the_ )
 164              if ( !is_null($the_['function']) ){
 165                  $args[1] = $value;
 166                  $value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));
 167              }
 168  
 169      } while ( next($wp_filter[$tag]) !== false );
 170  
 171      array_pop( $wp_current_filter );
 172  
 173      return $value;
 174  }
 175  
 176  /**
 177   * Removes a function from a specified filter hook.
 178   *
 179   * This function removes a function attached to a specified filter hook. This
 180   * method can be used to remove default functions attached to a specific filter
 181   * hook and possibly replace them with a substitute.
 182   *
 183   * To remove a hook, the $function_to_remove and $priority arguments must match
 184   * when the hook was added. This goes for both filters and actions. No warning
 185   * will be given on removal failure.
 186   *
 187   * @package WordPress
 188   * @subpackage Plugin
 189   * @since 1.2
 190   *
 191   * @param string $tag The filter hook to which the function to be removed is hooked.
 192   * @param callback $function_to_remove The name of the function which should be removed.
 193   * @param int $priority optional. The priority of the function (default: 10).
 194   * @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
 195   * @return boolean Whether the function existed before it was removed.
 196   */
 197  function remove_filter($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
 198      $function_to_remove = _wp_filter_build_unique_id($tag, $function_to_remove, $priority);
 199  
 200      $r = isset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
 201  
 202      if ( true === $r) {
 203          unset($GLOBALS['wp_filter'][$tag][$priority][$function_to_remove]);
 204          if ( empty($GLOBALS['wp_filter'][$tag][$priority]) )
 205              unset($GLOBALS['wp_filter'][$tag][$priority]);
 206          unset($GLOBALS['merged_filters'][$tag]);
 207      }
 208  
 209      return $r;
 210  }
 211  
 212  /**
 213   * Remove all of the hooks from a filter.
 214   *
 215   * @since 2.7
 216   *
 217   * @param string $tag The filter to remove hooks from.
 218   * @param int $priority The priority number to remove.
 219   * @return bool True when finished.
 220   */
 221  function remove_all_filters($tag, $priority = false) {
 222      global $wp_filter, $merged_filters;
 223  
 224      if( isset($wp_filter[$tag]) ) {
 225          if( false !== $priority && isset($$wp_filter[$tag][$priority]) )
 226              unset($wp_filter[$tag][$priority]);
 227          else
 228              unset($wp_filter[$tag]);
 229      }
 230  
 231      if( isset($merged_filters[$tag]) )
 232          unset($merged_filters[$tag]);
 233  
 234      return true;
 235  }
 236  
 237  /**
 238   * Retrieve the name of the current filter or action.
 239   *
 240   * @package WordPress
 241   * @subpackage Plugin
 242   * @since 2.5
 243   *
 244   * @return string Hook name of the current filter or action.
 245   */
 246  function current_filter() {
 247      global $wp_current_filter;
 248      return end( $wp_current_filter );
 249  }
 250  
 251  
 252  /**
 253   * Hooks a function on to a specific action.
 254   *
 255   * Actions are the hooks that the WordPress core launches at specific points
 256   * during execution, or when specific events occur. Plugins can specify that
 257   * one or more of its PHP functions are executed at these points, using the
 258   * Action API.
 259   *
 260   * @uses add_filter() Adds an action. Parameter list and functionality are the same.
 261   *
 262   * @package WordPress
 263   * @subpackage Plugin
 264   * @since 1.2
 265   *
 266   * @param string $tag The name of the action to which the $function_to_add is hooked.
 267   * @param callback $function_to_add The name of the function you wish to be called.
 268   * @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.
 269   * @param int $accepted_args optional. The number of arguments the function accept (default 1).
 270   */
 271  function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
 272      return add_filter($tag, $function_to_add, $priority, $accepted_args);
 273  }
 274  
 275  
 276  /**
 277   * Execute functions hooked on a specific action hook.
 278   *
 279   * This function invokes all functions attached to action hook $tag. It is
 280   * possible to create new action hooks by simply calling this function,
 281   * specifying the name of the new hook using the <tt>$tag</tt> parameter.
 282   *
 283   * You can pass extra arguments to the hooks, much like you can with
 284   * apply_filters().
 285   *
 286   * @see apply_filters() This function works similar with the exception that
 287   * nothing is returned and only the functions or methods are called.
 288   *
 289   * @package WordPress
 290   * @subpackage Plugin
 291   * @since 1.2
 292   * @global array $wp_filter Stores all of the filters
 293   * @global array $wp_actions Increments the amount of times action was triggered.
 294   *
 295   * @param string $tag The name of the action to be executed.
 296   * @param mixed $arg,... Optional additional arguments which are passed on to the functions hooked to the action.
