[Summary view] [Print] [Text view]

   1  <?php
   2  /**
   3   * Plugin API: WP_Hook class
   4   *
   5   * @package WordPress
   6   * @subpackage Plugin
   7   * @since 4.7.0
   8   */
   9  
  10  /**
  11   * Core class used to implement action and filter hook functionality.
  12   *
  13   * @since 4.7.0
  14   *
  15   * @see Iterator
  16   * @see ArrayAccess
  17   *
  18   * @phpstan-type Hook_Callback array{
  19   *   function: callable,
  20   *   accepted_args: int,
  21   * }
  22   *
  23   * @phpstan-implements Iterator<int, array<non-decimal-int-string, Hook_Callback>>
  24   * @phpstan-implements ArrayAccess<int, array<non-decimal-int-string, Hook_Callback>>
  25   */
  26  #[AllowDynamicProperties]
  27  final class WP_Hook implements Iterator, ArrayAccess {
  28  
  29      /**
  30       * Hook callbacks keyed by priority.
  31       *
  32       * @since 4.7.0
  33       * @var array
  34       * @phpstan-var array<int, array<non-decimal-int-string, Hook_Callback>>
  35       */
  36      public $callbacks = array();
  37  
  38      /**
  39       * Priorities list.
  40       *
  41       * @since 6.4.0
  42       * @var list<int>
  43       */
  44      protected $priorities = array();
  45  
  46      /**
  47       * The priority keys of actively running iterations of a hook.
  48       *
  49       * @since 4.7.0
  50       * @var array<int, list<int>>
  51       */
  52      private $iterations = array();
  53  
  54      /**
  55       * The current priority of actively running iterations of a hook.
  56       *
  57       * @since 4.7.0
  58       * @var array<int, int>
  59       */
  60      private $current_priority = array();
  61  
  62      /**
  63       * Number of levels this hook can be recursively called.
  64       *
  65       * @since 4.7.0
  66       * @var int
  67       */
  68      private $nesting_level = 0;
  69  
  70      /**
  71       * Flag for if we're currently doing an action, rather than a filter.
  72       *
  73       * @since 4.7.0
  74       * @var bool
  75       */
  76      private $doing_action = false;
  77  
  78      /**
  79       * Adds a callback function to a filter hook.
  80       *
  81       * @since 4.7.0
  82       *
  83       * @param string   $hook_name     The name of the filter to add the callback to.
  84       * @param callable $callback      The callback to be run when the filter is applied.
  85       * @param int      $priority      The order in which the functions associated with a particular filter
  86       *                                are executed. Lower numbers correspond with earlier execution,
  87       *                                and functions with the same priority are executed in the order
  88       *                                in which they were added to the filter.
  89       * @param int      $accepted_args The number of arguments the function accepts.
  90       */
  91  	public function add_filter( $hook_name, $callback, $priority, $accepted_args ) {
  92          if ( null === $priority ) {
  93              $priority = 0;
  94          }
  95  
  96          $idx = _wp_filter_build_unique_id( $hook_name, $callback, $priority );
  97          if ( null === $idx ) {
  98              return;
  99          }
 100  
 101          $priority_existed = isset( $this->callbacks[ $priority ] );
 102  
 103          $this->callbacks[ $priority ][ $idx ] = array(
 104              'function'      => $callback,
 105              'accepted_args' => (int) $accepted_args,
 106          );
 107  
 108          // If we're adding a new priority to the list, put them back in sorted order.
 109          if ( ! $priority_existed && count( $this->callbacks ) > 1 ) {
 110              ksort( $this->callbacks, SORT_NUMERIC );
 111          }
 112  
 113          $this->priorities = array_keys( $this->callbacks );
 114  
 115          if ( $this->nesting_level > 0 ) {
 116              $this->resort_active_iterations( $priority, $priority_existed );
 117          }
 118      }
 119  
 120      /**
 121       * Handles resetting callback priority keys mid-iteration.
 122       *
 123       * @since 4.7.0
 124       *
 125       * @param false|int $new_priority     Optional. The priority of the new filter being added. Default false,
 126       *                                    for no priority being added.
 127       * @param bool      $priority_existed Optional. Flag for whether the priority already existed before the new
 128       *                                    filter was added. Default false.
 129       */
 130  	private function resort_active_iterations( $new_priority = false, $priority_existed = false ) {
 131          $new_priorities = $this->priorities;
 132  
 133          // If there are no remaining hooks, clear out all running iterations.
