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   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<string, Hook_Callback>>
  24   * @phpstan-implements ArrayAccess<int, array<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<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       */
 205  	public function remove_filter( $hook_name, $callback, $priority ) {
 206          if ( null === $priority ) {
 207              $priority = 0;
 208          }
 209  
 210          $function_key = _wp_filter_build_unique_id( $hook_name, $callback, $priority );
 211  
 212          $exists = isset( $function_key, $this->callbacks[ $priority ][ $function_key ] );
 213  
 214          if ( $exists ) {
 215              unset( $this->callbacks[ $priority ][ $function_key ] );
 216  
 217              if ( ! $this->callbacks[ $priority ] ) {
 218                  unset( $this->callbacks[ $priority ] );
 219  
 220                  $this->priorities = array_keys( $this->callbacks );
 221  
 222                  if ( $this->nesting_level > 0 ) {
 223                      $this->resort_active_iterations();
 224                  }
 225              }
 226          }
 227  
 228          return $exists;
 229      }
 230  
 231      /**
 232       * Checks if a specific callback has been registered for this hook.
 233       *
 234       * When using the `$callback` argument, this function may return a non-boolean value
 235       * that evaluates to false (e.g. 0), so use the `===` operator for testing the return value.
 236       *
 237       * @since 4.7.0
 238       * @since 6.9.0 Added the `$priority` parameter.
 239       *
 240       * @param string                      $hook_name Optional. The name of the filter hook. Default empty.
 241       * @param callable|string|array|false $callback  Optional. The callback to check for.
 242       *                                               This method can be called unconditionally to speculatively check
 243       *                                               a callback that may or may not exist. Default false.
 244       * @param int|false                   $priority  Optional. The specific priority at which to check for the callback.
 245       *                                               Default false.
 246       * @return bool|int If `$callback` is omitted, returns boolean for whether the hook has
 247       *                  anything registered. When checking a specific function, the priority
 248       *                  of that hook is returned, or false if the function is not attached.
 249       *                  If `$callback` and `$priority` are both provided, a boolean is returned
 250       *                  for whether the specific function is registered at that priority.
 251       */
 252  	public function has_filter( $hook_name = '', $callback = false, $priority = false ) {
 253          if ( false === $callback ) {
 254              return $this->has_filters();
 255          }
 256  
 257          $function_key = _wp_filter_build_unique_id( $hook_name, $callback, false );
 258  
 259          if ( ! $function_key ) {
 260              return false;
 261          }
 262  
 263          if ( is_int( $priority ) ) {
 264              return isset( $this->callbacks[ $priority ][ $function_key ] );
 265          }
 266  
 267          foreach ( $this->callbacks as $callback_priority => $callbacks ) {
 268              if ( isset( $callbacks[ $function_key ] ) ) {
 269                  return $callback_priority;
 270              }
 271          }
 272  
 273          return false;
 274      }
 275  
 276      /**
 277       * Checks if any callbacks have been registered for this hook.
 278       *
 279       * @since 4.7.0
 280       *
 281       * @return bool True if callbacks have been registered for the current hook, otherwise false.
 282       */
 283  	public function has_filters() {
 284          foreach ( $this->callbacks as $callbacks ) {
 285              if ( $callbacks ) {
 286                  return true;
 287              }
 288          }
 289  
 290          return false;
 291      }
 292  
 293      /**
 294       * Removes all callbacks from the current filter.
 295       *
 296       * @since 4.7.0
 297       *
 298       * @param int|false $priority Optional. The priority number to remove. Default false.
 299       */
 300  	public function remove_all_filters( $priority = false ) {
 301          if ( ! $this->callbacks ) {
 302              return;
 303          }
 304  
 305          if ( false === $priority ) {
 306              $this->callbacks  = array();
 307              $this->priorities = array();
 308          } elseif ( isset( $this->callbacks[ $priority ] ) ) {
 309              unset( $this->callbacks[ $priority ] );
 310              $this->priorities = array_keys( $this->callbacks );
 311          }
 312  
 313          if ( $this->nesting_level > 0 ) {
 314              $this->resort_active_iterations();
 315          }
 316      }
 317  
 318      /**
 319       * Calls the callback functions that have been added to a filter hook.
 320       *
 321       * @since 4.7.0
 322       *
 323       * @param mixed $value The value to filter.
 324       * @param array $args  Additional parameters to pass to the callback functions.
 325       *                     This array is expected to include $value at index 0.
 326       * @return mixed The filtered value after all hooked functions are applied to it.