 297   * @return null Will return null if $tag does not exist in $wp_filter array
 298   */
 299  function do_action($tag, $arg = '') {
 300      global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
 301  
 302      if ( is_array($wp_actions) )
 303          $wp_actions[] = $tag;
 304      else
 305          $wp_actions = array($tag);
 306  
 307      $wp_current_filter[] = $tag;
 308  
 309      // Do 'all' actions first
 310      if ( isset($wp_filter['all']) ) {
 311          $all_args = func_get_args();
 312          _wp_call_all_hook($all_args);
 313      }
 314  
 315      if ( !isset($wp_filter[$tag]) ) {
 316          array_pop($wp_current_filter);
 317          return;
 318      }
 319  
 320      $args = array();
 321      if ( is_array($arg) && 1 == count($arg) && is_object($arg[0]) ) // array(&$this)
 322          $args[] =& $arg[0];
 323      else
 324          $args[] = $arg;
 325      for ( $a = 2; $a < func_num_args(); $a++ )
 326          $args[] = func_get_arg($a);
 327  
 328      // Sort
 329      if ( !isset( $merged_filters[ $tag ] ) ) {
 330          ksort($wp_filter[$tag]);
 331          $merged_filters[ $tag ] = true;
 332      }
 333  
 334      reset( $wp_filter[ $tag ] );
 335  
 336      do {
 337          foreach ( (array) current($wp_filter[$tag]) as $the_ )
 338              if ( !is_null($the_['function']) )
 339                  call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 340  
 341      } while ( next($wp_filter[$tag]) !== false );
 342  
 343      array_pop($wp_current_filter);
 344  }
 345  
 346  /**
 347   * Retrieve the number times an action is fired.
 348   *
 349   * @package WordPress
 350   * @subpackage Plugin
 351   * @since 2.1
 352   * @global array $wp_actions Increments the amount of times action was triggered.
 353   *
 354   * @param string $tag The name of the action hook.
 355   * @return int The number of times action hook <tt>$tag</tt> is fired
 356   */
 357  function did_action($tag) {
 358      global $wp_actions;
 359  
 360      if ( empty($wp_actions) )
 361          return 0;
 362  
 363      return count(array_keys($wp_actions, $tag));
 364  }
 365  
 366  /**
 367   * Execute functions hooked on a specific action hook, specifying arguments in an array.
 368   *
 369   * @see do_action() This function is identical, but the arguments passed to the
 370   * functions hooked to <tt>$tag</tt> are supplied using an array.
 371   *
 372   * @package WordPress
 373   * @subpackage Plugin
 374   * @since 2.1
 375   * @global array $wp_filter Stores all of the filters
 376   * @global array $wp_actions Increments the amount of times action was triggered.
 377   *
 378   * @param string $tag The name of the action to be executed.
 379   * @param array $args The arguments supplied to the functions hooked to <tt>$tag</tt>
 380   * @return null Will return null if $tag does not exist in $wp_filter array
 381   */
 382  function do_action_ref_array($tag, $args) {
 383      global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
 384  
 385      if ( !is_array($wp_actions) )
 386          $wp_actions = array($tag);
 387      else
 388          $wp_actions[] = $tag;
 389  
 390      $wp_current_filter[] = $tag;
 391  
 392      // Do 'all' actions first
 393      if ( isset($wp_filter['all']) ) {
 394          $all_args = func_get_args();
 395          _wp_call_all_hook($all_args);
 396      }
 397  
 398      if ( !isset($wp_filter[$tag]) ) {
 399          array_pop($wp_current_filter);
 400          return;
 401      }
 402  
 403      // Sort
 404      if ( !isset( $merged_filters[ $tag ] ) ) {
 405          ksort($wp_filter[$tag]);
 406          $merged_filters[ $tag ] = true;
 407      }
 408  
 409      reset( $wp_filter[ $tag ] );
 410  
 411      do {
 412          foreach( (array) current($wp_filter[$tag]) as $the_ )
 413              if ( !is_null($the_['function']) )
 414                  call_user_func_array($the_['function'], array_slice($args, 0, (int) $the_['accepted_args']));
 415  
 416      } while ( next($wp_filter[$tag]) !== false );
 417  
 418      array_pop($wp_current_filter);
 419  }
 420  
 421  /**
 422   * Check if any action has been registered for a hook.
 423   *
 424   * @package WordPress
 425   * @subpackage Plugin
 426   * @since 2.5
 427   * @see has_filter() has_action() is an alias of has_filter().
 428   *
 429   * @param string $tag The name of the action hook.
 430   * @param callback $function_to_check optional.  If specified, return the priority of that function on this hook or false if not attached.
 431   * @return int|boolean Optionally returns the priority on that hook for the specified function.
 432   */
 433  function has_action($tag, $function_to_check = false) {
 434      return has_filter($tag, $function_to_check);
 435  }
 436  
 437  /**
 438   * Removes a function from a specified action hook.