 134          if ( ! $new_priorities ) {
 135              foreach ( $this->iterations as $index => $iteration ) {
 136                  $this->iterations[ $index ] = $new_priorities;
 137              }
 138  
 139              return;
 140          }
 141  
 142          $min = min( $new_priorities );
 143  
 144          foreach ( $this->iterations as $index => &$iteration ) {
 145              $current = current( $iteration );
 146  
 147              // If we're already at the end of this iteration, just leave the array pointer where it is.
 148              if ( false === $current ) {
 149                  continue;
 150              }
 151  
 152              $iteration = $new_priorities;
 153  
 154              if ( $current < $min ) {
 155                  array_unshift( $iteration, $current );
 156                  continue;
 157              }
 158  
 159              while ( current( $iteration ) < $current ) {
 160                  if ( false === next( $iteration ) ) {
 161                      break;
 162                  }
 163              }
 164  
 165              // If we have a new priority that didn't exist, but ::apply_filters() or ::do_action() thinks it's the current priority...
 166              if ( $new_priority === $this->current_priority[ $index ] && ! $priority_existed ) {
 167                  /*
 168                   * ...and the new priority is the same as what $this->iterations thinks is the previous
 169                   * priority, we need to move back to it.
 170                   */
 171  
 172                  if ( false === current( $iteration ) ) {
 173                      // If we've already moved off the end of the array, go back to the last element.
 174                      $prev = end( $iteration );
 175                  } else {
 176                      // Otherwise, just go back to the previous element.
 177                      $prev = prev( $iteration );
 178                  }
 179  
 180                  if ( false === $prev ) {
 181                      // Start of the array. Reset, and go about our day.
 182                      reset( $iteration );
 183                  } elseif ( $new_priority !== $prev ) {
 184                      // Previous wasn't the same. Move forward again.
 185                      next( $iteration );
 186                  }
 187              }
 188          }
 189  
 190          unset( $iteration );
 191      }
 192  
 193      /**
 194       * Removes a callback function from a filter hook.
 195       *
 196       * @since 4.7.0
 197       *
 198       * @param string                $hook_name The filter hook to which the function to be removed is hooked.
 199       * @param callable|string|array $callback  The callback to be removed from running when the filter is applied.
 200       *                                         This method can be called unconditionally to speculatively remove
 201       *                                         a callback that may or may not exist.
 202       * @param int                   $priority  The exact priority used when adding the original filter callback.
 203       * @return bool Whether the callback existed before it was removed.
 204       * @phpstan-param Maybe_Callable $callback
 205       */
 206  	public function remove_filter( $hook_name, $callback, $priority ) {
 207          if ( null === $priority ) {
 208              $priority = 0;
 209          }
 210  
 211          $function_key = _wp_filter_build_unique_id( $hook_name, $callback, $priority );
 212  
 213          $exists = isset( $function_key, $this->callbacks[ $priority ][ $function_key ] );
 214  
 215          if ( $exists ) {
 216              unset( $this->callbacks[ $priority ][ $function_key ] );
 217  
 218              if ( ! $this->callbacks[ $priority ] ) {
 219                  unset( $this->callbacks[ $priority ] );
 220  
 221                  $this->priorities = array_keys( $this->callbacks );
 222  
 223                  if ( $this->nesting_level > 0 ) {
 224                      $this->resort_active_iterations();
 225                  }
 226              }
 227          }
 228  
 229          return $exists;
 230      }
 231  
 232      /**
 233       * Checks if a specific callback has been registered for this hook.
 234       *
 235       * When using the `$callback` argument, this function may return a non-boolean value
 236       * that evaluates to false (e.g. 0), so use the `===` operator for testing the return value.
 237       *
 238       * @since 4.7.0
 239       * @since 6.9.0 Added the `$priority` parameter.
 240       *
 241       * @param string                      $hook_name Optional. The name of the filter hook. Default empty.
 242       * @param callable|string|array|false $callback  Optional. The callback to check for.
 243       *                                               This method can be called unconditionally to speculatively check
 244       *                                               a callback that may or may not exist. Default false.
 245       * @param int|false                   $priority  Optional. The specific priority at which to check for the callback.
 246       *                                               Default false.