 327       */
 328  	public function apply_filters( $value, $args ) {
 329          if ( ! $this->callbacks ) {
 330              return $value;
 331          }
 332  
 333          $nesting_level = $this->nesting_level++;
 334  
 335          $this->iterations[ $nesting_level ] = $this->priorities;
 336  
 337          $num_args = count( $args );
 338  
 339          do {
 340              $this->current_priority[ $nesting_level ] = current( $this->iterations[ $nesting_level ] );
 341  
 342              $priority = $this->current_priority[ $nesting_level ];
 343  
 344              foreach ( $this->callbacks[ $priority ] as $the_ ) {
 345                  if ( ! $this->doing_action ) {
 346                      $args[0] = $value;
 347                  }
 348  
 349                  // Avoid the array_slice() if possible.
 350                  if ( 0 === $the_['accepted_args'] ) {
 351                      $value = call_user_func( $the_['function'] );
 352                  } elseif ( $the_['accepted_args'] >= $num_args ) {
 353                      $value = call_user_func_array( $the_['function'], $args );
 354                  } else {
 355                      $value = call_user_func_array( $the_['function'], array_slice( $args, 0, $the_['accepted_args'] ) );
 356                  }
 357              }
 358          } while ( false !== next( $this->iterations[ $nesting_level ] ) );
 359  
 360          unset( $this->iterations[ $nesting_level ] );
 361          unset( $this->current_priority[ $nesting_level ] );
 362  
 363          --$this->nesting_level;
 364  
 365          return $value;
 366      }
 367  
 368      /**
 369       * Calls the callback functions that have been added to an action hook.
 370       *
 371       * @since 4.7.0
 372       *
 373       * @param array $args Parameters to pass to the callback functions.
 374       */
 375  	public function do_action( $args ) {
 376          $this->doing_action = true;
 377          $this->apply_filters( '', $args );
 378  
 379          // If there are recursive calls to the current action, we haven't finished it until we get to the last one.
 380          if ( ! $this->nesting_level ) {
 381              $this->doing_action = false;
 382          }
 383      }
 384  
 385      /**
 386       * Processes the functions hooked into the 'all' hook.
 387       *
 388       * @since 4.7.0
 389       *
 390       * @param array $args Arguments to pass to the hook callbacks. Passed by reference.
 391       */
 392  	public function do_all_hook( &$args ) {
 393          $nesting_level                      = $this->nesting_level++;
 394          $this->iterations[ $nesting_level ] = $this->priorities;
 395  
 396          do {
 397              $priority = current( $this->iterations[ $nesting_level ] );
 398  
 399              foreach ( $this->callbacks[ $priority ] as $the_ ) {
 400                  call_user_func_array( $the_['function'], $args );
 401              }
 402          } while ( false !== next( $this->iterations[ $nesting_level ] ) );
 403  
 404          unset( $this->iterations[ $nesting_level ] );
 405          --$this->nesting_level;
 406      }
 407  
 408      /**
 409       * Return the current priority level of the currently running iteration of the hook.
 410       *
 411       * @since 4.7.0
 412       *
 413       * @return int|false If the hook is running, return the current priority level.
 414       *                   If it isn't running, return false.
 415       */
 416  	public function current_priority() {
 417          if ( false === current( $this->iterations ) ) {
 418              return false;
 419          }
 420  
 421          return current( current( $this->iterations ) );
 422      }
 423  
 424      /**
 425       * Normalizes filters set up before WordPress has initialized to WP_Hook objects.
 426       *
 427       * The `$filters` parameter should be an array keyed by hook name, with values
 428       * containing either:
 429       *
 430       *  - A `WP_Hook` instance
 431       *  - An array of callbacks keyed by their priorities
 432       *
 433       * Examples:
 434       *
 435       *     $filters = array(
 436       *         'wp_fatal_error_handler_enabled' => array(
 437       *             10 => array(
 438       *                 array(
 439       *                     'accepted_args' => 0,
 440       *                     'function'      => function() {
 441       *                         return false;
 442       *                     },
 443       *                 ),
 444       *             ),
 445       *         ),
 446       *     );
 447       *
 448       * @since 4.7.0
 449       *
 450       * @param array $filters Filters to normalize. See documentation above for details.
 451       * @phpstan-param array<string, WP_Hook|array<int, array<Hook_Callback>>> $filters
 452       * @return array<string, WP_Hook> Array of normalized filters keyed by hook name.
 453       */
 454  	public static function build_preinitialized_hooks( $filters ) {
 455          /** @var array<string, WP_Hook> $normalized */
 456          $normalized = array();
 457  
 458          foreach ( $filters as $hook_name => $callback_groups ) {
 459              if ( $callback_groups instanceof WP_Hook ) {
 460                  $normalized[ $hook_name ] = $callback_groups;
 461                  continue;
 462              }
 463  
 464              $hook = new WP_Hook();
 465  
 466              // Loop through callback groups.
 467              foreach ( $callback_groups as $priority => $callbacks ) {
 468  
 469                  // Loop through callbacks.