 439   *
 440   * This function removes a function attached to a specified action hook. This
 441   * method can be used to remove default functions attached to a specific filter
 442   * hook and possibly replace them with a substitute.
 443   *
 444   * @package WordPress
 445   * @subpackage Plugin
 446   * @since 1.2
 447   *
 448   * @param string $tag The action hook to which the function to be removed is hooked.
 449   * @param callback $function_to_remove The name of the function which should be removed.
 450   * @param int $priority optional The priority of the function (default: 10).
 451   * @param int $accepted_args optional. The number of arguments the function accpets (default: 1).
 452   * @return boolean Whether the function is removed.
 453   */
 454  function remove_action($tag, $function_to_remove, $priority = 10, $accepted_args = 1) {
 455      return remove_filter($tag, $function_to_remove, $priority, $accepted_args);
 456  }
 457  
 458  /**
 459   * Remove all of the hooks from an action.
 460   *
 461   * @since 2.7
 462   *
 463   * @param string $tag The action to remove hooks from.
 464   * @param int $priority The priority number to remove them from.
 465   * @return bool True when finished.
 466   */
 467  function remove_all_actions($tag, $priority = false) {
 468      return remove_all_filters($tag, $priority);
 469  }
 470  
 471  //
 472  // Functions for handling plugins.
 473  //
 474  
 475  /**
 476   * Gets the basename of a plugin.
 477   *
 478   * This method extracts the name of a plugin from its filename.
 479   *
 480   * @package WordPress
 481   * @subpackage Plugin
 482   * @since 1.5
 483   *
 484   * @access private
 485   *
 486   * @param string $file The filename of plugin.
 487   * @return string The name of a plugin.
 488   * @uses WP_PLUGIN_DIR
 489   */
 490  function plugin_basename($file) {
 491      $file = str_replace('\\','/',$file); // sanitize for Win32 installs
 492      $file = preg_replace('|/+|','/', $file); // remove any duplicate slash
 493      $plugin_dir = str_replace('\\','/',WP_PLUGIN_DIR); // sanitize for Win32 installs
 494      $plugin_dir = preg_replace('|/+|','/', $plugin_dir); // remove any duplicate slash
 495      $file = preg_replace('|^' . preg_quote($plugin_dir, '|') . '/|','',$file); // get relative path from plugins dir
 496      return $file;
 497  }
 498  
 499  /**
 500   * Set the activation hook for a plugin.
 501   *
 502   * When a plugin is activated, the action 'activate_PLUGINNAME' hook is
 503   * activated. In the name of this hook, PLUGINNAME is replaced with the name of
 504   * the plugin, including the optional subdirectory. For example, when the plugin
 505   * is located in wp-content/plugin/sampleplugin/sample.php, then the name of
 506   * this hook will become 'activate_sampleplugin/sample.php'. When the plugin
 507   * consists of only one file and is (as by default) located at
 508   * wp-content/plugin/sample.php the name of this hook will be
 509   * 'activate_sample.php'.
 510   *
 511   * @package WordPress
 512   * @subpackage Plugin
 513   * @since 2.0
 514   *
 515   * @access private
 516   *
 517   * @param string $file The filename of the plugin including the path.
 518   * @param callback $function the function hooked to the 'activate_PLUGIN' action.
 519   */
 520  function register_activation_hook($file, $function) {
 521      $file = plugin_basename($file);
 522      add_action('activate_' . $file, $function);
 523  }
 524  
 525  /**
 526   * Set the deactivation hook for a plugin.
 527   *
 528   * When a plugin is deactivated, the action 'deactivate_PLUGINNAME' hook is
 529   * deactivated. In the name of this hook, PLUGINNAME is replaced with the name
 530   * of the plugin, including the optional subdirectory. For example, when the
 531   * plugin is located in wp-content/plugin/sampleplugin/sample.php, then
 532   * the name of this hook will become 'activate_sampleplugin/sample.php'.
 533   *
 534   * When the plugin consists of only one file and is (as by default) located at
 535   * wp-content/plugin/sample.php the name of this hook will be
 536   * 'activate_sample.php'.
 537   *
 538   * @package WordPress
 539   * @subpackage Plugin
 540   * @since 2.0
 541   *
 542   * @access private
 543   *
 544   * @param string $file The filename of the plugin including the path.
 545   * @param callback $function the function hooked to the 'activate_PLUGIN' action.
 546   */
 547  function register_deactivation_hook($file, $function) {
 548      $file = plugin_basename($file);
 549      add_action('deactivate_' . $file, $function);
 550  }
 551  
 552  /**
 553   * Set the uninstallation hook for a plugin.
 554   *
 555   * Registers the uninstall hook that will be called when the user clicks on the
 556   * uninstall link that calls for the plugin to uninstall itself. The link won't
 557   * be active unless the plugin hooks into the action.