 247       * @return bool|int If `$callback` is omitted, returns boolean for whether the hook has
 248       *                  anything registered. When checking a specific function, the priority
 249       *                  of that hook is returned, or false if the function is not attached.
 250       *                  If `$callback` and `$priority` are both provided, a boolean is returned
 251       *                  for whether the specific function is registered at that priority.
 252       * @phpstan-param Maybe_Callable|false $callback
 253       * @phpstan-return (
 254       *     $callback is false
 255       *         ? bool
 256       *         : ( $priority is int
 257       *             ? bool
 258       *             : false|int )
 259       * )
 260       */
 261  	public function has_filter( $hook_name = '', $callback = false, $priority = false ) {
 262          if ( false === $callback ) {
 263              return $this->has_filters();
 264          }
 265  
 266          $function_key = _wp_filter_build_unique_id( $hook_name, $callback, is_int( $priority ) ? $priority : 10 );
 267  
 268          if ( ! $function_key ) {
 269              return false;
 270          }
 271  
 272          if ( is_int( $priority ) ) {
 273              return isset( $this->callbacks[ $priority ][ $function_key ] );
 274          }
 275  
 276          foreach ( $this->callbacks as $callback_priority => $callbacks ) {
 277              if ( isset( $callbacks[ $function_key ] ) ) {
 278                  return $callback_priority;
 279              }
 280          }
 281  
 282          return false;
 283      }
 284  
 285      /**
 286       * Checks if any callbacks have been registered for this hook.
 287       *
 288       * @since 4.7.0
 289       *
 290       * @return bool True if callbacks have been registered for the current hook, otherwise false.
 291       */
 292  	public function has_filters() {
 293          foreach ( $this->callbacks as $callbacks ) {
 294              if ( $callbacks ) {
 295                  return true;
 296              }
 297          }
 298  
 299          return false;
 300      }
 301  
 302      /**
 303       * Removes all callbacks from the current filter.
 304       *
 305       * @since 4.7.0
 306       *
 307       * @param int|false $priority Optional. The priority number to remove. Default false.
 308       */
 309  	public function remove_all_filters( $priority = false ) {
 310          if ( ! $this->callbacks ) {
 311              return;
 312          }
 313  
 314          if ( false === $priority ) {
 315              $this->callbacks  = array();
 316              $this->priorities = array();
 317          } elseif ( isset( $this->callbacks[ $priority ] ) ) {
 318              unset( $this->callbacks[ $priority ] );
 319              $this->priorities = array_keys( $this->callbacks );
 320          }
 321  
 322          if ( $this->nesting_level > 0 ) {
 323              $this->resort_active_iterations();
 324          }
 325      }
 326  
 327      /**
 328       * Calls the callback functions that have been added to a filter hook.
 329       *
 330       * @since 4.7.0
 331       *
 332       * @param mixed       $value The value to filter.
 333       * @param list<mixed> $args  Additional parameters to pass to the callback functions.
 334       *                           When filtering, this array is expected to include $value
 335       *                           at index 0. When called for an action by WP_Hook::do_action(),
 336       *                           it contains only the action arguments.
 337       * @return mixed The filtered value after all hooked functions are applied to it.
 338       */
 339  	public function apply_filters( $value, $args ) {
 340          if ( ! $this->callbacks ) {
 341              return $value;
 342          }
 343  
 344          $nesting_level = $this->nesting_level++;
 345  
 346          $this->iterations[ $nesting_level ] = $this->priorities;
 347  
 348          $num_args = count( $args );
 349  
 350          do {
 351              $priority = current( $this->iterations[ $nesting_level ] );
 352  
 353              if ( false === $priority ) {
 354                  // This is not expected to occur since the hook is known to have callbacks at one or more priorities.
 355                  break;
 356              }
 357  
 358              $this->current_priority[ $nesting_level ] = $priority;
 359  
 360              foreach ( $this->callbacks[ $priority ] as $the_ ) {
 361                  if ( ! $this->doing_action ) {
 362                      $args[0] = $value;
 363                  }
 364  
 365                  // Avoid the array_slice() if possible.