 470                  foreach ( $callbacks as $cb ) {
 471                      $hook->add_filter( $hook_name, $cb['function'], $priority, $cb['accepted_args'] );
 472                  }
 473              }
 474  
 475              $normalized[ $hook_name ] = $hook;
 476          }
 477  
 478          return $normalized;
 479      }
 480  
 481      /**
 482       * Determines whether an offset value exists.
 483       *
 484       * @since 4.7.0
 485       *
 486       * @link https://www.php.net/manual/en/arrayaccess.offsetexists.php
 487       *
 488       * @param int $offset An offset to check for.
 489       * @return bool True if the offset exists, false otherwise.
 490       */
 491      #[ReturnTypeWillChange]
 492  	public function offsetExists( $offset ) {
 493          return isset( $this->callbacks[ $offset ] );
 494      }
 495  
 496      /**
 497       * Retrieves a value at a specified offset.
 498       *
 499       * @since 4.7.0
 500       *
 501       * @link https://www.php.net/manual/en/arrayaccess.offsetget.php
 502       *
 503       * @param int $offset The offset to retrieve.
 504       * @return array|null If set, the value at the specified offset, null otherwise.
 505       * @phpstan-return array<string, Hook_Callback>|null
 506       */
 507      #[ReturnTypeWillChange]
 508  	public function offsetGet( $offset ) {
 509          return $this->callbacks[ $offset ] ?? null;
 510      }
 511  
 512      /**
 513       * Sets a value at a specified offset.
 514       *
 515       * @since 4.7.0
 516       *
 517       * @link https://www.php.net/manual/en/arrayaccess.offsetset.php
 518       *
 519       * @param int|null $offset The offset to assign the value to.
 520       * @param array    $value The value to set.
 521       * @phpstan-param array<string, Hook_Callback> $value
 522       */
 523      #[ReturnTypeWillChange]
 524  	public function offsetSet( $offset, $value ) {
 525          if ( is_null( $offset ) ) {
 526              $this->callbacks[] = $value;
 527          } else {
 528              $this->callbacks[ $offset ] = $value;
 529          }
 530  
 531          $this->priorities = array_keys( $this->callbacks );
 532      }
 533  
 534      /**
 535       * Unsets a specified offset.
 536       *
 537       * @since 4.7.0
 538       *
 539       * @link https://www.php.net/manual/en/arrayaccess.offsetunset.php
 540       *
 541       * @param int $offset The offset to unset.
 542       */
 543      #[ReturnTypeWillChange]
 544  	public function offsetUnset( $offset ) {
 545          unset( $this->callbacks[ $offset ] );
 546          $this->priorities = array_keys( $this->callbacks );
 547      }
 548  
 549      /**
 550       * Returns the current element.
 551       *
 552       * @since 4.7.0
 553       *
 554       * @link https://www.php.net/manual/en/iterator.current.php
 555       *
 556       * @return array|false Array of callbacks at current priority, false if there are no more elements.
 557       * @phpstan-return array<string, Hook_Callback>|false
 558       */
 559      #[ReturnTypeWillChange]
 560  	public function current() {
 561          return current( $this->callbacks );
 562      }
 563  
 564      /**
 565       * Moves forward to the next element.
 566       *
 567       * @since 4.7.0
 568       *
 569       * @link https://www.php.net/manual/en/iterator.next.php
 570       *
 571       * @return array|false Array of callbacks at next priority, false if there are no more elements.
 572       * @phpstan-return array<string, Hook_Callback>|false
 573       */
 574      #[ReturnTypeWillChange]
 575  	public function next() {
 576          return next( $this->callbacks );
 577      }
 578  
 579      /**
 580       * Returns the key of the current element.
 581       *
 582       * @since 4.7.0
 583       *
 584       * @link https://www.php.net/manual/en/iterator.key.php
 585       *
 586       * @return int|null Returns current priority on success, or NULL on failure
 587       */
 588      #[ReturnTypeWillChange]
 589  	public function key() {
 590          return key( $this->callbacks );
 591      }
 592  
 593      /**
 594       * Checks if current position is valid.
 595       *
 596       * @since 4.7.0
 597       *
 598       * @link https://www.php.net/manual/en/iterator.valid.php
 599       *
 600       * @return bool Whether the current position is valid.
 601       */
 602      #[ReturnTypeWillChange]
 603  	public function valid() {
 604          return key( $this->callbacks ) !== null;
 605      }
 606  
 607      /**
 608       * Rewinds the Iterator to the first element.
 609       *
 610       * @since 4.7.0
 611       *
 612       * @link https://www.php.net/manual/en/iterator.rewind.php
 613       */
 614      #[ReturnTypeWillChange]
 615  	public function rewind() {
 616          reset( $this->callbacks );
 617      }
 618  }