 558   *
 559   * The plugin should not run arbitrary code outside of functions, when
 560   * registering the uninstall hook. In order to run using the hook, the plugin
 561   * will have to be included, which means that any code laying outside of a
 562   * function will be run during the uninstall process. The plugin should not
 563   * hinder the uninstall process.
 564   *
 565   * If the plugin can not be written without running code within the plugin, then
 566   * the plugin should create a file named 'uninstall.php' in the base plugin
 567   * folder. This file will be called, if it exists, during the uninstall process
 568   * bypassing the uninstall hook. The plugin, when using the 'uninstall.php'
 569   * should always check for the 'WP_UNINSTALL_PLUGIN' constant, before
 570   * executing.
 571   *
 572   * @since 2.7
 573   *
 574   * @param string $file
 575   * @param callback $callback The callback to run when the hook is called.
 576   */
 577  function register_uninstall_hook($file, $callback) {
 578      // The option should not be autoloaded, because it is not needed in most
 579      // cases. Emphasis should be put on using the 'uninstall.php' way of
 580      // uninstalling the plugin.
 581      $uninstallable_plugins = (array) get_option('uninstall_plugins');
 582      $uninstallable_plugins[plugin_basename($file)] = $callback;
 583      update_option('uninstall_plugins', $uninstallable_plugins);
 584  }
 585  
 586  /**
 587   * Calls the 'all' hook, which will process the functions hooked into it.
 588   *
 589   * The 'all' hook passes all of the arguments or parameters that were used for
 590   * the hook, which this function was called for.
 591   *
 592   * This function is used internally for apply_filters(), do_action(), and
 593   * do_action_ref_array() and is not meant to be used from outside those
 594   * functions. This function does not check for the existence of the all hook, so
 595   * it will fail unless the all hook exists prior to this function call.
 596   *
 597   * @package WordPress
 598   * @subpackage Plugin
 599   * @since 2.5
 600   * @access private
 601   *
 602   * @uses $wp_filter Used to process all of the functions in the 'all' hook
 603   *
 604   * @param array $args The collected parameters from the hook that was called.
 605   * @param string $hook Optional. The hook name that was used to call the 'all' hook.
 606   */
 607  function _wp_call_all_hook($args) {
 608      global $wp_filter;
 609  
 610      reset( $wp_filter['all'] );
 611      do {
 612          foreach( (array) current($wp_filter['all']) as $the_ )
 613              if ( !is_null($the_['function']) )
 614                  call_user_func_array($the_['function'], $args);
 615  
 616      } while ( next($wp_filter['all']) !== false );
 617  }
 618  
 619  /**
 620   * Build Unique ID for storage and retrieval.
 621   *
 622   * The old way to serialize the callback caused issues and this function is the
 623   * solution. It works by checking for objects and creating an a new property in
 624   * the class to keep track of the object and new objects of the same class that
 625   * need to be added.
 626   *
 627   * It also allows for the removal of actions and filters for objects after they
 628   * change class properties. It is possible to include the property $wp_filter_id
 629   * in your class and set it to "null" or a number to bypass the workaround.
 630   * However this will prevent you from adding new classes and any new classes
 631   * will overwrite the previous hook by the same class.
 632   *
 633   * Functions and static method callbacks are just returned as strings and
 634   * shouldn't have any speed penalty.
 635   *
 636   * @package WordPress
 637   * @subpackage Plugin
 638   * @access private
 639   * @since 2.2.3
 640   * @link http://trac.wordpress.org/ticket/3875
 641   *
 642   * @global array $wp_filter Storage for all of the filters and actions
 643   * @param string $tag Used in counting how many hooks were applied
 644   * @param string|array $function Used for creating unique id
 645   * @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.
 646   * @param string $type filter or action
 647   * @return string Unique ID for usage as array key
 648   */
 649  function _wp_filter_build_unique_id($tag, $function, $priority) {
 650      global $wp_filter;
 651  
 652      // If function then just skip all of the tests and not overwrite the following.
 653      if ( is_string($function) )
 654          return $function;
 655      // Object Class Calling
 656      else if (is_object($function[0]) ) {
 657          $obj_idx = get_class($function[0]).$function[1];
 658          if ( !isset($function[0]->wp_filter_id) ) {
 659              if ( false === $priority )
 660                  return false;
 661              $count = isset($wp_filter[$tag][$priority]) ? count((array)$wp_filter[$tag][$priority]) : 0;
 662              $function[0]->wp_filter_id = $count;
 663              $obj_idx .= $count;
 664              unset($count);
 665          } else
 666              $obj_idx .= $function[0]->wp_filter_id;
 667          return $obj_idx;
 668      }
 669      // Static Calling
 670      else if ( is_string($function[0]) )
 671          return $function[0].$function[1];
 672  }
 673  
 674  ?>