 366                  if ( 0 === $the_['accepted_args'] ) {
 367                      $value = call_user_func( $the_['function'] );
 368                  } elseif ( $the_['accepted_args'] >= $num_args ) {
 369                      $value = call_user_func_array( $the_['function'], $args );
 370                  } else {
 371                      $value = call_user_func_array( $the_['function'], array_slice( $args, 0, $the_['accepted_args'] ) );
 372                  }
 373              }
 374          } while ( false !== next( $this->iterations[ $nesting_level ] ) );
 375  
 376          unset( $this->iterations[ $nesting_level ] );
 377          unset( $this->current_priority[ $nesting_level ] );
 378  
 379          --$this->nesting_level;
 380  
 381          return $value;
 382      }
 383  
 384      /**
 385       * Calls the callback functions that have been added to an action hook.
 386       *
 387       * @since 4.7.0
 388       *
 389       * @param list<mixed> $args Parameters to pass to the callback functions.
 390       */
 391  	public function do_action( $args ) {
 392          $this->doing_action = true;
 393          $this->apply_filters( '', $args );
 394  
 395          // If there are recursive calls to the current action, we haven't finished it until we get to the last one.
 396          if ( ! $this->nesting_level ) {
 397              $this->doing_action = false;
 398          }
 399      }
 400  
 401      /**
 402       * Processes the functions hooked into the 'all' hook.
 403       *
 404       * @since 4.7.0
 405       *
 406       * @param list<mixed> $args Arguments to pass to the hook callbacks. Passed by reference.
 407       */
 408  	public function do_all_hook( &$args ) {
 409          $nesting_level                      = $this->nesting_level++;
 410          $this->iterations[ $nesting_level ] = $this->priorities;
 411  
 412          do {
 413              $priority = current( $this->iterations[ $nesting_level ] );
 414  
 415              foreach ( $this->callbacks[ $priority ] as $the_ ) {
 416                  call_user_func_array( $the_['function'], $args );
 417              }
 418          } while ( false !== next( $this->iterations[ $nesting_level ] ) );
 419  
 420          unset( $this->iterations[ $nesting_level ] );
 421          --$this->nesting_level;
 422      }
 423  
 424      /**
 425       * Return the current priority level of the currently running iteration of the hook.
 426       *
 427       * @since 4.7.0
 428       *
 429       * @return int|false If the hook is running, return the current priority level.
 430       *                   If it isn't running, return false.
 431       */
 432  	public function current_priority() {
 433          if ( false === current( $this->iterations ) ) {
 434              return false;
 435          }
 436  
 437          return current( current( $this->iterations ) );
 438      }
 439  
 440      /**
 441       * Normalizes filters set up before WordPress has initialized to WP_Hook objects.
 442       *
 443       * The `$filters` parameter should be an array keyed by hook name, with values
 444       * containing either:
 445       *
 446       *  - A `WP_Hook` instance
 447       *  - An array of callbacks keyed by their priorities
 448       *
 449       * Examples:
 450       *
 451       *     $filters = array(
 452       *         'wp_fatal_error_handler_enabled' => array(
 453       *             10 => array(
 454       *                 array(
 455       *                     'accepted_args' => 0,
 456       *                     'function'      => function() {
 457       *                         return false;
 458       *                     },
 459       *                 ),
 460       *             ),
 461       *         ),
 462       *     );
 463       *
 464       * @since 4.7.0
 465       *
 466       * @param array $filters Filters to normalize. See documentation above for details.
 467       * @phpstan-param array<string, WP_Hook|array<int, array<Hook_Callback>>> $filters
 468       * @return array<string, WP_Hook> Array of normalized filters keyed by hook name.
 469       */
 470  	public static function build_preinitialized_hooks( $filters ) {
 471          /** @var array<string, WP_Hook> $normalized */
 472          $normalized = array();
 473  
 474          foreach ( $filters as $hook_name => $callback_groups ) {
 475              if ( $callback_groups instanceof WP_Hook ) {
 476                  $normalized[ $hook_name ] = $callback_groups;
 477                  continue;
 478              }
 479  
 480              $hook = new WP_Hook();
 481  
 482              // Loop through callback groups.
 483              foreach ( $callback_groups as $priority => $callbacks ) {
 484  
 485                  // Loop through callbacks.
 486                  foreach ( $callbacks as $cb ) {
 487                      $hook->add_filter( $hook_name, $cb['function'], $priority, $cb['accepted_args'] );
 488                  }
 489              }
 490  
 491              $normalized[ $hook_name ] = $hook;
 492          }
 493  
 494          return $normalized;
 495      }
 496  
 497      /**
 498       * Determines whether an offset value exists.
 499       *
 500       * @since 4.7.0
 501       *
 502       * @link https://www.php.net/manual/en/arrayaccess.offsetexists.php
 503       *
 504       * @param int $offset An offset to check for.
 505       * @return bool True if the offset exists, false otherwise.
 506       */
 507      #[ReturnTypeWillChange]
 508  	public function offsetExists( $offset ) {
 509          return isset( $this->callbacks[ $offset ] );
 510      }
 511  
 512      /**
 513       * Retrieves a value at a specified offset.
 514       *
 515       * @since 4.7.0
 516       *
 517       * @link https://www.php.net/manual/en/arrayaccess.offsetget.php
 518       *
 519       * @param int $offset The offset to retrieve.
 520       * @return array|null If set, the value at the specified offset, null otherwise.
 521       * @phpstan-return array<non-decimal-int-string, Hook_Callback>|null
 522       */
 523      #[ReturnTypeWillChange]
 524  	public function offsetGet( $offset ) {
 525          return $this->callbacks[ $offset ] ?? null;
 526      }
 527  
 528      /**
 529       * Sets a value at a specified offset.
 530       *
 531       * @since 4.7.0
 532       *
 533       * @link https://www.php.net/manual/en/arrayaccess.offsetset.php
 534       *
 535       * @param int|null $offset The offset to assign the value to.
 536       * @param array    $value  The value to set.
 537       * @phpstan-param array<non-decimal-int-string, Hook_Callback> $value
 538       */
 539      #[ReturnTypeWillChange]
 540  	public function offsetSet( $offset, $value ) {
 541          if ( is_null( $offset ) ) {
 542              $this->callbacks[] = $value;
 543          } else {
 544              $this->callbacks[ $offset ] = $value;
 545          }
 546  
 547          $this->priorities = array_keys( $this->callbacks );
 548      }
 549  
 550      /**
 551       * Unsets a specified offset.
 552       *
 553       * @since 4.7.0
 554       *
 555       * @link https://www.php.net/manual/en/arrayaccess.offsetunset.php
 556       *
 557       * @param int $offset The offset to unset.
 558       */
 559      #[ReturnTypeWillChange]
 560  	public function offsetUnset( $offset ) {
 561          unset( $this->callbacks[ $offset ] );
 562          $this->priorities = array_keys( $this->callbacks );
 563      }
 564  
 565      /**
 566       * Returns the current element.
 567       *
 568       * @since 4.7.0
 569       *
 570       * @link https://www.php.net/manual/en/iterator.current.php
 571       *
 572       * @return array|false Array of callbacks at current priority, false if there are no more elements.
 573       * @phpstan-return array<non-decimal-int-string, Hook_Callback>|false
 574       */
 575      #[ReturnTypeWillChange]
 576  	public function current() {
 577          return current( $this->callbacks );
 578      }
 579  
 580      /**
 581       * Moves forward to the next element.
 582       *
 583       * @since 4.7.0
 584       *
 585       * @link https://www.php.net/manual/en/iterator.next.php
 586       *
 587       * @return array|false Array of callbacks at next priority, false if there are no more elements.
 588       * @phpstan-return array<non-decimal-int-string, Hook_Callback>|false
 589       */
 590      #[ReturnTypeWillChange]
 591  	public function next() {
 592          return next( $this->callbacks );
 593      }
 594  
 595      /**
 596       * Returns the key of the current element.
 597       *
 598       * @since 4.7.0
 599       *
 600       * @link https://www.php.net/manual/en/iterator.key.php
 601       *
 602       * @return int|null Returns current priority on success, or NULL on failure
 603       */
 604      #[ReturnTypeWillChange]
 605  	public function key() {
 606          return key( $this->callbacks );
 607      }
 608  
 609      /**
 610       * Checks if current position is valid.
 611       *
 612       * @since 4.7.0
 613       *
 614       * @link https://www.php.net/manual/en/iterator.valid.php
 615       *
 616       * @return bool Whether the current position is valid.
 617       */
 618      #[ReturnTypeWillChange]
 619  	public function valid() {
 620          return key( $this->callbacks ) !== null;
 621      }
 622  
 623      /**
 624       * Rewinds the Iterator to the first element.
 625       *
 626       * @since 4.7.0
 627       *
 628       * @link https://www.php.net/manual/en/iterator.rewind.php
 629       */
 630      #[ReturnTypeWillChange]
 631  	public function rewind() {
 632          reset( $this->callbacks );
 633      }
 634  }